/**
* This method is applied whenever messages are received by this operator.
*
* @param msg the message itself
* @param from the operator from which the message has been sent
* @return the post-processed message after processing and forwarding the merged message of all
* operands, which has been received from the succeeding operators
*/
public Message receive(Message message, final BasicOperator from) {
Message msg = message;
if (from != null) {
Map<BasicOperator, Message> received = this.messages.get(msg.getId());
if (received == null) {
received = new HashMap<BasicOperator, Message>();
this.messages.put(msg.getId(), received);
}
received.put(from, msg);
final HashSet<BasicOperator> operatorsWithoutCycles = new HashSet<BasicOperator>();
operatorsWithoutCycles.addAll(this.precedingOperators);
operatorsWithoutCycles.removeAll(this.cycleOperands);
if (!received.keySet().containsAll(operatorsWithoutCycles)) {
return null;
}
if (received.keySet().containsAll(this.precedingOperators)) {
this.messages.remove(msg.getId());
}
msg = msg.merge(received.values(), this);
}
msg = msg.preProcess(this);
msg = forwardMessage(msg);
if (msg == null) return null;
else return msg.postProcess(this);
}
/**
* This method sends a message.
*
* @param msg the message to be sent
* @return the received (and post-processed) message from the succeeding operators
*/
public Message sendMessage(final Message msg) {
Message msgResult = this.forwardMessage(msg.preProcess(this));
// postprocess anyway one message, does not matter if the resultant msg is null or not to allow
// processing right after initialization
if (msgResult == null) {
return msg.postProcess(this);
} else {
return msgResult.postProcess(this);
}
}