procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
# 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)