Issue #12328: Under Windows, refactor handling of Ctrl-C events and

make _multiprocessing.win32.WaitForMultipleObjects interruptible when
the wait_flag parameter is false.  Patch by sbt.

1 files changed, 20 insertions, 32 deletions

diff --git a/Modules/_multiprocessing/semaphore.c b/Modules/_multiprocessing/semaphore.c
index 6749f23..e48936e 100644
--- a/Modules/_multiprocessing/semaphore.c
+++ b/Modules/_multiprocessing/semaphore.c
@@ -62,7 +62,8 @@ semlock_acquire(SemLockObject *self, PyObject *args, PyObject *kwds)
     int blocking = 1;
     double timeout;
     PyObject *timeout_obj = Py_None;
-    DWORD res, full_msecs, msecs, start, ticks;
+    DWORD res, full_msecs, nhandles;
+    HANDLE handles[2], sigint_event;
 
     static char *kwlist[] = {"block", "timeout", NULL};
 
@@ -96,53 +97,40 @@ semlock_acquire(SemLockObject *self, PyObject *args, PyObject *kwds)
         Py_RETURN_TRUE;
     }
 
-    /* check whether we can acquire without blocking */
+    /* check whether we can acquire without releasing the GIL and blocking */
     if (WaitForSingleObject(self->handle, 0) == WAIT_OBJECT_0) {
         self->last_tid = GetCurrentThreadId();
         ++self->count;
         Py_RETURN_TRUE;
     }
 
-    msecs = full_msecs;
-    start = GetTickCount();
-
-    for ( ; ; ) {
-        HANDLE handles[2] = {self->handle, sigint_event};
+    /* prepare list of handles */
+    nhandles = 0;
+    handles[nhandles++] = self->handle;
+    if (_PyOS_IsMainThread()) {
+        sigint_event = _PyOS_SigintEvent();
+        assert(sigint_event != NULL);
+        handles[nhandles++] = sigint_event;
+    }
 
-        /* do the wait */
-        Py_BEGIN_ALLOW_THREADS
+    /* do the wait */
+    Py_BEGIN_ALLOW_THREADS
+    if (sigint_event != NULL)
         ResetEvent(sigint_event);
-        res = WaitForMultipleObjects(2, handles, FALSE, msecs);
-        Py_END_ALLOW_THREADS
-
-        /* handle result */
-        if (res != WAIT_OBJECT_0 + 1)
-            break;
-
-        /* got SIGINT so give signal handler a chance to run */
-        Sleep(1);
-
-        /* if this is main thread let KeyboardInterrupt be raised */
-        if (PyErr_CheckSignals())
-            return NULL;
-
-        /* recalculate timeout */
-        if (msecs != INFINITE) {
-            ticks = GetTickCount();
-            if ((DWORD)(ticks - start) >= full_msecs)
-                Py_RETURN_FALSE;
-            msecs = full_msecs - (ticks - start);
-        }
-    }
+    res = WaitForMultipleObjects(nhandles, handles, FALSE, full_msecs);
+    Py_END_ALLOW_THREADS
 
     /* handle result */
     switch (res) {
     case WAIT_TIMEOUT:
         Py_RETURN_FALSE;
-    case WAIT_OBJECT_0:
+    case WAIT_OBJECT_0 + 0:
         self->last_tid = GetCurrentThreadId();
         ++self->count;
         Py_RETURN_TRUE;
+    case WAIT_OBJECT_0 + 1:
+        errno = EINTR;
+        return PyErr_SetFromErrno(PyExc_IOError);
     case WAIT_FAILED:
         return PyErr_SetFromWindowsErr(0);
     default: