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MPMCQueue

LibXR::MPMCQueue<T> is the current public bounded multi-producer / multi-consumer queue in mainline LibXR.

Compared with SPSCQueue, it is intended for more general concurrent topologies:

  • multiple contexts may push;
  • multiple contexts may pop;
  • capacity is fixed;
  • payloads are moved as byte blocks.

Basic Usage​

LibXR::MPMCQueue<uint16_t> queue(32);

queue.Push(100);

uint16_t value = 0;
queue.Pop(value);

Payload Requirements​

Current mainline places explicit restrictions on MPMCQueue<T>:

  • T must be trivially copyable;
  • T must be trivially destructible.

This follows from the implementation strategy: the queue moves payloads as raw byte blocks and does not manage complex object lifetime internally.

Typical Use Cases​

Good fit:

  • shared TX queues with multiple producers;
  • public concurrent queues accessed by interrupts and threads, or by multiple threads;
  • internal driver queues that need bounded concurrent behavior.

In current mainline, several CAN TX queue implementations already use MPMCQueue<ClassicPack> or similar payloads.

How to Choose Between SPSCQueue and MPMCQueue​

Do not treat MPMCQueue as the default replacement for every queue. The current codebase is moving toward topology-driven selection:

  • exactly one producer and one consumer: prefer SPSCQueue;
  • actual multiple producers or consumers: use MPMCQueue.

This keeps the producer/consumer topology explicit.