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view m4/wctob.m4 @ 16869:38e6d30d7e4d
poll/select: prevent busy-waiting
2012-05-21 Paolo Bonzini <bonzini@gnu.org>
poll/select: prevent busy-waiting. SwitchToThread() only gives away
the rest of the current time slice to another thread in the current
process. So if the thread that feeds the file decscriptor we're
polling is not in the current process, we get busy-waiting.
* lib/poll.c: Use SleepEx(1, TRUE) instead of SwitchToThread().
Patch from Theodore Leblond.
* lib/select.c: Split polling out of the loop that sets the output
fd_sets. Check for zero result and loop if the wait timeout is
infinite.
author | Paolo Bonzini <bonzini@gnu.org> |
---|---|
date | Mon, 21 May 2012 09:52:42 +0200 |
parents | 8250f2777afc |
children | e542fd46ad6f |
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# wctob.m4 serial 10 dnl Copyright (C) 2008-2012 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. AC_DEFUN([gl_FUNC_WCTOB], [ AC_REQUIRE([gl_WCHAR_H_DEFAULTS]) AC_CHECK_FUNCS_ONCE([wctob]) if test $ac_cv_func_wctob = no; then HAVE_WCTOB=0 HAVE_DECL_WCTOB=0 else HAVE_WCTOB=1 dnl Solaris 9 has the wctob() function but it does not work. dnl Cygwin 1.7.2 has the wctob() function but it clobbers caller-owned dnl registers, see <http://cygwin.com/ml/cygwin/2010-05/msg00015.html>. AC_REQUIRE([AC_PROG_CC]) AC_REQUIRE([gt_LOCALE_FR]) AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles AC_CACHE_CHECK([whether wctob works], [gl_cv_func_wctob_works], [ dnl Initial guess, used when cross-compiling or when no suitable locale dnl is present. changequote(,)dnl case "$host_os" in # Guess no on Solaris <= 9 and Cygwin. solaris2.[1-9] | solaris2.[1-9].* | cygwin*) gl_cv_func_wctob_works="guessing no" ;; # Guess yes otherwise. *) gl_cv_func_wctob_works="guessing yes" ;; esac changequote([,])dnl case "$host_os" in cygwin*) AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #include <locale.h> /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before <wchar.h>. BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included before <wchar.h>. */ #include <stddef.h> #include <stdio.h> #include <time.h> #include <wchar.h> register long global __asm__ ("%ebx"); int main () { setlocale (LC_ALL, "en_US.UTF-8"); global = 0x12345678; if (wctob (0x00FC) != -1) return 1; if (global != 0x12345678) return 2; return 0; }]])], [:], [gl_cv_func_wctob_works=no], [:]) ;; esac if test "$gl_cv_func_wctob_works" != no && test $LOCALE_FR != none; then AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #include <locale.h> #include <string.h> /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before <wchar.h>. BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included before <wchar.h>. */ #include <stddef.h> #include <stdio.h> #include <time.h> #include <wchar.h> int main () { if (setlocale (LC_ALL, "$LOCALE_FR") != NULL) { wchar_t wc; if (mbtowc (&wc, "\374", 1) == 1) if (wctob (wc) != (unsigned char) '\374') return 1; } return 0; }]])], [gl_cv_func_wctob_works=yes], [gl_cv_func_wctob_works=no], [:]) fi ]) case "$gl_cv_func_wctob_works" in *yes) ;; *) REPLACE_WCTOB=1 ;; esac if test $REPLACE_WCTOB = 0; then dnl IRIX 6.5 has the wctob() function but does not declare it. AC_CHECK_DECLS([wctob], [], [], [[ /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before <wchar.h>. BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included before <wchar.h>. */ #include <stddef.h> #include <stdio.h> #include <time.h> #include <wchar.h> ]]) if test $ac_cv_have_decl_wctob != yes; then HAVE_DECL_WCTOB=0 fi fi fi ]) # Prerequisites of lib/wctob.c. AC_DEFUN([gl_PREREQ_WCTOB], [ : ])