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mitogen/ansible_mitogen/services.py

269 lines
9.5 KiB
Python

# 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.
"""
Classes in this file define Mitogen 'services' that run (initially) within the
connection multiplexer process that is forked off the top-level controller
process.
Once a worker process connects to a multiplexer process
(Connection._connect()), it communicates with these services to establish new
connections, grant access to files by children, and register for notification
when a child has completed a job.
"""
from __future__ import absolute_import
import logging
import os.path
import threading
import zlib
import mitogen
import mitogen.service
import ansible_mitogen.target
LOG = logging.getLogger(__name__)
class Error(Exception):
pass
class ContextService(mitogen.service.DeduplicatingService):
"""
Used by workers to fetch the single Context instance corresponding to a
connection configuration, creating the matching connection if it does not
exist.
For connection methods and their parameters, see:
https://mitogen.readthedocs.io/en/latest/api.html#context-factories
This concentrates connections in the top-level process, which may become a
bottleneck. The bottleneck can be removed using per-CPU connection
processes and arranging for the worker to select one according to a hash of
the connection parameters (sharding).
"""
handle = 500
max_message_size = 1000
@mitogen.service.expose(mitogen.service.AllowParents())
@mitogen.service.arg_spec({
'method_name': str
})
def connect(self, method_name, discriminator=None, **kwargs):
"""
Return a Context referring to an established connection with the given
configuration, establishing a new connection as necessary.
:param str method_name:
The :class:`mitogen.parent.Router` connection method to use.
:param discriminator:
Mixed into the key used to select an existing connection, to allow
intentional duplicate connections to be created.
:param dict kwargs:
Keyword arguments passed to `mitogen.master.Router.[method_name]()`.
:returns tuple:
Tuple of `(context, home_dir)`, where:
* `context` is the mitogen.master.Context referring to the
target context.
* `home_dir` is a cached copy of the remote directory.
"""
method = getattr(self.router, method_name, None)
if method is None:
raise Error('no such Router method: %s' % (method_name,))
try:
context = method(**kwargs)
except mitogen.core.StreamError as e:
return {
'context': None,
'home_dir': None,
'msg': str(e),
}
home_dir = context.call(os.path.expanduser, '~')
# We don't need to wait for the result of this. Ideally we'd check its
# return value somewhere, but logs will catch a failure anyway.
context.call_async(ansible_mitogen.target.start_fork_parent)
return {
'context': context,
'home_dir': home_dir,
'msg': None,
}
class FileService(mitogen.service.Service):
"""
Primitive latency-inducing file server for old-style incantations of the
module runner. This is to be replaced later with a scheme that forwards
files known to be missing without the target having to ask for them,
avoiding a corresponding roundtrip per file.
Paths must be explicitly added to the service by a trusted context before
they will be served to an untrusted context.
"""
handle = 501
max_message_size = 1000
unregistered_msg = 'Path is not registered with FileService.'
def __init__(self, router):
super(FileService, self).__init__(router)
self._paths = {}
@mitogen.service.expose(policy=mitogen.service.AllowParents())
@mitogen.service.arg_spec({
'path': basestring
})
def register(self, path):
"""
Authorize a path for access by child contexts. Calling this repeatedly
with the same path is harmless.
:param str path:
File path.
"""
if path not in self._paths:
LOG.debug('%r: registering %r', self, path)
with open(path, 'rb') as fp:
self._paths[path] = zlib.compress(fp.read())
@mitogen.service.expose(policy=mitogen.service.AllowAny())
@mitogen.service.arg_spec({
'path': basestring
})
def fetch(self, path):
"""
Fetch a file's data.
:param str path:
File path.
:returns:
The file data.
:raises mitogen.core.CallError:
The path was not registered.
"""
if path not in self._paths:
raise mitogen.core.CallError(self.unregistered_msg)
LOG.debug('Serving %r', path)
return self._paths[path]
class JobResultService(mitogen.service.Service):
"""
Receive the result of a task from a child and forward it to interested
listeners. If no listener exists, store the result until it is requested.
Storing results in an intermediary service allows:
* the lifetime of the worker to be decoupled from the lifetime of the job,
* for new and unrelated workers to request the job result after the original
worker that spawned it has exitted,
* for synchronous and asynchronous jobs to be treated identically,
* for latency-free polling and waiting on job results, and
* for Ansible job IDs to be be used to refer to a job in preference to
Mitogen-internal identifiers such as Sender and Context.
Results are keyed by job ID.
"""
handle = 502
max_message_size = 1048576 * 64
def __init__(self, router):
super(JobResultService, self).__init__(router)
self._lock = threading.Lock()
self._result_by_job_id = {}
self._sender_by_job_id = {}
@mitogen.service.expose(mitogen.service.AllowParents())
@mitogen.service.arg_spec({
'job_id': str,
'sender': mitogen.core.Sender,
})
def listen(self, job_id, sender):
"""
Register to receive the result of a job when it becomes available.
:param str job_id:
Job ID to listen for.
:param mitogen.core.Sender sender:
Sender on which to deliver the job result.
"""
LOG.debug('%r.listen(job_id=%r, sender=%r)', self, job_id, sender)
with self._lock:
if job_id in self._sender_by_job_id:
raise Error('Listener already exists for job: %s' % (job_id,))
self._sender_by_job_id[job_id] = sender
@mitogen.service.expose(mitogen.service.AllowParents())
@mitogen.service.arg_spec({
'job_id': basestring,
})
def get(self, job_id):
"""
Return a job's result if it is available, otherwise return immediately.
The job result is forgotten once it has been returned by this method.
:param str job_id:
Job ID to return.
:returns:
Job result dictionary, or :data:`None`.
"""
LOG.debug('%r.get(job_id=%r)', self, job_id)
with self._lock:
return self._result_by_job_id.pop(job_id, None)
@mitogen.service.expose(mitogen.service.AllowAny())
@mitogen.service.arg_spec({
'job_id': basestring,
'result': dict
})
def push(self, job_id, result):
"""
Deliver a job's result from a child context, notifying any listener
registred via :meth:`listen` of the result.
:param str job_id:
Job ID whose result is being pushed.
:param dict result:
Job result dictionary.
"""
LOG.debug('%r.push(job_id=%r, result=%r)', self, job_id, result)
with self._lock:
if job_id in self._result_by_job_id:
raise Error('Result already exists for job: %s' % (job_id,))
sender = self._sender_by_job_id.pop(job_id, None)
if sender:
sender.send(result)
else:
self._result_by_job_id[job_id] = result