--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/persistentstorage/sqlite3api/SQLite/mutex_os2.c Fri Jan 22 11:06:30 2010 +0200
@@ -0,0 +1,273 @@
+/*
+** 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 C functions that implement mutexes for OS/2
+**
+** $Id: mutex_os2.c,v 1.10 2008/06/23 22:13:28 pweilbacher Exp $
+*/
+#include "sqliteInt.h"
+
+/*
+** The code in this file is only used if SQLITE_MUTEX_OS2 is defined.
+** See the mutex.h file for details.
+*/
+#ifdef SQLITE_MUTEX_OS2
+
+/********************** OS/2 Mutex Implementation **********************
+**
+** This implementation of mutexes is built using the OS/2 API.
+*/
+
+/*
+** The mutex object
+** Each recursive mutex is an instance of the following structure.
+*/
+struct sqlite3_mutex {
+ HMTX mutex; /* Mutex controlling the lock */
+ int id; /* Mutex type */
+ int nRef; /* Number of references */
+ TID owner; /* Thread holding this mutex */
+};
+
+#define OS2_MUTEX_INITIALIZER 0,0,0,0
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int os2MutexInit(void){ return SQLITE_OK; }
+static int os2MutexEnd(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 *os2MutexAlloc(int iType){
+ sqlite3_mutex *p = NULL;
+ switch( iType ){
+ case SQLITE_MUTEX_FAST:
+ case SQLITE_MUTEX_RECURSIVE: {
+ p = sqlite3MallocZero( sizeof(*p) );
+ if( p ){
+ p->id = iType;
+ if( DosCreateMutexSem( 0, &p->mutex, 0, FALSE ) != NO_ERROR ){
+ sqlite3_free( p );
+ p = NULL;
+ }
+ }
+ break;
+ }
+ default: {
+ static volatile int isInit = 0;
+ static sqlite3_mutex staticMutexes[] = {
+ { OS2_MUTEX_INITIALIZER, },
+ { OS2_MUTEX_INITIALIZER, },
+ { OS2_MUTEX_INITIALIZER, },
+ { OS2_MUTEX_INITIALIZER, },
+ { OS2_MUTEX_INITIALIZER, },
+ { OS2_MUTEX_INITIALIZER, },
+ };
+ if ( !isInit ){
+ APIRET rc;
+ PTIB ptib;
+ PPIB ppib;
+ HMTX mutex;
+ char name[32];
+ DosGetInfoBlocks( &ptib, &ppib );
+ sqlite3_snprintf( sizeof(name), name, "\\SEM32\\SQLITE%04x",
+ ppib->pib_ulpid );
+ while( !isInit ){
+ mutex = 0;
+ rc = DosCreateMutexSem( name, &mutex, 0, FALSE);
+ if( rc == NO_ERROR ){
+ int i;
+ if( !isInit ){
+ for( i = 0; i < sizeof(staticMutexes)/sizeof(staticMutexes[0]); i++ ){
+ DosCreateMutexSem( 0, &staticMutexes[i].mutex, 0, FALSE );
+ }
+ isInit = 1;
+ }
+ DosCloseMutexSem( mutex );
+ }else if( rc == ERROR_DUPLICATE_NAME ){
+ DosSleep( 1 );
+ }else{
+ return p;
+ }
+ }
+ }
+ 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 os2MutexFree(sqlite3_mutex *p){
+ if( p==0 ) return;
+ assert( p->nRef==0 );
+ assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+ DosCloseMutexSem( 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 os2MutexEnter(sqlite3_mutex *p){
+ TID tid;
+ PID holder1;
+ ULONG holder2;
+ if( p==0 ) return;
+ assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
+ DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);
+ DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
+ p->owner = tid;
+ p->nRef++;
+}
+static int os2MutexTry(sqlite3_mutex *p){
+ int rc;
+ TID tid;
+ PID holder1;
+ ULONG holder2;
+ if( p==0 ) return SQLITE_OK;
+ assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
+ if( DosRequestMutexSem(p->mutex, SEM_IMMEDIATE_RETURN) == NO_ERROR) {
+ DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
+ p->owner = tid;
+ p->nRef++;
+ rc = SQLITE_OK;
+ } else {
+ rc = SQLITE_BUSY;
+ }
+
+ 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 os2MutexLeave(sqlite3_mutex *p){
+ TID tid;
+ PID holder1;
+ ULONG holder2;
+ if( p==0 ) return;
+ assert( p->nRef>0 );
+ DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
+ assert( p->owner==tid );
+ p->nRef--;
+ assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
+ DosReleaseMutexSem(p->mutex);
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+static int os2MutexHeld(sqlite3_mutex *p){
+ TID tid;
+ PID pid;
+ ULONG ulCount;
+ PTIB ptib;
+ if( p!=0 ) {
+ DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
+ } else {
+ DosGetInfoBlocks(&ptib, NULL);
+ tid = ptib->tib_ptib2->tib2_ultid;
+ }
+ return p==0 || (p->nRef!=0 && p->owner==tid);
+}
+static int os2MutexNotheld(sqlite3_mutex *p){
+ TID tid;
+ PID pid;
+ ULONG ulCount;
+ PTIB ptib;
+ if( p!= 0 ) {
+ DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
+ } else {
+ DosGetInfoBlocks(&ptib, NULL);
+ tid = ptib->tib_ptib2->tib2_ultid;
+ }
+ return p==0 || p->nRef==0 || p->owner!=tid;
+}
+#endif
+
+sqlite3_mutex_methods *sqlite3DefaultMutex(void){
+ static sqlite3_mutex_methods sMutex = {
+ os2MutexInit,
+ os2MutexEnd,
+ os2MutexAlloc,
+ os2MutexFree,
+ os2MutexEnter,
+ os2MutexTry,
+ os2MutexLeave,
+#ifdef SQLITE_DEBUG
+ os2MutexHeld,
+ os2MutexNotheld
+#endif
+ };
+
+ return &sMutex;
+}
+#endif /* SQLITE_MUTEX_OS2 */