/*

** 2007 August 28

**

** 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 common header for all mutex implementations.

** The sqliteInt.h header #includes this file so that it is available

** to all source files.  We break it out in an effort to keep the code

** better organized.

**

** NOTE:  source files should *not* #include this header file directly.

** Source files should #include the sqliteInt.h file and let that file

** include this one indirectly.

**

** $Id: mutex.h,v 1.9 2008/10/07 15:25:48 drh Exp $

*/

/*

** Figure out what version of the code to use.  The choices are

**

**   SQLITE_MUTEX_OMIT         No mutex logic.  Not even stubs.  The

**                             mutexes implemention cannot be overridden

**                             at start-time.

**

**   SQLITE_MUTEX_NOOP         For single-threaded applications.  No

**                             mutual exclusion is provided.  But this

**                             implementation can be overridden at

**                             start-time.

**

**   SQLITE_MUTEX_PTHREADS     For multi-threaded applications on Unix.

**

**   SQLITE_MUTEX_W32          For multi-threaded applications on Win32.

**

**   SQLITE_MUTEX_OS2          For multi-threaded applications on OS/2.

*/

#if !SQLITE_THREADSAFE

# define SQLITE_MUTEX_OMIT

#endif

#if SQLITE_THREADSAFE && !defined(SQLITE_MUTEX_NOOP)

#  if SQLITE_OS_UNIX

#    define SQLITE_MUTEX_PTHREADS

#  elif SQLITE_OS_WIN

#    define SQLITE_MUTEX_W32

#  elif SQLITE_OS_OS2

#    define SQLITE_MUTEX_OS2

#  else

#    define SQLITE_MUTEX_NOOP

#  endif

#endif

#ifdef SQLITE_MUTEX_OMIT

/*

** If this is a no-op implementation, implement everything as macros.

*/

#define sqlite3_mutex_alloc(X)    ((sqlite3_mutex*)8)

#define sqlite3_mutex_free(X)

#define sqlite3_mutex_enter(X)

#define sqlite3_mutex_try(X)      SQLITE_OK

#define sqlite3_mutex_leave(X)

#define sqlite3_mutex_held(X)     1

#define sqlite3_mutex_notheld(X)  1

#define sqlite3MutexAlloc(X)      ((sqlite3_mutex*)8)

#define sqlite3MutexInit()        SQLITE_OK

#define sqlite3MutexEnd()

#endif /* defined(SQLITE_OMIT_MUTEX) */