[Backport/Humble] Notification of significant events during bag recording and playback

rosbag2_cpp/include/rosbag2_cpp/bag_events.hpp

@@ -0,0 +1,193 @@
+// Copyright 2021 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ROSBAG2_CPP__BAG_EVENTS_HPP_
+#define ROSBAG2_CPP__BAG_EVENTS_HPP_
+
+#include <functional>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "rclcpp/function_traits.hpp"
+#include "rosbag2_cpp/visibility_control.hpp"
+
+namespace rosbag2_cpp
+{
+
+namespace bag_events
+{
+
+/**
+ * \brief The types of bag events available for registering callbacks.
+ */
+enum class BagEvent
+{
+  /// The output bag file has been split, starting a new file.
+  WRITE_SPLIT,
+  /// Reading of the input bag file has gone over a split, opening the next file.
+  READ_SPLIT,
+};
+
+/**
+ * \brief The information structure passed to callbacks for the WRITE_SPLIT and READ_SPLIT events.
+ */
+struct BagSplitInfo
+{
+  /// The URI of the file that was closed.
+  std::string closed_file;
+  /// The URI of the file that was opened.
+  std::string opened_file;
+};
+
+using BagSplitCallbackType = std::function<void (BagSplitInfo &)>;
+
+/**
+ * \brief Use this structure to register callbacks with Writers.
+ */
+struct WriterEventCallbacks
+{
+  /// The callback to call for the WRITE_SPLIT event.
+  BagSplitCallbackType write_split_callback;
+};
+
+/**
+ * \brief Use this structure to register callbacks with Readers.
+ */
+struct ReaderEventCallbacks
+{
+  /// The callback to call for the READ_SPLIT event.
+  BagSplitCallbackType read_split_callback;
+};
+
+/**
+ * \brief Base class for event callbacks.
+ *
+ * This class should not be used directly.
+ */
+class BagEventCallbackBase
+{
+public:
+  using SharedPtr = std::shared_ptr<BagEventCallbackBase>;
+  using InfoPtr = std::shared_ptr<void>;
+
+  virtual ~BagEventCallbackBase()
+  {}
+
+  virtual void execute(InfoPtr & info) = 0;
+
+  virtual bool is_type(BagEvent event) const = 0;
+};
+
+/**
+ * \brief Templated class for storing an event callback.
+ *
+ * This class should not be used directly by users.
+ */
+template<typename EventCallbackT>
+class BagEventCallback : public BagEventCallbackBase
+{
+public:
+  BagEventCallback(const EventCallbackT & callback, BagEvent event)
+  : callback_(callback),
+    event_(event)
+  {}
+
+  virtual ~BagEventCallback()
+  {}
+
+  void execute(InfoPtr & info) override
+  {
+    callback_(*std::static_pointer_cast<EventCallbackInfoT>(info));
+  }
+
+  bool is_type(BagEvent event) const override
+  {
+    return event == event_;
+  }
+
+private:
+  using EventCallbackInfoT = typename std::remove_reference<typename
+      rclcpp::function_traits::function_traits<EventCallbackT>::template argument_type<0>>::type;
+
+  EventCallbackT callback_;
+  BagEvent event_;
+};
+
+/**
+ * \brief The class used to manage event callbacks registered with a Writer or Reader.
+ *
+ * Each implementation of the Writer and Reader interfaces should store one instance of this type.
+ * When new callbacks are registered, they should be passed to that instance using \ref
+ * add_event_callback. When an event occurs, the callbacks registered for it can be called by
+ * calling the \ref execute_callbacks method, passing in the event information.
+ */
+class EventCallbackManager
+{
+public:
+  /**
+   * \brief Add an event callback.
+   *
+   * \param callback The callback that should be called for the event.
+   * \param event The event, one of the values of the \ref BagEvent enumeration.
+   */
+  template<typename EventCallbackT>
+  void add_event_callback(const EventCallbackT & callback, const BagEvent event)
+  {
+    auto cb = std::make_shared<BagEventCallback<EventCallbackT>>(callback, event);
+    callbacks_.push_back(cb);
+  }
+
+  /**
+   * \brief Check if a callback is registered for the given event.
+   *
+   * \param event The event, one of the values of the \ref BagEvent enumeration.
+   * \return True if a callback is registered for the event, false otherwise.
+   */
+  bool has_callback_for_event(const BagEvent event) const
+  {
+    for (auto & cb : callbacks_) {
+      if (cb->is_type(event)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * \brief Execute all callbacks registered for the given event.
+   *
+   * The provided information value is passed to each callback by copy.
+   *
+   * \param event The event, one of the values of the \ref BagEvent enumeration.
+   * \param info The information relevant to the event that has occurred. The type varies by event.
+   */
+  void execute_callbacks(const BagEvent event, BagEventCallbackBase::InfoPtr info)
+  {
+    for (auto & cb : callbacks_) {
+      if (cb->is_type(event)) {
+        cb->execute(info);
+      }
+    }
+  }
+
+private:
+  std::vector<BagEventCallbackBase::SharedPtr> callbacks_;
+};
+
+}  // namespace bag_events
+
+}  // namespace rosbag2_cpp
+
+#endif  // ROSBAG2_CPP__BAG_EVENTS_HPP_

rosbag2_cpp/include/rosbag2_cpp/reader.hpp

@@ -23,6 +23,7 @@
 #include "rclcpp/serialization.hpp"
 #include "rclcpp/serialized_message.hpp"
 
+#include "rosbag2_cpp/bag_events.hpp"
 #include "rosbag2_cpp/converter_options.hpp"
 #include "rosbag2_cpp/readers/sequential_reader.hpp"
 #include "rosbag2_cpp/visibility_control.hpp"
@@ -179,6 +180,12 @@ class ROSBAG2_CPP_PUBLIC Reader final
     return *reader_impl_;
   }
 
+  /**
+   * \brief Add callbacks for events that may occur during bag reading.
+   * \param callbacks the structure containing the callback to add for each event.
+   */
+  void add_event_callbacks(bag_events::ReaderEventCallbacks & callbacks);
+
 private:
   std::unique_ptr<reader_interfaces::BaseReaderInterface> reader_impl_;
 };

rosbag2_cpp/include/rosbag2_cpp/reader_interfaces/base_reader_interface.hpp

@@ -19,6 +19,7 @@
 #include <vector>
 
 #include "rcutils/types.h"
+#include "rosbag2_cpp/bag_events.hpp"
 #include "rosbag2_cpp/converter_options.hpp"
 #include "rosbag2_cpp/visibility_control.hpp"
 
@@ -57,6 +58,8 @@ class ROSBAG2_CPP_PUBLIC BaseReaderInterface
   virtual void reset_filter() = 0;
 
   virtual void seek(const rcutils_time_point_value_t & timestamp) = 0;
+
+  virtual void add_event_callbacks(const bag_events::ReaderEventCallbacks & callbacks) = 0;
 };
 
 }  // namespace reader_interfaces

rosbag2_cpp/include/rosbag2_cpp/readers/sequential_reader.hpp

@@ -20,6 +20,7 @@
 #include <unordered_set>
 #include <vector>
 
+#include "rosbag2_cpp/bag_events.hpp"
 #include "rosbag2_cpp/converter.hpp"
 #include "rosbag2_cpp/reader_interfaces/base_reader_interface.hpp"
 #include "rosbag2_cpp/serialization_format_converter_factory.hpp"
@@ -101,6 +102,18 @@ class ROSBAG2_CPP_PUBLIC SequentialReader
   */
   virtual std::string get_current_uri() const;
 
+  /**
+   * \brief Add callbacks for events that may occur during bag reading.
+   * \param callbacks the structure containing the callback to add for each event.
+   */
+  void add_event_callbacks(const bag_events::ReaderEventCallbacks & callbacks) override;
+
+  /**
+   * \brief Check if a callback is registered for the given event.
+   * \return True if there is any callback registered for the event, false otherwise.
+   */
+  bool has_callback_for_event(const bag_events::BagEvent event) const;
+
 protected:
   /**
   * Opens the current file and sets up the filters in the new storage.
@@ -172,6 +185,8 @@ class ROSBAG2_CPP_PUBLIC SequentialReader
 private:
   rosbag2_storage::StorageOptions storage_options_;
   std::shared_ptr<SerializationFormatConverterFactoryInterface> converter_factory_{};
+
+  bag_events::EventCallbackManager callback_manager_;
 };
 
 }  // namespace readers

rosbag2_cpp/include/rosbag2_cpp/writer.hpp

@@ -25,6 +25,7 @@
 #include "rclcpp/serialized_message.hpp"
 #include "rclcpp/time.hpp"
 
+#include "rosbag2_cpp/bag_events.hpp"
 #include "rosbag2_cpp/converter_options.hpp"
 #include "rosbag2_cpp/visibility_control.hpp"
 #include "rosbag2_cpp/writers/sequential_writer.hpp"
@@ -204,6 +205,12 @@ class ROSBAG2_CPP_PUBLIC Writer final
     return *writer_impl_;
   }
 
+  /*
+   * \brief Add callbacks for events that may occur during bag writing.
+   * \param callbacks the structure containing the callback to add for each event.
+   */
+  void add_event_callbacks(bag_events::WriterEventCallbacks & callbacks);
+
 private:
   std::mutex writer_mutex_;
   std::unique_ptr<rosbag2_cpp::writer_interfaces::BaseWriterInterface> writer_impl_;

rosbag2_cpp/include/rosbag2_cpp/writer_interfaces/base_writer_interface.hpp

@@ -17,6 +17,7 @@
 
 #include <memory>
 
+#include "rosbag2_cpp/bag_events.hpp"
 #include "rosbag2_cpp/converter_options.hpp"
 #include "rosbag2_cpp/visibility_control.hpp"
 
@@ -51,6 +52,8 @@ class ROSBAG2_CPP_PUBLIC BaseWriterInterface
    * \returns true if snapshot is successful, false if snapshot fails or is not supported
    */
   virtual bool take_snapshot() = 0;
+
+  virtual void add_event_callbacks(const bag_events::WriterEventCallbacks & callbacks) = 0;
 };
 
 }  // namespace writer_interfaces

rosbag2_cpp/include/rosbag2_cpp/writers/sequential_writer.hpp

@@ -21,6 +21,7 @@
 #include <unordered_map>
 #include <vector>
 
+#include "rosbag2_cpp/bag_events.hpp"
 #include "rosbag2_cpp/cache/cache_consumer.hpp"
 #include "rosbag2_cpp/cache/circular_message_cache.hpp"
 #include "rosbag2_cpp/cache/message_cache.hpp"
@@ -114,6 +115,12 @@ class ROSBAG2_CPP_PUBLIC SequentialWriter
    */
   bool take_snapshot() override;
 
+  /**
+   * \brief Add callbacks for events that may occur during bag writing.
+   * \param callbacks the structure containing the callback to add for each event.
+   */
+  void add_event_callbacks(const bag_events::WriterEventCallbacks & callbacks) override;
+
 protected:
   std::string base_folder_;
   std::unique_ptr<rosbag2_storage::StorageFactoryInterface> storage_factory_;
@@ -162,6 +169,9 @@ class ROSBAG2_CPP_PUBLIC SequentialWriter
   /// Helper method to write messages while also updating tracked metadata.
   void write_messages(
     const std::vector<std::shared_ptr<const rosbag2_storage::SerializedBagMessage>> & messages);
+  bool is_first_message_ {true};
+
+  bag_events::EventCallbackManager callback_manager_;
 };
 
 }  // namespace writers

rosbag2_cpp/src/rosbag2_cpp/reader.cpp

@@ -92,4 +92,9 @@ void Reader::seek(const rcutils_time_point_value_t & timestamp)
   reader_impl_->seek(timestamp);
 }
 
+void Reader::add_event_callbacks(bag_events::ReaderEventCallbacks & callbacks)
+{
+  reader_impl_->add_event_callbacks(callbacks);
+}
+
 }  // namespace rosbag2_cpp

rosbag2_cpp/src/rosbag2_cpp/readers/sequential_reader.cpp

@@ -235,8 +235,12 @@ void SequentialReader::load_current_file()
 void SequentialReader::load_next_file()
 {
   assert(current_file_iterator_ != file_paths_.end());
+  auto info = std::make_shared<bag_events::BagSplitInfo>();
+  info->closed_file = get_current_file();
   current_file_iterator_++;
+  info->opened_file = get_current_file();
   load_current_file();
+  callback_manager_.execute_callbacks(bag_events::BagEvent::READ_SPLIT, info);
 }
 
 std::string SequentialReader::get_current_file() const
@@ -292,5 +296,19 @@ void SequentialReader::fill_topics_metadata()
   }
 }
 
+void SequentialReader::add_event_callbacks(const bag_events::ReaderEventCallbacks & callbacks)
+{
+  if (callbacks.read_split_callback) {
+    callback_manager_.add_event_callback(
+      callbacks.read_split_callback,
+      bag_events::BagEvent::READ_SPLIT);
+  }
+}
+
+bool SequentialReader::has_callback_for_event(const bag_events::BagEvent event) const
+{
+  return callback_manager_.has_callback_for_event(event);
+}
+
 }  // namespace readers
 }  // namespace rosbag2_cpp

rosbag2_cpp/src/rosbag2_cpp/writer.cpp

@@ -186,4 +186,9 @@ void Writer::write(
   return write(serialized_bag_message, topic_name, type_name, rmw_get_serialization_format());
 }
 
+void Writer::add_event_callbacks(bag_events::WriterEventCallbacks & callbacks)
+{
+  writer_impl_->add_event_callbacks(callbacks);
+}
+
 }  // namespace rosbag2_cpp