multi_loop.h File Reference

Multi-threaded event loop backed by a pool of worker threads sharing one task queue. More...

#include <memory>
#include "./message_loop.h"

Include dependency graph for multi_loop.h:

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Classes
class	vlink::MultiLoop
	Multi-threaded variant of MessageLoop running tasks on a worker-thread pool. More...

Namespaces
namespace	vlink

Detailed Description

Multi-threaded event loop backed by a pool of worker threads sharing one task queue.

MultiLoop extends MessageLoop by running thread_num worker threads that all dequeue and execute tasks from the same queue. This enables parallel task execution without changing the posting API: callers still call post_task() and exec_task() exactly as with a single-threaded MessageLoop.

Differences from MessageLoop:

• Tasks may run concurrently on multiple threads; they are not serialised.
• is_in_same_thread() returns true if the caller is any of the worker threads.
• on_begin() and on_end() are called once per worker thread.
• on_task_changed() is called from the executing worker thread.

Note

• Shared state accessed inside task callbacks must be protected by its own synchronisation.
• Timers attached to a MultiLoop still fire on one of the worker threads (non-deterministic).
• The destructor waits for all worker threads to finish.

Example

vlink::MultiLoop loop(4);  // 4 worker threads
loop.async_run();
 
for (int i = 0; i < 100; ++i) {
  loop.post_task([i]() { process(i); });
}
 
loop.wait_for_idle();
loop.quit();