SPSCQueue 是用 C++ 11 編寫的單個生產者單一消費者等待和無鎖定大小隊列。

示例代碼

SPSCQueue q(2);
auto t = std::thread([&] {
  while (!q.front());
  std::cout << *q.front() << std::endl;
  q.pop();
});
q.push(1);
t.join();

使用

• SPSCQueue(size_t capacity);

  Create a?SPSCqueue?holding items of type?T?with capacity?capacity. Capacity need to be greater than 2.

• void emplace(Args &&... args);

  Enqueue an item using inplace construction. Blocks if queue is full.

• bool try_emplace(Args &&... args);

  Try to enqueue an item using inplace construction. Returns?true?on success and?false?if queue is full.

• void push(const T &v);

  Enqueue an item using copy construction. Blocks if queue is full.

• template void push(P &&v);

  Enqueue an item using move construction. Participates in overload resolution only if?std::is_constructible::value == true. Blocks if queue is full.

• bool try_push(const T &v);

  Try to enqueue an item using copy construction. Returns?true?on success and?false?if queue is full.

• template void try_push(P &&v);

  Try to enqueue an item using move construction. Returns?true?on success and?false?if queue is full. Participates in overload resolution only if?std::is_constructible::value == true.

• T *front();

  Return pointer to front of queue. Returns?nullptr?if queue is empty.

• pop();

  Dequeue first elment of queue. Invalid to call if queue is empty. Requires?std::is_nothrow_destructible::value == true.

一旦一個單一的寫線程可以執行入隊列的操作時，只有一個單一的讀線程可以執行取隊列操作，其他的使用都是不允許的。

實現原理

底層實現是一個環形緩沖區。

參考資料:

• Intel.?Avoiding and Identifying False Sharing Among Threads.
• Wikipedia.?Ring buffer.
• Wikipedia.?False sharing.

性能測試

以下測試結果是基于?2 socket machine with 2 x Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz.