C++ HEAD_LOCK函数代码示例

void
PyInterpreterState_Delete(PyInterpreterState *interp)
{
    PyInterpreterState **p;
    zapthreads(interp);
    HEAD_LOCK();
    for (p = &_PyRuntime.interpreters.head; ; p = &(*p)->next) {
        if (*p == NULL)
            Py_FatalError(
                "PyInterpreterState_Delete: invalid interp");
        if (*p == interp)
            break;
    }
    if (interp->tstate_head != NULL)
        Py_FatalError("PyInterpreterState_Delete: remaining threads");
    *p = interp->next;
    if (_PyRuntime.interpreters.main == interp) {
        _PyRuntime.interpreters.main = NULL;
        if (_PyRuntime.interpreters.head != NULL)
            Py_FatalError("PyInterpreterState_Delete: remaining subinterpreters");
    }
    HEAD_UNLOCK();
    if (interp->id_mutex != NULL) {
        PyThread_free_lock(interp->id_mutex);
    }
    if (interp->ceval.pending.lock != NULL) {
        PyThread_free_lock(interp->ceval.pending.lock);
    }
    PyMem_RawFree(interp);
}

/*
 * Delete all interpreter states except the main interpreter.  If there
 * is a current interpreter state, it *must* be the main interpreter.
 */
void
_PyInterpreterState_DeleteExceptMain()
{
    PyThreadState *tstate = PyThreadState_Swap(NULL);
    if (tstate != NULL && tstate->interp != _PyRuntime.interpreters.main) {
        Py_FatalError("PyInterpreterState_DeleteExceptMain: not main interpreter");
    }

    HEAD_LOCK();
    PyInterpreterState *interp = _PyRuntime.interpreters.head;
    _PyRuntime.interpreters.head = NULL;
    while (interp != NULL) {
        if (interp == _PyRuntime.interpreters.main) {
            _PyRuntime.interpreters.main->next = NULL;
            _PyRuntime.interpreters.head = interp;
            interp = interp->next;
            continue;
        }

        PyInterpreterState_Clear(interp);  // XXX must activate?
        zapthreads(interp);
        if (interp->id_mutex != NULL) {
            PyThread_free_lock(interp->id_mutex);
        }
        PyInterpreterState *prev_interp = interp;
        interp = interp->next;
        PyMem_RawFree(prev_interp);
    }
    HEAD_UNLOCK();

    if (_PyRuntime.interpreters.head == NULL) {
        Py_FatalError("PyInterpreterState_DeleteExceptMain: missing main");
    }
    PyThreadState_Swap(tstate);
}

/*
 * Delete all thread states except the one passed as argument.
 * Note that, if there is a current thread state, it *must* be the one
 * passed as argument.  Also, this won't touch any other interpreters
 * than the current one, since we don't know which thread state should
 * be kept in those other interpreteres.
 */
void
_PyThreadState_DeleteExcept(PyThreadState *tstate)
{
    PyInterpreterState *interp = tstate->interp;
    PyThreadState *p, *next, *garbage;
    HEAD_LOCK();
    /* Remove all thread states, except tstate, from the linked list of
       thread states.  This will allow calling PyThreadState_Clear()
       without holding the lock. */
    garbage = interp->tstate_head;
    if (garbage == tstate)
        garbage = tstate->next;
    if (tstate->prev)
        tstate->prev->next = tstate->next;
    if (tstate->next)
        tstate->next->prev = tstate->prev;
    tstate->prev = tstate->next = NULL;
    interp->tstate_head = tstate;
    HEAD_UNLOCK();
    /* Clear and deallocate all stale thread states.  Even if this
       executes Python code, we should be safe since it executes
       in the current thread, not one of the stale threads. */
    for (p = garbage; p; p = next) {
        next = p->next;
        PyThreadState_Clear(p);
        PyMem_RawFree(p);
    }
}

void
PyInterpreterState_Clear(PyInterpreterState *interp)
{
    PyThreadState *p;
    HEAD_LOCK();
    for (p = interp->tstate_head; p != NULL; p = p->next)
        PyThreadState_Clear(p);
    HEAD_UNLOCK();
    _PyCoreConfig_Clear(&interp->core_config);
    _PyMainInterpreterConfig_Clear(&interp->config);
    Py_CLEAR(interp->codec_search_path);
    Py_CLEAR(interp->codec_search_cache);
    Py_CLEAR(interp->codec_error_registry);
    Py_CLEAR(interp->modules);
    Py_CLEAR(interp->modules_by_index);
    Py_CLEAR(interp->sysdict);
    Py_CLEAR(interp->builtins);
    Py_CLEAR(interp->builtins_copy);
    Py_CLEAR(interp->importlib);
    Py_CLEAR(interp->import_func);
#ifdef HAVE_FORK
    Py_CLEAR(interp->before_forkers);
    Py_CLEAR(interp->after_forkers_parent);
    Py_CLEAR(interp->after_forkers_child);
#endif
    // XXX Once we have one allocator per interpreter (i.e.
    // per-interpreter GC) we must ensure that all of the interpreter's
    // objects have been cleaned up at the point.
}

int
PyThreadState_SetAsyncExc(long id, PyObject *exc) {
    PyThreadState *tstate = PyThreadState_GET();
    PyInterpreterState *interp = tstate->interp;
    PyThreadState *p;

    /* Although the GIL is held, a few C API functions can be called
     * without the GIL held, and in particular some that create and
     * destroy thread and interpreter states.  Those can mutate the
     * list of thread states we're traversing, so to prevent that we lock
     * head_mutex for the duration.
     */
    HEAD_LOCK();
    for (p = interp->tstate_head; p != NULL; p = p->next) {
        if (p->thread_id == id) {
            /* Tricky:  we need to decref the current value
             * (if any) in p->async_exc, but that can in turn
             * allow arbitrary Python code to run, including
             * perhaps calls to this function.  To prevent
             * deadlock, we need to release head_mutex before
             * the decref.
             */
            PyObject *old_exc = p->async_exc;
            Py_XINCREF(exc);
            p->async_exc = exc;
            HEAD_UNLOCK();
            Py_XDECREF(old_exc);
            return 1;
        }
    }
    HEAD_UNLOCK();
    return 0;
}

void
PyInterpreterState_Delete(PyInterpreterState *interp)
{
    PyInterpreterState **p;
    zapthreads(interp);
    HEAD_LOCK();
    for (p = &interp_head; ; p = &(*p)->next) {
        if (*p == NULL)
            Py_FatalError(
                "PyInterpreterState_Delete: invalid interp");
        if (*p == interp)
            break;
    }
    if (interp->tstate_head != NULL)
        Py_FatalError("PyInterpreterState_Delete: remaining threads");
    *p = interp->next;
    HEAD_UNLOCK();
    PyMem_RawFree(interp);
#ifdef WITH_THREAD
    if (interp_head == NULL && head_mutex != NULL) {
        PyThread_free_lock(head_mutex);
        head_mutex = NULL;
    }
#endif
}

static PyThreadState *
new_threadstate(PyInterpreterState *interp, int init)
{
    PyThreadState *tstate = (PyThreadState *)PyMem_RawMalloc(sizeof(PyThreadState));

    if (_PyThreadState_GetFrame == NULL)
        _PyThreadState_GetFrame = threadstate_getframe;

    if (tstate != NULL) {
        tstate->interp = interp;

        tstate->frame = NULL;
        tstate->recursion_depth = 0;
        tstate->overflowed = 0;
        tstate->recursion_critical = 0;
        tstate->tracing = 0;
        tstate->use_tracing = 0;
        tstate->tick_counter = 0;
        tstate->gilstate_counter = 0;
        tstate->async_exc = NULL;
#ifdef WITH_THREAD
        tstate->thread_id = PyThread_get_thread_ident();
#else
        tstate->thread_id = 0;
#endif

        tstate->dict = NULL;

        tstate->curexc_type = NULL;
        tstate->curexc_value = NULL;
        tstate->curexc_traceback = NULL;

        tstate->exc_type = NULL;
        tstate->exc_value = NULL;
        tstate->exc_traceback = NULL;

        tstate->c_profilefunc = NULL;
        tstate->c_tracefunc = NULL;
        tstate->c_profileobj = NULL;
        tstate->c_traceobj = NULL;

        tstate->trash_delete_nesting = 0;
        tstate->trash_delete_later = NULL;
        tstate->on_delete = NULL;
        tstate->on_delete_data = NULL;

        if (init)
            _PyThreadState_Init(tstate);

        HEAD_LOCK();
        tstate->prev = NULL;
        tstate->next = interp->tstate_head;
        if (tstate->next)
            tstate->next->prev = tstate;
        interp->tstate_head = tstate;
        HEAD_UNLOCK();
    }

    return tstate;
}

PyInterpreterState *
PyInterpreterState_New(void)
{
    PyInterpreterState *interp = (PyInterpreterState *)
                                 PyMem_RawMalloc(sizeof(PyInterpreterState));

    if (interp != NULL) {
        HEAD_INIT();
#ifdef WITH_THREAD
        if (head_mutex == NULL)
            Py_FatalError("Can't initialize threads for interpreter");
#endif
        interp->modules = NULL;
        interp->modules_by_index = NULL;
        interp->sysdict = NULL;
        interp->builtins = NULL;
        interp->builtins_copy = NULL;
        interp->tstate_head = NULL;
        interp->codec_search_path = NULL;
        interp->codec_search_cache = NULL;
        interp->codec_error_registry = NULL;
        interp->codecs_initialized = 0;
        interp->fscodec_initialized = 0;
        interp->importlib = NULL;
        interp->import_func = NULL;
        interp->eval_frame = _PyEval_EvalFrameDefault;
#ifdef HAVE_DLOPEN
#if HAVE_DECL_RTLD_NOW
        interp->dlopenflags = RTLD_NOW;
#else
        interp->dlopenflags = RTLD_LAZY;
#endif
#endif
#ifdef HAVE_FORK
        interp->before_forkers = NULL;
        interp->after_forkers_parent = NULL;
        interp->after_forkers_child = NULL;
#endif

        HEAD_LOCK();
        interp->next = interp_head;
        if (interp_main == NULL) {
            interp_main = interp;
        }
        interp_head = interp;
        if (_next_interp_id < 0) {
            /* overflow or Py_Initialize() not called! */
            PyErr_SetString(PyExc_RuntimeError,
                            "failed to get an interpreter ID");
            interp = NULL;
        } else {
            interp->id = _next_interp_id;
            _next_interp_id += 1;
        }
        HEAD_UNLOCK();
    }

    return interp;
}

PyThreadState *
PyThreadState_New(PyInterpreterState *interp)
{
	PyThreadState *tstate = (PyThreadState *)malloc(sizeof(PyThreadState));

	if (_PyThreadState_GetFrame == NULL)
		_PyThreadState_GetFrame = threadstate_getframe;

	if (tstate != NULL) {
		tstate->interp = interp;

		tstate->frame = NULL;
		tstate->recursion_depth = 0;
		tstate->tracing = 0;
		tstate->use_tracing = 0;
		tstate->tick_counter = 0;
		tstate->gilstate_counter = 0;
		tstate->async_exc = NULL;
#ifdef WITH_THREAD
		tstate->thread_id = PyThread_get_thread_ident();
#else
		tstate->thread_id = 0;
#endif

		tstate->dict = NULL;

		tstate->curexc_type = NULL;
		tstate->curexc_value = NULL;
		tstate->curexc_traceback = NULL;

		tstate->exc_type = NULL;
		tstate->exc_value = NULL;
		tstate->exc_traceback = NULL;

		tstate->c_profilefunc = NULL;
		tstate->c_tracefunc = NULL;
		tstate->c_profileobj = NULL;
		tstate->c_traceobj = NULL;
#ifdef STACKLESS
		STACKLESS_PYSTATE_NEW;
#endif

#ifdef WITH_THREAD
		_PyGILState_NoteThreadState(tstate);
#endif

		HEAD_LOCK();
		tstate->next = interp->tstate_head;
		interp->tstate_head = tstate;
		HEAD_UNLOCK();
	}

	return tstate;
}

void
PyInterpreterState_Clear(PyInterpreterState *interp)
{
    PyThreadState *p;
    HEAD_LOCK();
    for (p = interp->tstate_head; p != NULL; p = p->next)
        PyThreadState_Clear(p);
    HEAD_UNLOCK();
    Py_CLEAR(interp->codec_search_path);
    Py_CLEAR(interp->codec_search_cache);
    Py_CLEAR(interp->codec_error_registry);
    Py_CLEAR(interp->modules);
    Py_CLEAR(interp->modules_reloading);
    Py_CLEAR(interp->sysdict);
    Py_CLEAR(interp->builtins);
}

PyInterpreterState *
PyInterpreterState_New(void)
{
    PyInterpreterState *interp = (PyInterpreterState *)
                                 PyMem_RawMalloc(sizeof(PyInterpreterState));

    if (interp != NULL) {
        HEAD_INIT();
#ifdef WITH_THREAD
        if (head_mutex == NULL)
            Py_FatalError("Can't initialize threads for interpreter");
#endif
        interp->modules = NULL;
        interp->modules_by_index = NULL;
        interp->sysdict = NULL;
        interp->builtins = NULL;
        interp->builtins_copy = NULL;
        interp->tstate_head = NULL;
        interp->codec_search_path = NULL;
        interp->codec_search_cache = NULL;
        interp->codec_error_registry = NULL;
        interp->codecs_initialized = 0;
        interp->fscodec_initialized = 0;
        interp->importlib = NULL;
#ifdef HAVE_DLOPEN
#ifdef RTLD_NOW
        interp->dlopenflags = RTLD_NOW;
#else
        interp->dlopenflags = RTLD_LAZY;
#endif
#endif
#ifdef WITH_TSC
        interp->tscdump = 0;
#endif

        HEAD_LOCK();
        interp->next = interp_head;
        interp_head = interp;
        HEAD_UNLOCK();
    }

    return interp;
}

void
PyInterpreterState_Delete(PyInterpreterState *interp)
{
    PyInterpreterState **p;
    zapthreads(interp);
    HEAD_LOCK();
    for (p = &interp_head; ; p = &(*p)->next) {
        if (*p == NULL)
            Py_FatalError(
                "PyInterpreterState_Delete: invalid interp");
        if (*p == interp)
            break;
    }
    if (interp->tstate_head != NULL)
        Py_FatalError("PyInterpreterState_Delete: remaining threads");
    *p = interp->next;
    HEAD_UNLOCK();
    free(interp);
}

/* The implementation of sys._current_frames().  This is intended to be
   called with the GIL held, as it will be when called via
   sys._current_frames().  It's possible it would work fine even without
   the GIL held, but haven't thought enough about that.
*/
PyObject *
_PyThread_CurrentFrames(void)
{
    PyObject *result;
    PyInterpreterState *i;

    result = PyDict_New();
    if (result == NULL)
        return NULL;

    /* for i in all interpreters:
     *     for t in all of i's thread states:
     *          if t's frame isn't NULL, map t's id to its frame
     * Because these lists can mutate even when the GIL is held, we
     * need to grab head_mutex for the duration.
     */
    HEAD_LOCK();
    for (i = interp_head; i != NULL; i = i->next) {
        PyThreadState *t;
        for (t = i->tstate_head; t != NULL; t = t->next) {
            PyObject *id;
            int stat;
            struct _frame *frame = t->frame;
            if (frame == NULL)
                continue;
            id = PyInt_FromLong(t->thread_id);
            if (id == NULL)
                goto Fail;
            stat = PyDict_SetItem(result, id, (PyObject *)frame);
            Py_DECREF(id);
            if (stat < 0)
                goto Fail;
        }
    }
    HEAD_UNLOCK();
    return result;

 Fail:
    HEAD_UNLOCK();
    Py_DECREF(result);
    return NULL;
}

/* Common code for PyThreadState_Delete() and PyThreadState_DeleteCurrent() */
static void
tstate_delete_common(PyThreadState *tstate)
{
    PyInterpreterState *interp;
    if (tstate == NULL)
        Py_FatalError("PyThreadState_Delete: NULL tstate");
    interp = tstate->interp;
    if (interp == NULL)
        Py_FatalError("PyThreadState_Delete: NULL interp");
    HEAD_LOCK();
    if (tstate->prev)
        tstate->prev->next = tstate->next;
    else
        interp->tstate_head = tstate->next;
    if (tstate->next)
        tstate->next->prev = tstate->prev;
    HEAD_UNLOCK();
    if (tstate->on_delete != NULL) {
        tstate->on_delete(tstate->on_delete_data);
    }
    PyMem_RawFree(tstate);
}

/* Common code for PyThreadState_Delete() and PyThreadState_DeleteCurrent() */
static void
tstate_delete_common(PyThreadState *tstate)
{
	PyInterpreterState *interp;
	PyThreadState **p;
	if (tstate == NULL)
		Py_FatalError("PyThreadState_Delete: NULL tstate");
	interp = tstate->interp;
	if (interp == NULL)
		Py_FatalError("PyThreadState_Delete: NULL interp");
	HEAD_LOCK();
	for (p = &interp->tstate_head; ; p = &(*p)->next) {
		if (*p == NULL)
			Py_FatalError(
				"PyThreadState_Delete: invalid tstate");
		if (*p == tstate)
			break;
	}
	*p = tstate->next;
	HEAD_UNLOCK();
	free(tstate);
}