1 #include "pycore_interp.h" // _PyInterpreterState.threads.stacksize
2
3 /* This code implemented by Dag.Gruneau@elsa.preseco.comm.se */
4 /* Fast NonRecursiveMutex support by Yakov Markovitch, markovitch@iso.ru */
5 /* Eliminated some memory leaks, gsw@agere.com */
6
7 #include <windows.h>
8 #include <limits.h>
9 #ifdef HAVE_PROCESS_H
10 #include <process.h>
11 #endif
12
13 /* options */
14 #ifndef _PY_USE_CV_LOCKS
15 #define _PY_USE_CV_LOCKS 1 /* use locks based on cond vars */
16 #endif
17
18 /* Now, define a non-recursive mutex using either condition variables
19 * and critical sections (fast) or using operating system mutexes
20 * (slow)
21 */
22
23 #if _PY_USE_CV_LOCKS
24
25 #include "condvar.h"
26
27 typedef struct _NRMUTEX
28 {
29 PyMUTEX_T cs;
30 PyCOND_T cv;
31 int locked;
32 } NRMUTEX;
33 typedef NRMUTEX *PNRMUTEX;
34
35 static PNRMUTEX
36 AllocNonRecursiveMutex(void)
37 {
38 PNRMUTEX m = (PNRMUTEX)PyMem_RawMalloc(sizeof(NRMUTEX));
39 if (!m)
40 return NULL;
41 if (PyCOND_INIT(&m->cv))
42 goto fail;
43 if (PyMUTEX_INIT(&m->cs)) {
44 PyCOND_FINI(&m->cv);
45 goto fail;
46 }
47 m->locked = 0;
48 return m;
49 fail:
50 PyMem_RawFree(m);
51 return NULL;
52 }
53
54 static VOID
55 FreeNonRecursiveMutex(PNRMUTEX mutex)
56 {
57 if (mutex) {
58 PyCOND_FINI(&mutex->cv);
59 PyMUTEX_FINI(&mutex->cs);
60 PyMem_RawFree(mutex);
61 }
62 }
63
64 static DWORD
65 EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
66 {
67 DWORD result = WAIT_OBJECT_0;
68 if (PyMUTEX_LOCK(&mutex->cs))
69 return WAIT_FAILED;
70 if (milliseconds == INFINITE) {
71 while (mutex->locked) {
72 if (PyCOND_WAIT(&mutex->cv, &mutex->cs)) {
73 result = WAIT_FAILED;
74 break;
75 }
76 }
77 } else if (milliseconds != 0) {
78 /* wait at least until the deadline */
79 _PyTime_t nanoseconds = _PyTime_FromNanoseconds((_PyTime_t)milliseconds * 1000000);
80 _PyTime_t deadline = _PyTime_Add(_PyTime_GetPerfCounter(), nanoseconds);
81 while (mutex->locked) {
82 _PyTime_t microseconds = _PyTime_AsMicroseconds(nanoseconds,
83 _PyTime_ROUND_TIMEOUT);
84 if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, microseconds) < 0) {
85 result = WAIT_FAILED;
86 break;
87 }
88 nanoseconds = deadline - _PyTime_GetPerfCounter();
89 if (nanoseconds <= 0) {
90 break;
91 }
92 }
93 }
94 if (!mutex->locked) {
95 mutex->locked = 1;
96 result = WAIT_OBJECT_0;
97 } else if (result == WAIT_OBJECT_0)
98 result = WAIT_TIMEOUT;
99 /* else, it is WAIT_FAILED */
100 PyMUTEX_UNLOCK(&mutex->cs); /* must ignore result here */
101 return result;
102 }
103
104 static BOOL
105 LeaveNonRecursiveMutex(PNRMUTEX mutex)
106 {
107 BOOL result;
108 if (PyMUTEX_LOCK(&mutex->cs))
109 return FALSE;
110 mutex->locked = 0;
111 /* condvar APIs return 0 on success. We need to return TRUE on success. */
112 result = !PyCOND_SIGNAL(&mutex->cv);
113 PyMUTEX_UNLOCK(&mutex->cs);
114 return result;
115 }
116
117 #else /* if ! _PY_USE_CV_LOCKS */
118
119 /* NR-locks based on a kernel mutex */
120 #define PNRMUTEX HANDLE
121
122 static PNRMUTEX
123 AllocNonRecursiveMutex(void)
124 {
125 return CreateSemaphore(NULL, 1, 1, NULL);
126 }
127
128 static VOID
129 FreeNonRecursiveMutex(PNRMUTEX mutex)
130 {
131 /* No in-use check */
132 CloseHandle(mutex);
133 }
134
135 static DWORD
136 EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
137 {
138 return WaitForSingleObjectEx(mutex, milliseconds, FALSE);
139 }
140
141 static BOOL
142 LeaveNonRecursiveMutex(PNRMUTEX mutex)
143 {
144 return ReleaseSemaphore(mutex, 1, NULL);
145 }
146 #endif /* _PY_USE_CV_LOCKS */
147
148 unsigned long PyThread_get_thread_ident(void);
149
150 #ifdef PY_HAVE_THREAD_NATIVE_ID
151 unsigned long PyThread_get_thread_native_id(void);
152 #endif
153
154 /*
155 * Initialization for the current runtime.
156 */
157 static void
158 PyThread__init_thread(void)
159 {
160 // Initialization of the C package should not be needed.
161 }
162
163 /*
164 * Thread support.
165 */
166
167 typedef struct {
168 void (*func)(void*);
169 void *arg;
170 } callobj;
171
172 /* thunker to call adapt between the function type used by the system's
173 thread start function and the internally used one. */
174 static unsigned __stdcall
175 bootstrap(void *call)
176 {
177 callobj *obj = (callobj*)call;
178 void (*func)(void*) = obj->func;
179 void *arg = obj->arg;
180 HeapFree(GetProcessHeap(), 0, obj);
181 func(arg);
182 return 0;
183 }
184
185 unsigned long
186 PyThread_start_new_thread(void (*func)(void *), void *arg)
187 {
188 HANDLE hThread;
189 unsigned threadID;
190 callobj *obj;
191
192 if (!initialized)
193 PyThread_init_thread();
194
195 obj = (callobj*)HeapAlloc(GetProcessHeap(), 0, sizeof(*obj));
196 if (!obj)
197 return PYTHREAD_INVALID_THREAD_ID;
198 obj->func = func;
199 obj->arg = arg;
200 PyThreadState *tstate = _PyThreadState_GET();
201 size_t stacksize = tstate ? tstate->interp->threads.stacksize : 0;
202 hThread = (HANDLE)_beginthreadex(0,
203 Py_SAFE_DOWNCAST(stacksize, Py_ssize_t, unsigned int),
204 bootstrap, obj,
205 0, &threadID);
206 if (hThread == 0) {
207 /* I've seen errno == EAGAIN here, which means "there are
208 * too many threads".
209 */
210 int e = errno;
211 threadID = (unsigned)-1;
212 HeapFree(GetProcessHeap(), 0, obj);
213 }
214 else {
215 CloseHandle(hThread);
216 }
217 return threadID;
218 }
219
220 /*
221 * Return the thread Id instead of a handle. The Id is said to uniquely identify the
222 * thread in the system
223 */
224 unsigned long
225 PyThread_get_thread_ident(void)
226 {
227 if (!initialized)
228 PyThread_init_thread();
229
230 return GetCurrentThreadId();
231 }
232
233 #ifdef PY_HAVE_THREAD_NATIVE_ID
234 /*
235 * Return the native Thread ID (TID) of the calling thread.
236 * The native ID of a thread is valid and guaranteed to be unique system-wide
237 * from the time the thread is created until the thread has been terminated.
238 */
239 unsigned long
240 PyThread_get_thread_native_id(void)
241 {
242 if (!initialized) {
243 PyThread_init_thread();
244 }
245
246 DWORD native_id;
247 native_id = GetCurrentThreadId();
248 return (unsigned long) native_id;
249 }
250 #endif
251
252 void _Py_NO_RETURN
253 PyThread_exit_thread(void)
254 {
255 if (!initialized)
256 exit(0);
257 _endthreadex(0);
258 }
259
260 /*
261 * Lock support. It has to be implemented as semaphores.
262 * I [Dag] tried to implement it with mutex but I could find a way to
263 * tell whether a thread already own the lock or not.
264 */
265 PyThread_type_lock
266 PyThread_allocate_lock(void)
267 {
268 PNRMUTEX mutex;
269
270 if (!initialized)
271 PyThread_init_thread();
272
273 mutex = AllocNonRecursiveMutex() ;
274
275 PyThread_type_lock aLock = (PyThread_type_lock) mutex;
276 assert(aLock);
277
278 return aLock;
279 }
280
281 void
282 PyThread_free_lock(PyThread_type_lock aLock)
283 {
284 FreeNonRecursiveMutex(aLock) ;
285 }
286
287 // WaitForSingleObject() accepts timeout in milliseconds in the range
288 // [0; 0xFFFFFFFE] (DWORD type). INFINITE value (0xFFFFFFFF) means no
289 // timeout. 0xFFFFFFFE milliseconds is around 49.7 days.
290 const DWORD TIMEOUT_MS_MAX = 0xFFFFFFFE;
291
292 /*
293 * Return 1 on success if the lock was acquired
294 *
295 * and 0 if the lock was not acquired. This means a 0 is returned
296 * if the lock has already been acquired by this thread!
297 */
298 PyLockStatus
299 PyThread_acquire_lock_timed(PyThread_type_lock aLock,
300 PY_TIMEOUT_T microseconds, int intr_flag)
301 {
302 assert(aLock);
303
304 /* Fow now, intr_flag does nothing on Windows, and lock acquires are
305 * uninterruptible. */
306 PyLockStatus success;
307 PY_TIMEOUT_T milliseconds;
308
309 if (microseconds >= 0) {
310 milliseconds = microseconds / 1000;
311 // Round milliseconds away from zero
312 if (microseconds % 1000 > 0) {
313 milliseconds++;
314 }
315 if (milliseconds > (PY_TIMEOUT_T)TIMEOUT_MS_MAX) {
316 // bpo-41710: PyThread_acquire_lock_timed() cannot report timeout
317 // overflow to the caller, so clamp the timeout to
318 // [0, TIMEOUT_MS_MAX] milliseconds.
319 //
320 // _thread.Lock.acquire() and _thread.RLock.acquire() raise an
321 // OverflowError if microseconds is greater than PY_TIMEOUT_MAX.
322 milliseconds = TIMEOUT_MS_MAX;
323 }
324 assert(milliseconds != INFINITE);
325 }
326 else {
327 milliseconds = INFINITE;
328 }
329
330 if (EnterNonRecursiveMutex((PNRMUTEX)aLock,
331 (DWORD)milliseconds) == WAIT_OBJECT_0) {
332 success = PY_LOCK_ACQUIRED;
333 }
334 else {
335 success = PY_LOCK_FAILURE;
336 }
337
338 return success;
339 }
340 int
341 PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)
342 {
343 return PyThread_acquire_lock_timed(aLock, waitflag ? -1 : 0, 0);
344 }
345
346 void
347 PyThread_release_lock(PyThread_type_lock aLock)
348 {
349 assert(aLock);
350 (void)LeaveNonRecursiveMutex((PNRMUTEX) aLock);
351 }
352
353 /* minimum/maximum thread stack sizes supported */
354 #define THREAD_MIN_STACKSIZE 0x8000 /* 32 KiB */
355 #define THREAD_MAX_STACKSIZE 0x10000000 /* 256 MiB */
356
357 /* set the thread stack size.
358 * Return 0 if size is valid, -1 otherwise.
359 */
360 static int
361 _pythread_nt_set_stacksize(size_t size)
362 {
363 /* set to default */
364 if (size == 0) {
365 _PyInterpreterState_GET()->threads.stacksize = 0;
366 return 0;
367 }
368
369 /* valid range? */
370 if (size >= THREAD_MIN_STACKSIZE && size < THREAD_MAX_STACKSIZE) {
371 _PyInterpreterState_GET()->threads.stacksize = size;
372 return 0;
373 }
374
375 return -1;
376 }
377
378 #define THREAD_SET_STACKSIZE(x) _pythread_nt_set_stacksize(x)
379
380
381 /* Thread Local Storage (TLS) API
382
383 This API is DEPRECATED since Python 3.7. See PEP 539 for details.
384 */
385
386 int
387 PyThread_create_key(void)
388 {
389 DWORD result = TlsAlloc();
390 if (result == TLS_OUT_OF_INDEXES)
391 return -1;
392 return (int)result;
393 }
394
395 void
396 PyThread_delete_key(int key)
397 {
398 TlsFree(key);
399 }
400
401 int
402 PyThread_set_key_value(int key, void *value)
403 {
404 BOOL ok = TlsSetValue(key, value);
405 return ok ? 0 : -1;
406 }
407
408 void *
409 PyThread_get_key_value(int key)
410 {
411 /* because TLS is used in the Py_END_ALLOW_THREAD macro,
412 * it is necessary to preserve the windows error state, because
413 * it is assumed to be preserved across the call to the macro.
414 * Ideally, the macro should be fixed, but it is simpler to
415 * do it here.
416 */
417 DWORD error = GetLastError();
418 void *result = TlsGetValue(key);
419 SetLastError(error);
420 return result;
421 }
422
423 void
424 PyThread_delete_key_value(int key)
425 {
426 /* NULL is used as "key missing", and it is also the default
427 * given by TlsGetValue() if nothing has been set yet.
428 */
429 TlsSetValue(key, NULL);
430 }
431
432
433 /* reinitialization of TLS is not necessary after fork when using
434 * the native TLS functions. And forking isn't supported on Windows either.
435 */
436 void
437 PyThread_ReInitTLS(void)
438 {
439 }
440
441
442 /* Thread Specific Storage (TSS) API
443
444 Platform-specific components of TSS API implementation.
445 */
446
447 int
448 PyThread_tss_create(Py_tss_t *key)
449 {
450 assert(key != NULL);
451 /* If the key has been created, function is silently skipped. */
452 if (key->_is_initialized) {
453 return 0;
454 }
455
456 DWORD result = TlsAlloc();
457 if (result == TLS_OUT_OF_INDEXES) {
458 return -1;
459 }
460 /* In Windows, platform-specific key type is DWORD. */
461 key->_key = result;
462 key->_is_initialized = 1;
463 return 0;
464 }
465
466 void
467 PyThread_tss_delete(Py_tss_t *key)
468 {
469 assert(key != NULL);
470 /* If the key has not been created, function is silently skipped. */
471 if (!key->_is_initialized) {
472 return;
473 }
474
475 TlsFree(key->_key);
476 key->_key = TLS_OUT_OF_INDEXES;
477 key->_is_initialized = 0;
478 }
479
480 int
481 PyThread_tss_set(Py_tss_t *key, void *value)
482 {
483 assert(key != NULL);
484 BOOL ok = TlsSetValue(key->_key, value);
485 return ok ? 0 : -1;
486 }
487
488 void *
489 PyThread_tss_get(Py_tss_t *key)
490 {
491 assert(key != NULL);
492 /* because TSS is used in the Py_END_ALLOW_THREAD macro,
493 * it is necessary to preserve the windows error state, because
494 * it is assumed to be preserved across the call to the macro.
495 * Ideally, the macro should be fixed, but it is simpler to
496 * do it here.
497 */
498 DWORD error = GetLastError();
499 void *result = TlsGetValue(key->_key);
500 SetLastError(error);
501 return result;
502 }