view hgext/remotefilelog/connectionpool.py @ 51730:63ede7a43a37 stable

demandimport: don't delay threading import

A recent cpython change breaks demandimport by importing threading
locally in importlib.util.LazyLoader.exec_module; add it (plus warnings
and _weakrefset, which are imported by threading) to demandimport's
ignore list.

```
Traceback (most recent call last):
  File "/usr/bin/hg", line 57, in <module>
    from mercurial import dispatch
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "/usr/lib/python3/dist-packages/hgdemandimport/demandimportpy3.py", line 52, in exec_module
    super().exec_module(module)
  File "<frozen importlib.util>", line 257, in exec_module
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "/usr/lib/python3/dist-packages/hgdemandimport/demandimportpy3.py", line 52, in exec_module
    super().exec_module(module)
  File "<frozen importlib.util>", line 267, in exec_module
AttributeError: partially initialized module 'threading' has no attribute 'RLock' (most likely due to a circular import)
```

Ref: https://github.com/python/cpython/issues/117983
     https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1076449
     https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1076747

# 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,
)

_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 hasattr(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 hasattr(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 hasattr(self.peer, 'cleanup'):
            self.peer.cleanup()