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.

Include/intrcheck.h

@@ -8,6 +8,12 @@ extern "C" {
PyAPI_FUNC(int) PyOS_InterruptOccurred(void);
PyAPI_FUNC(void) PyOS_InitInterrupts(void);
PyAPI_FUNC(void) PyOS_AfterFork(void);
PyAPI_FUNC(int) _PyOS_IsMainThread(void);

#ifdef MS_WINDOWS
/* windows.h is not included by Python.h so use void* instead of HANDLE */
PyAPI_FUNC(void*) _PyOS_SigintEvent(void);
#endif

#ifdef __cplusplus
}

Misc/NEWS

@@ -387,6 +387,10 @@ Core and Builtins
Library
-------

- 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.

- Issue #13322: Fix BufferedWriter.write() to ensure that BlockingIOError is
  raised when the wrapped raw file is non-blocking and the write would block.
  Previous code assumed that the raw write() would raise BlockingIOError, but

Modules/_multiprocessing/multiprocessing.c

@@ -53,30 +53,6 @@ mp_SetError(PyObject *Type, int num)
}


/*
 * Windows only
 */

#ifdef MS_WINDOWS

/* On Windows we set an event to signal Ctrl-C; compare with timemodule.c */

HANDLE sigint_event = NULL;

static BOOL WINAPI
ProcessingCtrlHandler(DWORD dwCtrlType)
{
    SetEvent(sigint_event);
    return FALSE;
}

#endif /* MS_WINDOWS */


/*
 * All platforms
 */

static PyObject*
multiprocessing_address_of_buffer(PyObject *self, PyObject *obj)
{
@@ -165,17 +141,6 @@ PyInit__multiprocessing(void)
    if (!temp)
        return NULL;
    PyModule_AddObject(module, "win32", temp);

    /* Initialize the event handle used to signal Ctrl-C */
    sigint_event = CreateEvent(NULL, TRUE, FALSE, NULL);
    if (!sigint_event) {
        PyErr_SetFromWindowsErr(0);
        return NULL;
    }
    if (!SetConsoleCtrlHandler(ProcessingCtrlHandler, TRUE)) {
        PyErr_SetFromWindowsErr(0);
        return NULL;
    }
#endif

    /* Add configuration macros */

Modules/_multiprocessing/multiprocessing.h

@@ -100,7 +100,6 @@ PyObject *mp_SetError(PyObject *Type, int num);
extern PyObject *BufferTooShort;
extern PyTypeObject SemLockType;
extern PyTypeObject PipeConnectionType;
extern HANDLE sigint_event;

/*
 * Miscellaneous

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:

Modules/_multiprocessing/win32_functions.c

@@ -679,6 +679,7 @@ win32_WaitForMultipleObjects(PyObject* self, PyObject* args)
    DWORD result;
    PyObject *handle_seq;
    HANDLE handles[MAXIMUM_WAIT_OBJECTS];
    HANDLE sigint_event = NULL;
    Py_ssize_t nhandles, i;
    int wait_flag;
    int milliseconds = INFINITE;
@@ -696,10 +697,10 @@ win32_WaitForMultipleObjects(PyObject* self, PyObject* args)
    nhandles = PySequence_Length(handle_seq);
    if (nhandles == -1)
        return NULL;
    if (nhandles < 0 || nhandles >= MAXIMUM_WAIT_OBJECTS) {
    if (nhandles < 0 || nhandles >= MAXIMUM_WAIT_OBJECTS - 1) {
        PyErr_Format(PyExc_ValueError,
                     "need at most %zd handles, got a sequence of length %zd",
                     MAXIMUM_WAIT_OBJECTS, nhandles);
                     MAXIMUM_WAIT_OBJECTS - 1, nhandles);
        return NULL;
    }
    for (i = 0; i < nhandles; i++) {
@@ -711,14 +712,27 @@ win32_WaitForMultipleObjects(PyObject* self, PyObject* args)
            return NULL;
        handles[i] = h;
    }
    /* If this is the main thread then make the wait interruptible
       by Ctrl-C unless we are waiting for *all* handles */
    if (!wait_flag && _PyOS_IsMainThread()) {
        sigint_event = _PyOS_SigintEvent();
        assert(sigint_event != NULL);
        handles[nhandles++] = sigint_event;
    }

    Py_BEGIN_ALLOW_THREADS
    if (sigint_event != NULL)
        ResetEvent(sigint_event);
    result = WaitForMultipleObjects((DWORD) nhandles, handles,
                                    (BOOL) wait_flag, (DWORD) milliseconds);
    Py_END_ALLOW_THREADS

    if (result == WAIT_FAILED)
        return PyErr_SetExcFromWindowsErr(PyExc_IOError, 0);
    else if (sigint_event != NULL && result == WAIT_OBJECT_0 + nhandles - 1) {
        errno = EINTR;
        return PyErr_SetFromErrno(PyExc_IOError);
    }

    return PyLong_FromLong((int) result);
}

Modules/signalmodule.c

@@ -109,6 +109,10 @@ static PyObject *IntHandler;

static PyOS_sighandler_t old_siginthandler = SIG_DFL;

#ifdef MS_WINDOWS
static HANDLE sigint_event = NULL;
#endif

#ifdef HAVE_GETITIMER
static PyObject *ItimerError;

@@ -229,6 +233,11 @@ signal_handler(int sig_num)
    /* Issue #10311: asynchronously executing signal handlers should not
       mutate errno under the feet of unsuspecting C code. */
    errno = save_errno;

#ifdef MS_WINDOWS
    if (sig_num == SIGINT)
        SetEvent(sigint_event);
#endif
}


@@ -1253,6 +1262,11 @@ PyInit_signal(void)
    Py_DECREF(x);
#endif

#ifdef MS_WINDOWS
    /* Create manual-reset event, initially unset */
    sigint_event = CreateEvent(NULL, TRUE, FALSE, FALSE);
#endif

    if (PyErr_Occurred()) {
        Py_DECREF(m);
        m = NULL;
@@ -1397,3 +1411,25 @@ PyOS_AfterFork(void)
    PyThread_ReInitTLS();
#endif
}

int
_PyOS_IsMainThread(void)
{
#ifdef WITH_THREAD
    return PyThread_get_thread_ident() == main_thread;
#else
    return 1;
#endif
}

#ifdef MS_WINDOWS
void *_PyOS_SigintEvent(void)
{
    /* Returns a manual-reset event which gets tripped whenever
       SIGINT is received.

       Python.h does not include windows.h so we do cannot use HANDLE
       as the return type of this function.  We use void* instead. */
    return sigint_event;
}
#endif

Modules/timemodule.c

@@ -21,19 +21,6 @@
#include <windows.h>
#include "pythread.h"

/* helper to allow us to interrupt sleep() on Windows*/
static HANDLE hInterruptEvent = NULL;
static BOOL WINAPI PyCtrlHandler(DWORD dwCtrlType)
{
    SetEvent(hInterruptEvent);
    /* allow other default handlers to be called.
       Default Python handler will setup the
       KeyboardInterrupt exception.
    */
    return FALSE;
}
static long main_thread;

#if defined(__BORLANDC__)
/* These overrides not needed for Win32 */
#define timezone _timezone
@@ -955,15 +942,6 @@ PyInit_time(void)
    /* Set, or reset, module variables like time.timezone */
    PyInit_timezone(m);

#ifdef MS_WINDOWS
    /* Helper to allow interrupts for Windows.
       If Ctrl+C event delivered while not sleeping
       it will be ignored.
    */
    main_thread = PyThread_get_thread_ident();
    hInterruptEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
    SetConsoleCtrlHandler( PyCtrlHandler, TRUE);
#endif /* MS_WINDOWS */
    if (!initialized) {
        PyStructSequence_InitType(&StructTimeType,
                                  &struct_time_type_desc);
@@ -1036,18 +1014,14 @@ floatsleep(double secs)
         * by Guido, only the main thread can be interrupted.
         */
        ul_millis = (unsigned long)millisecs;
        if (ul_millis == 0 ||
            main_thread != PyThread_get_thread_ident())
        if (ul_millis == 0 || !_PyOS_IsMainThread())
            Sleep(ul_millis);
        else {
            DWORD rc;
            HANDLE hInterruptEvent = _PyOS_SigintEvent();
            ResetEvent(hInterruptEvent);
            rc = WaitForSingleObject(hInterruptEvent, ul_millis);
            if (rc == WAIT_OBJECT_0) {
                /* Yield to make sure real Python signal
                 * handler called.
                 */
                Sleep(1);
                Py_BLOCK_THREADS
                errno = EINTR;
                PyErr_SetFromErrno(PyExc_IOError);