Class ConditionalSubscriber

Inheritance Relationships

Base Type

  • public cras::HasLogger

Derived Types

Class Documentation

class ConditionalSubscriber : public cras::HasLogger

A lazy subscriber that subscribes only when a condition is met.

Subclassed by cras::GenericLazyPubSub, cras::LazySubscriberBase< PublisherMsgType >

Public Types

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

Type of the function that connects the subscriber.

Param sub:

[out] Reference to the subscriber object to be created.

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

Type of the function that disconnects the subscriber.

Param Reference:

[inout] to the subscriber object to be disconnected.

Public Functions

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

Create the conditional subscriber.

Note

The base class itself does not regularly check the connect/disconnect condition. Subclasses are responsible for calling updateSubscription() when it is possible that the subscription condition changed.

Parameters:

  • connectFn – [in] The function that connects the subscriber. It should store the subscriber in the passed sub object.

  • disconnectFn – [in] The function that disconnects the subscriber. The sub object passed to the function is the one created previously by connectFn. The passed subscriber should be invalidated.

  • logHelper – [in] Logging helper.

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

Create the conditional subscriber.

Note

The base class itself does not regularly check the connect/disconnect condition. Subclasses are responsible for calling updateSubscription() when it is possible that the subscription condition changed.

Parameters:

  • connectFn – [in] The function that connects the subscriber. It should store the subscriber in the passed sub object. Disconnection is done by simply calling sub.shutdown().

  • logHelper – [in] Logging helper.

virtual ~ConditionalSubscriber()

Destroy this object and unsubscribe the subscriber if it was subscribed.

bool isLazy() const

Tell whether this subscriber has the lazy behavior enabled.

Returns:

Whether lazy behavior is enabled.

void setLazy(bool lazy)

Set whether the subscriber behaves in the lazy way.

Note

Calling this function checks the subscription condition and subscribes/unsubscribes as necessary.

Parameters:

lazy – [in] If set to false, the subscriber is switched to always subscribed mode.

bool isSubscribed() const

Whether the subscriber is currently subscribed to its topic or not.

Returns:

Whether the subscriber is currently subscribed to its topic or not.

Protected Functions

virtual bool shouldBeSubscribed() const = 0

Tell whether the subscriber should be subscribed or not.

Note

This function does not need to take into account the lazy flag.

Note

This function cannot lock connectMutex.

Returns:

Whether the subscriber should be subscribed or not.

void updateSubscription()

The callback called when the condition might have changed.

Note

This function locks connectMutex.

void updateSubscriptionNoLock()

The callback called when the condition might have changed.

Note

You have to lock this->connectMutex prior to calling this method.

void connectNoLock()

Connect the subscriber to its input.

Note

You have to lock this->connectMutex prior to calling this method.

void disconnectNoLock()

Disconnect the subscriber from its input.

Note

You have to lock this->connectMutex prior to calling this method.

Protected Attributes

::ros::Subscriber sub

The underlying subscriber (valid only when subscribed is true).

bool lazy = {true}

Whether the lazy behavior is enabled (if false, the subscriber is always subscribed).

bool subscribed = {false}

Whether the subscriber is currently subscribed to its topic or not.

ConnectFn connectFn

The function used to establish connection.

DisconnectFn disconnectFn

The function used to close connection.

mutable ::std::mutex connectMutex

Mutex protecting sub and subscribed.