These days I have been busy studying the source of the nginx. I finished the part of master process and of the work process. At once the channel object is understood, and take a look at the event object.
The event system in the nginx is complicated. It consisted of three components. One is the siganl in linux, or some unix else; second is the command between the processes; last is some global flag variables, which tell processes the status of nginx. There may be more. It need more study.
Due to the module technique in the nginx it is unhappy to read codes. It is not easy to find some functions you need. Some function have multi-version varying from different operation systems, or varying from the net or IO technique.
I had tried make a figure about the calling relation of functions in the nginx, which is a panorama. But I failed. I am not familiar with those tools. The operating step is also strange. At the same time, the complie script of the nginx is too restrict to revise it.