From ae24bb35e2ee3ecde990f55852982b573754ec43 Mon Sep 17 00:00:00 2001 From: Colin Walters Date: Fri, 10 Jul 2009 22:27:55 -0400 Subject: Bug 18121 - Use a monotonic clock for pthread timeouts Patch based on one from Keith Mok , some followup work from Janne Karhunen . We don't want condition variable timeouts to be affected by the system clock. Use the POSIX CLOCK_MONOTONIC if available. --- dbus/dbus-sysdeps-pthread.c | 43 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 41 insertions(+), 2 deletions(-) (limited to 'dbus') diff --git a/dbus/dbus-sysdeps-pthread.c b/dbus/dbus-sysdeps-pthread.c index b7c37066..46e4204d 100644 --- a/dbus/dbus-sysdeps-pthread.c +++ b/dbus/dbus-sysdeps-pthread.c @@ -33,6 +33,15 @@ #include #endif +#include + +/* Whether we have a "monotonic" clock; i.e. a clock not affected by + * changes in system time. + * This is initialized once in check_monotonic_clock below. + * https://bugs.freedesktop.org/show_bug.cgi?id=18121 + */ +static dbus_bool_t have_monotonic_clock = 0; + typedef struct { pthread_mutex_t lock; /**< lock protecting count field */ volatile int count; /**< count of how many times lock holder has recursively locked */ @@ -184,13 +193,21 @@ static DBusCondVar * _dbus_pthread_condvar_new (void) { DBusCondVarPThread *pcond; + pthread_condattr_t attr; int result; pcond = dbus_new (DBusCondVarPThread, 1); if (pcond == NULL) return NULL; - result = pthread_cond_init (&pcond->cond, NULL); + pthread_condattr_init (&attr); +#ifdef HAVE_MONOTONIC_CLOCK + if (have_monotonic_clock) + pthread_condattr_setclock (&attr, CLOCK_MONOTONIC); +#endif + + result = pthread_cond_init (&pcond->cond, &attr); + pthread_condattr_destroy (&attr); if (result == EAGAIN || result == ENOMEM) { @@ -248,7 +265,18 @@ _dbus_pthread_condvar_wait_timeout (DBusCondVar *cond, _dbus_assert (pmutex->count > 0); _dbus_assert (pthread_equal (pmutex->holder, pthread_self ())); - + +#ifdef HAVE_MONOTONIC_CLOCK + if (have_monotonic_clock) + { + struct timespec monotonic_timer; + clock_gettime (CLOCK_MONOTONIC,&monotonic_timer); + time_now.tv_sec = monotonic_timer.tv_sec; + time_now.tv_usec = monotonic_timer.tv_nsec / 1000; + } + else + /* This else falls through to gettimeofday */ +#endif gettimeofday (&time_now, NULL); end_time.tv_sec = time_now.tv_sec + timeout_milliseconds / 1000; @@ -317,8 +345,19 @@ static const DBusThreadFunctions pthread_functions = _dbus_pthread_mutex_unlock }; +static void +check_monotonic_clock (void) +{ +#ifdef HAVE_MONOTONIC_CLOCK + struct timespec dummy; + if (clock_getres (CLOCK_MONOTONIC, &dummy) == 0) + have_monotonic_clock = TRUE; +#endif +} + dbus_bool_t _dbus_threads_init_platform_specific (void) { + check_monotonic_clock (); return dbus_threads_init (&pthread_functions); } -- cgit