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Event callbacks

If a callback is registered for an event, it will be called when the event becomes active. To associate a callback with event one can pass a callable to either Event::__construct(), or Event::set(), or one of the factory methods like Event::timer().

An event callback should match the following prototype:

callback( mixed $fd = null , int $what = ?, mixed $arg = null ): void
fd

The file descriptor, stream resource or socket associated with the event. For signal event fd is equal to the signal number.

what

Bit mask of all events triggered.

arg

User custom data.

Event::timer() expects the callback to match the following prototype:

callback( mixed $arg = null ): void
arg

User custom data.

Event::signal() expects the callback to match the following prototype:

callback( int $signum = ?, mixed $arg = null ): void
signum

The number of the triggered signal(e.g. SIGTERM ).

arg

User custom data.