PHP Manual
Event
About buffer event callbacks

About buffer event callbacks

An object of EventBufferEvent class represents a buffer event . The asynchronous nature of I/O performed by Libevent implies that a socket(or other kind of file descriptor) is not always available. Event invokes corresponding callbacks when the resource becomes available for reading or writing, or when some event occurs(e.g. error, "end of line" etc.).

Read and write callbacks should match the following prototype:

callback( EventBufferEvent $bev = null , mixed $arg = null ): void

bev: Associated EventBufferEvent object.
arg: Custom variable attached to all callbacks via EventBufferEvent::__construct() , or EventBufferEvent::setCallbacks() .

Event callback should match the following prototype:

callback( EventBufferEvent $bev = null , int $events = 0 , mixed $arg = null ): void

bev: Associated EventBufferEvent object.
events: Bit mask of events: EventBufferEvent::READING , EventBufferEvent::WRITING , EventBufferEvent::EOL , EventBufferEvent::ERROR and EventBufferEvent::TIMEOUT . See EventBufferEvent constants
arg: Custom variable attached to all callbacks via EventBufferEvent::__construct() , or EventBufferEvent::setCallbacks() .