view mercurial/loggingutil.py @ 51531:f85f23f1479b

branchcache: skip entries that are topological heads in the on disk file

In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.

So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.

# 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.


import errno

from . import (
    encoding,
)

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(
                    b"warning: cannot remove '%s': %s\n"
                    % (newpath, encoding.strtolocal(err.strerror))
                )
        try:
            if newpath:
                vfs.rename(oldpath, newpath)
        except OSError as err:
            if err.errno != errno.ENOENT:
                ui.debug(
                    b"warning: cannot rename '%s' to '%s': %s\n"
                    % (newpath, oldpath, encoding.strtolocal(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 range(maxfiles - 1, 1, -1):
                    rotate(
                        oldpath=b'%s.%d' % (path, i - 1),
                        newpath=b'%s.%d' % (path, i),
                    )
                rotate(oldpath=path, newpath=maxfiles > 0 and path + b'.1')
    return vfs(name, b'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:
    """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:
    """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:
    """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)