--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/persistentstorage/sqlite3api/SQLite/mutex_w32.c Fri Jan 22 11:06:30 2010 +0200
@@ -0,0 +1,244 @@
+/*
+** 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 1.11 2008/06/26 10:41:19 danielk1977 Exp $
+*/
+#include "sqliteInt.h"
+
+/*
+** The code in this file is only used if we are compiling multithreaded
+** on a win32 system.
+*/
+#ifdef SQLITE_MUTEX_W32
+
+/*
+** Each recursive mutex is an instance of the following structure.
+*/
+struct sqlite3_mutex {
+ CRITICAL_SECTION mutex; /* Mutex controlling the lock */
+ int id; /* Mutex type */
+ int nRef; /* Number of enterances */
+ DWORD owner; /* Thread holding this mutex */
+};
+
+/*
+** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
+** or WinCE. Return false (zero) for Win95, Win98, or WinME.
+**
+** Here is an interesting observation: Win95, Win98, and WinME lack
+** the LockFileEx() API. But we can still statically link against that
+** API as long as we don't call it win running Win95/98/ME. A call to
+** this routine is used to determine if the host is Win95/98/ME or
+** WinNT/2K/XP so that we will know whether or not we can safely call
+** the LockFileEx() API.
+*/
+#if SQLITE_OS_WINCE
+# define mutexIsNT() (1)
+#else
+ static int mutexIsNT(void){
+ static int osType = 0;
+ if( osType==0 ){
+ OSVERSIONINFO sInfo;
+ sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+ GetVersionEx(&sInfo);
+ osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
+ }
+ return osType==2;
+ }
+#endif /* SQLITE_OS_WINCE */
+
+
+#ifdef SQLITE_DEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use only inside assert() statements.
+*/
+static int winMutexHeld(sqlite3_mutex *p){
+ return p->nRef!=0 && p->owner==GetCurrentThreadId();
+}
+static int winMutexNotheld(sqlite3_mutex *p){
+ return p->nRef==0 || p->owner!=GetCurrentThreadId();
+}
+#endif
+
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int winMutexInit(void){ return SQLITE_OK; }
+static int winMutexEnd(void){ 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:
+**
+** <ul>
+** <li> SQLITE_MUTEX_FAST 0
+** <li> SQLITE_MUTEX_RECURSIVE 1
+** <li> SQLITE_MUTEX_STATIC_MASTER 2
+** <li> SQLITE_MUTEX_STATIC_MEM 3
+** <li> SQLITE_MUTEX_STATIC_PRNG 4
+** </ul>
+**
+** The first two constants cause sqlite3_mutex_alloc() to create
+** a new mutex. The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to. But SQLite will only request a recursive mutex in
+** cases where it really needs one. If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** The other allowed parameters to sqlite3_mutex_alloc() each return
+** a pointer to a static preexisting mutex. Three static mutexes are
+** used by the current version of SQLite. Future versions of SQLite
+** may add additional static mutexes. Static mutexes are for internal
+** use by SQLite only. Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call. But for the static
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+*/
+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: {
+ static sqlite3_mutex staticMutexes[6];
+ static int isInit = 0;
+ while( !isInit ){
+ static long lock = 0;
+ if( InterlockedIncrement(&lock)==1 ){
+ int i;
+ for(i=0; i<sizeof(staticMutexes)/sizeof(staticMutexes[0]); i++){
+ InitializeCriticalSection(&staticMutexes[i].mutex);
+ }
+ isInit = 1;
+ }else{
+ Sleep(1);
+ }
+ }
+ assert( iType-2 >= 0 );
+ assert( iType-2 < sizeof(staticMutexes)/sizeof(staticMutexes[0]) );
+ p = &staticMutexes[iType-2];
+ p->id = iType;
+ break;
+ }
+ }
+ return p;
+}
+
+
+/*
+** This routine deallocates a previously
+** allocated mutex. SQLite is careful to deallocate every
+** mutex that it allocates.
+*/
+static void winMutexFree(sqlite3_mutex *p){
+ assert( p );
+ assert( p->nRef==0 );
+ assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+ DeleteCriticalSection(&p->mutex);
+ sqlite3_free(p);
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex. If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY. The sqlite3_mutex_try() interface returns SQLITE_OK
+** 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 winMutexEnter(sqlite3_mutex *p){
+ assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld(p) );
+ EnterCriticalSection(&p->mutex);
+ p->owner = GetCurrentThreadId();
+ p->nRef++;
+}
+static int winMutexTry(sqlite3_mutex *p){
+ int rc = SQLITE_BUSY;
+ assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld(p) );
+ /*
+ ** The sqlite3_mutex_try() routine is very rarely used, and when it
+ ** is used it is merely an optimization. So it is OK for it to always
+ ** fail.
+ **
+ ** The TryEnterCriticalSection() interface is only available on WinNT.
+ ** And some windows compilers complain if you try to use it without
+ ** first doing some #defines that prevent SQLite from building on Win98.
+ ** For that reason, we will omit this optimization for now. See
+ ** ticket #2685.
+ */
+#if 0
+ if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){
+ p->owner = GetCurrentThreadId();
+ p->nRef++;
+ rc = SQLITE_OK;
+ }
+#endif
+ return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread. The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated. SQLite will never do either.
+*/
+static void winMutexLeave(sqlite3_mutex *p){
+ assert( p->nRef>0 );
+ assert( p->owner==GetCurrentThreadId() );
+ p->nRef--;
+ assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
+ LeaveCriticalSection(&p->mutex);
+}
+
+sqlite3_mutex_methods *sqlite3DefaultMutex(void){
+ static sqlite3_mutex_methods sMutex = {
+ winMutexInit,
+ winMutexEnd,
+ winMutexAlloc,
+ winMutexFree,
+ winMutexEnter,
+ winMutexTry,
+ winMutexLeave,
+#ifdef SQLITE_DEBUG
+ winMutexHeld,
+ winMutexNotheld
+#endif
+ };
+
+ return &sMutex;
+}
+#endif /* SQLITE_MUTEX_W32 */