/*
** 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.
*/
void sqlite3_mutex_enter(sqlite3_mutex *p){
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
EnterCriticalSection(&p->mutex);
p->owner = GetCurrentThreadId();
p->nRef++;
}
/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no
** such buffer exists or there is no space left in it, this function falls
** back to sqlite3Malloc().
**
** Multiple threads can run this routine at the same time. Global variables
** in pcache1 need to be protected via mutex.
*/
static void *pcache1Alloc(int nByte){
void *p = 0;
assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
if( nByte<=pcache1.szSlot ){
sqlite3_mutex_enter(pcache1.mutex);
p = (PgHdr1 *)pcache1.pFree;
if( p ){
pcache1.pFree = pcache1.pFree->pNext;
pcache1.nFreeSlot--;
pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
assert( pcache1.nFreeSlot>=0 );
sqlite3StatusHighwater(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
sqlite3StatusUp(SQLITE_STATUS_PAGECACHE_USED, 1);
}
sqlite3_mutex_leave(pcache1.mutex);
}
if( p==0 ){
/* Memory is not available in the SQLITE_CONFIG_PAGECACHE pool. Get
** it from sqlite3Malloc instead.
*/
p = sqlite3Malloc(nByte);
#ifndef SQLITE_DISABLE_PAGECACHE_OVERFLOW_STATS
if( p ){
int sz = sqlite3MallocSize(p);
sqlite3_mutex_enter(pcache1.mutex);
sqlite3StatusHighwater(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
sqlite3StatusUp(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
sqlite3_mutex_leave(pcache1.mutex);
}
#endif
sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
}
return p;
}
void *sqlite3ScratchMalloc(int n){
void *p;
assert( n>0 );
sqlite3_mutex_enter(mem0.mutex);
if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
p = mem0.pScratchFree;
mem0.pScratchFree = mem0.pScratchFree->pNext;
mem0.nScratchFree--;
sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);
sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
sqlite3_mutex_leave(mem0.mutex);
}else{
if( sqlite3GlobalConfig.bMemstat ){
sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
n = mallocWithAlarm(n, &p);
if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
sqlite3_mutex_leave(mem0.mutex);
}else{
sqlite3_mutex_leave(mem0.mutex);
p = sqlite3GlobalConfig.m.xMalloc(n);
}
sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
}
assert( sqlite3_mutex_notheld(mem0.mutex) );
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
assert( scratchAllocOut<=1 );
if( p ) scratchAllocOut++;
#endif
return p;
}
/*
** Obtain the BtShared mutex associated with B-Tree handle p. Also,
** set BtShared.db to the database handle associated with p and the
** p->locked boolean to true.
*/
static void lockBtreeMutex(Btree *p){
assert( p->locked==0 );
assert( sqlite3_mutex_notheld(p->pBt->mutex) );
assert( sqlite3_mutex_held(p->db->mutex) );
sqlite3_mutex_enter(p->pBt->mutex);
p->pBt->db = p->db;
p->locked = 1;
}
/*
** 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.
*/
void sqlite3_mutex_enter(sqlite3_mutex *p){
TID tid;
PID holder1;
ULONG holder2;
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);
DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
p->owner = tid;
p->nRef++;
}
/*
** 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.
*/
void sqlite3_mutex_enter(sqlite3_mutex *p){
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
pthread_mutex_lock(&p->mutex);
p->owner = pthread_self();
p->nRef++;
#ifdef SQLITE_DEBUG
if( p->trace ){
printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
}
#endif
}
int sqlite3_mutex_try(sqlite3_mutex *p){
int rc;
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
//if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){
// p->owner = GetCurrentThreadId();
// p->nRef++;
// rc = SQLITE_OK;
//}else{
rc = SQLITE_BUSY;
//}
return rc;
}
int sqlite3_mutex_try(sqlite3_mutex *p){
int rc;
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
/* If recursive mutexes are not available, then we have to grow
** our own. This implementation assumes that pthread_equal()
** is atomic - that it cannot be deceived into thinking self
** and p->owner are equal if p->owner changes between two values
** that are not equal to self while the comparison is taking place.
** This implementation also assumes a coherent cache - that
** separate processes cannot read different values from the same
** address at the same time. If either of these two conditions
** are not met, then the mutexes will fail and problems will result.
*/
{
pthread_t self = pthread_self();
if( p->nRef>0 && pthread_equal(p->owner, self) ){
p->nRef++;
rc = SQLITE_OK;
}else if( pthread_mutex_lock(&p->mutex)==0 ){
assert( p->nRef==0 );
p->owner = self;
p->nRef = 1;
rc = SQLITE_OK;
}else{
rc = SQLITE_BUSY;
}
}
#else
/* Use the built-in recursive mutexes if they are available.
*/
if( pthread_mutex_trylock(&p->mutex)==0 ){
p->owner = pthread_self();
p->nRef++;
rc = SQLITE_OK;
}else{
rc = SQLITE_BUSY;
}
#endif
#ifdef SQLITE_DEBUG
if( rc==SQLITE_OK && p->trace ){
printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
}
#endif
return rc;
}
int sqlite3_mutex_try(sqlite3_mutex *p){
int rc;
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
if( pthread_mutex_trylock(&p->mutex)==0 ){
p->owner = pthread_self();
p->nRef++;
rc = SQLITE_OK;
#ifdef SQLITE_DEBUG
if( p->trace ){
printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
}
#endif
}else{
rc = SQLITE_BUSY;
}
return rc;
}
int sqlite3_mutex_try(sqlite3_mutex *p){
int rc;
TID tid;
PID holder1;
ULONG holder2;
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(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;
}
/*
** Allocate memory that is to be used and released right away.
** This routine is similar to alloca() in that it is not intended
** for situations where the memory might be held long-term. This
** routine is intended to get memory to old large transient data
** structures that would not normally fit on the stack of an
** embedded processor.
*/
void *sqlite3ScratchMalloc(int n){
void *p;
assert( n>0 );
sqlite3_mutex_enter(mem0.mutex);
if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
p = mem0.pScratchFree;
mem0.pScratchFree = mem0.pScratchFree->pNext;
mem0.nScratchFree--;
sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);
sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
sqlite3_mutex_leave(mem0.mutex);
}else{
if( sqlite3GlobalConfig.bMemstat ){
sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
n = mallocWithAlarm(n, &p);
if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
sqlite3_mutex_leave(mem0.mutex);
}else{
sqlite3_mutex_leave(mem0.mutex);
p = sqlite3GlobalConfig.m.xMalloc(n);
}
sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
}
assert( sqlite3_mutex_notheld(mem0.mutex) );
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
/* Verify that no more than two scratch allocations per thread
** are outstanding at one time. (This is only checked in the
** single-threaded case since checking in the multi-threaded case
** would be much more complicated.) */
assert( scratchAllocOut<=1 );
if( p ) scratchAllocOut++;
#endif
return p;
}
/*
** Allocate memory that is to be used and released right away.
** This routine is similar to alloca() in that it is not intended
** for situations where the memory might be held long-term. This
** routine is intended to get memory to old large transient data
** structures that would not normally fit on the stack of an
** embedded processor.
*/
void *sqlite3ScratchMalloc(int n){
void *p;
assert( n>0 );
sqlite3_mutex_enter(mem0.mutex);
sqlite3StatusHighwater(SQLITE_STATUS_SCRATCH_SIZE, n);
if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
p = mem0.pScratchFree;
mem0.pScratchFree = mem0.pScratchFree->pNext;
mem0.nScratchFree--;
sqlite3StatusUp(SQLITE_STATUS_SCRATCH_USED, 1);
sqlite3_mutex_leave(mem0.mutex);
}else{
sqlite3_mutex_leave(mem0.mutex);
p = sqlite3Malloc(n);
if( sqlite3GlobalConfig.bMemstat && p ){
sqlite3_mutex_enter(mem0.mutex);
sqlite3StatusUp(SQLITE_STATUS_SCRATCH_OVERFLOW, sqlite3MallocSize(p));
sqlite3_mutex_leave(mem0.mutex);
}
sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
}
assert( sqlite3_mutex_notheld(mem0.mutex) );
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
/* EVIDENCE-OF: R-12970-05880 SQLite will not use more than one scratch
** buffers per thread.
**
** This can only be checked in single-threaded mode.
*/
assert( scratchAllocOut==0 );
if( p ) scratchAllocOut++;
#endif
return p;
}
int sqlite3_mutex_try(sqlite3_mutex *p){
int rc = SQLITE_BUSY;
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(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;
}
