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authorHavoc Pennington <hp@redhat.com>2006-10-27 03:29:09 +0000
committerHavoc Pennington <hp@redhat.com>2006-10-27 03:29:09 +0000
commitfbfec98d0f3ad5232dd6cbd63acbdd008acf2578 (patch)
treeb75abe38d04d3b11ce375bf441ed8eef07b016b1 /dbus/dbus-sysdeps-pthread.c
parentbdbbf46ca88ac43bec9c36909990730d102983c5 (diff)
2006-10-26 Havoc Pennington <hp@redhat.com>
* dbus/dbus-sysdeps-pthread.c (_dbus_pthread_mutex_lock): change to be recursive (_dbus_pthread_mutex_unlock): make it recursive (_dbus_pthread_condvar_wait): save/restore the recursion count (_dbus_pthread_condvar_wait_timeout): save/restore the recursion count
Diffstat (limited to 'dbus/dbus-sysdeps-pthread.c')
-rw-r--r--dbus/dbus-sysdeps-pthread.c111
1 files changed, 93 insertions, 18 deletions
diff --git a/dbus/dbus-sysdeps-pthread.c b/dbus/dbus-sysdeps-pthread.c
index 0b9c5913..9979283b 100644
--- a/dbus/dbus-sysdeps-pthread.c
+++ b/dbus/dbus-sysdeps-pthread.c
@@ -31,6 +31,8 @@
typedef struct {
pthread_mutex_t lock;
+ int count;
+ pthread_t holder;
} DBusMutexPThread;
typedef struct {
@@ -74,6 +76,14 @@ _dbus_pthread_mutex_new (void)
PTHREAD_CHECK ("pthread_mutex_init", result);
}
+ /* Only written */
+ pmutex->count = 0;
+
+ /* There's no portable way to have a "null" pthread afaik so we
+ * can't set pmutex->holder to anything sensible. We only access it
+ * once the lock is held (which means we've set it).
+ */
+
return DBUS_MUTEX (pmutex);
}
@@ -81,30 +91,77 @@ static void
_dbus_pthread_mutex_free (DBusMutex *mutex)
{
DBusMutexPThread *pmutex = DBUS_MUTEX_PTHREAD (mutex);
+
+ _dbus_assert (pmutex->count == 0);
PTHREAD_CHECK ("pthread_mutex_destroy", pthread_mutex_destroy (&pmutex->lock));
dbus_free (pmutex);
}
-static dbus_bool_t
+static void
_dbus_pthread_mutex_lock (DBusMutex *mutex)
{
DBusMutexPThread *pmutex = DBUS_MUTEX_PTHREAD (mutex);
-
- PTHREAD_CHECK ("pthread_mutex_lock", pthread_mutex_lock (&pmutex->lock));
-
- return TRUE;
+ pthread_t self = pthread_self ();
+
+ /* If the count is > 0 then someone had the lock, maybe us. If it is
+ * 0, then it might immediately change right after we read it,
+ * but it will be changed by another thread; i.e. if we read 0,
+ * we assume that this thread doesn't have the lock.
+ *
+ * Not 100% sure this is safe, but ... seems like it should be.
+ */
+ if (pmutex->count == 0)
+ {
+ /* We know we don't have the lock; someone may have the lock. */
+
+ PTHREAD_CHECK ("pthread_mutex_lock", pthread_mutex_lock (&pmutex->lock));
+
+ /* We now have the lock. Count must be 0 since it was before when we
+ * did not have the lock, and we have not changed it in this thread.
+ */
+ _dbus_assert (pmutex->count == 0);
+
+ pmutex->holder = self;
+ pmutex->count = 1;
+ }
+ else
+ {
+ /* We know someone had the lock, possibly us. Thus
+ * pmutex->holder is not pointing to junk, though it may not be
+ * the lock holder anymore if the lock holder is not us.
+ * If the lock holder is us, then we definitely have the lock.
+ */
+
+ if (pthread_equal (pmutex->holder, self))
+ {
+ /* We already have the lock. */
+ }
+ else
+ {
+ /* Wait for the lock */
+ PTHREAD_CHECK ("pthread_mutex_lock", pthread_mutex_lock (&pmutex->lock));
+ _dbus_assert (pmutex->count == 0);
+ }
+
+ pmutex->count += 1;
+ }
}
-static dbus_bool_t
+static void
_dbus_pthread_mutex_unlock (DBusMutex *mutex)
{
DBusMutexPThread *pmutex = DBUS_MUTEX_PTHREAD (mutex);
- PTHREAD_CHECK ("pthread_mutex_unlock", pthread_mutex_unlock (&pmutex->lock));
+ _dbus_assert (pmutex->count > 0);
+
+ pmutex->count -= 1;
- return TRUE;
+ if (pmutex->count == 0)
+ PTHREAD_CHECK ("pthread_mutex_unlock", pthread_mutex_unlock (&pmutex->lock));
+
+ /* We leave pmutex->holder set to ourselves, its content is undefined if count is 0 */
}
static DBusCondVar *
@@ -148,8 +205,16 @@ _dbus_pthread_condvar_wait (DBusCondVar *cond,
{
DBusMutexPThread *pmutex = DBUS_MUTEX_PTHREAD (mutex);
DBusCondVarPThread *pcond = DBUS_COND_VAR_PTHREAD (cond);
+ int old_count;
+ _dbus_assert (pmutex->count > 0);
+ _dbus_assert (pthread_equal (pmutex->holder, pthread_self ()));
+
+ old_count = pmutex->count;
+ pmutex->count = 0;
PTHREAD_CHECK ("pthread_cond_wait", pthread_cond_wait (&pcond->cond, &pmutex->lock));
+ _dbus_assert (pmutex->count == 0);
+ pmutex->count = old_count;
}
static dbus_bool_t
@@ -162,6 +227,10 @@ _dbus_pthread_condvar_wait_timeout (DBusCondVar *cond,
struct timeval time_now;
struct timespec end_time;
int result;
+ int old_count;
+
+ _dbus_assert (pmutex->count > 0);
+ _dbus_assert (pthread_equal (pmutex->holder, pthread_self ()));
gettimeofday (&time_now, NULL);
@@ -173,12 +242,17 @@ _dbus_pthread_condvar_wait_timeout (DBusCondVar *cond,
end_time.tv_nsec -= 1000*1000*1000;
}
+ old_count = pmutex->count;
+ pmutex->count = 0;
result = pthread_cond_timedwait (&pcond->cond, &pmutex->lock, &end_time);
-
+
if (result != ETIMEDOUT)
{
PTHREAD_CHECK ("pthread_cond_timedwait", result);
}
+
+ _dbus_assert (pmutex->count == 0);
+ pmutex->count = old_count;
/* return true if we did not time out */
return result != ETIMEDOUT;
@@ -202,26 +276,27 @@ _dbus_pthread_condvar_wake_all (DBusCondVar *cond)
static const DBusThreadFunctions pthread_functions =
{
- DBUS_THREAD_FUNCTIONS_MUTEX_NEW_MASK |
- DBUS_THREAD_FUNCTIONS_MUTEX_FREE_MASK |
- DBUS_THREAD_FUNCTIONS_MUTEX_LOCK_MASK |
- DBUS_THREAD_FUNCTIONS_MUTEX_UNLOCK_MASK |
+ DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_NEW_MASK |
+ DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_FREE_MASK |
+ DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_LOCK_MASK |
+ DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_UNLOCK_MASK |
DBUS_THREAD_FUNCTIONS_CONDVAR_NEW_MASK |
DBUS_THREAD_FUNCTIONS_CONDVAR_FREE_MASK |
DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_MASK |
DBUS_THREAD_FUNCTIONS_CONDVAR_WAIT_TIMEOUT_MASK |
DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ONE_MASK|
DBUS_THREAD_FUNCTIONS_CONDVAR_WAKE_ALL_MASK,
- _dbus_pthread_mutex_new,
- _dbus_pthread_mutex_free,
- _dbus_pthread_mutex_lock,
- _dbus_pthread_mutex_unlock,
+ NULL, NULL, NULL, NULL,
_dbus_pthread_condvar_new,
_dbus_pthread_condvar_free,
_dbus_pthread_condvar_wait,
_dbus_pthread_condvar_wait_timeout,
_dbus_pthread_condvar_wake_one,
- _dbus_pthread_condvar_wake_all
+ _dbus_pthread_condvar_wake_all,
+ _dbus_pthread_mutex_new,
+ _dbus_pthread_mutex_free,
+ _dbus_pthread_mutex_lock,
+ _dbus_pthread_mutex_unlock
};
dbus_bool_t