LivoxProto1: Document UDP demuxer purpose & use cases

Also fix bug in transient resource transfer from continuation
to Device object.

commonLibs/livoxProto1/device.cpp

@@ -1714,13 +1714,13 @@ private:
 		// Transfer ownership of the socket from temporary to main descriptor
 		if (tmpPcloudEnableFdDesc.is_open())
 		{
+			// Close the temporary descriptor (but don't close the fd)
 			int fd = tmpPcloudEnableFdDesc.native_handle();
+			tmpPcloudEnableFdDesc.release();
+			// Give the transient FD to the Device object.
 			device.pcloudDataSocketDesc =
 				std::make_unique<boost::asio::posix::stream_descriptor>(
 					device.componentThread->getIoService(), fd);
-
-			// Close the temporary descriptor (but don't close the fd)
-			tmpPcloudEnableFdDesc.release();
 		}
 		device.pcloudDataActive.store(true);
 	}
@@ -1888,6 +1888,14 @@ void Device::registerUdpCommandHandler(
 	const std::string& deviceIP
 	)
 {
+	/**		EXPLANATION:
+	 * Register a UDP command handler for the given cmd_set and cmd_id.
+	 * If the handler already exists for the given device IP, replace it.
+	 * If the handler does not exist, add it to the temporary collection.
+	 *
+	 * Adding a handler to a cmd_set+cmd_id pair which already has a handler
+	 * results in the new handler replacing the old one.
+	 */
 	auto key = std::make_pair(cmd_set, cmd_id);
 	udpCommandHandlers[key] = handler; // Don't move, we need to copy