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:

void callback ([ mixed $fd = NULL [, int $what [, mixed $arg = NULL ]]] )

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:

void callback ([ mixed $arg = NULL ] )

arg
User custom data.

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

void callback ([ int $signum [, mixed $arg = NULL ]] )

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

arg
User custom data.