59 lines
1.9 KiB
C++
59 lines
1.9 KiB
C++
/*
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* Copyright 2021 The Android Open Source Project
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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 <Tracing/LocklessStack.h>
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#include <android-base/thread_annotations.h>
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#include <ftl/small_vector.h>
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#include <semaphore.h>
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#include <utils/Singleton.h>
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#include <mutex>
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#include <queue>
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#include <thread>
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namespace android {
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// Executes tasks off the main thread.
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class BackgroundExecutor : public Singleton<BackgroundExecutor> {
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public:
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BackgroundExecutor();
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~BackgroundExecutor();
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using Callbacks = ftl::SmallVector<std::function<void()>, 10>;
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// Queues callbacks onto a work queue to be executed by a background thread.
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// Note that this is not thread-safe - a single producer is assumed.
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void sendCallbacks(Callbacks&& tasks);
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private:
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sem_t mSemaphore;
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std::atomic_bool mDone = false;
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// Sequence number for work items.
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// Work items are batched by sequence number. Work items for earlier sequence numbers are
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// executed first. Work items with the same sequence number are executed in the same order they
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// were added to the stack (meaning the stack must reverse the order after popping from the
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// queue)
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int32_t mSequence = 0;
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struct Work {
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int32_t sequence = 0;
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Callbacks tasks;
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};
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LocklessStack<Work> mWorks;
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std::thread mThread;
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};
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} // namespace android
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