From: David-Sarah Hopwood Date: Tue, 19 Mar 2013 05:37:02 +0000 (+0000) Subject: Improve SFTP error handling and remove use of IFinishableConsumer. fixes #1525 X-Git-Tag: allmydata-tahoe-1.10a1~2 X-Git-Url: https://git.rkrishnan.org/%5B/%5D%20/uri/%22doc.html/architecture.txt?a=commitdiff_plain;h=50c6562901449427c1189890b9b8a1e4e5c81478;p=tahoe-lafs%2Ftahoe-lafs.git Improve SFTP error handling and remove use of IFinishableConsumer. fixes #1525 Signed-off-by: David-Sarah Hopwood --- diff --git a/src/allmydata/frontends/sftpd.py b/src/allmydata/frontends/sftpd.py index 4e16d6ab..f6e11ced 100644 --- a/src/allmydata/frontends/sftpd.py +++ b/src/allmydata/frontends/sftpd.py @@ -22,7 +22,7 @@ from twisted.python.failure import Failure from twisted.internet.interfaces import ITransport from twisted.internet import defer -from twisted.internet.interfaces import IFinishableConsumer +from twisted.internet.interfaces import IConsumer from foolscap.api import eventually from allmydata.util import deferredutil @@ -294,7 +294,7 @@ def _direntry_for(filenode_or_parent, childname, filenode=None): class OverwriteableFileConsumer(PrefixingLogMixin): - implements(IFinishableConsumer) + implements(IConsumer) """I act both as a consumer for the download of the original file contents, and as a wrapper for a temporary file that records the downloaded data and any overwrites. I use a priority queue to keep track of which regions of the file have been overwritten @@ -321,12 +321,9 @@ class OverwriteableFileConsumer(PrefixingLogMixin): self.milestones = [] # empty heap of (offset, d) self.overwrites = [] # empty heap of (start, end) self.is_closed = False - self.done = self.when_reached(download_size) # adds a milestone - self.is_done = False - def _signal_done(ign): - if noisy: self.log("DONE", level=NOISY) - self.is_done = True - self.done.addCallback(_signal_done) + + self.done = defer.Deferred() + self.done_status = None # None -> not complete, Failure -> download failed, str -> download succeeded self.producer = None def get_file(self): @@ -349,7 +346,7 @@ class OverwriteableFileConsumer(PrefixingLogMixin): self.download_size = size if self.downloaded >= self.download_size: - self.finish() + self.download_done("size changed") def registerProducer(self, p, streaming): if noisy: self.log(".registerProducer(%r, streaming=%r)" % (p, streaming), level=NOISY) @@ -362,7 +359,7 @@ class OverwriteableFileConsumer(PrefixingLogMixin): p.resumeProducing() else: def _iterate(): - if not self.is_done: + if self.done_status is None: p.resumeProducing() eventually(_iterate) _iterate() @@ -429,13 +426,17 @@ class OverwriteableFileConsumer(PrefixingLogMixin): return if noisy: self.log("MILESTONE %r %r" % (next, d), level=NOISY) heapq.heappop(self.milestones) - eventually(d.callback, None) + eventually_callback(d)("reached") if milestone >= self.download_size: - self.finish() + self.download_done("reached download size") def overwrite(self, offset, data): if noisy: self.log(".overwrite(%r, )" % (offset, len(data)), level=NOISY) + if self.is_closed: + self.log("overwrite called on a closed OverwriteableFileConsumer", level=WEIRD) + raise SFTPError(FX_BAD_MESSAGE, "cannot write to a closed file handle") + if offset > self.current_size: # Normally writing at an offset beyond the current end-of-file # would leave a hole that appears filled with zeroes. However, an @@ -463,6 +464,9 @@ class OverwriteableFileConsumer(PrefixingLogMixin): The caller must perform no more overwrites until the Deferred has fired.""" if noisy: self.log(".read(%r, %r), current_size = %r" % (offset, length, self.current_size), level=NOISY) + if self.is_closed: + self.log("read called on a closed OverwriteableFileConsumer", level=WEIRD) + raise SFTPError(FX_BAD_MESSAGE, "cannot read from a closed file handle") # Note that the overwrite method is synchronous. When a write request is processed # (e.g. a writeChunk request on the async queue of GeneralSFTPFile), overwrite will @@ -478,48 +482,68 @@ class OverwriteableFileConsumer(PrefixingLogMixin): if noisy: self.log("truncating read to %r bytes" % (length,), level=NOISY) needed = min(offset + length, self.download_size) - d = self.when_reached(needed) - def _reached(ign): + + # If we fail to reach the needed number of bytes, the read request will fail. + d = self.when_reached_or_failed(needed) + def _reached_in_read(res): # It is not necessarily the case that self.downloaded >= needed, because # the file might have been truncated (thus truncating the download) and # then extended. _assert(self.current_size >= offset + length, current_size=self.current_size, offset=offset, length=length) - if noisy: self.log("self.f = %r" % (self.f,), level=NOISY) + if noisy: self.log("_reached_in_read(%r), self.f = %r" % (res, self.f,), level=NOISY) self.f.seek(offset) return self.f.read(length) - d.addCallback(_reached) + d.addCallback(_reached_in_read) return d - def when_reached(self, index): - if noisy: self.log(".when_reached(%r)" % (index,), level=NOISY) - if index <= self.downloaded: # already reached - if noisy: self.log("already reached %r" % (index,), level=NOISY) - return defer.succeed(None) + def when_reached_or_failed(self, index): + if noisy: self.log(".when_reached_or_failed(%r)" % (index,), level=NOISY) + def _reached(res): + if noisy: self.log("reached %r with result %r" % (index, res), level=NOISY) + return res + + if self.done_status is not None: + return defer.execute(_reached, self.done_status) + if index <= self.downloaded: # already reached successfully + if noisy: self.log("already reached %r successfully" % (index,), level=NOISY) + return defer.succeed("already reached successfully") d = defer.Deferred() - def _reached(ign): - if noisy: self.log("reached %r" % (index,), level=NOISY) - return ign d.addCallback(_reached) heapq.heappush(self.milestones, (index, d)) return d def when_done(self): - return self.done + d = defer.Deferred() + self.done.addCallback(lambda ign: eventually_callback(d)(self.done_status)) + return d - def finish(self): - """Called by the producer when it has finished producing, or when we have - received enough bytes, or as a result of a close. Defined by IFinishableConsumer.""" + def download_done(self, res): + _assert(isinstance(res, (str, Failure)), res=res) + # Only the first call to download_done counts, but we log subsequent calls + # (multiple calls are normal). + if self.done_status is not None: + self.log("IGNORING extra call to download_done with result %r; previous result was %r" + % (res, self.done_status), level=OPERATIONAL) + return + + self.log("DONE with result %r" % (res,), level=OPERATIONAL) + + # We avoid errbacking self.done so that we are not left with an 'Unhandled error in Deferred' + # in case when_done() is never called. Instead we stash the failure in self.done_status, + # from where the callback added in when_done() can retrieve it. + self.done_status = res + eventually_callback(self.done)(None) while len(self.milestones) > 0: (next, d) = self.milestones[0] - if noisy: self.log("MILESTONE FINISH %r %r" % (next, d), level=NOISY) + if noisy: self.log("MILESTONE FINISH %r %r %r" % (next, d, res), level=NOISY) heapq.heappop(self.milestones) # The callback means that the milestone has been reached if # it is ever going to be. Note that the file may have been # truncated to before the milestone. - eventually(d.callback, None) + eventually_callback(d)(res) def close(self): if not self.is_closed: @@ -528,10 +552,14 @@ class OverwriteableFileConsumer(PrefixingLogMixin): self.f.close() except Exception, e: self.log("suppressed %r from close of temporary file %r" % (e, self.f), level=WEIRD) - self.finish() + self.download_done("closed") + return self.done_status def unregisterProducer(self): - pass + # This will happen just before our client calls download_done, which will tell + # us the outcome of the download; we don't know the outcome at this point. + self.producer = None + self.log("producer unregistered", level=NOISY) SIZE_THRESHOLD = 1000 @@ -577,9 +605,9 @@ class ShortReadOnlySFTPFile(PrefixingLogMixin): # i.e. we respond with an EOF error iff offset is already at EOF. if offset >= len(data): - eventually(d.errback, SFTPError(FX_EOF, "read at or past end of file")) + eventually_errback(d)(Failure(SFTPError(FX_EOF, "read at or past end of file"))) else: - eventually(d.callback, data[offset:offset+length]) # truncated if offset+length > len(data) + eventually_callback(d)(data[offset:offset+length]) # truncated if offset+length > len(data) return data self.async.addCallbacks(_read, eventually_errback(d)) d.addBoth(_convert_error, request) @@ -672,7 +700,7 @@ class GeneralSFTPFile(PrefixingLogMixin): if (self.flags & FXF_TRUNC) or not filenode: # We're either truncating or creating the file, so we don't need the old contents. self.consumer = OverwriteableFileConsumer(0, tempfile_maker) - self.consumer.finish() + self.consumer.download_done("download not needed") else: self.async.addCallback(lambda ignored: filenode.get_best_readable_version()) @@ -683,10 +711,16 @@ class GeneralSFTPFile(PrefixingLogMixin): self.consumer = OverwriteableFileConsumer(download_size, tempfile_maker) - version.read(self.consumer, 0, None) + d = version.read(self.consumer, 0, None) + def _finished(res): + if not isinstance(res, Failure): + res = "download finished" + self.consumer.download_done(res) + d.addBoth(_finished) + # It is correct to drop d here. self.async.addCallback(_read) - eventually(self.async.callback, None) + eventually_callback(self.async)(None) if noisy: self.log("open done", level=NOISY) return self @@ -739,7 +773,7 @@ class GeneralSFTPFile(PrefixingLogMixin): def _read(ign): if noisy: self.log("_read in readChunk(%r, %r)" % (offset, length), level=NOISY) d2 = self.consumer.read(offset, length) - d2.addCallbacks(eventually_callback(d), eventually_errback(d)) + d2.addBoth(eventually_callback(d)) # It is correct to drop d2 here. return None self.async.addCallbacks(_read, eventually_errback(d)) @@ -783,6 +817,24 @@ class GeneralSFTPFile(PrefixingLogMixin): # don't addErrback to self.async, just allow subsequent async ops to fail. return defer.succeed(None) + def _do_close(self, res, d=None): + if noisy: self.log("_do_close(%r)" % (res,), level=NOISY) + status = None + if self.consumer: + status = self.consumer.close() + + # We must close_notify before re-firing self.async. + if self.close_notify: + self.close_notify(self.userpath, self.parent, self.childname, self) + + if not isinstance(res, Failure) and isinstance(status, Failure): + res = status + + if d: + eventually_callback(d)(res) + elif isinstance(res, Failure): + self.log("suppressing %r" % (res,), level=OPERATIONAL) + def close(self): request = ".close()" self.log(request, level=OPERATIONAL) @@ -794,10 +846,14 @@ class GeneralSFTPFile(PrefixingLogMixin): self.closed = True if not (self.flags & (FXF_WRITE | FXF_CREAT)): - def _readonly_close(): - if self.consumer: - self.consumer.close() - return defer.execute(_readonly_close) + # We never fail a close of a handle opened only for reading, even if the file + # failed to download. (We could not do so deterministically, because it would + # depend on whether we reached the point of failure before abandoning the + # download.) Any reads that depended on file content that could not be downloaded + # will have failed. It is important that we don't close the consumer until + # previous read operations have completed. + self.async.addBoth(self._do_close) + return defer.succeed(None) # We must capture the abandoned, parent, and childname variables synchronously # at the close call. This is needed by the correctness arguments in the comments @@ -811,20 +867,11 @@ class GeneralSFTPFile(PrefixingLogMixin): # it is correct to optimize out the commit if it is False at the close call. has_changed = self.has_changed - def _committed(res): - if noisy: self.log("_committed(%r)" % (res,), level=NOISY) - - self.consumer.close() - - # We must close_notify before re-firing self.async. - if self.close_notify: - self.close_notify(self.userpath, self.parent, self.childname, self) - return res - - def _close(ign): + def _commit(ign): d2 = self.consumer.when_done() if self.filenode and self.filenode.is_mutable(): - self.log("update mutable file %r childname=%r metadata=%r" % (self.filenode, childname, self.metadata), level=OPERATIONAL) + self.log("update mutable file %r childname=%r metadata=%r" + % (self.filenode, childname, self.metadata), level=OPERATIONAL) if self.metadata.get('no-write', False) and not self.filenode.is_readonly(): _assert(parent and childname, parent=parent, childname=childname, metadata=self.metadata) d2.addCallback(lambda ign: parent.set_metadata_for(childname, self.metadata)) @@ -836,22 +883,19 @@ class GeneralSFTPFile(PrefixingLogMixin): u = FileHandle(self.consumer.get_file(), self.convergence) return parent.add_file(childname, u, metadata=self.metadata) d2.addCallback(_add_file) - - d2.addBoth(_committed) return d2 - d = defer.Deferred() - # If the file has been abandoned, we don't want the close operation to get "stuck", - # even if self.async fails to re-fire. Doing the close independently of self.async - # in that case ensures that dropping an ssh connection is sufficient to abandon + # even if self.async fails to re-fire. Completing the close independently of self.async + # in that case should ensure that dropping an ssh connection is sufficient to abandon # any heisenfiles that were not explicitly closed in that connection. if abandoned or not has_changed: - d.addCallback(_committed) + d = defer.succeed(None) + self.async.addBoth(self._do_close) else: - self.async.addCallback(_close) - - self.async.addCallbacks(eventually_callback(d), eventually_errback(d)) + d = defer.Deferred() + self.async.addCallback(_commit) + self.async.addBoth(self._do_close, d) d.addBoth(_convert_error, request) return d @@ -873,7 +917,7 @@ class GeneralSFTPFile(PrefixingLogMixin): # self.filenode might be None, but that's ok. attrs = _populate_attrs(self.filenode, self.metadata, size=self.consumer.get_current_size()) - eventually(d.callback, attrs) + eventually_callback(d)(attrs) return None self.async.addCallbacks(_get, eventually_errback(d)) d.addBoth(_convert_error, request) @@ -911,7 +955,7 @@ class GeneralSFTPFile(PrefixingLogMixin): # TODO: should we refuse to truncate a file opened with FXF_APPEND? # self.consumer.set_current_size(size) - eventually(d.callback, None) + eventually_callback(d)(None) return None self.async.addCallbacks(_set, eventually_errback(d)) d.addBoth(_convert_error, request) diff --git a/src/allmydata/test/no_network.py b/src/allmydata/test/no_network.py index 67469842..7c904919 100644 --- a/src/allmydata/test/no_network.py +++ b/src/allmydata/test/no_network.py @@ -326,6 +326,13 @@ class NoNetworkGrid(service.MultiService): ss.hung_until.callback(None) ss.hung_until = None + def nuke_from_orbit(self): + """ Empty all share directories in this grid. It's the only way to be sure ;-) """ + for server in self.servers_by_number.values(): + for prefixdir in os.listdir(server.sharedir): + if prefixdir != 'incoming': + fileutil.rm_dir(os.path.join(server.sharedir, prefixdir)) + class GridTestMixin: def setUp(self): diff --git a/src/allmydata/test/test_sftp.py b/src/allmydata/test/test_sftp.py index a45d71d0..69fedce4 100644 --- a/src/allmydata/test/test_sftp.py +++ b/src/allmydata/test/test_sftp.py @@ -36,6 +36,10 @@ from allmydata.test.common_util import ReallyEqualMixin timeout = 240 +#defer.setDebugging(True) +#from twisted.internet import base +#base.DelayedCall.debug = True + class Handler(GridTestMixin, ShouldFailMixin, ReallyEqualMixin, unittest.TestCase): """This is a no-network unit test of the SFTPUserHandler and the abstractions it uses.""" @@ -519,6 +523,43 @@ class Handler(GridTestMixin, ShouldFailMixin, ReallyEqualMixin, unittest.TestCas return d2 d.addCallback(_read_short) + # check that failed downloads cause failed reads + d.addCallback(lambda ign: self.handler.openFile("uri/"+self.gross_uri, sftp.FXF_READ, {})) + def _read_broken(rf): + d2 = defer.succeed(None) + d2.addCallback(lambda ign: self.g.nuke_from_orbit()) + d2.addCallback(lambda ign: + self.shouldFailWithSFTPError(sftp.FX_FAILURE, "read broken", + rf.readChunk, 0, 100)) + # close shouldn't fail + d2.addCallback(lambda ign: rf.close()) + d2.addCallback(lambda res: self.failUnlessReallyEqual(res, None)) + return d2 + d.addCallback(_read_broken) + + d.addCallback(lambda ign: self.failUnlessEqual(sftpd.all_heisenfiles, {})) + d.addCallback(lambda ign: self.failUnlessEqual(self.handler._heisenfiles, {})) + return d + + def test_openFile_read_error(self): + # The check at the end of openFile_read tested this for large files, but it trashed + # the grid in the process, so this needs to be a separate test. + small = upload.Data("0123456789"*10, None) + d = self._set_up("openFile_read_error") + d.addCallback(lambda ign: self.root.add_file(u"small", small)) + d.addCallback(lambda n: self.handler.openFile("/uri/"+n.get_uri(), sftp.FXF_READ, {})) + def _read_broken(rf): + d2 = defer.succeed(None) + d2.addCallback(lambda ign: self.g.nuke_from_orbit()) + d2.addCallback(lambda ign: + self.shouldFailWithSFTPError(sftp.FX_FAILURE, "read broken", + rf.readChunk, 0, 100)) + # close shouldn't fail + d2.addCallback(lambda ign: rf.close()) + d2.addCallback(lambda res: self.failUnlessReallyEqual(res, None)) + return d2 + d.addCallback(_read_broken) + d.addCallback(lambda ign: self.failUnlessEqual(sftpd.all_heisenfiles, {})) d.addCallback(lambda ign: self.failUnlessEqual(self.handler._heisenfiles, {})) return d @@ -982,6 +1023,24 @@ class Handler(GridTestMixin, ShouldFailMixin, ReallyEqualMixin, unittest.TestCas self.shouldFail(NoSuchChildError, "rename new while open", "new", self.root.get, u"new")) + # check that failed downloads cause failed reads and failed close, when open for writing + gross = u"gro\u00DF".encode("utf-8") + d.addCallback(lambda ign: self.handler.openFile(gross, sftp.FXF_READ | sftp.FXF_WRITE, {})) + def _read_write_broken(rwf): + d2 = rwf.writeChunk(0, "abcdefghij") + d2.addCallback(lambda ign: self.g.nuke_from_orbit()) + + # reading should fail (reliably if we read past the written chunk) + d2.addCallback(lambda ign: + self.shouldFailWithSFTPError(sftp.FX_FAILURE, "read/write broken", + rwf.readChunk, 0, 100)) + # close should fail in this case + d2.addCallback(lambda ign: + self.shouldFailWithSFTPError(sftp.FX_FAILURE, "read/write broken close", + rwf.close)) + return d2 + d.addCallback(_read_write_broken) + d.addCallback(lambda ign: self.failUnlessEqual(sftpd.all_heisenfiles, {})) d.addCallback(lambda ign: self.failUnlessEqual(self.handler._heisenfiles, {})) return d