Issue #8844: Regular and recursive lock acquisitions can now be interrupted
by signals on platforms using pthreads. Patch by Reid Kleckner.
diff --git a/Python/thread_nt.h b/Python/thread_nt.h
index 9de9e0d..684b545 100644
--- a/Python/thread_nt.h
+++ b/Python/thread_nt.h
@@ -238,10 +238,13 @@
* and 0 if the lock was not acquired. This means a 0 is returned
* if the lock has already been acquired by this thread!
*/
-int
-PyThread_acquire_lock_timed(PyThread_type_lock aLock, PY_TIMEOUT_T microseconds)
+PyLockStatus
+PyThread_acquire_lock_timed(PyThread_type_lock aLock,
+ PY_TIMEOUT_T microseconds, int intr_flag)
{
- int success ;
+ /* Fow now, intr_flag does nothing on Windows, and lock acquires are
+ * uninterruptible. */
+ PyLockStatus success;
PY_TIMEOUT_T milliseconds;
if (microseconds >= 0) {
@@ -258,7 +261,13 @@
dprintf(("%ld: PyThread_acquire_lock_timed(%p, %lld) called\n",
PyThread_get_thread_ident(), aLock, microseconds));
- success = aLock && EnterNonRecursiveMutex((PNRMUTEX) aLock, (DWORD) milliseconds) == WAIT_OBJECT_0 ;
+ if (aLock && EnterNonRecursiveMutex((PNRMUTEX)aLock,
+ (DWORD)milliseconds) == WAIT_OBJECT_0) {
+ success = PY_LOCK_ACQUIRED;
+ }
+ else {
+ success = PY_LOCK_FAILURE;
+ }
dprintf(("%ld: PyThread_acquire_lock(%p, %lld) -> %d\n",
PyThread_get_thread_ident(), aLock, microseconds, success));
@@ -268,7 +277,7 @@
int
PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)
{
- return PyThread_acquire_lock_timed(aLock, waitflag ? -1 : 0);
+ return PyThread_acquire_lock_timed(aLock, waitflag ? -1 : 0, 0);
}
void
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index c007c8b..ffc791c 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -316,16 +316,17 @@
return (status == -1) ? errno : status;
}
-int
-PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds)
+PyLockStatus
+PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds,
+ int intr_flag)
{
- int success;
+ PyLockStatus success;
sem_t *thelock = (sem_t *)lock;
int status, error = 0;
struct timespec ts;
- dprintf(("PyThread_acquire_lock_timed(%p, %lld) called\n",
- lock, microseconds));
+ dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) called\n",
+ lock, microseconds, intr_flag));
if (microseconds > 0)
MICROSECONDS_TO_TIMESPEC(microseconds, ts);
@@ -336,33 +337,38 @@
status = fix_status(sem_trywait(thelock));
else
status = fix_status(sem_wait(thelock));
- } while (status == EINTR); /* Retry if interrupted by a signal */
+ /* Retry if interrupted by a signal, unless the caller wants to be
+ notified. */
+ } while (!intr_flag && status == EINTR);
- if (microseconds > 0) {
- if (status != ETIMEDOUT)
- CHECK_STATUS("sem_timedwait");
- }
- else if (microseconds == 0) {
- if (status != EAGAIN)
- CHECK_STATUS("sem_trywait");
- }
- else {
- CHECK_STATUS("sem_wait");
+ /* Don't check the status if we're stopping because of an interrupt. */
+ if (!(intr_flag && status == EINTR)) {
+ if (microseconds > 0) {
+ if (status != ETIMEDOUT)
+ CHECK_STATUS("sem_timedwait");
+ }
+ else if (microseconds == 0) {
+ if (status != EAGAIN)
+ CHECK_STATUS("sem_trywait");
+ }
+ else {
+ CHECK_STATUS("sem_wait");
+ }
}
- success = (status == 0) ? 1 : 0;
+ if (status == 0) {
+ success = PY_LOCK_ACQUIRED;
+ } else if (intr_flag && status == EINTR) {
+ success = PY_LOCK_INTR;
+ } else {
+ success = PY_LOCK_FAILURE;
+ }
- dprintf(("PyThread_acquire_lock_timed(%p, %lld) -> %d\n",
- lock, microseconds, success));
+ dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) -> %d\n",
+ lock, microseconds, intr_flag, success));
return success;
}
-int
-PyThread_acquire_lock(PyThread_type_lock lock, int waitflag)
-{
- return PyThread_acquire_lock_timed(lock, waitflag ? -1 : 0);
-}
-
void
PyThread_release_lock(PyThread_type_lock lock)
{
@@ -436,21 +442,25 @@
free((void *)thelock);
}
-int
-PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds)
+PyLockStatus
+PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds,
+ int intr_flag)
{
- int success;
+ PyLockStatus success;
pthread_lock *thelock = (pthread_lock *)lock;
int status, error = 0;
- dprintf(("PyThread_acquire_lock_timed(%p, %lld) called\n",
- lock, microseconds));
+ dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) called\n",
+ lock, microseconds, intr_flag));
status = pthread_mutex_lock( &thelock->mut );
CHECK_STATUS("pthread_mutex_lock[1]");
- success = thelock->locked == 0;
- if (!success && microseconds != 0) {
+ if (thelock->locked == 0) {
+ success = PY_LOCK_ACQUIRED;
+ } else if (microseconds == 0) {
+ success = PY_LOCK_FAILURE;
+ } else {
struct timespec ts;
if (microseconds > 0)
MICROSECONDS_TO_TIMESPEC(microseconds, ts);
@@ -458,7 +468,8 @@
/* mut must be locked by me -- part of the condition
* protocol */
- while (thelock->locked) {
+ success = PY_LOCK_FAILURE;
+ while (success == PY_LOCK_FAILURE) {
if (microseconds > 0) {
status = pthread_cond_timedwait(
&thelock->lock_released,
@@ -473,25 +484,30 @@
&thelock->mut);
CHECK_STATUS("pthread_cond_wait");
}
+
+ if (intr_flag && status == 0 && thelock->locked) {
+ /* We were woken up, but didn't get the lock. We probably received
+ * a signal. Return PY_LOCK_INTR to allow the caller to handle
+ * it and retry. */
+ success = PY_LOCK_INTR;
+ break;
+ } else if (status == 0 && !thelock->locked) {
+ success = PY_LOCK_ACQUIRED;
+ } else {
+ success = PY_LOCK_FAILURE;
+ }
}
- success = (status == 0);
}
- if (success) thelock->locked = 1;
+ if (success == PY_LOCK_ACQUIRED) thelock->locked = 1;
status = pthread_mutex_unlock( &thelock->mut );
CHECK_STATUS("pthread_mutex_unlock[1]");
- if (error) success = 0;
- dprintf(("PyThread_acquire_lock_timed(%p, %lld) -> %d\n",
- lock, microseconds, success));
+ if (error) success = PY_LOCK_FAILURE;
+ dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) -> %d\n",
+ lock, microseconds, intr_flag, success));
return success;
}
-int
-PyThread_acquire_lock(PyThread_type_lock lock, int waitflag)
-{
- return PyThread_acquire_lock_timed(lock, waitflag ? -1 : 0);
-}
-
void
PyThread_release_lock(PyThread_type_lock lock)
{
@@ -515,6 +531,12 @@
#endif /* USE_SEMAPHORES */
+int
+PyThread_acquire_lock(PyThread_type_lock lock, int waitflag)
+{
+ return PyThread_acquire_lock_timed(lock, waitflag ? -1 : 0, /*intr_flag=*/0);
+}
+
/* set the thread stack size.
* Return 0 if size is valid, -1 if size is invalid,
* -2 if setting stack size is not supported.