libcamera: object: Add an asynchronous method invocation method

Add a helper invokeMethod() to the Object class that allows asynchrnous
invocation of any method of an Object instance. Asynchronous invocation
occurs when control returns to the event dispatcher of the target
object's thread, in the context of that thread.

To support this, generalise the SignalMessage implementation to support
automatic deletion of the associated BoundMethod, and rename the message
to InvokeMessage to reflect the more generic purpose.

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

1 files changed, 26 insertions, 3 deletions

diff --git a/src/libcamera/object.cpp b/src/libcamera/object.cpp
index 0adbc203..7d70ce21 100644
--- a/src/libcamera/object.cpp
+++ b/src/libcamera/object.cpp
@@ -12,6 +12,7 @@
 #include "log.h"
 #include "message.h"
 #include "thread.h"
+#include "utils.h"
 
 /**
  * \file object.h
@@ -88,9 +89,9 @@ void Object::postMessage(std::unique_ptr<Message> msg)
 void Object::message(Message *msg)
 {
 	switch (msg->type()) {
-	case Message::SignalMessage: {
-		SignalMessage *smsg = static_cast<SignalMessage *>(msg);
-		smsg->method_->invokePack(smsg->pack_);
+	case Message::InvokeMessage: {
+		InvokeMessage *iMsg = static_cast<InvokeMessage *>(msg);
+		iMsg->invoke();
 		break;
 	}
 
@@ -100,6 +101,28 @@ void Object::message(Message *msg)
 }
 
 /**
+ * \fn void Object::invokeMethod(void (T::*func)(Args...), Args... args)
+ * \brief Invoke a method asynchronously on an Object instance
+ * \param[in] func The object method to invoke
+ * \param[in] args The method arguments
+ *
+ * This method invokes the member method \a func when control returns to the
+ * event loop of the object's thread. The method is executed in the object's
+ * thread with arguments \a args.
+ *
+ * Arguments \a args passed by value or reference are copied, while pointers
+ * are passed untouched. The caller shall ensure that any pointer argument
+ * remains valid until the method is invoked.
+ */
+
+void Object::invokeMethod(BoundMethodBase *method, void *args)
+{
+	std::unique_ptr<Message> msg =
+		utils::make_unique<InvokeMessage>(method, args, true);
+	postMessage(std::move(msg));
+}
+
+/**
  * \fn Object::thread()
  * \brief Retrieve the thread the object is bound to
  * \return The thread the object is bound to