from allmydata.interfaces import IRetrieveStatus, NotEnoughSharesError, \
DownloadStopped, MDMF_VERSION, SDMF_VERSION
-from allmydata.util.assertutil import _assert
+from allmydata.util.assertutil import _assert, precondition
from allmydata.util import hashutil, log, mathutil, deferredutil
from allmydata.util.dictutil import DictOfSets
from allmydata import hashtree, codec
self.servermap = servermap
assert self._node.get_pubkey()
self.verinfo = verinfo
+ # TODO: make it possible to use self.verinfo.datalength instead
+ (seqnum, root_hash, IV, segsize, datalength, k, N, prefix,
+ offsets_tuple) = self.verinfo
+ self._data_length = datalength
# during repair, we may be called upon to grab the private key, since
# it wasn't picked up during a verify=False checker run, and we'll
# need it for repair to generate a new version.
self._status.set_helper(False)
self._status.set_progress(0.0)
self._status.set_active(True)
- (seqnum, root_hash, IV, segsize, datalength, k, N, prefix,
- offsets_tuple) = self.verinfo
self._status.set_size(datalength)
self._status.set_encoding(k, N)
self.readers = {}
def download(self, consumer=None, offset=0, size=None):
- assert IConsumer.providedBy(consumer) or self._verify
-
+ precondition(self._verify or IConsumer.providedBy(consumer))
+ if size is None:
+ size = self._data_length - offset
+ if self._verify:
+ _assert(size == self._data_length, (size, self._data_length))
+ self.log("starting download")
+ self._done_deferred = defer.Deferred()
if consumer:
self._consumer = consumer
- # we provide IPushProducer, so streaming=True, per
- # IConsumer.
+ # we provide IPushProducer, so streaming=True, per IConsumer.
self._consumer.registerProducer(self, streaming=True)
+ self._started = time.time()
+ self._started_fetching = time.time()
+ if size == 0:
+ # short-circuit the rest of the process
+ self._done()
+ else:
+ self._start_download(consumer, offset, size)
+ return self._done_deferred
+
+ def _start_download(self, consumer, offset, size):
+ precondition((0 <= offset < self._data_length)
+ and (size > 0)
+ and (offset+size <= self._data_length),
+ (offset, size, self._data_length))
- self._done_deferred = defer.Deferred()
self._offset = offset
self._read_length = size
self._setup_encoding_parameters()
self._setup_download()
- self.log("starting download")
- self._started_fetching = time.time()
+
# The download process beyond this is a state machine.
# _add_active_servers will select the servers that we want to use
# for the download, and then attempt to start downloading. After
# will errback. Otherwise, it will eventually callback with the
# contents of the mutable file.
self.loop()
- return self._done_deferred
def loop(self):
d = fireEventually(None) # avoid #237 recursion limit problem
d.addErrback(self._error)
def _setup_download(self):
- self._started = time.time()
self._status.set_status("Retrieving Shares")
# how many shares do we need?
"""
# We don't need the block hash trees in this case.
self._block_hash_trees = None
+ self._offset = 0
+ self._read_length = self._data_length
self._setup_encoding_parameters()
# _decode_blocks() expects the output of a gatherResults that
self._required_shares = k
self._total_shares = n
self._segment_size = segsize
- self._data_length = datalength
+ #self._data_length = datalength # set during __init__()
if not IV:
self._version = MDMF_VERSION
# offset we were given.
start = self._offset // self._segment_size
- _assert(start < self._num_segments,
+ _assert(start <= self._num_segments,
start=start, num_segments=self._num_segments,
offset=self._offset, segment_size=self._segment_size)
self._start_segment = start
else:
self._start_segment = 0
-
- # If self._read_length is None, then we want to read the whole
- # file. Otherwise, we want to read only part of the file, and
- # need to figure out where to stop reading.
- if self._read_length is not None:
- # our end segment is the last segment containing part of the
- # segment that we were asked to read.
- self.log("got read length %d" % self._read_length)
- if self._read_length != 0:
- end_data = self._offset + self._read_length
-
- # We don't actually need to read the byte at end_data,
- # but the one before it.
- end = (end_data - 1) // self._segment_size
-
- _assert(end < self._num_segments,
- end=end, num_segments=self._num_segments,
- end_data=end_data, offset=self._offset, read_length=self._read_length,
- segment_size=self._segment_size)
- self._last_segment = end
- else:
- self._last_segment = self._start_segment
- self.log("got end segment: %d" % self._last_segment)
- else:
- self._last_segment = self._num_segments - 1
+ # We might want to read only part of the file, and need to figure out
+ # where to stop reading. Our end segment is the last segment
+ # containing part of the segment that we were asked to read.
+ _assert(self._read_length > 0, self._read_length)
+ end_data = self._offset + self._read_length
+
+ # We don't actually need to read the byte at end_data, but the one
+ # before it.
+ end = (end_data - 1) // self._segment_size
+ _assert(0 <= end < self._num_segments,
+ end=end, num_segments=self._num_segments,
+ end_data=end_data, offset=self._offset,
+ read_length=self._read_length, segment_size=self._segment_size)
+ self._last_segment = end
+ self.log("got end segment: %d" % self._last_segment)
self._current_segment = self._start_segment
I download, validate, decode, decrypt, and assemble the segment
that this Retrieve is currently responsible for downloading.
"""
+
if self._current_segment > self._last_segment:
# No more segments to download, we're done.
self.log("got plaintext, done")
target that is handling the file download.
"""
self.log("got plaintext for segment %d" % self._current_segment)
+
+ if self._read_length == 0:
+ self.log("on first+last segment, size=0, using 0 bytes")
+ segment = b""
+
+ if self._current_segment == self._last_segment:
+ # trim off the tail
+ wanted = (self._offset + self._read_length) % self._segment_size
+ if wanted != 0:
+ self.log("on the last segment: using first %d bytes" % wanted)
+ segment = segment[:wanted]
+ else:
+ self.log("on the last segment: using all %d bytes" %
+ len(segment))
+
if self._current_segment == self._start_segment:
- # We're on the first segment. It's possible that we want
- # only some part of the end of this segment, and that we
- # just downloaded the whole thing to get that part. If so,
- # we need to account for that and give the reader just the
- # data that they want.
- n = self._offset % self._segment_size
- self.log("stripping %d bytes off of the first segment" % n)
- self.log("original segment length: %d" % len(segment))
- segment = segment[n:]
- self.log("new segment length: %d" % len(segment))
-
- if self._current_segment == self._last_segment and self._read_length is not None:
- # We're on the last segment. It's possible that we only want
- # part of the beginning of this segment, and that we
- # downloaded the whole thing anyway. Make sure to give the
- # caller only the portion of the segment that they want to
- # receive.
- extra = self._read_length
- if self._start_segment != self._last_segment:
- extra -= self._segment_size - \
- (self._offset % self._segment_size)
- extra %= self._segment_size
- self.log("original segment length: %d" % len(segment))
- segment = segment[:extra]
- self.log("new segment length: %d" % len(segment))
- self.log("only taking %d bytes of the last segment" % extra)
+ # Trim off the head, if offset != 0. This should also work if
+ # start==last, because we trim the tail first.
+ skip = self._offset % self._segment_size
+ self.log("on the first segment: skipping first %d bytes" % skip)
+ segment = segment[skip:]
if not self._verify:
self._consumer.write(segment)
projects / tahoe-lafs / tahoe-lafs.git / commitdiff