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-/*
-** 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
-*/
-#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 */
-#ifdef SQLITE_DEBUG
- int trace; /* True to trace changes */
-#endif
-};
-
-#ifdef SQLITE_DEBUG
-#define SQLITE3_MUTEX_INITIALIZER { 0, 0, 0 }
-#else
-#define SQLITE3_MUTEX_INITIALIZER { 0, 0 }
-#endif
-
-/*
-** 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
-** <li> SQLITE_MUTEX_RECURSIVE
-** <li> SQLITE_MUTEX_STATIC_MASTER
-** <li> SQLITE_MUTEX_STATIC_MEM
-** <li> SQLITE_MUTEX_STATIC_MEM2
-** <li> SQLITE_MUTEX_STATIC_PRNG
-** <li> SQLITE_MUTEX_STATIC_LRU
-** <li> SQLITE_MUTEX_STATIC_LRU2
-** </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. Six 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[6] = {
- SQLITE3_MUTEX_INITIALIZER,
- SQLITE3_MUTEX_INITIALIZER,
- SQLITE3_MUTEX_INITIALIZER,
- SQLITE3_MUTEX_INITIALIZER,
- SQLITE3_MUTEX_INITIALIZER,
- SQLITE3_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 ){
- unsigned 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){
-#ifdef SQLITE_DEBUG
- TID tid;
- PID pid;
- ULONG ulCount;
- DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
- assert( ulCount==0 );
- assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
-#endif
- DosCloseMutexSem( p->mutex );
- sqlite3_free( p );
-}
-
-#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;
- DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
- if( ulCount==0 || ( ulCount>1 && p->id!=SQLITE_MUTEX_RECURSIVE ) )
- return 0;
- DosGetInfoBlocks(&ptib, NULL);
- return tid==ptib->tib_ptib2->tib2_ultid;
-}
-static int os2MutexNotheld(sqlite3_mutex *p){
- TID tid;
- PID pid;
- ULONG ulCount;
- PTIB ptib;
- DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
- if( ulCount==0 )
- return 1;
- DosGetInfoBlocks(&ptib, NULL);
- return tid!=ptib->tib_ptib2->tib2_ultid;
-}
-static void os2MutexTrace(sqlite3_mutex *p, char *pAction){
- TID tid;
- PID pid;
- ULONG ulCount;
- DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
- printf("%s mutex %p (%d) with nRef=%ld\n", pAction, (void*)p, p->trace, ulCount);
-}
-#endif
-
-/*
-** 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){
- assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
- DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);
-#ifdef SQLITE_DEBUG
- if( p->trace ) os2MutexTrace(p, "enter");
-#endif
-}
-static int os2MutexTry(sqlite3_mutex *p){
- int rc = SQLITE_BUSY;
- assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
- if( DosRequestMutexSem(p->mutex, SEM_IMMEDIATE_RETURN) == NO_ERROR ) {
- rc = SQLITE_OK;
-#ifdef SQLITE_DEBUG
- if( p->trace ) os2MutexTrace(p, "try");
-#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 os2MutexLeave(sqlite3_mutex *p){
- assert( os2MutexHeld(p) );
- DosReleaseMutexSem(p->mutex);
-#ifdef SQLITE_DEBUG
- if( p->trace ) os2MutexTrace(p, "leave");
-#endif
-}
-
-sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
- static const sqlite3_mutex_methods sMutex = {
- os2MutexInit,
- os2MutexEnd,
- os2MutexAlloc,
- os2MutexFree,
- os2MutexEnter,
- os2MutexTry,
- os2MutexLeave,
-#ifdef SQLITE_DEBUG
- os2MutexHeld,
- os2MutexNotheld
-#else
- 0,
- 0
-#endif
- };
-
- return &sMutex;
-}
-#endif /* SQLITE_MUTEX_OS2 */
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