[libcamera-devel] [PATCH 2/2] libcamera: message: Add user message types

[Jacopo Mondi]

On Mon, Jul 15, 2019 at 12:29:39PM +0300, Laurent Pinchart wrote:
> From: Jacopo Mondi <jacopo at jmondi.org>
>
> Reserve identifiers for user-defined message types and add an operation
> to the Message class to create register the type identifiers.

create 'and' register ?

Otherwise
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
   j

>
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> Changes since v1:
>
> - Replace mutex with atomic
> - Rework documentation
> - Rename registerUserMessageType() to registerMessageType()
> - Extend the Message test
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/libcamera/include/message.h |  7 +++++++
>  src/libcamera/message.cpp       | 36 +++++++++++++++++++++++++++++++++
>  test/message.cpp                | 11 ++++++++++
>  3 files changed, 54 insertions(+)
>
> diff --git a/src/libcamera/include/message.h b/src/libcamera/include/message.h
> index db17d647c280..416fe74b10ad 100644
> --- a/src/libcamera/include/message.h
> +++ b/src/libcamera/include/message.h
> @@ -7,6 +7,8 @@
>  #ifndef __LIBCAMERA_MESSAGE_H__
>  #define __LIBCAMERA_MESSAGE_H__
>
> +#include <atomic>
> +
>  namespace libcamera {
>
>  class Object;
> @@ -19,6 +21,7 @@ public:
>  	enum Type {
>  		None = 0,
>  		SignalMessage = 1,
> +		UserMessage = 1000,
>  	};
>
>  	Message(Type type);
> @@ -27,11 +30,15 @@ public:
>  	Type type() const { return type_; }
>  	Object *receiver() const { return receiver_; }
>
> +	static Type registerMessageType();
> +
>  private:
>  	friend class Thread;
>
>  	Type type_;
>  	Object *receiver_;
> +
> +	static std::atomic_uint nextUserType_;
>  };
>
>  class SignalMessage : public Message
> diff --git a/src/libcamera/message.cpp b/src/libcamera/message.cpp
> index 9f22ad7fc0b0..d44d2a4c73a8 100644
> --- a/src/libcamera/message.cpp
> +++ b/src/libcamera/message.cpp
> @@ -31,6 +31,8 @@ namespace libcamera {
>
>  LOG_DEFINE_CATEGORY(Message)
>
> +std::atomic_uint Message::nextUserType_{ Message::UserMessage };
> +
>  /**
>   * \class Message
>   * \brief A message that can be posted to a Thread
> @@ -43,6 +45,8 @@ LOG_DEFINE_CATEGORY(Message)
>   * \brief Invalid message type
>   * \var Message::SignalMessage
>   * \brief Asynchronous signal delivery across threads
> + * \var Message::UserMessage
> + * \brief First value available for user-defined messages
>   */
>
>  /**
> @@ -70,6 +74,38 @@ Message::~Message()
>   * \return The message receiver
>   */
>
> +/**
> + * \brief Reserve and register a custom user-defined message type
> + *
> + * Custom message types use values starting at Message::UserMessage. Assigning
> + * custom types manually may lead to accidental duplicated types. To avoid this
> + * problem, this method reserves and returns the next available user-defined
> + * message type.
> + *
> + * The recommended way to use this method is to subclass Message and provide a
> + * static accessor for the custom message type.
> + *
> + * \code{.cpp}
> + * class MyCustomMessage : public Message
> + * {
> + * public:
> + *	MyCustomMessage() : Message(type()) { }
> + *
> + *	static Message::Type type()
> + *	{
> + *		static MessageType type = registerMessageType();
> + *		return type;
> + *	}
> + * };
> + * \endcode
> + *
> + * \return A new unique message type
> + */
> +Message::Type Message::registerMessageType()
> +{
> +	return static_cast<Message::Type>(nextUserType_++);
> +}
> +
>  /**
>   * \class SignalMessage
>   * \brief A message carrying a Signal across threads
> diff --git a/test/message.cpp b/test/message.cpp
> index de98da3e8754..3775c30a20b3 100644
> --- a/test/message.cpp
> +++ b/test/message.cpp
> @@ -52,6 +52,17 @@ class MessageTest : public Test
>  protected:
>  	int run()
>  	{
> +		Message::Type msgType[2] = {
> +			Message::registerMessageType(),
> +			Message::registerMessageType(),
> +		};
> +
> +		if (msgType[0] != Message::UserMessage ||
> +		    msgType[1] != Message::UserMessage + 1) {
> +			cout << "Failed to register message types" << endl;
> +			return TestFail;
> +		}
> +
>  		MessageReceiver receiver;
>  		receiver.moveToThread(&thread_);
>
> --
> Regards,
>
> Laurent Pinchart
>
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel at lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel
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