(PECL ev >= 0.2.0)
Ev::nowUpdate — Establishes the current time by querying the kernel, updating the time returned by Ev::now in the progress.
Establishes the current time by querying the kernel, updating the time returned by Ev::now() in the progress. This is a costly operation and is usually done automatically within Ev::run() .
This method is rarely useful, but when some event callback runs for a very long time without entering the event loop, updating libev 's consideration of the current time is a good idea.
此函数没有参数。
没有返回值。