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ZPOLLER(3) CZMQ Manual ZPOLLER(3) NAME zpoller - Class for trivial socket poller class SYNOPSIS // This is a stable class, and may not change except for emergencies. It // is provided in stable builds. // 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. CZMQ_EXPORT zpoller_t * zpoller_new (void *reader, ...); // Destroy a poller CZMQ_EXPORT void zpoller_destroy (zpoller_t **self_p); // 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, a zactor_t instance or a // file handle. CZMQ_EXPORT int zpoller_add (zpoller_t *self, void *reader); // 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. CZMQ_EXPORT int zpoller_remove (zpoller_t *self, void *reader); // 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). CZMQ_EXPORT void zpoller_set_nonstop (zpoller_t *self, bool nonstop); // Poll the registered readers for I/O, return first reader that has input. // The reader will be a libzmq void * socket, a zsock_t, a zactor_t // instance or a file handle 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. CZMQ_EXPORT void * zpoller_wait (zpoller_t *self, int timeout); // Return true if the last zpoller_wait () call ended because the timeout // expired, without any error. CZMQ_EXPORT bool zpoller_expired (zpoller_t *self); // Return true if the last zpoller_wait () call ended because the process // was interrupted, or the parent context was destroyed. CZMQ_EXPORT bool zpoller_terminated (zpoller_t *self); // Self test of this class. CZMQ_EXPORT void zpoller_test (bool verbose); Please add '@interface' section in './../src/zpoller.c'. DESCRIPTION The zpoller class provides a minimalist interface to ZeroMQ's zmq_poll API, for the very common case of reading from a number of sockets. It does not provide polling for output, nor polling on file handles. If you need either of these, use the zmq_poll API directly. The class implements the poller using the zmq_poller API if that exists, else does the work itself. EXAMPLE From zpoller_test method. // Create a few sockets zsock_t *vent = zsock_new (ZMQ_PUSH); assert (vent); int port_nbr = zsock_bind (vent, "tcp://127.0.0.1:*"); assert (port_nbr != -1); zsock_t *sink = zsock_new (ZMQ_PULL); assert (sink); int rc = zsock_connect (sink, "tcp://127.0.0.1:%d", port_nbr); assert (rc != -1); zsock_t *bowl = zsock_new (ZMQ_PULL); assert (bowl); zsock_t *dish = zsock_new (ZMQ_PULL); assert (dish); // Set up poller zpoller_t *poller = zpoller_new (bowl, dish, NULL); assert (poller); // Add a reader to the existing poller rc = zpoller_add (poller, sink); assert (rc == 0); zstr_send (vent, "Hello, World"); // We expect a message only on the sink zsock_t *which = (zsock_t *) zpoller_wait (poller, -1); assert (which == sink); assert (zpoller_expired (poller) == false); assert (zpoller_terminated (poller) == false); char *message = zstr_recv (which); assert (streq (message, "Hello, World")); zstr_free (&message); // Stop polling reader rc = zpoller_remove (poller, sink); assert (rc == 0); // Removing a non-existent reader shall fail rc = zpoller_remove (poller, sink); assert (rc == -1); assert (errno == EINVAL); // Check we can poll an FD rc = zsock_connect (bowl, "tcp://127.0.0.1:%d", port_nbr); assert (rc != -1); SOCKET fd = zsock_fd (bowl); rc = zpoller_add (poller, (void *) &fd); assert (rc != -1); zstr_send (vent, "Hello again, world"); assert (zpoller_wait (poller, 500) == &fd); // Check zpoller_set_nonstop () zsys_interrupted = 1; zpoller_wait (poller, 0); assert (zpoller_terminated (poller)); zpoller_set_nonstop (poller, true); zpoller_wait (poller, 0); assert (!zpoller_terminated (poller)); zsys_interrupted = 0; zpoller_destroy (&poller); zsock_destroy (&vent); zsock_destroy (&sink); zsock_destroy (&bowl); zsock_destroy (&dish); #ifdef ZMQ_SERVER // Check thread safe sockets zpoller_destroy (&poller); zsock_t *client = zsock_new (ZMQ_CLIENT); assert (client); zsock_t *server = zsock_new (ZMQ_SERVER); assert (server); poller = zpoller_new (client, server, NULL); assert (poller); port_nbr = zsock_bind (server, "tcp://127.0.0.1:*"); assert (port_nbr != -1); rc = zsock_connect (client, "tcp://127.0.0.1:%d", port_nbr); assert (rc != -1); zstr_send (client, "Hello, World"); // We expect a message only on the server which = (zsock_t *) zpoller_wait (poller, -1); assert (which == server); assert (zpoller_expired (poller) == false); assert (zpoller_terminated (poller) == false); message = zstr_recv (which); assert (streq (message, "Hello, World")); zstr_free (&message); zpoller_destroy (&poller); zsock_destroy (&client); zsock_destroy (&server); #endif #if defined (__WINDOWS__) zsys_shutdown(); #endif AUTHORS The czmq manual was written by the authors in the AUTHORS file. RESOURCES Main web site: Report bugs to the email <zeromq-dev@lists.zeromq.org[1]> COPYRIGHT Copyright (c) the Contributors as noted in the AUTHORS file. This file is part of CZMQ, the high-level C binding for 0MQ: http://czmq.zeromq.org. This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/. LICENSE included with the czmq distribution. NOTES 1. zeromq-dev@lists.zeromq.org mailto:zeromq-dev@lists.zeromq.org CZMQ 4.2.1 11/01/2025 ZPOLLER(3)
NAME | SYNOPSIS | DESCRIPTION | EXAMPLE | AUTHORS | RESOURCES | COPYRIGHT | NOTES
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