view hgext/blackbox.py @ 30817:2b279126b8f5

revlog: use compression engine APIs for decompression

Now that compression engines declare their header in revlog chunks
and can decompress revlog chunks, we refactor revlog.decompress()
to use them.

Making full use of the property that revlog compressor objects are
reusable, revlog instances now maintain a dict mapping an engine's
revlog header to a compressor object. This is not only a performance
optimization for engines where compressor object reuse can result in
better performance, but it also serves as a cache of header values
so we don't need to perform redundant lookups against the compression
engine manager. (Yes, I measured and the overhead of a function call
versus a dict lookup was observed.)

Replacing the previous inline lookup table with a dict lookup was
measured to make chunk reading ~2.5% slower on changelogs and ~4.5%
slower on manifests. So, the inline lookup table has been mostly
preserved so we don't lose performance. This is unfortunate. But
many decompression operations complete in microseconds, so Python
attribute lookup, dict lookup, and function calls do matter.

The impact of this change on mozilla-unified is as follows:

$ hg perfrevlogchunks -c
! chunk
! wall 1.953663 comb 1.950000 user 1.920000 sys 0.030000 (best of 6)
! wall 1.946000 comb 1.940000 user 1.910000 sys 0.030000 (best of 6)
! chunk batch
! wall 1.791075 comb 1.800000 user 1.760000 sys 0.040000 (best of 6)
! wall 1.785690 comb 1.770000 user 1.750000 sys 0.020000 (best of 6)

$ hg perfrevlogchunks -m
! chunk
! wall 2.587262 comb 2.580000 user 2.550000 sys 0.030000 (best of 4)
! wall 2.616330 comb 2.610000 user 2.560000 sys 0.050000 (best of 4)
! chunk batch
! wall 2.427092 comb 2.420000 user 2.400000 sys 0.020000 (best of 5)
! wall 2.462061 comb 2.460000 user 2.400000 sys 0.060000 (best of 4)

Changelog chunk reading is slightly faster but manifest reading is
slower. What gives?

On this repo, 99.85% of changelog entries are zlib compressed (the 'x'
header). On the manifest, 67.5% are zlib and 32.4% are '\0'. This patch
swapped the test order of 'x' and '\0' so now 'x' is tested first. This
makes changelogs faster since they almost always hit the first branch.
This makes a significant percentage of manifest '\0' chunks slower
because that code path now performs an extra test. Yes, I too can't
believe we're able to measure the impact of an if..elif with simple
string compares. I reckon this code would benefit from being written
in C...

# blackbox.py - log repository events to a file for post-mortem debugging
#
# Copyright 2010 Nicolas Dumazet
# 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.

"""log repository events to a blackbox for debugging

Logs event information to .hg/blackbox.log to help debug and diagnose problems.
The events that get logged can be configured via the blackbox.track config key.

Examples::

  [blackbox]
  track = *
  # dirty is *EXPENSIVE* (slow);
  # each log entry indicates `+` if the repository is dirty, like :hg:`id`.
  dirty = True
  # record the source of log messages
  logsource = True

  [blackbox]
  track = command, commandfinish, commandexception, exthook, pythonhook

  [blackbox]
  track = incoming

  [blackbox]
  # limit the size of a log file
  maxsize = 1.5 MB
  # rotate up to N log files when the current one gets too big
  maxfiles = 3

"""

from __future__ import absolute_import

import errno
import re

from mercurial.i18n import _
from mercurial.node import hex

from mercurial import (
    cmdutil,
    ui as uimod,
    util,
)

cmdtable = {}
command = cmdutil.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'
lastui = None

filehandles = {}

def _openlog(vfs):
    path = vfs.join('blackbox.log')
    if path in filehandles:
        return filehandles[path]
    filehandles[path] = fp = vfs('blackbox.log', 'a')
    return fp

def _closelog(vfs):
    path = vfs.join('blackbox.log')
    fp = filehandles[path]
    del filehandles[path]
    fp.close()

def wrapui(ui):
    class blackboxui(ui.__class__):
        def __init__(self, src=None):
            super(blackboxui, self).__init__(src)
            if src is None:
                self._partialinit()
            else:
                self._bbfp = getattr(src, '_bbfp', None)
                self._bbinlog = False
                self._bbrepo = getattr(src, '_bbrepo', None)
                self._bbvfs = getattr(src, '_bbvfs', None)

        def _partialinit(self):
            if util.safehasattr(self, '_bbvfs'):
                return
            self._bbfp = None
            self._bbinlog = False
            self._bbrepo = None
            self._bbvfs = None

        def copy(self):
            self._partialinit()
            return self.__class__(self)

        @util.propertycache
        def track(self):
            return self.configlist('blackbox', 'track', ['*'])

        def _openlogfile(self):
            def rotate(oldpath, newpath):
                try:
                    self._bbvfs.unlink(newpath)
                except OSError as err:
                    if err.errno != errno.ENOENT:
                        self.debug("warning: cannot remove '%s': %s\n" %
                                   (newpath, err.strerror))
                try:
                    if newpath:
                        self._bbvfs.rename(oldpath, newpath)
                except OSError as err:
                    if err.errno != errno.ENOENT:
                        self.debug("warning: cannot rename '%s' to '%s': %s\n" %
                                   (newpath, oldpath, err.strerror))

            fp = _openlog(self._bbvfs)
            maxsize = self.configbytes('blackbox', 'maxsize', 1048576)
            if maxsize > 0:
                st = self._bbvfs.fstat(fp)
                if st.st_size >= maxsize:
                    path = fp.name
                    _closelog(self._bbvfs)
                    maxfiles = self.configint('blackbox', 'maxfiles', 7)
                    for i in xrange(maxfiles - 1, 1, -1):
                        rotate(oldpath='%s.%d' % (path, i - 1),
                               newpath='%s.%d' % (path, i))
                    rotate(oldpath=path,
                           newpath=maxfiles > 0 and path + '.1')
                    fp = _openlog(self._bbvfs)
            return fp

        def _bbwrite(self, fmt, *args):
            self._bbfp.write(fmt % args)
            self._bbfp.flush()

        def log(self, event, *msg, **opts):
            global lastui
            super(blackboxui, self).log(event, *msg, **opts)
            self._partialinit()

            if not '*' in self.track and not event in self.track:
                return

            if self._bbfp:
                ui = self
            elif self._bbvfs:
                try:
                    self._bbfp = self._openlogfile()
                except (IOError, OSError) as err:
                    self.debug('warning: cannot write to blackbox.log: %s\n' %
                               err.strerror)
                    del self._bbvfs
                    self._bbfp = None
                ui = self
            else:
                # certain ui instances exist outside the context of
                # a repo, so just default to the last blackbox that
                # was seen.
                ui = lastui

            if not ui or not ui._bbfp:
                return
            if not lastui or ui._bbrepo:
                lastui = ui
            if ui._bbinlog:
                # recursion guard
                return
            try:
                ui._bbinlog = True
                date = util.datestr(None, '%Y/%m/%d %H:%M:%S')
                user = util.getuser()
                pid = str(util.getpid())
                formattedmsg = msg[0] % msg[1:]
                rev = '(unknown)'
                changed = ''
                if ui._bbrepo:
                    ctx = ui._bbrepo[None]
                    parents = ctx.parents()
                    rev = ('+'.join([hex(p.node()) for p in parents]))
                    if (ui.configbool('blackbox', 'dirty', False) and (
                        any(ui._bbrepo.status()) or
                        any(ctx.sub(s).dirty() for s in ctx.substate)
                    )):
                        changed = '+'
                if ui.configbool('blackbox', 'logsource', False):
                    src = ' [%s]' % event
                else:
                    src = ''
                try:
                    ui._bbwrite('%s %s @%s%s (%s)%s> %s',
                        date, user, rev, changed, pid, src, formattedmsg)
                except IOError as err:
                    self.debug('warning: cannot write to blackbox.log: %s\n' %
                               err.strerror)
            finally:
                ui._bbinlog = False

        def setrepo(self, repo):
            self._bbfp = None
            self._bbinlog = False
            self._bbrepo = repo
            self._bbvfs = repo.vfs

    ui.__class__ = blackboxui
    uimod.ui = blackboxui

def uisetup(ui):
    wrapui(ui)

def reposetup(ui, repo):
    # During 'hg pull' a httppeer repo is created to represent the remote repo.
    # It doesn't have a .hg directory to put a blackbox in, so we don't do
    # the blackbox setup for it.
    if not repo.local():
        return

    if util.safehasattr(ui, 'setrepo'):
        ui.setrepo(repo)

@command('^blackbox',
    [('l', 'limit', 10, _('the number of events to show')),
    ],
    _('hg blackbox [OPTION]...'))
def blackbox(ui, repo, *revs, **opts):
    '''view the recent repository events
    '''

    if not repo.vfs.exists('blackbox.log'):
        return

    limit = opts.get('limit')
    fp = repo.vfs('blackbox.log', 'r')
    lines = fp.read().split('\n')

    count = 0
    output = []
    for line in reversed(lines):
        if count >= limit:
            break

        # count the commands by matching lines like: 2013/01/23 19:13:36 root>
        if re.match('^\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2} .*> .*', line):
            count += 1
        output.append(line)

    ui.status('\n'.join(reversed(output)))