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mitogen/mitogen/core.py

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# Copyright 2017, David Wilson
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
"""
This module implements most package functionality, but remains separate from
non-essential code in order to reduce its size, since it is also serves as the
bootstrap implementation sent to every new slave context.
"""
import collections
import encodings.latin_1
import errno
import fcntl
import itertools
import logging
import os
import signal
import socket
import struct
import sys
import threading
import time
import traceback
import warnings
import weakref
import zlib
# Python >3.7 deprecated the imp module.
warnings.filterwarnings('ignore', message='the imp module is deprecated')
import imp
# Absolute imports for <2.5.
select = __import__('select')
try:
import cPickle as pickle
except ImportError:
import pickle
try:
from cStringIO import StringIO as BytesIO
except ImportError:
from io import BytesIO
# TODO: usage of 'import' after setting __name__, but before fixing up
# sys.modules generates a warning. This happens when profiling = True.
warnings.filterwarnings('ignore',
"Parent module 'mitogen' not found while handling absolute import")
LOG = logging.getLogger('mitogen')
IOLOG = logging.getLogger('mitogen.io')
IOLOG.setLevel(logging.INFO)
LATIN1_CODEC = encodings.latin_1.Codec()
_v = False
_vv = False
GET_MODULE = 100
CALL_FUNCTION = 101
FORWARD_LOG = 102
ADD_ROUTE = 103
DEL_ROUTE = 104
ALLOCATE_ID = 105
SHUTDOWN = 106
LOAD_MODULE = 107
FORWARD_MODULE = 108
DETACHING = 109
CALL_SERVICE = 110
#: Special value used to signal disconnection or the inability to route a
#: message, when it appears in the `reply_to` field. Usually causes
#: :class:`mitogen.core.ChannelError` to be raised when it is received.
#:
#: It indicates the sender did not know how to process the message, or wishes
#: no further messages to be delivered to it. It is used when:
#:
#: * a remote receiver is disconnected or explicitly closed.
#: * a related message could not be delivered due to no route existing for it.
#: * a router is being torn down, as a sentinel value to notify
#: :meth:`mitogen.core.Router.add_handler` callbacks to clean up.
IS_DEAD = 999
try:
BaseException
except NameError:
BaseException = Exception
IS_WSL = 'Microsoft' in os.uname()[2]
PY3 = sys.version_info > (3,)
if PY3:
b = str.encode
BytesType = bytes
UnicodeType = str
FsPathTypes = (str,)
BufferType = lambda buf, start: memoryview(buf)[start:]
long = int
else:
b = str
BytesType = str
FsPathTypes = (str, unicode)
BufferType = buffer
UnicodeType = unicode
AnyTextType = (BytesType, UnicodeType)
if sys.version_info < (2, 5):
next = lambda it: it.next()
#: Default size for calls to :meth:`Side.read` or :meth:`Side.write`, and the
#: size of buffers configured by :func:`mitogen.parent.create_socketpair`. This
#: value has many performance implications, 128KiB seems to be a sweet spot.
#:
#: * When set low, large messages cause many :class:`Broker` IO loop
#: iterations, burning CPU and reducing throughput.
#: * When set high, excessive RAM is reserved by the OS for socket buffers (2x
#: per child), and an identically sized temporary userspace buffer is
#: allocated on each read that requires zeroing, and over a particular size
#: may require two system calls to allocate/deallocate.
#:
#: Care must be taken to ensure the underlying kernel object and receiving
#: program support the desired size. For example,
#:
#: * Most UNIXes have TTYs with fixed 2KiB-4KiB buffers, making them unsuitable
#: for efficient IO.
#: * Different UNIXes have varying presets for pipes, which may not be
#: configurable. On recent Linux the default pipe buffer size is 64KiB, but
#: under memory pressure may be as low as 4KiB for unprivileged processes.
#: * When communication is via an intermediary process, its internal buffers
#: effect the speed OS buffers will drain. For example OpenSSH uses 64KiB
#: reads.
#:
#: An ideal :class:`Message` has a size that is a multiple of
#: :data:`CHUNK_SIZE` inclusive of headers, to avoid wasting IO loop iterations
#: writing small trailer chunks.
CHUNK_SIZE = 131072
_tls = threading.local()
if __name__ == 'mitogen.core':
# When loaded using import mechanism, ExternalContext.main() will not have
# a chance to set the synthetic mitogen global, so just import it here.
import mitogen
else:
# When loaded as __main__, ensure classes and functions gain a __module__
# attribute consistent with the host process, so that pickling succeeds.
__name__ = 'mitogen.core'
class Error(Exception):
"""Base for all exceptions raised by Mitogen.
:param str fmt:
Exception text, or format string if `args` is non-empty.
:param tuple args:
Format string arguments.
"""
def __init__(self, fmt=None, *args):
if args:
fmt %= args
if fmt and not isinstance(fmt, UnicodeType):
fmt = fmt.decode('utf-8')
Exception.__init__(self, fmt)
class LatchError(Error):
"""Raised when an attempt is made to use a :class:`mitogen.core.Latch`
that has been marked closed."""
pass
class Blob(BytesType):
"""A serializable bytes subclass whose content is summarized in repr()
output, making it suitable for logging binary data."""
def __repr__(self):
return '[blob: %d bytes]' % len(self)
def __reduce__(self):
return (Blob, (BytesType(self),))
class Secret(UnicodeType):
"""A serializable unicode subclass whose content is masked in repr()
output, making it suitable for logging passwords."""
def __repr__(self):
return '[secret]'
if not PY3:
# TODO: what is this needed for in 2.x?
def __str__(self):
return UnicodeType(self)
def __reduce__(self):
return (Secret, (UnicodeType(self),))
class Kwargs(dict):
"""A serializable dict subclass that indicates the contained keys should be
be coerced to Unicode on Python 3 as required. Python 2 produces keyword
argument dicts whose keys are bytestrings, requiring a helper to ensure
compatibility with Python 3."""
if PY3:
def __init__(self, dct):
for k, v in dct.items():
if type(k) is bytes:
self[k.decode()] = v
else:
self[k] = v
def __repr__(self):
return 'Kwargs(%s)' % (dict.__repr__(self),)
def __reduce__(self):
return (Kwargs, (dict(self),))
class CallError(Error):
"""Serializable :class:`Error` subclass raised when
:meth:`Context.call() <mitogen.parent.Context.call>` fails. A copy of
the traceback from the external context is appended to the exception
message."""
def __init__(self, fmt=None, *args):
if not isinstance(fmt, BaseException):
Error.__init__(self, fmt, *args)
else:
e = fmt
fmt = '%s.%s: %s' % (type(e).__module__, type(e).__name__, e)
args = ()
tb = sys.exc_info()[2]
if tb:
fmt += '\n'
fmt += ''.join(traceback.format_tb(tb))
Error.__init__(self, fmt)
def __reduce__(self):
return (_unpickle_call_error, (self.args[0],))
def _unpickle_call_error(s):
if not (type(s) is UnicodeType and len(s) < 10000):
raise TypeError('cannot unpickle CallError: bad input')
inst = CallError.__new__(CallError)
Exception.__init__(inst, s)
return inst
class ChannelError(Error):
"""Raised when a channel dies or has been closed."""
remote_msg = 'Channel closed by remote end.'
local_msg = 'Channel closed by local end.'
class StreamError(Error):
"""Raised when a stream cannot be established."""
pass
class TimeoutError(Error):
"""Raised when a timeout occurs on a stream."""
pass
def to_text(o):
"""Coerce `o` to Unicode by decoding it from UTF-8 if it is an instance of
:class:`bytes`, otherwise pass it to the :class:`str` constructor. The
returned object is always a plain :class:`str`, any subclass is removed."""
if isinstance(o, BytesType):
return o.decode('utf-8')
return UnicodeType(o)
def has_parent_authority(msg, _stream=None):
"""Policy function for use with :class:`Receiver` and
:meth:`Router.add_handler` that requires incoming messages to originate
from a parent context, or on a :class:`Stream` whose :attr:`auth_id
<Stream.auth_id>` has been set to that of a parent context or the current
context."""
return (msg.auth_id == mitogen.context_id or
msg.auth_id in mitogen.parent_ids)
def listen(obj, name, func):
"""
Arrange for `func(*args, **kwargs)` to be invoked when the named signal is
fired by `obj`.
"""
signals = vars(obj).setdefault('_signals', {})
signals.setdefault(name, []).append(func)
def fire(obj, name, *args, **kwargs):
"""
Arrange for `func(*args, **kwargs)` to be invoked for every function
registered for the named signal on `obj`.
"""
signals = vars(obj).get('_signals', {})
return [func(*args, **kwargs) for func in signals.get(name, ())]
def takes_econtext(func):
func.mitogen_takes_econtext = True
return func
def takes_router(func):
func.mitogen_takes_router = True
return func
def is_blacklisted_import(importer, fullname):
"""
Return :data:`True` if `fullname` is part of a blacklisted package, or if
any packages have been whitelisted and `fullname` is not part of one.
NB:
- If a package is on both lists, then it is treated as blacklisted.
- If any package is whitelisted, then all non-whitelisted packages are
treated as blacklisted.
"""
return ((not any(fullname.startswith(s) for s in importer.whitelist)) or
(any(fullname.startswith(s) for s in importer.blacklist)))
def set_cloexec(fd):
"""Set the file descriptor `fd` to automatically close on
:func:`os.execve`. This has no effect on file descriptors inherited across
:func:`os.fork`, they must be explicitly closed through some other means,
such as :func:`mitogen.fork.on_fork`."""
flags = fcntl.fcntl(fd, fcntl.F_GETFD)
assert fd > 2
fcntl.fcntl(fd, fcntl.F_SETFD, flags | fcntl.FD_CLOEXEC)
def set_nonblock(fd):
"""Set the file descriptor `fd` to non-blocking mode. For most underlying
file types, this causes :func:`os.read` or :func:`os.write` to raise
:class:`OSError` with :data:`errno.EAGAIN` rather than block the thread
when the underlying kernel buffer is exhausted."""
flags = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK)
def set_block(fd):
"""Inverse of :func:`set_nonblock`, i.e. cause `fd` to block the thread
when the underlying kernel buffer is exhausted."""
flags = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, flags & ~os.O_NONBLOCK)
def io_op(func, *args):
"""Wrap `func(*args)` that may raise :class:`select.error`,
:class:`IOError`, or :class:`OSError`, trapping UNIX error codes relating
to disconnection and retry events in various subsystems:
* When a signal is delivered to the process on Python 2, system call retry
is signalled through :data:`errno.EINTR`. The invocation is automatically
restarted.
* When performing IO against a TTY, disconnection of the remote end is
signalled by :data:`errno.EIO`.
* When performing IO against a socket, disconnection of the remote end is
signalled by :data:`errno.ECONNRESET`.
* When performing IO against a pipe, disconnection of the remote end is
signalled by :data:`errno.EPIPE`.
:returns:
Tuple of `(return_value, disconnected)`, where `return_value` is the
return value of `func(*args)`, and `disconnected` is :data:`True` if
disconnection was detected, otherwise :data:`False`.
"""
while True:
try:
return func(*args), False
except (select.error, OSError, IOError):
e = sys.exc_info()[1]
_vv and IOLOG.debug('io_op(%r) -> OSError: %s', func, e)
if e.args[0] == errno.EINTR:
continue
if e.args[0] in (errno.EIO, errno.ECONNRESET, errno.EPIPE):
return None, True
raise
class PidfulStreamHandler(logging.StreamHandler):
"""A :class:`logging.StreamHandler` subclass used when
:meth:`Router.enable_debug() <mitogen.master.Router.enable_debug>` has been
called, or the `debug` parameter was specified during context construction.
Verifies the process ID has not changed on each call to :meth:`emit`,
reopening the associated log file when a change is detected.
This ensures logging to the per-process output files happens correctly even
when uncooperative third party components call :func:`os.fork`.
"""
#: PID that last opened the log file.
open_pid = None
#: Output path template.
template = '/tmp/mitogen.%s.%s.log'
def _reopen(self):
self.acquire()
try:
if self.open_pid == os.getpid():
return
ts = time.strftime('%Y%m%d_%H%M%S')
path = self.template % (os.getpid(), ts)
self.stream = open(path, 'w', 1)
set_cloexec(self.stream.fileno())
self.stream.write('Parent PID: %s\n' % (os.getppid(),))
self.stream.write('Created by:\n\n%s\n' % (
''.join(traceback.format_stack()),
))
self.open_pid = os.getpid()
finally:
self.release()
def emit(self, record):
if self.open_pid != os.getpid():
self._reopen()
logging.StreamHandler.emit(self, record)
def enable_debug_logging():
global _v, _vv
_v = True
_vv = True
root = logging.getLogger()
root.setLevel(logging.DEBUG)
IOLOG.setLevel(logging.DEBUG)
handler = PidfulStreamHandler()
handler.formatter = logging.Formatter(
'%(asctime)s %(levelname).1s %(name)s: %(message)s',
'%H:%M:%S'
)
root.handlers.insert(0, handler)
_profile_hook = lambda name, func, *args: func(*args)
def enable_profiling():
global _profile_hook
import cProfile
import pstats
def _profile_hook(name, func, *args):
profiler = cProfile.Profile()
profiler.enable()
try:
return func(*args)
finally:
profiler.dump_stats('/tmp/mitogen.%d.%s.pstat' % (os.getpid(), name))
profiler.create_stats()
fp = open('/tmp/mitogen.stats.%d.%s.log' % (os.getpid(), name), 'w')
try:
stats = pstats.Stats(profiler, stream=fp)
stats.sort_stats('cumulative')
stats.print_stats()
finally:
fp.close()
def import_module(modname):
"""
Import `module` and return the attribute named `attr`.
"""
return __import__(modname, None, None, [''])
if PY3:
# In 3.x Unpickler is a class exposing find_class as an overridable, but it
# cannot be overridden without subclassing.
class _Unpickler(pickle.Unpickler):
def find_class(self, module, func):
return self.find_global(module, func)
else:
# In 2.x Unpickler is a function exposing a writeable find_global
# attribute.
_Unpickler = pickle.Unpickler
class Message(object):
"""
Messages are the fundamental unit of communication, comprising fields from
the :ref:`stream-protocol` header, an optional reference to the receiving
:class:`mitogen.core.Router` for ingress messages, and helper methods for
deserialization and generating replies.
"""
#: Integer target context ID. :class:`Router` delivers messages locally
#: when their :attr:`dst_id` matches :data:`mitogen.context_id`, otherwise
#: they are routed up or downstream.
dst_id = None
#: Integer source context ID. Used as the target of replies if any are
#: generated.
src_id = None
#: Context ID under whose authority the message is acting. See
#: :ref:`source-verification`.
auth_id = None
#: Integer target handle in the destination context. This is one of the
#: :ref:`standard-handles`, or a dynamically generated handle used to
#: receive a one-time reply, such as the return value of a function call.
handle = None
#: Integer target handle to direct any reply to this message. Used to
#: receive a one-time reply, such as the return value of a function call.
#: :data:`IS_DEAD` has a special meaning when it appears in this field.
reply_to = None
#: Raw message data bytes.
data = b('')
_unpickled = object()
#: The :class:`Router` responsible for routing the message. This is
#: :data:`None` for locally originated messages.
router = None
#: The :class:`Receiver` over which the message was last received. Part of
#: the :class:`mitogen.select.Select` interface. Defaults to :data:`None`.
receiver = None
def __init__(self, **kwargs):
"""
Construct a message from from the supplied `kwargs`. :attr:`src_id` and
:attr:`auth_id` are always set to :data:`mitogen.context_id`.
"""
self.src_id = mitogen.context_id
self.auth_id = mitogen.context_id
vars(self).update(kwargs)
assert isinstance(self.data, BytesType)
def _unpickle_context(self, context_id, name):
return _unpickle_context(context_id, name, router=self.router)
def _unpickle_sender(self, context_id, dst_handle):
return _unpickle_sender(self.router, context_id, dst_handle)
def _unpickle_bytes(self, s, encoding):
s, n = LATIN1_CODEC.encode(s)
return s
def _find_global(self, module, func):
"""Return the class implementing `module_name.class_name` or raise
`StreamError` if the module is not whitelisted."""
if module == __name__:
if func == '_unpickle_call_error':
return _unpickle_call_error
elif func == '_unpickle_sender':
return self._unpickle_sender
elif func == '_unpickle_context':
return self._unpickle_context
elif func == 'Blob':
return Blob
elif func == 'Secret':
return Secret
elif func == 'Kwargs':
return Kwargs
elif module == '_codecs' and func == 'encode':
return self._unpickle_bytes
elif module == '__builtin__' and func == 'bytes':
return BytesType
raise StreamError('cannot unpickle %r/%r', module, func)
@property
def is_dead(self):
"""
:data:`True` if :attr:`reply_to` is set to the magic value
:data:`IS_DEAD`, indicating the sender considers the channel dead. Dead
messages can be raised in a variety of circumstances, see
:data:`IS_DEAD` for more information.
"""
return self.reply_to == IS_DEAD
@classmethod
def dead(cls, reason=None, **kwargs):
"""
Syntax helper to construct a dead message.
"""
kwargs['data'] = (reason or u'').encode()
return cls(reply_to=IS_DEAD, **kwargs)
@classmethod
def pickled(cls, obj, **kwargs):
"""
Construct a pickled message, setting :attr:`data` to the serialization
of `obj`, and setting remaining fields using `kwargs`.
:returns:
The new message.
"""
self = cls(**kwargs)
try:
self.data = pickle.dumps(obj, protocol=2)
except pickle.PicklingError:
e = sys.exc_info()[1]
self.data = pickle.dumps(CallError(e), protocol=2)
return self
def reply(self, msg, router=None, **kwargs):
"""
Compose a reply to this message and send it using :attr:`router`, or
`router` is :attr:`router` is :data:`None`.
:param obj:
Either a :class:`Message`, or an object to be serialized in order
to construct a new message.
:param router:
Optional router to use if :attr:`router` is :data:`None`.
:param kwargs:
Optional keyword parameters overriding message fields in the reply.
"""
if not isinstance(msg, Message):
msg = Message.pickled(msg)
msg.dst_id = self.src_id
msg.handle = self.reply_to
vars(msg).update(kwargs)
if msg.handle:
(self.router or router).route(msg)
else:
LOG.debug('Message.reply(): discarding due to zero handle: %r', msg)
if PY3:
UNPICKLER_KWARGS = {'encoding': 'bytes'}
else:
UNPICKLER_KWARGS = {}
def _throw_dead(self):
if len(self.data):
raise ChannelError(self.data.decode('utf-8', 'replace'))
elif self.src_id == mitogen.context_id:
raise ChannelError(ChannelError.local_msg)
else:
raise ChannelError(ChannelError.remote_msg)
def unpickle(self, throw=True, throw_dead=True):
"""
Unpickle :attr:`data`, optionally raising any exceptions present.
:param bool throw_dead:
If :data:`True`, raise exceptions, otherwise it is the caller's
responsibility.
:raises CallError:
The serialized data contained CallError exception.
:raises ChannelError:
The `is_dead` field was set.
"""
_vv and IOLOG.debug('%r.unpickle()', self)
if throw_dead and self.is_dead:
self._throw_dead()
obj = self._unpickled
if obj is Message._unpickled:
fp = BytesIO(self.data)
unpickler = _Unpickler(fp, **self.UNPICKLER_KWARGS)
unpickler.find_global = self._find_global
try:
# Must occur off the broker thread.
obj = unpickler.load()
self._unpickled = obj
except (TypeError, ValueError):
e = sys.exc_info()[1]
raise StreamError('invalid message: %s', e)
if throw:
if isinstance(obj, CallError):
raise obj
return obj
def __repr__(self):
return 'Message(%r, %r, %r, %r, %r, %r..%d)' % (
self.dst_id, self.src_id, self.auth_id, self.handle,
self.reply_to, (self.data or '')[:50], len(self.data)
)
class Sender(object):
"""
Senders are used to send pickled messages to a handle in another context,
it is the inverse of :class:`mitogen.core.Sender`.
Senders may be serialized, making them convenient to wire up data flows.
See :meth:`mitogen.core.Receiver.to_sender` for more information.
:param Context context:
Context to send messages to.
:param int dst_handle:
Destination handle to send messages to.
"""
def __init__(self, context, dst_handle):
self.context = context
self.dst_handle = dst_handle
def send(self, data):
"""
Send `data` to the remote end.
"""
_vv and IOLOG.debug('%r.send(%r..)', self, repr(data)[:100])
self.context.send(Message.pickled(data, handle=self.dst_handle))
explicit_close_msg = 'Sender was explicitly closed'
def close(self):
"""
Send a dead message to the remote, causing :meth:`ChannelError` to be
raised in any waiting thread.
"""
_vv and IOLOG.debug('%r.close()', self)
self.context.send(
Message.dead(
reason=self.explicit_close_msg,
handle=self.dst_handle)
)
def __repr__(self):
return 'Sender(%r, %r)' % (self.context, self.dst_handle)
def __reduce__(self):
return _unpickle_sender, (self.context.context_id, self.dst_handle)
def _unpickle_sender(router, context_id, dst_handle):
if not (isinstance(router, Router) and
isinstance(context_id, (int, long)) and context_id >= 0 and
isinstance(dst_handle, (int, long)) and dst_handle > 0):
raise TypeError('cannot unpickle Sender: bad input')
return Sender(Context(router, context_id), dst_handle)
class Receiver(object):
"""
Receivers maintain a thread-safe queue of messages sent to a handle of this
context from another context.
:param mitogen.core.Router router:
Router to register the handler on.
:param int handle:
If not :data:`None`, an explicit handle to register, otherwise an
unused handle is chosen.
:param bool persist:
If :data:`False`, unregister the handler after one message is received.
Single-message receivers are intended for RPC-like transactions, such
as in the case of :meth:`mitogen.parent.Context.call_async`.
:param mitogen.core.Context respondent:
Context this receiver is receiving from. If not :data:`None`, arranges
for the receiver to receive a dead message if messages can no longer be
routed to the context, due to disconnection or exit.
"""
#: If not :data:`None`, a reference to a function invoked as
#: `notify(receiver)` when a new message is delivered to this receiver.
#: Used by :class:`mitogen.select.Select` to implement waiting on multiple
#: receivers.
notify = None
raise_channelerror = True
def __init__(self, router, handle=None, persist=True,
respondent=None, policy=None):
self.router = router
#: The handle.
self.handle = handle # Avoid __repr__ crash in add_handler()
self._latch = Latch() # Must exist prior to .add_handler()
self.handle = router.add_handler(
fn=self._on_receive,
handle=handle,
policy=policy,
persist=persist,
respondent=respondent,
)
def __repr__(self):
return 'Receiver(%r, %r)' % (self.router, self.handle)
def to_sender(self):
"""
Return a :class:`Sender` configured to deliver messages to this
receiver. As senders are serializable, this makes it convenient to pass
`(context_id, handle)` pairs around::
def deliver_monthly_report(sender):
for line in open('monthly_report.txt'):
sender.send(line)
sender.close()
remote = router.ssh(hostname='mainframe')
recv = mitogen.core.Receiver(router)
remote.call(deliver_monthly_report, recv.to_sender())
for msg in recv:
print(msg)
"""
context = Context(self.router, mitogen.context_id)
return Sender(context, self.handle)
def _on_receive(self, msg):
"""
Callback from the Stream; appends data to the internal queue.
"""
_vv and IOLOG.debug('%r._on_receive(%r)', self, msg)
self._latch.put(msg)
if self.notify:
self.notify(self)
closed_msg = 'the Receiver has been closed'
def close(self):
"""
Unregister the receiver's handle from its associated router, and cause
:class:`ChannelError` to be raised in any thread waiting in :meth:`get`
on this receiver.
"""
if self.handle:
self.router.del_handler(self.handle)
self.handle = None
self._latch.put(Message.dead(self.closed_msg))
def empty(self):
"""
Return :data:`True` if calling :meth:`get` would block.
As with :class:`Queue.Queue`, :data:`True` may be returned even though
a subsequent call to :meth:`get` will succeed, since a message may be
posted at any moment between :meth:`empty` and :meth:`get`.
"""
return self._latch.empty()
def get(self, timeout=None, block=True, throw_dead=True):
"""
Sleep waiting for a message to arrive on this receiver.
:param float timeout:
If not :data:`None`, specifies a timeout in seconds.
:raises mitogen.core.ChannelError:
The remote end indicated the channel should be closed, or
communication with its parent context was lost.
:raises mitogen.core.TimeoutError:
Timeout was reached.
:returns:
`(msg, data)` tuple, where `msg` is the :class:`Message` that was
received, and `data` is its unpickled data part.
"""
_vv and IOLOG.debug('%r.get(timeout=%r, block=%r)', self, timeout, block)
msg = self._latch.get(timeout=timeout, block=block)
if msg.is_dead and throw_dead:
msg._throw_dead()
return msg
def __iter__(self):
"""
Yield consecutive :class:`Message` instances delivered to this receiver
until :class:`ChannelError` is raised.
"""
while True:
msg = self.get(throw_dead=False)
if msg.is_dead:
return
yield msg
class Channel(Sender, Receiver):
"""
A channel inherits from :class:`mitogen.core.Sender` and
`mitogen.core.Receiver` to provide bidirectional functionality.
Since all handles aren't known until after both ends are constructed, for
both ends to communicate through a channel, it is necessary for one end to
retrieve the handle allocated to the other and reconfigure its own channel
to match. Currently this is a manual task.
"""
def __init__(self, router, context, dst_handle, handle=None):
Sender.__init__(self, context, dst_handle)
Receiver.__init__(self, router, handle)
def __repr__(self):
return 'Channel(%s, %s)' % (
Sender.__repr__(self),
Receiver.__repr__(self)
)
class Importer(object):
"""
Import protocol implementation that fetches modules from the parent
process.
:param context: Context to communicate via.
"""
# The Mitogen package is handled specially, since the child context must
# construct it manually during startup.
MITOGEN_PKG_CONTENT = [
'compat',
'debug',
'doas',
'docker',
'kubectl',
'fakessh',
'fork',
'jail',
'lxc',
'lxd',
'master',
'minify',
'parent',
'select',
'service',
'setns',
'ssh',
'su',
'sudo',
'utils',
]
ALWAYS_BLACKLIST = [
# 2.x generates needless imports for 'builtins', while 3.x does the
# same for '__builtin__'. The correct one is built-in, the other always
# a negative round-trip.
'builtins',
'__builtin__',
# org.python.core imported by copy, pickle, xml.sax; breaks Jython, but
# very unlikely to trigger a bug report.
'org',
]
if PY3:
ALWAYS_BLACKLIST += ['cStringIO']
def __init__(self, router, context, core_src, whitelist=(), blacklist=()):
self._context = context
self._present = {'mitogen': self.MITOGEN_PKG_CONTENT}
self._lock = threading.Lock()
self.whitelist = list(whitelist) or ['']
self.blacklist = list(blacklist) + self.ALWAYS_BLACKLIST
# Presence of an entry in this map indicates in-flight GET_MODULE.
self._callbacks = {}
self._cache = {}
if core_src:
self._cache['mitogen.core'] = (
'mitogen.core',
None,
'mitogen/core.py',
zlib.compress(core_src, 9),
[],
)
self._install_handler(router)
def _install_handler(self, router):
router.add_handler(
fn=self._on_load_module,
handle=LOAD_MODULE,
policy=has_parent_authority,
)
def __repr__(self):
return 'Importer()'
def builtin_find_module(self, fullname):
# imp.find_module() will always succeed for __main__, because it is a
# built-in module. That means it exists on a special linked list deep
# within the bowels of the interpreter. We must special case it.
if fullname == '__main__':
raise ImportError()
parent, _, modname = fullname.rpartition('.')
if parent:
path = sys.modules[parent].__path__
else:
path = None
fp, pathname, description = imp.find_module(modname, path)
if fp:
fp.close()
def find_module(self, fullname, path=None):
if hasattr(_tls, 'running'):
return None
_tls.running = True
try:
_v and LOG.debug('%r.find_module(%r)', self, fullname)
pkgname, dot, _ = fullname.rpartition('.')
pkg = sys.modules.get(pkgname)
if pkgname and getattr(pkg, '__loader__', None) is not self:
LOG.debug('%r: %r is submodule of a package we did not load',
self, fullname)
return None
suffix = fullname[len(pkgname+dot):]
if pkgname and suffix not in self._present.get(pkgname, ()):
LOG.debug('%r: master doesn\'t know %r', self, fullname)
return None
# #114: explicitly whitelisted prefixes override any
# system-installed package.
if self.whitelist != ['']:
if any(fullname.startswith(s) for s in self.whitelist):
return self
try:
self.builtin_find_module(fullname)
_vv and IOLOG.debug('%r: %r is available locally',
self, fullname)
except ImportError:
_vv and IOLOG.debug('find_module(%r) returning self', fullname)
return self
finally:
del _tls.running
blacklisted_msg = (
'%r is present in the Mitogen importer blacklist, therefore this '
'context will not attempt to request it from the master, as the '
'request will always be refused.'
)
pkg_resources_msg = (
'pkg_resources is prohibited from importing __main__, as it causes '
'problems in applications whose main module is not designed to be '
're-imported by children.'
)
absent_msg = (
'The Mitogen master process was unable to serve %r. It may be a '
'native Python extension, or it may be missing entirely. Check the '
'importer debug logs on the master for more information.'
)
def _refuse_imports(self, fullname):
if is_blacklisted_import(self, fullname):
raise ImportError(self.blacklisted_msg % (fullname,))
f = sys._getframe(2)
requestee = f.f_globals['__name__']
if fullname == '__main__' and requestee == 'pkg_resources':
# Anything that imports pkg_resources will eventually cause
# pkg_resources to try and scan __main__ for its __requires__
# attribute (pkg_resources/__init__.py::_build_master()). This
# breaks any app that is not expecting its __main__ to suddenly be
# sucked over a network and injected into a remote process, like
# py.test.
raise ImportError(self.pkg_resources_msg)
if fullname == 'pbr':
# It claims to use pkg_resources to read version information, which
# would result in PEP-302 being used, but it actually does direct
# filesystem access. So instead smodge the environment to override
# any version that was defined. This will probably break something
# later.
os.environ['PBR_VERSION'] = '0.0.0'
def _on_load_module(self, msg):
if msg.is_dead:
return
tup = msg.unpickle()
fullname = tup[0]
_v and LOG.debug('Importer._on_load_module(%r)', fullname)
self._lock.acquire()
try:
self._cache[fullname] = tup
callbacks = self._callbacks.pop(fullname, [])
finally:
self._lock.release()
for callback in callbacks:
callback()
def _request_module(self, fullname, callback):
self._lock.acquire()
try:
present = fullname in self._cache
if not present:
funcs = self._callbacks.get(fullname)
if funcs is not None:
_v and LOG.debug('_request_module(%r): in flight', fullname)
funcs.append(callback)
else:
_v and LOG.debug('_request_module(%r): new request', fullname)
self._callbacks[fullname] = [callback]
self._context.send(
Message(data=b(fullname), handle=GET_MODULE)
)
finally:
self._lock.release()
if present:
callback()
def load_module(self, fullname):
fullname = to_text(fullname)
_v and LOG.debug('Importer.load_module(%r)', fullname)
self._refuse_imports(fullname)
event = threading.Event()
self._request_module(fullname, event.set)
event.wait()
ret = self._cache[fullname]
if ret[2] is None:
raise ImportError(self.absent_msg % (fullname,))
pkg_present = ret[1]
mod = sys.modules.setdefault(fullname, imp.new_module(fullname))
mod.__file__ = self.get_filename(fullname)
mod.__loader__ = self
if pkg_present is not None: # it's a package.
mod.__path__ = []
mod.__package__ = fullname
self._present[fullname] = pkg_present
else:
mod.__package__ = fullname.rpartition('.')[0] or None
if mod.__package__ and not PY3:
# 2.x requires __package__ to be exactly a string.
mod.__package__ = mod.__package__.encode()
source = self.get_source(fullname)
code = compile(source, mod.__file__, 'exec', 0, 1)
if PY3:
exec(code, vars(mod))
else:
exec('exec code in vars(mod)')
return mod
def get_filename(self, fullname):
if fullname in self._cache:
path = self._cache[fullname][2]
if path is None:
# If find_loader() returns self but a subsequent master RPC
# reveals the module can't be loaded, and so load_module()
# throws ImportError, on Python 3.x it is still possible for
# the loader to be called to fetch metadata.
raise ImportError(self.absent_msg % (fullname,))
return u'master:' + self._cache[fullname][2]
def get_source(self, fullname):
if fullname in self._cache:
compressed = self._cache[fullname][3]
if compressed is None:
raise ImportError(self.absent_msg % (fullname,))
source = zlib.decompress(self._cache[fullname][3])
if PY3:
return to_text(source)
return source
class LogHandler(logging.Handler):
def __init__(self, context):
logging.Handler.__init__(self)
self.context = context
self.local = threading.local()
self._buffer = []
def uncork(self):
self._send = self.context.send
for msg in self._buffer:
self._send(msg)
self._buffer = None
def _send(self, msg):
self._buffer.append(msg)
def emit(self, rec):
if rec.name == 'mitogen.io' or \
getattr(self.local, 'in_emit', False):
return
self.local.in_emit = True
try:
msg = self.format(rec)
encoded = '%s\x00%s\x00%s' % (rec.name, rec.levelno, msg)
if isinstance(encoded, UnicodeType):
# Logging package emits both :(
encoded = encoded.encode('utf-8')
self._send(Message(data=encoded, handle=FORWARD_LOG))
finally:
self.local.in_emit = False
class Side(object):
"""
Represent a single side of a :class:`BasicStream`. This exists to allow
streams implemented using unidirectional (e.g. UNIX pipe) and bidirectional
(e.g. UNIX socket) file descriptors to operate identically.
:param mitogen.core.Stream stream:
The stream this side is associated with.
:param int fd:
Underlying file descriptor.
:param bool keep_alive:
Value for :attr:`keep_alive`
During construction, the file descriptor has its :data:`os.O_NONBLOCK` flag
enabled using :func:`fcntl.fcntl`.
"""
_fork_refs = weakref.WeakValueDictionary()
def __init__(self, stream, fd, cloexec=True, keep_alive=True, blocking=False):
#: The :class:`Stream` for which this is a read or write side.
self.stream = stream
#: Integer file descriptor to perform IO on, or :data:`None` if
#: :meth:`close` has been called.
self.fd = fd
self.closed = False
#: If :data:`True`, causes presence of this side in
#: :class:`Broker`'s active reader set to defer shutdown until the
#: side is disconnected.
self.keep_alive = keep_alive
self._fork_refs[id(self)] = self
if cloexec:
set_cloexec(fd)
if not blocking:
set_nonblock(fd)
def __repr__(self):
return '<Side of %r fd %s>' % (self.stream, self.fd)
@classmethod
def _on_fork(cls):
for side in list(cls._fork_refs.values()):
side.close()
def close(self):
"""
Call :func:`os.close` on :attr:`fd` if it is not :data:`None`,
then set it to :data:`None`.
"""
if not self.closed:
_vv and IOLOG.debug('%r.close()', self)
self.closed = True
os.close(self.fd)
def read(self, n=CHUNK_SIZE):
"""
Read up to `n` bytes from the file descriptor, wrapping the underlying
:func:`os.read` call with :func:`io_op` to trap common disconnection
conditions.
:meth:`read` always behaves as if it is reading from a regular UNIX
file; socket, pipe, and TTY disconnection errors are masked and result
in a 0-sized read like a regular file.
:returns:
Bytes read, or the empty to string to indicate disconnection was
detected.
"""
if self.closed:
# Refuse to touch the handle after closed, it may have been reused
# by another thread. TODO: synchronize read()/write()/close().
return b('')
s, disconnected = io_op(os.read, self.fd, n)
if disconnected:
return b('')
return s
def write(self, s):
"""
Write as much of the bytes from `s` as possible to the file descriptor,
wrapping the underlying :func:`os.write` call with :func:`io_op` to
trap common disconnection connditions.
:returns:
Number of bytes written, or :data:`None` if disconnection was
detected.
"""
if self.closed or self.fd is None:
# Refuse to touch the handle after closed, it may have been reused
# by another thread.
return None
written, disconnected = io_op(os.write, self.fd, s)
if disconnected:
return None
return written
class BasicStream(object):
#: A :class:`Side` representing the stream's receive file descriptor.
receive_side = None
#: A :class:`Side` representing the stream's transmit file descriptor.
transmit_side = None
def on_receive(self, broker):
"""
Called by :class:`Broker` when the stream's :attr:`receive_side` has
been marked readable using :meth:`Broker.start_receive` and the broker
has detected the associated file descriptor is ready for reading.
Subclasses must implement this if :meth:`Broker.start_receive` is ever
called on them, and the method must call :meth:`on_disconect` if
reading produces an empty string.
"""
pass
def on_transmit(self, broker):
"""
Called by :class:`Broker` when the stream's :attr:`transmit_side`
has been marked writeable using :meth:`Broker._start_transmit` and
the broker has detected the associated file descriptor is ready for
writing.
Subclasses must implement this if :meth:`Broker._start_transmit` is
ever called on them.
"""
pass
def on_shutdown(self, broker):
"""
Called by :meth:`Broker.shutdown` to allow the stream time to
gracefully shutdown. The base implementation simply called
:meth:`on_disconnect`.
"""
_v and LOG.debug('%r.on_shutdown()', self)
fire(self, 'shutdown')
self.on_disconnect(broker)
def on_disconnect(self, broker):
"""
Called by :class:`Broker` to force disconnect the stream. The base
implementation simply closes :attr:`receive_side` and
:attr:`transmit_side` and unregisters the stream from the broker.
"""
LOG.debug('%r.on_disconnect()', self)
if self.receive_side:
broker.stop_receive(self)
self.receive_side.close()
if self.transmit_side:
broker._stop_transmit(self)
self.transmit_side.close()
fire(self, 'disconnect')
class Stream(BasicStream):
"""
:class:`BasicStream` subclass implementing mitogen's :ref:`stream
protocol <stream-protocol>`.
"""
#: If not :data:`None`, :class:`Router` stamps this into
#: :attr:`Message.auth_id` of every message received on this stream.
auth_id = None
#: If not :data:`False`, indicates the stream has :attr:`auth_id` set and
#: its value is the same as :data:`mitogen.context_id` or appears in
#: :data:`mitogen.parent_ids`.
is_privileged = False
def __init__(self, router, remote_id, **kwargs):
self._router = router
self.remote_id = remote_id
self.name = u'default'
self.sent_modules = set(['mitogen', 'mitogen.core'])
self.construct(**kwargs)
self._input_buf = collections.deque()
self._output_buf = collections.deque()
self._input_buf_len = 0
self._output_buf_len = 0
#: Routing records the dst_id of every message arriving from this
#: stream. Any arriving DEL_ROUTE is rebroadcast for any such ID.
self.egress_ids = set()
def construct(self):
pass
def _internal_receive(self, broker, buf):
if self._input_buf and self._input_buf_len < 128:
self._input_buf[0] += buf
else:
self._input_buf.append(buf)
self._input_buf_len += len(buf)
while self._receive_one(broker):
pass
def on_receive(self, broker):
"""Handle the next complete message on the stream. Raise
:class:`StreamError` on failure."""
_vv and IOLOG.debug('%r.on_receive()', self)
buf = self.receive_side.read()
if not buf:
return self.on_disconnect(broker)
self._internal_receive(broker, buf)
HEADER_FMT = '>hLLLLLL'
HEADER_LEN = struct.calcsize(HEADER_FMT)
HEADER_MAGIC = 0x4d49 # 'MI'
corrupt_msg = (
'Corruption detected: frame signature incorrect. This likely means '
'some external process is interfering with the connection. Received:'
'\n\n'
'%r'
)
def _receive_one(self, broker):
if self._input_buf_len < self.HEADER_LEN:
return False
msg = Message()
msg.router = self._router
(magic, msg.dst_id, msg.src_id, msg.auth_id,
msg.handle, msg.reply_to, msg_len) = struct.unpack(
self.HEADER_FMT,
self._input_buf[0][:self.HEADER_LEN],
)
if magic != self.HEADER_MAGIC:
LOG.error(self.corrupt_msg, self._input_buf[0][:128])
self.on_disconnect(broker)
return False
if msg_len > self._router.max_message_size:
LOG.error('Maximum message size exceeded (got %d, max %d)',
msg_len, self._router.max_message_size)
self.on_disconnect(broker)
return False
total_len = msg_len + self.HEADER_LEN
if self._input_buf_len < total_len:
_vv and IOLOG.debug(
'%r: Input too short (want %d, got %d)',
self, msg_len, self._input_buf_len - self.HEADER_LEN
)
return False
start = self.HEADER_LEN
prev_start = start
remain = total_len
bits = []
while remain:
buf = self._input_buf.popleft()
bit = buf[start:remain]
bits.append(bit)
remain -= len(bit) + start
prev_start = start
start = 0
msg.data = b('').join(bits)
self._input_buf.appendleft(buf[prev_start+len(bit):])
self._input_buf_len -= total_len
self._router._async_route(msg, self)
return True
def pending_bytes(self):
"""
Return the number of bytes queued for transmission on this stream. This
can be used to limit the amount of data buffered in RAM by an otherwise
unlimited consumer.
For an accurate result, this method should be called from the Broker
thread, for example by using :meth:`Broker.defer_sync`.
"""
return self._output_buf_len
def on_transmit(self, broker):
"""Transmit buffered messages."""
_vv and IOLOG.debug('%r.on_transmit()', self)
if self._output_buf:
buf = self._output_buf.popleft()
written = self.transmit_side.write(buf)
if not written:
_v and LOG.debug('%r.on_transmit(): disconnection detected', self)
self.on_disconnect(broker)
return
elif written != len(buf):
self._output_buf.appendleft(BufferType(buf, written))
_vv and IOLOG.debug('%r.on_transmit() -> len %d', self, written)
self._output_buf_len -= written
if not self._output_buf:
broker._stop_transmit(self)
def _send(self, msg):
_vv and IOLOG.debug('%r._send(%r)', self, msg)
pkt = struct.pack(self.HEADER_FMT, self.HEADER_MAGIC, msg.dst_id,
msg.src_id, msg.auth_id, msg.handle,
msg.reply_to or 0, len(msg.data)) + msg.data
if not self._output_buf_len:
self._router.broker._start_transmit(self)
self._output_buf.append(pkt)
self._output_buf_len += len(pkt)
def send(self, msg):
"""Send `data` to `handle`, and tell the broker we have output. May
be called from any thread."""
self._router.broker.defer(self._send, msg)
def on_shutdown(self, broker):
"""Override BasicStream behaviour of immediately disconnecting."""
_v and LOG.debug('%r.on_shutdown(%r)', self, broker)
def accept(self, rfd, wfd):
# TODO: what is this os.dup for?
self.receive_side = Side(self, os.dup(rfd))
self.transmit_side = Side(self, os.dup(wfd))
def __repr__(self):
cls = type(self)
return '%s.%s(%r)' % (cls.__module__, cls.__name__, self.name)
class Context(object):
"""
Represent a remote context regardless of the underlying connection method.
Context objects are simple facades that emit messages through an
associated router, and have :ref:`signals` raised against them in response
to various events relating to the context.
**Note:** This is the somewhat limited core version, used by child
contexts. The master subclass is documented below this one.
Contexts maintain no internal state and are thread-safe.
Prefer :meth:`Router.context_by_id` over constructing context objects
explicitly, as that method is deduplicating, and returns the only context
instance :ref:`signals` will be raised on.
:param Router router:
Router to emit messages through.
:param int context_id:
Context ID.
:param str name:
Context name.
"""
remote_name = None
def __init__(self, router, context_id, name=None):
self.router = router
self.context_id = context_id
self.name = name
def __reduce__(self):
name = self.name
if name and not isinstance(name, UnicodeType):
name = UnicodeType(name, 'utf-8')
return _unpickle_context, (self.context_id, name)
def on_disconnect(self):
_v and LOG.debug('%r.on_disconnect()', self)
fire(self, 'disconnect')
def send_async(self, msg, persist=False):
"""
Arrange for `msg` to be delivered to this context, with replies
directed to a newly constructed receiver. :attr:`dst_id
<Message.dst_id>` is set to the target context ID, and :attr:`reply_to
<Message.reply_to>` is set to the newly constructed receiver's handle.
:param bool persist:
If :data:`False`, the handler will be unregistered after a single
message has been received.
:param mitogen.core.Message msg:
The message.
:returns:
:class:`Receiver` configured to receive any replies sent to the
message's `reply_to` handle.
"""
if self.router.broker._thread == threading.currentThread(): # TODO
raise SystemError('Cannot making blocking call on broker thread')
receiver = Receiver(self.router, persist=persist, respondent=self)
msg.dst_id = self.context_id
msg.reply_to = receiver.handle
_v and LOG.debug('%r.send_async(%r)', self, msg)
self.send(msg)
return receiver
def call_service_async(self, service_name, method_name, **kwargs):
_v and LOG.debug('%r.call_service_async(%r, %r, %r)',
self, service_name, method_name, kwargs)
if isinstance(service_name, BytesType):
service_name = service_name.encode('utf-8')
elif not isinstance(service_name, UnicodeType):
service_name = service_name.name() # Service.name()
tup = (service_name, to_text(method_name), Kwargs(kwargs))
msg = Message.pickled(tup, handle=CALL_SERVICE)
return self.send_async(msg)
def send(self, msg):
"""
Arrange for `msg` to be delivered to this context. :attr:`dst_id
<Message.dst_id>` is set to the target context ID.
:param Message msg:
Message.
"""
msg.dst_id = self.context_id
self.router.route(msg)
def call_service(self, service_name, method_name, **kwargs):
recv = self.call_service_async(service_name, method_name, **kwargs)
return recv.get().unpickle()
def send_await(self, msg, deadline=None):
"""
Like :meth:`send_async`, but expect a single reply (`persist=False`)
delivered within `deadline` seconds.
:param mitogen.core.Message msg:
The message.
:param float deadline:
If not :data:`None`, seconds before timing out waiting for a reply.
:returns:
Deserialized reply.
:raises TimeoutError:
No message was received and `deadline` passed.
"""
receiver = self.send_async(msg)
response = receiver.get(deadline)
data = response.unpickle()
_vv and IOLOG.debug('%r._send_await() -> %r', self, data)
return data
def __repr__(self):
return 'Context(%s, %r)' % (self.context_id, self.name)
def _unpickle_context(context_id, name, router=None):
if not (isinstance(context_id, (int, long)) and context_id >= 0 and (
(name is None) or
(isinstance(name, UnicodeType) and len(name) < 100))
):
raise TypeError('cannot unpickle Context: bad input')
if isinstance(router, Router):
return router.context_by_id(context_id, name=name)
return Context(None, context_id, name) # For plain Jane pickle.
class Poller(object):
"""
A poller manages OS file descriptors the user is waiting to become
available for IO. The :meth:`poll` method blocks the calling thread
until one or more become ready. The default implementation is based on
:func:`select.select`.
Each descriptor has an associated `data` element, which is unique for each
readiness type, and defaults to being the same as the file descriptor. The
:meth:`poll` method yields the data associated with a descriptor, rather
than the descriptor itself, allowing concise loops like::
p = Poller()
p.start_receive(conn.fd, data=conn.on_read)
p.start_transmit(conn.fd, data=conn.on_write)
for callback in p.poll():
callback() # invoke appropriate bound instance method
Pollers may be modified while :meth:`poll` is yielding results. Removals
are processed immediately, causing pendings event for the descriptor to be
discarded.
The :meth:`close` method must be called when a poller is discarded to avoid
a resource leak.
Pollers may only be used by one thread at a time.
"""
#: Increments on every poll(). Used to version _rfds and _wfds.
_generation = 1
def __init__(self):
self._rfds = {}
self._wfds = {}
def __repr__(self):
return '%s(%#x)' % (type(self).__name__, id(self))
@property
def readers(self):
"""
Return a list of `(fd, data)` tuples for every FD registered for
receive readiness.
"""
return list((fd, data) for fd, (data, gen) in self._rfds.items())
@property
def writers(self):
"""
Return a list of `(fd, data)` tuples for every FD registered for
transmit readiness.
"""
return list((fd, data) for fd, (data, gen) in self._wfds.items())
def close(self):
"""
Close any underlying OS resource used by the poller.
"""
pass
def start_receive(self, fd, data=None):
"""
Cause :meth:`poll` to yield `data` when `fd` is readable.
"""
self._rfds[fd] = (data or fd, self._generation)
def stop_receive(self, fd):
"""
Stop yielding readability events for `fd`.
Redundant calls to :meth:`stop_receive` are silently ignored, this may
change in future.
"""
self._rfds.pop(fd, None)
def start_transmit(self, fd, data=None):
"""
Cause :meth:`poll` to yield `data` when `fd` is writeable.
"""
self._wfds[fd] = (data or fd, self._generation)
def stop_transmit(self, fd):
"""
Stop yielding writeability events for `fd`.
Redundant calls to :meth:`stop_transmit` are silently ignored, this may
change in future.
"""
self._wfds.pop(fd, None)
def _poll(self, timeout):
(rfds, wfds, _), _ = io_op(select.select,
self._rfds,
self._wfds,
(), timeout
)
for fd in rfds:
_vv and IOLOG.debug('%r: POLLIN for %r', self, fd)
data, gen = self._rfds.get(fd, (None, None))
if gen and gen < self._generation:
yield data
for fd in wfds:
_vv and IOLOG.debug('%r: POLLOUT for %r', self, fd)
data, gen = self._wfds.get(fd, (None, None))
if gen and gen < self._generation:
yield data
def poll(self, timeout=None):
"""
Block the calling thread until one or more FDs are ready for IO.
:param float timeout:
If not :data:`None`, seconds to wait without an event before
returning an empty iterable.
:returns:
Iterable of `data` elements associated with ready FDs.
"""
_vv and IOLOG.debug('%r.poll(%r)', self, timeout)
self._generation += 1
return self._poll(timeout)
class Latch(object):
"""
A latch is a :class:`Queue.Queue`-like object that supports mutation and
waiting from multiple threads, however unlike :class:`Queue.Queue`,
waiting threads always remain interruptible, so CTRL+C always succeeds, and
waits where a timeout is set experience no wake up latency. These
properties are not possible in combination using the built-in threading
primitives available in Python 2.x.
Latches implement queues using the UNIX self-pipe trick, and a per-thread
:func:`socket.socketpair` that is lazily created the first time any
latch attempts to sleep on a thread, and dynamically associated with the
waiting Latch only for duration of the wait.
See :ref:`waking-sleeping-threads` for further discussion.
"""
poller_class = Poller
# The _cls_ prefixes here are to make it crystal clear in the code which
# state mutation isn't covered by :attr:`_lock`.
#: List of reusable :func:`socket.socketpair` tuples. The list is from
#: multiple threads, the only safe operations are `append()` and `pop()`.
_cls_idle_socketpairs = []
#: List of every socket object that must be closed by :meth:`_on_fork`.
#: Inherited descriptors cannot be reused, as the duplicated handles
#: reference the same underlying kernel-side sockets still in use by
#: the parent process.
_cls_all_sockets = []
def __init__(self):
self.closed = False
self._lock = threading.Lock()
#: List of unconsumed enqueued items.
self._queue = []
#: List of `(wsock, cookie)` awaiting an element, where `wsock` is the
#: socketpair's write side, and `cookie` is the string to write.
self._sleeping = []
#: Number of elements of :attr:`_sleeping` that have already been
#: woken, and have a corresponding element index from :attr:`_queue`
#: assigned to them.
self._waking = 0
@classmethod
def _on_fork(cls):
"""
Clean up any files belonging to the parent process after a fork.
"""
cls._cls_idle_socketpairs = []
while cls._cls_all_sockets:
cls._cls_all_sockets.pop().close()
def close(self):
"""
Mark the latch as closed, and cause every sleeping thread to be woken,
with :class:`mitogen.core.LatchError` raised in each thread.
"""
self._lock.acquire()
try:
self.closed = True
while self._waking < len(self._sleeping):
wsock, cookie = self._sleeping[self._waking]
self._wake(wsock, cookie)
self._waking += 1
finally:
self._lock.release()
def empty(self):
"""
Return :data:`True` if calling :meth:`get` would block.
As with :class:`Queue.Queue`, :data:`True` may be returned even
though a subsequent call to :meth:`get` will succeed, since a
message may be posted at any moment between :meth:`empty` and
:meth:`get`.
As with :class:`Queue.Queue`, :data:`False` may be returned even
though a subsequent call to :meth:`get` will block, since another
waiting thread may be woken at any moment between :meth:`empty` and
:meth:`get`.
"""
return len(self._queue) == 0
def _get_socketpair(self):
"""
Return an unused socketpair, creating one if none exist.
"""
try:
return self._cls_idle_socketpairs.pop() # pop() must be atomic
except IndexError:
rsock, wsock = socket.socketpair()
set_cloexec(rsock.fileno())
set_cloexec(wsock.fileno())
self._cls_all_sockets.extend((rsock, wsock))
return rsock, wsock
def _make_cookie(self):
"""
Return a string encoding the ID of the instance and the current thread.
This disambiguates legitimate wake-ups, accidental writes to the FD,
and buggy internal FD sharing.
"""
ident = threading.currentThread().ident
return b(u'%010d-%016x-%016x' % (os.getpid(), int(id(self)), ident))
COOKIE_SIZE = len(_make_cookie(None))
def get(self, timeout=None, block=True):
"""
Return the next enqueued object, or sleep waiting for one.
:param float timeout:
If not :data:`None`, specifies a timeout in seconds.
:param bool block:
If :data:`False`, immediately raise
:class:`mitogen.core.TimeoutError` if the latch is empty.
:raises mitogen.core.LatchError:
:meth:`close` has been called, and the object is no longer valid.
:raises mitogen.core.TimeoutError:
Timeout was reached.
:returns:
The de-queued object.
"""
_vv and IOLOG.debug('%r.get(timeout=%r, block=%r)',
self, timeout, block)
self._lock.acquire()
try:
if self.closed:
raise LatchError()
i = len(self._sleeping)
if len(self._queue) > i:
_vv and IOLOG.debug('%r.get() -> %r', self, self._queue[i])
return self._queue.pop(i)
if not block:
raise TimeoutError()
rsock, wsock = self._get_socketpair()
cookie = self._make_cookie()
self._sleeping.append((wsock, cookie))
finally:
self._lock.release()
poller = self.poller_class()
poller.start_receive(rsock.fileno())
try:
return self._get_sleep(poller, timeout, block, rsock, wsock, cookie)
finally:
poller.close()
def _get_sleep(self, poller, timeout, block, rsock, wsock, cookie):
"""
When a result is not immediately available, sleep waiting for
:meth:`put` to write a byte to our socket pair.
"""
_vv and IOLOG.debug(
'%r._get_sleep(timeout=%r, block=%r, rfd=%d, wfd=%d)',
self, timeout, block, rsock.fileno(), wsock.fileno()
)
e = None
woken = None
try:
woken = list(poller.poll(timeout))
except Exception:
e = sys.exc_info()[1]
self._lock.acquire()
try:
i = self._sleeping.index((wsock, cookie))
del self._sleeping[i]
if not woken:
raise e or TimeoutError()
got_cookie = rsock.recv(self.COOKIE_SIZE)
self._cls_idle_socketpairs.append((rsock, wsock))
assert cookie == got_cookie, (
"Cookie incorrect; got %r, expected %r" \
% (got_cookie, cookie)
)
assert i < self._waking, (
"Cookie correct, but no queue element assigned."
)
self._waking -= 1
if self.closed:
raise LatchError()
_vv and IOLOG.debug('%r.get() wake -> %r', self, self._queue[i])
return self._queue.pop(i)
finally:
self._lock.release()
def put(self, obj):
"""
Enqueue an object, waking the first thread waiting for a result, if one
exists.
:raises mitogen.core.LatchError:
:meth:`close` has been called, and the object is no longer valid.
"""
_vv and IOLOG.debug('%r.put(%r)', self, obj)
self._lock.acquire()
try:
if self.closed:
raise LatchError()
self._queue.append(obj)
if self._waking < len(self._sleeping):
wsock, cookie = self._sleeping[self._waking]
self._waking += 1
_vv and IOLOG.debug('%r.put() -> waking wfd=%r',
self, wsock.fileno())
self._wake(wsock, cookie)
finally:
self._lock.release()
def _wake(self, wsock, cookie):
try:
os.write(wsock.fileno(), cookie)
except OSError:
e = sys.exc_info()[1]
if e.args[0] != errno.EBADF:
raise
def __repr__(self):
return 'Latch(%#x, size=%d, t=%r)' % (
id(self),
len(self._queue),
threading.currentThread().name,
)
class Waker(BasicStream):
"""
:class:`BasicStream` subclass implementing the `UNIX self-pipe trick`_.
Used to wake the multiplexer when another thread needs to modify its state
(via a cross-thread function call).
.. _UNIX self-pipe trick: https://cr.yp.to/docs/selfpipe.html
"""
broker_ident = None
def __init__(self, broker):
self._broker = broker
self._lock = threading.Lock()
self._deferred = []
rfd, wfd = os.pipe()
self.receive_side = Side(self, rfd)
self.transmit_side = Side(self, wfd)
def __repr__(self):
return 'Waker(%r rfd=%r, wfd=%r)' % (
self._broker,
self.receive_side and self.receive_side.fd,
self.transmit_side and self.transmit_side.fd,
)
@property
def keep_alive(self):
"""
Prevent immediate Broker shutdown while deferred functions remain.
"""
self._lock.acquire()
try:
return len(self._deferred)
finally:
self._lock.release()
def on_receive(self, broker):
"""
Drain the pipe and fire callbacks. Since :attr:`_deferred` is
synchronized, :meth:`defer` and :meth:`on_receive` can conspire to
ensure only one byte needs to be pending regardless of queue length.
"""
_vv and IOLOG.debug('%r.on_receive()', self)
self._lock.acquire()
try:
self.receive_side.read(1)
deferred = self._deferred
self._deferred = []
finally:
self._lock.release()
for func, args, kwargs in deferred:
try:
func(*args, **kwargs)
except Exception:
LOG.exception('defer() crashed: %r(*%r, **%r)',
func, args, kwargs)
self._broker.shutdown()
def _wake(self):
"""
Wake the multiplexer by writing a byte. If Broker is midway through
teardown, the FD may already be closed, so ignore EBADF.
"""
try:
self.transmit_side.write(b(' '))
except OSError:
e = sys.exc_info()[1]
if e.args[0] != errno.EBADF:
raise
broker_shutdown_msg = (
"An attempt was made to enqueue a message with a Broker that has "
"already begun shutting down. It is likely your program called "
"Broker.shutdown() too early."
)
def defer(self, func, *args, **kwargs):
"""
Arrange for `func()` to execute on the broker thread. This function
returns immediately without waiting the result of `func()`. Use
:meth:`defer_sync` to block until a result is available.
:raises mitogen.core.Error:
:meth:`defer` was called after :class:`Broker` has begun shutdown.
"""
if threading.currentThread().ident == self.broker_ident:
_vv and IOLOG.debug('%r.defer() [immediate]', self)
return func(*args, **kwargs)
if not self._broker._alive:
raise Error(self.broker_shutdown_msg)
_vv and IOLOG.debug('%r.defer() [fd=%r]', self, self.transmit_side.fd)
self._lock.acquire()
try:
if not self._deferred:
self._wake()
self._deferred.append((func, args, kwargs))
finally:
self._lock.release()
class IoLogger(BasicStream):
"""
:class:`BasicStream` subclass that sets up redirection of a standard
UNIX file descriptor back into the Python :mod:`logging` package.
"""
_buf = ''
def __init__(self, broker, name, dest_fd):
self._broker = broker
self._name = name
self._rsock, self._wsock = socket.socketpair()
os.dup2(self._wsock.fileno(), dest_fd)
set_cloexec(self._wsock.fileno())
self._log = logging.getLogger(name)
# #453: prevent accidental log initialization in a child creating a
# feedback loop.
self._log.propagate = False
self._log.handlers = logging.getLogger().handlers[:]
self.receive_side = Side(self, self._rsock.fileno())
self.transmit_side = Side(self, dest_fd, cloexec=False, blocking=True)
self._broker.start_receive(self)
def __repr__(self):
return '<IoLogger %s>' % (self._name,)
def _log_lines(self):
while self._buf.find('\n') != -1:
line, _, self._buf = self._buf.partition('\n')
self._log.info('%s', line.rstrip('\n'))
def on_shutdown(self, broker):
"""Shut down the write end of the logging socket."""
_v and LOG.debug('%r.on_shutdown()', self)
if not IS_WSL:
# #333: WSL generates invalid readiness indication on shutdown()
self._wsock.shutdown(socket.SHUT_WR)
self._wsock.close()
self.transmit_side.close()
def on_receive(self, broker):
_vv and IOLOG.debug('%r.on_receive()', self)
buf = self.receive_side.read()
if not buf:
return self.on_disconnect(broker)
self._buf += buf.decode('latin1')
self._log_lines()
class Router(object):
"""
Route messages between contexts, and invoke local handlers for messages
addressed to this context. :meth:`Router.route() <route>` straddles the
:class:`Broker` thread and user threads, it is safe to call anywhere.
**Note:** This is the somewhat limited core version of the Router class
used by child contexts. The master subclass is documented below this one.
"""
context_class = Context
max_message_size = 128 * 1048576
#: When :data:`True`, permit children to only communicate with the current
#: context or a parent of the current context. Routing between siblings or
#: children of parents is prohibited, ensuring no communication is possible
#: between intentionally partitioned networks, such as when a program
#: simultaneously manipulates hosts spread across a corporate and a
#: production network, or production networks that are otherwise
#: air-gapped.
#:
#: Sending a prohibited message causes an error to be logged and a dead
#: message to be sent in reply to the errant message, if that message has
#: ``reply_to`` set.
#:
#: The value of :data:`unidirectional` becomes the default for the
#: :meth:`local() <mitogen.master.Router.local>` `unidirectional`
#: parameter.
unidirectional = False
def __init__(self, broker):
self.broker = broker
listen(broker, 'exit', self._on_broker_exit)
# Here seems as good a place as any.
global _v, _vv
_v = logging.getLogger().level <= logging.DEBUG
_vv = IOLOG.level <= logging.DEBUG
#: context ID -> Stream
self._stream_by_id = {}
#: List of contexts to notify of shutdown.
self._context_by_id = {}
self._last_handle = itertools.count(1000)
#: handle -> (persistent?, func(msg))
self._handle_map = {}
#: Context -> set { handle, .. }
self._handles_by_respondent = {}
self.add_handler(self._on_del_route, DEL_ROUTE)
def __repr__(self):
return 'Router(%r)' % (self.broker,)
def _on_del_route(self, msg):
"""
Stub :data:`DEL_ROUTE` handler; fires 'disconnect' events on the
corresponding :attr:`_context_by_id` member. This is replaced by
:class:`mitogen.parent.RouteMonitor` in an upgraded context.
"""
LOG.error('%r._on_del_route() %r', self, msg)
if not msg.is_dead:
target_id_s, _, name = msg.data.partition(b(':'))
target_id = int(target_id_s, 10)
if target_id not in self._context_by_id:
LOG.debug('DEL_ROUTE for unknown ID %r: %r', target_id, msg)
return
fire(self._context_by_id[target_id], 'disconnect')
def _on_stream_disconnect(self, stream):
for context in self._context_by_id.values():
stream_ = self._stream_by_id.get(context.context_id)
if stream_ is stream:
del self._stream_by_id[context.context_id]
context.on_disconnect()
broker_exit_msg = 'Broker has exitted'
def _on_broker_exit(self):
while self._handle_map:
_, (_, func, _, _) = self._handle_map.popitem()
func(Message.dead(self.broker_exit_msg))
def myself(self):
"""
Return a :class:`Context` referring to the current process.
"""
return self.context_class(
router=self,
context_id=mitogen.context_id,
name='self',
)
def context_by_id(self, context_id, via_id=None, create=True, name=None):
"""
Messy factory/lookup function to find a context by its ID, or construct
it. In future this will be replaced by a much more sensible interface.
"""
context = self._context_by_id.get(context_id)
if create and not context:
context = self.context_class(self, context_id, name=name)
if via_id is not None:
context.via = self.context_by_id(via_id)
self._context_by_id[context_id] = context
return context
def register(self, context, stream):
"""
Register a newly constructed context and its associated stream, and add
the stream's receive side to the I/O multiplexer. This method remains
public while the design has not yet settled.
"""
_v and LOG.debug('register(%r, %r)', context, stream)
self._stream_by_id[context.context_id] = stream
self._context_by_id[context.context_id] = context
self.broker.start_receive(stream)
listen(stream, 'disconnect', lambda: self._on_stream_disconnect(stream))
def stream_by_id(self, dst_id):
"""
Return the :class:`Stream` that should be used to communicate with
`dst_id`. If a specific route for `dst_id` is not known, a reference to
the parent context's stream is returned.
"""
parent = self._stream_by_id.get(mitogen.parent_id)
return self._stream_by_id.get(dst_id, parent)
def del_handler(self, handle):
"""
Remove the handle registered for `handle`
:raises KeyError:
The handle wasn't registered.
"""
_, _, _, respondent = self._handle_map.pop(handle)
if respondent:
self._handles_by_respondent[respondent].discard(handle)
def add_handler(self, fn, handle=None, persist=True,
policy=None, respondent=None):
"""
Invoke `fn(msg)` on the :class:`Broker` thread for each Message sent to
`handle` from this context. Unregister after one invocation if
`persist` is :data:`False`. If `handle` is :data:`None`, a new handle
is allocated and returned.
:param int handle:
If not :data:`None`, an explicit handle to register, usually one of
the ``mitogen.core.*`` constants. If unspecified, a new unused
handle will be allocated.
:param bool persist:
If :data:`False`, the handler will be unregistered after a single
message has been received.
:param Context respondent:
Context that messages to this handle are expected to be sent from.
If specified, arranges for a dead message to be delivered to `fn`
when disconnection of the context is detected.
In future `respondent` will likely also be used to prevent other
contexts from sending messages to the handle.
:param function policy:
Function invoked as `policy(msg, stream)` where `msg` is a
:class:`mitogen.core.Message` about to be delivered, and `stream`
is the :class:`mitogen.core.Stream` on which it was received. The
function must return :data:`True`, otherwise an error is logged and
delivery is refused.
Two built-in policy functions exist:
* :func:`has_parent_authority`: requires the message arrived from a
parent context, or a context acting with a parent context's
authority (``auth_id``).
* :func:`mitogen.parent.is_immediate_child`: requires the
message arrived from an immediately connected child, for use in
messaging patterns where either something becomes buggy or
insecure by permitting indirect upstream communication.
In case of refusal, and the message's ``reply_to`` field is
nonzero, a :class:`mitogen.core.CallError` is delivered to the
sender indicating refusal occurred.
:return:
`handle`, or if `handle` was :data:`None`, the newly allocated
handle.
"""
handle = handle or next(self._last_handle)
_vv and IOLOG.debug('%r.add_handler(%r, %r, %r)', self, fn, handle, persist)
self._handle_map[handle] = persist, fn, policy, respondent
if respondent:
if respondent not in self._handles_by_respondent:
self._handles_by_respondent[respondent] = set()
listen(respondent, 'disconnect',
lambda: self._on_respondent_disconnect(respondent))
self._handles_by_respondent[respondent].add(handle)
return handle
refused_msg = 'refused by policy'
invalid_handle_msg = 'invalid handle'
too_large_msg = 'message too large (max %d bytes)'
respondent_disconnect_msg = 'the respondent Context has disconnected'
broker_shutdown_msg = 'Broker is shutting down'
no_route_msg = 'no route to %r, my ID is %r'
unidirectional_msg = (
'routing mode prevents forward of message from context %d via '
'context %d'
)
def _on_respondent_disconnect(self, context):
for handle in self._handles_by_respondent.pop(context, ()):
_, fn, _, _ = self._handle_map[handle]
fn(Message.dead(self.respondent_disconnect_msg))
del self._handle_map[handle]
def on_shutdown(self, broker):
"""Called during :meth:`Broker.shutdown`, informs callbacks registered
with :meth:`add_handle_cb` the connection is dead."""
_v and LOG.debug('%r.on_shutdown(%r)', self, broker)
fire(self, 'shutdown')
for handle, (persist, fn) in self._handle_map.iteritems():
_v and LOG.debug('%r.on_shutdown(): killing %r: %r', self, handle, fn)
fn(Message.dead(self.broker_shutdown_msg))
def _maybe_send_dead(self, msg, reason, *args):
if args:
reason %= args
LOG.debug('%r: %r is dead: %r', self, msg, reason)
if msg.reply_to and not msg.is_dead:
msg.reply(Message.dead(reason=reason), router=self)
def _invoke(self, msg, stream):
# IOLOG.debug('%r._invoke(%r)', self, msg)
try:
persist, fn, policy, respondent = self._handle_map[msg.handle]
except KeyError:
self._maybe_send_dead(msg, reason=self.invalid_handle_msg)
return
if respondent and not (msg.is_dead or
msg.src_id == respondent.context_id):
self._maybe_send_dead(msg, 'reply from unexpected context')
return
if policy and not policy(msg, stream):
self._maybe_send_dead(msg, self.refused_msg)
return
if not persist:
self.del_handler(msg.handle)
try:
fn(msg)
except Exception:
LOG.exception('%r._invoke(%r): %r crashed', self, msg, fn)
def _async_route(self, msg, in_stream=None):
"""
Arrange for `msg` to be forwarded towards its destination. If its
destination is the local context, then arrange for it to be dispatched
using the local handlers.
This is a lower overhead version of :meth:`route` that may only be
called from the :class:`Broker` thread.
:param Stream in_stream:
If not :data:`None`, the stream the message arrived on. Used for
performing source route verification, to ensure sensitive messages
such as ``CALL_FUNCTION`` arrive only from trusted contexts.
"""
_vv and IOLOG.debug('%r._async_route(%r, %r)', self, msg, in_stream)
if len(msg.data) > self.max_message_size:
self._maybe_send_dead(msg, self.too_large_msg % (
self.max_message_size,
))
return
# Perform source verification.
if in_stream:
parent = self._stream_by_id.get(mitogen.parent_id)
expect = self._stream_by_id.get(msg.auth_id, parent)
if in_stream != expect:
LOG.error('%r: bad auth_id: got %r via %r, not %r: %r',
self, msg.auth_id, in_stream, expect, msg)
return
if msg.src_id != msg.auth_id:
expect = self._stream_by_id.get(msg.src_id, parent)
if in_stream != expect:
LOG.error('%r: bad src_id: got %r via %r, not %r: %r',
self, msg.src_id, in_stream, expect, msg)
return
if in_stream.auth_id is not None:
msg.auth_id = in_stream.auth_id
# Maintain a set of IDs the source ever communicated with.
in_stream.egress_ids.add(msg.dst_id)
if msg.dst_id == mitogen.context_id:
return self._invoke(msg, in_stream)
out_stream = self._stream_by_id.get(msg.dst_id)
if out_stream is None:
out_stream = self._stream_by_id.get(mitogen.parent_id)
if out_stream is None:
self._maybe_send_dead(msg, self.no_route_msg,
msg.dst_id, mitogen.context_id)
return
if in_stream and self.unidirectional and not \
(in_stream.is_privileged or out_stream.is_privileged):
self._maybe_send_dead(msg, self.unidirectional_msg,
in_stream.remote_id, out_stream.remote_id)
return
out_stream._send(msg)
def route(self, msg):
"""
Arrange for the :class:`Message` `msg` to be delivered to its
destination using any relevant downstream context, or if none is found,
by forwarding the message upstream towards the master context. If `msg`
is destined for the local context, it is dispatched using the handles
registered with :meth:`add_handler`.
This may be called from any thread.
"""
self.broker.defer(self._async_route, msg)
class Broker(object):
"""
Responsible for handling I/O multiplexing in a private thread.
**Note:** This is the somewhat limited core version of the Broker class
used by child contexts. The master subclass is documented below.
"""
poller_class = Poller
_waker = None
_thread = None
#: Seconds grace to allow :class:`streams <Stream>` to shutdown gracefully
#: before force-disconnecting them during :meth:`shutdown`.
shutdown_timeout = 3.0
def __init__(self, poller_class=None):
self._alive = True
self._waker = Waker(self)
#: Arrange for `func(\*args, \**kwargs)` to be executed on the broker
#: thread, or immediately if the current thread is the broker thread.
#: Safe to call from any thread.
self.defer = self._waker.defer
self.poller = self.poller_class()
self.poller.start_receive(
self._waker.receive_side.fd,
(self._waker.receive_side, self._waker.on_receive)
)
self._thread = threading.Thread(
target=_profile_hook,
args=('broker', self._broker_main),
name='mitogen-broker'
)
self._thread.start()
self._waker.broker_ident = self._thread.ident
def start_receive(self, stream):
"""
Mark the :attr:`receive_side <Stream.receive_side>` on `stream` as
ready for reading. Safe to call from any thread. When the associated
file descriptor becomes ready for reading,
:meth:`BasicStream.on_receive` will be called.
"""
_vv and IOLOG.debug('%r.start_receive(%r)', self, stream)
side = stream.receive_side
assert side and side.fd is not None
self.defer(self.poller.start_receive,
side.fd, (side, stream.on_receive))
def stop_receive(self, stream):
"""
Mark the :attr:`receive_side <Stream.receive_side>` on `stream` as not
ready for reading. Safe to call from any thread.
"""
_vv and IOLOG.debug('%r.stop_receive(%r)', self, stream)
self.defer(self.poller.stop_receive, stream.receive_side.fd)
def _start_transmit(self, stream):
"""
Mark the :attr:`transmit_side <Stream.transmit_side>` on `stream` as
ready for writing. Must only be called from the Broker thread. When the
associated file descriptor becomes ready for writing,
:meth:`BasicStream.on_transmit` will be called.
"""
_vv and IOLOG.debug('%r._start_transmit(%r)', self, stream)
side = stream.transmit_side
assert side and side.fd is not None
self.poller.start_transmit(side.fd, (side, stream.on_transmit))
def _stop_transmit(self, stream):
"""
Mark the :attr:`transmit_side <Stream.receive_side>` on `stream` as not
ready for writing.
"""
_vv and IOLOG.debug('%r._stop_transmit(%r)', self, stream)
self.poller.stop_transmit(stream.transmit_side.fd)
def keep_alive(self):
"""
Return :data:`True` if any reader's :attr:`Side.keep_alive` attribute
is :data:`True`, or any :class:`Context` is still registered that is
not the master. Used to delay shutdown while some important work is in
progress (e.g. log draining).
"""
it = (side.keep_alive for (_, (side, _)) in self.poller.readers)
return sum(it, 0)
def defer_sync(self, func):
"""
Arrange for `func()` to execute on :class:`Broker` thread, blocking the
current thread until a result or exception is available.
:returns:
Return value of `func()`.
"""
latch = Latch()
def wrapper():
try:
latch.put(func())
except Exception:
latch.put(sys.exc_info()[1])
self.defer(wrapper)
res = latch.get()
if isinstance(res, Exception):
raise res
return res
def _call(self, stream, func):
"""
Call `func(self)`, catching any exception that might occur, logging it,
and force-disconnecting the related `stream`.
"""
try:
func(self)
except Exception:
LOG.exception('%r crashed', stream)
stream.on_disconnect(self)
def _loop_once(self, timeout=None):
"""
Execute a single :class:`Poller` wait, dispatching any IO events that
caused the wait to complete.
:param float timeout:
If not :data:`None`, maximum time in seconds to wait for events.
"""
_vv and IOLOG.debug('%r._loop_once(%r, %r)',
self, timeout, self.poller)
#IOLOG.debug('readers =\n%s', pformat(self.poller.readers))
#IOLOG.debug('writers =\n%s', pformat(self.poller.writers))
for side, func in self.poller.poll(timeout):
self._call(side.stream, func)
def _broker_exit(self):
"""
Forcefully call :meth:`Stream.on_disconnect` on any streams that failed
to shut down gracefully, then discard the :class:`Poller`.
"""
for _, (side, _) in self.poller.readers + self.poller.writers:
LOG.error('_broker_main() force disconnecting %r', side)
side.stream.on_disconnect(self)
self.poller.close()
def _broker_shutdown(self):
"""
Invoke :meth:`Stream.on_shutdown` for every active stream, then allow
up to :attr:`shutdown_timeout` seconds for the streams to unregister
themselves, logging an error if any did not unregister during the grace
period.
"""
for _, (side, _) in self.poller.readers + self.poller.writers:
self._call(side.stream, side.stream.on_shutdown)
deadline = time.time() + self.shutdown_timeout
while self.keep_alive() and time.time() < deadline:
self._loop_once(max(0, deadline - time.time()))
if self.keep_alive():
LOG.error('%r: some streams did not close gracefully. '
'The most likely cause for this is one or '
'more child processes still connected to '
'our stdout/stderr pipes.', self)
def _broker_main(self):
"""
Broker thread main function. Dispatches IO events until
:meth:`shutdown` is called.
"""
try:
while self._alive:
self._loop_once()
fire(self, 'shutdown')
self._broker_shutdown()
except Exception:
LOG.exception('_broker_main() crashed')
self._broker_exit()
fire(self, 'exit')
def shutdown(self):
"""
Request broker gracefully disconnect streams and stop. Safe to call
from any thread.
"""
_v and LOG.debug('%r.shutdown()', self)
def _shutdown():
self._alive = False
self.defer(_shutdown)
def join(self):
"""
Wait for the broker to stop, expected to be called after
:meth:`shutdown`.
"""
self._thread.join()
def __repr__(self):
return 'Broker(%#x)' % (id(self),)
class Dispatcher(object):
"""
Implementation of the :data:`CALL_FUNCTION` handle for a child context.
Listens on the child's main thread for messages sent by
:class:`mitogen.parent.CallChain` and dispatches the function calls they
describe.
If a :class:`mitogen.parent.CallChain` sending a message is in pipelined
mode, any exception that occurs is recorded, and causes all subsequent
calls with the same `chain_id` to fail with the same exception.
"""
def __init__(self, econtext):
self.econtext = econtext
#: Chain ID -> CallError if prior call failed.
self._error_by_chain_id = {}
self.recv = Receiver(router=econtext.router,
handle=CALL_FUNCTION,
policy=has_parent_authority)
listen(econtext.broker, 'shutdown', self.recv.close)
@classmethod
@takes_econtext
def forget_chain(cls, chain_id, econtext):
econtext.dispatcher._error_by_chain_id.pop(chain_id, None)
def _parse_request(self, msg):
data = msg.unpickle(throw=False)
_v and LOG.debug('_dispatch_one(%r)', data)
chain_id, modname, klass, func, args, kwargs = data
obj = import_module(modname)
if klass:
obj = getattr(obj, klass)
fn = getattr(obj, func)
if getattr(fn, 'mitogen_takes_econtext', None):
kwargs.setdefault('econtext', self.econtext)
if getattr(fn, 'mitogen_takes_router', None):
kwargs.setdefault('router', self.econtext.router)
return chain_id, fn, args, kwargs
def _dispatch_one(self, msg):
try:
chain_id, fn, args, kwargs = self._parse_request(msg)
except Exception:
return None, CallError(sys.exc_info()[1])
if chain_id in self._error_by_chain_id:
return chain_id, self._error_by_chain_id[chain_id]
try:
return chain_id, fn(*args, **kwargs)
except Exception:
e = CallError(sys.exc_info()[1])
if chain_id is not None:
self._error_by_chain_id[chain_id] = e
return chain_id, e
def _dispatch_calls(self):
for msg in self.recv:
chain_id, ret = self._dispatch_one(msg)
_v and LOG.debug('_dispatch_calls: %r -> %r', msg, ret)
if msg.reply_to:
msg.reply(ret)
elif isinstance(ret, CallError) and chain_id is None:
LOG.error('No-reply function call failed: %s', ret)
def run(self):
if self.econtext.config.get('on_start'):
self.econtext.config['on_start'](self.econtext)
_profile_hook('main', self._dispatch_calls)
class ExternalContext(object):
"""
External context implementation.
.. attribute:: broker
The :class:`mitogen.core.Broker` instance.
.. attribute:: context
The :class:`mitogen.core.Context` instance.
.. attribute:: channel
The :class:`mitogen.core.Channel` over which :data:`CALL_FUNCTION`
requests are received.
.. attribute:: stdout_log
The :class:`mitogen.core.IoLogger` connected to ``stdout``.
.. attribute:: importer
The :class:`mitogen.core.Importer` instance.
.. attribute:: stdout_log
The :class:`IoLogger` connected to ``stdout``.
.. attribute:: stderr_log
The :class:`IoLogger` connected to ``stderr``.
.. method:: _dispatch_calls
Implementation for the main thread in every child context.
"""
detached = False
def __init__(self, config):
self.config = config
def _on_broker_exit(self):
if not self.config['profiling']:
os.kill(os.getpid(), signal.SIGTERM)
def _service_stub_main(self, msg):
import mitogen.service
pool = mitogen.service.get_or_create_pool(router=self.router)
pool._receiver._on_receive(msg)
def _on_call_service_msg(self, msg):
"""
Stub service handler. Start a thread to import the mitogen.service
implementation from, and deliver the message to the newly constructed
pool. This must be done as CALL_SERVICE for e.g. PushFileService may
race with a CALL_FUNCTION blocking the main thread waiting for a result
from that service.
"""
if not msg.is_dead:
th = threading.Thread(target=self._service_stub_main, args=(msg,))
th.start()
def _on_shutdown_msg(self, msg):
_v and LOG.debug('_on_shutdown_msg(%r)', msg)
if not msg.is_dead:
self.broker.shutdown()
def _on_parent_disconnect(self):
if self.detached:
mitogen.parent_ids = []
mitogen.parent_id = None
LOG.info('Detachment complete')
else:
_v and LOG.debug('%r: parent stream is gone, dying.', self)
self.broker.shutdown()
def detach(self):
self.detached = True
stream = self.router.stream_by_id(mitogen.parent_id)
if stream: # not double-detach()'d
os.setsid()
self.parent.send_await(Message(handle=DETACHING))
LOG.info('Detaching from %r; parent is %s', stream, self.parent)
for x in range(20):
pending = self.broker.defer_sync(lambda: stream.pending_bytes())
if not pending:
break
time.sleep(0.05)
if pending:
LOG.error('Stream had %d bytes after 2000ms', pending)
self.broker.defer(stream.on_disconnect, self.broker)
def _setup_master(self):
Router.max_message_size = self.config['max_message_size']
if self.config['profiling']:
enable_profiling()
self.broker = Broker()
self.router = Router(self.broker)
self.router.debug = self.config.get('debug', False)
self.router.undirectional = self.config['unidirectional']
self.router.add_handler(
fn=self._on_shutdown_msg,
handle=SHUTDOWN,
policy=has_parent_authority,
)
self.router.add_handler(
fn=self._on_call_service_msg,
handle=CALL_SERVICE,
policy=has_parent_authority,
)
self.master = Context(self.router, 0, 'master')
parent_id = self.config['parent_ids'][0]
if parent_id == 0:
self.parent = self.master
else:
self.parent = Context(self.router, parent_id, 'parent')
in_fd = self.config.get('in_fd', 100)
out_fd = self.config.get('out_fd', 1)
self.stream = Stream(self.router, parent_id)
self.stream.name = 'parent'
self.stream.accept(in_fd, out_fd)
self.stream.receive_side.keep_alive = False
listen(self.stream, 'disconnect', self._on_parent_disconnect)
listen(self.broker, 'exit', self._on_broker_exit)
os.close(in_fd)
def _reap_first_stage(self):
try:
os.wait() # Reap first stage.
except OSError:
pass # No first stage exists (e.g. fakessh)
def _setup_logging(self):
self.log_handler = LogHandler(self.master)
root = logging.getLogger()
root.setLevel(self.config['log_level'])
root.handlers = [self.log_handler]
if self.config['debug']:
enable_debug_logging()
def _setup_importer(self):
importer = self.config.get('importer')
if importer:
importer._install_handler(self.router)
importer._context = self.parent
else:
core_src_fd = self.config.get('core_src_fd', 101)
if core_src_fd:
fp = os.fdopen(core_src_fd, 'rb', 1)
try:
core_src = fp.read()
# Strip "ExternalContext.main()" call from last line.
core_src = b('\n').join(core_src.splitlines()[:-1])
finally:
fp.close()
else:
core_src = None
importer = Importer(
self.router,
self.parent,
core_src,
self.config.get('whitelist', ()),
self.config.get('blacklist', ()),
)
self.importer = importer
self.router.importer = importer
sys.meta_path.insert(0, self.importer)
def _setup_package(self):
global mitogen
mitogen = imp.new_module('mitogen')
mitogen.__package__ = 'mitogen'
mitogen.__path__ = []
mitogen.__loader__ = self.importer
mitogen.main = lambda *args, **kwargs: (lambda func: None)
mitogen.core = sys.modules['__main__']
mitogen.core.__file__ = 'x/mitogen/core.py' # For inspect.getsource()
mitogen.core.__loader__ = self.importer
sys.modules['mitogen'] = mitogen
sys.modules['mitogen.core'] = mitogen.core
del sys.modules['__main__']
def _setup_globals(self):
mitogen.is_master = False
mitogen.__version__ = self.config['version']
mitogen.context_id = self.config['context_id']
mitogen.parent_ids = self.config['parent_ids'][:]
mitogen.parent_id = mitogen.parent_ids[0]
def _nullify_stdio(self):
"""
Open /dev/null to replace stdin, and stdout/stderr temporarily. In case
of odd startup, assume we may be allocated a standard handle.
"""
fd = os.open('/dev/null', os.O_RDWR)
try:
for stdfd in (0, 1, 2):
if fd != stdfd:
os.dup2(fd, stdfd)
finally:
if fd not in (0, 1, 2):
os.close(fd)
def _setup_stdio(self):
# When sys.stdout was opened by the runtime, overwriting it will not
# close FD 1. However when forking from a child that previously used
# fdopen(), overwriting it /will/ close FD 1. So we must swallow the
# close before IoLogger overwrites FD 1, otherwise its new FD 1 will be
# clobbered. Additionally, stdout must be replaced with /dev/null prior
# to stdout.close(), since if block buffering was active in the parent,
# any pre-fork buffered data will be flushed on close(), corrupting the
# connection to the parent.
self._nullify_stdio()
sys.stdout.close()
self._nullify_stdio()
self.stdout_log = IoLogger(self.broker, 'stdout', 1)
self.stderr_log = IoLogger(self.broker, 'stderr', 2)
# Reopen with line buffering.
sys.stdout = os.fdopen(1, 'w', 1)
def main(self):
self._setup_master()
try:
try:
self._setup_logging()
self._setup_importer()
self._reap_first_stage()
if self.config.get('setup_package', True):
self._setup_package()
self._setup_globals()
if self.config.get('setup_stdio', True):
self._setup_stdio()
self.dispatcher = Dispatcher(self)
self.router.register(self.parent, self.stream)
self.log_handler.uncork()
sys.executable = os.environ.pop('ARGV0', sys.executable)
_v and LOG.debug('Connected to %s; my ID is %r, PID is %r',
self.parent, mitogen.context_id, os.getpid())
_v and LOG.debug('Recovered sys.executable: %r', sys.executable)
self.dispatcher.run()
_v and LOG.debug('ExternalContext.main() normal exit')
except KeyboardInterrupt:
LOG.debug('KeyboardInterrupt received, exiting gracefully.')
except BaseException:
LOG.exception('ExternalContext.main() crashed')
raise
finally:
self.broker.shutdown()
self.broker.join()
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