56 lines
1.9 KiB
Python
56 lines
1.9 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from synapse.util.async import ObservableDeferred
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class ResponseCache(object):
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"""
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This caches a deferred response. Until the deferred completes it will be
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returned from the cache. This means that if the client retries the request
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while the response is still being computed, that original response will be
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used rather than trying to compute a new response.
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"""
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def __init__(self, hs, timeout_ms=0):
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self.pending_result_cache = {} # Requests that haven't finished yet.
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self.clock = hs.get_clock()
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self.timeout_sec = timeout_ms / 1000.
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def get(self, key):
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result = self.pending_result_cache.get(key)
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if result is not None:
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return result.observe()
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else:
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return None
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def set(self, key, deferred):
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result = ObservableDeferred(deferred, consumeErrors=True)
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self.pending_result_cache[key] = result
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def remove(r):
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if self.timeout_sec:
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self.clock.call_later(
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self.timeout_sec,
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self.pending_result_cache.pop, key, None,
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)
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else:
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self.pending_result_cache.pop(key, None)
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return r
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result.addBoth(remove)
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return result.observe()
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