mitogen/mitogen/service.py

# 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,
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


import logging

import mitogen.core
import mitogen.master
from mitogen.core import LOG


class Service(object):
    #: If ``None``, a handle is dynamically allocated, otherwise the fixed
    #: integer handle to use.
    handle = None
    max_message_size = 0

    def __init__(self, router):
        self.router = router
        self.recv = mitogen.core.Receiver(router, self.handle)
        self.handle = self.recv.handle
        self.running = True

    def validate_args(self, args):
        return True

    def run_once(self):
        try:
            msg = self.recv.get()
        except mitogen.core.ChannelError, e:
            # Channel closed due to broker shutdown, exit gracefully.
            LOG.debug('%r: channel closed: %s', self, e)
            self.running = False
            return

        if len(msg.data) > self.max_message_size:
            LOG.error('%r: larger than permitted size: %r', self, msg)
            msg.reply(mitogen.core.CallError('Message size exceeded'))
            return

        args = msg.unpickle(throw=False)
        if ( args == mitogen.core._DEAD or
             isinstance(args, mitogen.core.CallError) or
             not self.validate_args(args)):
            LOG.warning('Received junk message: %r', args)
            return

        try:
            msg.reply(self.dispatch(args, msg))
        except Exception, e:
            LOG.exception('While invoking %r.dispatch()', self)
            msg.reply(mitogen.core.CallError(e))

    def run(self):
        while self.running:
            self.run_once()


class Pool(object):
    def __init__(self, router, services, size=1):
        self.services = list(services)
        self.select = mitogen.master.Select()



def call(context, handle, obj):
    msg = mitogen.core.Message.pickled(obj, handle=handle)
    recv = context.send_async(msg)
    return recv.get().unpickle()