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430 lines
16 KiB
Python
430 lines
16 KiB
Python
# Copyright 2017, David Wilson
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# 3. Neither the name of the copyright holder nor the names of its contributors
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# may be used to endorse or promote products derived from this software without
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# specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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"""
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Classes in this file define Mitogen 'services' that run (initially) within the
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connection multiplexer process that is forked off the top-level controller
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process.
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Once a worker process connects to a multiplexer process
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(Connection._connect()), it communicates with these services to establish new
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connections, grant access to files by children, and register for notification
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when a child has completed a job.
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"""
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from __future__ import absolute_import
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from __future__ import unicode_literals
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import logging
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import os
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import os.path
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import sys
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import threading
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import mitogen
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import mitogen.service
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import ansible_mitogen.module_finder
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import ansible_mitogen.target
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LOG = logging.getLogger(__name__)
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if sys.version_info[0] == 3:
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def reraise(tp, value, tb):
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if value is None:
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value = tp()
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if value.__traceback__ is not tb:
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raise value.with_traceback(tb)
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raise value
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else:
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exec(
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"def reraise(tp, value, tb=None):\n"
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" raise tp, value, tb\n"
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)
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class Error(Exception):
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pass
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class ContextService(mitogen.service.Service):
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"""
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Used by workers to fetch the single Context instance corresponding to a
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connection configuration, creating the matching connection if it does not
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exist.
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For connection methods and their parameters, see:
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https://mitogen.readthedocs.io/en/latest/api.html#context-factories
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This concentrates connections in the top-level process, which may become a
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bottleneck. The bottleneck can be removed using per-CPU connection
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processes and arranging for the worker to select one according to a hash of
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the connection parameters (sharding).
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"""
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max_interpreters = int(os.getenv('MITOGEN_MAX_INTERPRETERS', '20'))
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def __init__(self, *args, **kwargs):
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super(ContextService, self).__init__(*args, **kwargs)
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self._lock = threading.Lock()
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#: Records the :meth:`get` result dict for successful calls, returned
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#: for identical subsequent calls. Keyed by :meth:`key_from_kwargs`.
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self._response_by_key = {}
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#: List of :class:`mitogen.core.Latch` awaiting the result for a
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#: particular key.
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self._latches_by_key = {}
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#: Mapping of :class:`mitogen.core.Context` -> reference count. Each
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#: call to :meth:`get` increases this by one. Calls to :meth:`put`
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#: decrease it by one.
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self._refs_by_context = {}
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#: List of contexts in creation order by via= parameter. When
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#: :attr:`max_interpreters` is reached, the most recently used context
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#: is destroyed to make room for any additional context.
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self._lru_by_via = {}
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#: :meth:`key_from_kwargs` result by Context.
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self._key_by_context = {}
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@mitogen.service.expose(mitogen.service.AllowParents())
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@mitogen.service.arg_spec({
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'context': mitogen.core.Context
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})
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def put(self, context):
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"""
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Return a reference, making it eligable for recycling once its reference
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count reaches zero.
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"""
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LOG.debug('%r.put(%r)', self, context)
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if self._refs_by_context.get(context, 0) == 0:
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LOG.warning('%r.put(%r): refcount was 0. shutdown_all called?',
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self, context)
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return
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self._refs_by_context[context] -= 1
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def key_from_kwargs(self, **kwargs):
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"""
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Generate a deduplication key from the request.
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"""
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out = []
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stack = [kwargs]
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while stack:
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obj = stack.pop()
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if isinstance(obj, dict):
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stack.extend(sorted(obj.items()))
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elif isinstance(obj, (list, tuple)):
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stack.extend(obj)
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else:
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out.append(str(obj))
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return ''.join(out)
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def _produce_response(self, key, response):
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"""
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Reply to every waiting request matching a configuration key with a
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response dictionary, deleting the list of waiters when done.
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:param str key:
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Result of :meth:`key_from_kwargs`
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:param dict response:
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Response dictionary
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:returns:
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Number of waiters that were replied to.
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"""
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self._lock.acquire()
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try:
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latches = self._latches_by_key.pop(key)
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count = len(latches)
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for latch in latches:
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latch.put(response)
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finally:
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self._lock.release()
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return count
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def _shutdown(self, context, lru=None, new_context=None):
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"""
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Arrange for `context` to be shut down, and optionally add `new_context`
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to the LRU list while holding the lock.
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"""
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LOG.info('%r._shutdown(): shutting down %r', self, context)
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context.shutdown()
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key = self._key_by_context[context]
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self._lock.acquire()
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try:
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del self._response_by_key[key]
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del self._refs_by_context[context]
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del self._key_by_context[context]
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if lru and context in lru:
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lru.remove(context)
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if new_context:
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lru.append(new_context)
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finally:
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self._lock.release()
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def _update_lru(self, new_context, spec, via):
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"""
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Update the LRU ("MRU"?) list associated with the connection described
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by `kwargs`, destroying the most recently created context if the list
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is full. Finally add `new_context` to the list.
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"""
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lru = self._lru_by_via.setdefault(via, [])
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if len(lru) < self.max_interpreters:
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lru.append(new_context)
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return
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for context in reversed(lru):
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if self._refs_by_context[context] == 0:
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break
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else:
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LOG.warning('via=%r reached maximum number of interpreters, '
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'but they are all marked as in-use.', via)
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return
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self._shutdown(context, lru=lru, new_context=new_context)
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@mitogen.service.expose(mitogen.service.AllowParents())
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def shutdown_all(self):
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"""
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For testing use, arrange for all connections to be shut down.
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"""
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for context in list(self._key_by_context):
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self._shutdown(context)
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self._lru_by_via = {}
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def _on_stream_disconnect(self, stream):
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"""
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Respond to Stream disconnection by deleting any record of contexts
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reached via that stream. This method runs in the Broker thread and must
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not to block.
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"""
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# TODO: there is a race between creation of a context and disconnection
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# of its related stream. An error reply should be sent to any message
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# in _latches_by_key below.
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self._lock.acquire()
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try:
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for context, key in list(self._key_by_context.items()):
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if context.context_id in stream.routes:
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LOG.info('Dropping %r due to disconnect of %r',
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context, stream)
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self._response_by_key.pop(key, None)
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self._latches_by_key.pop(key, None)
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self._refs_by_context.pop(context, None)
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self._lru_by_via.pop(context, None)
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self._refs_by_context.pop(context, None)
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finally:
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self._lock.release()
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ALWAYS_PRELOAD = (
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'ansible.module_utils.basic',
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'ansible.module_utils.json_utils',
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'ansible.release',
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'ansible_mitogen.runner',
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'ansible_mitogen.target',
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'mitogen.fork',
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'mitogen.service',
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)
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def _send_module_forwards(self, context):
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for fullname in self.ALWAYS_PRELOAD:
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self.router.responder.forward_module(context, fullname)
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def _connect(self, key, spec, via=None):
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"""
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Actual connect implementation. Arranges for the Mitogen connection to
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be created and enqueues an asynchronous call to start the forked task
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parent in the remote context.
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:param key:
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Deduplication key representing the connection configuration.
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:param spec:
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Connection specification.
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:returns:
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Dict like::
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{
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'context': mitogen.core.Context or None,
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'init_child_result': {
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'fork_context': mitogen.core.Context,
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'home_dir': str or None,
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},
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'msg': str or None
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}
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Where `context` is a reference to the newly constructed context,
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`init_child_result` is the result of executing
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:func:`ansible_mitogen.target.init_child` in that context, `msg` is
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an error message and the remaining fields are :data:`None`, or
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`msg` is :data:`None` and the remaining fields are set.
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"""
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try:
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method = getattr(self.router, spec['method'])
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except AttributeError:
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raise Error('unsupported method: %(transport)s' % spec)
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context = method(via=via, unidirectional=True, **spec['kwargs'])
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if via and spec.get('enable_lru'):
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self._update_lru(context, spec, via)
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else:
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# For directly connected contexts, listen to the associated
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# Stream's disconnect event and use it to invalidate dependent
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# Contexts.
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stream = self.router.stream_by_id(context.context_id)
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mitogen.core.listen(stream, 'disconnect',
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lambda: self._on_stream_disconnect(stream))
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self._send_module_forwards(context)
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init_child_result = context.call(ansible_mitogen.target.init_child)
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if os.environ.get('MITOGEN_DUMP_THREAD_STACKS'):
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from mitogen import debug
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context.call(debug.dump_to_logger)
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self._key_by_context[context] = key
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self._refs_by_context[context] = 0
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return {
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'context': context,
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'init_child_result': init_child_result,
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'msg': None,
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}
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def _wait_or_start(self, spec, via=None):
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latch = mitogen.core.Latch()
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key = self.key_from_kwargs(via=via, **spec)
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self._lock.acquire()
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try:
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response = self._response_by_key.get(key)
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if response is not None:
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self._refs_by_context[response['context']] += 1
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latch.put(response)
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return latch
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latches = self._latches_by_key.setdefault(key, [])
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first = len(latches) == 0
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latches.append(latch)
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finally:
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self._lock.release()
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if first:
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# I'm the first requestee, so I will create the connection.
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try:
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response = self._connect(key, spec, via=via)
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count = self._produce_response(key, response)
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# Only record the response for non-error results.
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self._response_by_key[key] = response
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# Set the reference count to the number of waiters.
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self._refs_by_context[response['context']] += count
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except Exception:
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self._produce_response(key, sys.exc_info())
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return latch
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@mitogen.service.expose(mitogen.service.AllowParents())
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@mitogen.service.arg_spec({
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'stack': list
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})
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def get(self, msg, stack):
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"""
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Return a Context referring to an established connection with the given
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configuration, establishing new connections as necessary.
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:param list stack:
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Connection descriptions. Each element is a dict containing 'method'
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and 'kwargs' keys describing the Router method and arguments.
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Subsequent elements are proxied via the previous.
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:returns dict:
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* context: mitogen.master.Context or None.
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* init_child_result: Result of :func:`init_child`.
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* msg: StreamError exception text or None.
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* method_name: string failing method name.
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"""
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via = None
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for spec in stack:
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try:
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result = self._wait_or_start(spec, via=via).get()
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if isinstance(result, tuple): # exc_info()
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reraise(*result)
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via = result['context']
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except mitogen.core.StreamError as e:
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return {
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'context': None,
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'init_child_result': None,
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'method_name': spec['method'],
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'msg': str(e),
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}
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return result
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class ModuleDepService(mitogen.service.Service):
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"""
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Scan a new-style module and produce a cached mapping of module_utils names
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to their resolved filesystem paths.
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"""
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def __init__(self, *args, **kwargs):
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super(ModuleDepService, self).__init__(*args, **kwargs)
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self._cache = {}
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def _get_builtin_names(self, builtin_path, resolved):
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return [
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fullname
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for fullname, path, is_pkg in resolved
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if os.path.abspath(path).startswith(builtin_path)
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]
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def _get_custom_tups(self, builtin_path, resolved):
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return [
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(fullname, path, is_pkg)
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for fullname, path, is_pkg in resolved
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if not os.path.abspath(path).startswith(builtin_path)
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]
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@mitogen.service.expose(policy=mitogen.service.AllowParents())
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@mitogen.service.arg_spec({
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'module_name': mitogen.core.UnicodeType,
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'module_path': mitogen.core.FsPathTypes,
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'search_path': tuple,
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'builtin_path': mitogen.core.FsPathTypes,
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'context': mitogen.core.Context,
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})
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def scan(self, module_name, module_path, search_path, builtin_path, context):
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key = (module_name, search_path)
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if key not in self._cache:
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resolved = ansible_mitogen.module_finder.scan(
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module_name=module_name,
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module_path=module_path,
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search_path=tuple(search_path) + (builtin_path,),
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)
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builtin_path = os.path.abspath(builtin_path)
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builtin = self._get_builtin_names(builtin_path, resolved)
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custom = self._get_custom_tups(builtin_path, resolved)
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self._cache[key] = {
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'builtin': builtin,
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'custom': custom,
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}
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return self._cache[key]
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