The Event class

(PECL event >= 1.2.6-beta)

Introduction

Event class represents and event firing on a file descriptor being ready to read from or write to; a file descriptor becoming ready to read from or write to(edge-triggered I/O only); a timeout expiring; a signal occurring; a user-triggered event.

Every event is associated with EventBase . However, event will never fire until it is added (via Event::add() ). An added event remains in pending state until the registered event occurs, thus turning it to active state. To handle events user may register a callback which is called when event becomes active. If event is configured persistent , it remains pending. If it is not persistent, it stops being pending when it's callback runs. Event::del() method deletes event, thus making it non-pending. By means of Event::add() method it could be added again.

Class synopsis

final class Event {

/* Constants */

const int ET = 32;

const int PERSIST = 16;

const int READ = 2;

const int WRITE = 4;

const int SIGNAL = 8;

const int TIMEOUT = 1;

/* Properties */

public readonly bool $pending;

/* Methods */

public add( float $timeout = ?): bool

public __construct(
     EventBase $base ,
     mixed $fd ,
     int $what ,
     callable $cb ,
     mixed $arg = NULL
)

public del(): bool

public free(): void

public static getSupportedMethods(): array

public pending( int $flags ): bool

public set(
     EventBase $base ,
     mixed $fd ,
     int $what = ?,
     callable $cb = ?,
     mixed $arg = ?
): bool

public setPriority( int $priority ): bool

public setTimer( EventBase $base , callable $cb , mixed $arg = ?): bool

public static signal(
     EventBase $base ,
     int $signum ,
     callable $cb ,
     mixed $arg = ?
): Event

public static timer( EventBase $base , callable $cb , mixed $arg = ?): Event

}

Properties

pending: Whether event is pending. See About event persistence .

Predefined Constants

Event::ET

Indicates that the event should be edge-triggered, if the underlying event base backend supports edge-triggered events. This affects the semantics of Event::READ and Event::WRITE .

Event::PERSIST

Indicates that the event is persistent. See About event persistence .

Event::READ

This flag indicates an event that becomes active when the provided file descriptor(usually a stream resource, or socket) is ready for reading.

Event::WRITE

This flag indicates an event that becomes active when the provided file descriptor(usually a stream resource, or socket) is ready for reading.

Event::SIGNAL

Used to implement signal detection. See "Constructing signal events" below.

Event::TIMEOUT

This flag indicates an event that becomes active after a timeout elapses.

The Event::TIMEOUT flag is ignored when constructing an event: one can either set a timeout when event is added , or not. It is set in the $what argument to the callback function when a timeout has occurred.

Event::add — Makes event pending
Event::addSignal — Alias of Event::add
Event::addTimer — Alias of Event::add
Event::__construct — Constructs Event object
Event::del — Makes event non-pending
Event::delSignal — Alias of Event::del
Event::delTimer — Alias of Event::del
Event::free — Make event non-pending and free resources allocated for this event
Event::getSupportedMethods — Returns array with of the names of the methods supported in this version of Libevent
Event::pending — Detects whether event is pending or scheduled
Event::set — Re-configures event
Event::setPriority — Set event priority
Event::setTimer — Re-configures timer event
Event::signal — Constructs signal event object
Event::timer — Constructs timer event object