[libcamera-devel] [PATCH v4 1/4] 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).

Signed-off-by: Umang Jain <email at uajain.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 include/libcamera/internal/thread.h |  3 ++-
 src/libcamera/thread.cpp            | 35 +++++++++++++++++++++--------
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/include/libcamera/internal/thread.h b/include/libcamera/internal/thread.h
index 7b59e58..f6367a8 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 = Message::Type::None);
 
 protected:
 	int exec();
diff --git a/src/libcamera/thread.cpp b/src/libcamera/thread.cpp
index d1750d7..87006a9 100644
--- a/src/libcamera/thread.cpp
+++ b/src/libcamera/thread.cpp
@@ -552,25 +552,42 @@ void Thread::removeMessages(Object *receiver)
 }
 
 /**
- * \brief Dispatch all posted messages for this thread
+ * \brief Dispatch posted messages for this thread
+ * \param[in] type The message type
+ *
+ * This function immediately dispatches all the messages previously posted for
+ * this thread with postMessage() that match the message \a type. If the \a type
+ * is Message::Type::None, all messages are dispatched.
  */
-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)
+	std::list<std::unique_ptr<Message>> &messages = data_->messages_.list_;
+
+	for (auto iter = messages.begin(); iter != messages.end(); ) {
+		std::unique_ptr<Message> &msg = *iter;
+
+		if (!msg) {
+			iter = data_->messages_.list_.erase(iter);
+			continue;
+		}
+
+		if (type != Message::Type::None && msg->type() != type) {
+			++iter;
 			continue;
+		}
 
-		Object *receiver = msg->receiver_;
-		ASSERT(data_ == receiver->thread()->data_);
+		std::unique_ptr<Message> message = std::move(msg);
+		iter = data_->messages_.list_.erase(iter);
 
+		Object *receiver = message->receiver_;
+		ASSERT(data_ == receiver->thread()->data_);
 		receiver->pendingMessages_--;
 
 		locker.unlock();
-		receiver->message(msg.get());
+		receiver->message(message.get());
+		message.reset();
 		locker.lock();
 	}
 }
-- 
2.26.2