select.h File Reference

Public APIs to provide rb_fd_select(). More...

#include "ruby/internal/config.h"
#include "ruby/internal/dllexport.h"
#include "ruby/internal/intern/select/posix.h"

Go to the source code of this file.

Macros
#define	rb_fd_resize(n, f)
	Does nothing (defined for compatibility).

Functions
int	rb_thread_fd_select (int nfds, rb_fdset_t *rfds, rb_fdset_t *wfds, rb_fdset_t *efds, struct timeval *timeout)
	Waits for multiple file descriptors at once.

Detailed Description

Public APIs to provide rb_fd_select().

Author

Ruby developers ruby-.nosp@m.core.nosp@m.@ruby.nosp@m.-lan.nosp@m.g.org

Copyright

This file is a part of the programming language Ruby. Permission is hereby granted, to either redistribute and/or modify this file, provided that the conditions mentioned in the file COPYING are met. Consult the file for details.

Warning

Symbols prefixed with either RBIMPL or rbimpl are implementation details. Don't take them as canon. They could rapidly appear then vanish. The name (path) of this header file is also an implementation detail. Do not expect it to persist at the place it is now. Developers are free to move it anywhere anytime at will.

Note

To ruby-core: remember that this header can be possibly recursively included from extension libraries written in C++. Do not expect for instance __VA_ARGS__ is always available. We assume C99 for ruby itself but we don't assume languages of extension libraries. They could be written in C++98.

Functions and structs defined in this header file are not necessarily ruby-specific. They don't need VALUE etc.

Definition in file select.h.

Macro Definition Documentation

rb_fd_resize

#define rb_fd_resize	(		n,
			f )

Value:

((void)(f))

Does nothing (defined for compatibility).

Definition at line 43 of file select.h.

Function Documentation

rb_thread_fd_select()

int rb_thread_fd_select	(	int	nfds,
		rb_fdset_t *	rfds,
		rb_fdset_t *	wfds,
		rb_fdset_t *	efds,
		struct timeval *	timeout )

Waits for multiple file descriptors at once.

This is basically a wrapper of system-provided select() with releasing GVL, to allow other Ruby threads run in parallel.

Parameters

[in]	nfds	Max FD in everything passed, plus one.
[in,out]	rfds	Set of FDs to wait for reads.
[in,out]	wfds	Set of FDs to wait for writes.
[in,out]	efds	Set of FDs to wait for OOBs.
[in,out]	timeout	Max blocking duration.

Return values

-1	Failed, errno set.
0	Timeout exceeded.
otherwise	Total number of file descriptors returned.

Postcondition

rfds contains readable FDs.

wfds contains writable FDs.

efds contains exceptional FDs.

timeout is the time left.

Note

All pointers are allowed to be null pointers.

Although backend threads can run in parallel of this function, touching a file descriptor from multiple threads could be problematic. For instance what happens when a thread closes a file descriptor that is selected by someone else, vastly varies among operating systems. You would better avoid touching an fd from more than one threads.

NOTE: this function is used in native extensions, so change its API with care.

Definition at line 4546 of file thread.c.

Referenced by rb_thread_fd_select().