56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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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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*/
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#pragma once
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#include <folly/Executor.h>
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namespace folly {
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/*
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* A DrivableExecutor can be driven via its drive() method
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* Examples include EventBase (via loopOnce()) and ManualExecutor
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* (via makeProgress()).
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*
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* This interface is most handy in conjunction with
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* Future<T>::getVia(DrivableExecutor*) and
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* Future<T>::waitVia(DrivableExecutor*)
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*
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* These call drive() * repeatedly until the Future is fulfilled.
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* getVia() returns the value (or throws the exception) and waitVia() returns
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* the same Future for chainability.
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*
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* These will be most helpful in tests, for instance if you need to pump a mock
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* EventBase until Futures complete.
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*/
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class DrivableExecutor : public virtual Executor {
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public:
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~DrivableExecutor() override = default;
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// Make progress on this Executor's work.
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//
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// Drive *must not* busy wait if there is no work to do. Instead,
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// sleep (using a semaphore or similar) until at least one event is
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// processed.
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// I.e. make_future().via(foo).then(...).getVia(DrivableExecutor)
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// must not spin, even though nothing happens on the drivable
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// executor.
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virtual void drive() = 0;
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};
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} // namespace folly
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