boost::capy::async_mutex

An asynchronous mutex for coroutines.

Synopsis

Declared in <boost/capy/ex/async_mutex.hpp>

class async_mutex;

Description

This mutex provides mutual exclusion for coroutines without blocking. When a coroutine attempts to acquire a locked mutex, it suspends and is added to an intrusive wait queue. When the holder unlocks, the next waiter is resumed with the lock held.

Zero Allocation

The wait queue node is embedded in the lock_awaiter, which lives on the coroutine frame during suspension. No heap allocation occurs.

Thread Safety

This mutex is NOT thread‐safe. It is designed for single‐threaded use where multiple coroutines may contend for a resource.

Example

async_mutex mutex;

task<> protected_operation() {
    co_await mutex.lock();
    // ... critical section ...
    mutex.unlock();
}

// Or with RAII:
task<> protected_operation() {
    auto guard = co_await mutex.scoped_lock();
    // ... critical section ...
    // unlocks automatically
}