[iron] Make rosbag2_transport::Player::play() run in a separate thread (backport #1503)

rosbag2_py/src/rosbag2_py/_transport.cpp

@@ -155,6 +155,7 @@ class Player
         exec.spin();
       });
     player->play();
+    player->wait_for_playback_to_finish();
 
     exec.cancel();
     spin_thread.join();
@@ -175,15 +176,11 @@ class Player
       [&exec]() {
         exec.spin();
       });
-    auto play_thread = std::thread(
-      [&player]() {
-        player->play();
-      });
+    player->play();
     player->burst(num_messages);
 
     exec.cancel();
     spin_thread.join();
-    play_thread.join();
   }
 };
 

rosbag2_transport/include/rosbag2_transport/player.hpp

@@ -20,7 +20,6 @@
 #include <functional>
 #include <future>
 #include <memory>
-#include <queue>
 #include <string>
 #include <unordered_map>
 #include <utility>
@@ -110,9 +109,19 @@ class Player : public rclcpp::Node
   ROSBAG2_TRANSPORT_PUBLIC
   virtual ~Player();
 
+  /// \brief Start playback asynchronously in a separate thread
+  /// \return false if playback thread already running, otherwise true
   ROSBAG2_TRANSPORT_PUBLIC
   bool play();
 
+  /// \brief Waits on the condition variable until the play thread finishes.
+  /// @param timeout Maximum time in the fraction of seconds to wait for player to finish.
+  /// If timeout is negative, the wait_for_playback_to_finish will be a blocking call.
+  /// @return true if playback finished during timeout, otherwise false.
+  ROSBAG2_TRANSPORT_PUBLIC
+  bool wait_for_playback_to_finish(
+    std::chrono::duration<double> timeout = std::chrono::seconds(-1));
+
   /// \brief Unpause if in pause mode, stop playback and exit from play.
   ROSBAG2_TRANSPORT_PUBLIC
   void stop();