view hgext/blackbox.py @ 25561:50a6c3c55db1 stable

parsers: do not cache RevlogError type (issue4451)

Index lookups raise RevlogError when the lookup fails. The previous
implementation was caching a reference to the RevlogError type in a
static variable. This assumed that the "mercurial.error" module was
only loaded once and there was only a single copy of it floating
around in memory. Unfortunately, in some situations - including
certain mod_wsgi configurations - this was not the case: the
"mercurial.error" module could be reloaded. It was possible for a
"RevlogError" reference from the first interpreter to be used by
a second interpreter. While the underlying thing was a
"mercurial.error.RevlogError," the object IDs were different, so
the Python code in revlog.py was failing to catch the exception! This
error has existed since the C index lookup code was implemented in
changeset e8d37b78acfb, which was first released in Mercurial 2.2 in
2012.
http://emptysqua.re/blog/python-c-extensions-and-mod-wsgi/#static-variables-are-shared
contains more details.

This patch removes the caching of the RevlogError type from the
function.

Since pretty much the entire function was refactored and the return
value of the function wasn't used, I changed the function signature
to not return anything.

For reasons unknown to me, we were calling PyErr_SetObject()
with the type of RevlogError and an instance of RevlogError. This
was equivalent to the Python code "raise RevlogError(RevlogError)".
This seemed wonky and completely unnecessary. The Python code only
cares about the type of the exception, not its contents. So I got
rid of this complexity.

This is my first Python C extension patch. Please give extra scrutiny
to it during review.

# 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 = *

  [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 mercurial import util, cmdutil
from mercurial.i18n import _
import errno, os, re

cmdtable = {}
command = cmdutil.command(cmdtable)
testedwith = 'internal'
lastblackbox = None

def wrapui(ui):
    class blackboxui(ui.__class__):
        @util.propertycache
        def track(self):
            return self.configlist('blackbox', 'track', ['*'])

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

            fp = self._bbopener('blackbox.log', 'a')
            maxsize = self.configbytes('blackbox', 'maxsize', 1048576)
            if maxsize > 0:
                st = os.fstat(fp.fileno())
                if st.st_size >= maxsize:
                    path = fp.name
                    fp.close()
                    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 = self._bbopener('blackbox.log', 'a')
            return fp

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

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

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

            if blackbox:
                date = util.datestr(None, '%Y/%m/%d %H:%M:%S')
                user = util.getuser()
                formattedmsg = msg[0] % msg[1:]
                try:
                    blackbox.write('%s %s> %s' % (date, user, formattedmsg))
                except IOError, err:
                    self.debug('warning: cannot write to blackbox.log: %s\n' %
                               err.strerror)
                lastblackbox = blackbox

        def setrepo(self, repo):
            self._bbopener = repo.vfs

    ui.__class__ = 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 os.path.exists(repo.join('blackbox.log')):
        return

    limit = opts.get('limit')
    blackbox = repo.vfs('blackbox.log', 'r')
    lines = blackbox.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)))