Whenever you start an asynchronous operation, you will have to probe pq\Connection::poll() to determine the current status of the operation.
You can then use the public readonly property pq\Connection::$socket with stream_select() to wait for read/write-readiness.
NOTE: You cannot use the connection for anything else while an asynchronous operation is active.
First, you can establish or reset a connection asynchronously.
<?php
$c = new pq\Connection(null, pq\Connection::ASYNC);
?>
<?php
$c->resetAsync();
?>
Keep in mind that you have to test for write-readiness once before starting the polling loop on connect/reset.
<?php
// wait until the stream becomes writable
$w = array($c->socket);
$r = $e = null;
if (stream_select($r, $w, $e, null)) {
// loop until the connection is established
while (true) {
switch ($c->poll()) {
case pq\Connection::POLLING_READING:
// we should wait for the stream to be read-ready
$r = array($c->socket);
stream_select($r, $w, $e, NULL);
break;
case pq\Connection::POLLING_WRITING:
// we should wait for the stream to be write-ready
$w = array($c->socket);
$r = $e = null;
stream_select($r, $w, $e, null);
break;
case pq\Connection::POLLING_FAILED:
printf("Connection failed: %s\n", $c->errorMessage);
break 2;
case pq\Connection::POLLING_OK:
printf("Connection completed\n");
break 2;
}
}
}
?>
If you use an appropriate timeout in the stream_select() call and do something else at the end of the while loop, you probably got the idea...
<?php
$c = new pq\Connection;
$c->execAsync("SELECT 1+2+3; SELECT 2,3,4", function ($res) {
var_dump($res);
});
?>
The body of the while loop looks slightly different, when executing queries asynchronously, because you only have to wait for read-readiness.
You can use the public readonly property pq\Connection::$busy to test if a call to pq\Connection::getResult() would block, and if so wait for read-readiness and then call pq\Connection::poll().
<?php
do {
while ($c->busy) {
$r = array($c->socket);
$w = $e = null;
if (stream_select($r, $w, $e, null)) {
$c->poll();
}
}
} while ($c->getResult());
?>
If pq\Connection::getResult() returns NULL, there's nothing more in the pipeline.