ZMQConnection Class Reference

Base class for every connection with virtual functions to be implemented: More...

#include <ZMQConnection.h>

Inheritance diagram for ZMQConnection:

Collaboration diagram for ZMQConnection:

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
virtual	~ZMQConnection ()=default
	Virtual default destructor.
virtual bool	isReady () const
	Return true of this connection is able to send messages right now. Can be overloaded in derived classes.
virtual std::vector< zmq::socket_t * >	getSockets () const =0
	Return the list of sockets which should be polled on to check for incoming messages. Can be empty. Must be overloaded in derived classes.
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).

Private Attributes
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

Base class for every connection with virtual functions to be implemented:

• isReady(): return True if this connection can send events
• getSockets(): return the list of sockets to be used while polling for incoming messages (can be empty)

Additionally, it has static functions for polling on a list of connections or checking if a specific connection has messages.

Definition at line 31 of file ZMQConnection.h.

Member Typedef Documentation

ReactorFunction

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

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

Definition at line 34 of file ZMQConnection.h.

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]);
}

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()

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

pure virtual

Return the list of sockets which should be polled on to check for incoming messages. Can be empty. Must be overloaded in derived classes.

Implemented in ZMQConnectionOverSocket, and ZMQNullConnection.

hasMessage()

bool hasMessage ( const ZMQConnection *  connection )

static

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

virtual

Return true of this connection is able to send messages right now. Can be overloaded in derived classes.

Reimplemented in ZMQLoadBalancedOutput, and ZMQRawOutput.

Definition at line 15 of file ZMQConnection.cc.

{
  return true;
}

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  )

static

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_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_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_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/ZMQConnection.h
• framework/pcore/zmq/connections/src/ZMQConnection.cc