(PECL gearman >= 0.6.0)
GearmanClient::setDataCallback — Callback function when there is a data packet for a task
Sets the callback function for accepting data packets for a task. The callback function should take a single argument, a GearmanTask object.
callback
A function or method to call
如果成功則回傳 TRUE
,失敗則回傳 FALSE
。