1                 : /*
       2                 :  * Copyright (c) 2011 The Native Client Authors. All rights reserved.
       3                 :  * Use of this source code is governed by a BSD-style license that can be
       4                 :  * found in the LICENSE file.
       5                 :  */
       6                 : 
       7                 : #include <pthread.h>
       8                 : #include <sys/time.h>
       9                 : #include "native_client/src/shared/platform/nacl_sync.h"
      10                 : #include "native_client/src/include/atomic_ops.h"
      11                 : #include "native_client/src/include/nacl_base.h"
      12                 : #include "native_client/src/include/nacl_macros.h"
      13                 : #include "native_client/src/trusted/service_runtime/include/sys/time.h"
      14                 : 
      15                 : static const uint64_t kMicrosecondsPerSecond = 1000 * 1000;
      16                 : static const uint64_t kNanosecondsPerMicrosecond = 1000;
      17                 : 
      18                 : #if NACL_COND_BROADCAST_HACK
      19                 : #define ATOMIC_INC(_var)  (AtomicIncrement((_var), (Atomic32)1))
      20                 : #define ATOMIC_DEC(_var)  (AtomicIncrement((_var), (Atomic32)-1))
      21                 : #endif
      22                 : 
      23                 : /* Condition variable C API */
      24                 : 
      25             265 : int NaClCondVarCtor(struct NaClCondVar  *cvp) {
      26             265 :   if (0 != pthread_cond_init(&cvp->cv, (pthread_condattr_t *) 0)) {
      27               0 :     return 0;
      28                 :   }
      29                 : #if NACL_COND_BROADCAST_HACK
      30                 :   cvp->waiting = 0;
      31                 : #endif
      32             265 :   return 1;
      33                 : }
      34                 : 
      35             208 : void NaClCondVarDtor(struct NaClCondVar *cvp) {
      36             208 :   pthread_cond_destroy(&cvp->cv);
      37             208 : }
      38                 : 
      39            1052 : NaClSyncStatus NaClCondVarSignal(struct NaClCondVar *cvp) {
      40            1052 :   pthread_cond_signal(&cvp->cv);
      41            1052 :   return NACL_SYNC_OK;
      42                 : }
      43                 : 
      44                 : #if NACL_COND_BROADCAST_HACK
      45                 : /* Strange linking bug:
      46                 :  * If pthread_cond_broadcast is not referenced in this file, then
      47                 :  * the function is never linked in, but libstdc++ tries to use it
      48                 :  * anyway, resulting in an exception being thrown.
      49                 :  * BUG= http://code.google.com/p/nativeclient/issues/detail?id=1987
      50                 :  */
      51                 : int (*fake_reference_to_pthread_cond_broadcast)(pthread_cond_t*) =
      52                 :     pthread_cond_broadcast;
      53                 : #endif
      54                 : 
      55              31 : NaClSyncStatus NaClCondVarBroadcast(struct NaClCondVar *cvp) {
      56                 : #if NACL_COND_BROADCAST_HACK
      57                 :   /* There is a race condition where cvp->waiting may be
      58                 :    * incremented before a thread actually calls pthread_cond_(timed)wait.
      59                 :    * In that case, we'll send an extra signal and it'll go nowhere.
      60                 :    * This is not a problem, because broadcasting always
      61                 :    * has this race condition. If both the broadcast and
      62                 :    * wait are protected by the same mutex, then the waiting counter
      63                 :    * will be accurate
      64                 :    */
      65                 :   uint32_t waiting = cvp->waiting;
      66                 :   while (waiting > 0) {
      67                 :     pthread_cond_signal(&cvp->cv);
      68                 :     waiting--;
      69                 :   }
      70                 : #else
      71              31 :   pthread_cond_broadcast(&cvp->cv);
      72                 : #endif
      73              31 :   return NACL_SYNC_OK;
      74                 : }
      75                 : 
      76                 : NaClSyncStatus NaClCondVarWait(struct NaClCondVar *cvp,
      77             245 :                                struct NaClMutex   *mp) {
      78                 : #if NACL_COND_BROADCAST_HACK
      79                 :   ATOMIC_INC(&cvp->waiting);
      80                 : #endif
      81             245 :   pthread_cond_wait(&cvp->cv, &mp->mu);
      82                 : #if NACL_COND_BROADCAST_HACK
      83                 :   ATOMIC_DEC(&cvp->waiting);
      84                 : #endif
      85             245 :   return NACL_SYNC_OK;
      86                 : }
      87                 : 
      88                 : NaClSyncStatus NaClCondVarTimedWaitRelative(
      89                 :     struct NaClCondVar             *cvp,
      90                 :     struct NaClMutex               *mp,
      91               0 :     NACL_TIMESPEC_T const          *reltime) {
      92                 :   uint64_t relative_wait_us =
      93                 :       reltime->tv_sec * kMicrosecondsPerSecond +
      94               0 :       reltime->tv_nsec / kNanosecondsPerMicrosecond;
      95                 :   uint64_t current_time_us;
      96                 :   uint64_t wakeup_time_us;
      97                 :   int result;
      98                 :   struct timespec ts;
      99                 :   struct timeval tv;
     100               0 :   struct timezone tz = { 0, 0 };  /* UTC */
     101               0 :   if (gettimeofday(&tv, &tz) == 0) {
     102               0 :     current_time_us = tv.tv_sec * kMicrosecondsPerSecond + tv.tv_usec;
     103                 :   } else {
     104               0 :     return NACL_SYNC_INTERNAL_ERROR;
     105                 :   }
     106               0 :   wakeup_time_us = current_time_us + relative_wait_us;
     107               0 :   ts.tv_sec = wakeup_time_us / kMicrosecondsPerSecond;
     108               0 :   ts.tv_nsec = (wakeup_time_us - ts.tv_sec * kMicrosecondsPerSecond) *
     109                 :                kNanosecondsPerMicrosecond;
     110                 : 
     111                 : #if NACL_COND_BROADCAST_HACK
     112                 :   ATOMIC_INC(&cvp->waiting);
     113                 : #endif
     114               0 :   result = pthread_cond_timedwait(&cvp->cv, &mp->mu, &ts);
     115                 : #if NACL_COND_BROADCAST_HACK
     116                 :   ATOMIC_DEC(&cvp->waiting);
     117                 : #endif
     118               0 :   if (0 == result) {
     119               0 :     return NACL_SYNC_OK;
     120                 :   }
     121               0 :   return NACL_SYNC_CONDVAR_TIMEDOUT;
     122                 : }
     123                 : 
     124                 : NaClSyncStatus NaClCondVarTimedWaitAbsolute(
     125                 :     struct NaClCondVar              *cvp,
     126                 :     struct NaClMutex                *mp,
     127               0 :     NACL_TIMESPEC_T const           *abstime) {
     128                 :   struct timespec ts;
     129                 :   int result;
     130               0 :   ts.tv_sec = abstime->tv_sec;
     131               0 :   ts.tv_nsec = abstime->tv_nsec;
     132                 : #if NACL_COND_BROADCAST_HACK
     133                 :   ATOMIC_INC(&cvp->waiting);
     134                 : #endif
     135               0 :   result = pthread_cond_timedwait(&cvp->cv, &mp->mu, &ts);
     136                 : #if NACL_COND_BROADCAST_HACK
     137                 :   ATOMIC_DEC(&cvp->waiting);
     138                 : #endif
     139               0 :   if (0 == result) {
     140               0 :     return NACL_SYNC_OK;
     141                 :   }
     142               0 :   return NACL_SYNC_CONDVAR_TIMEDOUT;
     143                 : }