(PECL eio >= 0.0.1dev)
eio_cancel — Cancels a request
$req
   )
   eio_cancel() cancels a request specified by
   req
  
reqThe request resource
priThe request priority: EIO_PRI_DEFAULT, EIO_PRI_MIN, EIO_PRI_MAX, or NULL.
If NULL passed, pri internally is set to
EIO_PRI_DEFAULT.
callback
callback function is called when the request is done.
It should match the following prototype: 
void callback(mixed $data, int $result[, resource $req]);
datais custom data passed to the request.
resultrequest-specific result value; basically, the value returned by corresponding system call.
reqis optional request resource which can be used with functions like eio_get_last_error()
data
     Arbitrary variable passed to callback.
     
No value is returned.
Example #1 eio_cancel() example
<?php
 /* Is called when eio_nop() finished */
 function my_nop_cb($data, $result) {
  echo "my_nop ", $data, "\n";
 }
// This eio_nop() call will be cancelled
$req = eio_nop(EIO_PRI_DEFAULT, "my_nop_cb", "1");
var_dump($req);
eio_cancel($req);
// This time eio_nop() will be processed
eio_nop(EIO_PRI_DEFAULT, "my_nop_cb", "2");
// Process requests
eio_event_loop();
?>
The above example will output something similar to:
resource(4) of type (EIO Request Descriptor) my_nop 2