libcamera: thread: Support selective message dispatch to thread

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@uajain.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

2 files changed, 28 insertions, 10 deletions

diff --git a/include/libcamera/internal/thread.h b/include/libcamera/internal/thread.h
index 7b59e583..f6367a8f 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 d1750d72..87006a9c 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();
 	}
 }