#
# Copyright (c) SAS Institute Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#


from twisted.internet import defer


class Serializer(object):

    def __init__(self):
        self._lock = defer.DeferredLock()
        self._waiting = {}

    def call(self, func, args=(), kwargs=None, collapsible=False):
        d = self._lock.acquire()
        self._waiting[d] = collapsible
        if not kwargs:
            kwargs = {}
        @d.addCallback
        def _locked(_):
            if collapsible and len(self._waiting) > 1:
                # Superseded
                return
            return func(*args, **kwargs)
        @d.addBoth
        def _unlock(result):
            self._lock.release()
            del self._waiting[d]
            return result
        return d

#
# Copyright (c) SAS Institute Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#


from twisted.internet import defer


class Serializer(object):

    def __init__(self):
        self._lock = defer.DeferredLock()
        self._waiting = {}

    def call(self, func, args=(), kwargs=None, collapsible=False):
        d = self._lock.acquire()
        self._waiting[d] = collapsible
        if not kwargs:
            kwargs = {}
        @d.addCallback
        def _locked(_):
            if collapsible and len(self._waiting) > 1:
                # Superseded
                return
            return func(*args, **kwargs)
        @d.addBoth
        def _unlock(result):
            del self._waiting[d]
            self._lock.release()
            return result
        return d

Fix Serializer locking bug that caused it to skip calls it should have made