Mercurial > hg
view hgext/fsmonitor/state.py @ 42743:8c9a6adec67a
rust-discovery: using the children cache in add_missing
The DAG range computation often needs to get back to very old
revisions, and turns out to be disproportionately long, given
that the end goal is to remove the descendents of the given
missing revisons from the undecided set.
The fast iteration capabilities available in the Rust case make
it possible to avoid the DAG range entirely, at the cost of
precomputing the children cache, and to simply iterate on
children of the given missing revisions.
This is a case where staying on the same side of the interface
between the two languages has clear benefits.
On discoveries with initial undecided sets
small enough to bypass sampling entirely, the total cost of
computing the children cache and the subsequent iteration
becomes better than the Python + C counterpart, which relies on
reachableroots2.
For example, on a repo with more than one million revisions with
an initial undecided set of 11 elements, we get these figures:
Rust version with simple iteration
addcommons: 57.287us
first undecided computation: 184.278334ms
first children cache computation: 131.056us
addmissings iteration: 42.766us
first addinfo total: 185.24 ms
Python + C version
first addcommons: 0.29 ms
addcommons 0.21 ms
first undecided computation 191.35 ms
addmissings 45.75 ms
first addinfo total: 237.77 ms
On discoveries with large undecided sets, the initial price paid
makes the first addinfo slower than the Python + C version,
but that's more than compensated by the gain in sampling and
subsequent iterations.
Here's an extreme example with an undecided set of a million revisions:
Rust version:
first undecided computation: 293.842629ms
first children cache computation: 407.911297ms
addmissings iteration: 34.312869ms
first addinfo total: 776.02 ms
taking initial sample
query 2: sampling time: 1318.38 ms
query 2; still undecided: 1005013, sample size is: 200
addmissings: 143.062us
Python + C version:
first undecided computation 298.13 ms
addmissings 80.13 ms
first addinfo total: 399.62 ms
taking initial sample
query 2: sampling time: 3957.23 ms
query 2; still undecided: 1005013, sample size is: 200
addmissings 52.88 ms
Differential Revision: https://phab.mercurial-scm.org/D6428
author | Georges Racinet <georges.racinet@octobus.net> |
---|---|
date | Tue, 16 Apr 2019 01:16:39 +0200 |
parents | 718f7acd6d5e |
children | 2372284d9457 |
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# state.py - fsmonitor persistent state # # Copyright 2013-2016 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 errno import os import socket import struct from mercurial.i18n import _ from mercurial import ( pathutil, util, ) _version = 4 _versionformat = ">I" class state(object): def __init__(self, repo): self._vfs = repo.vfs self._ui = repo.ui self._rootdir = pathutil.normasprefix(repo.root) self._lastclock = None self._identity = util.filestat(None) self.mode = self._ui.config('fsmonitor', 'mode') self.walk_on_invalidate = self._ui.configbool( 'fsmonitor', 'walk_on_invalidate') self.timeout = float(self._ui.config('fsmonitor', 'timeout')) def get(self): try: file = self._vfs('fsmonitor.state', 'rb') except IOError as inst: self._identity = util.filestat(None) if inst.errno != errno.ENOENT: raise return None, None, None self._identity = util.filestat.fromfp(file) versionbytes = file.read(4) if len(versionbytes) < 4: self._ui.log( 'fsmonitor', 'fsmonitor: state file only has %d bytes, ' 'nuking state\n' % len(versionbytes)) self.invalidate() return None, None, None try: diskversion = struct.unpack(_versionformat, versionbytes)[0] if diskversion != _version: # different version, nuke state and start over self._ui.log( 'fsmonitor', 'fsmonitor: version switch from %d to ' '%d, nuking state\n' % (diskversion, _version)) self.invalidate() return None, None, None state = file.read().split('\0') # state = hostname\0clock\0ignorehash\0 + list of files, each # followed by a \0 if len(state) < 3: self._ui.log( 'fsmonitor', 'fsmonitor: state file truncated (expected ' '3 chunks, found %d), nuking state\n', len(state)) self.invalidate() return None, None, None diskhostname = state[0] hostname = socket.gethostname() if diskhostname != hostname: # file got moved to a different host self._ui.log('fsmonitor', 'fsmonitor: stored hostname "%s" ' 'different from current "%s", nuking state\n' % (diskhostname, hostname)) self.invalidate() return None, None, None clock = state[1] ignorehash = state[2] # discard the value after the last \0 notefiles = state[3:-1] finally: file.close() return clock, ignorehash, notefiles def set(self, clock, ignorehash, notefiles): if clock is None: self.invalidate() return # Read the identity from the file on disk rather than from the open file # pointer below, because the latter is actually a brand new file. identity = util.filestat.frompath(self._vfs.join('fsmonitor.state')) if identity != self._identity: self._ui.debug('skip updating fsmonitor.state: identity mismatch\n') return try: file = self._vfs('fsmonitor.state', 'wb', atomictemp=True, checkambig=True) except (IOError, OSError): self._ui.warn(_("warning: unable to write out fsmonitor state\n")) return with file: file.write(struct.pack(_versionformat, _version)) file.write(socket.gethostname() + '\0') file.write(clock + '\0') file.write(ignorehash + '\0') if notefiles: file.write('\0'.join(notefiles)) file.write('\0') def invalidate(self): try: os.unlink(os.path.join(self._rootdir, '.hg', 'fsmonitor.state')) except OSError as inst: if inst.errno != errno.ENOENT: raise self._identity = util.filestat(None) def setlastclock(self, clock): self._lastclock = clock def getlastclock(self): return self._lastclock