remotefilelog: prefetch files in deterministic order

I have been troubleshooting some slowness in this area (it's unclear
if it's the client or server that's to blame, but that's beside the
point) and it's a lot easier to do troubleshoot if the files are
prefetched in the same order each time.

Differential Revision: https://phab.mercurial-scm.org/D6172

hgext/remotefilelog/fileserverclient.py

@@ -1,581 +1,581 b''
 # fileserverclient.py - client for communicating with the cache process
 #
 # Copyright 2013 Facebook, Inc.
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import hashlib
 import io
 import os
 import threading
 import time
 import zlib
 
 from mercurial.i18n import _
 from mercurial.node import bin, hex, nullid
 from mercurial import (
     error,
     node,
     pycompat,
     revlog,
     sshpeer,
     util,
     wireprotov1peer,
 )
 from mercurial.utils import procutil
 
 from . import (
     constants,
     contentstore,
     metadatastore,
 )
 
 _sshv1peer = sshpeer.sshv1peer
 
 # Statistics for debugging
 fetchcost = 0
 fetches = 0
 fetched = 0
 fetchmisses = 0
 
 _lfsmod = None
 
 def getcachekey(reponame, file, id):
     pathhash = node.hex(hashlib.sha1(file).digest())
     return os.path.join(reponame, pathhash[:2], pathhash[2:], id)
 
 def getlocalkey(file, id):
     pathhash = node.hex(hashlib.sha1(file).digest())
     return os.path.join(pathhash, id)
 
 def peersetup(ui, peer):
 
     class remotefilepeer(peer.__class__):
         @wireprotov1peer.batchable
         def x_rfl_getfile(self, file, node):
             if not self.capable('x_rfl_getfile'):
                 raise error.Abort(
                     'configured remotefile server does not support getfile')
             f = wireprotov1peer.future()
             yield {'file': file, 'node': node}, f
             code, data = f.value.split('\0', 1)
             if int(code):
                 raise error.LookupError(file, node, data)
             yield data
 
         @wireprotov1peer.batchable
         def x_rfl_getflogheads(self, path):
             if not self.capable('x_rfl_getflogheads'):
                 raise error.Abort('configured remotefile server does not '
                                   'support getflogheads')
             f = wireprotov1peer.future()
             yield {'path': path}, f
             heads = f.value.split('\n') if f.value else []
             yield heads
 
         def _updatecallstreamopts(self, command, opts):
             if command != 'getbundle':
                 return
             if (constants.NETWORK_CAP_LEGACY_SSH_GETFILES
                 not in self.capabilities()):
                 return
             if not util.safehasattr(self, '_localrepo'):
                 return
             if (constants.SHALLOWREPO_REQUIREMENT
                 not in self._localrepo.requirements):
                 return
 
             bundlecaps = opts.get('bundlecaps')
             if bundlecaps:
                 bundlecaps = [bundlecaps]
             else:
                 bundlecaps = []
 
             # shallow, includepattern, and excludepattern are a hacky way of
             # carrying over data from the local repo to this getbundle
             # command. We need to do it this way because bundle1 getbundle
             # doesn't provide any other place we can hook in to manipulate
             # getbundle args before it goes across the wire. Once we get rid
             # of bundle1, we can use bundle2's _pullbundle2extraprepare to
             # do this more cleanly.
             bundlecaps.append(constants.BUNDLE2_CAPABLITY)
             if self._localrepo.includepattern:
                 patterns = '\0'.join(self._localrepo.includepattern)
                 includecap = "includepattern=" + patterns
                 bundlecaps.append(includecap)
             if self._localrepo.excludepattern:
                 patterns = '\0'.join(self._localrepo.excludepattern)
                 excludecap = "excludepattern=" + patterns
                 bundlecaps.append(excludecap)
             opts['bundlecaps'] = ','.join(bundlecaps)
 
         def _sendrequest(self, command, args, **opts):
             self._updatecallstreamopts(command, args)
             return super(remotefilepeer, self)._sendrequest(command, args,
                                                             **opts)
 
         def _callstream(self, command, **opts):
             supertype = super(remotefilepeer, self)
             if not util.safehasattr(supertype, '_sendrequest'):
                 self._updatecallstreamopts(command, pycompat.byteskwargs(opts))
             return super(remotefilepeer, self)._callstream(command, **opts)
 
     peer.__class__ = remotefilepeer
 
 class cacheconnection(object):
     """The connection for communicating with the remote cache. Performs
     gets and sets by communicating with an external process that has the
     cache-specific implementation.
     """
     def __init__(self):
         self.pipeo = self.pipei = self.pipee = None
         self.subprocess = None
         self.connected = False
 
     def connect(self, cachecommand):
         if self.pipeo:
             raise error.Abort(_("cache connection already open"))
         self.pipei, self.pipeo, self.pipee, self.subprocess = (
             procutil.popen4(cachecommand))
         self.connected = True
 
     def close(self):
         def tryclose(pipe):
             try:
                 pipe.close()
             except Exception:
                 pass
         if self.connected:
             try:
                 self.pipei.write("exit\n")
             except Exception:
                 pass
             tryclose(self.pipei)
             self.pipei = None
             tryclose(self.pipeo)
             self.pipeo = None
             tryclose(self.pipee)
             self.pipee = None
             try:
                 # Wait for process to terminate, making sure to avoid deadlock.
                 # See https://docs.python.org/2/library/subprocess.html for
                 # warnings about wait() and deadlocking.
                 self.subprocess.communicate()
             except Exception:
                 pass
             self.subprocess = None
         self.connected = False
 
     def request(self, request, flush=True):
         if self.connected:
             try:
                 self.pipei.write(request)
                 if flush:
                     self.pipei.flush()
             except IOError:
                 self.close()
 
     def receiveline(self):
         if not self.connected:
             return None
         try:
             result = self.pipeo.readline()[:-1]
             if not result:
                 self.close()
         except IOError:
             self.close()
 
         return result
 
 def _getfilesbatch(
         remote, receivemissing, progresstick, missed, idmap, batchsize):
     # Over http(s), iterbatch is a streamy method and we can start
     # looking at results early. This means we send one (potentially
     # large) request, but then we show nice progress as we process
     # file results, rather than showing chunks of $batchsize in
     # progress.
     #
     # Over ssh, iterbatch isn't streamy because batch() wasn't
     # explicitly designed as a streaming method. In the future we
     # should probably introduce a streambatch() method upstream and
     # use that for this.
     with remote.commandexecutor() as e:
         futures = []
         for m in missed:
             futures.append(e.callcommand('x_rfl_getfile', {
                 'file': idmap[m],
                 'node': m[-40:]
             }))
 
         for i, m in enumerate(missed):
             r = futures[i].result()
             futures[i] = None  # release memory
             file_ = idmap[m]
             node = m[-40:]
             receivemissing(io.BytesIO('%d\n%s' % (len(r), r)), file_, node)
             progresstick()
 
 def _getfiles_optimistic(
     remote, receivemissing, progresstick, missed, idmap, step):
     remote._callstream("x_rfl_getfiles")
     i = 0
     pipeo = remote._pipeo
     pipei = remote._pipei
     while i < len(missed):
         # issue a batch of requests
         start = i
         end = min(len(missed), start + step)
         i = end
         for missingid in missed[start:end]:
             # issue new request
             versionid = missingid[-40:]
             file = idmap[missingid]
             sshrequest = "%s%s\n" % (versionid, file)
             pipeo.write(sshrequest)
         pipeo.flush()
 
         # receive batch results
         for missingid in missed[start:end]:
             versionid = missingid[-40:]
             file = idmap[missingid]
             receivemissing(pipei, file, versionid)
             progresstick()
 
     # End the command
     pipeo.write('\n')
     pipeo.flush()
 
 def _getfiles_threaded(
     remote, receivemissing, progresstick, missed, idmap, step):
     remote._callstream("getfiles")
     pipeo = remote._pipeo
     pipei = remote._pipei
 
     def writer():
         for missingid in missed:
             versionid = missingid[-40:]
             file = idmap[missingid]
             sshrequest = "%s%s\n" % (versionid, file)
             pipeo.write(sshrequest)
         pipeo.flush()
     writerthread = threading.Thread(target=writer)
     writerthread.daemon = True
     writerthread.start()
 
     for missingid in missed:
         versionid = missingid[-40:]
         file = idmap[missingid]
         receivemissing(pipei, file, versionid)
         progresstick()
 
     writerthread.join()
     # End the command
     pipeo.write('\n')
     pipeo.flush()
 
 class fileserverclient(object):
     """A client for requesting files from the remote file server.
     """
     def __init__(self, repo):
         ui = repo.ui
         self.repo = repo
         self.ui = ui
         self.cacheprocess = ui.config("remotefilelog", "cacheprocess")
         if self.cacheprocess:
             self.cacheprocess = util.expandpath(self.cacheprocess)
 
         # This option causes remotefilelog to pass the full file path to the
         # cacheprocess instead of a hashed key.
         self.cacheprocesspasspath = ui.configbool(
             "remotefilelog", "cacheprocess.includepath")
 
         self.debugoutput = ui.configbool("remotefilelog", "debug")
 
         self.remotecache = cacheconnection()
 
     def setstore(self, datastore, historystore, writedata, writehistory):
         self.datastore = datastore
         self.historystore = historystore
         self.writedata = writedata
         self.writehistory = writehistory
 
     def _connect(self):
         return self.repo.connectionpool.get(self.repo.fallbackpath)
 
     def request(self, fileids):
         """Takes a list of filename/node pairs and fetches them from the
         server. Files are stored in the local cache.
         A list of nodes that the server couldn't find is returned.
         If the connection fails, an exception is raised.
         """
         if not self.remotecache.connected:
             self.connect()
         cache = self.remotecache
         writedata = self.writedata
 
         repo = self.repo
         total = len(fileids)
         request = "get\n%d\n" % total
         idmap = {}
         reponame = repo.name
         for file, id in fileids:
             fullid = getcachekey(reponame, file, id)
             if self.cacheprocesspasspath:
                 request += file + '\0'
             request += fullid + "\n"
             idmap[fullid] = file
 
         cache.request(request)
 
         progress = self.ui.makeprogress(_('downloading'), total=total)
         progress.update(0)
 
         missed = []
         while True:
             missingid = cache.receiveline()
             if not missingid:
                 missedset = set(missed)
                 for missingid in idmap:
                     if not missingid in missedset:
                         missed.append(missingid)
                 self.ui.warn(_("warning: cache connection closed early - " +
                     "falling back to server\n"))
                 break
             if missingid == "0":
                 break
             if missingid.startswith("_hits_"):
                 # receive progress reports
                 parts = missingid.split("_")
                 progress.increment(int(parts[2]))
                 continue
 
             missed.append(missingid)
 
         global fetchmisses
         fetchmisses += len(missed)
 
         fromcache = total - len(missed)
         progress.update(fromcache, total=total)
         self.ui.log("remotefilelog", "remote cache hit rate is %r of %r\n",
                     fromcache, total, hit=fromcache, total=total)
 
         oldumask = os.umask(0o002)
         try:
             # receive cache misses from master
             if missed:
                 # When verbose is true, sshpeer prints 'running ssh...'
                 # to stdout, which can interfere with some command
                 # outputs
                 verbose = self.ui.verbose
                 self.ui.verbose = False
                 try:
                     with self._connect() as conn:
                         remote = conn.peer
                         if remote.capable(
                                 constants.NETWORK_CAP_LEGACY_SSH_GETFILES):
                             if not isinstance(remote, _sshv1peer):
                                 raise error.Abort('remotefilelog requires ssh '
                                                   'servers')
                             step = self.ui.configint('remotefilelog',
                                                      'getfilesstep')
                             getfilestype = self.ui.config('remotefilelog',
                                                           'getfilestype')
                             if getfilestype == 'threaded':
                                 _getfiles = _getfiles_threaded
                             else:
                                 _getfiles = _getfiles_optimistic
                             _getfiles(remote, self.receivemissing,
                                       progress.increment, missed, idmap, step)
                         elif remote.capable("x_rfl_getfile"):
                             if remote.capable('batch'):
                                 batchdefault = 100
                             else:
                                 batchdefault = 10
                             batchsize = self.ui.configint(
                                 'remotefilelog', 'batchsize', batchdefault)
                             _getfilesbatch(
                                 remote, self.receivemissing, progress.increment,
                                 missed, idmap, batchsize)
                         else:
                             raise error.Abort("configured remotefilelog server"
                                              " does not support remotefilelog")
 
                     self.ui.log("remotefilefetchlog",
                                 "Success\n",
                                 fetched_files = progress.pos - fromcache,
                                 total_to_fetch = total - fromcache)
                 except Exception:
                     self.ui.log("remotefilefetchlog",
                                 "Fail\n",
                                 fetched_files = progress.pos - fromcache,
                                 total_to_fetch = total - fromcache)
                     raise
                 finally:
                     self.ui.verbose = verbose
                 # send to memcache
                 request = "set\n%d\n%s\n" % (len(missed), "\n".join(missed))
                 cache.request(request)
 
             progress.complete()
 
             # mark ourselves as a user of this cache
             writedata.markrepo(self.repo.path)
         finally:
             os.umask(oldumask)
 
     def receivemissing(self, pipe, filename, node):
         line = pipe.readline()[:-1]
         if not line:
             raise error.ResponseError(_("error downloading file contents:"),
                                       _("connection closed early"))
         size = int(line)
         data = pipe.read(size)
         if len(data) != size:
             raise error.ResponseError(_("error downloading file contents:"),
                                       _("only received %s of %s bytes")
                                       % (len(data), size))
 
         self.writedata.addremotefilelognode(filename, bin(node),
                                              zlib.decompress(data))
 
     def connect(self):
         if self.cacheprocess:
             cmd = "%s %s" % (self.cacheprocess, self.writedata._path)
             self.remotecache.connect(cmd)
         else:
             # If no cache process is specified, we fake one that always
             # returns cache misses.  This enables tests to run easily
             # and may eventually allow us to be a drop in replacement
             # for the largefiles extension.
             class simplecache(object):
                 def __init__(self):
                     self.missingids = []
                     self.connected = True
 
                 def close(self):
                     pass
 
                 def request(self, value, flush=True):
                     lines = value.split("\n")
                     if lines[0] != "get":
                         return
                     self.missingids = lines[2:-1]
                     self.missingids.append('0')
 
                 def receiveline(self):
                     if len(self.missingids) > 0:
                         return self.missingids.pop(0)
                     return None
 
             self.remotecache = simplecache()
 
     def close(self):
         if fetches:
             msg = ("%d files fetched over %d fetches - " +
                    "(%d misses, %0.2f%% hit ratio) over %0.2fs\n") % (
                        fetched,
                        fetches,
                        fetchmisses,
                        float(fetched - fetchmisses) / float(fetched) * 100.0,
                        fetchcost)
             if self.debugoutput:
                 self.ui.warn(msg)
             self.ui.log("remotefilelog.prefetch", msg.replace("%", "%%"),
                 remotefilelogfetched=fetched,
                 remotefilelogfetches=fetches,
                 remotefilelogfetchmisses=fetchmisses,
                 remotefilelogfetchtime=fetchcost * 1000)
 
         if self.remotecache.connected:
             self.remotecache.close()
 
     def prefetch(self, fileids, force=False, fetchdata=True,
                  fetchhistory=False):
         """downloads the given file versions to the cache
         """
         repo = self.repo
         idstocheck = []
         for file, id in fileids:
             # hack
             # - we don't use .hgtags
             # - workingctx produces ids with length 42,
             #   which we skip since they aren't in any cache
             if (file == '.hgtags' or len(id) == 42
                 or not repo.shallowmatch(file)):
                 continue
 
             idstocheck.append((file, bin(id)))
 
         datastore = self.datastore
         historystore = self.historystore
         if force:
             datastore = contentstore.unioncontentstore(*repo.shareddatastores)
             historystore = metadatastore.unionmetadatastore(
                 *repo.sharedhistorystores)
 
         missingids = set()
         if fetchdata:
             missingids.update(datastore.getmissing(idstocheck))
         if fetchhistory:
             missingids.update(historystore.getmissing(idstocheck))
 
         # partition missing nodes into nullid and not-nullid so we can
         # warn about this filtering potentially shadowing bugs.
         nullids = len([None for unused, id in missingids if id == nullid])
         if nullids:
             missingids = [(f, id) for f, id in missingids if id != nullid]
             repo.ui.develwarn(
                 ('remotefilelog not fetching %d null revs'
                  ' - this is likely hiding bugs' % nullids),
                 config='remotefilelog-ext')
         if missingids:
             global fetches, fetched, fetchcost
             fetches += 1
 
             # We want to be able to detect excess individual file downloads, so
             # let's log that information for debugging.
             if fetches >= 15 and fetches < 18:
                 if fetches == 15:
                     fetchwarning = self.ui.config('remotefilelog',
                                                   'fetchwarning')
                     if fetchwarning:
                         self.ui.warn(fetchwarning + '\n')
                 self.logstacktrace()
-            missingids = [(file, hex(id)) for file, id in missingids]
+            missingids = [(file, hex(id)) for file, id in sorted(missingids)]
             fetched += len(missingids)
             start = time.time()
             missingids = self.request(missingids)
             if missingids:
                 raise error.Abort(_("unable to download %d files") %
                                   len(missingids))
             fetchcost += time.time() - start
             self._lfsprefetch(fileids)
 
     def _lfsprefetch(self, fileids):
         if not _lfsmod or not util.safehasattr(
                 self.repo.svfs, 'lfslocalblobstore'):
             return
         if not _lfsmod.wrapper.candownload(self.repo):
             return
         pointers = []
         store = self.repo.svfs.lfslocalblobstore
         for file, id in fileids:
             node = bin(id)
             rlog = self.repo.file(file)
             if rlog.flags(node) & revlog.REVIDX_EXTSTORED:
                 text = rlog.revision(node, raw=True)
                 p = _lfsmod.pointer.deserialize(text)
                 oid = p.oid()
                 if not store.has(oid):
                     pointers.append(p)
         if len(pointers) > 0:
             self.repo.svfs.lfsremoteblobstore.readbatch(pointers, store)
             assert all(store.has(p.oid()) for p in pointers)
 
     def logstacktrace(self):
         import traceback
         self.ui.log('remotefilelog', 'excess remotefilelog fetching:\n%s\n',
                     ''.join(traceback.format_stack()))