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Overview
Comment:A new version of the slow mutex log that uses gettimeofday() instead of trying to access the hardware timer.
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SHA1: 92b9fead353d50eb41f5ab7e3a887dd4e5c3aa80
User & Date: drh 2016-07-30 03:33:30
Context
2016-08-04
14:08
Add extra logging calls to this branch. check-in: 491f1ef3 user: dan tags: debug
2016-07-30
03:33
A new version of the slow mutex log that uses gettimeofday() instead of trying to access the hardware timer. check-in: 92b9fead user: drh tags: debug
2016-07-29
16:32
Turn memory status off by default. check-in: ea3c7162 user: drh tags: debug
Changes
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Changes to src/mutex_unix.c.

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static void pthreadMutexFree(sqlite3_mutex *p){
  assert( p->nRef==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
  pthread_mutex_destroy(&p->mutex);
  sqlite3_free(p);
}

#include "hwtime.h"
#ifdef SQLITE_MUTEX_NREF
# define MUTEX_ID(p)  (p->id)
#else
# define MUTEX_ID(p)  0
#endif

/*
................................................................................
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void pthreadMutexEnter(sqlite3_mutex *p){

  sqlite3_uint64 iTimer = sqlite3Hwtime();
  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );



#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
  /* If recursive mutexes are not available, then we have to grow
  ** our own.  This implementation assumes that pthread_equal()
  ** is atomic - that it cannot be deceived into thinking self
  ** and p->owner are equal if p->owner changes between two values
  ** that are not equal to self while the comparison is taking place.
  ** This implementation also assumes a coherent cache - that 
................................................................................
  */
  pthread_mutex_lock(&p->mutex);
#if SQLITE_MUTEX_NREF
  assert( p->nRef>0 || p->owner==0 );
  p->owner = pthread_self();
  p->nRef++;
#endif
  iTimer = sqlite3Hwtime() - iTimer;
  if( iTimer>100000 ){

    sqlite3_mutex *pMaster = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
    int id = -1;
    if( p>=pMaster && p<=&pMaster[SQLITE_MUTEX_STATIC_APP3-2] ){
      id = (int)(p - pMaster) + 2;
    }
    sqlite3_log(SQLITE_NOTICE, "slow mutex: %lld cycles on %d/%p",
                iTimer, id, p);
  }
#endif

#ifdef SQLITE_DEBUG
  if( p->trace ){
    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }







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static void pthreadMutexFree(sqlite3_mutex *p){
  assert( p->nRef==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
  pthread_mutex_destroy(&p->mutex);
  sqlite3_free(p);
}

#include <sys/time.h>
#ifdef SQLITE_MUTEX_NREF
# define MUTEX_ID(p)  (p->id)
#else
# define MUTEX_ID(p)  0
#endif

/*
................................................................................
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void pthreadMutexEnter(sqlite3_mutex *p){
  struct timeval x;
  sqlite3_uint64 iBegin, iEnd;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );

  gettimeofday(&x, 0);
  iBegin = 1000000*(sqlite3_uint64)x.tv_sec + x.tv_usec;
#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
  /* If recursive mutexes are not available, then we have to grow
  ** our own.  This implementation assumes that pthread_equal()
  ** is atomic - that it cannot be deceived into thinking self
  ** and p->owner are equal if p->owner changes between two values
  ** that are not equal to self while the comparison is taking place.
  ** This implementation also assumes a coherent cache - that 
................................................................................
  */
  pthread_mutex_lock(&p->mutex);
#if SQLITE_MUTEX_NREF
  assert( p->nRef>0 || p->owner==0 );
  p->owner = pthread_self();
  p->nRef++;
#endif
  gettimeofday(&x, 0);
  iEnd = 1000000*(sqlite3_uint64)x.tv_sec + x.tv_usec;
  if( iEnd > iBegin+500 ){
    sqlite3_mutex *pMaster = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
    int id = -1;
    if( p>=pMaster && p<=&pMaster[SQLITE_MUTEX_STATIC_APP3-2] ){
      id = (int)(p - pMaster) + 2;
    }
    sqlite3_log(SQLITE_NOTICE, "slow mutex: %llu uS on %d/%p",
                iEnd - iBegin, id, p);
  }
#endif

#ifdef SQLITE_DEBUG
  if( p->trace ){
    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }