cpython/Python/pystate.c at 3.5 · python/cpython · GitHub

Repository navigation

History

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

695

696

697

698

699

700

701

702

703

704

705

706

707

708

709

710

711

712

713

714

715

716

717

718

719

720

721

722

723

724

725

726

727

728

729

730

731

732

733

734

735

736

737

738

739

740

741

742

743

744

745

746

747

748

749

750

751

752

753

754

755

756

757

758

759

760

761

762

763

764

765

766

767

768

769

770

771

772

773

774

775

776

777

778

779

780

781

782

783

784

785

786

787

788

789

790

791

792

793

794

795

796

797

798

799

800

801

802

803

804

805

806

807

808

809

810

811

812

813

814

815

816

817

818

819

820

821

822

823

824

825

826

827

828

829

830

831

832

833

834

835

836

837

838

839

840

841

842

843

844

845

846

847

848

849

850

851

852

853

854

855

856

857

858

859

860

861

862

863

864

865

866

867

868

869

870

871

872

873

874

875

/* Thread and interpreter state structures and their interfaces */

#include "Python.h"

#define GET_TSTATE() \

((PyThreadState*)_Py_atomic_load_relaxed(&_PyThreadState_Current))

#define SET_TSTATE(value) \

_Py_atomic_store_relaxed(&_PyThreadState_Current, (Py_uintptr_t)(value))

#define GET_INTERP_STATE() \

(GET_TSTATE()->interp)

/* --------------------------------------------------------------------------

CAUTION

Always use PyMem_RawMalloc() and PyMem_RawFree() directly in this file. A

number of these functions are advertised as safe to call when the GIL isn't

held, and in a debug build Python redirects (e.g.) PyMem_NEW (etc) to Python's

debugging obmalloc functions. Those aren't thread-safe (they rely on the GIL

to avoid the expense of doing their own locking).

-------------------------------------------------------------------------- */

#ifdef HAVE_DLOPEN

#ifdef HAVE_DLFCN_H

#include <dlfcn.h>

#endif

#ifndef RTLD_LAZY

#define RTLD_LAZY 1

#endif

#ifdef __cplusplus

extern "C" {

#endif

#ifdef WITH_THREAD

#include "pythread.h"

static PyThread_type_lock head_mutex = NULL; /* Protects interp->tstate_head */

#define HEAD_INIT() (void)(head_mutex || (head_mutex = PyThread_allocate_lock()))

#define HEAD_LOCK() PyThread_acquire_lock(head_mutex, WAIT_LOCK)

#define HEAD_UNLOCK() PyThread_release_lock(head_mutex)

/* The single PyInterpreterState used by this process'

GILState implementation

static PyInterpreterState *autoInterpreterState = NULL;

static int autoTLSkey = 0;

#else

#define HEAD_INIT() /* Nothing */

#define HEAD_LOCK() /* Nothing */

#define HEAD_UNLOCK() /* Nothing */

#endif

static PyInterpreterState *interp_head = NULL;

/* Assuming the current thread holds the GIL, this is the

PyThreadState for the current thread. */

_Py_atomic_address _PyThreadState_Current = {0};

PyThreadFrameGetter _PyThreadState_GetFrame = NULL;

#ifdef WITH_THREAD

static void _PyGILState_NoteThreadState(PyThreadState* tstate);

#endif

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

#ifdef WITH_TSC

interp->tscdump = 0;

#endif

HEAD_LOCK();

interp->next = interp_head;

interp_head = interp;

HEAD_UNLOCK();

}

return interp;

}

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_by_index);

Py_CLEAR(interp->sysdict);

Py_CLEAR(interp->builtins);

Py_CLEAR(interp->builtins_copy);

Py_CLEAR(interp->importlib);

}

static void

zapthreads(PyInterpreterState *interp)

{

PyThreadState *p;

/* No need to lock the mutex here because this should only happen

when the threads are all really dead (XXX famous last words). */

while ((p = interp->tstate_head) != NULL) {

PyThreadState_Delete(p);

}

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

}

/* Default implementation for _PyThreadState_GetFrame */

static struct _frame *

threadstate_getframe(PyThreadState *self)

{

return self->frame;

}

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->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;

tstate->coroutine_wrapper = NULL;

tstate->in_coroutine_wrapper = 0;

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;

}

PyThreadState *

PyThreadState_New(PyInterpreterState *interp)

{

return new_threadstate(interp, 1);

}

PyThreadState *

_PyThreadState_Prealloc(PyInterpreterState *interp)

{

return new_threadstate(interp, 0);

}

void

_PyThreadState_Init(PyThreadState *tstate)

{

#ifdef WITH_THREAD

_PyGILState_NoteThreadState(tstate);

#endif

}

PyObject*

PyState_FindModule(struct PyModuleDef* module)

{

Py_ssize_t index = module->m_base.m_index;

PyInterpreterState *state = GET_INTERP_STATE();

PyObject *res;

if (module->m_slots) {

return NULL;

}

if (index == 0)

return NULL;

if (state->modules_by_index == NULL)

return NULL;

if (index >= PyList_GET_SIZE(state->modules_by_index))

return NULL;

res = PyList_GET_ITEM(state->modules_by_index, index);

return res==Py_None ? NULL : res;

}

int

_PyState_AddModule(PyObject* module, struct PyModuleDef* def)

{

PyInterpreterState *state;

if (!def) {

assert(PyErr_Occurred());

return -1;

}

if (def->m_slots) {

PyErr_SetString(PyExc_SystemError,

"PyState_AddModule called on module with slots");

return -1;

}

state = GET_INTERP_STATE();

if (!state->modules_by_index) {

state->modules_by_index = PyList_New(0);

if (!state->modules_by_index)

return -1;

}

while(PyList_GET_SIZE(state->modules_by_index) <= def->m_base.m_index)

if (PyList_Append(state->modules_by_index, Py_None) < 0)

return -1;

Py_INCREF(module);

return PyList_SetItem(state->modules_by_index,

def->m_base.m_index, module);

}

int

PyState_AddModule(PyObject* module, struct PyModuleDef* def)

{

Py_ssize_t index;

PyInterpreterState *state = GET_INTERP_STATE();

if (!def) {

Py_FatalError("PyState_AddModule: Module Definition is NULL");

return -1;

}

index = def->m_base.m_index;

if (state->modules_by_index) {

if(PyList_GET_SIZE(state->modules_by_index) >= index) {

if(module == PyList_GET_ITEM(state->modules_by_index, index)) {

Py_FatalError("PyState_AddModule: Module already added!");

return -1;

}

return _PyState_AddModule(module, def);

}

int

PyState_RemoveModule(struct PyModuleDef* def)

{

PyInterpreterState *state;

Py_ssize_t index = def->m_base.m_index;

if (def->m_slots) {

PyErr_SetString(PyExc_SystemError,

"PyState_RemoveModule called on module with slots");

return -1;

}

state = GET_INTERP_STATE();

if (index == 0) {

Py_FatalError("PyState_RemoveModule: Module index invalid.");

return -1;

}

if (state->modules_by_index == NULL) {

Py_FatalError("PyState_RemoveModule: Interpreters module-list not acessible.");

return -1;

}

if (index > PyList_GET_SIZE(state->modules_by_index)) {

Py_FatalError("PyState_RemoveModule: Module index out of bounds.");

return -1;

}

return PyList_SetItem(state->modules_by_index, index, Py_None);

}

/* used by import.c:PyImport_Cleanup */

void

_PyState_ClearModules(void)

{

PyInterpreterState *state = GET_INTERP_STATE();

if (state->modules_by_index) {

Py_ssize_t i;

for (i = 0; i < PyList_GET_SIZE(state->modules_by_index); i++) {

PyObject *m = PyList_GET_ITEM(state->modules_by_index, i);

if (PyModule_Check(m)) {

/* cleanup the saved copy of module dicts */

PyModuleDef *md = PyModule_GetDef(m);

if (md)

Py_CLEAR(md->m_base.m_copy);

}

/* Setting modules_by_index to NULL could be dangerous, so we

clear the list instead. */

if (PyList_SetSlice(state->modules_by_index,

0, PyList_GET_SIZE(state->modules_by_index),

NULL))

PyErr_WriteUnraisable(state->modules_by_index);

}

void

PyThreadState_Clear(PyThreadState *tstate)

{

if (Py_VerboseFlag && tstate->frame != NULL)

fprintf(stderr,

"PyThreadState_Clear: warning: thread still has a frame\n");

Py_CLEAR(tstate->frame);

Py_CLEAR(tstate->dict);

Py_CLEAR(tstate->async_exc);

Py_CLEAR(tstate->curexc_type);

Py_CLEAR(tstate->curexc_value);

Py_CLEAR(tstate->curexc_traceback);

Py_CLEAR(tstate->exc_type);

Py_CLEAR(tstate->exc_value);

Py_CLEAR(tstate->exc_traceback);

tstate->c_profilefunc = NULL;

tstate->c_tracefunc = NULL;

Py_CLEAR(tstate->c_profileobj);

Py_CLEAR(tstate->c_traceobj);

Py_CLEAR(tstate->coroutine_wrapper);

}

/* 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);

}

void

PyThreadState_Delete(PyThreadState *tstate)

{

if (tstate == GET_TSTATE())

Py_FatalError("PyThreadState_Delete: tstate is still current");

#ifdef WITH_THREAD

if (autoInterpreterState && PyThread_get_key_value(autoTLSkey) == tstate)

PyThread_delete_key_value(autoTLSkey);

#endif /* WITH_THREAD */

tstate_delete_common(tstate);

}

#ifdef WITH_THREAD

void

PyThreadState_DeleteCurrent()

{

PyThreadState *tstate = GET_TSTATE();

if (tstate == NULL)

Py_FatalError(

"PyThreadState_DeleteCurrent: no current tstate");

SET_TSTATE(NULL);

if (autoInterpreterState && PyThread_get_key_value(autoTLSkey) == tstate)

PyThread_delete_key_value(autoTLSkey);

tstate_delete_common(tstate);

PyEval_ReleaseLock();

}

#endif /* WITH_THREAD */

* 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);

}

PyThreadState *

_PyThreadState_UncheckedGet(void)

{

return GET_TSTATE();

}

PyThreadState *

PyThreadState_Get(void)

{

PyThreadState *tstate = GET_TSTATE();

if (tstate == NULL)

Py_FatalError("PyThreadState_Get: no current thread");

return tstate;

}

PyThreadState *

PyThreadState_Swap(PyThreadState *newts)

{

PyThreadState *oldts = GET_TSTATE();

SET_TSTATE(newts);

/* It should not be possible for more than one thread state

to be used for a thread. Check this the best we can in debug

builds.

#if defined(Py_DEBUG) && defined(WITH_THREAD)

if (newts) {

/* This can be called from PyEval_RestoreThread(). Similar

to it, we need to ensure errno doesn't change.

int err = errno;

PyThreadState *check = PyGILState_GetThisThreadState();

if (check && check->interp == newts->interp && check != newts)

Py_FatalError("Invalid thread state for this thread");

errno = err;

}

#endif

return oldts;

}

/* An extension mechanism to store arbitrary additional per-thread state.

PyThreadState_GetDict() returns a dictionary that can be used to hold such

state; the caller should pick a unique key and store its state there. If

PyThreadState_GetDict() returns NULL, an exception has *not* been raised

and the caller should assume no per-thread state is available. */

PyObject *

PyThreadState_GetDict(void)

{

PyThreadState *tstate = GET_TSTATE();

if (tstate == NULL)

return NULL;

if (tstate->dict == NULL) {

PyObject *d;

tstate->dict = d = PyDict_New();

if (d == NULL)

PyErr_Clear();

}

return tstate->dict;

}

/* Asynchronously raise an exception in a thread.

Requested by Just van Rossum and Alex Martelli.

To prevent naive misuse, you must write your own extension

to call this, or use ctypes. Must be called with the GIL held.

Returns the number of tstates modified (normally 1, but 0 if `id` didn't

match any known thread id). Can be called with exc=NULL to clear an

existing async exception. This raises no exceptions. */

int

PyThreadState_SetAsyncExc(long id, PyObject *exc) {

PyInterpreterState *interp = GET_INTERP_STATE();

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);

_PyEval_SignalAsyncExc();

return 1;

}

HEAD_UNLOCK();

return 0;

}

/* Routines for advanced debuggers, requested by David Beazley.

Don't use unless you know what you are doing! */

PyInterpreterState *

PyInterpreterState_Head(void)

{

return interp_head;

}

PyInterpreterState *

PyInterpreterState_Next(PyInterpreterState *interp) {

return interp->next;

}

PyThreadState *

PyInterpreterState_ThreadHead(PyInterpreterState *interp) {

return interp->tstate_head;

}

PyThreadState *

PyThreadState_Next(PyThreadState *tstate) {

return tstate->next;

}

/* 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 = PyLong_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;

}

/* Python "auto thread state" API. */

#ifdef WITH_THREAD

/* Keep this as a static, as it is not reliable! It can only

ever be compared to the state for the *current* thread.

* If not equal, then it doesn't matter that the actual

value may change immediately after comparison, as it can't

possibly change to the current thread's state.

* If equal, then the current thread holds the lock, so the value can't

change until we yield the lock.

static int

PyThreadState_IsCurrent(PyThreadState *tstate)

{

/* Must be the tstate for this thread */

assert(PyGILState_GetThisThreadState()==tstate);

return tstate == GET_TSTATE();

}

/* Internal initialization/finalization functions called by

Py_Initialize/Py_Finalize

void

_PyGILState_Init(PyInterpreterState *i, PyThreadState *t)

{

assert(i && t); /* must init with valid states */

autoTLSkey = PyThread_create_key();

if (autoTLSkey == -1)

Py_FatalError("Could not allocate TLS entry");

autoInterpreterState = i;

assert(PyThread_get_key_value(autoTLSkey) == NULL);

assert(t->gilstate_counter == 0);

_PyGILState_NoteThreadState(t);

}

void

_PyGILState_Fini(void)

{

PyThread_delete_key(autoTLSkey);

autoInterpreterState = NULL;

}

/* Reset the TLS key - called by PyOS_AfterFork().

* This should not be necessary, but some - buggy - pthread implementations

* don't reset TLS upon fork(), see issue #10517.

void

_PyGILState_Reinit(void)

{

PyThreadState *tstate = PyGILState_GetThisThreadState();

PyThread_delete_key(autoTLSkey);

if ((autoTLSkey = PyThread_create_key()) == -1)

Py_FatalError("Could not allocate TLS entry");

/* If the thread had an associated auto thread state, reassociate it with

* the new key. */

if (tstate && PyThread_set_key_value(autoTLSkey, (void *)tstate) < 0)

Py_FatalError("Couldn't create autoTLSkey mapping");

}

/* When a thread state is created for a thread by some mechanism other than

PyGILState_Ensure, it's important that the GILState machinery knows about

it so it doesn't try to create another thread state for the thread (this is

a better fix for SF bug #1010677 than the first one attempted).

static void

_PyGILState_NoteThreadState(PyThreadState* tstate)

{

/* If autoTLSkey isn't initialized, this must be the very first

threadstate created in Py_Initialize(). Don't do anything for now

(we'll be back here when _PyGILState_Init is called). */

if (!autoInterpreterState)

return;

/* Stick the thread state for this thread in thread local storage.

The only situation where you can legitimately have more than one

thread state for an OS level thread is when there are multiple

interpreters.

You shouldn't really be using the PyGILState_ APIs anyway (see issues

#10915 and #15751).

The first thread state created for that given OS level thread will

"win", which seems reasonable behaviour.

if (PyThread_get_key_value(autoTLSkey) == NULL) {

if (PyThread_set_key_value(autoTLSkey, (void *)tstate) < 0)

Py_FatalError("Couldn't create autoTLSkey mapping");

}

/* PyGILState_Release must not try to delete this thread state. */

tstate->gilstate_counter = 1;

}

/* The public functions */

PyThreadState *

PyGILState_GetThisThreadState(void)

{

if (autoInterpreterState == NULL)

return NULL;

return (PyThreadState *)PyThread_get_key_value(autoTLSkey);

}

int

PyGILState_Check(void)

{

PyThreadState *tstate = GET_TSTATE();

return tstate && (tstate == PyGILState_GetThisThreadState());

}

PyGILState_STATE

PyGILState_Ensure(void)

{

int current;

PyThreadState *tcur;

/* Note that we do not auto-init Python here - apart from

potential races with 2 threads auto-initializing, pep-311

spells out other issues. Embedders are expected to have

called Py_Initialize() and usually PyEval_InitThreads().

assert(autoInterpreterState); /* Py_Initialize() hasn't been called! */

tcur = (PyThreadState *)PyThread_get_key_value(autoTLSkey);

if (tcur == NULL) {

/* At startup, Python has no concrete GIL. If PyGILState_Ensure() is

called from a new thread for the first time, we need the create the

GIL. */

PyEval_InitThreads();

/* Create a new thread state for this thread */

tcur = PyThreadState_New(autoInterpreterState);

if (tcur == NULL)

Py_FatalError("Couldn't create thread-state for new thread");

/* This is our thread state! We'll need to delete it in the

matching call to PyGILState_Release(). */

tcur->gilstate_counter = 0;

current = 0; /* new thread state is never current */

}

else

current = PyThreadState_IsCurrent(tcur);

if (current == 0)

PyEval_RestoreThread(tcur);

/* Update our counter in the thread-state - no need for locks:

- tcur will remain valid as we hold the GIL.

- the counter is safe as we are the only thread "allowed"

to modify this value

++tcur->gilstate_counter;

return current ? PyGILState_LOCKED : PyGILState_UNLOCKED;

}

void

PyGILState_Release(PyGILState_STATE oldstate)

{

PyThreadState *tcur = (PyThreadState *)PyThread_get_key_value(

autoTLSkey);

if (tcur == NULL)

Py_FatalError("auto-releasing thread-state, "

"but no thread-state for this thread");

/* We must hold the GIL and have our thread state current */

/* XXX - remove the check - the assert should be fine,

but while this is very new (April 2003), the extra check

by release-only users can't hurt.

if (! PyThreadState_IsCurrent(tcur))

Py_FatalError("This thread state must be current when releasing");

assert(PyThreadState_IsCurrent(tcur));

--tcur->gilstate_counter;

assert(tcur->gilstate_counter >= 0); /* illegal counter value */

/* If we're going to destroy this thread-state, we must

* clear it while the GIL is held, as destructors may run.

if (tcur->gilstate_counter == 0) {

/* can't have been locked when we created it */

assert(oldstate == PyGILState_UNLOCKED);

PyThreadState_Clear(tcur);

/* Delete the thread-state. Note this releases the GIL too!

* It's vital that the GIL be held here, to avoid shutdown

* races; see bugs 225673 and 1061968 (that nasty bug has a

* habit of coming back).

PyThreadState_DeleteCurrent();

}

/* Release the lock if necessary */

else if (oldstate == PyGILState_UNLOCKED)

PyEval_SaveThread();

}

#endif /* WITH_THREAD */

#ifdef __cplusplus

}

#endif

cpython/Python/pystate.c at 3.5 · python/cpython · GitHub

Repository navigation

Expand file tree

Breadcrumbs

pystate.c

Latest commit

History

Breadcrumbs

pystate.c

File metadata and controls