# asio-mutex

**Repository Path**: ruinco/asio-mutex

## Basic Information

- **Project Name**: asio-mutex
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2025-10-08
- **Last Updated**: 2025-10-08

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

<!--
SPDX-FileCopyrightText: 2023 Daniel Vrátil <daniel.vratil@gendigital.com>

SPDX-License-Identifier: BSL-1.0
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# Async Mutex for Boost Asio

This repository contains an implementation of an asynchronous mutex for Boos Asio. Asynchronous 
here means that the locking operation can be `co_await`ed, thus avoiding potential deadlocks 
in multithreaded coroutine code.

*Credits*: the implementation of the mutex itself is heavily inspired by Lewis Bakers's `async_mutex`
from [cppcoro](https://github.com/lewissbaker/cppcoro/), published under the MIT license.

## Dependencies

* Boost >= 1.80.0 - for obvious reasons
* Doxygen - optional, use `make doc` to generate doxygen documentation (in build/doc/html)
* Catch2 - optional, use `make check` or `make checkVerbose` to run tests

## CMake Options

* `-DENABLE_TESTING=ON|OFF` - default `ON`, set to off to not build tests
* `-DSANITIZER=asan|tsan|ubsan|msan` - default empty, set to one of the values to build with the given sanitizer

## API

```cpp
namespace avast::asio {

/**
 * A basic mutex that can acquire lock asynchronously using coroutines.
 **/
class async_mutex {
public:
    /**
     * Constructs a new, unlocked mutex.
     **/
    explicit async_mutex() noexcept;

    /**
     * Destroys the mutex.
     *
     * The mutex must be in unlocked state, otherwise the behavior is undefined.
     **/
    ~async_mutex();

    /**
     * Attempts to acquire a lock without blocking.
     *
     * Returns `true` if lock has been acquired successfuly, `false` otherwise.
     **/
    bool try_lock();

    /**
     * Asynchronously acquires a lock.
     *
     * When the returned awaitable is `co_await`ed it initiates the process
     * of acquiring a lock. The awaiter is suspended. Once the lock is acquired
     * (which can be immediately if nothing else holds the lock currently) the
     * awaiter is resumed and is now holding the lock.
     *
     * It's awaiter's responsibility to release the lock by calling `unlock()`.
     **/
    boost::asio::awaitable<> async_lock(LockToken);

    /**
     * Asynchronously acquires a lock and returns a scoped lock.
     *
     * Behaves exactly like `async_lock()`, except that the result of `co_await`ing the
     * returned awaitable is a scoped lock object, which will automatically release the
     * lock when destroyed.
     **/
    boost::asio::awaitable<avast::asio::async_mutex_lock> async_scoped_lock(LockToken);


    /**
     * Unlocks the mutex.
     *
     * Calling this method on an unlocked mutex is undefined behavior.
     **/
    void unlock();
};

/**
 * A RAII-style lock for async_mutex which automatically unlocks the mutex when destroyed.
 **/
class async_mutex_lock {
public:
    /**
     * Constructs a new async_mutex_lock, taking ownership of the `mutex`.
     *
     * The mutex must be in a locked state.
     **/
    explicit async_mutex_lock(async_mutex &mutex, std::adopt_lock_t) noexcept;

    async_mutex_lock(async_mutex_lock &&) noexcept;

    async_mutex_lock(const async_mutex_lock &) = delete;
    async_mutex_lock &operator=(const async_mutex_lock &) = delete;

    /**
     * Unlocks the held mutex and destroys the lock.
     **/
    ~async_mutex_lock();
};
```

## Authors

* Daniel Vrátil <daniel.vratil@gendigital.com>
* Martin Beran <martin.beran@gendigital.com>

## License

All code is licensed under Boost Software License 1.0

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