[libcamera-devel] [PATCH v2 1/3] libcamera: thread: Support selective message dispatch to thread

[Umang Jain]

Extend the current dispatchMessages() to support dispatching of
selective messsages according to the Message::Type passed in
the function argument. dispatchMessages() can now be called
explicitly to force deliver selected type's message to the
thread for processing (typically when event loop is not
running).

Add a helper Message::Type::CatchAll message type to deliver every
message posted to the thread.

Signed-off-by: Umang Jain <email at uajain.com>
---
 include/libcamera/internal/message.h    |  1 +
 include/libcamera/internal/thread.h     |  3 +-
 src/libcamera/event_dispatcher_poll.cpp |  2 +-
 src/libcamera/message.cpp               |  2 ++
 src/libcamera/thread.cpp                | 47 ++++++++++++++++++-------
 5 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/include/libcamera/internal/message.h b/include/libcamera/internal/message.h
index 92ea64a..b8d9866 100644
--- a/include/libcamera/internal/message.h
+++ b/include/libcamera/internal/message.h
@@ -25,6 +25,7 @@ public:
 		None = 0,
 		InvokeMessage = 1,
 		ThreadMoveMessage = 2,
+		CatchAll = 999,
 		UserMessage = 1000,
 	};
 
diff --git a/include/libcamera/internal/thread.h b/include/libcamera/internal/thread.h
index 7b59e58..1dfeb72 100644
--- a/include/libcamera/internal/thread.h
+++ b/include/libcamera/internal/thread.h
@@ -14,6 +14,7 @@
 
 #include <libcamera/signal.h>
 
+#include "libcamera/internal/message.h"
 #include "libcamera/internal/utils.h"
 
 namespace libcamera {
@@ -47,7 +48,7 @@ public:
 	EventDispatcher *eventDispatcher();
 	void setEventDispatcher(std::unique_ptr<EventDispatcher> dispatcher);
 
-	void dispatchMessages();
+	void dispatchMessages(Message::Type type);
 
 protected:
 	int exec();
diff --git a/src/libcamera/event_dispatcher_poll.cpp b/src/libcamera/event_dispatcher_poll.cpp
index 9ab85da..b9fabf8 100644
--- a/src/libcamera/event_dispatcher_poll.cpp
+++ b/src/libcamera/event_dispatcher_poll.cpp
@@ -146,7 +146,7 @@ void EventDispatcherPoll::processEvents()
 {
 	int ret;
 
-	Thread::current()->dispatchMessages();
+	Thread::current()->dispatchMessages(Message::Type::CatchAll);
 
 	/* Create the pollfd array. */
 	std::vector<struct pollfd> pollfds;
diff --git a/src/libcamera/message.cpp b/src/libcamera/message.cpp
index e9b3e73..e462f90 100644
--- a/src/libcamera/message.cpp
+++ b/src/libcamera/message.cpp
@@ -49,6 +49,8 @@ std::atomic_uint Message::nextUserType_{ Message::UserMessage };
  * \brief Asynchronous method invocation across threads
  * \var Message::ThreadMoveMessage
  * \brief Object is being moved to a different thread
+ * \var Message::CatchAll
+ * \brief Helper to match message of any type
  * \var Message::UserMessage
  * \brief First value available for user-defined messages
  */
diff --git a/src/libcamera/thread.cpp b/src/libcamera/thread.cpp
index d1750d7..d3a5f81 100644
--- a/src/libcamera/thread.cpp
+++ b/src/libcamera/thread.cpp
@@ -552,26 +552,47 @@ void Thread::removeMessages(Object *receiver)
 }
 
 /**
- * \brief Dispatch all posted messages for this thread
+ * \brief Dispatch posted messages for this thread as per \a type Message::Type.
+ *  Pass Message::Type::CatchAll to dispatch every posted message posted for
+ *  this thread.
  */
-void Thread::dispatchMessages()
+void Thread::dispatchMessages(Message::Type type)
 {
 	MutexLocker locker(data_->messages_.mutex_);
 
-	while (!data_->messages_.list_.empty()) {
-		std::unique_ptr<Message> msg = std::move(data_->messages_.list_.front());
-		data_->messages_.list_.pop_front();
-		if (!msg)
-			continue;
+	if (type == Message::Type::CatchAll) {
+		while (!data_->messages_.list_.empty()) {
+			std::unique_ptr<Message> msg =
+				std::move(data_->messages_.list_.front());
+			data_->messages_.list_.pop_front();
+			if (!msg)
+				continue;
 
-		Object *receiver = msg->receiver_;
-		ASSERT(data_ == receiver->thread()->data_);
+			Object *receiver = msg->receiver_;
+			ASSERT(data_ == receiver->thread()->data_);
 
-		receiver->pendingMessages_--;
+			receiver->pendingMessages_--;
 
-		locker.unlock();
-		receiver->message(msg.get());
-		locker.lock();
+			locker.unlock();
+			receiver->message(msg.get());
+			locker.lock();
+		}
+	} else {
+		for (std::unique_ptr<Message> &msg : data_->messages_.list_) {
+			if (!msg)
+				continue;
+
+			if (msg->type() == type) {
+				std::unique_ptr<Message> message = std::move(msg);
+				Object *receiver = message->receiver_;
+				ASSERT(data_ == receiver->thread()->data_);
+				receiver->pendingMessages_--;
+
+				locker.unlock();
+				receiver->message(message.get());
+				locker.lock();
+			}
+		}
 	}
 }
 
-- 
2.26.2