Python thread start （C source code)

static PyMethodDef thread_methods[] = {
    {"start_new_thread",        (PyCFunction)thread_PyThread_start_new_thread,
                            METH_VARARGS,
                            start_new_doc},
    {"start_new",               (PyCFunction)thread_PyThread_start_new_thread,
                            METH_VARARGS,
                            start_new_doc},
    {"allocate_lock",           (PyCFunction)thread_PyThread_allocate_lock,
     METH_NOARGS, allocate_doc},
    {"allocate",                (PyCFunction)thread_PyThread_allocate_lock,
     METH_NOARGS, allocate_doc},
    {"exit_thread",             (PyCFunction)thread_PyThread_exit_thread,
     METH_NOARGS, exit_doc},
    {"exit",                    (PyCFunction)thread_PyThread_exit_thread,
     METH_NOARGS, exit_doc},
    {"interrupt_main",          (PyCFunction)thread_PyThread_interrupt_main,
     METH_NOARGS, interrupt_doc},
    {"get_ident",               (PyCFunction)thread_get_ident,
     METH_NOARGS, get_ident_doc},
    {"_count",                  (PyCFunction)thread__count,
     METH_NOARGS, _count_doc},
    {"stack_size",              (PyCFunction)thread_stack_size,
                            METH_VARARGS,
                            stack_size_doc},
    {NULL,                      NULL}           /* sentinel */
};

/*创建bootstate，并初始化，其保存关于线程的一切信息，如线程过程，和参数等，*/
static PyObject *
thread_PyThread_start_new_thread(PyObject *self, PyObject *fargs)
{
    PyObject *func, *args, *keyw = NULL;
    struct bootstate *boot;
    long ident;

    if (!PyArg_UnpackTuple(fargs, "start_new_thread", 2, 3,
                           &func, &args, &keyw))
        return NULL;
    if (!PyCallable_Check(func)) {
        PyErr_SetString(PyExc_TypeError,
                        "first arg must be callable");
        return NULL;
    }
    if (!PyTuple_Check(args)) {
        PyErr_SetString(PyExc_TypeError,
                        "2nd arg must be a tuple");
        return NULL;
    }
    if (keyw != NULL && !PyDict_Check(keyw)) {
        PyErr_SetString(PyExc_TypeError,
                        "optional 3rd arg must be a dictionary");
        return NULL;
    }
    boot = PyMem_NEW(struct bootstate, 1);
    if (boot == NULL)
        return PyErr_NoMemory();
    boot->interp = PyThreadState_GET()->interp;
    boot->func = func;
    boot->args = args;
    boot->keyw = keyw;
    boot->tstate = _PyThreadState_Prealloc(boot->interp);
    if (boot->tstate == NULL) {
        PyMem_DEL(boot);
        return PyErr_NoMemory();
    }
    Py_INCREF(func);
    Py_INCREF(args);
    Py_XINCREF(keyw);
    PyEval_InitThreads(); /* Start the interpreter‘s thread-awareness */
    ident = PyThread_start_new_thread(t_bootstrap, (void*) boot);
    if (ident == -1) {
        PyErr_SetString(ThreadError, "can‘t start new thread");
        Py_DECREF(func);
        Py_DECREF(args);
        Py_XDECREF(keyw);
        PyThreadState_Clear(boot->tstate);
        PyMem_DEL(boot);
        return NULL;
    }
    return PyInt_FromLong(ident);
}



/*以boot为参数，创建一个原生线程*/
PyThreadState *
_PyThreadState_Prealloc(PyInterpreterState *interp)
{
    return new_threadstate(interp, 0);
}

static PyThreadState *
new_threadstate(PyInterpreterState *interp, int init)
{
    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;

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

        if (init)
            _PyThreadState_Init(tstate);

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

    return tstate;
}

 1 /*
 2  * Lock support. It has too be implemented as semaphores.
 3  * I [Dag] tried to implement it with mutex but I could find a way to
 4  * tell whether a thread already own the lock or not.
 5  */
 6 PyThread_type_lock
 7 PyThread_allocate_lock(void)
 8 {
 9     PNRMUTEX aLock;
10 
11     dprintf(("PyThread_allocate_lock called\n"));
12     if (!initialized)
13         PyThread_init_thread();
14 
15     aLock = AllocNonRecursiveMutex() ;
16 
17     dprintf(("%ld: PyThread_allocate_lock() -> %p\n", PyThread_get_thread_ident(), aLock));
18 
19     return (PyThread_type_lock) aLock;
20 }
21 
22 typedef struct NRMUTEX {
23     LONG   owned ;
24     DWORD  thread_id ;
25     HANDLE hevent ;
26 } NRMUTEX, *PNRMUTEX ;
27 
28 PNRMUTEX
29 AllocNonRecursiveMutex(void)
30 {
31     PNRMUTEX mutex = (PNRMUTEX)malloc(sizeof(NRMUTEX)) ;
32     if (mutex && !InitializeNonRecursiveMutex(mutex))
33     {
34         free(mutex) ;
35         mutex = NULL ;
36     }
37     return mutex ;
38 }
39 
40 BOOL
41 InitializeNonRecursiveMutex(PNRMUTEX mutex)
42 {
43     mutex->owned = -1 ;  /* No threads have entered NonRecursiveMutex */
44     mutex->thread_id = 0 ;
45     mutex->hevent = CreateEvent(NULL, FALSE, FALSE, NULL) ;
46     return mutex->hevent != NULL ;      /* TRUE if the mutex is created */
47 }

void
PyEval_InitThreads(void)
{
    if (interpreter_lock)
        return;
    interpreter_lock = PyThread_allocate_lock();
    PyThread_acquire_lock(interpreter_lock, 1);
    main_thread = PyThread_get_thread_ident();
}

/*
 * Return 1 on success if the lock was acquired
 *
 * 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(PyThread_type_lock aLock, int waitflag)
{
    int success ;

    dprintf(("%ld: PyThread_acquire_lock(%p, %d) called\n", PyThread_get_thread_ident(),aLock, waitflag));

    success = aLock && EnterNonRecursiveMutex((PNRMUTEX) aLock, (waitflag ? INFINITE : 0)) == WAIT_OBJECT_0 ;

    dprintf(("%ld: PyThread_acquire_lock(%p, %d) -> %d\n", PyThread_get_thread_ident(),aLock, waitflag, success));

    return success;
}

DWORD
EnterNonRecursiveMutex(PNRMUTEX mutex, BOOL wait)
{
    /* Assume that the thread waits successfully */
    DWORD ret ;

    /* InterlockedIncrement(&mutex->owned) == 0 means that no thread currently owns the mutex */
    if (!wait)
    {
        if (InterlockedCompareExchange(&mutex->owned, 0, -1) != -1)
            return WAIT_TIMEOUT ;
        ret = WAIT_OBJECT_0 ;
    }
    else
        ret = InterlockedIncrement(&mutex->owned) ?
            /* Some thread owns the mutex, let‘s wait... */
            WaitForSingleObject(mutex->hevent, INFINITE) : WAIT_OBJECT_0 ;

    mutex->thread_id = GetCurrentThreadId() ; /* We own it */
    return ret ;
}