[libcamera-devel] [PATCH 1/4] libcamera: thread: Document dispatchMessages() thread-safety requirements

[Umang Jain]

Hi Laurent

Thanks for the patch

On 5/23/21 8:01 AM, Laurent Pinchart wrote:
> The Thread class is incorrectly documented as thread-safe, as the
> dispatchMessages() function isn't thread-safe. Fix the documentation by
> tagging individual functions as thread-safe as appropriate.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
>   src/libcamera/thread.cpp | 17 +++++++++++++++--
>   1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/src/libcamera/thread.cpp b/src/libcamera/thread.cpp
> index 198670de33a2..285b808332e8 100644
> --- a/src/libcamera/thread.cpp
> +++ b/src/libcamera/thread.cpp
> @@ -229,8 +229,6 @@ ThreadData *ThreadData::current()
>    * called. The event loop dispatches events (messages, notifiers and timers)
>    * sent to the objects living in the thread. This behaviour can be modified by
>    * overriding the run() function.
> - *
> - * \context This class is \threadsafe.
>    */
>   
>   /**
> @@ -361,6 +359,8 @@ void Thread::finishThread()
>    *
>    * Calling exit() on a thread that reimplements the run() method and doesn't
>    * call exec() will likely have no effect.
> + *
> + * \context This function is \threadsafe.
>    */
>   void Thread::exit(int code)
>   {
> @@ -383,6 +383,8 @@ void Thread::exit(int code)
>    * utils::duration::max(), the wait never times out. If the thread is not
>    * running the function returns immediately.
>    *
> + * \context This function is \threadsafe.
> + *
>    * \return True if the thread has finished, or false if the wait timed out
>    */
>   bool Thread::wait(utils::duration duration)
> @@ -412,6 +414,8 @@ bool Thread::wait(utils::duration duration)
>    * started. This method guarantees that it returns true after the start()
>    * method returns, and false after the wait() method returns.
>    *
> + * \context This function is \threadsafe.
> + *
>    * \return True if the thread is running, false otherwise
>    */
>   bool Thread::isRunning()
> @@ -427,6 +431,7 @@ bool Thread::isRunning()
>   
>   /**
>    * \brief Retrieve the Thread instance for the current thread
> + * \context This function is \threadsafe.
>    * \return The Thread instance for the current thread
>    */
>   Thread *Thread::current()
> @@ -441,6 +446,8 @@ Thread *Thread::current()
>    * The thread ID corresponds to the Linux thread ID (TID) as returned by the
>    * gettid system call.
>    *
> + * \context This function is \threadsafe.
> + *
>    * \return The ID of the current thread
>    */
>   pid_t Thread::currentId()
> @@ -455,6 +462,8 @@ pid_t Thread::currentId()
>    * This function retrieves the internal event dispatcher for the thread. The
>    * returned event dispatcher is valid until the thread is destroyed.
>    *
> + * \context This function is \threadsafe.
> + *
>    * \return Pointer to the event dispatcher
>    */
>   EventDispatcher *Thread::eventDispatcher()
> @@ -544,6 +553,10 @@ void Thread::removeMessages(Object *receiver)
>    * This function immediately dispatches all the messages previously posted for
>    * this thread with postMessage() that match the message \a type. If the \a type
>    * is Message::Type::None, all messages are dispatched.
> + *
> + * Messages shall only be dispatched from the current thread, typically within
> + * the thread from the run() function. Calling this function outside of the
> + * thread results in undefined behaviour.
>    */
>   void Thread::dispatchMessages(Message::Type type)
>   {