cpython/Modules/_threadmodule.c at master · python-emscripten/cpython · GitHub

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/* Thread module */

/* Interface to Sjoerd's portable C thread library */

#include "Python.h"

#include "pycore_pylifecycle.h"

#include "pycore_interp.h" // _PyInterpreterState.num_threads

#include "pycore_pystate.h" // _PyThreadState_Init()

#include <stddef.h> // offsetof()

static PyObject *ThreadError;

static PyObject *str_dict;

_Py_IDENTIFIER(stderr);

_Py_IDENTIFIER(flush);

/* Lock objects */

typedef struct {

PyObject_HEAD

PyThread_type_lock lock_lock;

PyObject *in_weakreflist;

char locked; /* for sanity checking */

} lockobject;

static void

lock_dealloc(lockobject *self)

{

if (self->in_weakreflist != NULL)

PyObject_ClearWeakRefs((PyObject *) self);

if (self->lock_lock != NULL) {

/* Unlock the lock so it's safe to free it */

if (self->locked)

PyThread_release_lock(self->lock_lock);

PyThread_free_lock(self->lock_lock);

}

PyObject_Del(self);

}

/* Helper to acquire an interruptible lock with a timeout. If the lock acquire

* is interrupted, signal handlers are run, and if they raise an exception,

* PY_LOCK_INTR is returned. Otherwise, PY_LOCK_ACQUIRED or PY_LOCK_FAILURE

* are returned, depending on whether the lock can be acquired within the

* timeout.

static PyLockStatus

acquire_timed(PyThread_type_lock lock, _PyTime_t timeout)

{

PyLockStatus r;

_PyTime_t endtime = 0;

_PyTime_t microseconds;

if (timeout > 0)

endtime = _PyTime_GetMonotonicClock() + timeout;

do {

microseconds = _PyTime_AsMicroseconds(timeout, _PyTime_ROUND_CEILING);

/* first a simple non-blocking try without releasing the GIL */

r = PyThread_acquire_lock_timed(lock, 0, 0);

if (r == PY_LOCK_FAILURE && microseconds != 0) {

Py_BEGIN_ALLOW_THREADS

r = PyThread_acquire_lock_timed(lock, microseconds, 1);

Py_END_ALLOW_THREADS

}

if (r == PY_LOCK_INTR) {

/* Run signal handlers if we were interrupted. Propagate

* exceptions from signal handlers, such as KeyboardInterrupt, by

* passing up PY_LOCK_INTR. */

if (Py_MakePendingCalls() < 0) {

return PY_LOCK_INTR;

}

/* If we're using a timeout, recompute the timeout after processing

* signals, since those can take time. */

if (timeout > 0) {

timeout = endtime - _PyTime_GetMonotonicClock();

/* Check for negative values, since those mean block forever.

if (timeout < 0) {

r = PY_LOCK_FAILURE;

}

} while (r == PY_LOCK_INTR); /* Retry if we were interrupted. */

return r;

}

static int

lock_acquire_parse_args(PyObject *args, PyObject *kwds,

_PyTime_t *timeout)

{

char *kwlist[] = {"blocking", "timeout", NULL};

int blocking = 1;

PyObject *timeout_obj = NULL;

const _PyTime_t unset_timeout = _PyTime_FromSeconds(-1);

*timeout = unset_timeout ;

if (!PyArg_ParseTupleAndKeywords(args, kwds, "|iO:acquire", kwlist,

&blocking, &timeout_obj))

return -1;

if (timeout_obj

&& _PyTime_FromSecondsObject(timeout,

timeout_obj, _PyTime_ROUND_TIMEOUT) < 0)

return -1;

if (!blocking && *timeout != unset_timeout ) {

PyErr_SetString(PyExc_ValueError,

"can't specify a timeout for a non-blocking call");

return -1;

}

if (*timeout < 0 && *timeout != unset_timeout) {

PyErr_SetString(PyExc_ValueError,

"timeout value must be positive");

return -1;

}

if (!blocking)

*timeout = 0;

else if (*timeout != unset_timeout) {

_PyTime_t microseconds;

microseconds = _PyTime_AsMicroseconds(*timeout, _PyTime_ROUND_TIMEOUT);

if (microseconds >= PY_TIMEOUT_MAX) {

PyErr_SetString(PyExc_OverflowError,

"timeout value is too large");

return -1;

}

return 0;

}

static PyObject *

lock_PyThread_acquire_lock(lockobject *self, PyObject *args, PyObject *kwds)

{

_PyTime_t timeout;

PyLockStatus r;

if (lock_acquire_parse_args(args, kwds, &timeout) < 0)

return NULL;

r = acquire_timed(self->lock_lock, timeout);

if (r == PY_LOCK_INTR) {

return NULL;

}

if (r == PY_LOCK_ACQUIRED)

self->locked = 1;

return PyBool_FromLong(r == PY_LOCK_ACQUIRED);

}

PyDoc_STRVAR(acquire_doc,

"acquire(blocking=True, timeout=-1) -> bool\n\

(acquire_lock() is an obsolete synonym)\n\

\n\

Lock the lock. Without argument, this blocks if the lock is already\n\

locked (even by the same thread), waiting for another thread to release\n\

the lock, and return True once the lock is acquired.\n\

With an argument, this will only block if the argument is true,\n\

and the return value reflects whether the lock is acquired.\n\

The blocking operation is interruptible.");

static PyObject *

lock_PyThread_release_lock(lockobject *self, PyObject *Py_UNUSED(ignored))

{

/* Sanity check: the lock must be locked */

if (!self->locked) {

PyErr_SetString(ThreadError, "release unlocked lock");

return NULL;

}

PyThread_release_lock(self->lock_lock);

self->locked = 0;

Py_RETURN_NONE;

}

PyDoc_STRVAR(release_doc,

"release()\n\

(release_lock() is an obsolete synonym)\n\

\n\

Release the lock, allowing another thread that is blocked waiting for\n\

the lock to acquire the lock. The lock must be in the locked state,\n\

but it needn't be locked by the same thread that unlocks it.");

static PyObject *

lock_locked_lock(lockobject *self, PyObject *Py_UNUSED(ignored))

{

return PyBool_FromLong((long)self->locked);

}

PyDoc_STRVAR(locked_doc,

"locked() -> bool\n\

(locked_lock() is an obsolete synonym)\n\

\n\

Return whether the lock is in the locked state.");

static PyObject *

lock_repr(lockobject *self)

{

return PyUnicode_FromFormat("<%s %s object at %p>",

self->locked ? "locked" : "unlocked", Py_TYPE(self)->tp_name, self);

}

#ifdef HAVE_FORK

static PyObject *

lock__at_fork_reinit(lockobject *self, PyObject *Py_UNUSED(args))

{

if (_PyThread_at_fork_reinit(&self->lock_lock) < 0) {

PyErr_SetString(ThreadError, "failed to reinitialize lock at fork");

return NULL;

}

self->locked = 0;

Py_RETURN_NONE;

}

#endif /* HAVE_FORK */

static PyMethodDef lock_methods[] = {

{"acquire_lock", (PyCFunction)(void(*)(void))lock_PyThread_acquire_lock,

METH_VARARGS | METH_KEYWORDS, acquire_doc},

{"acquire", (PyCFunction)(void(*)(void))lock_PyThread_acquire_lock,

METH_VARARGS | METH_KEYWORDS, acquire_doc},

{"release_lock", (PyCFunction)lock_PyThread_release_lock,

METH_NOARGS, release_doc},

{"release", (PyCFunction)lock_PyThread_release_lock,

METH_NOARGS, release_doc},

{"locked_lock", (PyCFunction)lock_locked_lock,

METH_NOARGS, locked_doc},

{"locked", (PyCFunction)lock_locked_lock,

METH_NOARGS, locked_doc},

{"__enter__", (PyCFunction)(void(*)(void))lock_PyThread_acquire_lock,

METH_VARARGS | METH_KEYWORDS, acquire_doc},

{"__exit__", (PyCFunction)lock_PyThread_release_lock,

METH_VARARGS, release_doc},

#ifdef HAVE_FORK

{"_at_fork_reinit", (PyCFunction)lock__at_fork_reinit,

METH_NOARGS, NULL},

#endif

{NULL, NULL} /* sentinel */

};

static PyTypeObject Locktype = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

"_thread.lock", /*tp_name*/

sizeof(lockobject), /*tp_basicsize*/

0, /*tp_itemsize*/

/* methods */

(destructor)lock_dealloc, /*tp_dealloc*/

0, /*tp_vectorcall_offset*/

0, /*tp_getattr*/

0, /*tp_setattr*/

0, /*tp_as_async*/

(reprfunc)lock_repr, /*tp_repr*/

0, /*tp_as_number*/

0, /*tp_as_sequence*/

0, /*tp_as_mapping*/

0, /*tp_hash*/

0, /*tp_call*/

0, /*tp_str*/

0, /*tp_getattro*/

0, /*tp_setattro*/

0, /*tp_as_buffer*/

Py_TPFLAGS_DEFAULT, /*tp_flags*/

0, /*tp_doc*/

0, /*tp_traverse*/

0, /*tp_clear*/

0, /*tp_richcompare*/

offsetof(lockobject, in_weakreflist), /*tp_weaklistoffset*/

0, /*tp_iter*/

0, /*tp_iternext*/

lock_methods, /*tp_methods*/

};

/* Recursive lock objects */

typedef struct {

PyObject_HEAD

PyThread_type_lock rlock_lock;

unsigned long rlock_owner;

unsigned long rlock_count;

PyObject *in_weakreflist;

} rlockobject;

static void

rlock_dealloc(rlockobject *self)

{

if (self->in_weakreflist != NULL)

PyObject_ClearWeakRefs((PyObject *) self);

/* self->rlock_lock can be NULL if PyThread_allocate_lock() failed

in rlock_new() */

if (self->rlock_lock != NULL) {

/* Unlock the lock so it's safe to free it */

if (self->rlock_count > 0)

PyThread_release_lock(self->rlock_lock);

PyThread_free_lock(self->rlock_lock);

}

Py_TYPE(self)->tp_free(self);

}

static PyObject *

rlock_acquire(rlockobject *self, PyObject *args, PyObject *kwds)

{

_PyTime_t timeout;

unsigned long tid;

PyLockStatus r = PY_LOCK_ACQUIRED;

if (lock_acquire_parse_args(args, kwds, &timeout) < 0)

return NULL;

tid = PyThread_get_thread_ident();

if (self->rlock_count > 0 && tid == self->rlock_owner) {

unsigned long count = self->rlock_count + 1;

if (count <= self->rlock_count) {

PyErr_SetString(PyExc_OverflowError,

"Internal lock count overflowed");

return NULL;

}

self->rlock_count = count;

Py_RETURN_TRUE;

}

r = acquire_timed(self->rlock_lock, timeout);

if (r == PY_LOCK_ACQUIRED) {

assert(self->rlock_count == 0);

self->rlock_owner = tid;

self->rlock_count = 1;

}

else if (r == PY_LOCK_INTR) {

return NULL;

}

return PyBool_FromLong(r == PY_LOCK_ACQUIRED);

}

PyDoc_STRVAR(rlock_acquire_doc,

"acquire(blocking=True) -> bool\n\

\n\

Lock the lock. `blocking` indicates whether we should wait\n\

for the lock to be available or not. If `blocking` is False\n\

and another thread holds the lock, the method will return False\n\

immediately. If `blocking` is True and another thread holds\n\

the lock, the method will wait for the lock to be released,\n\

take it and then return True.\n\

(note: the blocking operation is interruptible.)\n\

\n\

In all other cases, the method will return True immediately.\n\

Precisely, if the current thread already holds the lock, its\n\

internal counter is simply incremented. If nobody holds the lock,\n\

the lock is taken and its internal counter initialized to 1.");

static PyObject *

rlock_release(rlockobject *self, PyObject *Py_UNUSED(ignored))

{

unsigned long tid = PyThread_get_thread_ident();

if (self->rlock_count == 0 || self->rlock_owner != tid) {

PyErr_SetString(PyExc_RuntimeError,

"cannot release un-acquired lock");

return NULL;

}

if (--self->rlock_count == 0) {

self->rlock_owner = 0;

PyThread_release_lock(self->rlock_lock);

}

Py_RETURN_NONE;

}

PyDoc_STRVAR(rlock_release_doc,

"release()\n\

\n\

Release the lock, allowing another thread that is blocked waiting for\n\

the lock to acquire the lock. The lock must be in the locked state,\n\

and must be locked by the same thread that unlocks it; otherwise a\n\

`RuntimeError` is raised.\n\

\n\

Do note that if the lock was acquire()d several times in a row by the\n\

current thread, release() needs to be called as many times for the lock\n\

to be available for other threads.");

static PyObject *

rlock_acquire_restore(rlockobject *self, PyObject *args)

{

unsigned long owner;

unsigned long count;

int r = 1;

if (!PyArg_ParseTuple(args, "(kk):_acquire_restore", &count, &owner))

return NULL;

if (!PyThread_acquire_lock(self->rlock_lock, 0)) {

Py_BEGIN_ALLOW_THREADS

r = PyThread_acquire_lock(self->rlock_lock, 1);

Py_END_ALLOW_THREADS

}

if (!r) {

PyErr_SetString(ThreadError, "couldn't acquire lock");

return NULL;

}

assert(self->rlock_count == 0);

self->rlock_owner = owner;

self->rlock_count = count;

Py_RETURN_NONE;

}

PyDoc_STRVAR(rlock_acquire_restore_doc,

"_acquire_restore(state) -> None\n\

\n\

For internal use by `threading.Condition`.");

static PyObject *

rlock_release_save(rlockobject *self, PyObject *Py_UNUSED(ignored))

{

unsigned long owner;

unsigned long count;

if (self->rlock_count == 0) {

PyErr_SetString(PyExc_RuntimeError,

"cannot release un-acquired lock");

return NULL;

}

owner = self->rlock_owner;

count = self->rlock_count;

self->rlock_count = 0;

self->rlock_owner = 0;

PyThread_release_lock(self->rlock_lock);

return Py_BuildValue("kk", count, owner);

}

PyDoc_STRVAR(rlock_release_save_doc,

"_release_save() -> tuple\n\

\n\

For internal use by `threading.Condition`.");

static PyObject *

rlock_is_owned(rlockobject *self, PyObject *Py_UNUSED(ignored))

{

unsigned long tid = PyThread_get_thread_ident();

if (self->rlock_count > 0 && self->rlock_owner == tid) {

Py_RETURN_TRUE;

}

Py_RETURN_FALSE;

}

PyDoc_STRVAR(rlock_is_owned_doc,

"_is_owned() -> bool\n\

\n\

For internal use by `threading.Condition`.");

static PyObject *

rlock_new(PyTypeObject *type, PyObject *args, PyObject *kwds)

{

rlockobject *self = (rlockobject *) type->tp_alloc(type, 0);

if (self == NULL) {

return NULL;

}

self->in_weakreflist = NULL;

self->rlock_owner = 0;

self->rlock_count = 0;

self->rlock_lock = PyThread_allocate_lock();

if (self->rlock_lock == NULL) {

Py_DECREF(self);

PyErr_SetString(ThreadError, "can't allocate lock");

return NULL;

}

return (PyObject *) self;

}

static PyObject *

rlock_repr(rlockobject *self)

{

return PyUnicode_FromFormat("<%s %s object owner=%ld count=%lu at %p>",

self->rlock_count ? "locked" : "unlocked",

Py_TYPE(self)->tp_name, self->rlock_owner,

self->rlock_count, self);

}

#ifdef HAVE_FORK

static PyObject *

rlock__at_fork_reinit(rlockobject *self, PyObject *Py_UNUSED(args))

{

if (_PyThread_at_fork_reinit(&self->rlock_lock) < 0) {

PyErr_SetString(ThreadError, "failed to reinitialize lock at fork");

return NULL;

}

self->rlock_owner = 0;

self->rlock_count = 0;

Py_RETURN_NONE;

}

#endif /* HAVE_FORK */

static PyMethodDef rlock_methods[] = {

{"acquire", (PyCFunction)(void(*)(void))rlock_acquire,

METH_VARARGS | METH_KEYWORDS, rlock_acquire_doc},

{"release", (PyCFunction)rlock_release,

METH_NOARGS, rlock_release_doc},

{"_is_owned", (PyCFunction)rlock_is_owned,

METH_NOARGS, rlock_is_owned_doc},

{"_acquire_restore", (PyCFunction)rlock_acquire_restore,

METH_VARARGS, rlock_acquire_restore_doc},

{"_release_save", (PyCFunction)rlock_release_save,

METH_NOARGS, rlock_release_save_doc},

{"__enter__", (PyCFunction)(void(*)(void))rlock_acquire,

METH_VARARGS | METH_KEYWORDS, rlock_acquire_doc},

{"__exit__", (PyCFunction)rlock_release,

METH_VARARGS, rlock_release_doc},

#ifdef HAVE_FORK

{"_at_fork_reinit", (PyCFunction)rlock__at_fork_reinit,

METH_NOARGS, NULL},

#endif

{NULL, NULL} /* sentinel */

};

static PyTypeObject RLocktype = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

"_thread.RLock", /*tp_name*/

sizeof(rlockobject), /*tp_basicsize*/

0, /*tp_itemsize*/

/* methods */

(destructor)rlock_dealloc, /*tp_dealloc*/

0, /*tp_vectorcall_offset*/

0, /*tp_getattr*/

0, /*tp_setattr*/

0, /*tp_as_async*/

(reprfunc)rlock_repr, /*tp_repr*/

0, /*tp_as_number*/

0, /*tp_as_sequence*/

0, /*tp_as_mapping*/

0, /*tp_hash*/

0, /*tp_call*/

0, /*tp_str*/

0, /*tp_getattro*/

0, /*tp_setattro*/

0, /*tp_as_buffer*/

Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */

0, /*tp_doc*/

0, /*tp_traverse*/

0, /*tp_clear*/

0, /*tp_richcompare*/

offsetof(rlockobject, in_weakreflist), /*tp_weaklistoffset*/

0, /*tp_iter*/

0, /*tp_iternext*/

rlock_methods, /*tp_methods*/

0, /* tp_members */

0, /* tp_getset */

0, /* tp_base */

0, /* tp_dict */

0, /* tp_descr_get */

0, /* tp_descr_set */

0, /* tp_dictoffset */

0, /* tp_init */

PyType_GenericAlloc, /* tp_alloc */

rlock_new /* tp_new */

};

static lockobject *

newlockobject(void)

{

lockobject *self;

self = PyObject_New(lockobject, &Locktype);

if (self == NULL)

return NULL;

self->lock_lock = PyThread_allocate_lock();

self->locked = 0;

self->in_weakreflist = NULL;

if (self->lock_lock == NULL) {

Py_DECREF(self);

PyErr_SetString(ThreadError, "can't allocate lock");

return NULL;

}

return self;

}

/* Thread-local objects */

/* Quick overview:

We need to be able to reclaim reference cycles as soon as possible

(both when a thread is being terminated, or a thread-local object

becomes unreachable from user data). Constraints:

- it must not be possible for thread-state dicts to be involved in

reference cycles (otherwise the cyclic GC will refuse to consider

objects referenced from a reachable thread-state dict, even though

local_dealloc would clear them)

- the death of a thread-state dict must still imply destruction of the

corresponding local dicts in all thread-local objects.

Our implementation uses small "localdummy" objects in order to break

the reference chain. These trivial objects are hashable (using the

default scheme of identity hashing) and weakrefable.

Each thread-state holds a separate localdummy for each local object

(as a /strong reference/),

and each thread-local object holds a dict mapping /weak references/

of localdummies to local dicts.

Therefore:

- only the thread-state dict holds a strong reference to the dummies

- only the thread-local object holds a strong reference to the local dicts

- only outside objects (application- or library-level) hold strong

references to the thread-local objects

- as soon as a thread-state dict is destroyed, the weakref callbacks of all

dummies attached to that thread are called, and destroy the corresponding

local dicts from thread-local objects

- as soon as a thread-local object is destroyed, its local dicts are

destroyed and its dummies are manually removed from all thread states

- the GC can do its work correctly when a thread-local object is dangling,

without any interference from the thread-state dicts

As an additional optimization, each localdummy holds a borrowed reference

to the corresponding localdict. This borrowed reference is only used

by the thread-local object which has created the localdummy, which should

guarantee that the localdict still exists when accessed.

typedef struct {

PyObject_HEAD

PyObject *localdict; /* Borrowed reference! */

PyObject *weakreflist; /* List of weak references to self */

} localdummyobject;

static void

localdummy_dealloc(localdummyobject *self)

{

if (self->weakreflist != NULL)

PyObject_ClearWeakRefs((PyObject *) self);

Py_TYPE(self)->tp_free((PyObject*)self);

}

static PyTypeObject localdummytype = {

PyVarObject_HEAD_INIT(NULL, 0)

/* tp_name */ "_thread._localdummy",

/* tp_basicsize */ sizeof(localdummyobject),

/* tp_itemsize */ 0,

/* tp_dealloc */ (destructor)localdummy_dealloc,

/* tp_vectorcall_offset */ 0,

/* tp_getattr */ 0,

/* tp_setattr */ 0,

/* tp_as_async */ 0,

/* tp_repr */ 0,

/* tp_as_number */ 0,

/* tp_as_sequence */ 0,

/* tp_as_mapping */ 0,

/* tp_hash */ 0,

/* tp_call */ 0,

/* tp_str */ 0,

/* tp_getattro */ 0,

/* tp_setattro */ 0,

/* tp_as_buffer */ 0,

/* tp_flags */ Py_TPFLAGS_DEFAULT,

/* tp_doc */ "Thread-local dummy",

/* tp_traverse */ 0,

/* tp_clear */ 0,

/* tp_richcompare */ 0,

/* tp_weaklistoffset */ offsetof(localdummyobject, weakreflist)

};

typedef struct {

PyObject_HEAD

PyObject *key;

PyObject *args;

PyObject *kw;

PyObject *weakreflist; /* List of weak references to self */

/* A {localdummy weakref -> localdict} dict */

PyObject *dummies;

/* The callback for weakrefs to localdummies */

PyObject *wr_callback;

} localobject;

/* Forward declaration */

static PyObject *_ldict(localobject *self);

static PyObject *_localdummy_destroyed(PyObject *meth_self, PyObject *dummyweakref);

/* Create and register the dummy for the current thread.

Returns a borrowed reference of the corresponding local dict */

static PyObject *

_local_create_dummy(localobject *self)

{

PyObject *tdict, *ldict = NULL, *wr = NULL;

localdummyobject *dummy = NULL;

int r;

tdict = PyThreadState_GetDict();

if (tdict == NULL) {

PyErr_SetString(PyExc_SystemError,

"Couldn't get thread-state dictionary");

goto err;

}

ldict = PyDict_New();

if (ldict == NULL)

goto err;

dummy = (localdummyobject *) localdummytype.tp_alloc(&localdummytype, 0);

if (dummy == NULL)

goto err;

dummy->localdict = ldict;

wr = PyWeakref_NewRef((PyObject *) dummy, self->wr_callback);

if (wr == NULL)

goto err;

/* As a side-effect, this will cache the weakref's hash before the

dummy gets deleted */

r = PyDict_SetItem(self->dummies, wr, ldict);

if (r < 0)

goto err;

Py_CLEAR(wr);

r = PyDict_SetItem(tdict, self->key, (PyObject *) dummy);

if (r < 0)

goto err;

Py_CLEAR(dummy);

Py_DECREF(ldict);

return ldict;

err:

Py_XDECREF(ldict);

Py_XDECREF(wr);

Py_XDECREF(dummy);

return NULL;

}

static PyObject *

local_new(PyTypeObject *type, PyObject *args, PyObject *kw)

{

localobject *self;

PyObject *wr;

static PyMethodDef wr_callback_def = {

"_localdummy_destroyed", (PyCFunction) _localdummy_destroyed, METH_O

};

if (type->tp_init == PyBaseObject_Type.tp_init) {

int rc = 0;

if (args != NULL)

rc = PyObject_IsTrue(args);

if (rc == 0 && kw != NULL)

rc = PyObject_IsTrue(kw);

if (rc != 0) {

if (rc > 0)

PyErr_SetString(PyExc_TypeError,

"Initialization arguments are not supported");

return NULL;

}

self = (localobject *)type->tp_alloc(type, 0);

if (self == NULL)

return NULL;

Py_XINCREF(args);

self->args = args;

Py_XINCREF(kw);

self->kw = kw;

self->key = PyUnicode_FromFormat("thread.local.%p", self);

if (self->key == NULL)

goto err;

self->dummies = PyDict_New();

if (self->dummies == NULL)

goto err;

/* We use a weak reference to self in the callback closure

in order to avoid spurious reference cycles */

wr = PyWeakref_NewRef((PyObject *) self, NULL);

if (wr == NULL)

goto err;

self->wr_callback = PyCFunction_NewEx(&wr_callback_def, wr, NULL);

Py_DECREF(wr);

if (self->wr_callback == NULL)

goto err;

if (_local_create_dummy(self) == NULL)

goto err;

return (PyObject *)self;

err:

Py_DECREF(self);

return NULL;

}

static int

local_traverse(localobject *self, visitproc visit, void *arg)

{

Py_VISIT(self->args);

Py_VISIT(self->kw);

Py_VISIT(self->dummies);

return 0;

}

static int

local_clear(localobject *self)

{

PyThreadState *tstate;

Py_CLEAR(self->args);

Py_CLEAR(self->kw);

Py_CLEAR(self->dummies);

Py_CLEAR(self->wr_callback);

/* Remove all strong references to dummies from the thread states */

if (self->key

&& (tstate = PyThreadState_Get())

&& tstate->interp) {

for(tstate = PyInterpreterState_ThreadHead(tstate->interp);

tstate;

tstate = PyThreadState_Next(tstate))

if (tstate->dict && PyDict_GetItem(tstate->dict, self->key)) {

if (PyDict_DelItem(tstate->dict, self->key)) {

PyErr_Clear();

}

return 0;

}

static void

local_dealloc(localobject *self)

{

/* Weakrefs must be invalidated right now, otherwise they can be used

from code called below, which is very dangerous since Py_REFCNT(self) == 0 */

if (self->weakreflist != NULL)

PyObject_ClearWeakRefs((PyObject *) self);

PyObject_GC_UnTrack(self);

local_clear(self);

Py_XDECREF(self->key);

Py_TYPE(self)->tp_free((PyObject*)self);

}

/* Returns a borrowed reference to the local dict, creating it if necessary */

static PyObject *

_ldict(localobject *self)

{

PyObject *tdict, *ldict, *dummy;

tdict = PyThreadState_GetDict();

if (tdict == NULL) {

PyErr_SetString(PyExc_SystemError,

"Couldn't get thread-state dictionary");

return NULL;

}

dummy = PyDict_GetItemWithError(tdict, self->key);

if (dummy == NULL) {

if (PyErr_Occurred()) {

return NULL;

}

ldict = _local_create_dummy(self);

if (ldict == NULL)

return NULL;

if (Py_TYPE(self)->tp_init != PyBaseObject_Type.tp_init &&

Py_TYPE(self)->tp_init((PyObject*)self,

self->args, self->kw) < 0) {

/* we need to get rid of ldict from thread so

we create a new one the next time we do an attr

access */

PyDict_DelItem(tdict, self->key);

return NULL;

}

else {

assert(Py_IS_TYPE(dummy, &localdummytype));

ldict = ((localdummyobject *) dummy)->localdict;

}

return ldict;

}

static int

local_setattro(localobject *self, PyObject *name, PyObject *v)

{

PyObject *ldict;

int r;

ldict = _ldict(self);

if (ldict == NULL)

return -1;

r = PyObject_RichCompareBool(name, str_dict, Py_EQ);

if (r == 1) {

PyErr_Format(PyExc_AttributeError,

"'%.50s' object attribute '%U' is read-only",

Py_TYPE(self)->tp_name, name);

return -1;

}

if (r == -1)

return -1;

return _PyObject_GenericSetAttrWithDict((PyObject *)self, name, v, ldict);

}

static PyObject *local_getattro(localobject *, PyObject *);

static PyTypeObject localtype = {

PyVarObject_HEAD_INIT(NULL, 0)

/* tp_name */ "_thread._local",

/* tp_basicsize */ sizeof(localobject),

/* tp_itemsize */ 0,

/* tp_dealloc */ (destructor)local_dealloc,

/* tp_vectorcall_offset */ 0,

/* tp_getattr */ 0,

/* tp_setattr */ 0,

/* tp_as_async */ 0,

/* tp_repr */ 0,

/* tp_as_number */ 0,

/* tp_as_sequence */ 0,

/* tp_as_mapping */ 0,

/* tp_hash */ 0,

/* tp_call */ 0,

/* tp_str */ 0,

/* tp_getattro */ (getattrofunc)local_getattro,

/* tp_setattro */ (setattrofunc)local_setattro,

/* tp_as_buffer */ 0,

/* tp_flags */ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE

| Py_TPFLAGS_HAVE_GC,

/* tp_doc */ "Thread-local data",

/* tp_traverse */ (traverseproc)local_traverse,

/* tp_clear */ (inquiry)local_clear,

/* tp_richcompare */ 0,

/* tp_weaklistoffset */ offsetof(localobject, weakreflist),

/* tp_iter */ 0,

/* tp_iternext */ 0,

/* tp_methods */ 0,

/* tp_members */ 0,

/* tp_getset */ 0,

/* tp_base */ 0,

/* tp_dict */ 0, /* internal use */

/* tp_descr_get */ 0,

/* tp_descr_set */ 0,

/* tp_dictoffset */ 0,

/* tp_init */ 0,

/* tp_alloc */ 0,

/* tp_new */ local_new,

/* tp_free */ 0, /* Low-level free-mem routine */

/* tp_is_gc */ 0, /* For PyObject_IS_GC */

};

static PyObject *

local_getattro(localobject *self, PyObject *name)

{

PyObject *ldict, *value;

int r;

ldict = _ldict(self);

if (ldict == NULL)

return NULL;

r = PyObject_RichCompareBool(name, str_dict, Py_EQ);

if (r == 1) {

Py_INCREF(ldict);

return ldict;

}

if (r == -1)

return NULL;

if (!Py_IS_TYPE(self, &localtype))

/* use generic lookup for subtypes */

return _PyObject_GenericGetAttrWithDict(

(PyObject *)self, name, ldict, 0);

/* Optimization: just look in dict ourselves */

value = PyDict_GetItemWithError(ldict, name);

if (value != NULL) {

Py_INCREF(value);

return value;

}

else if (PyErr_Occurred()) {

return NULL;

}

/* Fall back on generic to get __class__ and __dict__ */

return _PyObject_GenericGetAttrWithDict(

(PyObject *)self, name, ldict, 0);

}

/* Called when a dummy is destroyed. */

static PyObject *

_localdummy_destroyed(PyObject *localweakref, PyObject *dummyweakref)

{

PyObject *obj;

localobject *self;

assert(PyWeakref_CheckRef(localweakref));

obj = PyWeakref_GET_OBJECT(localweakref);

if (obj == Py_None)

Py_RETURN_NONE;

Py_INCREF(obj);

assert(PyObject_TypeCheck(obj, &localtype));

View remainder of file in raw view

cpython/Modules/_threadmodule.c at master · python-emscripten/cpython · GitHub

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