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97 lines
2.0 KiB
C++
97 lines
2.0 KiB
C++
// ©2013-2014 Cameron Desrochers.
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// Distributed under the simplified BSD license (see the LICENSE file that
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// should have come with this file).
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#pragma once
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#include "wrappers.h"
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#include <mutex>
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// Naïve implementation of a simple lock-based queue. A std::mutex is obtained for every
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// method. Note that while the queue size is not fixed, each enqueue operation allocates
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// memory, and each dequeue frees memory.
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template<typename T>
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class LockBasedQueue
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{
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public:
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typedef DummyToken producer_token_t;
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typedef DummyToken consumer_token_t;
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public:
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LockBasedQueue()
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{
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tail = nullptr;
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head = nullptr;
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}
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~LockBasedQueue()
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{
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while (head != nullptr) {
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Node* next = head->next;
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delete head;
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head = next;
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}
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}
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template<typename U>
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inline bool enqueue(U&& item)
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{
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Node* node = new Node(item);
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std::lock_guard<std::mutex> guard(mutex);
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if (tail == nullptr) {
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head = tail = node;
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}
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else {
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tail->next = node;
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tail = node;
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}
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return true;
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}
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inline bool try_dequeue(T& item)
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{
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std::lock_guard<std::mutex> guard(mutex);
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if (head == nullptr) {
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return false;
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}
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else {
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item = std::move(head->item);
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Node* next = head->next;
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delete head;
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head = next;
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if (head == nullptr) {
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tail = nullptr;
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}
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return true;
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}
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}
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// Dummy token methods (not used)
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bool enqueue(producer_token_t const&, T const&) { return false; }
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bool try_enqueue(producer_token_t, T const&) { return false; }
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bool try_dequeue(consumer_token_t, T& item) { return false; }
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template<typename It> bool enqueue_bulk(It, size_t) { return false; }
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template<typename It> bool enqueue_bulk(producer_token_t const&, It, size_t) { return false; }
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template<typename It> size_t try_dequeue_bulk(It, size_t) { return 0; }
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template<typename It> size_t try_dequeue_bulk(consumer_token_t, It, size_t) { return 0; }
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private:
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struct Node
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{
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T item;
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Node* next;
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template<typename U>
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Node(U&& item)
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: item(std::forward<U>(item)), next(nullptr)
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{
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}
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};
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std::mutex mutex;
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Node* head;
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Node* tail;
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};
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