view m4/signal_h.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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# signal_h.m4 serial 18
dnl Copyright (C) 2007-2012 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_SIGNAL_H],
[
  AC_REQUIRE([gl_SIGNAL_H_DEFAULTS])
  AC_REQUIRE([gl_CHECK_TYPE_SIGSET_T])
  gl_NEXT_HEADERS([signal.h])

# AIX declares sig_atomic_t to already include volatile, and C89 compilers
# then choke on 'volatile sig_atomic_t'.  C99 requires that it compile.
  AC_CHECK_TYPE([volatile sig_atomic_t], [],
    [HAVE_TYPE_VOLATILE_SIG_ATOMIC_T=0], [[
#include <signal.h>
    ]])

  dnl Ensure the type pid_t gets defined.
  AC_REQUIRE([AC_TYPE_PID_T])

  AC_REQUIRE([AC_TYPE_UID_T])

  dnl Persuade glibc <signal.h> to define sighandler_t.
  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
  AC_CHECK_TYPE([sighandler_t], [], [HAVE_SIGHANDLER_T=0], [[
#include <signal.h>
    ]])

  dnl Check for declarations of anything we want to poison if the
  dnl corresponding gnulib module is not in use.
  gl_WARN_ON_USE_PREPARE([[#include <signal.h>
    ]], [pthread_sigmask sigaction
    sigaddset sigdelset sigemptyset sigfillset sigismember
    sigpending sigprocmask])
])

AC_DEFUN([gl_CHECK_TYPE_SIGSET_T],
[
  AC_CHECK_TYPES([sigset_t],
    [gl_cv_type_sigset_t=yes], [gl_cv_type_sigset_t=no],
    [[
      #include <signal.h>
      /* Mingw defines sigset_t not in <signal.h>, but in <sys/types.h>.  */
      #include <sys/types.h>
    ]])
  if test $gl_cv_type_sigset_t != yes; then
    HAVE_SIGSET_T=0
  fi
])

AC_DEFUN([gl_SIGNAL_MODULE_INDICATOR],
[
  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
  AC_REQUIRE([gl_SIGNAL_H_DEFAULTS])
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
  dnl Define it also as a C macro, for the benefit of the unit tests.
  gl_MODULE_INDICATOR_FOR_TESTS([$1])
])

AC_DEFUN([gl_SIGNAL_H_DEFAULTS],
[
  GNULIB_PTHREAD_SIGMASK=0;    AC_SUBST([GNULIB_PTHREAD_SIGMASK])
  GNULIB_RAISE=0;              AC_SUBST([GNULIB_RAISE])
  GNULIB_SIGNAL_H_SIGPIPE=0;   AC_SUBST([GNULIB_SIGNAL_H_SIGPIPE])
  GNULIB_SIGPROCMASK=0;        AC_SUBST([GNULIB_SIGPROCMASK])
  GNULIB_SIGACTION=0;          AC_SUBST([GNULIB_SIGACTION])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_POSIX_SIGNALBLOCKING=1; AC_SUBST([HAVE_POSIX_SIGNALBLOCKING])
  HAVE_PTHREAD_SIGMASK=1;      AC_SUBST([HAVE_PTHREAD_SIGMASK])
  HAVE_RAISE=1;                AC_SUBST([HAVE_RAISE])
  HAVE_SIGSET_T=1;             AC_SUBST([HAVE_SIGSET_T])
  HAVE_SIGINFO_T=1;            AC_SUBST([HAVE_SIGINFO_T])
  HAVE_SIGACTION=1;            AC_SUBST([HAVE_SIGACTION])
  HAVE_STRUCT_SIGACTION_SA_SIGACTION=1;
                               AC_SUBST([HAVE_STRUCT_SIGACTION_SA_SIGACTION])
  HAVE_TYPE_VOLATILE_SIG_ATOMIC_T=1;
                               AC_SUBST([HAVE_TYPE_VOLATILE_SIG_ATOMIC_T])
  HAVE_SIGHANDLER_T=1;         AC_SUBST([HAVE_SIGHANDLER_T])
  REPLACE_PTHREAD_SIGMASK=0;   AC_SUBST([REPLACE_PTHREAD_SIGMASK])
  REPLACE_RAISE=0;             AC_SUBST([REPLACE_RAISE])
])