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#ifndef RBIMPL_INTERN_SELECT_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_INTERN_SELECT_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.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.
* @brief Public APIs to provide ::rb_fd_select().
* @note Functions and structs defined in this header file are not
* necessarily ruby-specific. They don't need ::VALUE etc.
*/
#include "ruby/internal/config.h"
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h> /* for NFDBITS (BSD Net/2) */
#endif
#include "ruby/internal/dllexport.h"
/* thread.c */
#if defined(NFDBITS) && defined(HAVE_RB_FD_INIT)
# include "ruby/internal/intern/select/largesize.h"
#elif defined(_WIN32)
# include "ruby/internal/intern/select/win32.h"
# /** Does nothing (defined for compatibility). */
# define rb_fd_resize(n, f) ((void)(f))
#else
# include "ruby/internal/intern/select/posix.h"
# /** Does nothing (defined for compatibility). */
# define rb_fd_resize(n, f) ((void)(f))
#endif
RBIMPL_SYMBOL_EXPORT_BEGIN()
struct timeval;
/**
* 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.
*
* @param[in] nfds Max FD in everything passed, plus one.
* @param[in,out] rfds Set of FDs to wait for reads.
* @param[in,out] wfds Set of FDs to wait for writes.
* @param[in,out] efds Set of FDs to wait for OOBs.
* @param[in,out] timeout Max blocking duration.
* @retval -1 Failed, errno set.
* @retval 0 Timeout exceeded.
* @retval otherwise Total number of file descriptors returned.
* @post `rfds` contains readable FDs.
* @post `wfds` contains writable FDs.
* @post `efds` contains exceptional FDs.
* @post `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.
*
* @internal
*
* Although any file descriptors are possible here, it makes completely no
* sense to pass a descriptor that is not `O_NONBLOCK`. If you want to know
* the reason for this limitatuon in detail, you might find this thread super
* interesting: https://lkml.org/lkml/2004/10/6/117
*/
int rb_thread_fd_select(int nfds, rb_fdset_t *rfds, rb_fdset_t *wfds, rb_fdset_t *efds, struct timeval *timeout);
RBIMPL_SYMBOL_EXPORT_END()
#endif /* RBIMPL_INTERN_SELECT_H */
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