summaryrefslogtreecommitdiff
path: root/src/systhread.c
blob: c68853cacac9dd477355bb695fb20f8969edb38a (plain)
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
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
/* System thread definitions
Copyright (C) 2012-2021 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>
#include <setjmp.h>
#include <stdio.h>
#include <string.h>
#include "lisp.h"

#ifdef HAVE_NS
#include "nsterm.h"
#endif

#ifdef HAVE_PTHREAD_SET_NAME_NP
#include <pthread_np.h>
#endif

#ifndef THREADS_ENABLED

void
sys_mutex_init (sys_mutex_t *m)
{
  *m = 0;
}

void
sys_mutex_lock (sys_mutex_t *m)
{
}

void
sys_mutex_unlock (sys_mutex_t *m)
{
}

void
sys_cond_init (sys_cond_t *c)
{
  *c = 0;
}

void
sys_cond_wait (sys_cond_t *c, sys_mutex_t *m)
{
}

void
sys_cond_signal (sys_cond_t *c)
{
}

void
sys_cond_broadcast (sys_cond_t *c)
{
}

void
sys_cond_destroy (sys_cond_t *c)
{
}

sys_thread_t
sys_thread_self (void)
{
  return 0;
}

bool
sys_thread_equal (sys_thread_t t, sys_thread_t u)
{
  return t == u;
}
void
sys_thread_set_name (const char *name)
{
}

bool
sys_thread_create (sys_thread_t *t, thread_creation_function *func, void *datum)
{
  return false;
}

void
sys_thread_yield (void)
{
}

#elif defined (HAVE_PTHREAD)

#include <sched.h>

void
sys_mutex_init (sys_mutex_t *mutex)
{
  pthread_mutexattr_t *attr_ptr;
#ifdef ENABLE_CHECKING
  pthread_mutexattr_t attr;
  {
    int error = pthread_mutexattr_init (&attr);
    eassert (error == 0);
    error = pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ERRORCHECK);
    eassert (error == 0);
  }
  attr_ptr = &attr;
#else
  attr_ptr = NULL;
#endif
  int error = pthread_mutex_init (mutex, attr_ptr);
  /* We could get ENOMEM.  Can't do anything except aborting.  */
  if (error != 0)
    {
      fprintf (stderr, "\npthread_mutex_init failed: %s\n", strerror (error));
      emacs_abort ();
    }
#ifdef ENABLE_CHECKING
  error = pthread_mutexattr_destroy (&attr);
  eassert (error == 0);
#endif
}

void
sys_mutex_lock (sys_mutex_t *mutex)
{
  int error = pthread_mutex_lock (mutex);
  eassert (error == 0);
}

void
sys_mutex_unlock (sys_mutex_t *mutex)
{
  int error = pthread_mutex_unlock (mutex);
  eassert (error == 0);
}

void
sys_cond_init (sys_cond_t *cond)
{
  int error = pthread_cond_init (cond, NULL);
  /* We could get ENOMEM.  Can't do anything except aborting.  */
  if (error != 0)
    {
      fprintf (stderr, "\npthread_cond_init failed: %s\n", strerror (error));
      emacs_abort ();
    }
}

void
sys_cond_wait (sys_cond_t *cond, sys_mutex_t *mutex)
{
  int error = pthread_cond_wait (cond, mutex);
  eassert (error == 0);
}

void
sys_cond_signal (sys_cond_t *cond)
{
  int error = pthread_cond_signal (cond);
  eassert (error == 0);
}

void
sys_cond_broadcast (sys_cond_t *cond)
{
  int error = pthread_cond_broadcast (cond);
  eassert (error == 0);
#ifdef HAVE_NS
  /* Send an app defined event to break out of the NS run loop.
     It seems that if ns_select is running the NS run loop, this
     broadcast has no effect until the loop is done, breaking a couple
     of tests in thread-tests.el. */
  ns_run_loop_break ();
#endif
}

void
sys_cond_destroy (sys_cond_t *cond)
{
  int error = pthread_cond_destroy (cond);
  eassert (error == 0);
}

sys_thread_t
sys_thread_self (void)
{
  return pthread_self ();
}

bool
sys_thread_equal (sys_thread_t t, sys_thread_t u)
{
  return pthread_equal (t, u);
}

void
sys_thread_set_name (const char *name)
{
#ifdef HAVE_PTHREAD_SETNAME_NP
  /* We need to truncate here otherwise pthread_setname_np
     fails to set the name.  TASK_COMM_LEN is what the length
     is called in the Linux kernel headers (Bug#38632).  */
#define TASK_COMM_LEN 16
  char p_name[TASK_COMM_LEN];
  strncpy (p_name, name, TASK_COMM_LEN - 1);
  p_name[TASK_COMM_LEN - 1] = '\0';
# ifdef HAVE_PTHREAD_SETNAME_NP_1ARG
  pthread_setname_np (p_name);
# elif defined HAVE_PTHREAD_SETNAME_NP_3ARG
  pthread_setname_np (pthread_self (), "%s", p_name);
# else
  pthread_setname_np (pthread_self (), p_name);
# endif
#elif HAVE_PTHREAD_SET_NAME_NP
  /* The name will automatically be truncated if it exceeds a
     system-specific length.  */
  pthread_set_name_np (pthread_self (), name);
#endif
}

bool
sys_thread_create (sys_thread_t *thread_ptr, thread_creation_function *func,
                   void *arg)
{
  pthread_attr_t attr;
  bool result = false;

  if (pthread_attr_init (&attr))
    return false;

  /* Avoid crash on macOS with deeply nested GC (Bug#30364).  */
  size_t stack_size;
  size_t required_stack_size = sizeof (void *) * 1024 * 1024;
  if (pthread_attr_getstacksize (&attr, &stack_size) == 0
      && stack_size < required_stack_size)
    {
      if (pthread_attr_setstacksize (&attr, required_stack_size) != 0)
        goto out;
    }

  if (!pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED))
    result = pthread_create (thread_ptr, &attr, func, arg) == 0;

 out: ;
  int error = pthread_attr_destroy (&attr);
  eassert (error == 0);

  return result;
}

void
sys_thread_yield (void)
{
  sched_yield ();
}

#elif defined (WINDOWSNT)

#include <mbctype.h>
#include "w32term.h"

/* Cannot include <process.h> because of the local header by the same
   name, sigh.  */
uintptr_t _beginthread (void (__cdecl *)(void *), unsigned, void *);

/* Mutexes are implemented as critical sections, because they are
   faster than Windows mutex objects (implemented in userspace), and
   satisfy the requirements, since we only need to synchronize within a
   single process.  */
void
sys_mutex_init (sys_mutex_t *mutex)
{
  InitializeCriticalSection ((LPCRITICAL_SECTION)mutex);
}

void
sys_mutex_lock (sys_mutex_t *mutex)
{
  /* FIXME: What happens if the owning thread exits without releasing
     the mutex?  According to MSDN, the result is undefined behavior.  */
  EnterCriticalSection ((LPCRITICAL_SECTION)mutex);
}

void
sys_mutex_unlock (sys_mutex_t *mutex)
{
  LeaveCriticalSection ((LPCRITICAL_SECTION)mutex);
}

void
sys_cond_init (sys_cond_t *cond)
{
  cond->initialized = false;
  cond->wait_count = 0;
  /* Auto-reset event for signal.  */
  cond->events[CONDV_SIGNAL] = CreateEvent (NULL, FALSE, FALSE, NULL);
  /* Manual-reset event for broadcast.  */
  cond->events[CONDV_BROADCAST] = CreateEvent (NULL, TRUE, FALSE, NULL);
  if (!cond->events[CONDV_SIGNAL] || !cond->events[CONDV_BROADCAST])
    return;
  InitializeCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);
  cond->initialized = true;
}

void
sys_cond_wait (sys_cond_t *cond, sys_mutex_t *mutex)
{
  DWORD wait_result;
  bool last_thread_waiting;

  if (!cond->initialized)
    return;

  /* Increment the wait count avoiding race conditions.  */
  EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);
  cond->wait_count++;
  LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);

  /* Release the mutex and wait for either the signal or the broadcast
     event.  */
  LeaveCriticalSection ((LPCRITICAL_SECTION)mutex);
  wait_result = WaitForMultipleObjects (2, cond->events, FALSE, INFINITE);

  /* Decrement the wait count and see if we are the last thread
     waiting on the condition variable.  */
  EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);
  cond->wait_count--;
  last_thread_waiting =
    wait_result == WAIT_OBJECT_0 + CONDV_BROADCAST
    && cond->wait_count == 0;
  LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);

  /* Broadcast uses a manual-reset event, so when the last thread is
     released, we must manually reset that event.  */
  if (last_thread_waiting)
    ResetEvent (cond->events[CONDV_BROADCAST]);

  /* Per the API, re-acquire the mutex.  */
  EnterCriticalSection ((LPCRITICAL_SECTION)mutex);
}

void
sys_cond_signal (sys_cond_t *cond)
{
  bool threads_waiting;

  if (!cond->initialized)
    return;

  EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);
  threads_waiting = cond->wait_count > 0;
  LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);

  if (threads_waiting)
    SetEvent (cond->events[CONDV_SIGNAL]);
}

void
sys_cond_broadcast (sys_cond_t *cond)
{
  bool threads_waiting;

  if (!cond->initialized)
    return;

  EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);
  threads_waiting = cond->wait_count > 0;
  LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);

  if (threads_waiting)
    SetEvent (cond->events[CONDV_BROADCAST]);
}

void
sys_cond_destroy (sys_cond_t *cond)
{
  if (cond->events[CONDV_SIGNAL])
    CloseHandle (cond->events[CONDV_SIGNAL]);
  if (cond->events[CONDV_BROADCAST])
    CloseHandle (cond->events[CONDV_BROADCAST]);

  if (!cond->initialized)
    return;

  /* FIXME: What if wait_count is non-zero, i.e. there are still
     threads waiting on this condition variable?  */
  DeleteCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock);
}

sys_thread_t
sys_thread_self (void)
{
  return (sys_thread_t) GetCurrentThreadId ();
}

bool
sys_thread_equal (sys_thread_t t, sys_thread_t u)
{
  return t == u;
}

/* Special exception used to communicate with a debugger.  The name is
   taken from example code shown on MSDN.  */
#define MS_VC_EXCEPTION 0x406d1388UL

/* Structure used to communicate thread name to a debugger.  */
typedef struct _THREADNAME_INFO
{
  DWORD_PTR  type;
  LPCSTR name;
  DWORD_PTR  thread_id;
  DWORD_PTR  reserved;
} THREADNAME_INFO;

typedef BOOL (WINAPI *IsDebuggerPresent_Proc) (void);
extern IsDebuggerPresent_Proc is_debugger_present;
extern int (WINAPI *pMultiByteToWideChar)(UINT,DWORD,LPCSTR,int,LPWSTR,int);
typedef HRESULT (WINAPI *SetThreadDescription_Proc)
  (HANDLE hThread, PCWSTR lpThreadDescription);
extern SetThreadDescription_Proc set_thread_description;

/* Set the name of the thread identified by its thread ID.  */
static void
w32_set_thread_name (DWORD thread_id, const char *name)
{
  if (!name || !*name)
    return;

  /* Use the new API provided since Windows 10, if available.  */
  if (set_thread_description)
    {
      /* GDB pulls only the first 1024 characters of thread's name.  */
      wchar_t name_w[1025];
      /* The thread name is encoded in locale's encoding, but
	 SetThreadDescription wants a wchar_t string.  */
      int codepage = _getmbcp ();
      if (!codepage)
	codepage = GetACP ();
      int cnv_result = pMultiByteToWideChar (codepage, MB_ERR_INVALID_CHARS,
					     name, -1,
					     name_w, 1025);
      if (cnv_result
	  && set_thread_description (GetCurrentThread (), name_w) == S_OK)
	return;
    }
  /* We can only support this fallback method when Emacs is being
     debugged.  */
  if (!(is_debugger_present && is_debugger_present ()))
    return;

  THREADNAME_INFO tninfo;

  tninfo.type = 0x1000;	/* magic constant */
  tninfo.name = name;
  tninfo.thread_id = thread_id;
  tninfo.reserved = 0;
  RaiseException (MS_VC_EXCEPTION, 0, sizeof (tninfo) / sizeof (ULONG_PTR),
		  (ULONG_PTR *) &tninfo);
}

static thread_creation_function *thread_start_address;

void
sys_thread_set_name (const char *name)
{
  w32_set_thread_name (GetCurrentThreadId (), name);
}

/* _beginthread wants a void function, while we are passed a function
   that returns a pointer.  So we use a wrapper.  See the command in
   w32term.h about the need for ALIGN_STACK attribute.  */
static void ALIGN_STACK
w32_beginthread_wrapper (void *arg)
{
  (void)thread_start_address (arg);
}

bool
sys_thread_create (sys_thread_t *thread_ptr, thread_creation_function *func,
                   void *arg)
{
  /* FIXME: Do threads that run Lisp require some minimum amount of
     stack?  Zero here means each thread will get the same amount as
     the main program.  On GNU/Linux, it seems like the stack is 2MB
     by default, overridden by RLIMIT_STACK at program start time.
     Not sure what to do with this.  See also the comment in
     w32proc.c:new_child.  */
  const unsigned stack_size = 0;
  uintptr_t thandle;

  thread_start_address = func;

  /* We use _beginthread rather than CreateThread because the former
     arranges for the thread handle to be automatically closed when
     the thread exits, thus preventing handle leaks and/or the need to
     track all the threads and close their handles when they exit.
     Also, MSDN seems to imply that code which uses CRT _must_ call
     _beginthread, although if that is true, we already violate that
     rule in many places...  */
  thandle = _beginthread (w32_beginthread_wrapper, stack_size, arg);
  if (thandle == (uintptr_t)-1L)
    return false;

  /* Kludge alert!  We use the Windows thread ID, an unsigned 32-bit
     number, as the sys_thread_t type, because that ID is the only
     unique identifier of a thread on Windows.  But _beginthread
     returns a handle of the thread, and there's no easy way of
     getting the thread ID given a handle (GetThreadId is available
     only since Vista, so we cannot use it portably).  Fortunately,
     the value returned by sys_thread_create is not used by its
     callers; instead, run_thread, which runs in the context of the
     new thread, calls sys_thread_self and uses its return value;
     sys_thread_self in this implementation calls GetCurrentThreadId.
     Therefore, we return some more or less arbitrary value of the
     thread ID from this function. */
  *thread_ptr = thandle & 0xFFFFFFFF;
  return true;
}

void
sys_thread_yield (void)
{
  Sleep (0);
}

#else

#error port me

#endif