Class CSubscriber¶

Defined in File ecal_subscriber.h

Inheritance Relationships¶

Derived Type¶

public eCAL::CMsgSubscriber< T > (Template Class CMsgSubscriber)

Class Documentation¶

class CSubscriber¶

eCAL subscriber class.

The CSubscriber

class is used to receive topics from matching eCAL publishers.

For receiving the topic payload the subscriber class provides a callback interface and overloaded receive methods.

// create subscriber, topic name "A"
eCAL::CSubscriber sub("A");

//---------------------------------------------------------------------------------------
// receive content with 100 ms timeout as standard string and read receive time stamp
//---------------------------------------------------------------------------------------
std::string rcv_s;
long long time = 0;
size_t rcv_len = sub.Receive(rcv_s, &time, 100);

//---------------------------------------------------------------------------------------
// receive content with a callback functions
//---------------------------------------------------------------------------------------
void OnReceive(const char* topic_name_, const struct eCAL::SReceiveCallbackData* data_)
{
  size_t      size = data_->size;
  const void* data = data_->buf;
  long long   time = data_->time;
}

// add callback
sub.AddReceiveCallback(std::bind(OnReceive, std::placeholders::_1, std::placeholders::_2));

// idle main thread
while(eCAL::Ok())
{
  // sleep 100 ms
  std::this_thread::sleep_for(std::chrono::milliseconds(100));
}

Subclassed by eCAL::CMsgSubscriber< T >

Public Functions

CSubscriber()¶: Constructor.

CSubscriber(const std::string &topic_name_, const std::string &topic_type_ = "", const std::string &topic_desc_ = "")¶

Constructor.

Parameters

topic_name_ – Unique topic name.
topic_type_ – Type name (optional for type checking).
topic_desc_ – Type description (optional for description checking).

virtual ~CSubscriber()¶: Destructor.

CSubscriber(const CSubscriber&) = delete¶: CSubscribers are non-copyable.

CSubscriber &operator=(const CSubscriber&) = delete¶: CSubscribers are non-copyable.

CSubscriber(CSubscriber &&rhs) noexcept¶: CSubscribers are move-enabled.

CSubscriber &operator=(CSubscriber &&rhs) noexcept¶: CSubscribers are move-enabled.

bool Create(const std::string &topic_name_, const std::string &topic_type_ = "", const std::string &topic_desc_ = "")¶

Creates this object.

Parameters

topic_name_ – Unique topic name.
topic_type_ – Type name (optional for type checking).
topic_desc_ – Type description (optional for description checking).

Returns

true if it succeeds, false if it fails.

bool Destroy()¶

Destroys this object.

Returns: true if it succeeds, false if it fails.

bool SetQOS(const QOS::SReaderQOS &qos_)¶

Set subscriber quality of service attributes.

Parameters: qos_ – Quality of service policies.
Returns: True if it succeeds, false if it fails.

QOS::SReaderQOS GetQOS()¶

Get current subscriber quality of service attributes.

Returns: Quality of service attributes.

bool SetID(const std::set<long long> &id_set_)¶

Set a set of id’s to prefiltering topics (see CPublisher::SetID).

Parameters: id_set_ – Set of id’s.
Returns: True if it succeeds, false if it fails.

bool SetAttribute(const std::string &attr_name_, const std::string &attr_value_)¶

Sets subscriber attribute.

This feature is marked as experimental:

Parameters

attr_name_ – Attribute name.
attr_value_ – Attribute value.

Returns

True if it succeeds, false if it fails.

bool ClearAttribute(const std::string &attr_name_)¶

Removes subscriber attribute.

This feature is marked as experimental:

Parameters: attr_name_ – Attribute name.
Returns: True if it succeeds, false if it fails.

size_t Receive(std::string &buf_, long long *time_ = nullptr, int rcv_timeout_ = 0) const¶

Receive a message from the publisher.

Parameters

buf_ – [out] Standard string for copying message content.
time_ – [out] Time from publisher in us (default = nullptr).
rcv_timeout_ – Maximum time before receive operation returns (in milliseconds, -1 means infinite).

Returns

Length of received buffer.

bool ReceiveBuffer(std::string &buf_, long long *time_ = nullptr, int rcv_timeout_ = 0) const¶

Receive a message from the publisher (able to process zero length buffer).

Parameters

buf_ – [out] Standard string for copying message content.
time_ – [out] Time from publisher in us (default = nullptr).
rcv_timeout_ – Maximum time before receive operation returns (in milliseconds, -1 means infinite).

Returns

True if it succeeds, false if it fails.

bool AddReceiveCallback(ReceiveCallbackT callback_)¶

Add callback function for incoming receives.

Parameters: callback_ – The callback function to add.
Returns: True if succeeded, false if not.

bool RemReceiveCallback()¶

Remove callback function for incoming receives.

Returns: True if succeeded, false if not.

bool AddEventCallback(eCAL_Subscriber_Event type_, SubEventCallbackT callback_)¶

Add callback function for subscriber events.

Parameters

type_ – The event type to react on.
callback_ – The callback function to add.

Returns

True if succeeded, false if not.

bool RemEventCallback(eCAL_Subscriber_Event type_)¶

Remove callback function for subscriber events.

Parameters: type_ – The event type to remove.
Returns: True if succeeded, false if not.

inline bool IsCreated() const¶

Query if this object is created.

Returns: true if created, false if not.

size_t GetPublisherCount() const¶

Query the number of publishers.

Returns: Number of publishers.

std::string GetTopicName() const¶

Gets name of the connected topic.

Returns: The topic name.

std::string GetTypeName() const¶

Gets type of the connected topic.

Returns: The type name.

std::string GetDescription() const¶

Gets description of the connected topic.

Returns: The description.

bool SetTimeout(int timeout_)¶

Set the timeout parameter for triggering the timeout callback.

Parameters: timeout_ – The timeout in milliseconds.
Returns: True if succeeded, false if not.

std::string Dump(const std::string &indent_ = "") const¶

Dump the whole class state into a string.

Parameters: indent_ – Indentation used for dump.
Returns: The dump sting.