view hgext/blackbox.py @ 31793:69d8fcf20014

help: document bundle specifications

I softly formalized the concept of a "bundle specification" a while
ago when I was working on clone bundles and stream clone bundles and
wanted a more robust way to define what exactly is in a bundle file.

The concept has existed for a while. Since it is part of the clone
bundles feature and exposed to the user via the "-t" argument to
`hg bundle`, it is something we need to support for the long haul.

After the 4.1 release, I heard a few people comment that they didn't
realize you could generate zstd bundles with `hg bundle`. I'm
partially to blame for not documenting it in bundle's docstring.

Additionally, I added a hacky, experimental feature for controlling
the compression level of bundles in 76104a4899ad. As the commit
message says, I went with a quick and dirty solution out of time
constraints. Furthermore, I wanted to eventually store this
configuration in the "bundlespec" so it could be made more flexible.

Given:

a) bundlespecs are here to stay
b) we don't have great documentation over what they are, despite being
   a user-facing feature
c) the list of available compression engines and their behavior isn't
   exposed
d) we need an extensible place to modify behavior of compression
   engines

I want to move forward with formalizing bundlespecs as a user-facing
feature. This commit does that by introducing a "bundlespec" help
page. Leaning on the just-added compression engine documentation
and API, the topic also conveniently lists available compression
engines and details about them. This makes features like zstd
bundle compression more discoverable. e.g. you can now
`hg help -k zstd` and it lists the "bundlespec" topic.

# 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)))