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.
# connectionpool.py - class for pooling peer connections for reuse
#
# Copyright 2017 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 mercurial import (
hg,
sshpeer,
util,
)
_sshv1peer = sshpeer.sshv1peer
class connectionpool:
def __init__(self, repo):
self._repo = repo
self._pool = dict()
def get(self, path):
pathpool = self._pool.get(path)
if pathpool is None:
pathpool = list()
self._pool[path] = pathpool
conn = None
if len(pathpool) > 0:
try:
conn = pathpool.pop()
peer = conn.peer
# If the connection has died, drop it
if isinstance(peer, _sshv1peer):
if peer._subprocess.poll() is not None:
conn = None
except IndexError:
pass
if conn is None:
peer = hg.peer(self._repo.ui, {}, path)
if util.safehasattr(peer, '_cleanup'):
class mypeer(peer.__class__):
def _cleanup(self, warn=None):
# close pipee first so peer.cleanup reading it won't
# deadlock, if there are other processes with pipeo
# open (i.e. us).
if util.safehasattr(self, 'pipee'):
self.pipee.close()
return super(mypeer, self)._cleanup()
peer.__class__ = mypeer
conn = connection(pathpool, peer)
return conn
def close(self):
for pathpool in self._pool.values():
for conn in pathpool:
conn.close()
del pathpool[:]
class connection:
def __init__(self, pool, peer):
self._pool = pool
self.peer = peer
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
# Only add the connection back to the pool if there was no exception,
# since an exception could mean the connection is not in a reusable
# state.
if type is None:
self._pool.append(self)
else:
self.close()
def close(self):
if util.safehasattr(self.peer, 'cleanup'):
self.peer.cleanup()