[libvirt] the arguments of qemudDispatchServerEvent

Hi all: I am now reading the source codes of libvirt with version 0.9.2 , and be stuck by the function "qemudDispatchServerEvent". as you can see: static void qemudDispatchServerEvent(int watch, int fd, int events, void *opaque) { ... } My question is : except for the argument "void *opaque"， when and how the other three arguments (int watch, int fd, int events) being incoming ? For it is a static function, I look through the source file "libvirt.c" and find no answer . Could someone give me a help ? Thanks a lot. Yours. mzawdx