lazy_subscriber.hpp

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#pragma once

// SPDX-License-Identifier: BSD-3-Clause
// SPDX-FileCopyrightText: Czech Technical University in Prague

#include <functional>
#include <memory>
#include <mutex>
#include <string>

#include <boost/functional.hpp>

#include <ros/node_handle.h>
#include <ros/publisher.h>
#include <ros/single_subscriber_publisher.h>
#include <ros/subscriber.h>

#include <cras_cpp_common/log_utils.h>
#include <cras_cpp_common/log_utils/node.h>

namespace cras
{

class ConditionalSubscriber : public ::cras::HasLogger
{
public:
  typedef ::std::function<void(::ros::Subscriber& sub)> ConnectFn;

  typedef ::std::function<void(::ros::Subscriber& sub)> DisconnectFn;

  ConditionalSubscriber(ConnectFn connectFn, DisconnectFn disconnectFn,
    const ::cras::LogHelperPtr& logHelper = ::std::make_shared<::cras::NodeLogHelper>());

  explicit ConditionalSubscriber(ConnectFn connectFn,
    const ::cras::LogHelperPtr& logHelper = ::std::make_shared<::cras::NodeLogHelper>());

  virtual ~ConditionalSubscriber();

  bool isLazy() const;

  void setLazy(bool lazy);

  bool isSubscribed() const;

protected:
  virtual bool shouldBeSubscribed() const = 0;

  void updateSubscription();

  void updateSubscriptionNoLock();

  void connectNoLock();

  void disconnectNoLock();

  ::ros::Subscriber sub;

  bool lazy {true};

  bool subscribed {false};

  ConnectFn connectFn;

  DisconnectFn disconnectFn;

  mutable ::std::mutex connectMutex;
};

template<typename PublisherMsgType>
class LazySubscriberBase : public ::cras::ConditionalSubscriber
{
public:
  LazySubscriberBase(::ros::NodeHandle publisherNh, const ::std::string& publisherTopic,
    typename ::cras::ConditionalSubscriber::ConnectFn connectFn,
    typename ::cras::ConditionalSubscriber::DisconnectFn disconnectFn,
    const ::cras::LogHelperPtr& logHelper = ::std::make_shared<::cras::NodeLogHelper>());

  LazySubscriberBase(::ros::NodeHandle publisherNh, const ::std::string& publisherTopic,
    typename ::cras::ConditionalSubscriber::ConnectFn connectFn,
    const ::cras::LogHelperPtr& logHelper = ::std::make_shared<::cras::NodeLogHelper>());

protected:
  void connectCb(const ::ros::SingleSubscriberPublisher&);

  bool shouldBeSubscribed() const override;

  ::ros::Publisher pub;
};

template<typename PublisherMsgType, typename CallbackType = const PublisherMsgType&>
class LazySubscriber : public ::cras::LazySubscriberBase<PublisherMsgType>
{
public:
  LazySubscriber(::ros::NodeHandle publisherNh, const ::std::string& publisherTopic,
                 ::ros::NodeHandle subscriberNh, const ::std::string& subscriberTopic, size_t subscriberQueueSize,
                 ::boost::function<void(CallbackType)> subscriberCallback, ::ros::SubscribeOptions subscribeOptions,
                 const ::cras::LogHelperPtr& logHelper = ::std::make_shared<::cras::NodeLogHelper>());

  LazySubscriber(::ros::NodeHandle publisherNh, const ::std::string& publisherTopic,
                 ::ros::NodeHandle subscriberNh, const ::std::string& subscriberTopic, size_t subscriberQueueSize,
                 ::boost::function<void(CallbackType)> subscriberCallback,
                 const ::cras::LogHelperPtr& logHelper = ::std::make_shared<::cras::NodeLogHelper>());
};

}

#include "impl/lazy_subscriber.hpp"