I am trying to understand which logging object should be used in Nginx modules. For e.g. in this same method, at some places I see ngx_cycle->log, at other places event->log or c->log. What is the right way to choose this?

With all of them the logs do show up in the log file though.

As you can see here this is the second argument to function ngx_log_error_core and its type is ngx_log_t*.

I read about the cycle but it's still not clear.