[libcamera-devel] [PATCH 07/18] libcamera: object: Notify objects of thread move

[Jacopo Mondi]

Hi Laurent,

On Mon, Aug 12, 2019 at 03:46:31PM +0300, Laurent Pinchart wrote:
> Send a synchronous message to objects just before they get moved to a
> new thread. This allows the object to perform any required processing.
> EventNotifier and Timer objects will use this mechanism to move
> themselves to the new thread's event disaptcher.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  include/libcamera/object.h      |  3 +++
>  src/libcamera/include/message.h |  1 +
>  src/libcamera/message.cpp       |  2 ++
>  src/libcamera/object.cpp        | 26 ++++++++++++++++++++++++++
>  4 files changed, 32 insertions(+)
>
> diff --git a/include/libcamera/object.h b/include/libcamera/object.h
> index 869200a57d8c..14b939a9bd3d 100644
> --- a/include/libcamera/object.h
> +++ b/include/libcamera/object.h
> @@ -27,6 +27,7 @@ public:
>  	virtual ~Object();
>
>  	void postMessage(std::unique_ptr<Message> msg);
> +	void sendMessage(Message *msg);
>
>  	template<typename T, typename... Args, typename std::enable_if<std::is_base_of<Object, T>::value>::type * = nullptr>
>  	void invokeMethod(void (T::*func)(Args...), Args... args)
> @@ -52,6 +53,8 @@ private:
>
>  	void invokeMethod(BoundMethodBase *method, void *pack);
>
> +	void notifyThreadMove();
> +
>  	void connect(SignalBase *signal);
>  	void disconnect(SignalBase *signal);
>
> diff --git a/src/libcamera/include/message.h b/src/libcamera/include/message.h
> index 92717e316cc3..1cfde5669ede 100644
> --- a/src/libcamera/include/message.h
> +++ b/src/libcamera/include/message.h
> @@ -23,6 +23,7 @@ public:
>  	enum Type {
>  		None = 0,
>  		InvokeMessage = 1,
> +		ThreadMoveMessage = 2,
>  		UserMessage = 1000,
>  	};
>
> diff --git a/src/libcamera/message.cpp b/src/libcamera/message.cpp
> index f6c39d40fc73..efafb655c17e 100644
> --- a/src/libcamera/message.cpp
> +++ b/src/libcamera/message.cpp
> @@ -47,6 +47,8 @@ std::atomic_uint Message::nextUserType_{ Message::UserMessage };
>   * \brief Invalid message type
>   * \var Message::InvokeMessage
>   * \brief Asynchronous method invocation across threads
> + * \var Message::ThreadMoveMessage
> + * \brief Object is being moved to a different thread
>   * \var Message::UserMessage
>   * \brief First value available for user-defined messages
>   */
> diff --git a/src/libcamera/object.cpp b/src/libcamera/object.cpp
> index 7d70ce21b5d0..7c68ec01f78c 100644
> --- a/src/libcamera/object.cpp
> +++ b/src/libcamera/object.cpp
> @@ -74,6 +74,20 @@ void Object::postMessage(std::unique_ptr<Message> msg)
>  	thread()->postMessage(std::move(msg), this);
>  }
>
> +/**
> + * \brief Send a message directly to the object
> + * \param[in] msg The message
> + *
> + * This method sends the message \a msg directly to the object, delivering it
> + * synchronously through the message() method in the current thread. Message
> + * ownership is not passed to the method, and the caller shall delete the
> + * message after this call.
> + */
> +void Object::sendMessage(Message *msg)
> +{
> +	message(msg);
> +}
> +
>  /**
>   * \brief Message handler for the object
>   * \param[in] msg The message
> @@ -135,6 +149,10 @@ void Object::invokeMethod(BoundMethodBase *method, void *args)
>   * This method moves the object from the current thread to the new \a thread.
>   * It shall be called from the thread in which the object currently lives,
>   * otherwise the behaviour is undefined.
> + *
> + * Before the object is moved, a Message::ThreadMoveMessage message is sent to
> + * it. The message() method can be reimplement in derived classes to be notified
> + * of the upcoming thread move and perform any required processing.
>   */
>  void Object::moveToThread(Thread *thread)
>  {
> @@ -143,9 +161,17 @@ void Object::moveToThread(Thread *thread)
>  	if (thread_ == thread)
>  		return;
>
> +	notifyThreadMove();
> +
>  	thread->moveObject(this);
>  }
>
> +void Object::notifyThreadMove()
> +{
> +	Message msg(Message::ThreadMoveMessage);
> +	sendMessage(&msg);

I missed why you can't call message(&msg) directly here.

> +}
> +
>  void Object::connect(SignalBase *signal)
>  {
>  	signals_.push_back(signal);
> --
> Regards,
>
> Laurent Pinchart
>
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel at lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel
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