ZMQRawOutput Class Reference

Output connection to speak to non-zmq sockets via a ZMQ_STREAM socket. More...

#include <ZMQRawConnection.h>

Inheritance diagram for ZMQRawOutput:

Collaboration diagram for ZMQRawOutput:

Public Types
using	ReactorFunction = std::function< void(void)>
	Typedef of a function which will be called if a connection has a message.

Public Member Functions
	ZMQRawOutput (const std::string &outputAddress, bool addEventSize, const std::shared_ptr< ZMQParent > &parent)
	Create a new raw output connection. The bind or connect behavior is chosen according to the given address.
virtual void	handleEvent (zmq::message_t message)
	Pass on the message - maybe by prefixing it with a htonl-converted data size in bytes.
void	handleIncomingData ()
	Handle incoming data: a socket (dis)connect.
bool	isReady () const final
	If no socket is connected, this connection is not ready.
std::vector< zmq::socket_t * >	getSockets () const final
	The socket used for polling is just the stored socket.
std::string	getEndPoint () const
	Return the connection string for this socket.
virtual std::string	getMonitoringJSON () const
	Convert the stored monitoring values to a JSON string ready for sending out via a message.
template<class AClass >
void	log (const std::string &key, const AClass &value)
	Store a value under a certain key. Different types of values can be stored, namely long, double or string. Mixtures are not allowed for a given key.
void	increment (const std::string &key)
	Increment the value with the given key (only numerical values). If not present, set to 1.
void	decrement (const std::string &key)
	Decrement the value with the given key (only numerical values). If not present, set to -1.
template<size_t MAX_SIZE = 100>
void	average (const std::string &key, double value)
	Instead of storeing the double value directly under the given key, store the average of the last MAX_SIZE values.
template<size_t AVERAGE_SIZE = 2000>
void	timeit (const std::string &key)
	Measure the rate of calls with the same key every AVERAGE_SIZE calls (and also display the last time AVERAGE_SIZE was reached under <key>_last_measurement)
void	logTime (const std::string &key)
	Store the current time as a string under the given key.

Static Public Member Functions
static bool	poll (const std::map< const ZMQConnection *, ReactorFunction > &connectionList, int timeout)
	Poll on the given connections and call the attached function if a messages comes in.
static bool	hasMessage (const ZMQConnection *connection)
	Check if the given connection as an incoming message (right now, no waiting).

Protected Attributes
std::shared_ptr< ZMQParent >	m_parent
	The shared ZMQParent instance.
std::unique_ptr< zmq::socket_t >	m_socket
	The memory of the socket. Needs to be initialized in a derived class.

Private Attributes
std::string	m_dataIdentity = ""
	Internal storage of the connected identity to no have multiple connections.
bool	m_addEventSize = false
	Parameter to add the event size to a message.
std::map< std::string, std::variant< long, double, std::string > >	m_monitoring
	Internal storage of all stored values.
std::unordered_map< std::string, std::tuple< std::vector< double >, size_t > >	m_averages
	Internal storage of the previous values when calculating averages.
std::unordered_map< std::string, std::tuple< unsigned long, std::chrono::system_clock::time_point > >	m_timeCounters
	Internal storage how often the timeit function for a given key was called and when it has last reached MAX_SIZE.

Detailed Description

Output connection to speak to non-zmq sockets via a ZMQ_STREAM socket.

If a socket is connected, sends out the given message over this socket as it is. If addEventSize is true, will prefix the message with the htonl-converted size of the message in bytes. Compare this to the receiveEventMessages setting of the ZMQRawInput connection. If no socket is connected, this connection is not ready.

Please note that although it is an output connection, there will still be "incoming messages", namely whenever the socket connects or disconnects. So you need to poll on this connection. Can only send messages to a single connected socket.

Definition at line 87 of file ZMQRawConnection.h.

Member Typedef Documentation

ReactorFunction

using ReactorFunction = std::function<void(void)>

inherited

Typedef of a function which will be called if a connection has a message.

Definition at line 34 of file ZMQConnection.h.

Constructor & Destructor Documentation

ZMQRawOutput()

ZMQRawOutput	(	const std::string &	outputAddress,
		bool	addEventSize,
		const std::shared_ptr< ZMQParent > &	parent
	)

Create a new raw output connection. The bind or connect behavior is chosen according to the given address.

Definition at line 144 of file ZMQRawConnection.cc.

                                                                   : ZMQConnectionOverSocket(
                               parent), m_addEventSize(addEventSize)
{
  // We clear all our internal state and counters
  log("data_size", 0.0);
  log("sent_events", 0l);
  log("event_rate", 0.0);
 
  log("socket_state", "disconnected");
  log("socket_connects", 0l);
  log("socket_disconnects", 0l);
 
  // STREAM is the ZMQ type for raw, non ZMQ connections
  m_socket = m_parent->createSocket<ZMQ_STREAM>(outputAddress);
}

Member Function Documentation

decrement()

void decrement ( const std::string &  key )

inherited

Decrement the value with the given key (only numerical values). If not present, set to -1.

Definition at line 37 of file ZMQLogger.cc.

{
  std::visit(Decrementor{}, m_monitoring[key]);
}

getEndPoint()

std::string getEndPoint ( ) const

inherited

Return the connection string for this socket.

Definition at line 87 of file ZMQConnection.cc.

{
  std::string endpoint{""};
  if (m_socket) {
    endpoint = m_socket->get(zmq::sockopt::last_endpoint);
  }
  return endpoint;
}

getMonitoringJSON()

std::string getMonitoringJSON ( ) const

virtualinherited

Convert the stored monitoring values to a JSON string ready for sending out via a message.

Definition at line 15 of file ZMQLogger.cc.

{
  std::stringstream buffer;
  buffer << "{";
  bool first = true;
  for (const auto& keyValue : m_monitoring) {
    if (not first) {
      buffer << ", ";
    }
    first = false;
    buffer << "\"" << keyValue.first << "\": ";
    buffer << std::visit(toJSON{}, keyValue.second);
  }
  buffer << "}" << std::endl;
  return buffer.str();
}

getSockets()

std::vector< zmq::socket_t * > getSockets ( ) const

finalvirtualinherited

The socket used for polling is just the stored socket.

Implements ZMQConnection.

Definition at line 82 of file ZMQConnection.cc.

{
  return {m_socket.get()};
}

handleEvent()

void handleEvent ( zmq::message_t  message )

virtual

Pass on the message - maybe by prefixing it with a htonl-converted data size in bytes.

Definition at line 161 of file ZMQRawConnection.cc.

{
  // Send the message. If requested, add the message size in front of the message
  B2ASSERT("Data Socket needs to be connected", not m_dataIdentity.empty());
 
  const auto dataSize = message.size();
 
  average("data_size", dataSize);
  increment("sent_events");
  timeit("event_rate");
 
  m_socket->send(ZMQMessageHelper::createZMQMessage(m_dataIdentity), zmq::send_flags::sndmore);
  if (not m_addEventSize) {
    m_socket->send(std::move(message), zmq::send_flags::none);
  } else {
    zmq::message_t tmpMessage(message.size() + sizeof(int));
    const int messageSize = htonl(message.size());
    memcpy(tmpMessage.data<char>(), &messageSize, sizeof(int));
    memcpy(tmpMessage.data<char>() + sizeof(int), message.data(), message.size());
    m_socket->send(std::move(tmpMessage), zmq::send_flags::none);
  }
}

handleIncomingData()

void handleIncomingData

(

)

Handle incoming data: a socket (dis)connect.

Definition at line 184 of file ZMQRawConnection.cc.

{
  // The only possibility that we can receive a message is when the client connects or disconnects
  zmq::message_t identity;
  auto received = m_socket->recv(identity, zmq::recv_flags::none);
  B2ASSERT("No message received", received);
  zmq::message_t nullMessage;
  received = m_socket->recv(nullMessage, zmq::recv_flags::none);
  B2ASSERT("No message received", received);
  std::string identityString(identity.data<char>(), identity.size());
 
  if (m_dataIdentity.empty()) {
    m_dataIdentity = identityString;
    log("socket_state", "connected");
    increment("socket_connects");
  } else {
    B2ASSERT("The app can only handle a single connection!", m_dataIdentity == identityString);
    m_dataIdentity = "";
    log("socket_state", "disconnected");
    increment("socket_disconnects");
  }
}

hasMessage()

bool hasMessage ( const ZMQConnection *  connection )

staticinherited

Check if the given connection as an incoming message (right now, no waiting).

Definition at line 20 of file ZMQConnection.cc.

{
  // Just poll with 0 timeout and no reaction function. Hacky trick to reduce code duplication
  const auto emptyFunction = []() {};
  return ZMQConnection::poll({{connection, emptyFunction}}, 0);
}

increment()

void increment ( const std::string &  key )

inherited

Increment the value with the given key (only numerical values). If not present, set to 1.

Definition at line 32 of file ZMQLogger.cc.

{
  std::visit(Incrementor{}, m_monitoring[key]);
}

isReady()

bool isReady ( ) const

finalvirtual

If no socket is connected, this connection is not ready.

Reimplemented from ZMQConnection.

Definition at line 207 of file ZMQRawConnection.cc.

{
  // Only ready of the client connected
  return not m_dataIdentity.empty();
}

logTime()

void logTime ( const std::string &  key )

inherited

Store the current time as a string under the given key.

Definition at line 42 of file ZMQLogger.cc.

{
  auto current = std::chrono::system_clock::now();
  auto displayTime = std::chrono::system_clock::to_time_t(current);
  log(key, std::ctime(&displayTime));
}

poll()

bool poll ( const std::map< const ZMQConnection *, ReactorFunction > &  connectionList, int  timeout  )

staticinherited

Poll on the given connections and call the attached function if a messages comes in.

If after timeout milliseconds still no message is received, return anyways. If timeout is 0, do not wait. If timeout is -1, wait infinitely.

Returns true if a message was received on any socket, false otherwise. Attention: in case of an interrupted system call (e.g. because a signal was received) the function might return anyways with a negative result even before the timeout!

Definition at line 27 of file ZMQConnection.cc.

{
  std::vector<const ReactorFunction*> socketMapping;
  std::vector<zmq::pollitem_t> pollItems;
 
  // zmq needs a special format for its polling, so create it here.
  for (const auto& [connection, function] : connectionList) {
    auto sockets = connection->getSockets();
    for (zmq::socket_t* socket : sockets) {
      zmq::pollitem_t pollItem;
      pollItem.socket = static_cast<void*>(*socket);
      pollItem.events = ZMQ_POLLIN;
      pollItem.revents = 0;
      pollItems.push_back(std::move(pollItem));
 
      // but keep reference to the original function, so we can call the correct one later
      socketMapping.push_back(&function);
    }
  }
 
  if (pollItems.empty()) {
    return false;
  }
 
  try {
    zmq::poll(&pollItems[0], pollItems.size(), timeout);
 
    bool anySocket = false;
    unsigned int counter = 0;
    for (const auto& pollItem : pollItems) {
      if (pollItem.revents & ZMQ_POLLIN) {
        anySocket = true;
        const auto* functionPtr = socketMapping.at(counter);
        const auto function = *functionPtr;
        function();
      }
      counter++;
    }
 
    return anySocket;
  } catch (zmq::error_t& error) {
    if (error.num() == EINTR) {
      // Could happen if there was an interrupt, return false so the caller knows the time did not pass already
      return false;
    } else {
      // cannot handle, rethrow exception
      throw;
    }
  }
}

Member Data Documentation

m_addEventSize

bool m_addEventSize = false

private

Parameter to add the event size to a message.

Definition at line 103 of file ZMQRawConnection.h.

m_averages

std::unordered_map<std::string, std::tuple<std::vector<double>, size_t> > m_averages

privateinherited

Internal storage of the previous values when calculating averages.

Definition at line 60 of file ZMQLogger.h.

m_dataIdentity

std::string m_dataIdentity = ""

private

Internal storage of the connected identity to no have multiple connections.

Definition at line 101 of file ZMQRawConnection.h.

m_monitoring

std::map<std::string, std::variant<long, double, std::string> > m_monitoring

privateinherited

Internal storage of all stored values.

Definition at line 58 of file ZMQLogger.h.

m_parent

std::shared_ptr<ZMQParent> m_parent

protectedinherited

The shared ZMQParent instance.

Definition at line 75 of file ZMQConnection.h.

m_socket

std::unique_ptr<zmq::socket_t> m_socket

protectedinherited

The memory of the socket. Needs to be initialized in a derived class.

Definition at line 77 of file ZMQConnection.h.

m_timeCounters

std::unordered_map<std::string, std::tuple<unsigned long, std::chrono::system_clock::time_point> > m_timeCounters

privateinherited

Internal storage how often the timeit function for a given key was called and when it has last reached MAX_SIZE.

Definition at line 62 of file ZMQLogger.h.

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The documentation for this class was generated from the following files:

• framework/pcore/zmq/connections/include/ZMQRawConnection.h
• framework/pcore/zmq/connections/src/ZMQRawConnection.cc