mercurial/loggingutil.py

transaction: leave unfinished without crashing when not properly released

I think the transaction.__del__ is there just as a last resort in case
we (or an extension) forgot to release the transaction. When that
happens, the repo can (or will on Python 3?) get deleted before the
transaction. This leads to a crash in test-devel-warnings.t on Python
3 because we tried to access repo.dirstate, where repo was retried
from a weak reference. There's not much we can do here, but let's at
least avoid the crash. The user will have run `hg recover` afterwards
regardless.

Differential Revision: https://phab.mercurial-scm.org/D6664

# loggingutil.py - utility for logging events
#
# 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.

from __future__ import absolute_import

import errno

from . import (
    pycompat,
)

from .utils import (
    dateutil,
    procutil,
    stringutil,
)

def openlogfile(ui, vfs, name, maxfiles=0, maxsize=0):
    """Open log file in append mode, with optional rotation

    If maxsize > 0, the log file will be rotated up to maxfiles.
    """
    def rotate(oldpath, newpath):
        try:
            vfs.unlink(newpath)
        except OSError as err:
            if err.errno != errno.ENOENT:
                ui.debug("warning: cannot remove '%s': %s\n" %
                         (newpath, err.strerror))
        try:
            if newpath:
                vfs.rename(oldpath, newpath)
        except OSError as err:
            if err.errno != errno.ENOENT:
                ui.debug("warning: cannot rename '%s' to '%s': %s\n" %
                         (newpath, oldpath, err.strerror))

    if maxsize > 0:
        try:
            st = vfs.stat(name)
        except OSError:
            pass
        else:
            if st.st_size >= maxsize:
                path = vfs.join(name)
                for i in pycompat.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')
    return vfs(name, 'a', makeparentdirs=False)

def _formatlogline(msg):
    date = dateutil.datestr(format=b'%Y/%m/%d %H:%M:%S')
    pid = procutil.getpid()
    return b'%s (%d)> %s' % (date, pid, msg)

def _matchevent(event, tracked):
    return b'*' in tracked or event in tracked

class filelogger(object):
    """Basic logger backed by physical file with optional rotation"""

    def __init__(self, vfs, name, tracked, maxfiles=0, maxsize=0):
        self._vfs = vfs
        self._name = name
        self._trackedevents = set(tracked)
        self._maxfiles = maxfiles
        self._maxsize = maxsize

    def tracked(self, event):
        return _matchevent(event, self._trackedevents)

    def log(self, ui, event, msg, opts):
        line = _formatlogline(msg)
        try:
            with openlogfile(ui, self._vfs, self._name,
                             maxfiles=self._maxfiles,
                             maxsize=self._maxsize) as fp:
                fp.write(line)
        except IOError as err:
            ui.debug(b'cannot write to %s: %s\n'
                     % (self._name, stringutil.forcebytestr(err)))

class fileobjectlogger(object):
    """Basic logger backed by file-like object"""

    def __init__(self, fp, tracked):
        self._fp = fp
        self._trackedevents = set(tracked)

    def tracked(self, event):
        return _matchevent(event, self._trackedevents)

    def log(self, ui, event, msg, opts):
        line = _formatlogline(msg)
        try:
            self._fp.write(line)
            self._fp.flush()
        except IOError as err:
            ui.debug(b'cannot write to %s: %s\n'
                     % (stringutil.forcebytestr(self._fp.name),
                        stringutil.forcebytestr(err)))

class proxylogger(object):
    """Forward log events to another logger to be set later"""

    def __init__(self):
        self.logger = None

    def tracked(self, event):
        return self.logger is not None and self.logger.tracked(event)

    def log(self, ui, event, msg, opts):
        assert self.logger is not None
        self.logger.log(ui, event, msg, opts)