ZMQPoll::poll

Poll the items

Description

public int ZMQPoll::poll(array &$readable, array &$writable, int $timeout = -1)

Polls the items in the current poll set. The readable and writable items are returned in the readable and writable parameters. ZMQPoll::getLastErrors can be used to check if there were errors.

Parameters

readable: Array where readable ZMQSockets/PHP streams are returned. The array will be cleared at the beginning of the operation.
writable: Array where writable ZMQSockets/PHP streams are returned. The array will be cleared at the beginning of the operation.
timeout: Timeout for the operation. -1 means that poll waits until at least one item has activity. Please note that starting from version 1.0.0 the poll timeout is defined in milliseconds, rather than microseconds.

Return Values

Returns an integer representing the amount of items with activity.

Errors/Exceptions

Throws ZMQPollException on error.

Examples

Example #1 A ZMQPoll example

Create a simple poll server

<?php

/* Create socket, request-reply pattern (reply socket) */
$context = new ZMQContext();
$server  = $context->getSocket(ZMQ::SOCKET_REP);

/* Bind to port 5555 on 127.0.0.1 */
$server->bind("tcp://127.0.0.1:5555");

/* Create new pollset for incoming/outgoing message */
$poll = new ZMQPoll();

/* Add the object and listen for poll in/out */
$id = $poll->add($server, ZMQ::POLL_IN | ZMQ::POLL_OUT);
echo "Added object with id " . $id . "\n";

/* Initialise readable and writable arrays */
$readable = array();
$writable = array();

while (true) {
   /* Amount of events retrieved */
   $events = 0;

   try {
       /* Poll until there is something to do */
       $events = $poll->poll($readable, $writable, -1);
       $errors = $poll->getLastErrors();

       if (count($errors) > 0) {
           foreach ($errors as $error) {
               echo "Error polling object " . $error . "\n";
           }
       }
   } catch (ZMQPollException $e) {
       echo "poll failed: " . $e->getMessage() . "\n";
   }

   if ($events > 0) {
       /* Loop through readable objects and recv messages */
       foreach ($readable as $r) {
           try {
               echo "Received message: " . $r->recv() . "\n";
           } catch (ZMQException $e) {
               echo "recv failed: " . $e->getMessage() . "\n";
           }
       }

       /* Loop through writable and send back messages */
       foreach ($writable as $w) {
           try {
               $w->send("Got it!");
           } catch (ZMQException $e) {
               echo "send failed: " . $e->getMessage() . "\n";
           }
       }
   }
}
?>