summaryrefslogtreecommitdiffstats
path: root/libjava/win32-threads.cc
blob: f2dbaaf9454aa7001b93f59f68c0bec8584181fd (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
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
// win32-threads.cc - interface between libjava and Win32 threads.

/* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2006 Free Software
   Foundation, Inc.

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

#include <config.h>

// If we're using the Boehm GC, then we need to override some of the
// thread primitives.  This is fairly gross.
#ifdef HAVE_BOEHM_GC
extern "C"
{
#include <gc.h>
// <windows.h> #define's STRICT, which conflicts with Modifier.h
#undef STRICT
};
#endif /* HAVE_BOEHM_GC */

#include <gcj/cni.h>
#include <jvm.h>
#include <java/lang/Thread.h>
#include <java/lang/System.h>

#include <errno.h>

#ifndef ETIMEDOUT
#define ETIMEDOUT 116
#endif

// This is used to implement thread startup.
struct starter
{
  _Jv_ThreadStartFunc *method;
  _Jv_Thread_t *data;
};

// Controls access to the variable below
static HANDLE daemon_mutex;
static HANDLE daemon_cond;
// Number of non-daemon threads - _Jv_ThreadWait returns when this is 0
static int non_daemon_count;

// TLS key get Java object representing the thread
DWORD _Jv_ThreadKey;
// TLS key to get _Jv_Thread_t* representing the thread
DWORD _Jv_ThreadDataKey;

//
// These are the flags that can appear in _Jv_Thread_t.
//

// Thread started.
#define FLAG_START   0x01
// Thread is daemon.
#define FLAG_DAEMON  0x02

//
// Helper
//
inline bool
compare_and_exchange(LONG volatile* dest, LONG cmp, LONG xchg)
{
  return InterlockedCompareExchange((LONG*) dest, xchg, cmp) == cmp;
    // Seems like a bug in the MinGW headers that we have to do this cast.
}

//
// Condition variables.
//

// we do lazy creation of Events since CreateEvent() is insanely
// expensive, and because the rest of libgcj will call _Jv_CondInit
// when only a mutex is needed.

inline void
ensure_condvar_initialized(_Jv_ConditionVariable_t *cv)
{
  if (cv->ev[0] == 0)
    {
      cv->ev[0] = CreateEvent (NULL, 0, 0, NULL);
      if (cv->ev[0] == 0) JvFail("CreateEvent() failed");

      cv->ev[1] = CreateEvent (NULL, 1, 0, NULL);
      if (cv->ev[1] == 0) JvFail("CreateEvent() failed");
    }
}

inline void
ensure_interrupt_event_initialized(HANDLE& rhEvent)
{
  if (!rhEvent)
    {
      rhEvent = CreateEvent (NULL, 0, 0, NULL);
      if (!rhEvent) JvFail("CreateEvent() failed");
    }
}

// Reimplementation of the general algorithm described at
// http://www.cs.wustl.edu/~schmidt/win32-cv-1.html (isomorphic to
// 3.2, not a cut-and-paste).

int
_Jv_CondWait(_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu, jlong millis, jint nanos)
{
  if (mu->owner != GetCurrentThreadId ( ))
    return _JV_NOT_OWNER;

  _Jv_Thread_t *current = _Jv_ThreadCurrentData ();
  java::lang::Thread *current_obj = _Jv_ThreadCurrent ();

  // Now that we hold the interrupt mutex, check if this thread has been 
  // interrupted already.
  EnterCriticalSection (&current->interrupt_mutex);
  ensure_interrupt_event_initialized (current->interrupt_event);
  jboolean interrupted = current_obj->interrupt_flag;
  LeaveCriticalSection (&current->interrupt_mutex);

  if (interrupted)
    {
      return _JV_INTERRUPTED;
    }

  EnterCriticalSection (&cv->count_mutex);
  ensure_condvar_initialized (cv);
  cv->blocked_count++;
  LeaveCriticalSection (&cv->count_mutex);

  DWORD time;
  if ((millis == 0) && (nanos > 0)) time = 1;
  else if (millis == 0) time = INFINITE;
  else time = millis;

  // Record the current lock depth, so it can be restored
  // when we reacquire it.
  int count = mu->refcount;
  int curcount = count;

  // Call _Jv_MutexUnlock repeatedly until this thread
  // has completely released the monitor.
  while (curcount > 0)
    {  
      _Jv_MutexUnlock (mu);
      --curcount;
    }

  // Set up our array of three events:
  // - the auto-reset event (for notify())
  // - the manual-reset event (for notifyAll())
  // - the interrupt event (for interrupt())
  // We wait for any one of these to be signaled.
  HANDLE arh[3];
  arh[0] = cv->ev[0];
  arh[1] = cv->ev[1];
  arh[2] = current->interrupt_event;
  DWORD rval = WaitForMultipleObjects (3, arh, 0, time);

  EnterCriticalSection (&current->interrupt_mutex);

  // If we were unblocked by the third event (our thread's interrupt
  // event), set the thread's interrupt flag. I think this sanity
  // check guards against someone resetting our interrupt flag
  // in the time between when interrupt_mutex is released in
  // _Jv_ThreadInterrupt and the interval of time between the
  // WaitForMultipleObjects call we just made and our acquisition
  // of interrupt_mutex.
  if (rval == (WAIT_OBJECT_0 + 2))
    current_obj->interrupt_flag = true;
    
  interrupted = current_obj->interrupt_flag;
  LeaveCriticalSection (&current->interrupt_mutex);

  EnterCriticalSection(&cv->count_mutex);
  cv->blocked_count--;
  // If we were unblocked by the second event (the broadcast one)
  // and nobody is left, then reset the event.
  int last_waiter = (rval == (WAIT_OBJECT_0 + 1)) && (cv->blocked_count == 0);
  LeaveCriticalSection(&cv->count_mutex);

  if (last_waiter)
    ResetEvent (cv->ev[1]);

  // Call _Jv_MutexLock repeatedly until the mutex's refcount is the
  // same as before we originally released it.
  while (curcount < count)
    {  
      _Jv_MutexLock (mu);
      ++curcount;
    }
  
  return interrupted ? _JV_INTERRUPTED : 0;
}

void
_Jv_CondInit (_Jv_ConditionVariable_t *cv)
{
  // we do lazy creation of Events since CreateEvent() is insanely expensive
  cv->ev[0] = 0;
  InitializeCriticalSection (&cv->count_mutex);
  cv->blocked_count = 0;
}

void
_Jv_CondDestroy (_Jv_ConditionVariable_t *cv)
{
  if (cv->ev[0] != 0)
    {
      CloseHandle (cv->ev[0]);
      CloseHandle (cv->ev[1]);

      cv->ev[0] = 0;
    }

  DeleteCriticalSection (&cv->count_mutex);
}

int
_Jv_CondNotify (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu)
{
  if (mu->owner != GetCurrentThreadId ( ))
    return _JV_NOT_OWNER;

  EnterCriticalSection (&cv->count_mutex);
  ensure_condvar_initialized (cv);
  int somebody_is_blocked = cv->blocked_count > 0;
  LeaveCriticalSection (&cv->count_mutex);

  if (somebody_is_blocked)
    SetEvent (cv->ev[0]);

  return 0;
}

int
_Jv_CondNotifyAll (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu)
{
  if (mu->owner != GetCurrentThreadId ( ))
    return _JV_NOT_OWNER;

  EnterCriticalSection (&cv->count_mutex);
  ensure_condvar_initialized (cv);
  int somebody_is_blocked = cv->blocked_count > 0;
  LeaveCriticalSection (&cv->count_mutex);

  if (somebody_is_blocked)
    SetEvent (cv->ev[1]);

  return 0;
}

//
// Threads.
//

void
_Jv_InitThreads (void)
{
  _Jv_ThreadKey = TlsAlloc();
  _Jv_ThreadDataKey = TlsAlloc();
  daemon_mutex = CreateMutex (NULL, 0, NULL);
  daemon_cond = CreateEvent (NULL, 1, 0, NULL);
  non_daemon_count = 0;
}

_Jv_Thread_t *
_Jv_ThreadInitData (java::lang::Thread* obj)
{
  _Jv_Thread_t *data = (_Jv_Thread_t*)_Jv_Malloc(sizeof(_Jv_Thread_t));
  data->flags = 0;
  data->handle = 0;
  data->thread_obj = obj;
  data->interrupt_event = 0;
  InitializeCriticalSection (&data->interrupt_mutex);

  return data;
}

void
_Jv_ThreadDestroyData (_Jv_Thread_t *data)
{
  DeleteCriticalSection (&data->interrupt_mutex);
  if (data->interrupt_event)
    CloseHandle(data->interrupt_event);
  CloseHandle(data->handle);
  _Jv_Free(data);
}

void
_Jv_ThreadSetPriority (_Jv_Thread_t *data, jint prio)
{
  int actual = THREAD_PRIORITY_NORMAL;

  if (data->flags & FLAG_START)
    {
      switch (prio)
        {
          case 10:
            actual = THREAD_PRIORITY_TIME_CRITICAL;
            break;
          case 9:
            actual = THREAD_PRIORITY_HIGHEST;
            break;
          case 8:
          case 7:
            actual = THREAD_PRIORITY_ABOVE_NORMAL;
            break;
          case 6:
          case 5:
            actual = THREAD_PRIORITY_NORMAL;
            break;
          case 4:
          case 3:
            actual = THREAD_PRIORITY_BELOW_NORMAL;
            break;
          case 2:
            actual = THREAD_PRIORITY_LOWEST;
            break;
          case 1:
            actual = THREAD_PRIORITY_IDLE;
            break;
        }
      SetThreadPriority(data->handle, actual);
    }
}

void
_Jv_ThreadRegister (_Jv_Thread_t *data)
{
  TlsSetValue (_Jv_ThreadKey, data->thread_obj);
  TlsSetValue (_Jv_ThreadDataKey, data);
}

void
_Jv_ThreadUnRegister ()
{
  TlsSetValue (_Jv_ThreadKey, NULL);
  TlsSetValue (_Jv_ThreadDataKey, NULL);
}

// This function is called when a thread is started.  We don't arrange
// to call the `run' method directly, because this function must
// return a value.
static DWORD WINAPI
really_start (void* x)
{
  struct starter *info = (struct starter *) x;

  _Jv_ThreadRegister (info->data);

  info->method (info->data->thread_obj);

  if (! (info->data->flags & FLAG_DAEMON))
    {
      WaitForSingleObject (daemon_mutex, INFINITE);
      non_daemon_count--;
      if (! non_daemon_count)
        SetEvent (daemon_cond);
      ReleaseMutex (daemon_mutex);
    }

  return 0;
}

void
_Jv_ThreadStart (java::lang::Thread *thread, _Jv_Thread_t *data, _Jv_ThreadStartFunc *meth)
{
  DWORD id;
  struct starter *info;

  // Do nothing if thread has already started
  if (data->flags & FLAG_START)
    return;
  data->flags |= FLAG_START;

  info = (struct starter *) _Jv_AllocBytes (sizeof (struct starter));
  info->method = meth;
  info->data = data;

  if (! thread->isDaemon ())
    {
      WaitForSingleObject (daemon_mutex, INFINITE);
      non_daemon_count++;
      ReleaseMutex (daemon_mutex);
    }
  else
    data->flags |= FLAG_DAEMON;

  data->handle = GC_CreateThread(NULL, 0, really_start, info, 0, &id);
  _Jv_ThreadSetPriority(data, thread->getPriority());
}

void
_Jv_ThreadWait (void)
{
  WaitForSingleObject (daemon_mutex, INFINITE);
  if (non_daemon_count)
    {
      ReleaseMutex (daemon_mutex);
      WaitForSingleObject (daemon_cond, INFINITE);
    }
}

//
// Interrupt support
//

HANDLE
_Jv_Win32GetInterruptEvent (void)
{
  _Jv_Thread_t *current = _Jv_ThreadCurrentData ();
  EnterCriticalSection (&current->interrupt_mutex);
  ensure_interrupt_event_initialized (current->interrupt_event);
  HANDLE hEvent = current->interrupt_event;
  LeaveCriticalSection (&current->interrupt_mutex);
  return hEvent;
}

void
_Jv_ThreadInterrupt (_Jv_Thread_t *data)
{
  EnterCriticalSection (&data->interrupt_mutex);
  ensure_interrupt_event_initialized (data->interrupt_event);
  data->thread_obj->interrupt_flag = true;
  SetEvent (data->interrupt_event);
  LeaveCriticalSection (&data->interrupt_mutex);
}

// park() / unpark() support

void
ParkHelper::init ()
{
  // We initialize our critical section, but not our event.
  InitializeCriticalSection (&cs);
  event = NULL;
}

void
ParkHelper::init_event()
{
  EnterCriticalSection (&cs);
  if (!event)
    {
      // Create an auto-reset event.
      event = CreateEvent(NULL, 0, 0, NULL);
      if (!event) JvFail("CreateEvent() failed");
    }
  LeaveCriticalSection (&cs);
}

void
ParkHelper::deactivate ()
{
  permit = ::java::lang::Thread::THREAD_PARK_DEAD;
}

void
ParkHelper::destroy()
{
  if (event) CloseHandle (event);
  DeleteCriticalSection (&cs);
}

/**
 * Releases the block on a thread created by _Jv_ThreadPark().  This
 * method can also be used to terminate a blockage caused by a prior
 * call to park.  This operation is unsafe, as the thread must be
 * guaranteed to be live.
 *
 * @param thread the thread to unblock.
 */
void
ParkHelper::unpark ()
{
  using namespace ::java::lang;
  LONG volatile* ptr = &permit;

  // If this thread is in state RUNNING, give it a permit and return
  // immediately.
  if (compare_and_exchange
      (ptr, Thread::THREAD_PARK_RUNNING, Thread::THREAD_PARK_PERMIT))
    return;
  
  // If this thread is parked, put it into state RUNNING and send it a
  // signal.
  if (compare_and_exchange 
      (ptr, Thread::THREAD_PARK_PARKED, Thread::THREAD_PARK_RUNNING))
    {
      init_event ();
      SetEvent (event);
    }
}

/**
 * Blocks the thread until a matching _Jv_ThreadUnpark() occurs, the
 * thread is interrupted or the optional timeout expires.  If an
 * unpark call has already occurred, this also counts.  A timeout
 * value of zero is defined as no timeout.  When isAbsolute is true,
 * the timeout is in milliseconds relative to the epoch.  Otherwise,
 * the value is the number of nanoseconds which must occur before
 * timeout.  This call may also return spuriously (i.e.  for no
 * apparent reason).
 *
 * @param isAbsolute true if the timeout is specified in milliseconds from
 *                   the epoch.
 * @param time either the number of nanoseconds to wait, or a time in
 *             milliseconds from the epoch to wait for.
 */
void
ParkHelper::park (jboolean isAbsolute, jlong time)
{
  using namespace ::java::lang;
  LONG volatile* ptr = &permit;

  // If we have a permit, return immediately.
  if (compare_and_exchange 
      (ptr, Thread::THREAD_PARK_PERMIT, Thread::THREAD_PARK_RUNNING))
    return;

  // Determine the number of milliseconds to wait.
  jlong millis = 0, nanos = 0;
  
  if (time)
    {
      if (isAbsolute)
	{
	  millis = time - ::java::lang::System::currentTimeMillis();
	  nanos = 0;
	}
      else
	{
	  millis = 0;
	  nanos = time;
	}
	
      if (nanos)
        {
          millis += nanos / 1000000;
          if (millis == 0)
            millis = 1;
            // ...otherwise, we'll block indefinitely.
        }
    }
    
  if (millis < 0) return;
      // Can this ever happen?
      
  if (compare_and_exchange 
      (ptr, Thread::THREAD_PARK_RUNNING, Thread::THREAD_PARK_PARKED))
    {
      init_event();
      
      DWORD timeout = millis==0 ? INFINITE : (DWORD) millis;
      WaitForSingleObject (event, timeout);
      
      // If we were unparked by some other thread, this will already
      // be in state THREAD_PARK_RUNNING.  If we timed out, we have to
      // do it ourself.
      compare_and_exchange 
	(ptr, Thread::THREAD_PARK_PARKED, Thread::THREAD_PARK_RUNNING);
    }
}
OpenPOWER on IntegriCloud