text: // Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  //
  // 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.
  
  #include <algorithm>
  #include <memory>
  #include <string>
  #include <utility>
  
  #include "rosbag2_cpp/cache/circular_message_cache.hpp"
  #include "rosbag2_cpp/cache/message_cache_circular_buffer.hpp"
  #include "rosbag2_cpp/cache/cache_buffer_interface.hpp"
  #include "rosbag2_cpp/logging.hpp"
  
  namespace rosbag2_cpp
  {
  namespace cache
  {
  
  CircularMessageCache::CircularMessageCache(size_t max_buffer_size)
  {
    producer_buffer_ = std::make_shared<MessageCacheCircularBuffer>(max_buffer_size);
    consumer_buffer_ = std::make_shared<MessageCacheCircularBuffer>(max_buffer_size);
  }
  
  CircularMessageCache::~CircularMessageCache()
  {
    // Unblock wait_for_data on destruction
    flushing_ = true;
    cache_condition_var_.notify_one();
  }
  
  void CircularMessageCache::push(std::shared_ptr<const rosbag2_storage::SerializedBagMessage> msg)
  {
    std::lock_guard<std::mutex> cache_lock(producer_buffer_mutex_);
    producer_buffer_->push(msg);
  }
  
  std::shared_ptr<CacheBufferInterface> CircularMessageCache::get_consumer_buffer()
  {
    consumer_buffer_mutex_.lock();
    return consumer_buffer_;
  }
  
  void CircularMessageCache::release_consumer_buffer()
  {
    consumer_buffer_mutex_.unlock();
  }
  
  void CircularMessageCache::begin_flushing()
  {
    {
      std::lock_guard<std::mutex> lock(producer_buffer_mutex_);
      flushing_ = true;
    }
    cache_condition_var_.notify_one();
  }
  
  void CircularMessageCache::done_flushing()
  {
    flushing_ = false;
  }
  
  void CircularMessageCache::notify_data_ready()
  {
    {
      std::lock_guard<std::mutex> lock(producer_buffer_mutex_);
      data_ready_ = true;
    }
    cache_condition_var_.notify_one();
  }
  
  void CircularMessageCache::wait_for_data()
  {
    std::unique_lock<std::mutex> producer_lock(producer_buffer_mutex_);
    if (!flushing_) {
      // Required condition check to protect against spurious wakeups
      cache_condition_var_.wait(
        producer_lock, [this] {
          return data_ready_ || flushing_;
        });
    }
  }
  
  void CircularMessageCache::swap_buffers()
  {
    std::lock_guard<std::mutex> producer_lock(producer_buffer_mutex_);
    // Swap buffers only if data is ready. Data not ready when we are calling flushing on exit and
    // we should not dump buffer on exit if snapshot has not been triggered.
    if (data_ready_) {
      std::lock_guard<std::mutex> consumer_lock(consumer_buffer_mutex_);
      consumer_buffer_->clear();
      std::swap(producer_buffer_, consumer_buffer_);
      data_ready_ = false;
    }
  }
  
  }  // namespace cache
  }  // namespace rosbag2_cpp
  