libcamera: thread: Add a messaging passing API

Create a new Message class to model a message that can be passed to an
object living in another thread. Only an invalid message type is
currently defined, more messages will be added in the future.

The Thread class is extended with a messages queue, and the Object class
with thread affinity.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/libcamera/object.h b/include/libcamera/object.h
index eadd41f9..d61dfb1e 100644
--- a/include/libcamera/object.h
+++ b/include/libcamera/object.h
@@ -8,26 +8,39 @@
 #define __LIBCAMERA_OBJECT_H__
 
 #include <list>
+#include <memory>
 
 namespace libcamera {
 
+class Message;
 class SignalBase;
 template<typename... Args>
 class Signal;
+class Thread;
 
 class Object
 {
 public:
+	Object();
 	virtual ~Object();
 
+	void postMessage(std::unique_ptr<Message> msg);
+	virtual void message(Message *msg);
+
+	Thread *thread() const { return thread_; }
+	void moveToThread(Thread *thread);
+
 private:
 	template<typename... Args>
 	friend class Signal;
+	friend class Thread;
 
 	void connect(SignalBase *signal);
 	void disconnect(SignalBase *signal);
 
+	Thread *thread_;
 	std::list<SignalBase *> signals_;
+	unsigned int pendingMessages_;
 };
 
 }; /* namespace libcamera */