Improved EPOLLRDHUP handling. When it's known that the kernel supports EPOLLRDHUP, there is no need in additional recv() call to get EOF or error when the flag is absent in the event generated by the kernel. A special runtime test is done at startup to detect if EPOLLRDHUP is actually supported by the kernel because epoll_ctl() silently ignores unknown flags. With this knowledge it's now possible to drop the "ready" flag for partial read. Previously, the "ready" flag was kept until the recv() returned EOF or error. In particular, this change allows the lingering close heuristics (which relies on the "ready" flag state) to actually work on Linux, and not wait for more data in most cases. The "available" flag is now used in the read event with the semantics similar to the corresponding counter in kqueue.

/*
 * Copyright (C) Maxim Dounin
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_DLOPEN_H_INCLUDED_
#define _NGX_DLOPEN_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


#define ngx_dlopen(path)           dlopen((char *) path, RTLD_NOW | RTLD_GLOBAL)
#define ngx_dlopen_n               "dlopen()"

#define ngx_dlsym(handle, symbol)  dlsym(handle, symbol)
#define ngx_dlsym_n                "dlsym()"

#define ngx_dlclose(handle)        dlclose(handle)
#define ngx_dlclose_n              "dlclose()"


#if (NGX_HAVE_DLOPEN)
char *ngx_dlerror(void);
#endif


#endif /* _NGX_DLOPEN_H_INCLUDED_ */