This repository was archived by the owner on Feb 13, 2025. It is now read-only.
forked from python/cpython
-
Notifications
You must be signed in to change notification settings - Fork 64
Expand file tree
/
Copy paththread.c
More file actions
453 lines (390 loc) · 12.6 KB
/
thread.c
File metadata and controls
453 lines (390 loc) · 12.6 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
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
/* Thread package.
This is intended to be usable independently from Python.
The implementation for system foobar is in a file thread_foobar.h
which is included by this file dependent on config settings.
Stuff shared by all thread_*.h files is collected here. */
#include "Python.h"
#ifndef _POSIX_THREADS
/* This means pthreads are not implemented in libc headers, hence the macro
not present in unistd.h. But they still can be implemented as an external
library (e.g. gnu pth in pthread emulation) */
# ifdef HAVE_PTHREAD_H
# include <pthread.h> /* _POSIX_THREADS */
# endif
#endif
#ifndef DONT_HAVE_STDIO_H
#include <stdio.h>
#endif
#include <stdlib.h>
#include "pythread.h"
#ifndef _POSIX_THREADS
/* Check if we're running on HP-UX and _SC_THREADS is defined. If so, then
enough of the Posix threads package is implemented to support python
threads.
This is valid for HP-UX 11.23 running on an ia64 system. If needed, add
a check of __ia64 to verify that we're running on a ia64 system instead
of a pa-risc system.
*/
#ifdef __hpux
#ifdef _SC_THREADS
#define _POSIX_THREADS
#endif
#endif
#endif /* _POSIX_THREADS */
#ifdef Py_DEBUG
static int thread_debug = 0;
#define dprintf(args) (void)((thread_debug & 1) && printf args)
#define d2printf(args) ((thread_debug & 8) && printf args)
#else
#define dprintf(args)
#define d2printf(args)
#endif
static int initialized;
static void PyThread__init_thread(void); /* Forward */
void
PyThread_init_thread(void)
{
#ifdef Py_DEBUG
char *p = Py_GETENV("PYTHONTHREADDEBUG");
if (p) {
if (*p)
thread_debug = atoi(p);
else
thread_debug = 1;
}
#endif /* Py_DEBUG */
if (initialized)
return;
initialized = 1;
dprintf(("PyThread_init_thread called\n"));
PyThread__init_thread();
}
/* Support for runtime thread stack size tuning.
A value of 0 means using the platform's default stack size
or the size specified by the THREAD_STACK_SIZE macro. */
static size_t _pythread_stacksize = 0;
#ifdef _POSIX_THREADS
#define PYTHREAD_NAME "pthread"
#include "thread_pthread.h"
#endif
#ifdef NT_THREADS
#define PYTHREAD_NAME "nt"
#include "thread_nt.h"
#endif
#ifdef OS2_THREADS
#define PYTHREAD_NAME "os2"
#include "thread_os2.h"
#endif
/*
#ifdef FOOBAR_THREADS
#include "thread_foobar.h"
#endif
*/
/* return the current thread stack size */
size_t
PyThread_get_stacksize(void)
{
return _pythread_stacksize;
}
/* Only platforms defining a THREAD_SET_STACKSIZE() macro
in thread_<platform>.h support changing the stack size.
Return 0 if stack size is valid,
-1 if stack size value is invalid,
-2 if setting stack size is not supported. */
int
PyThread_set_stacksize(size_t size)
{
#if defined(THREAD_SET_STACKSIZE)
return THREAD_SET_STACKSIZE(size);
#else
return -2;
#endif
}
#ifndef Py_HAVE_NATIVE_TLS
/* If the platform has not supplied a platform specific
TLS implementation, provide our own.
This code stolen from "thread_sgi.h", where it was the only
implementation of an existing Python TLS API.
*/
/* ------------------------------------------------------------------------
Per-thread data ("key") support.
Use PyThread_create_key() to create a new key. This is typically shared
across threads.
Use PyThread_set_key_value(thekey, value) to associate void* value with
thekey in the current thread. Each thread has a distinct mapping of thekey
to a void* value. Caution: if the current thread already has a mapping
for thekey, value is ignored.
Use PyThread_get_key_value(thekey) to retrieve the void* value associated
with thekey in the current thread. This returns NULL if no value is
associated with thekey in the current thread.
Use PyThread_delete_key_value(thekey) to forget the current thread's associated
value for thekey. PyThread_delete_key(thekey) forgets the values associated
with thekey across *all* threads.
While some of these functions have error-return values, none set any
Python exception.
None of the functions does memory management on behalf of the void* values.
You need to allocate and deallocate them yourself. If the void* values
happen to be PyObject*, these functions don't do refcount operations on
them either.
The GIL does not need to be held when calling these functions; they supply
their own locking. This isn't true of PyThread_create_key(), though (see
next paragraph).
There's a hidden assumption that PyThread_create_key() will be called before
any of the other functions are called. There's also a hidden assumption
that calls to PyThread_create_key() are serialized externally.
------------------------------------------------------------------------ */
/* A singly-linked list of struct key objects remembers all the key->value
* associations. File static keyhead heads the list. keymutex is used
* to enforce exclusion internally.
*/
struct key {
/* Next record in the list, or NULL if this is the last record. */
struct key *next;
/* The thread id, according to PyThread_get_thread_ident(). */
long id;
/* The key and its associated value. */
int key;
void *value;
};
static struct key *keyhead = NULL;
static PyThread_type_lock keymutex = NULL;
static int nkeys = 0; /* PyThread_create_key() hands out nkeys+1 next */
/* Internal helper.
* If the current thread has a mapping for key, the appropriate struct key*
* is returned. NB: value is ignored in this case!
* If there is no mapping for key in the current thread, then:
* If value is NULL, NULL is returned.
* Else a mapping of key to value is created for the current thread,
* and a pointer to a new struct key* is returned; except that if
* malloc() can't find room for a new struct key*, NULL is returned.
* So when value==NULL, this acts like a pure lookup routine, and when
* value!=NULL, this acts like dict.setdefault(), returning an existing
* mapping if one exists, else creating a new mapping.
*
* Caution: this used to be too clever, trying to hold keymutex only
* around the "p->next = keyhead; keyhead = p" pair. That allowed
* another thread to mutate the list, via key deletion, concurrent with
* find_key() crawling over the list. Hilarity ensued. For example, when
* the for-loop here does "p = p->next", p could end up pointing at a
* record that PyThread_delete_key_value() was concurrently free()'ing.
* That could lead to anything, from failing to find a key that exists, to
* segfaults. Now we lock the whole routine.
*/
static struct key *
find_key(int key, void *value)
{
struct key *p, *prev_p;
long id = PyThread_get_thread_ident();
if (!keymutex)
return NULL;
PyThread_acquire_lock(keymutex, 1);
prev_p = NULL;
for (p = keyhead; p != NULL; p = p->next) {
if (p->id == id && p->key == key)
goto Done;
/* Sanity check. These states should never happen but if
* they do we must abort. Otherwise we'll end up spinning in
* in a tight loop with the lock held. A similar check is done
* in pystate.c tstate_delete_common(). */
if (p == prev_p)
Py_FatalError("tls find_key: small circular list(!)");
prev_p = p;
if (p->next == keyhead)
Py_FatalError("tls find_key: circular list(!)");
}
if (value == NULL) {
assert(p == NULL);
goto Done;
}
p = (struct key *)malloc(sizeof(struct key));
if (p != NULL) {
p->id = id;
p->key = key;
p->value = value;
p->next = keyhead;
keyhead = p;
}
Done:
PyThread_release_lock(keymutex);
return p;
}
/* Return a new key. This must be called before any other functions in
* this family, and callers must arrange to serialize calls to this
* function. No violations are detected.
*/
int
PyThread_create_key(void)
{
/* All parts of this function are wrong if it's called by multiple
* threads simultaneously.
*/
if (keymutex == NULL)
keymutex = PyThread_allocate_lock();
return ++nkeys;
}
/* Forget the associations for key across *all* threads. */
void
PyThread_delete_key(int key)
{
struct key *p, **q;
PyThread_acquire_lock(keymutex, 1);
q = &keyhead;
while ((p = *q) != NULL) {
if (p->key == key) {
*q = p->next;
free((void *)p);
/* NB This does *not* free p->value! */
}
else
q = &p->next;
}
PyThread_release_lock(keymutex);
}
/* Confusing: If the current thread has an association for key,
* value is ignored, and 0 is returned. Else an attempt is made to create
* an association of key to value for the current thread. 0 is returned
* if that succeeds, but -1 is returned if there's not enough memory
* to create the association. value must not be NULL.
*/
int
PyThread_set_key_value(int key, void *value)
{
struct key *p;
assert(value != NULL);
p = find_key(key, value);
if (p == NULL)
return -1;
else
return 0;
}
/* Retrieve the value associated with key in the current thread, or NULL
* if the current thread doesn't have an association for key.
*/
void *
PyThread_get_key_value(int key)
{
struct key *p = find_key(key, NULL);
if (p == NULL)
return NULL;
else
return p->value;
}
/* Forget the current thread's association for key, if any. */
void
PyThread_delete_key_value(int key)
{
long id = PyThread_get_thread_ident();
struct key *p, **q;
PyThread_acquire_lock(keymutex, 1);
q = &keyhead;
while ((p = *q) != NULL) {
if (p->key == key && p->id == id) {
*q = p->next;
free((void *)p);
/* NB This does *not* free p->value! */
break;
}
else
q = &p->next;
}
PyThread_release_lock(keymutex);
}
/* Forget everything not associated with the current thread id.
* This function is called from PyOS_AfterFork(). It is necessary
* because other thread ids which were in use at the time of the fork
* may be reused for new threads created in the forked process.
*/
void
PyThread_ReInitTLS(void)
{
long id = PyThread_get_thread_ident();
struct key *p, **q;
if (!keymutex)
return;
/* As with interpreter_lock in PyEval_ReInitThreads()
we just create a new lock without freeing the old one */
keymutex = PyThread_allocate_lock();
/* Delete all keys which do not match the current thread id */
q = &keyhead;
while ((p = *q) != NULL) {
if (p->id != id) {
*q = p->next;
free((void *)p);
/* NB This does *not* free p->value! */
}
else
q = &p->next;
}
}
#endif /* Py_HAVE_NATIVE_TLS */
PyDoc_STRVAR(threadinfo__doc__,
"sys.thread_info\n\
\n\
A struct sequence holding information about the thread implementation.");
static PyStructSequence_Field threadinfo_fields[] = {
{"name", "name of the thread implementation"},
{"lock", "name of the lock implementation"},
{"version", "name and version of the thread library"},
{0}
};
static PyStructSequence_Desc threadinfo_desc = {
"sys.thread_info", /* name */
threadinfo__doc__, /* doc */
threadinfo_fields, /* fields */
3
};
static PyTypeObject ThreadInfoType;
PyObject*
PyThread_GetInfo(void)
{
PyObject *threadinfo, *value;
int pos = 0;
#if (defined(_POSIX_THREADS) && defined(HAVE_CONFSTR) \
&& defined(_CS_GNU_LIBPTHREAD_VERSION))
char buffer[255];
int len;
#endif
if (ThreadInfoType.tp_name == 0)
PyStructSequence_InitType(&ThreadInfoType, &threadinfo_desc);
threadinfo = PyStructSequence_New(&ThreadInfoType);
if (threadinfo == NULL)
return NULL;
value = PyUnicode_FromString(PYTHREAD_NAME);
if (value == NULL) {
Py_DECREF(threadinfo);
return NULL;
}
PyStructSequence_SET_ITEM(threadinfo, pos++, value);
#ifdef _POSIX_THREADS
#ifdef USE_SEMAPHORES
value = PyUnicode_FromString("semaphore");
#else
value = PyUnicode_FromString("mutex+cond");
#endif
if (value == NULL) {
Py_DECREF(threadinfo);
return NULL;
}
#else
Py_INCREF(Py_None);
value = Py_None;
#endif
PyStructSequence_SET_ITEM(threadinfo, pos++, value);
#if (defined(_POSIX_THREADS) && defined(HAVE_CONFSTR) \
&& defined(_CS_GNU_LIBPTHREAD_VERSION))
value = NULL;
len = confstr(_CS_GNU_LIBPTHREAD_VERSION, buffer, sizeof(buffer));
if (1 < len && len < sizeof(buffer)) {
value = PyUnicode_DecodeFSDefaultAndSize(buffer, len-1);
if (value == NULL)
PyErr_Clear();
}
if (value == NULL)
#endif
{
Py_INCREF(Py_None);
value = Py_None;
}
PyStructSequence_SET_ITEM(threadinfo, pos++, value);
return threadinfo;
}