From 22a07e9bbe682d6e36efd97fdd44b82db8fcbfd4 Mon Sep 17 00:00:00 2001 From: Brian Warner Date: Wed, 4 Aug 2010 00:26:29 -0700 Subject: [PATCH] Rewrite immutable downloader (#798). This patch adds the new downloader itself. --- src/allmydata/immutable/download.py | 1321 ----------------- .../immutable/downloader/__init__.py | 0 src/allmydata/immutable/downloader/common.py | 13 + src/allmydata/immutable/downloader/fetcher.py | 229 +++ src/allmydata/immutable/downloader/finder.py | 202 +++ src/allmydata/immutable/downloader/node.py | 471 ++++++ .../immutable/downloader/segmentation.py | 160 ++ src/allmydata/immutable/downloader/share.py | 848 +++++++++++ src/allmydata/immutable/downloader/status.py | 170 +++ 9 files changed, 2093 insertions(+), 1321 deletions(-) delete mode 100644 src/allmydata/immutable/download.py create mode 100644 src/allmydata/immutable/downloader/__init__.py create mode 100644 src/allmydata/immutable/downloader/common.py create mode 100644 src/allmydata/immutable/downloader/fetcher.py create mode 100644 src/allmydata/immutable/downloader/finder.py create mode 100644 src/allmydata/immutable/downloader/node.py create mode 100644 src/allmydata/immutable/downloader/segmentation.py create mode 100644 src/allmydata/immutable/downloader/share.py create mode 100644 src/allmydata/immutable/downloader/status.py diff --git a/src/allmydata/immutable/download.py b/src/allmydata/immutable/download.py deleted file mode 100644 index eb02c6aa..00000000 --- a/src/allmydata/immutable/download.py +++ /dev/null @@ -1,1321 +0,0 @@ -import random, weakref, itertools, time -from zope.interface import implements -from twisted.internet import defer, reactor -from twisted.internet.interfaces import IPushProducer, IConsumer -from foolscap.api import DeadReferenceError, RemoteException, eventually - -from allmydata.util import base32, deferredutil, hashutil, log, mathutil, idlib -from allmydata.util.assertutil import _assert, precondition -from allmydata import codec, hashtree, uri -from allmydata.interfaces import IDownloadTarget, IDownloader, IVerifierURI, \ - IDownloadStatus, IDownloadResults, IValidatedThingProxy, \ - IStorageBroker, NotEnoughSharesError, NoSharesError, NoServersError, \ - UnableToFetchCriticalDownloadDataError -from allmydata.immutable import layout -from allmydata.monitor import Monitor -from pycryptopp.cipher.aes import AES - -class IntegrityCheckReject(Exception): - pass - -class BadURIExtensionHashValue(IntegrityCheckReject): - pass -class BadURIExtension(IntegrityCheckReject): - pass -class UnsupportedErasureCodec(BadURIExtension): - pass -class BadCrypttextHashValue(IntegrityCheckReject): - pass -class BadOrMissingHash(IntegrityCheckReject): - pass - -class DownloadStopped(Exception): - pass - -class DownloadResults: - implements(IDownloadResults) - - def __init__(self): - self.servers_used = set() - self.server_problems = {} - self.servermap = {} - self.timings = {} - self.file_size = None - -class DecryptingTarget(log.PrefixingLogMixin): - implements(IDownloadTarget, IConsumer) - def __init__(self, target, key, _log_msg_id=None): - precondition(IDownloadTarget.providedBy(target), target) - self.target = target - self._decryptor = AES(key) - prefix = str(target) - log.PrefixingLogMixin.__init__(self, "allmydata.immutable.download", _log_msg_id, prefix=prefix) - # methods to satisfy the IConsumer interface - def registerProducer(self, producer, streaming): - if IConsumer.providedBy(self.target): - self.target.registerProducer(producer, streaming) - def unregisterProducer(self): - if IConsumer.providedBy(self.target): - self.target.unregisterProducer() - def write(self, ciphertext): - plaintext = self._decryptor.process(ciphertext) - self.target.write(plaintext) - def open(self, size): - self.target.open(size) - def close(self): - self.target.close() - def finish(self): - return self.target.finish() - # The following methods is just to pass through to the next target, and - # just because that target might be a repairer.DownUpConnector, and just - # because the current CHKUpload object expects to find the storage index - # in its Uploadable. - def set_storageindex(self, storageindex): - self.target.set_storageindex(storageindex) - def set_encodingparams(self, encodingparams): - self.target.set_encodingparams(encodingparams) - -class ValidatedThingObtainer: - def __init__(self, validatedthingproxies, debugname, log_id): - self._validatedthingproxies = validatedthingproxies - self._debugname = debugname - self._log_id = log_id - - def _bad(self, f, validatedthingproxy): - f.trap(RemoteException, DeadReferenceError, - IntegrityCheckReject, layout.LayoutInvalid, - layout.ShareVersionIncompatible) - level = log.WEIRD - if f.check(DeadReferenceError): - level = log.UNUSUAL - elif f.check(RemoteException): - level = log.WEIRD - else: - level = log.SCARY - log.msg(parent=self._log_id, facility="tahoe.immutable.download", - format="operation %(op)s from validatedthingproxy %(validatedthingproxy)s failed", - op=self._debugname, validatedthingproxy=str(validatedthingproxy), - failure=f, level=level, umid="JGXxBA") - if not self._validatedthingproxies: - raise UnableToFetchCriticalDownloadDataError("ran out of peers, last error was %s" % (f,)) - # try again with a different one - d = self._try_the_next_one() - return d - - def _try_the_next_one(self): - vtp = self._validatedthingproxies.pop(0) - # start() obtains, validates, and callsback-with the thing or else - # errbacks - d = vtp.start() - d.addErrback(self._bad, vtp) - return d - - def start(self): - return self._try_the_next_one() - -class ValidatedCrypttextHashTreeProxy: - implements(IValidatedThingProxy) - """ I am a front-end for a remote crypttext hash tree using a local - ReadBucketProxy -- I use its get_crypttext_hashes() method and offer the - Validated Thing protocol (i.e., I have a start() method that fires with - self once I get a valid one).""" - def __init__(self, readbucketproxy, crypttext_hash_tree, num_segments, - fetch_failures=None): - # fetch_failures is for debugging -- see test_encode.py - self._readbucketproxy = readbucketproxy - self._num_segments = num_segments - self._fetch_failures = fetch_failures - self._crypttext_hash_tree = crypttext_hash_tree - - def _validate(self, proposal): - ct_hashes = dict(list(enumerate(proposal))) - try: - self._crypttext_hash_tree.set_hashes(ct_hashes) - except (hashtree.BadHashError, hashtree.NotEnoughHashesError), le: - if self._fetch_failures is not None: - self._fetch_failures["crypttext_hash_tree"] += 1 - raise BadOrMissingHash(le) - # If we now have enough of the crypttext hash tree to integrity-check - # *any* segment of ciphertext, then we are done. TODO: It would have - # better alacrity if we downloaded only part of the crypttext hash - # tree at a time. - for segnum in range(self._num_segments): - if self._crypttext_hash_tree.needed_hashes(segnum): - raise BadOrMissingHash("not enough hashes to validate segment number %d" % (segnum,)) - return self - - def start(self): - d = self._readbucketproxy.get_crypttext_hashes() - d.addCallback(self._validate) - return d - -class ValidatedExtendedURIProxy: - implements(IValidatedThingProxy) - """ I am a front-end for a remote UEB (using a local ReadBucketProxy), - responsible for retrieving and validating the elements from the UEB.""" - - def __init__(self, readbucketproxy, verifycap, fetch_failures=None): - # fetch_failures is for debugging -- see test_encode.py - self._fetch_failures = fetch_failures - self._readbucketproxy = readbucketproxy - precondition(IVerifierURI.providedBy(verifycap), verifycap) - self._verifycap = verifycap - - # required - self.segment_size = None - self.crypttext_root_hash = None - self.share_root_hash = None - - # computed - self.block_size = None - self.share_size = None - self.num_segments = None - self.tail_data_size = None - self.tail_segment_size = None - - # optional - self.crypttext_hash = None - - def __str__(self): - return "<%s %s>" % (self.__class__.__name__, self._verifycap.to_string()) - - def _check_integrity(self, data): - h = hashutil.uri_extension_hash(data) - if h != self._verifycap.uri_extension_hash: - msg = ("The copy of uri_extension we received from %s was bad: wanted %s, got %s" % - (self._readbucketproxy, - base32.b2a(self._verifycap.uri_extension_hash), - base32.b2a(h))) - if self._fetch_failures is not None: - self._fetch_failures["uri_extension"] += 1 - raise BadURIExtensionHashValue(msg) - else: - return data - - def _parse_and_validate(self, data): - self.share_size = mathutil.div_ceil(self._verifycap.size, - self._verifycap.needed_shares) - - d = uri.unpack_extension(data) - - # There are several kinds of things that can be found in a UEB. - # First, things that we really need to learn from the UEB in order to - # do this download. Next: things which are optional but not redundant - # -- if they are present in the UEB they will get used. Next, things - # that are optional and redundant. These things are required to be - # consistent: they don't have to be in the UEB, but if they are in - # the UEB then they will be checked for consistency with the - # already-known facts, and if they are inconsistent then an exception - # will be raised. These things aren't actually used -- they are just - # tested for consistency and ignored. Finally: things which are - # deprecated -- they ought not be in the UEB at all, and if they are - # present then a warning will be logged but they are otherwise - # ignored. - - # First, things that we really need to learn from the UEB: - # segment_size, crypttext_root_hash, and share_root_hash. - self.segment_size = d['segment_size'] - - self.block_size = mathutil.div_ceil(self.segment_size, - self._verifycap.needed_shares) - self.num_segments = mathutil.div_ceil(self._verifycap.size, - self.segment_size) - - self.tail_data_size = self._verifycap.size % self.segment_size - if not self.tail_data_size: - self.tail_data_size = self.segment_size - # padding for erasure code - self.tail_segment_size = mathutil.next_multiple(self.tail_data_size, - self._verifycap.needed_shares) - - # Ciphertext hash tree root is mandatory, so that there is at most - # one ciphertext that matches this read-cap or verify-cap. The - # integrity check on the shares is not sufficient to prevent the - # original encoder from creating some shares of file A and other - # shares of file B. - self.crypttext_root_hash = d['crypttext_root_hash'] - - self.share_root_hash = d['share_root_hash'] - - - # Next: things that are optional and not redundant: crypttext_hash - if d.has_key('crypttext_hash'): - self.crypttext_hash = d['crypttext_hash'] - if len(self.crypttext_hash) != hashutil.CRYPTO_VAL_SIZE: - raise BadURIExtension('crypttext_hash is required to be hashutil.CRYPTO_VAL_SIZE bytes, not %s bytes' % (len(self.crypttext_hash),)) - - - # Next: things that are optional, redundant, and required to be - # consistent: codec_name, codec_params, tail_codec_params, - # num_segments, size, needed_shares, total_shares - if d.has_key('codec_name'): - if d['codec_name'] != "crs": - raise UnsupportedErasureCodec(d['codec_name']) - - if d.has_key('codec_params'): - ucpss, ucpns, ucpts = codec.parse_params(d['codec_params']) - if ucpss != self.segment_size: - raise BadURIExtension("inconsistent erasure code params: " - "ucpss: %s != self.segment_size: %s" % - (ucpss, self.segment_size)) - if ucpns != self._verifycap.needed_shares: - raise BadURIExtension("inconsistent erasure code params: ucpns: %s != " - "self._verifycap.needed_shares: %s" % - (ucpns, self._verifycap.needed_shares)) - if ucpts != self._verifycap.total_shares: - raise BadURIExtension("inconsistent erasure code params: ucpts: %s != " - "self._verifycap.total_shares: %s" % - (ucpts, self._verifycap.total_shares)) - - if d.has_key('tail_codec_params'): - utcpss, utcpns, utcpts = codec.parse_params(d['tail_codec_params']) - if utcpss != self.tail_segment_size: - raise BadURIExtension("inconsistent erasure code params: utcpss: %s != " - "self.tail_segment_size: %s, self._verifycap.size: %s, " - "self.segment_size: %s, self._verifycap.needed_shares: %s" - % (utcpss, self.tail_segment_size, self._verifycap.size, - self.segment_size, self._verifycap.needed_shares)) - if utcpns != self._verifycap.needed_shares: - raise BadURIExtension("inconsistent erasure code params: utcpns: %s != " - "self._verifycap.needed_shares: %s" % (utcpns, - self._verifycap.needed_shares)) - if utcpts != self._verifycap.total_shares: - raise BadURIExtension("inconsistent erasure code params: utcpts: %s != " - "self._verifycap.total_shares: %s" % (utcpts, - self._verifycap.total_shares)) - - if d.has_key('num_segments'): - if d['num_segments'] != self.num_segments: - raise BadURIExtension("inconsistent num_segments: size: %s, " - "segment_size: %s, computed_num_segments: %s, " - "ueb_num_segments: %s" % (self._verifycap.size, - self.segment_size, - self.num_segments, d['num_segments'])) - - if d.has_key('size'): - if d['size'] != self._verifycap.size: - raise BadURIExtension("inconsistent size: URI size: %s, UEB size: %s" % - (self._verifycap.size, d['size'])) - - if d.has_key('needed_shares'): - if d['needed_shares'] != self._verifycap.needed_shares: - raise BadURIExtension("inconsistent needed shares: URI needed shares: %s, UEB " - "needed shares: %s" % (self._verifycap.total_shares, - d['needed_shares'])) - - if d.has_key('total_shares'): - if d['total_shares'] != self._verifycap.total_shares: - raise BadURIExtension("inconsistent total shares: URI total shares: %s, UEB " - "total shares: %s" % (self._verifycap.total_shares, - d['total_shares'])) - - # Finally, things that are deprecated and ignored: plaintext_hash, - # plaintext_root_hash - if d.get('plaintext_hash'): - log.msg("Found plaintext_hash in UEB. This field is deprecated for security reasons " - "and is no longer used. Ignoring. %s" % (self,)) - if d.get('plaintext_root_hash'): - log.msg("Found plaintext_root_hash in UEB. This field is deprecated for security " - "reasons and is no longer used. Ignoring. %s" % (self,)) - - return self - - def start(self): - """Fetch the UEB from bucket, compare its hash to the hash from - verifycap, then parse it. Returns a deferred which is called back - with self once the fetch is successful, or is erred back if it - fails.""" - d = self._readbucketproxy.get_uri_extension() - d.addCallback(self._check_integrity) - d.addCallback(self._parse_and_validate) - return d - -class ValidatedReadBucketProxy(log.PrefixingLogMixin): - """I am a front-end for a remote storage bucket, responsible for - retrieving and validating data from that bucket. - - My get_block() method is used by BlockDownloaders. - """ - - def __init__(self, sharenum, bucket, share_hash_tree, num_blocks, - block_size, share_size): - """ share_hash_tree is required to have already been initialized with - the root hash (the number-0 hash), using the share_root_hash from the - UEB""" - precondition(share_hash_tree[0] is not None, share_hash_tree) - prefix = "%d-%s-%s" % (sharenum, bucket, - base32.b2a_l(share_hash_tree[0][:8], 60)) - log.PrefixingLogMixin.__init__(self, - facility="tahoe.immutable.download", - prefix=prefix) - self.sharenum = sharenum - self.bucket = bucket - self.share_hash_tree = share_hash_tree - self.num_blocks = num_blocks - self.block_size = block_size - self.share_size = share_size - self.block_hash_tree = hashtree.IncompleteHashTree(self.num_blocks) - - def get_all_sharehashes(self): - """Retrieve and validate all the share-hash-tree nodes that are - included in this share, regardless of whether we need them to - validate the share or not. Each share contains a minimal Merkle tree - chain, but there is lots of overlap, so usually we'll be using hashes - from other shares and not reading every single hash from this share. - The Verifier uses this function to read and validate every single - hash from this share. - - Call this (and wait for the Deferred it returns to fire) before - calling get_block() for the first time: this lets us check that the - share share contains enough hashes to validate its own data, and - avoids downloading any share hash twice. - - I return a Deferred which errbacks upon failure, probably with - BadOrMissingHash.""" - - d = self.bucket.get_share_hashes() - def _got_share_hashes(sh): - sharehashes = dict(sh) - try: - self.share_hash_tree.set_hashes(sharehashes) - except IndexError, le: - raise BadOrMissingHash(le) - except (hashtree.BadHashError, hashtree.NotEnoughHashesError), le: - raise BadOrMissingHash(le) - d.addCallback(_got_share_hashes) - return d - - def get_all_blockhashes(self): - """Retrieve and validate all the block-hash-tree nodes that are - included in this share. Each share contains a full Merkle tree, but - we usually only fetch the minimal subset necessary for any particular - block. This function fetches everything at once. The Verifier uses - this function to validate the block hash tree. - - Call this (and wait for the Deferred it returns to fire) after - calling get_all_sharehashes() and before calling get_block() for the - first time: this lets us check that the share contains all block - hashes and avoids downloading them multiple times. - - I return a Deferred which errbacks upon failure, probably with - BadOrMissingHash. - """ - - # get_block_hashes(anything) currently always returns everything - needed = list(range(len(self.block_hash_tree))) - d = self.bucket.get_block_hashes(needed) - def _got_block_hashes(blockhashes): - if len(blockhashes) < len(self.block_hash_tree): - raise BadOrMissingHash() - bh = dict(enumerate(blockhashes)) - - try: - self.block_hash_tree.set_hashes(bh) - except IndexError, le: - raise BadOrMissingHash(le) - except (hashtree.BadHashError, hashtree.NotEnoughHashesError), le: - raise BadOrMissingHash(le) - d.addCallback(_got_block_hashes) - return d - - def get_all_crypttext_hashes(self, crypttext_hash_tree): - """Retrieve and validate all the crypttext-hash-tree nodes that are - in this share. Normally we don't look at these at all: the download - process fetches them incrementally as needed to validate each segment - of ciphertext. But this is a convenient place to give the Verifier a - function to validate all of these at once. - - Call this with a new hashtree object for each share, initialized with - the crypttext hash tree root. I return a Deferred which errbacks upon - failure, probably with BadOrMissingHash. - """ - - # get_crypttext_hashes() always returns everything - d = self.bucket.get_crypttext_hashes() - def _got_crypttext_hashes(hashes): - if len(hashes) < len(crypttext_hash_tree): - raise BadOrMissingHash() - ct_hashes = dict(enumerate(hashes)) - try: - crypttext_hash_tree.set_hashes(ct_hashes) - except IndexError, le: - raise BadOrMissingHash(le) - except (hashtree.BadHashError, hashtree.NotEnoughHashesError), le: - raise BadOrMissingHash(le) - d.addCallback(_got_crypttext_hashes) - return d - - def get_block(self, blocknum): - # the first time we use this bucket, we need to fetch enough elements - # of the share hash tree to validate it from our share hash up to the - # hashroot. - if self.share_hash_tree.needed_hashes(self.sharenum): - d1 = self.bucket.get_share_hashes() - else: - d1 = defer.succeed([]) - - # We might need to grab some elements of our block hash tree, to - # validate the requested block up to the share hash. - blockhashesneeded = self.block_hash_tree.needed_hashes(blocknum, include_leaf=True) - # We don't need the root of the block hash tree, as that comes in the - # share tree. - blockhashesneeded.discard(0) - d2 = self.bucket.get_block_hashes(blockhashesneeded) - - if blocknum < self.num_blocks-1: - thisblocksize = self.block_size - else: - thisblocksize = self.share_size % self.block_size - if thisblocksize == 0: - thisblocksize = self.block_size - d3 = self.bucket.get_block_data(blocknum, - self.block_size, thisblocksize) - - dl = deferredutil.gatherResults([d1, d2, d3]) - dl.addCallback(self._got_data, blocknum) - return dl - - def _got_data(self, results, blocknum): - precondition(blocknum < self.num_blocks, - self, blocknum, self.num_blocks) - sharehashes, blockhashes, blockdata = results - try: - sharehashes = dict(sharehashes) - except ValueError, le: - le.args = tuple(le.args + (sharehashes,)) - raise - blockhashes = dict(enumerate(blockhashes)) - - candidate_share_hash = None # in case we log it in the except block below - blockhash = None # in case we log it in the except block below - - try: - if self.share_hash_tree.needed_hashes(self.sharenum): - # This will raise exception if the values being passed do not - # match the root node of self.share_hash_tree. - try: - self.share_hash_tree.set_hashes(sharehashes) - except IndexError, le: - # Weird -- sharehashes contained index numbers outside of - # the range that fit into this hash tree. - raise BadOrMissingHash(le) - - # To validate a block we need the root of the block hash tree, - # which is also one of the leafs of the share hash tree, and is - # called "the share hash". - if not self.block_hash_tree[0]: # empty -- no root node yet - # Get the share hash from the share hash tree. - share_hash = self.share_hash_tree.get_leaf(self.sharenum) - if not share_hash: - # No root node in block_hash_tree and also the share hash - # wasn't sent by the server. - raise hashtree.NotEnoughHashesError - self.block_hash_tree.set_hashes({0: share_hash}) - - if self.block_hash_tree.needed_hashes(blocknum): - self.block_hash_tree.set_hashes(blockhashes) - - blockhash = hashutil.block_hash(blockdata) - self.block_hash_tree.set_hashes(leaves={blocknum: blockhash}) - #self.log("checking block_hash(shareid=%d, blocknum=%d) len=%d " - # "%r .. %r: %s" % - # (self.sharenum, blocknum, len(blockdata), - # blockdata[:50], blockdata[-50:], base32.b2a(blockhash))) - - except (hashtree.BadHashError, hashtree.NotEnoughHashesError), le: - # log.WEIRD: indicates undetected disk/network error, or more - # likely a programming error - self.log("hash failure in block=%d, shnum=%d on %s" % - (blocknum, self.sharenum, self.bucket)) - if self.block_hash_tree.needed_hashes(blocknum): - self.log(""" failure occurred when checking the block_hash_tree. - This suggests that either the block data was bad, or that the - block hashes we received along with it were bad.""") - else: - self.log(""" the failure probably occurred when checking the - share_hash_tree, which suggests that the share hashes we - received from the remote peer were bad.""") - self.log(" have candidate_share_hash: %s" % bool(candidate_share_hash)) - self.log(" block length: %d" % len(blockdata)) - self.log(" block hash: %s" % base32.b2a_or_none(blockhash)) - if len(blockdata) < 100: - self.log(" block data: %r" % (blockdata,)) - else: - self.log(" block data start/end: %r .. %r" % - (blockdata[:50], blockdata[-50:])) - self.log(" share hash tree:\n" + self.share_hash_tree.dump()) - self.log(" block hash tree:\n" + self.block_hash_tree.dump()) - lines = [] - for i,h in sorted(sharehashes.items()): - lines.append("%3d: %s" % (i, base32.b2a_or_none(h))) - self.log(" sharehashes:\n" + "\n".join(lines) + "\n") - lines = [] - for i,h in blockhashes.items(): - lines.append("%3d: %s" % (i, base32.b2a_or_none(h))) - log.msg(" blockhashes:\n" + "\n".join(lines) + "\n") - raise BadOrMissingHash(le) - - # If we made it here, the block is good. If the hash trees didn't - # like what they saw, they would have raised a BadHashError, causing - # our caller to see a Failure and thus ignore this block (as well as - # dropping this bucket). - return blockdata - - - -class BlockDownloader(log.PrefixingLogMixin): - """I am responsible for downloading a single block (from a single bucket) - for a single segment. - - I am a child of the SegmentDownloader. - """ - - def __init__(self, vbucket, blocknum, parent, results): - precondition(isinstance(vbucket, ValidatedReadBucketProxy), vbucket) - prefix = "%s-%d" % (vbucket, blocknum) - log.PrefixingLogMixin.__init__(self, facility="tahoe.immutable.download", prefix=prefix) - self.vbucket = vbucket - self.blocknum = blocknum - self.parent = parent - self.results = results - - def start(self, segnum): - self.log("get_block(segnum=%d)" % segnum) - started = time.time() - d = self.vbucket.get_block(segnum) - d.addCallbacks(self._hold_block, self._got_block_error, - callbackArgs=(started,)) - return d - - def _hold_block(self, data, started): - if self.results: - elapsed = time.time() - started - peerid = self.vbucket.bucket.get_peerid() - if peerid not in self.results.timings["fetch_per_server"]: - self.results.timings["fetch_per_server"][peerid] = [] - self.results.timings["fetch_per_server"][peerid].append(elapsed) - self.log("got block") - self.parent.hold_block(self.blocknum, data) - - def _got_block_error(self, f): - f.trap(RemoteException, DeadReferenceError, - IntegrityCheckReject, layout.LayoutInvalid, - layout.ShareVersionIncompatible) - if f.check(RemoteException, DeadReferenceError): - level = log.UNUSUAL - else: - level = log.WEIRD - self.log("failure to get block", level=level, umid="5Z4uHQ") - if self.results: - peerid = self.vbucket.bucket.get_peerid() - self.results.server_problems[peerid] = str(f) - self.parent.bucket_failed(self.vbucket) - -class SegmentDownloader: - """I am responsible for downloading all the blocks for a single segment - of data. - - I am a child of the CiphertextDownloader. - """ - - def __init__(self, parent, segmentnumber, needed_shares, results): - self.parent = parent - self.segmentnumber = segmentnumber - self.needed_blocks = needed_shares - self.blocks = {} # k: blocknum, v: data - self.results = results - self._log_number = self.parent.log("starting segment %d" % - segmentnumber) - - def log(self, *args, **kwargs): - if "parent" not in kwargs: - kwargs["parent"] = self._log_number - return self.parent.log(*args, **kwargs) - - def start(self): - return self._download() - - def _download(self): - d = self._try() - def _done(res): - if len(self.blocks) >= self.needed_blocks: - # we only need self.needed_blocks blocks - # we want to get the smallest blockids, because they are - # more likely to be fast "primary blocks" - blockids = sorted(self.blocks.keys())[:self.needed_blocks] - blocks = [] - for blocknum in blockids: - blocks.append(self.blocks[blocknum]) - return (blocks, blockids) - else: - return self._download() - d.addCallback(_done) - return d - - def _try(self): - # fill our set of active buckets, maybe raising NotEnoughSharesError - active_buckets = self.parent._activate_enough_buckets() - # Now we have enough buckets, in self.parent.active_buckets. - - # in test cases, bd.start might mutate active_buckets right away, so - # we need to put off calling start() until we've iterated all the way - # through it. - downloaders = [] - for blocknum, vbucket in active_buckets.iteritems(): - assert isinstance(vbucket, ValidatedReadBucketProxy), vbucket - bd = BlockDownloader(vbucket, blocknum, self, self.results) - downloaders.append(bd) - if self.results: - self.results.servers_used.add(vbucket.bucket.get_peerid()) - l = [bd.start(self.segmentnumber) for bd in downloaders] - return defer.DeferredList(l, fireOnOneErrback=True) - - def hold_block(self, blocknum, data): - self.blocks[blocknum] = data - - def bucket_failed(self, vbucket): - self.parent.bucket_failed(vbucket) - -class DownloadStatus: - implements(IDownloadStatus) - statusid_counter = itertools.count(0) - - def __init__(self): - self.storage_index = None - self.size = None - self.helper = False - self.status = "Not started" - self.progress = 0.0 - self.paused = False - self.stopped = False - self.active = True - self.results = None - self.counter = self.statusid_counter.next() - self.started = time.time() - - def get_started(self): - return self.started - def get_storage_index(self): - return self.storage_index - def get_size(self): - return self.size - def using_helper(self): - return self.helper - def get_status(self): - status = self.status - if self.paused: - status += " (output paused)" - if self.stopped: - status += " (output stopped)" - return status - def get_progress(self): - return self.progress - def get_active(self): - return self.active - def get_results(self): - return self.results - def get_counter(self): - return self.counter - - def set_storage_index(self, si): - self.storage_index = si - def set_size(self, size): - self.size = size - def set_helper(self, helper): - self.helper = helper - def set_status(self, status): - self.status = status - def set_paused(self, paused): - self.paused = paused - def set_stopped(self, stopped): - self.stopped = stopped - def set_progress(self, value): - self.progress = value - def set_active(self, value): - self.active = value - def set_results(self, value): - self.results = value - -class CiphertextDownloader(log.PrefixingLogMixin): - """ I download shares, check their integrity, then decode them, check the - integrity of the resulting ciphertext, then and write it to my target. - Before I send any new request to a server, I always ask the 'monitor' - object that was passed into my constructor whether this task has been - cancelled (by invoking its raise_if_cancelled() method).""" - implements(IPushProducer) - _status = None - - def __init__(self, storage_broker, v, target, monitor): - - precondition(IStorageBroker.providedBy(storage_broker), storage_broker) - precondition(IVerifierURI.providedBy(v), v) - precondition(IDownloadTarget.providedBy(target), target) - - self._storage_broker = storage_broker - self._verifycap = v - self._storage_index = v.get_storage_index() - self._uri_extension_hash = v.uri_extension_hash - - prefix=base32.b2a_l(self._storage_index[:8], 60) - log.PrefixingLogMixin.__init__(self, facility="tahoe.immutable.download", prefix=prefix) - - self._started = time.time() - self._status = s = DownloadStatus() - s.set_status("Starting") - s.set_storage_index(self._storage_index) - s.set_size(self._verifycap.size) - s.set_helper(False) - s.set_active(True) - - self._results = DownloadResults() - s.set_results(self._results) - self._results.file_size = self._verifycap.size - self._results.timings["servers_peer_selection"] = {} - self._results.timings["fetch_per_server"] = {} - self._results.timings["cumulative_fetch"] = 0.0 - self._results.timings["cumulative_decode"] = 0.0 - self._results.timings["cumulative_decrypt"] = 0.0 - self._results.timings["paused"] = 0.0 - - self._paused = False - self._stopped = False - if IConsumer.providedBy(target): - target.registerProducer(self, True) - self._target = target - # Repairer (uploader) needs the storageindex. - self._target.set_storageindex(self._storage_index) - self._monitor = monitor - self._opened = False - - self.active_buckets = {} # k: shnum, v: bucket - self._share_buckets = {} # k: sharenum, v: list of buckets - - # _download_all_segments() will set this to: - # self._share_vbuckets = {} # k: shnum, v: set of ValidatedBuckets - self._share_vbuckets = None - - self._fetch_failures = {"uri_extension": 0, "crypttext_hash_tree": 0, } - - self._ciphertext_hasher = hashutil.crypttext_hasher() - - self._bytes_done = 0 - self._status.set_progress(float(self._bytes_done)/self._verifycap.size) - - # _got_uri_extension() will create the following: - # self._crypttext_hash_tree - # self._share_hash_tree - # self._current_segnum = 0 - # self._vup # ValidatedExtendedURIProxy - - # _get_all_shareholders() will create the following: - # self._total_queries - # self._responses_received = 0 - # self._queries_failed = 0 - - # This is solely for the use of unit tests. It will be triggered when - # we start downloading shares. - self._stage_4_d = defer.Deferred() - - def pauseProducing(self): - if self._paused: - return - self._paused = defer.Deferred() - self._paused_at = time.time() - if self._status: - self._status.set_paused(True) - - def resumeProducing(self): - if self._paused: - paused_for = time.time() - self._paused_at - self._results.timings['paused'] += paused_for - p = self._paused - self._paused = None - eventually(p.callback, None) - if self._status: - self._status.set_paused(False) - - def stopProducing(self): - self.log("Download.stopProducing") - self._stopped = True - self.resumeProducing() - if self._status: - self._status.set_stopped(True) - self._status.set_active(False) - - def start(self): - self.log("starting download") - - # first step: who should we download from? - d = defer.maybeDeferred(self._get_all_shareholders) - d.addBoth(self._got_all_shareholders) - # now get the uri_extension block from somebody and integrity check - # it and parse and validate its contents - d.addCallback(self._obtain_uri_extension) - d.addCallback(self._get_crypttext_hash_tree) - # once we know that, we can download blocks from everybody - d.addCallback(self._download_all_segments) - def _finished(res): - if self._status: - self._status.set_status("Finished") - self._status.set_active(False) - self._status.set_paused(False) - if IConsumer.providedBy(self._target): - self._target.unregisterProducer() - return res - d.addBoth(_finished) - def _failed(why): - if self._status: - self._status.set_status("Failed") - self._status.set_active(False) - if why.check(DownloadStopped): - # DownloadStopped just means the consumer aborted the - # download; not so scary. - self.log("download stopped", level=log.UNUSUAL) - else: - # This is really unusual, and deserves maximum forensics. - self.log("download failed!", failure=why, level=log.SCARY, - umid="lp1vaQ") - return why - d.addErrback(_failed) - d.addCallback(self._done) - return d - - def _get_all_shareholders(self): - """ Once the number of buckets that I know about is >= K then I - callback the Deferred that I return. - - If all of the get_buckets deferreds have fired (whether callback - or errback) and I still don't have enough buckets then I'll also - callback -- not errback -- the Deferred that I return. - """ - wait_for_enough_buckets_d = defer.Deferred() - self._wait_for_enough_buckets_d = wait_for_enough_buckets_d - - sb = self._storage_broker - servers = sb.get_servers_for_index(self._storage_index) - if not servers: - raise NoServersError("broker gave us no servers!") - - self._total_queries = len(servers) - self._responses_received = 0 - self._queries_failed = 0 - for (peerid,ss) in servers: - self.log(format="sending DYHB to [%(peerid)s]", - peerid=idlib.shortnodeid_b2a(peerid), - level=log.NOISY, umid="rT03hg") - d = ss.callRemote("get_buckets", self._storage_index) - d.addCallbacks(self._got_response, self._got_error, - callbackArgs=(peerid,)) - d.addBoth(self._check_got_all_responses) - - if self._status: - self._status.set_status("Locating Shares (%d/%d)" % - (self._responses_received, - self._total_queries)) - return wait_for_enough_buckets_d - - def _check_got_all_responses(self, ignored=None): - assert (self._responses_received+self._queries_failed) <= self._total_queries - if self._wait_for_enough_buckets_d and (self._responses_received+self._queries_failed) == self._total_queries: - reactor.callLater(0, self._wait_for_enough_buckets_d.callback, False) - self._wait_for_enough_buckets_d = None - - def _got_response(self, buckets, peerid): - # Note that this can continue to receive responses after _wait_for_enough_buckets_d - # has fired. - self._responses_received += 1 - self.log(format="got results from [%(peerid)s]: shnums %(shnums)s", - peerid=idlib.shortnodeid_b2a(peerid), - shnums=sorted(buckets.keys()), - level=log.NOISY, umid="o4uwFg") - if self._results: - elapsed = time.time() - self._started - self._results.timings["servers_peer_selection"][peerid] = elapsed - if self._status: - self._status.set_status("Locating Shares (%d/%d)" % - (self._responses_received, - self._total_queries)) - for sharenum, bucket in buckets.iteritems(): - b = layout.ReadBucketProxy(bucket, peerid, self._storage_index) - self.add_share_bucket(sharenum, b) - # If we just got enough buckets for the first time, then fire the - # deferred. Then remove it from self so that we don't fire it - # again. - if self._wait_for_enough_buckets_d and len(self._share_buckets) >= self._verifycap.needed_shares: - reactor.callLater(0, self._wait_for_enough_buckets_d.callback, True) - self._wait_for_enough_buckets_d = None - - if self._share_vbuckets is not None: - vbucket = ValidatedReadBucketProxy(sharenum, b, self._share_hash_tree, self._vup.num_segments, self._vup.block_size, self._vup.share_size) - self._share_vbuckets.setdefault(sharenum, set()).add(vbucket) - - if self._results: - if peerid not in self._results.servermap: - self._results.servermap[peerid] = set() - self._results.servermap[peerid].add(sharenum) - - def add_share_bucket(self, sharenum, bucket): - # this is split out for the benefit of test_encode.py - self._share_buckets.setdefault(sharenum, []).append(bucket) - - def _got_error(self, f): - self._queries_failed += 1 - level = log.WEIRD - if f.check(DeadReferenceError): - level = log.UNUSUAL - self.log("Error during get_buckets", failure=f, level=level, - umid="3uuBUQ") - - def bucket_failed(self, vbucket): - shnum = vbucket.sharenum - del self.active_buckets[shnum] - s = self._share_vbuckets[shnum] - # s is a set of ValidatedReadBucketProxy instances - s.remove(vbucket) - # ... which might now be empty - if not s: - # there are no more buckets which can provide this share, so - # remove the key. This may prompt us to use a different share. - del self._share_vbuckets[shnum] - - def _got_all_shareholders(self, res): - if self._results: - now = time.time() - self._results.timings["peer_selection"] = now - self._started - - if len(self._share_buckets) < self._verifycap.needed_shares: - msg = "Failed to get enough shareholders: have %d, need %d" \ - % (len(self._share_buckets), self._verifycap.needed_shares) - if self._share_buckets: - raise NotEnoughSharesError(msg) - else: - raise NoSharesError(msg) - - #for s in self._share_vbuckets.values(): - # for vb in s: - # assert isinstance(vb, ValidatedReadBucketProxy), \ - # "vb is %s but should be a ValidatedReadBucketProxy" % (vb,) - - def _obtain_uri_extension(self, ignored): - # all shareholders are supposed to have a copy of uri_extension, and - # all are supposed to be identical. We compute the hash of the data - # that comes back, and compare it against the version in our URI. If - # they don't match, ignore their data and try someone else. - if self._status: - self._status.set_status("Obtaining URI Extension") - - uri_extension_fetch_started = time.time() - - vups = [] - for sharenum, buckets in self._share_buckets.iteritems(): - for bucket in buckets: - vups.append(ValidatedExtendedURIProxy(bucket, self._verifycap, self._fetch_failures)) - vto = ValidatedThingObtainer(vups, debugname="vups", log_id=self._parentmsgid) - d = vto.start() - - def _got_uri_extension(vup): - precondition(isinstance(vup, ValidatedExtendedURIProxy), vup) - if self._results: - elapsed = time.time() - uri_extension_fetch_started - self._results.timings["uri_extension"] = elapsed - - self._vup = vup - self._codec = codec.CRSDecoder() - self._codec.set_params(self._vup.segment_size, self._verifycap.needed_shares, self._verifycap.total_shares) - self._tail_codec = codec.CRSDecoder() - self._tail_codec.set_params(self._vup.tail_segment_size, self._verifycap.needed_shares, self._verifycap.total_shares) - - self._current_segnum = 0 - - self._share_hash_tree = hashtree.IncompleteHashTree(self._verifycap.total_shares) - self._share_hash_tree.set_hashes({0: vup.share_root_hash}) - - self._crypttext_hash_tree = hashtree.IncompleteHashTree(self._vup.num_segments) - self._crypttext_hash_tree.set_hashes({0: self._vup.crypttext_root_hash}) - - # Repairer (uploader) needs the encodingparams. - self._target.set_encodingparams(( - self._verifycap.needed_shares, - 0, # see ticket #778 for why this is - self._verifycap.total_shares, - self._vup.segment_size - )) - d.addCallback(_got_uri_extension) - return d - - def _get_crypttext_hash_tree(self, res): - vchtps = [] - for sharenum, buckets in self._share_buckets.iteritems(): - for bucket in buckets: - vchtp = ValidatedCrypttextHashTreeProxy(bucket, self._crypttext_hash_tree, self._vup.num_segments, self._fetch_failures) - vchtps.append(vchtp) - - _get_crypttext_hash_tree_started = time.time() - if self._status: - self._status.set_status("Retrieving crypttext hash tree") - - vto = ValidatedThingObtainer(vchtps, debugname="vchtps", - log_id=self._parentmsgid) - d = vto.start() - - def _got_crypttext_hash_tree(res): - # Good -- the self._crypttext_hash_tree that we passed to vchtp - # is now populated with hashes. - if self._results: - elapsed = time.time() - _get_crypttext_hash_tree_started - self._results.timings["hashtrees"] = elapsed - d.addCallback(_got_crypttext_hash_tree) - return d - - def _activate_enough_buckets(self): - """either return a mapping from shnum to a ValidatedReadBucketProxy - that can provide data for that share, or raise NotEnoughSharesError""" - - while len(self.active_buckets) < self._verifycap.needed_shares: - # need some more - handled_shnums = set(self.active_buckets.keys()) - available_shnums = set(self._share_vbuckets.keys()) - potential_shnums = list(available_shnums - handled_shnums) - if len(potential_shnums) < (self._verifycap.needed_shares - - len(self.active_buckets)): - have = len(potential_shnums) + len(self.active_buckets) - msg = "Unable to activate enough shares: have %d, need %d" \ - % (have, self._verifycap.needed_shares) - if have: - raise NotEnoughSharesError(msg) - else: - raise NoSharesError(msg) - # For the next share, choose a primary share if available, else a - # randomly chosen secondary share. - potential_shnums.sort() - if potential_shnums[0] < self._verifycap.needed_shares: - shnum = potential_shnums[0] - else: - shnum = random.choice(potential_shnums) - # and a random bucket that will provide it - validated_bucket = random.choice(list(self._share_vbuckets[shnum])) - self.active_buckets[shnum] = validated_bucket - return self.active_buckets - - - def _download_all_segments(self, res): - # From now on if new buckets are received then I will notice that - # self._share_vbuckets is not None and generate a vbucket for that new - # bucket and add it in to _share_vbuckets. (We had to wait because we - # didn't have self._vup and self._share_hash_tree earlier. We didn't - # need validated buckets until now -- now that we are ready to download - # shares.) - self._share_vbuckets = {} - for sharenum, buckets in self._share_buckets.iteritems(): - for bucket in buckets: - vbucket = ValidatedReadBucketProxy(sharenum, bucket, self._share_hash_tree, self._vup.num_segments, self._vup.block_size, self._vup.share_size) - self._share_vbuckets.setdefault(sharenum, set()).add(vbucket) - - # after the above code, self._share_vbuckets contains enough - # buckets to complete the download, and some extra ones to - # tolerate some buckets dropping out or having - # errors. self._share_vbuckets is a dictionary that maps from - # shnum to a set of ValidatedBuckets, which themselves are - # wrappers around RIBucketReader references. - self.active_buckets = {} # k: shnum, v: ValidatedReadBucketProxy instance - - self._started_fetching = time.time() - - d = defer.succeed(None) - for segnum in range(self._vup.num_segments): - d.addCallback(self._download_segment, segnum) - # this pause, at the end of write, prevents pre-fetch from - # happening until the consumer is ready for more data. - d.addCallback(self._check_for_pause) - - self._stage_4_d.callback(None) - return d - - def _check_for_pause(self, res): - if self._paused: - d = defer.Deferred() - self._paused.addCallback(lambda ignored: d.callback(res)) - return d - if self._stopped: - raise DownloadStopped("our Consumer called stopProducing()") - self._monitor.raise_if_cancelled() - return res - - def _download_segment(self, res, segnum): - if self._status: - self._status.set_status("Downloading segment %d of %d" % - (segnum+1, self._vup.num_segments)) - self.log("downloading seg#%d of %d (%d%%)" - % (segnum, self._vup.num_segments, - 100.0 * segnum / self._vup.num_segments)) - # memory footprint: when the SegmentDownloader finishes pulling down - # all shares, we have 1*segment_size of usage. - segmentdler = SegmentDownloader(self, segnum, - self._verifycap.needed_shares, - self._results) - started = time.time() - d = segmentdler.start() - def _finished_fetching(res): - elapsed = time.time() - started - self._results.timings["cumulative_fetch"] += elapsed - return res - if self._results: - d.addCallback(_finished_fetching) - # pause before using more memory - d.addCallback(self._check_for_pause) - # while the codec does its job, we hit 2*segment_size - def _started_decode(res): - self._started_decode = time.time() - return res - if self._results: - d.addCallback(_started_decode) - if segnum + 1 == self._vup.num_segments: - codec = self._tail_codec - else: - codec = self._codec - d.addCallback(lambda (shares, shareids): codec.decode(shares, shareids)) - # once the codec is done, we drop back to 1*segment_size, because - # 'shares' goes out of scope. The memory usage is all in the - # plaintext now, spread out into a bunch of tiny buffers. - def _finished_decode(res): - elapsed = time.time() - self._started_decode - self._results.timings["cumulative_decode"] += elapsed - return res - if self._results: - d.addCallback(_finished_decode) - - # pause/check-for-stop just before writing, to honor stopProducing - d.addCallback(self._check_for_pause) - d.addCallback(self._got_segment) - return d - - def _got_segment(self, buffers): - precondition(self._crypttext_hash_tree) - started_decrypt = time.time() - self._status.set_progress(float(self._current_segnum)/self._verifycap.size) - - if self._current_segnum + 1 == self._vup.num_segments: - # This is the last segment. - # Trim off any padding added by the upload side. We never send - # empty segments. If the data was an exact multiple of the - # segment size, the last segment will be full. - tail_buf_size = mathutil.div_ceil(self._vup.tail_segment_size, self._verifycap.needed_shares) - num_buffers_used = mathutil.div_ceil(self._vup.tail_data_size, tail_buf_size) - # Remove buffers which don't contain any part of the tail. - del buffers[num_buffers_used:] - # Remove the past-the-tail-part of the last buffer. - tail_in_last_buf = self._vup.tail_data_size % tail_buf_size - if tail_in_last_buf == 0: - tail_in_last_buf = tail_buf_size - buffers[-1] = buffers[-1][:tail_in_last_buf] - - # First compute the hash of this segment and check that it fits. - ch = hashutil.crypttext_segment_hasher() - for buffer in buffers: - self._ciphertext_hasher.update(buffer) - ch.update(buffer) - self._crypttext_hash_tree.set_hashes(leaves={self._current_segnum: ch.digest()}) - - # Then write this segment to the target. - if not self._opened: - self._opened = True - self._target.open(self._verifycap.size) - - for buffer in buffers: - self._target.write(buffer) - self._bytes_done += len(buffer) - - self._status.set_progress(float(self._bytes_done)/self._verifycap.size) - self._current_segnum += 1 - - if self._results: - elapsed = time.time() - started_decrypt - self._results.timings["cumulative_decrypt"] += elapsed - - def _done(self, res): - self.log("download done") - if self._results: - now = time.time() - self._results.timings["total"] = now - self._started - self._results.timings["segments"] = now - self._started_fetching - if self._vup.crypttext_hash: - _assert(self._vup.crypttext_hash == self._ciphertext_hasher.digest(), - "bad crypttext_hash: computed=%s, expected=%s" % - (base32.b2a(self._ciphertext_hasher.digest()), - base32.b2a(self._vup.crypttext_hash))) - _assert(self._bytes_done == self._verifycap.size, self._bytes_done, self._verifycap.size) - self._status.set_progress(1) - self._target.close() - return self._target.finish() - def get_download_status(self): - return self._status - - -class ConsumerAdapter: - implements(IDownloadTarget, IConsumer) - def __init__(self, consumer): - self._consumer = consumer - - def registerProducer(self, producer, streaming): - self._consumer.registerProducer(producer, streaming) - def unregisterProducer(self): - self._consumer.unregisterProducer() - - def open(self, size): - pass - def write(self, data): - self._consumer.write(data) - def close(self): - pass - - def fail(self, why): - pass - def register_canceller(self, cb): - pass - def finish(self): - return self._consumer - # The following methods are just because the target might be a - # repairer.DownUpConnector, and just because the current CHKUpload object - # expects to find the storage index and encoding parameters in its - # Uploadable. - def set_storageindex(self, storageindex): - pass - def set_encodingparams(self, encodingparams): - pass - - -class Downloader: - """I am a service that allows file downloading. - """ - # TODO: in fact, this service only downloads immutable files (URI:CHK:). - # It is scheduled to go away, to be replaced by filenode.download() - implements(IDownloader) - - def __init__(self, storage_broker, stats_provider): - self.storage_broker = storage_broker - self.stats_provider = stats_provider - self._all_downloads = weakref.WeakKeyDictionary() # for debugging - - def download(self, u, t, _log_msg_id=None, monitor=None, history=None): - assert isinstance(u, uri.CHKFileURI) - t = IDownloadTarget(t) - assert t.write - assert t.close - - if self.stats_provider: - # these counters are meant for network traffic, and don't - # include LIT files - self.stats_provider.count('downloader.files_downloaded', 1) - self.stats_provider.count('downloader.bytes_downloaded', u.get_size()) - - target = DecryptingTarget(t, u.key, _log_msg_id=_log_msg_id) - if not monitor: - monitor=Monitor() - dl = CiphertextDownloader(self.storage_broker, - u.get_verify_cap(), target, - monitor=monitor) - self._all_downloads[dl] = None - if history: - history.add_download(dl.get_download_status()) - d = dl.start() - return d diff --git a/src/allmydata/immutable/downloader/__init__.py b/src/allmydata/immutable/downloader/__init__.py new file mode 100644 index 00000000..e69de29b diff --git a/src/allmydata/immutable/downloader/common.py b/src/allmydata/immutable/downloader/common.py new file mode 100644 index 00000000..e9dd2719 --- /dev/null +++ b/src/allmydata/immutable/downloader/common.py @@ -0,0 +1,13 @@ + +(AVAILABLE, PENDING, OVERDUE, COMPLETE, CORRUPT, DEAD, BADSEGNUM) = \ + ("AVAILABLE", "PENDING", "OVERDUE", "COMPLETE", "CORRUPT", "DEAD", "BADSEGNUM") + +class BadSegmentNumberError(Exception): + pass +class WrongSegmentError(Exception): + pass +class BadCiphertextHashError(Exception): + pass + +class DownloadStopped(Exception): + pass diff --git a/src/allmydata/immutable/downloader/fetcher.py b/src/allmydata/immutable/downloader/fetcher.py new file mode 100644 index 00000000..3918f659 --- /dev/null +++ b/src/allmydata/immutable/downloader/fetcher.py @@ -0,0 +1,229 @@ + +from twisted.python.failure import Failure +from foolscap.api import eventually +from allmydata.interfaces import NotEnoughSharesError, NoSharesError +from allmydata.util import log +from allmydata.util.dictutil import DictOfSets +from common import AVAILABLE, PENDING, OVERDUE, COMPLETE, CORRUPT, DEAD, \ + BADSEGNUM, BadSegmentNumberError + +class SegmentFetcher: + """I am responsible for acquiring blocks for a single segment. I will use + the Share instances passed to my add_shares() method to locate, retrieve, + and validate those blocks. I expect my parent node to call my + no_more_shares() method when there are no more shares available. I will + call my parent's want_more_shares() method when I want more: I expect to + see at least one call to add_shares or no_more_shares afterwards. + + When I have enough validated blocks, I will call my parent's + process_blocks() method with a dictionary that maps shnum to blockdata. + If I am unable to provide enough blocks, I will call my parent's + fetch_failed() method with (self, f). After either of these events, I + will shut down and do no further work. My parent can also call my stop() + method to have me shut down early.""" + + def __init__(self, node, segnum, k): + self._node = node # _Node + self.segnum = segnum + self._k = k + self._shares = {} # maps non-dead Share instance to a state, one of + # (AVAILABLE, PENDING, OVERDUE, COMPLETE, CORRUPT). + # State transition map is: + # AVAILABLE -(send-read)-> PENDING + # PENDING -(timer)-> OVERDUE + # PENDING -(rx)-> COMPLETE, CORRUPT, DEAD, BADSEGNUM + # OVERDUE -(rx)-> COMPLETE, CORRUPT, DEAD, BADSEGNUM + # If a share becomes DEAD, it is removed from the + # dict. If it becomes BADSEGNUM, the whole fetch is + # terminated. + self._share_observers = {} # maps Share to EventStreamObserver for + # active ones + self._shnums = DictOfSets() # maps shnum to the shares that provide it + self._blocks = {} # maps shnum to validated block data + self._no_more_shares = False + self._bad_segnum = False + self._last_failure = None + self._running = True + + def stop(self): + log.msg("SegmentFetcher(%s).stop" % self._node._si_prefix, + level=log.NOISY, umid="LWyqpg") + self._cancel_all_requests() + self._running = False + self._shares.clear() # let GC work # ??? XXX + + + # called by our parent _Node + + def add_shares(self, shares): + # called when ShareFinder locates a new share, and when a non-initial + # segment fetch is started and we already know about shares from the + # previous segment + for s in shares: + self._shares[s] = AVAILABLE + self._shnums.add(s._shnum, s) + eventually(self.loop) + + def no_more_shares(self): + # ShareFinder tells us it's reached the end of its list + self._no_more_shares = True + eventually(self.loop) + + # internal methods + + def _count_shnums(self, *states): + """shnums for which at least one state is in the following list""" + shnums = [] + for shnum,shares in self._shnums.iteritems(): + matches = [s for s in shares if self._shares.get(s) in states] + if matches: + shnums.append(shnum) + return len(shnums) + + def loop(self): + try: + # if any exception occurs here, kill the download + self._do_loop() + except BaseException: + self._node.fetch_failed(self, Failure()) + raise + + def _do_loop(self): + k = self._k + if not self._running: + return + if self._bad_segnum: + # oops, we were asking for a segment number beyond the end of the + # file. This is an error. + self.stop() + e = BadSegmentNumberError("segnum=%d, numsegs=%d" % + (self.segnum, self._node.num_segments)) + f = Failure(e) + self._node.fetch_failed(self, f) + return + + # are we done? + if self._count_shnums(COMPLETE) >= k: + # yay! + self.stop() + self._node.process_blocks(self.segnum, self._blocks) + return + + # we may have exhausted everything + if (self._no_more_shares and + self._count_shnums(AVAILABLE, PENDING, OVERDUE, COMPLETE) < k): + # no more new shares are coming, and the remaining hopeful shares + # aren't going to be enough. boo! + + log.msg("share states: %r" % (self._shares,), + level=log.NOISY, umid="0ThykQ") + if self._count_shnums(AVAILABLE, PENDING, OVERDUE, COMPLETE) == 0: + format = ("no shares (need %(k)d)." + " Last failure: %(last_failure)s") + args = { "k": k, + "last_failure": self._last_failure } + error = NoSharesError + else: + format = ("ran out of shares: %(complete)d complete," + " %(pending)d pending, %(overdue)d overdue," + " %(unused)d unused, need %(k)d." + " Last failure: %(last_failure)s") + args = {"complete": self._count_shnums(COMPLETE), + "pending": self._count_shnums(PENDING), + "overdue": self._count_shnums(OVERDUE), + # 'unused' should be zero + "unused": self._count_shnums(AVAILABLE), + "k": k, + "last_failure": self._last_failure, + } + error = NotEnoughSharesError + log.msg(format=format, level=log.UNUSUAL, umid="1DsnTg", **args) + e = error(format % args) + f = Failure(e) + self.stop() + self._node.fetch_failed(self, f) + return + + # nope, not done. Are we "block-hungry" (i.e. do we want to send out + # more read requests, or do we think we have enough in flight + # already?) + while self._count_shnums(PENDING, COMPLETE) < k: + # we're hungry.. are there any unused shares? + sent = self._send_new_request() + if not sent: + break + + # ok, now are we "share-hungry" (i.e. do we have enough known shares + # to make us happy, or should we ask the ShareFinder to get us more?) + if self._count_shnums(AVAILABLE, PENDING, COMPLETE) < k: + # we're hungry for more shares + self._node.want_more_shares() + # that will trigger the ShareFinder to keep looking + + def _find_one(self, shares, state): + # TODO could choose fastest + for s in shares: + if self._shares[s] == state: + return s + # can never get here, caller has assert in case of code bug + + def _send_new_request(self): + for shnum,shares in sorted(self._shnums.iteritems()): + states = [self._shares[s] for s in shares] + if COMPLETE in states or PENDING in states: + # don't send redundant requests + continue + if AVAILABLE not in states: + # no candidates for this shnum, move on + continue + # here's a candidate. Send a request. + s = self._find_one(shares, AVAILABLE) + assert s + self._shares[s] = PENDING + self._share_observers[s] = o = s.get_block(self.segnum) + o.subscribe(self._block_request_activity, share=s, shnum=shnum) + # TODO: build up a list of candidates, then walk through the + # list, sending requests to the most desireable servers, + # re-checking our block-hunger each time. For non-initial segment + # fetches, this would let us stick with faster servers. + return True + # nothing was sent: don't call us again until you have more shares to + # work with, or one of the existing shares has been declared OVERDUE + return False + + def _cancel_all_requests(self): + for o in self._share_observers.values(): + o.cancel() + self._share_observers = {} + + def _block_request_activity(self, share, shnum, state, block=None, f=None): + # called by Shares, in response to our s.send_request() calls. + if not self._running: + return + log.msg("SegmentFetcher(%s)._block_request_activity:" + " Share(sh%d-on-%s) -> %s" % + (self._node._si_prefix, shnum, share._peerid_s, state), + level=log.NOISY, umid="vilNWA") + # COMPLETE, CORRUPT, DEAD, BADSEGNUM are terminal. + if state in (COMPLETE, CORRUPT, DEAD, BADSEGNUM): + self._share_observers.pop(share, None) + if state is COMPLETE: + # 'block' is fully validated + self._shares[share] = COMPLETE + self._blocks[shnum] = block + elif state is OVERDUE: + self._shares[share] = OVERDUE + # OVERDUE is not terminal: it will eventually transition to + # COMPLETE, CORRUPT, or DEAD. + elif state is CORRUPT: + self._shares[share] = CORRUPT + elif state is DEAD: + del self._shares[share] + self._shnums[shnum].remove(share) + self._last_failure = f + elif state is BADSEGNUM: + self._shares[share] = BADSEGNUM # ??? + self._bad_segnum = True + eventually(self.loop) + + diff --git a/src/allmydata/immutable/downloader/finder.py b/src/allmydata/immutable/downloader/finder.py new file mode 100644 index 00000000..1a2a94da --- /dev/null +++ b/src/allmydata/immutable/downloader/finder.py @@ -0,0 +1,202 @@ + +import time +now = time.time +from foolscap.api import eventually +from allmydata.util import base32, log, idlib + +from share import Share, CommonShare + +def incidentally(res, f, *args, **kwargs): + """Add me to a Deferred chain like this: + d.addBoth(incidentally, func, arg) + and I'll behave as if you'd added the following function: + def _(res): + func(arg) + return res + This is useful if you want to execute an expression when the Deferred + fires, but don't care about its value. + """ + f(*args, **kwargs) + return res + +class RequestToken: + def __init__(self, peerid): + self.peerid = peerid + +class ShareFinder: + def __init__(self, storage_broker, verifycap, node, download_status, + logparent=None, max_outstanding_requests=10): + self.running = True # stopped by Share.stop, from Terminator + self.verifycap = verifycap + self._started = False + self._storage_broker = storage_broker + self.share_consumer = self.node = node + self.max_outstanding_requests = max_outstanding_requests + + self._hungry = False + + self._commonshares = {} # shnum to CommonShare instance + self.undelivered_shares = [] + self.pending_requests = set() + + self._storage_index = verifycap.storage_index + self._si_prefix = base32.b2a_l(self._storage_index[:8], 60) + self._node_logparent = logparent + self._download_status = download_status + self._lp = log.msg(format="ShareFinder[si=%(si)s] starting", + si=self._si_prefix, + level=log.NOISY, parent=logparent, umid="2xjj2A") + + def start_finding_servers(self): + # don't get servers until somebody uses us: creating the + # ImmutableFileNode should not cause work to happen yet. Test case is + # test_dirnode, which creates us with storage_broker=None + if not self._started: + si = self.verifycap.storage_index + s = self._storage_broker.get_servers_for_index(si) + self._servers = iter(s) + self._started = True + + def log(self, *args, **kwargs): + if "parent" not in kwargs: + kwargs["parent"] = self._lp + return log.msg(*args, **kwargs) + + def stop(self): + self.running = False + + # called by our parent CiphertextDownloader + def hungry(self): + self.log(format="ShareFinder[si=%(si)s] hungry", + si=self._si_prefix, level=log.NOISY, umid="NywYaQ") + self.start_finding_servers() + self._hungry = True + eventually(self.loop) + + # internal methods + def loop(self): + undelivered_s = ",".join(["sh%d@%s" % + (s._shnum, idlib.shortnodeid_b2a(s._peerid)) + for s in self.undelivered_shares]) + pending_s = ",".join([idlib.shortnodeid_b2a(rt.peerid) + for rt in self.pending_requests]) # sort? + self.log(format="ShareFinder loop: running=%(running)s" + " hungry=%(hungry)s, undelivered=%(undelivered)s," + " pending=%(pending)s", + running=self.running, hungry=self._hungry, + undelivered=undelivered_s, pending=pending_s, + level=log.NOISY, umid="kRtS4Q") + if not self.running: + return + if not self._hungry: + return + if self.undelivered_shares: + sh = self.undelivered_shares.pop(0) + # they will call hungry() again if they want more + self._hungry = False + self.log(format="delivering Share(shnum=%(shnum)d, server=%(peerid)s)", + shnum=sh._shnum, peerid=sh._peerid_s, + level=log.NOISY, umid="2n1qQw") + eventually(self.share_consumer.got_shares, [sh]) + return + + if len(self.pending_requests) >= self.max_outstanding_requests: + # cannot send more requests, must wait for some to retire + return + + server = None + try: + if self._servers: + server = self._servers.next() + except StopIteration: + self._servers = None + + if server: + self.send_request(server) + # we loop again to get parallel queries. The check above will + # prevent us from looping forever. + eventually(self.loop) + return + + if self.pending_requests: + # no server, but there are still requests in flight: maybe one of + # them will make progress + return + + self.log(format="ShareFinder.loop: no_more_shares, ever", + level=log.UNUSUAL, umid="XjQlzg") + # we've run out of servers (so we can't send any more requests), and + # we have nothing in flight. No further progress can be made. They + # are destined to remain hungry. + self.share_consumer.no_more_shares() + + def send_request(self, server): + peerid, rref = server + req = RequestToken(peerid) + self.pending_requests.add(req) + lp = self.log(format="sending DYHB to [%(peerid)s]", + peerid=idlib.shortnodeid_b2a(peerid), + level=log.NOISY, umid="Io7pyg") + d_ev = self._download_status.add_dyhb_sent(peerid, now()) + d = rref.callRemote("get_buckets", self._storage_index) + d.addBoth(incidentally, self.pending_requests.discard, req) + d.addCallbacks(self._got_response, self._got_error, + callbackArgs=(rref.version, peerid, req, d_ev, lp), + errbackArgs=(peerid, req, d_ev, lp)) + d.addErrback(log.err, format="error in send_request", + level=log.WEIRD, parent=lp, umid="rpdV0w") + d.addCallback(incidentally, eventually, self.loop) + + def _got_response(self, buckets, server_version, peerid, req, d_ev, lp): + shnums = sorted([shnum for shnum in buckets]) + d_ev.finished(shnums, now()) + if buckets: + shnums_s = ",".join([str(shnum) for shnum in shnums]) + self.log(format="got shnums [%(shnums)s] from [%(peerid)s]", + shnums=shnums_s, peerid=idlib.shortnodeid_b2a(peerid), + level=log.NOISY, parent=lp, umid="0fcEZw") + else: + self.log(format="no shares from [%(peerid)s]", + peerid=idlib.shortnodeid_b2a(peerid), + level=log.NOISY, parent=lp, umid="U7d4JA") + if self.node.num_segments is None: + best_numsegs = self.node.guessed_num_segments + else: + best_numsegs = self.node.num_segments + for shnum, bucket in buckets.iteritems(): + self._create_share(best_numsegs, shnum, bucket, server_version, + peerid) + + def _create_share(self, best_numsegs, shnum, bucket, server_version, + peerid): + if shnum in self._commonshares: + cs = self._commonshares[shnum] + else: + cs = CommonShare(best_numsegs, self._si_prefix, shnum, + self._node_logparent) + # Share._get_satisfaction is responsible for updating + # CommonShare.set_numsegs after we know the UEB. Alternatives: + # 1: d = self.node.get_num_segments() + # d.addCallback(cs.got_numsegs) + # the problem is that the OneShotObserverList I was using + # inserts an eventual-send between _get_satisfaction's + # _satisfy_UEB and _satisfy_block_hash_tree, and the + # CommonShare didn't get the num_segs message before + # being asked to set block hash values. To resolve this + # would require an immediate ObserverList instead of + # an eventual-send -based one + # 2: break _get_satisfaction into Deferred-attached pieces. + # Yuck. + self._commonshares[shnum] = cs + s = Share(bucket, server_version, self.verifycap, cs, self.node, + self._download_status, peerid, shnum, + self._node_logparent) + self.undelivered_shares.append(s) + + def _got_error(self, f, peerid, req, d_ev, lp): + d_ev.finished("error", now()) + self.log(format="got error from [%(peerid)s]", + peerid=idlib.shortnodeid_b2a(peerid), failure=f, + level=log.UNUSUAL, parent=lp, umid="zUKdCw") + + diff --git a/src/allmydata/immutable/downloader/node.py b/src/allmydata/immutable/downloader/node.py new file mode 100644 index 00000000..2991c9ee --- /dev/null +++ b/src/allmydata/immutable/downloader/node.py @@ -0,0 +1,471 @@ + +import time +now = time.time +from twisted.python.failure import Failure +from twisted.internet import defer +from foolscap.api import eventually +from allmydata import uri +from allmydata.codec import CRSDecoder +from allmydata.util import base32, log, hashutil, mathutil, observer +from allmydata.interfaces import DEFAULT_MAX_SEGMENT_SIZE +from allmydata.hashtree import IncompleteHashTree, BadHashError, \ + NotEnoughHashesError + +# local imports +from finder import ShareFinder +from fetcher import SegmentFetcher +from segmentation import Segmentation +from common import BadCiphertextHashError + +class Cancel: + def __init__(self, f): + self._f = f + self.cancelled = False + def cancel(self): + if not self.cancelled: + self.cancelled = True + self._f(self) + +class DownloadNode: + """Internal class which manages downloads and holds state. External + callers use CiphertextFileNode instead.""" + + # Share._node points to me + def __init__(self, verifycap, storage_broker, secret_holder, + terminator, history, download_status): + assert isinstance(verifycap, uri.CHKFileVerifierURI) + self._verifycap = verifycap + self._storage_broker = storage_broker + self._si_prefix = base32.b2a_l(verifycap.storage_index[:8], 60) + self.running = True + if terminator: + terminator.register(self) # calls self.stop() at stopService() + # the rules are: + # 1: Only send network requests if you're active (self.running is True) + # 2: Use TimerService, not reactor.callLater + # 3: You can do eventual-sends any time. + # These rules should mean that once + # stopService()+flushEventualQueue() fires, everything will be done. + self._secret_holder = secret_holder + self._history = history + self._download_status = download_status + + k, N = self._verifycap.needed_shares, self._verifycap.total_shares + self.share_hash_tree = IncompleteHashTree(N) + + # we guess the segment size, so Segmentation can pull non-initial + # segments in a single roundtrip. This populates + # .guessed_segment_size, .guessed_num_segments, and + # .ciphertext_hash_tree (with a dummy, to let us guess which hashes + # we'll need) + self._build_guessed_tables(DEFAULT_MAX_SEGMENT_SIZE) + + # filled in when we parse a valid UEB + self.have_UEB = False + self.segment_size = None + self.tail_segment_size = None + self.tail_segment_padded = None + self.num_segments = None + self.block_size = None + self.tail_block_size = None + + # things to track callers that want data + + # _segment_requests can have duplicates + self._segment_requests = [] # (segnum, d, cancel_handle) + self._active_segment = None # a SegmentFetcher, with .segnum + + self._segsize_observers = observer.OneShotObserverList() + + # we create one top-level logparent for this _Node, and another one + # for each read() call. Segmentation and get_segment() messages are + # associated with the read() call, everything else is tied to the + # _Node's log entry. + lp = log.msg(format="Immutable _Node(%(si)s) created: size=%(size)d," + " guessed_segsize=%(guessed_segsize)d," + " guessed_numsegs=%(guessed_numsegs)d", + si=self._si_prefix, size=verifycap.size, + guessed_segsize=self.guessed_segment_size, + guessed_numsegs=self.guessed_num_segments, + level=log.OPERATIONAL, umid="uJ0zAQ") + self._lp = lp + + self._sharefinder = ShareFinder(storage_broker, verifycap, self, + self._download_status, lp) + self._shares = set() + + def _build_guessed_tables(self, max_segment_size): + size = min(self._verifycap.size, max_segment_size) + s = mathutil.next_multiple(size, self._verifycap.needed_shares) + self.guessed_segment_size = s + r = self._calculate_sizes(self.guessed_segment_size) + self.guessed_num_segments = r["num_segments"] + # as with CommonShare, our ciphertext_hash_tree is a stub until we + # get the real num_segments + self.ciphertext_hash_tree = IncompleteHashTree(self.guessed_num_segments) + + def __repr__(self): + return "Imm_Node(%s)" % (self._si_prefix,) + + def stop(self): + # called by the Terminator at shutdown, mostly for tests + if self._active_segment: + self._active_segment.stop() + self._active_segment = None + self._sharefinder.stop() + + # things called by outside callers, via CiphertextFileNode. get_segment() + # may also be called by Segmentation. + + def read(self, consumer, offset=0, size=None, read_ev=None): + """I am the main entry point, from which FileNode.read() can get + data. I feed the consumer with the desired range of ciphertext. I + return a Deferred that fires (with the consumer) when the read is + finished. + + Note that there is no notion of a 'file pointer': each call to read() + uses an independent offset= value.""" + # for concurrent operations: each gets its own Segmentation manager + if size is None: + size = self._verifycap.size + # clip size so offset+size does not go past EOF + size = min(size, self._verifycap.size-offset) + if read_ev is None: + read_ev = self._download_status.add_read_event(offset, size, now()) + + lp = log.msg(format="imm Node(%(si)s).read(%(offset)d, %(size)d)", + si=base32.b2a(self._verifycap.storage_index)[:8], + offset=offset, size=size, + level=log.OPERATIONAL, parent=self._lp, umid="l3j3Ww") + if self._history: + sp = self._history.stats_provider + sp.count("downloader.files_downloaded", 1) # really read() calls + sp.count("downloader.bytes_downloaded", size) + s = Segmentation(self, offset, size, consumer, read_ev, lp) + # this raises an interesting question: what segments to fetch? if + # offset=0, always fetch the first segment, and then allow + # Segmentation to be responsible for pulling the subsequent ones if + # the first wasn't large enough. If offset>0, we're going to need an + # extra roundtrip to get the UEB (and therefore the segment size) + # before we can figure out which segment to get. TODO: allow the + # offset-table-guessing code (which starts by guessing the segsize) + # to assist the offset>0 process. + d = s.start() + def _done(res): + read_ev.finished(now()) + return res + d.addBoth(_done) + return d + + def get_segment(self, segnum, logparent=None): + """Begin downloading a segment. I return a tuple (d, c): 'd' is a + Deferred that fires with (offset,data) when the desired segment is + available, and c is an object on which c.cancel() can be called to + disavow interest in the segment (after which 'd' will never fire). + + You probably need to know the segment size before calling this, + unless you want the first few bytes of the file. If you ask for a + segment number which turns out to be too large, the Deferred will + errback with BadSegmentNumberError. + + The Deferred fires with the offset of the first byte of the data + segment, so that you can call get_segment() before knowing the + segment size, and still know which data you received. + + The Deferred can also errback with other fatal problems, such as + NotEnoughSharesError, NoSharesError, or BadCiphertextHashError. + """ + log.msg(format="imm Node(%(si)s).get_segment(%(segnum)d)", + si=base32.b2a(self._verifycap.storage_index)[:8], + segnum=segnum, + level=log.OPERATIONAL, parent=logparent, umid="UKFjDQ") + self._download_status.add_segment_request(segnum, now()) + d = defer.Deferred() + c = Cancel(self._cancel_request) + self._segment_requests.append( (segnum, d, c) ) + self._start_new_segment() + return (d, c) + + def get_segsize(self): + """Return a Deferred that fires when we know the real segment size.""" + if self.segment_size: + return defer.succeed(self.segment_size) + # TODO: this downloads (and discards) the first segment of the file. + # We could make this more efficient by writing + # fetcher.SegmentSizeFetcher, with the job of finding a single valid + # share and extracting the UEB. We'd add Share.get_UEB() to request + # just the UEB. + (d,c) = self.get_segment(0) + # this ensures that an error during get_segment() will errback the + # caller, so Repair won't wait forever on completely missing files + d.addCallback(lambda ign: self._segsize_observers.when_fired()) + return d + + # things called by the Segmentation object used to transform + # arbitrary-sized read() calls into quantized segment fetches + + def _start_new_segment(self): + if self._active_segment is None and self._segment_requests: + segnum = self._segment_requests[0][0] + k = self._verifycap.needed_shares + log.msg(format="%(node)s._start_new_segment: segnum=%(segnum)d", + node=repr(self), segnum=segnum, + level=log.NOISY, umid="wAlnHQ") + self._active_segment = fetcher = SegmentFetcher(self, segnum, k) + active_shares = [s for s in self._shares if s.is_alive()] + fetcher.add_shares(active_shares) # this triggers the loop + + + # called by our child ShareFinder + def got_shares(self, shares): + self._shares.update(shares) + if self._active_segment: + self._active_segment.add_shares(shares) + def no_more_shares(self): + self._no_more_shares = True + if self._active_segment: + self._active_segment.no_more_shares() + + # things called by our Share instances + + def validate_and_store_UEB(self, UEB_s): + log.msg("validate_and_store_UEB", + level=log.OPERATIONAL, parent=self._lp, umid="7sTrPw") + h = hashutil.uri_extension_hash(UEB_s) + if h != self._verifycap.uri_extension_hash: + raise BadHashError + UEB_dict = uri.unpack_extension(UEB_s) + self._parse_and_store_UEB(UEB_dict) # sets self._stuff + # TODO: a malformed (but authentic) UEB could throw an assertion in + # _parse_and_store_UEB, and we should abandon the download. + self.have_UEB = True + + def _parse_and_store_UEB(self, d): + # Note: the UEB contains needed_shares and total_shares. These are + # redundant and inferior (the filecap contains the authoritative + # values). However, because it is possible to encode the same file in + # multiple ways, and the encoders might choose (poorly) to use the + # same key for both (therefore getting the same SI), we might + # encounter shares for both types. The UEB hashes will be different, + # however, and we'll disregard the "other" encoding's shares as + # corrupted. + + # therefore, we ignore d['total_shares'] and d['needed_shares']. + + log.msg(format="UEB=%(ueb)s, vcap=%(vcap)s", + ueb=repr(d), vcap=self._verifycap.to_string(), + level=log.NOISY, parent=self._lp, umid="cVqZnA") + + k, N = self._verifycap.needed_shares, self._verifycap.total_shares + + self.segment_size = d['segment_size'] + self._segsize_observers.fire(self.segment_size) + + r = self._calculate_sizes(self.segment_size) + self.tail_segment_size = r["tail_segment_size"] + self.tail_segment_padded = r["tail_segment_padded"] + self.num_segments = r["num_segments"] + self.block_size = r["block_size"] + self.tail_block_size = r["tail_block_size"] + log.msg("actual sizes: %s" % (r,), + level=log.NOISY, parent=self._lp, umid="PY6P5Q") + if (self.segment_size == self.guessed_segment_size + and self.num_segments == self.guessed_num_segments): + log.msg("my guess was right!", + level=log.NOISY, parent=self._lp, umid="x340Ow") + else: + log.msg("my guess was wrong! Extra round trips for me.", + level=log.NOISY, parent=self._lp, umid="tb7RJw") + + # zfec.Decode() instantiation is fast, but still, let's use the same + # codec instance for all but the last segment. 3-of-10 takes 15us on + # my laptop, 25-of-100 is 900us, 3-of-255 is 97us, 25-of-255 is + # 2.5ms, worst-case 254-of-255 is 9.3ms + self._codec = CRSDecoder() + self._codec.set_params(self.segment_size, k, N) + + + # Ciphertext hash tree root is mandatory, so that there is at most + # one ciphertext that matches this read-cap or verify-cap. The + # integrity check on the shares is not sufficient to prevent the + # original encoder from creating some shares of file A and other + # shares of file B. self.ciphertext_hash_tree was a guess before: + # this is where we create it for real. + self.ciphertext_hash_tree = IncompleteHashTree(self.num_segments) + self.ciphertext_hash_tree.set_hashes({0: d['crypttext_root_hash']}) + + self.share_hash_tree.set_hashes({0: d['share_root_hash']}) + + # Our job is a fast download, not verification, so we ignore any + # redundant fields. The Verifier uses a different code path which + # does not ignore them. + + def _calculate_sizes(self, segment_size): + # segments of ciphertext + size = self._verifycap.size + k = self._verifycap.needed_shares + + # this assert matches the one in encode.py:127 inside + # Encoded._got_all_encoding_parameters, where the UEB is constructed + assert segment_size % k == 0 + + # the last segment is usually short. We don't store a whole segsize, + # but we do pad the segment up to a multiple of k, because the + # encoder requires that. + tail_segment_size = size % segment_size + if tail_segment_size == 0: + tail_segment_size = segment_size + padded = mathutil.next_multiple(tail_segment_size, k) + tail_segment_padded = padded + + num_segments = mathutil.div_ceil(size, segment_size) + + # each segment is turned into N blocks. All but the last are of size + # block_size, and the last is of size tail_block_size + block_size = segment_size / k + tail_block_size = tail_segment_padded / k + + return { "tail_segment_size": tail_segment_size, + "tail_segment_padded": tail_segment_padded, + "num_segments": num_segments, + "block_size": block_size, + "tail_block_size": tail_block_size, + } + + + def process_share_hashes(self, share_hashes): + for hashnum in share_hashes: + if hashnum >= len(self.share_hash_tree): + # "BadHashError" is normally for e.g. a corrupt block. We + # sort of abuse it here to mean a badly numbered hash (which + # indicates corruption in the number bytes, rather than in + # the data bytes). + raise BadHashError("hashnum %d doesn't fit in hashtree(%d)" + % (hashnum, len(self.share_hash_tree))) + self.share_hash_tree.set_hashes(share_hashes) + + def get_needed_ciphertext_hashes(self, segnum): + cht = self.ciphertext_hash_tree + return cht.needed_hashes(segnum, include_leaf=True) + def process_ciphertext_hashes(self, hashes): + assert self.num_segments is not None + # this may raise BadHashError or NotEnoughHashesError + self.ciphertext_hash_tree.set_hashes(hashes) + + + # called by our child SegmentFetcher + + def want_more_shares(self): + self._sharefinder.hungry() + + def fetch_failed(self, sf, f): + assert sf is self._active_segment + self._active_segment = None + # deliver error upwards + for (d,c) in self._extract_requests(sf.segnum): + eventually(self._deliver, d, c, f) + + def process_blocks(self, segnum, blocks): + d = defer.maybeDeferred(self._decode_blocks, segnum, blocks) + d.addCallback(self._check_ciphertext_hash, segnum) + def _deliver(result): + ds = self._download_status + if isinstance(result, Failure): + ds.add_segment_error(segnum, now()) + else: + (offset, segment, decodetime) = result + ds.add_segment_delivery(segnum, now(), + offset, len(segment), decodetime) + log.msg(format="delivering segment(%(segnum)d)", + segnum=segnum, + level=log.OPERATIONAL, parent=self._lp, + umid="j60Ojg") + for (d,c) in self._extract_requests(segnum): + eventually(self._deliver, d, c, result) + self._active_segment = None + self._start_new_segment() + d.addBoth(_deliver) + d.addErrback(lambda f: + log.err("unhandled error during process_blocks", + failure=f, level=log.WEIRD, + parent=self._lp, umid="MkEsCg")) + + def _decode_blocks(self, segnum, blocks): + tail = (segnum == self.num_segments-1) + codec = self._codec + block_size = self.block_size + decoded_size = self.segment_size + if tail: + # account for the padding in the last segment + codec = CRSDecoder() + k, N = self._verifycap.needed_shares, self._verifycap.total_shares + codec.set_params(self.tail_segment_padded, k, N) + block_size = self.tail_block_size + decoded_size = self.tail_segment_padded + + shares = [] + shareids = [] + for (shareid, share) in blocks.iteritems(): + assert len(share) == block_size + shareids.append(shareid) + shares.append(share) + del blocks + + start = now() + d = codec.decode(shares, shareids) # segment + del shares + def _process(buffers): + decodetime = now() - start + segment = "".join(buffers) + assert len(segment) == decoded_size + del buffers + if tail: + segment = segment[:self.tail_segment_size] + return (segment, decodetime) + d.addCallback(_process) + return d + + def _check_ciphertext_hash(self, (segment, decodetime), segnum): + assert self._active_segment.segnum == segnum + assert self.segment_size is not None + offset = segnum * self.segment_size + + h = hashutil.crypttext_segment_hash(segment) + try: + self.ciphertext_hash_tree.set_hashes(leaves={segnum: h}) + return (offset, segment, decodetime) + except (BadHashError, NotEnoughHashesError): + format = ("hash failure in ciphertext_hash_tree:" + " segnum=%(segnum)d, SI=%(si)s") + log.msg(format=format, segnum=segnum, si=self._si_prefix, + failure=Failure(), + level=log.WEIRD, parent=self._lp, umid="MTwNnw") + # this is especially weird, because we made it past the share + # hash tree. It implies that we're using the wrong encoding, or + # that the uploader deliberately constructed a bad UEB. + msg = format % {"segnum": segnum, "si": self._si_prefix} + raise BadCiphertextHashError(msg) + + def _deliver(self, d, c, result): + # this method exists to handle cancel() that occurs between + # _got_segment and _deliver + if not c.cancelled: + d.callback(result) # might actually be an errback + + def _extract_requests(self, segnum): + """Remove matching requests and return their (d,c) tuples so that the + caller can retire them.""" + retire = [(d,c) for (segnum0, d, c) in self._segment_requests + if segnum0 == segnum] + self._segment_requests = [t for t in self._segment_requests + if t[0] != segnum] + return retire + + def _cancel_request(self, c): + self._segment_requests = [t for t in self._segment_requests + if t[2] != c] + segnums = [segnum for (segnum,d,c) in self._segment_requests] + if self._active_segment.segnum not in segnums: + self._active_segment.stop() + self._active_segment = None + self._start_new_segment() diff --git a/src/allmydata/immutable/downloader/segmentation.py b/src/allmydata/immutable/downloader/segmentation.py new file mode 100644 index 00000000..4890195c --- /dev/null +++ b/src/allmydata/immutable/downloader/segmentation.py @@ -0,0 +1,160 @@ + +import time +now = time.time +from zope.interface import implements +from twisted.internet import defer +from twisted.internet.interfaces import IPushProducer +from foolscap.api import eventually +from allmydata.util import log +from allmydata.util.spans import overlap + +from common import BadSegmentNumberError, WrongSegmentError, DownloadStopped + +class Segmentation: + """I am responsible for a single offset+size read of the file. I handle + segmentation: I figure out which segments are necessary, request them + (from my CiphertextDownloader) in order, and trim the segments down to + match the offset+size span. I use the Producer/Consumer interface to only + request one segment at a time. + """ + implements(IPushProducer) + def __init__(self, node, offset, size, consumer, read_ev, logparent=None): + self._node = node + self._hungry = True + self._active_segnum = None + self._cancel_segment_request = None + # these are updated as we deliver data. At any given time, we still + # want to download file[offset:offset+size] + self._offset = offset + self._size = size + assert offset+size <= node._verifycap.size + self._consumer = consumer + self._read_ev = read_ev + self._start_pause = None + self._lp = logparent + + def start(self): + self._alive = True + self._deferred = defer.Deferred() + self._consumer.registerProducer(self, True) + self._maybe_fetch_next() + return self._deferred + + def _maybe_fetch_next(self): + if not self._alive or not self._hungry: + return + if self._active_segnum is not None: + return + self._fetch_next() + + def _fetch_next(self): + if self._size == 0: + # done! + self._alive = False + self._hungry = False + self._consumer.unregisterProducer() + self._deferred.callback(self._consumer) + return + n = self._node + have_actual_segment_size = n.segment_size is not None + guess_s = "" + if not have_actual_segment_size: + guess_s = "probably " + segment_size = n.segment_size or n.guessed_segment_size + if self._offset == 0: + # great! we want segment0 for sure + wanted_segnum = 0 + else: + # this might be a guess + wanted_segnum = self._offset // segment_size + log.msg(format="_fetch_next(offset=%(offset)d) %(guess)swants segnum=%(segnum)d", + offset=self._offset, guess=guess_s, segnum=wanted_segnum, + level=log.NOISY, parent=self._lp, umid="5WfN0w") + self._active_segnum = wanted_segnum + d,c = n.get_segment(wanted_segnum, self._lp) + self._cancel_segment_request = c + d.addBoth(self._request_retired) + d.addCallback(self._got_segment, wanted_segnum) + if not have_actual_segment_size: + # we can retry once + d.addErrback(self._retry_bad_segment) + d.addErrback(self._error) + + def _request_retired(self, res): + self._active_segnum = None + self._cancel_segment_request = None + return res + + def _got_segment(self, (segment_start,segment,decodetime), wanted_segnum): + self._cancel_segment_request = None + # we got file[segment_start:segment_start+len(segment)] + # we want file[self._offset:self._offset+self._size] + log.msg(format="Segmentation got data:" + " want [%(wantstart)d-%(wantend)d)," + " given [%(segstart)d-%(segend)d), for segnum=%(segnum)d", + wantstart=self._offset, wantend=self._offset+self._size, + segstart=segment_start, segend=segment_start+len(segment), + segnum=wanted_segnum, + level=log.OPERATIONAL, parent=self._lp, umid="32dHcg") + + o = overlap(segment_start, len(segment), self._offset, self._size) + # the overlap is file[o[0]:o[0]+o[1]] + if not o or o[0] != self._offset: + # we didn't get the first byte, so we can't use this segment + log.msg("Segmentation handed wrong data:" + " want [%d-%d), given [%d-%d), for segnum=%d," + " for si=%s" + % (self._offset, self._offset+self._size, + segment_start, segment_start+len(segment), + wanted_segnum, self._node._si_prefix), + level=log.UNUSUAL, parent=self._lp, umid="STlIiA") + # we may retry if the segnum we asked was based on a guess + raise WrongSegmentError("I was given the wrong data.") + offset_in_segment = self._offset - segment_start + desired_data = segment[offset_in_segment:offset_in_segment+o[1]] + + self._offset += len(desired_data) + self._size -= len(desired_data) + self._consumer.write(desired_data) + # the consumer might call our .pauseProducing() inside that write() + # call, setting self._hungry=False + self._read_ev.update(len(desired_data), 0, 0) + self._maybe_fetch_next() + + def _retry_bad_segment(self, f): + f.trap(WrongSegmentError, BadSegmentNumberError) + # we guessed the segnum wrong: either one that doesn't overlap with + # the start of our desired region, or one that's beyond the end of + # the world. Now that we have the right information, we're allowed to + # retry once. + assert self._node.segment_size is not None + return self._maybe_fetch_next() + + def _error(self, f): + log.msg("Error in Segmentation", failure=f, + level=log.WEIRD, parent=self._lp, umid="EYlXBg") + self._alive = False + self._hungry = False + self._consumer.unregisterProducer() + self._deferred.errback(f) + + def stopProducing(self): + self._hungry = False + self._alive = False + # cancel any outstanding segment request + if self._cancel_segment_request: + self._cancel_segment_request.cancel() + self._cancel_segment_request = None + e = DownloadStopped("our Consumer called stopProducing()") + self._deferred.errback(e) + + def pauseProducing(self): + self._hungry = False + self._start_pause = now() + def resumeProducing(self): + self._hungry = True + eventually(self._maybe_fetch_next) + if self._start_pause is not None: + paused = now() - self._start_pause + self._read_ev.update(0, 0, paused) + self._start_pause = None diff --git a/src/allmydata/immutable/downloader/share.py b/src/allmydata/immutable/downloader/share.py new file mode 100644 index 00000000..e3c90176 --- /dev/null +++ b/src/allmydata/immutable/downloader/share.py @@ -0,0 +1,848 @@ + +import struct +import time +now = time.time + +from twisted.python.failure import Failure +from foolscap.api import eventually +from allmydata.util import base32, log, hashutil, mathutil +from allmydata.util.spans import Spans, DataSpans +from allmydata.interfaces import HASH_SIZE +from allmydata.hashtree import IncompleteHashTree, BadHashError, \ + NotEnoughHashesError + +from allmydata.immutable.layout import make_write_bucket_proxy +from allmydata.util.observer import EventStreamObserver +from common import COMPLETE, CORRUPT, DEAD, BADSEGNUM + + +class LayoutInvalid(Exception): + pass +class DataUnavailable(Exception): + pass + +class Share: + """I represent a single instance of a single share (e.g. I reference the + shnum2 for share SI=abcde on server xy12t, not the one on server ab45q). + I am associated with a CommonShare that remembers data that is held in + common among e.g. SI=abcde/shnum2 across all servers. I am also + associated with a CiphertextFileNode for e.g. SI=abcde (all shares, all + servers). + """ + # this is a specific implementation of IShare for tahoe's native storage + # servers. A different backend would use a different class. + + def __init__(self, rref, server_version, verifycap, commonshare, node, + download_status, peerid, shnum, logparent): + self._rref = rref + self._server_version = server_version + self._node = node # holds share_hash_tree and UEB + self.actual_segment_size = node.segment_size # might still be None + # XXX change node.guessed_segment_size to + # node.best_guess_segment_size(), which should give us the real ones + # if known, else its guess. + self._guess_offsets(verifycap, node.guessed_segment_size) + self.actual_offsets = None + self._UEB_length = None + self._commonshare = commonshare # holds block_hash_tree + self._download_status = download_status + self._peerid = peerid + self._peerid_s = base32.b2a(peerid)[:5] + self._storage_index = verifycap.storage_index + self._si_prefix = base32.b2a(verifycap.storage_index)[:8] + self._shnum = shnum + # self._alive becomes False upon fatal corruption or server error + self._alive = True + self._lp = log.msg(format="%(share)s created", share=repr(self), + level=log.NOISY, parent=logparent, umid="P7hv2w") + + self._pending = Spans() # request sent but no response received yet + self._received = DataSpans() # ACK response received, with data + self._unavailable = Spans() # NAK response received, no data + + # any given byte of the share can be in one of four states: + # in: _wanted, _requested, _received + # FALSE FALSE FALSE : don't care about it at all + # TRUE FALSE FALSE : want it, haven't yet asked for it + # TRUE TRUE FALSE : request is in-flight + # or didn't get it + # FALSE TRUE TRUE : got it, haven't used it yet + # FALSE TRUE FALSE : got it and used it + # FALSE FALSE FALSE : block consumed, ready to ask again + # + # when we request data and get a NAK, we leave it in _requested + # to remind ourself to not ask for it again. We don't explicitly + # remove it from anything (maybe this should change). + # + # We retain the hashtrees in the Node, so we leave those spans in + # _requested (and never ask for them again, as long as the Node is + # alive). But we don't retain data blocks (too big), so when we + # consume a data block, we remove it from _requested, so a later + # download can re-fetch it. + + self._requested_blocks = [] # (segnum, set(observer2..)) + ver = server_version["http://allmydata.org/tahoe/protocols/storage/v1"] + self._overrun_ok = ver["tolerates-immutable-read-overrun"] + # If _overrun_ok and we guess the offsets correctly, we can get + # everything in one RTT. If _overrun_ok and we guess wrong, we might + # need two RTT (but we could get lucky and do it in one). If overrun + # is *not* ok (tahoe-1.3.0 or earlier), we need four RTT: 1=version, + # 2=offset table, 3=UEB_length and everything else (hashes, block), + # 4=UEB. + + self.had_corruption = False # for unit tests + + def __repr__(self): + return "Share(sh%d-on-%s)" % (self._shnum, self._peerid_s) + + def is_alive(self): + # XXX: reconsider. If the share sees a single error, should it remain + # dead for all time? Or should the next segment try again? This DEAD + # state is stored elsewhere too (SegmentFetcher per-share states?) + # and needs to be consistent. We clear _alive in self._fail(), which + # is called upon a network error, or layout failure, or hash failure + # in the UEB or a hash tree. We do not _fail() for a hash failure in + # a block, but of course we still tell our callers about + # state=CORRUPT so they'll find a different share. + return self._alive + + def _guess_offsets(self, verifycap, guessed_segment_size): + self.guessed_segment_size = guessed_segment_size + size = verifycap.size + k = verifycap.needed_shares + N = verifycap.total_shares + r = self._node._calculate_sizes(guessed_segment_size) + # num_segments, block_size/tail_block_size + # guessed_segment_size/tail_segment_size/tail_segment_padded + share_size = mathutil.div_ceil(size, k) + # share_size is the amount of block data that will be put into each + # share, summed over all segments. It does not include hashes, the + # UEB, or other overhead. + + # use the upload-side code to get this as accurate as possible + ht = IncompleteHashTree(N) + num_share_hashes = len(ht.needed_hashes(0, include_leaf=True)) + wbp = make_write_bucket_proxy(None, share_size, r["block_size"], + r["num_segments"], num_share_hashes, 0, + None) + self._fieldsize = wbp.fieldsize + self._fieldstruct = wbp.fieldstruct + self.guessed_offsets = wbp._offsets + + # called by our client, the SegmentFetcher + def get_block(self, segnum): + """Add a block number to the list of requests. This will eventually + result in a fetch of the data necessary to validate the block, then + the block itself. The fetch order is generally + first-come-first-served, but requests may be answered out-of-order if + data becomes available sooner. + + I return an EventStreamObserver, which has two uses. The first is to + call o.subscribe(), which gives me a place to send state changes and + eventually the data block. The second is o.cancel(), which removes + the request (if it is still active). + + I will distribute the following events through my EventStreamObserver: + - state=OVERDUE: ?? I believe I should have had an answer by now. + You may want to ask another share instead. + - state=BADSEGNUM: the segnum you asked for is too large. I must + fetch a valid UEB before I can determine this, + so the notification is asynchronous + - state=COMPLETE, block=data: here is a valid block + - state=CORRUPT: this share contains corrupted data + - state=DEAD, f=Failure: the server reported an error, this share + is unusable + """ + log.msg("%s.get_block(%d)" % (repr(self), segnum), + level=log.NOISY, parent=self._lp, umid="RTo9MQ") + assert segnum >= 0 + o = EventStreamObserver() + o.set_canceler(self, "_cancel_block_request") + for i,(segnum0,observers) in enumerate(self._requested_blocks): + if segnum0 == segnum: + observers.add(o) + break + else: + self._requested_blocks.append( (segnum, set([o])) ) + eventually(self.loop) + return o + + def _cancel_block_request(self, o): + new_requests = [] + for e in self._requested_blocks: + (segnum0, observers) = e + observers.discard(o) + if observers: + new_requests.append(e) + self._requested_blocks = new_requests + + # internal methods + def _active_segnum_and_observers(self): + if self._requested_blocks: + # we only retrieve information for one segment at a time, to + # minimize alacrity (first come, first served) + return self._requested_blocks[0] + return None, [] + + def loop(self): + try: + # if any exceptions occur here, kill the download + log.msg("%s.loop, reqs=[%s], pending=%s, received=%s," + " unavailable=%s" % + (repr(self), + ",".join([str(req[0]) for req in self._requested_blocks]), + self._pending.dump(), self._received.dump(), + self._unavailable.dump() ), + level=log.NOISY, parent=self._lp, umid="BaL1zw") + self._do_loop() + # all exception cases call self._fail(), which clears self._alive + except (BadHashError, NotEnoughHashesError, LayoutInvalid), e: + # Abandon this share. We do this if we see corruption in the + # offset table, the UEB, or a hash tree. We don't abandon the + # whole share if we see corruption in a data block (we abandon + # just the one block, and still try to get data from other blocks + # on the same server). In theory, we could get good data from a + # share with a corrupt UEB (by first getting the UEB from some + # other share), or corrupt hash trees, but the logic to decide + # when this is safe is non-trivial. So for now, give up at the + # first sign of corruption. + # + # _satisfy_*() code which detects corruption should first call + # self._signal_corruption(), and then raise the exception. + log.msg(format="corruption detected in %(share)s", + share=repr(self), + level=log.UNUSUAL, parent=self._lp, umid="gWspVw") + self._fail(Failure(e), log.UNUSUAL) + except DataUnavailable, e: + # Abandon this share. + log.msg(format="need data that will never be available" + " from %s: pending=%s, received=%s, unavailable=%s" % + (repr(self), + self._pending.dump(), self._received.dump(), + self._unavailable.dump() ), + level=log.UNUSUAL, parent=self._lp, umid="F7yJnQ") + self._fail(Failure(e), log.UNUSUAL) + except BaseException: + self._fail(Failure()) + raise + log.msg("%s.loop done, reqs=[%s], pending=%s, received=%s," + " unavailable=%s" % + (repr(self), + ",".join([str(req[0]) for req in self._requested_blocks]), + self._pending.dump(), self._received.dump(), + self._unavailable.dump() ), + level=log.NOISY, parent=self._lp, umid="9lRaRA") + + def _do_loop(self): + # we are (eventually) called after all state transitions: + # new segments added to self._requested_blocks + # new data received from servers (responses to our read() calls) + # impatience timer fires (server appears slow) + if not self._alive: + return + + # First, consume all of the information that we currently have, for + # all the segments people currently want. + while self._get_satisfaction(): + pass + + # When we get no satisfaction (from the data we've received so far), + # we determine what data we desire (to satisfy more requests). The + # number of segments is finite, so I can't get no satisfaction + # forever. + wanted, needed = self._desire() + + # Finally, send out requests for whatever we need (desire minus + # have). You can't always get what you want, but if you try + # sometimes, you just might find, you get what you need. + self._send_requests(wanted + needed) + + # and sometimes you can't even get what you need + disappointment = needed & self._unavailable + if len(disappointment): + self.had_corruption = True + raise DataUnavailable("need %s but will never get it" % + disappointment.dump()) + + def _get_satisfaction(self): + # return True if we retired a data block, and should therefore be + # called again. Return False if we don't retire a data block (even if + # we do retire some other data, like hash chains). + + if self.actual_offsets is None: + if not self._satisfy_offsets(): + # can't even look at anything without the offset table + return False + + if not self._node.have_UEB: + if not self._satisfy_UEB(): + # can't check any hashes without the UEB + return False + self.actual_segment_size = self._node.segment_size # might be updated + assert self.actual_segment_size is not None + + # knowing the UEB means knowing num_segments. Despite the redundancy, + # this is the best place to set this. CommonShare.set_numsegs will + # ignore duplicate calls. + assert self._node.num_segments is not None + cs = self._commonshare + cs.set_numsegs(self._node.num_segments) + + segnum, observers = self._active_segnum_and_observers() + # if segnum is None, we don't really need to do anything (we have no + # outstanding readers right now), but we'll fill in the bits that + # aren't tied to any particular segment. + + if segnum is not None and segnum >= self._node.num_segments: + for o in observers: + o.notify(state=BADSEGNUM) + self._requested_blocks.pop(0) + return True + + if self._node.share_hash_tree.needed_hashes(self._shnum): + if not self._satisfy_share_hash_tree(): + # can't check block_hash_tree without a root + return False + + if cs.need_block_hash_root(): + block_hash_root = self._node.share_hash_tree.get_leaf(self._shnum) + cs.set_block_hash_root(block_hash_root) + + if segnum is None: + return False # we don't want any particular segment right now + + # block_hash_tree + needed_hashes = self._commonshare.get_needed_block_hashes(segnum) + if needed_hashes: + if not self._satisfy_block_hash_tree(needed_hashes): + # can't check block without block_hash_tree + return False + + # ciphertext_hash_tree + needed_hashes = self._node.get_needed_ciphertext_hashes(segnum) + if needed_hashes: + if not self._satisfy_ciphertext_hash_tree(needed_hashes): + # can't check decoded blocks without ciphertext_hash_tree + return False + + # data blocks + return self._satisfy_data_block(segnum, observers) + + def _satisfy_offsets(self): + version_s = self._received.get(0, 4) + if version_s is None: + return False + (version,) = struct.unpack(">L", version_s) + if version == 1: + table_start = 0x0c + self._fieldsize = 0x4 + self._fieldstruct = "L" + elif version == 2: + table_start = 0x14 + self._fieldsize = 0x8 + self._fieldstruct = "Q" + else: + self.had_corruption = True + raise LayoutInvalid("unknown version %d (I understand 1 and 2)" + % version) + offset_table_size = 6 * self._fieldsize + table_s = self._received.pop(table_start, offset_table_size) + if table_s is None: + return False + fields = struct.unpack(">"+6*self._fieldstruct, table_s) + offsets = {} + for i,field in enumerate(['data', + 'plaintext_hash_tree', # UNUSED + 'crypttext_hash_tree', + 'block_hashes', + 'share_hashes', + 'uri_extension', + ] ): + offsets[field] = fields[i] + self.actual_offsets = offsets + log.msg("actual offsets: data=%d, plaintext_hash_tree=%d, crypttext_hash_tree=%d, block_hashes=%d, share_hashes=%d, uri_extension=%d" % tuple(fields)) + self._received.remove(0, 4) # don't need this anymore + + # validate the offsets a bit + share_hashes_size = offsets["uri_extension"] - offsets["share_hashes"] + if share_hashes_size < 0 or share_hashes_size % (2+HASH_SIZE) != 0: + # the share hash chain is stored as (hashnum,hash) pairs + self.had_corruption = True + raise LayoutInvalid("share hashes malformed -- should be a" + " multiple of %d bytes -- not %d" % + (2+HASH_SIZE, share_hashes_size)) + block_hashes_size = offsets["share_hashes"] - offsets["block_hashes"] + if block_hashes_size < 0 or block_hashes_size % (HASH_SIZE) != 0: + # the block hash tree is stored as a list of hashes + self.had_corruption = True + raise LayoutInvalid("block hashes malformed -- should be a" + " multiple of %d bytes -- not %d" % + (HASH_SIZE, block_hashes_size)) + # we only look at 'crypttext_hash_tree' if the UEB says we're + # actually using it. Same with 'plaintext_hash_tree'. This gives us + # some wiggle room: a place to stash data for later extensions. + + return True + + def _satisfy_UEB(self): + o = self.actual_offsets + fsize = self._fieldsize + UEB_length_s = self._received.get(o["uri_extension"], fsize) + if not UEB_length_s: + return False + (UEB_length,) = struct.unpack(">"+self._fieldstruct, UEB_length_s) + UEB_s = self._received.pop(o["uri_extension"]+fsize, UEB_length) + if not UEB_s: + return False + self._received.remove(o["uri_extension"], fsize) + try: + self._node.validate_and_store_UEB(UEB_s) + return True + except (LayoutInvalid, BadHashError), e: + # TODO: if this UEB was bad, we'll keep trying to validate it + # over and over again. Only log.err on the first one, or better + # yet skip all but the first + f = Failure(e) + self._signal_corruption(f, o["uri_extension"], fsize+UEB_length) + self.had_corruption = True + raise + + def _satisfy_share_hash_tree(self): + # the share hash chain is stored as (hashnum,hash) tuples, so you + # can't fetch just the pieces you need, because you don't know + # exactly where they are. So fetch everything, and parse the results + # later. + o = self.actual_offsets + hashlen = o["uri_extension"] - o["share_hashes"] + assert hashlen % (2+HASH_SIZE) == 0 + hashdata = self._received.get(o["share_hashes"], hashlen) + if not hashdata: + return False + share_hashes = {} + for i in range(0, hashlen, 2+HASH_SIZE): + (hashnum,) = struct.unpack(">H", hashdata[i:i+2]) + hashvalue = hashdata[i+2:i+2+HASH_SIZE] + share_hashes[hashnum] = hashvalue + # TODO: if they give us an empty set of hashes, + # process_share_hashes() won't fail. We must ensure that this + # situation doesn't allow unverified shares through. Manual testing + # shows that set_block_hash_root() throws an assert because an + # internal node is None instead of an actual hash, but we want + # something better. It's probably best to add a method to + # IncompleteHashTree which takes a leaf number and raises an + # exception unless that leaf is present and fully validated. + try: + self._node.process_share_hashes(share_hashes) + # adds to self._node.share_hash_tree + except (BadHashError, NotEnoughHashesError), e: + f = Failure(e) + self._signal_corruption(f, o["share_hashes"], hashlen) + self.had_corruption = True + raise + self._received.remove(o["share_hashes"], hashlen) + return True + + def _signal_corruption(self, f, start, offset): + # there was corruption somewhere in the given range + reason = "corruption in share[%d-%d): %s" % (start, start+offset, + str(f.value)) + self._rref.callRemoteOnly("advise_corrupt_share", reason) + + def _satisfy_block_hash_tree(self, needed_hashes): + o_bh = self.actual_offsets["block_hashes"] + block_hashes = {} + for hashnum in needed_hashes: + hashdata = self._received.get(o_bh+hashnum*HASH_SIZE, HASH_SIZE) + if hashdata: + block_hashes[hashnum] = hashdata + else: + return False # missing some hashes + # note that we don't submit any hashes to the block_hash_tree until + # we've gotten them all, because the hash tree will throw an + # exception if we only give it a partial set (which it therefore + # cannot validate) + try: + self._commonshare.process_block_hashes(block_hashes) + except (BadHashError, NotEnoughHashesError), e: + f = Failure(e) + hashnums = ",".join([str(n) for n in sorted(block_hashes.keys())]) + log.msg(format="hash failure in block_hashes=(%(hashnums)s)," + " from %(share)s", + hashnums=hashnums, shnum=self._shnum, share=repr(self), + failure=f, level=log.WEIRD, parent=self._lp, umid="yNyFdA") + hsize = max(0, max(needed_hashes)) * HASH_SIZE + self._signal_corruption(f, o_bh, hsize) + self.had_corruption = True + raise + for hashnum in needed_hashes: + self._received.remove(o_bh+hashnum*HASH_SIZE, HASH_SIZE) + return True + + def _satisfy_ciphertext_hash_tree(self, needed_hashes): + start = self.actual_offsets["crypttext_hash_tree"] + hashes = {} + for hashnum in needed_hashes: + hashdata = self._received.get(start+hashnum*HASH_SIZE, HASH_SIZE) + if hashdata: + hashes[hashnum] = hashdata + else: + return False # missing some hashes + # we don't submit any hashes to the ciphertext_hash_tree until we've + # gotten them all + try: + self._node.process_ciphertext_hashes(hashes) + except (BadHashError, NotEnoughHashesError), e: + f = Failure(e) + hashnums = ",".join([str(n) for n in sorted(hashes.keys())]) + log.msg(format="hash failure in ciphertext_hashes=(%(hashnums)s)," + " from %(share)s", + hashnums=hashnums, share=repr(self), failure=f, + level=log.WEIRD, parent=self._lp, umid="iZI0TA") + hsize = max(0, max(needed_hashes))*HASH_SIZE + self._signal_corruption(f, start, hsize) + self.had_corruption = True + raise + for hashnum in needed_hashes: + self._received.remove(start+hashnum*HASH_SIZE, HASH_SIZE) + return True + + def _satisfy_data_block(self, segnum, observers): + tail = (segnum == self._node.num_segments-1) + datastart = self.actual_offsets["data"] + blockstart = datastart + segnum * self._node.block_size + blocklen = self._node.block_size + if tail: + blocklen = self._node.tail_block_size + + block = self._received.pop(blockstart, blocklen) + if not block: + log.msg("no data for block %s (want [%d:+%d])" % (repr(self), + blockstart, blocklen)) + return False + log.msg(format="%(share)s._satisfy_data_block [%(start)d:+%(length)d]", + share=repr(self), start=blockstart, length=blocklen, + level=log.NOISY, parent=self._lp, umid="uTDNZg") + # this block is being retired, either as COMPLETE or CORRUPT, since + # no further data reads will help + assert self._requested_blocks[0][0] == segnum + try: + self._commonshare.check_block(segnum, block) + # hurrah, we have a valid block. Deliver it. + for o in observers: + # goes to SegmentFetcher._block_request_activity + o.notify(state=COMPLETE, block=block) + except (BadHashError, NotEnoughHashesError), e: + # rats, we have a corrupt block. Notify our clients that they + # need to look elsewhere, and advise the server. Unlike + # corruption in other parts of the share, this doesn't cause us + # to abandon the whole share. + f = Failure(e) + log.msg(format="hash failure in block %(segnum)d, from %(share)s", + segnum=segnum, share=repr(self), failure=f, + level=log.WEIRD, parent=self._lp, umid="mZjkqA") + for o in observers: + o.notify(state=CORRUPT) + self._signal_corruption(f, blockstart, blocklen) + self.had_corruption = True + # in either case, we've retired this block + self._requested_blocks.pop(0) + # popping the request keeps us from turning around and wanting the + # block again right away + return True # got satisfaction + + def _desire(self): + segnum, observers = self._active_segnum_and_observers() # maybe None + + # 'want_it' is for data we merely want: we know that we don't really + # need it. This includes speculative reads, like the first 1KB of the + # share (for the offset table) and the first 2KB of the UEB. + # + # 'need_it' is for data that, if we have the real offset table, we'll + # need. If we are only guessing at the offset table, it's merely + # wanted. (The share is abandoned if we can't get data that we really + # need). + # + # 'gotta_gotta_have_it' is for data that we absolutely need, + # independent of whether we're still guessing about the offset table: + # the version number and the offset table itself. + # + # Mr. Popeil, I'm in trouble, need your assistance on the double. Aww.. + + desire = Spans(), Spans(), Spans() + (want_it, need_it, gotta_gotta_have_it) = desire + + self.actual_segment_size = self._node.segment_size # might be updated + o = self.actual_offsets or self.guessed_offsets + segsize = self.actual_segment_size or self.guessed_segment_size + r = self._node._calculate_sizes(segsize) + + if not self.actual_offsets: + # all _desire functions add bits to the three desire[] spans + self._desire_offsets(desire) + + # we can use guessed offsets as long as this server tolerates + # overrun. Otherwise, we must wait for the offsets to arrive before + # we try to read anything else. + if self.actual_offsets or self._overrun_ok: + if not self._node.have_UEB: + self._desire_UEB(desire, o) + # They might ask for a segment that doesn't look right. + # _satisfy() will catch+reject bad segnums once we know the UEB + # (and therefore segsize and numsegs), so we'll only fail this + # test if we're still guessing. We want to avoid asking the + # hashtrees for needed_hashes() for bad segnums. So don't enter + # _desire_hashes or _desire_data unless the segnum looks + # reasonable. + if segnum < r["num_segments"]: + # XXX somehow we're getting here for sh5. we don't yet know + # the actual_segment_size, we're still working off the guess. + # the ciphertext_hash_tree has been corrected, but the + # commonshare._block_hash_tree is still in the guessed state. + self._desire_share_hashes(desire, o) + if segnum is not None: + self._desire_block_hashes(desire, o, segnum) + self._desire_data(desire, o, r, segnum, segsize) + else: + log.msg("_desire: segnum(%d) looks wrong (numsegs=%d)" + % (segnum, r["num_segments"]), + level=log.UNUSUAL, parent=self._lp, umid="tuYRQQ") + + log.msg("end _desire: want_it=%s need_it=%s gotta=%s" + % (want_it.dump(), need_it.dump(), gotta_gotta_have_it.dump())) + if self.actual_offsets: + return (want_it, need_it+gotta_gotta_have_it) + else: + return (want_it+need_it, gotta_gotta_have_it) + + def _desire_offsets(self, desire): + (want_it, need_it, gotta_gotta_have_it) = desire + if self._overrun_ok: + # easy! this includes version number, sizes, and offsets + want_it.add(0, 1024) + return + + # v1 has an offset table that lives [0x0,0x24). v2 lives [0x0,0x44). + # To be conservative, only request the data that we know lives there, + # even if that means more roundtrips. + + gotta_gotta_have_it.add(0, 4) # version number, always safe + version_s = self._received.get(0, 4) + if not version_s: + return + (version,) = struct.unpack(">L", version_s) + # The code in _satisfy_offsets will have checked this version + # already. There is no code path to get this far with version>2. + assert 1 <= version <= 2, "can't get here, version=%d" % version + if version == 1: + table_start = 0x0c + fieldsize = 0x4 + elif version == 2: + table_start = 0x14 + fieldsize = 0x8 + offset_table_size = 6 * fieldsize + gotta_gotta_have_it.add(table_start, offset_table_size) + + def _desire_UEB(self, desire, o): + (want_it, need_it, gotta_gotta_have_it) = desire + + # UEB data is stored as (length,data). + if self._overrun_ok: + # We can pre-fetch 2kb, which should probably cover it. If it + # turns out to be larger, we'll come back here later with a known + # length and fetch the rest. + want_it.add(o["uri_extension"], 2048) + # now, while that is probably enough to fetch the whole UEB, it + # might not be, so we need to do the next few steps as well. In + # most cases, the following steps will not actually add anything + # to need_it + + need_it.add(o["uri_extension"], self._fieldsize) + # only use a length if we're sure it's correct, otherwise we'll + # probably fetch a huge number + if not self.actual_offsets: + return + UEB_length_s = self._received.get(o["uri_extension"], self._fieldsize) + if UEB_length_s: + (UEB_length,) = struct.unpack(">"+self._fieldstruct, UEB_length_s) + # we know the length, so make sure we grab everything + need_it.add(o["uri_extension"]+self._fieldsize, UEB_length) + + def _desire_share_hashes(self, desire, o): + (want_it, need_it, gotta_gotta_have_it) = desire + + if self._node.share_hash_tree.needed_hashes(self._shnum): + hashlen = o["uri_extension"] - o["share_hashes"] + need_it.add(o["share_hashes"], hashlen) + + def _desire_block_hashes(self, desire, o, segnum): + (want_it, need_it, gotta_gotta_have_it) = desire + + # block hash chain + for hashnum in self._commonshare.get_needed_block_hashes(segnum): + need_it.add(o["block_hashes"]+hashnum*HASH_SIZE, HASH_SIZE) + + # ciphertext hash chain + for hashnum in self._node.get_needed_ciphertext_hashes(segnum): + need_it.add(o["crypttext_hash_tree"]+hashnum*HASH_SIZE, HASH_SIZE) + + def _desire_data(self, desire, o, r, segnum, segsize): + (want_it, need_it, gotta_gotta_have_it) = desire + tail = (segnum == r["num_segments"]-1) + datastart = o["data"] + blockstart = datastart + segnum * r["block_size"] + blocklen = r["block_size"] + if tail: + blocklen = r["tail_block_size"] + need_it.add(blockstart, blocklen) + + def _send_requests(self, desired): + ask = desired - self._pending - self._received.get_spans() + log.msg("%s._send_requests, desired=%s, pending=%s, ask=%s" % + (repr(self), desired.dump(), self._pending.dump(), ask.dump()), + level=log.NOISY, parent=self._lp, umid="E94CVA") + # XXX At one time, this code distinguished between data blocks and + # hashes, and made sure to send (small) requests for hashes before + # sending (big) requests for blocks. The idea was to make sure that + # all hashes arrive before the blocks, so the blocks can be consumed + # and released in a single turn. I removed this for simplicity. + # Reconsider the removal: maybe bring it back. + ds = self._download_status + + for (start, length) in ask: + # TODO: quantize to reasonably-large blocks + self._pending.add(start, length) + lp = log.msg(format="%(share)s._send_request" + " [%(start)d:+%(length)d]", + share=repr(self), + start=start, length=length, + level=log.NOISY, parent=self._lp, umid="sgVAyA") + req_ev = ds.add_request_sent(self._peerid, self._shnum, + start, length, now()) + d = self._send_request(start, length) + d.addCallback(self._got_data, start, length, req_ev, lp) + d.addErrback(self._got_error, start, length, req_ev, lp) + d.addCallback(self._trigger_loop) + d.addErrback(lambda f: + log.err(format="unhandled error during send_request", + failure=f, parent=self._lp, + level=log.WEIRD, umid="qZu0wg")) + + def _send_request(self, start, length): + return self._rref.callRemote("read", start, length) + + def _got_data(self, data, start, length, req_ev, lp): + req_ev.finished(len(data), now()) + if not self._alive: + return + log.msg(format="%(share)s._got_data [%(start)d:+%(length)d] -> %(datalen)d", + share=repr(self), start=start, length=length, datalen=len(data), + level=log.NOISY, parent=lp, umid="5Qn6VQ") + self._pending.remove(start, length) + self._received.add(start, data) + + # if we ask for [a:c], and we get back [a:b] (b