From: david-sarah Date: Wed, 27 Oct 2010 04:33:02 +0000 (-0700) Subject: make ResponseCache smarter to avoid memory leaks: don't record timestamps, use DataSp... X-Git-Tag: trac-4800~28 X-Git-Url: https://git.rkrishnan.org/frontends/specifications/reliability?a=commitdiff_plain;h=4061258c85da2960f1389dd4b4a8012087b92083;p=tahoe-lafs%2Ftahoe-lafs.git make ResponseCache smarter to avoid memory leaks: don't record timestamps, use DataSpans to merge entries, and clear the cache when we see a new seqnum. refs #1045, #1229 --- diff --git a/src/allmydata/mutable/common.py b/src/allmydata/mutable/common.py index e154b9df..29656be4 100644 --- a/src/allmydata/mutable/common.py +++ b/src/allmydata/mutable/common.py @@ -1,6 +1,6 @@ from allmydata.util import idlib -from allmydata.util.dictutil import DictOfSets +from allmydata.util.spans import DataSpans MODE_CHECK = "MODE_CHECK" # query all peers MODE_ANYTHING = "MODE_ANYTHING" # one recoverable version @@ -59,74 +59,52 @@ class UnknownVersionError(Exception): class ResponseCache: """I cache share data, to reduce the number of round trips used during mutable file operations. All of the data in my cache is for a single - storage index, but I will keep information on multiple shares (and - multiple versions) for that storage index. + storage index, but I will keep information on multiple shares for + that storage index. + + I maintain a highest-seen sequence number, and will flush all entries + each time this number increases (this doesn't necessarily imply that + all entries have the same sequence number). My cache is indexed by a (verinfo, shnum) tuple. - My cache entries contain a set of non-overlapping byteranges: (start, - data, timestamp) tuples. + My cache entries are DataSpans instances, each representing a set of + non-overlapping byteranges. """ def __init__(self): - self.cache = DictOfSets() + self.cache = {} + self.seqnum = None def _clear(self): - # used by unit tests - self.cache = DictOfSets() - - def _does_overlap(self, x_start, x_length, y_start, y_length): - if x_start < y_start: - x_start, y_start = y_start, x_start - x_length, y_length = y_length, x_length - x_end = x_start + x_length - y_end = y_start + y_length - # this just returns a boolean. Eventually we'll want a form that - # returns a range. - if not x_length: - return False - if not y_length: - return False - if x_start >= y_end: - return False - if y_start >= x_end: - return False - return True - - - def _inside(self, x_start, x_length, y_start, y_length): - x_end = x_start + x_length - y_end = y_start + y_length - if x_start < y_start: - return False - if x_start >= y_end: - return False - if x_end < y_start: - return False - if x_end > y_end: - return False - return True - - def add(self, verinfo, shnum, offset, data, timestamp): + # also used by unit tests + self.cache = {} + + def add(self, verinfo, shnum, offset, data): + seqnum = verinfo[0] + if seqnum > self.seqnum: + self._clear() + self.seqnum = seqnum + index = (verinfo, shnum) - self.cache.add(index, (offset, data, timestamp) ) + if index in self.cache: + self.cache[index].add(offset, data) + else: + spans = DataSpans() + spans.add(offset, data) + self.cache[index] = spans def read(self, verinfo, shnum, offset, length): """Try to satisfy a read request from cache. - Returns (data, timestamp), or (None, None) if the cache did not hold - the requested data. + Returns data, or None if the cache did not hold the entire requested span. """ - # TODO: join multiple fragments, instead of only returning a hit if - # we have a fragment that contains the whole request + # TODO: perhaps return a DataSpans object representing the fragments + # that we have, instead of only returning a hit if we can satisfy the + # whole request from cache. index = (verinfo, shnum) - for entry in self.cache.get(index, set()): - (e_start, e_data, e_timestamp) = entry - if self._inside(offset, length, e_start, len(e_data)): - want_start = offset - e_start - want_end = offset+length - e_start - return (e_data[want_start:want_end], e_timestamp) - return None, None - - + if index in self.cache: + return self.cache[index].get(offset, length) + else: + return None diff --git a/src/allmydata/mutable/filenode.py b/src/allmydata/mutable/filenode.py index d9cd9274..6c38a856 100644 --- a/src/allmydata/mutable/filenode.py +++ b/src/allmydata/mutable/filenode.py @@ -149,8 +149,8 @@ class MutableFileNode: self._privkey = privkey def _populate_encprivkey(self, encprivkey): self._encprivkey = encprivkey - def _add_to_cache(self, verinfo, shnum, offset, data, timestamp): - self._cache.add(verinfo, shnum, offset, data, timestamp) + def _add_to_cache(self, verinfo, shnum, offset, data): + self._cache.add(verinfo, shnum, offset, data) def _read_from_cache(self, verinfo, shnum, offset, length): return self._cache.read(verinfo, shnum, offset, length) diff --git a/src/allmydata/mutable/publish.py b/src/allmydata/mutable/publish.py index 1b7e050a..2d63c87b 100644 --- a/src/allmydata/mutable/publish.py +++ b/src/allmydata/mutable/publish.py @@ -7,12 +7,13 @@ from twisted.internet import defer from twisted.python import failure from allmydata.interfaces import IPublishStatus from allmydata.util import base32, hashutil, mathutil, idlib, log +from allmydata.util.dictutil import DictOfSets from allmydata import hashtree, codec from allmydata.storage.server import si_b2a from pycryptopp.cipher.aes import AES from foolscap.api import eventually, fireEventually -from allmydata.mutable.common import MODE_WRITE, MODE_CHECK, DictOfSets, \ +from allmydata.mutable.common import MODE_WRITE, MODE_CHECK, \ UncoordinatedWriteError, NotEnoughServersError from allmydata.mutable.servermap import ServerMap from allmydata.mutable.layout import pack_prefix, pack_share, unpack_header, pack_checkstring, \ diff --git a/src/allmydata/mutable/retrieve.py b/src/allmydata/mutable/retrieve.py index b4fa1c22..257cc5f3 100644 --- a/src/allmydata/mutable/retrieve.py +++ b/src/allmydata/mutable/retrieve.py @@ -7,12 +7,13 @@ from twisted.python import failure from foolscap.api import DeadReferenceError, eventually, fireEventually from allmydata.interfaces import IRetrieveStatus, NotEnoughSharesError from allmydata.util import hashutil, idlib, log +from allmydata.util.dictutil import DictOfSets from allmydata import hashtree, codec from allmydata.storage.server import si_b2a from pycryptopp.cipher.aes import AES from pycryptopp.publickey import rsa -from allmydata.mutable.common import DictOfSets, CorruptShareError, UncoordinatedWriteError +from allmydata.mutable.common import CorruptShareError, UncoordinatedWriteError from allmydata.mutable.layout import SIGNED_PREFIX, unpack_share_data class RetrieveStatus: @@ -198,8 +199,7 @@ class Retrieve: got_from_cache = False datavs = [] for (offset, length) in readv: - (data, timestamp) = self._node._read_from_cache(self.verinfo, shnum, - offset, length) + data = self._node._read_from_cache(self.verinfo, shnum, offset, length) if data is not None: datavs.append(data) if len(datavs) == len(readv): diff --git a/src/allmydata/mutable/servermap.py b/src/allmydata/mutable/servermap.py index 6478afcb..999691fa 100644 --- a/src/allmydata/mutable/servermap.py +++ b/src/allmydata/mutable/servermap.py @@ -6,12 +6,13 @@ from twisted.internet import defer from twisted.python import failure from foolscap.api import DeadReferenceError, RemoteException, eventually from allmydata.util import base32, hashutil, idlib, log +from allmydata.util.dictutil import DictOfSets from allmydata.storage.server import si_b2a from allmydata.interfaces import IServermapUpdaterStatus from pycryptopp.publickey import rsa from allmydata.mutable.common import MODE_CHECK, MODE_ANYTHING, MODE_WRITE, MODE_READ, \ - DictOfSets, CorruptShareError, NeedMoreDataError + CorruptShareError, NeedMoreDataError from allmydata.mutable.layout import unpack_prefix_and_signature, unpack_header, unpack_share, \ SIGNED_PREFIX_LENGTH @@ -581,7 +582,7 @@ class ServermapUpdater: verinfo = self._got_results_one_share(shnum, data, peerid, lp) last_verinfo = verinfo last_shnum = shnum - self._node._add_to_cache(verinfo, shnum, 0, data, now) + self._node._add_to_cache(verinfo, shnum, 0, data) except CorruptShareError, e: # log it and give the other shares a chance to be processed f = failure.Failure() diff --git a/src/allmydata/test/test_mutable.py b/src/allmydata/test/test_mutable.py index 375de1ff..e4e6eb7f 100644 --- a/src/allmydata/test/test_mutable.py +++ b/src/allmydata/test/test_mutable.py @@ -301,16 +301,16 @@ class Filenode(unittest.TestCase, testutil.ShouldFailMixin): d.addCallback(lambda res: self.failUnlessEqual(res, "contents")) d.addCallback(lambda ign: self.failUnless(isinstance(n._cache, ResponseCache))) - def _check_cache_size(expected): - # The total size of cache entries should not increase on the second download. + def _check_cache(expected): + # The total size of cache entries should not increase on the second download; + # in fact the cache contents should be identical. d2 = n.download_best_version() - d2.addCallback(lambda ign: self.failUnlessEqual(len(repr(n._cache.cache)), expected)) + d2.addCallback(lambda rep: self.failUnlessEqual(repr(n._cache.cache), expected)) return d2 - d.addCallback(lambda ign: _check_cache_size(len(repr(n._cache.cache)))) + d.addCallback(lambda ign: _check_cache(repr(n._cache.cache))) return d d.addCallback(_created) return d - test_response_cache_memory_leak.todo = "This isn't fixed (see #1045)." def test_create_with_initial_contents_function(self): data = "initial contents" @@ -1717,72 +1717,37 @@ class MultipleVersions(unittest.TestCase, PublishMixin, CheckerMixin): class Utils(unittest.TestCase): - def _do_inside(self, c, x_start, x_length, y_start, y_length): - # we compare this against sets of integers - x = set(range(x_start, x_start+x_length)) - y = set(range(y_start, y_start+y_length)) - should_be_inside = x.issubset(y) - self.failUnlessEqual(should_be_inside, c._inside(x_start, x_length, - y_start, y_length), - str((x_start, x_length, y_start, y_length))) - - def test_cache_inside(self): - c = ResponseCache() - x_start = 10 - x_length = 5 - for y_start in range(8, 17): - for y_length in range(8): - self._do_inside(c, x_start, x_length, y_start, y_length) - - def _do_overlap(self, c, x_start, x_length, y_start, y_length): - # we compare this against sets of integers - x = set(range(x_start, x_start+x_length)) - y = set(range(y_start, y_start+y_length)) - overlap = bool(x.intersection(y)) - self.failUnlessEqual(overlap, c._does_overlap(x_start, x_length, - y_start, y_length), - str((x_start, x_length, y_start, y_length))) - - def test_cache_overlap(self): - c = ResponseCache() - x_start = 10 - x_length = 5 - for y_start in range(8, 17): - for y_length in range(8): - self._do_overlap(c, x_start, x_length, y_start, y_length) - def test_cache(self): c = ResponseCache() # xdata = base62.b2a(os.urandom(100))[:100] xdata = "1Ex4mdMaDyOl9YnGBM3I4xaBF97j8OQAg1K3RBR01F2PwTP4HohB3XpACuku8Xj4aTQjqJIR1f36mEj3BCNjXaJmPBEZnnHL0U9l" ydata = "4DCUQXvkEPnnr9Lufikq5t21JsnzZKhzxKBhLhrBB6iIcBOWRuT4UweDhjuKJUre8A4wOObJnl3Kiqmlj4vjSLSqUGAkUD87Y3vs" - nope = (None, None) - c.add("v1", 1, 0, xdata, "time0") - c.add("v1", 1, 2000, ydata, "time1") - self.failUnlessEqual(c.read("v2", 1, 10, 11), nope) - self.failUnlessEqual(c.read("v1", 2, 10, 11), nope) - self.failUnlessEqual(c.read("v1", 1, 0, 10), (xdata[:10], "time0")) - self.failUnlessEqual(c.read("v1", 1, 90, 10), (xdata[90:], "time0")) - self.failUnlessEqual(c.read("v1", 1, 300, 10), nope) - self.failUnlessEqual(c.read("v1", 1, 2050, 5), (ydata[50:55], "time1")) - self.failUnlessEqual(c.read("v1", 1, 0, 101), nope) - self.failUnlessEqual(c.read("v1", 1, 99, 1), (xdata[99:100], "time0")) - self.failUnlessEqual(c.read("v1", 1, 100, 1), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 9), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 10), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 11), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 15), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 19), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 20), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 21), nope) - self.failUnlessEqual(c.read("v1", 1, 1990, 25), nope) - self.failUnlessEqual(c.read("v1", 1, 1999, 25), nope) - - # optional: join fragments + c.add("v1", 1, 0, xdata) + c.add("v1", 1, 2000, ydata) + self.failUnlessEqual(c.read("v2", 1, 10, 11), None) + self.failUnlessEqual(c.read("v1", 2, 10, 11), None) + self.failUnlessEqual(c.read("v1", 1, 0, 10), xdata[:10]) + self.failUnlessEqual(c.read("v1", 1, 90, 10), xdata[90:]) + self.failUnlessEqual(c.read("v1", 1, 300, 10), None) + self.failUnlessEqual(c.read("v1", 1, 2050, 5), ydata[50:55]) + self.failUnlessEqual(c.read("v1", 1, 0, 101), None) + self.failUnlessEqual(c.read("v1", 1, 99, 1), xdata[99:100]) + self.failUnlessEqual(c.read("v1", 1, 100, 1), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 9), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 10), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 11), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 15), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 19), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 20), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 21), None) + self.failUnlessEqual(c.read("v1", 1, 1990, 25), None) + self.failUnlessEqual(c.read("v1", 1, 1999, 25), None) + + # test joining fragments c = ResponseCache() - c.add("v1", 1, 0, xdata[:10], "time0") - c.add("v1", 1, 10, xdata[10:20], "time1") - #self.failUnlessEqual(c.read("v1", 1, 0, 20), (xdata[:20], "time0")) + c.add("v1", 1, 0, xdata[:10]) + c.add("v1", 1, 10, xdata[10:20]) + self.failUnlessEqual(c.read("v1", 1, 0, 20), xdata[:20]) class Exceptions(unittest.TestCase): def test_repr(self):