89 lines
2.3 KiB
C++
89 lines
2.3 KiB
C++
/*
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* Copyright (C) 2020 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 <condition_variable>
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#include <functional>
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#include <memory>
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#include <vector>
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#include "common/libs/concurrency/semaphore.h"
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#include "common/libs/concurrency/thread_safe_queue.h"
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namespace cuttlefish {
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template <typename T, typename Queue>
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class Multiplexer {
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public:
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using QueuePtr = std::unique_ptr<Queue>;
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using QueueSelector = std::function<int(void)>;
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template <typename... Args>
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static QueuePtr CreateQueue(Args&&... args) {
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auto raw_ptr = new Queue(std::forward<Args>(args)...);
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return QueuePtr(raw_ptr);
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}
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Multiplexer() : sem_items_{0} {}
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int RegisterQueue(QueuePtr&& queue) {
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const int id_to_return = queues_.size();
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queues_.push_back(std::move(queue));
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return id_to_return;
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}
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void Push(const int idx, T&& t) {
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CheckIdx(idx);
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queues_[idx]->Push(std::move(t));
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sem_items_.SemPost();
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}
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T Pop(QueueSelector selector) {
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SemWait();
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int q_id = selector();
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CheckIdx(q_id); // check, if weird, will die there
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QueuePtr& queue = queues_[q_id];
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CHECK(queue) << "queue must not be null.";
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return queue->Pop();
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}
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T Pop() {
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auto default_selector = [this]() -> int {
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for (int i = 0; i < queues_.size(); i++) {
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if (!queues_[i]->IsEmpty()) {
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return i;
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}
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}
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return -1;
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};
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return Pop(default_selector);
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}
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bool IsEmpty(const int idx) { return queues_[idx]->IsEmpty(); }
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void SemWait() { sem_items_.SemWait(); }
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private:
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void CheckIdx(const int idx) {
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CHECK(idx >= 0 && idx < queues_.size()) << "queues_ array out of bound";
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}
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// total items across the queues
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Semaphore sem_items_;
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std::vector<QueuePtr> queues_;
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QueuePtr null_ptr_;
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};
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} // end of namespace cuttlefish
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