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/*
* Copyright (C) 2019 The Android Open Source Project
*
* 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.
*/
#ifndef FRAMEWORKS_BASE_COMMONPOOL_H
#define FRAMEWORKS_BASE_COMMONPOOL_H
#include "utils/Macros.h"
#include <log/log.h>
#include <condition_variable>
#include <functional>
#include <future>
#include <mutex>
namespace android {
namespace uirenderer {
template <class T, int SIZE>
class ArrayQueue {
PREVENT_COPY_AND_ASSIGN(ArrayQueue);
static_assert(SIZE > 0, "Size must be positive");
public:
ArrayQueue() = default;
~ArrayQueue() = default;
constexpr size_t capacity() const { return SIZE; }
constexpr bool hasWork() const { return mHead != mTail; }
constexpr bool hasSpace() const { return ((mHead + 1) % SIZE) != mTail; }
constexpr int size() const {
if (mHead > mTail) {
return mHead - mTail;
} else {
return mTail - mHead + SIZE;
}
}
constexpr void push(T&& t) {
int newHead = (mHead + 1) % SIZE;
LOG_ALWAYS_FATAL_IF(newHead == mTail, "no space");
mBuffer[mHead] = std::move(t);
mHead = newHead;
}
constexpr T&& pop() {
LOG_ALWAYS_FATAL_IF(mTail == mHead, "empty");
int index = mTail;
mTail = (mTail + 1) % SIZE;
return std::move(mBuffer[index]);
}
private:
T mBuffer[SIZE];
int mHead = 0;
int mTail = 0;
};
class CommonPool {
PREVENT_COPY_AND_ASSIGN(CommonPool);
public:
using Task = std::function<void()>;
static constexpr auto THREAD_COUNT = 2;
static constexpr auto QUEUE_SIZE = 128;
static void post(Task&& func);
template <class F>
static auto async(F&& func) -> std::future<decltype(func())> {
typedef std::packaged_task<decltype(func())()> task_t;
auto task = std::make_shared<task_t>(std::forward<F>(func));
post([task]() { std::invoke(*task); });
return task->get_future();
}
template <class F>
static auto runSync(F&& func) -> decltype(func()) {
std::packaged_task<decltype(func())()> task{std::forward<F>(func)};
post([&task]() { std::invoke(task); });
return task.get_future().get();
};
private:
CommonPool();
~CommonPool() {}
void enqueue(Task&&);
void workerLoop();
std::mutex mLock;
std::condition_variable mCondition;
int mWaitingThreads = 0;
ArrayQueue<Task, QUEUE_SIZE> mWorkQueue;
};
} // namespace uirenderer
} // namespace android
#endif // FRAMEWORKS_BASE_COMMONPOOL_H