/*

 ** 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) */