mercurial/loggingutil.py

py3: don't run source transformer on hgext3rd (extensions)

It's unclear why the source transformer runs on hgext3rd. It's been
like that since it was introduced in 1c22400db72d (mercurial:
implement a source transforming module loader on Python 3,
2016-07-04), and that commit didn't say anything about it (but it says
that it doesn't have "support [...] for extensions").

I find that the current handling of hgext3rd just makes it harder to
convert extensions to Python 3. It makes you convert a bunch of
strings passed to getattr() and kwargs[] to r'' that could otherwise
have been left alone. It's also really confusing that the source
transformer runs when you import the extension as "extensions.foo=",
but not as "extension.foo=/some/path".

I suppose there is small number of (very simple) extensions that would
have worked without this patch that would now be broken. It seems okay
to me to break those.

Differential Revision: https://phab.mercurial-scm.org/D6614

# 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)