SQLite

/*
** 2007 August 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for win32
**
** $Id: mutex_w32.c,v 1.16 2009/06/01 17:06:08 shane Exp $
*/
#include "sqliteInt.h"

/*
** The code in this file is only used if we are compiling multithreaded
** on a win32 system.
*/

}
#endif


/*
** Initialize and deinitialize the mutex subsystem.
*/
static sqlite3_mutex winMutex_staticMutexes[6];
static int winMutex_isInit = 0;
/* As winMutexInit() and winMutexEnd() are called as part
** of the sqlite3_initialize and sqlite3_shutdown()
** processing, the "interlocked" magic is probably not
** strictly necessary.
*/
static long winMutex_lock = 0;

static int winMutexInit(void){ 
  /* The first to increment to 1 does actual initialization */
  if( InterlockedIncrement(&winMutex_lock)==1 ){
    int i;
    for(i=0; i<sizeof(winMutex_staticMutexes)/sizeof(winMutex_staticMutexes[0]); i++){
      InitializeCriticalSection(&winMutex_staticMutexes[i].mutex);
    }
    winMutex_isInit = 1;
  }else{
    while( !winMutex_isInit ){
      Sleep(1);
    }
  }
  return SQLITE_OK; 
}

static int winMutexEnd(void){ 
  /* The first to decrement to 0 does actual shutdown 
  ** (which should be the last to shutdown.) */
  if( InterlockedDecrement(&winMutex_lock)==0 ){
    if( winMutex_isInit==1 ){
      int i;
      for(i=0; i<sizeof(winMutex_staticMutexes)/sizeof(winMutex_staticMutexes[0]); i++){
        DeleteCriticalSection(&winMutex_staticMutexes[i].mutex);
      }
      winMutex_isInit = 0;
    }
  }
  return SQLITE_OK; 
}

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated.  SQLite
** will unwind its stack and return an error.  The argument
** to sqlite3_mutex_alloc() is one of these integer constants:

static sqlite3_mutex *winMutexAlloc(int iType){
  sqlite3_mutex *p;

  switch( iType ){
    case SQLITE_MUTEX_FAST:
    case SQLITE_MUTEX_RECURSIVE: {
      p = sqlite3MallocZero( sizeof(*p) );
      if( p ){  
        p->id = iType;
        InitializeCriticalSection(&p->mutex);
      }
      break;
    }
    default: {














      assert( iType-2 >= 0 );
      assert( iType-2 < sizeof(winMutex_staticMutexes)/sizeof(winMutex_staticMutexes[0]) );
      p = &winMutex_staticMutexes[iType-2];
      p->id = iType;
      break;
    }
  }
  return p;
}