event-driven reactor Create new poller, specifying zero or more readers. The list of readers ends in a NULL. Each reader can be a zsock_t instance, a zactor_t instance, a libzmq socket (void *), or a file handle. Destroy a poller Add a reader to be polled. Returns 0 if OK, -1 on failure. The reader may be a libzmq void * socket, a zsock_t instance, or a zactor_t instance. Remove a reader from the poller; returns 0 if OK, -1 on failure. The reader must have been passed during construction, or in an zpoller_add () call. By default the poller stops if the process receives a SIGINT or SIGTERM signal. This makes it impossible to shut-down message based architectures like zactors. This method lets you switch off break handling. The default nonstop setting is off (false). Poll the registered readers for I/O, return first reader that has input. The reader will be a libzmq void * socket, or a zsock_t or zactor_t instance as specified in zpoller_new/zpoller_add. The timeout should be zero or greater, or -1 to wait indefinitely. Socket priority is defined by their order in the poll list. If you need a balanced poll, use the low level zmq_poll method directly. If the poll call was interrupted (SIGINT), or the ZMQ context was destroyed, or the timeout expired, returns NULL. You can test the actual exit condition by calling zpoller_expired () and zpoller_terminated (). The timeout is in msec. Return true if the last zpoller_wait () call ended because the timeout expired, without any error. Return true if the last zpoller_wait () call ended because the process was interrupted, or the parent context was destroyed.