pythongh-125541: Make Ctrl-C interrupt threading.Lock.acquire() on Windows

colesbury · colesbury · commit 8b3e7ae88e23 · 2024-10-15T17:25:28.000Z
diff --git a/Doc/library/_thread.rst b/Doc/library/_thread.rst
@@ -187,6 +187,9 @@ Lock objects have the following methods:
    .. versionchanged:: 3.2
       Lock acquires can now be interrupted by signals on POSIX.
 
+   .. versionchanged:: 3.14
+      Lock acquires can now be interrupted by signals on Windows.
+
 
 .. method:: lock.release()
 
diff --git a/Misc/NEWS.d/next/Library/2024-10-15-16-50-03.gh-issue-125541.FfhmWo.rst b/Misc/NEWS.d/next/Library/2024-10-15-16-50-03.gh-issue-125541.FfhmWo.rst
@@ -0,0 +1,3 @@
+Pressing :kbd:`Ctrl-C` while blocked in :meth:`threading.Lock.acquire` now
+interrupts the function and raises a :exc:`KeyboardInterrupt` exception on
+Windows, similar to how it behaves on macOS and Linux.
diff --git a/Python/parking_lot.c b/Python/parking_lot.c
@@ -111,15 +111,26 @@ _PySemaphore_PlatformWait(_PySemaphore *sema, PyTime_t timeout)
             millis = (DWORD) div;
         }
     }
-    wait = WaitForSingleObjectEx(sema->platform_sem, millis, FALSE);
+
+    HANDLE sigint_event = _PyOS_SigintEvent();
+    HANDLE handles[2] = {sema->platform_sem, sigint_event};
+    // Only wait for the sigint_event if we are in the main thread
+    DWORD num_handles = _PyOS_IsMainThread() ? 2 : 1;
+    wait = WaitForMultipleObjectsEx(num_handles, handles, FALSE, millis, FALSE);
     if (wait == WAIT_OBJECT_0) {
         res = Py_PARK_OK;
     }
+    else if (wait == WAIT_OBJECT_0 + 1) {
+        ResetEvent(sigint_event);
+        res = Py_PARK_INTR;
+    }
     else if (wait == WAIT_TIMEOUT) {
         res = Py_PARK_TIMEOUT;
     }
     else {
-        res = Py_PARK_INTR;
+        _Py_FatalErrorFormat(__func__,
+            "unexpected error from semaphore: %u (error: %u)",
+            wait, GetLastError());
     }
 #elif defined(_Py_USE_SEMAPHORES)
     int err;

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	+Pressing :kbd:`Ctrl-C` while blocked in :meth:`threading.Lock.acquire` now
	`2`	+interrupts the function and raises a :exc:`KeyboardInterrupt` exception on
	`3`	`+Windows, similar to how it behaves on macOS and Linux.`
Original file line number	Diff line number	Diff line change
`@@ -111,15 +111,26 @@ _PySemaphore_PlatformWait(_PySemaphore *sema, PyTime_t timeout)`
`111`	`111`	`millis = (DWORD) div;`
`112`	`112`	`}`
`113`	`113`	`}`
`114`		`- wait = WaitForSingleObjectEx(sema->platform_sem, millis, FALSE);`
	`114`	`+`
	`115`	`+ HANDLE sigint_event = _PyOS_SigintEvent();`
	`116`	`+ HANDLE handles[2] = {sema->platform_sem, sigint_event};`
	`117`	`+ // Only wait for the sigint_event if we are in the main thread`
	`118`	`+ DWORD num_handles = _PyOS_IsMainThread() ? 2 : 1;`
	`119`	`+ wait = WaitForMultipleObjectsEx(num_handles, handles, FALSE, millis, FALSE);`
`115`	`120`	`if (wait == WAIT_OBJECT_0) {`
`116`	`121`	`res = Py_PARK_OK;`
`117`	`122`	`}`
	`123`	`+ else if (wait == WAIT_OBJECT_0 + 1) {`
	`124`	`+ ResetEvent(sigint_event);`
	`125`	`+ res = Py_PARK_INTR;`
	`126`	`+ }`
`118`	`127`	`else if (wait == WAIT_TIMEOUT) {`
`119`	`128`	`res = Py_PARK_TIMEOUT;`
`120`	`129`	`}`
`121`	`130`	`else {`
`122`		`- res = Py_PARK_INTR;`
	`131`	`+ _Py_FatalErrorFormat(__func__,`
	`132`	`+ "unexpected error from semaphore: %u (error: %u)",`
	`133`	`+ wait, GetLastError());`
`123`	`134`	`}`
`124`	`135`	`#elif defined(_Py_USE_SEMAPHORES)`
`125`	`136`	`int err;`