ZMQ socket connection timeout

问题:

I'm using C++ binding for ZMQ (cppzmq) and I'm trying to set the connection timeout of TCP socket using a .setsockopt()-method like this:

int connectTimeout = 1000;
socket.setsockopt(ZMQ_CONNECT_TIMEOUT, &connectTimeout, sizeof(connectTimeout));
socket.connect(clientConfiguration.uri);

However, I dont see anything (exception thrown?) happening until code reaches actual .send()/.recv() on the socket. Just to make sure the socket has a chance to throw I put a sleep between .connect() and .send() methods.

According to the documentation .zmq_connect() just enters a READY-state without making actual connection to the endpoint. So the question is when and how I should experience the connection timeout?

回答1:

So the question is when and how I should experience the connection timeout ?

When ?

Well, actually never directly as this is just the API-exposed setting of ZeroMQ Context()-instances' internal Finite-State-Machine modus operandi ( here the .setsockopt() sets the selected transport-class behind-the-API-curtain ISO-OSI-L3 details ).

How_{( if at all )} ?

Well, there are some other .setsockopt() details, that ( if put on ) may indirectly sense the impact of the set ZMQ_CONNECT_TIMEOUT connection timeout. Here again, only indirectly, by a modified FSM-behaviour, i.e. in a way, how the .Context()-engine instance will happen to respond to such event ( all purely internally, behind the Curtain of API - that's why we methodologically use the API method for separation of concerns, don't we ? ).

For further details ref.:

• API details about ZMQ_IMMEDIATE,
• API details about ZMQ_RECONNECT_IVL,
• API details about ZMQ_RECONNECT_IVL_MAX.
  _{( API versions evolve, be aware that not all distributed-system agents share the same ZeroMQ API version. So best remember the Zen-of-Zero and feel free to re-use the anxient designers' directive #ASSUME NOTHING. )}

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A TRAILER BONUS :

If not familiar with the ZeroMQ instrumentation, one may find useful this 5-seconds read into the main conceptual differences in the [ ZeroMQ hierarchy in less than a five seconds ] Section,

_{( courtesy Martin Sústrik, co-father of both ZeroMQ + nanomsg. Respect! )}