void SocketService::attach(SocketPort *port)
{
enterMutex();
#ifdef USE_POLL
port->ufd = 0;
#endif
if(last)
last->next = port;
port->prev = last;
last = port;
FD_SET(port->so, &connect);
if(port->so >= hiwater)
hiwater = port->so + 1;
port->service = this;
++count;
if(!first) first = port;
// start thread if necessary
if (count == 1)
{
if (!isRunning())
{
leaveMutex();
start();
return;
}
}
leaveMutex();
update();
}
size_t Buffer::peek(void *buf)
{
size_t rc;
enterMutex();
if(!_used)
{
leaveMutex();
return 0;
}
rc = onPeek(buf);
leaveMutex();
return rc;
}
/*
** This is called when the database connection passed as an argument is
** being closed. The connection is removed from the blocked list.
*/
void sqlite3ConnectionClosed(sqlite3 *db){
sqlite3ConnectionUnlocked(db);
enterMutex();
removeFromBlockedList(db);
checkListProperties(db);
leaveMutex();
}
static jint
receiveBytes(SharedMemoryConnection *connection, void *bytes, jint length)
{
Stream *stream = &connection->incoming;
SharedStream *shared = stream->shared;
jint fragmentStart;
jint fragmentLength;
jint index = 0;
jint maxLength;
CHECK_ERROR(enterMutex(stream, connection->shutdown));
while (index < length) {
CHECK_ERROR(waitForData(connection, stream));
SHMEM_ASSERT(!EMPTY(stream));
fragmentStart = shared->readOffset;
if (fragmentStart < shared->writeOffset) {
maxLength = shared->writeOffset - fragmentStart;
} else {
maxLength = SHARED_BUFFER_SIZE - fragmentStart;
}
fragmentLength = MIN(maxLength, length - index);
memcpy((jbyte *)bytes + index, shared->buffer + fragmentStart, fragmentLength);
shared->readOffset = ADD_OFFSET(fragmentStart, fragmentLength);
index += fragmentLength;
shared->isFull = JNI_FALSE;
STREAM_INVARIANT(stream);
CHECK_ERROR(signalSpace(stream));
}
CHECK_ERROR(leaveMutex(stream));
return SYS_OK;
}
void ThreadQueue::run(void)
{
data_t *prev;
started = true;
for(;;)
{
Semaphore::wait();
if(!started)
sleep((timeout_t)~0);
startQueue();
while(first)
{
runQueue(first->data);
enterMutex();
prev = first;
first = first->next;
delete[] prev;
if(!first)
last = NULL;
leaveMutex();
if(first)
Semaphore::wait(); // demark semaphore
}
stopQueue();
}
}
/*
** This function is called while stepping or preparing a statement
** associated with connection db. The operation will return SQLITE_LOCKED
** to the user because it requires a lock that will not be available
** until connection pBlocker concludes its current transaction.
*/
void sqlite3ConnectionBlocked(sqlite3 *db, sqlite3 *pBlocker){
enterMutex();
if( db->pBlockingConnection==0 && db->pUnlockConnection==0 ){
addToBlockedList(db);
}
db->pBlockingConnection = pBlocker;
leaveMutex();
}
void MapTable::addFree(MapObject *obj)
{
obj->detach();
enterMutex();
obj->nextObject = map[range];
map[range] = obj;
leaveMutex();
}
void MapTable::cleanup(void)
{
enterMutex();
if(map)
delete[] map;
map = NULL;
leaveMutex();
}
size_t Buffer::wait(void *buf, timeout_t timeout)
{
size_t rc = 0;
enterMutex();
while(!_used)
{
if(!Conditional::wait(timeout, true))
{
leaveMutex();
return Buffer::timeout;
}
}
rc = (ssize_t)onWait(buf);
--_used;
Conditional::signal(false);
leaveMutex();
return rc;
}
void *SharedMemPager::alloc(size_t size)
{
void *mem;
enterMutex();
mem = MemPager::alloc(size);
leaveMutex();
return mem;
}
void *MapTable::getFree(void)
{
enterMutex();
MapObject *obj = map[range];
if(obj)
map[range] = obj->nextObject;
leaveMutex();
return obj;
}
void MapTable::addObject(MapObject &obj)
{
unsigned idx = getIndex(obj.idObject);
if(obj.table == this || !map)
return;
obj.detach();
enterMutex();
obj.nextObject = map[idx];
map[idx] = &obj;
leaveMutex();
}
/* enter the stream's mutex and (optionally) check for a closed stream */
static jint
enterMutex(Stream *stream, sys_event_t event)
{
jint ret = sysIPMutexEnter(stream->mutex, event);
if (ret != SYS_OK) {
return ret;
}
if (IS_STATE_CLOSED(stream->state)) {
(void)leaveMutex(stream);
return SYS_ERR;
}
return SYS_OK;
}
static jint
closeStream(Stream *stream, jboolean linger)
{
/*
* Lock stream during close - ignore shutdown event as we are
* closing down and shutdown should be signalled.
*/
CHECK_ERROR(enterMutex(stream, NULL));
/* mark the stream as closed */
stream->state = STATE_CLOSED;
/* wake up waitForData() if it is in sysEventWait() */
sysEventSignal(stream->hasData);
sysEventClose(stream->hasData);
/* wake up waitForSpace() if it is in sysEventWait() */
sysEventSignal(stream->hasSpace);
sysEventClose(stream->hasSpace);
/*
* If linger requested then give the stream a few seconds to
* drain before closing it.
*/
if (linger) {
int attempts = 10;
while (!EMPTY(stream) && attempts>0) {
CHECK_ERROR(leaveMutex(stream));
sysSleep(200);
CHECK_ERROR(enterMutex(stream, NULL));
attempts--;
}
}
CHECK_ERROR(leaveMutex(stream));
sysIPMutexClose(stream->mutex);
return SYS_OK;
}
/*
* Enter/exit with stream mutex held.
* On error, does not hold the stream mutex.
*/
static jint
waitForData(SharedMemoryConnection *connection, Stream *stream)
{
jint error = SYS_OK;
/* Assumes mutex is held on call */
while ((error == SYS_OK) && EMPTY(stream)) {
CHECK_ERROR(leaveMutex(stream));
error = sysEventWait(connection->otherProcess, stream->hasData);
if (error == SYS_OK) {
CHECK_ERROR(enterMutex(stream, connection->shutdown));
}
}
return error;
}
size_t Buffer::post(void *buf, timeout_t timeout)
{
size_t rc;
if(!timeout)
timeout = INFINITE;
if(Thread::waitThread(sem_tail, timeout) != WAIT_OBJECT_0)
return Buffer::timeout;
enterMutex();
rc = onPost(buf);
++_used;
leaveMutex();
::ReleaseSemaphore(sem_head, 1, (LPLONG)NULL);
return rc;
}
void *MapTable::getObject(const char *id)
{
if(!map)
return NULL;
enterMutex();
MapObject *obj = map[getIndex(id)];
leaveMutex();
while(obj)
{
if(!stricmp(obj->idObject, id))
break;
obj = obj->nextObject;
}
return (void *)obj;
}
/*
* Enter/exit with stream mutex held.
* On error, does not hold the stream mutex.
*/
static jint
waitForSpace(SharedMemoryConnection *connection, Stream *stream)
{
jint error = SYS_OK;
/* Assumes mutex is held on call */
while ((error == SYS_OK) && FULL(stream)) {
CHECK_ERROR(leaveMutex(stream));
error = sysEventWait(connection->otherProcess, stream->hasSpace, 0);
if (error == SYS_OK) {
CHECK_ERROR(enterMutex(stream, connection->shutdown));
} else {
setLastError(error);
}
}
return error;
}
/* enter the stream's mutex and (optionally) check for a closed stream */
static jint
enterMutex(Stream *stream, sys_event_t event)
{
jint ret = sysIPMutexEnter(stream->mutex, event);
if (ret != SYS_OK) {
if (IS_STATE_CLOSED(stream->state)) {
setLastErrorMsg("stream closed");
}
return ret;
}
if (IS_STATE_CLOSED(stream->state)) {
setLastErrorMsg("stream closed");
(void)leaveMutex(stream);
return SYS_ERR;
}
return SYS_OK;
}
/*
** Register an unlock-notify callback.
**
** This is called after connection "db" has attempted some operation
** but has received an SQLITE_LOCKED error because another connection
** (call it pOther) in the same process was busy using the same shared
** cache. pOther is found by looking at db->pBlockingConnection.
**
** If there is no blocking connection, the callback is invoked immediately,
** before this routine returns.
**
** If pOther is already blocked on db, then report SQLITE_LOCKED, to indicate
** a deadlock.
**
** Otherwise, make arrangements to invoke xNotify when pOther drops
** its locks.
**
** Each call to this routine overrides any prior callbacks registered
** on the same "db". If xNotify==0 then any prior callbacks are immediately
** cancelled.
*/
int sqlite3_unlock_notify(
sqlite3 *db,
void (*xNotify)(void **, int),
void *pArg
){
int rc = SQLITE_OK;
sqlite3_mutex_enter(db->mutex);
enterMutex();
if( xNotify==0 ){
removeFromBlockedList(db);
db->pBlockingConnection = 0;
db->pUnlockConnection = 0;
db->xUnlockNotify = 0;
db->pUnlockArg = 0;
}else if( 0==db->pBlockingConnection ){
/* The blocking transaction has been concluded. Or there never was a
** blocking transaction. In either case, invoke the notify callback
** immediately.
*/
xNotify(&pArg, 1);
}else{
sqlite3 *p;
for(p=db->pBlockingConnection; p && p!=db; p=p->pUnlockConnection){}
if( p ){
rc = SQLITE_LOCKED; /* Deadlock detected. */
}else{
db->pUnlockConnection = db->pBlockingConnection;
db->xUnlockNotify = xNotify;
db->pUnlockArg = pArg;
removeFromBlockedList(db);
addToBlockedList(db);
}
}
leaveMutex();
assert( !db->mallocFailed );
sqlite3ErrorWithMsg(db, rc, (rc?"database is deadlocked":0));
sqlite3_mutex_leave(db->mutex);
return rc;
}
void ThreadQueue::post(const void *dp, unsigned len)
{
data_t *data = (data_t *)new char[sizeof(data_t) + len];
memcpy(data->data, dp, len);
data->len = len;
data->next = NULL;
enterMutex();
if(!first)
first = data;
if(last)
last->next = data;
last = data;
if(!started)
{
start();
started = true;
}
leaveMutex();
Semaphore::post();
}
static jint
closeStream(Stream *stream)
{
/*
* Lock stream during close - ignore shutdown event as we are
* closing down and shutdown should be signalled.
*/
CHECK_ERROR(enterMutex(stream, NULL));
/* mark the stream as closed */
stream->state = STATE_CLOSED;
/* wake up waitForData() if it is in sysEventWait() */
sysEventSignal(stream->hasData);
sysEventClose(stream->hasData);
/* wake up waitForSpace() if it is in sysEventWait() */
sysEventSignal(stream->hasSpace);
sysEventClose(stream->hasSpace);
CHECK_ERROR(leaveMutex(stream));
sysIPMutexClose(stream->mutex);
return SYS_OK;
}
static jint
sendBytes(SharedMemoryConnection *connection, const void *bytes, jint length)
{
Stream *stream = &connection->outgoing;
SharedStream *shared = stream->shared;
jint fragmentStart;
jint fragmentLength;
jint index = 0;
jint maxLength;
clearLastError();
CHECK_ERROR(enterMutex(stream, connection->shutdown));
while (index < length) {
CHECK_ERROR(waitForSpace(connection, stream));
SHMEM_ASSERT(!FULL(stream));
fragmentStart = shared->writeOffset;
if (fragmentStart < shared->readOffset) {
maxLength = shared->readOffset - fragmentStart;
} else {
maxLength = SHARED_BUFFER_SIZE - fragmentStart;
}
fragmentLength = MIN(maxLength, length - index);
memcpy(shared->buffer + fragmentStart, (jbyte *)bytes + index, fragmentLength);
shared->writeOffset = ADD_OFFSET(fragmentStart, fragmentLength);
index += fragmentLength;
shared->isFull = (shared->readOffset == shared->writeOffset);
STREAM_INVARIANT(stream);
CHECK_ERROR(signalData(stream));
}
CHECK_ERROR(leaveMutex(stream));
return SYS_OK;
}
jint
shmemBase_receiveByte(SharedMemoryConnection *connection, jbyte *data)
{
Stream *stream = &connection->incoming;
SharedStream *shared = stream->shared;
int offset;
CHECK_ERROR(enterMutex(stream, connection->shutdown));
CHECK_ERROR(waitForData(connection, stream));
SHMEM_ASSERT(!EMPTY(stream));
offset = shared->readOffset;
*data = shared->buffer[offset];
shared->readOffset = ADD_OFFSET(offset, 1);
shared->isFull = JNI_FALSE;
STREAM_INVARIANT(stream);
CHECK_ERROR(leaveMutex(stream));
CHECK_ERROR(signalSpace(stream));
return SYS_OK;
}
jint
shmemBase_sendByte(SharedMemoryConnection *connection, jbyte data)
{
Stream *stream = &connection->outgoing;
SharedStream *shared = stream->shared;
int offset;
CHECK_ERROR(enterMutex(stream, connection->shutdown));
CHECK_ERROR(waitForSpace(connection, stream));
SHMEM_ASSERT(!FULL(stream));
offset = shared->writeOffset;
shared->buffer[offset] = data;
shared->writeOffset = ADD_OFFSET(offset, 1);
shared->isFull = (shared->readOffset == shared->writeOffset);
STREAM_INVARIANT(stream);
CHECK_ERROR(leaveMutex(stream));
CHECK_ERROR(signalData(stream));
return SYS_OK;
}
void SocketService::detach(SocketPort *port)
{
enterMutex();
#if !defined(USE_POLL)
FD_CLR(port->so, &connect);
#endif
if(port->prev) {
port->prev->next = port->next;
} else {
first = port->next;
}
if(port->next) {
port->next->prev = port->prev;
} else {
last = port->prev;
}
port->service = NULL;
--count;
leaveMutex();
update();
}
void SocketService::run(void)
{
timeout_t timer, expires;
SocketPort *port;
unsigned char buf;
#ifndef WIN32
#ifdef USE_POLL
Poller mfd;
pollfd * p_ufd;
int lastcount = 0;
// initialize ufd in all attached ports :
// probably don't need this but it can't hurt.
enterMutex();
port = first;
while(port) {
port->ufd = 0;
port = port->next;
}
leaveMutex();
#else
struct timeval timeout, *tvp;
fd_set inp, out, err;
FD_ZERO(&inp);
FD_ZERO(&out);
FD_ZERO(&err);
int so;
#endif
#else // WIN32
int numHandle = 0;
HANDLE hv[MAXIMUM_WAIT_OBJECTS];
#endif
#ifdef WIN32
// FIXME: needed ?
ResetEvent(sync->GetSync());
#endif
setCancel(cancelDeferred);
for(;;) {
timer = TIMEOUT_INF;
#ifndef WIN32
while(1 == ::read(iosync[0], (char *)&buf, 1)) {
#else
for(;;) {
int f = sync->getFlag();
if (f < 0)
break;
buf = f;
#endif
if(buf) {
onUpdate(buf);
continue;
}
setCancel(cancelImmediate);
sleep(TIMEOUT_INF);
exit();
}
#ifndef WIN32
#ifdef USE_POLL
bool reallocate = false;
MUTEX_START
onEvent();
port = first;
while(port) {
onCallback(port);
if ( ( p_ufd = port->ufd ) ) {
if ( ( POLLHUP | POLLNVAL ) & p_ufd->revents ) {
// Avoid infinite loop from disconnected sockets
port->detect_disconnect = false;
p_ufd->events &= ~POLLHUP;
SocketPort* p = port;
port = port->next;
detach(p);
reallocate = true;
p->disconnect();
continue;
}
if ( ( POLLIN | POLLPRI ) & p_ufd->revents )
port->pending();
if ( POLLOUT & p_ufd->revents )
port->output();
} else {
reallocate = true;
}
retry:
expires = port->getTimer();
if(expires > 0)
if(expires < timer)
timer = expires;
if(!expires) {
port->endTimer();
port->expired();
goto retry;
}
port = port->next;
}
//
// reallocate things if we saw a ServerPort without
// ufd set !
if ( reallocate || ( ( count + 1 ) != lastcount ) ) {
lastcount = count + 1;
p_ufd = mfd.getList( count + 1 );
// Set up iosync polling
p_ufd->fd = iosync[0];
p_ufd->events = POLLIN | POLLHUP;
p_ufd ++;
port = first;
while(port) {
p_ufd->fd = port->so;
p_ufd->events =
( port->detect_disconnect ? POLLHUP : 0 )
| ( port->detect_output ? POLLOUT : 0 )
| ( port->detect_pending ? POLLIN : 0 )
;
port->ufd = p_ufd;
p_ufd ++;
port = port->next;
}
}
MUTEX_END
poll( mfd.getList(), lastcount, timer );
#else
MUTEX_START
onEvent();
port = first;
while(port) {
onCallback(port);
so = port->so;
if(FD_ISSET(so, &err)) {
port->detect_disconnect = false;
SocketPort* p = port;
port = port->next;
p->disconnect();
continue;
}
if(FD_ISSET(so, &inp))
port->pending();
if(FD_ISSET(so, &out))
port->output();
retry:
expires = port->getTimer();
if(expires > 0)
if(expires < timer)
timer = expires;
// if we expire, get new scheduling now
if(!expires) {
port->endTimer();
port->expired();
goto retry;
}
port = port->next;
}
FD_ZERO(&inp);
FD_ZERO(&out);
FD_ZERO(&err);
FD_SET(iosync[0],&inp);
port = first;
while(port) {
so = port->so;
if(port->detect_pending)
FD_SET(so, &inp);
if(port->detect_output)
FD_SET(so, &out);
if(port->detect_disconnect)
FD_SET(so, &err);
port = port->next;
}
MUTEX_END
if(timer == TIMEOUT_INF)
tvp = NULL;
else {
tvp = &timeout;
timeout.tv_sec = timer / 1000;
timeout.tv_usec = (timer % 1000) * 1000;
}
select(hiwater, &inp, &out, &err, tvp);
#endif
#else // WIN32
MUTEX_START
onEvent();
hv[0] = sync->GetSync();
numHandle = 1;
port = first;
while(port) {
onCallback(port);
long events = 0;
if(port->detect_pending)
events |= FD_READ;
if(port->detect_output)
events |= FD_WRITE;
if(port->detect_disconnect)
events |= FD_CLOSE;
// !!! ignore some socket on overflow !!!
if (events && numHandle < MAXIMUM_WAIT_OBJECTS) {
WSAEventSelect(port->so,port->event,events);
hv[numHandle++] = port->event;
}
retry:
expires = port->getTimer();
if(expires > 0)
if(expires < timer)
timer = expires;
// if we expire, get new scheduling now
if(!expires) {
port->endTimer();
port->expired();
goto retry;
}
port = port->next;
}
MUTEX_END
// FIXME: handle thread cancellation correctly
DWORD res = WaitForMultipleObjects(numHandle,hv,FALSE,timer);
switch (res) {
case WAIT_OBJECT_0:
break;
case WAIT_TIMEOUT:
break;
default:
// FIXME: handle failures (detach SocketPort)
if (res >= WAIT_OBJECT_0+1 && res <= WAIT_OBJECT_0+MAXIMUM_WAIT_OBJECTS) {
int curr = res - (WAIT_OBJECT_0);
WSANETWORKEVENTS events;
// search port
MUTEX_START
port = first;
while(port) {
if (port->event == hv[curr])
break;
port = port->next;
}
MUTEX_END
// if port not found ignore
if (!port || port->event != hv[curr])
break;
WSAEnumNetworkEvents(port->so,port->event,&events);
if(events.lNetworkEvents & FD_CLOSE) {
port->detect_disconnect = false;
port->disconnect();
continue;
}
if(events.lNetworkEvents & FD_READ)
port->pending();
if(events.lNetworkEvents & FD_WRITE)
port->output();
}
}
#endif
}
}
void SocketService::run(void)
{
timeout_t timer, expires;
SocketPort *port;
unsigned char buf;
#ifdef USE_POLL
Poller mfd;
pollfd * p_ufd;
int lastcount = 0;
// initialize ufd in all attached ports :
// probably don't need this but it can't hurt.
enterMutex();
port = first;
while(port)
{
port->ufd = 0;
port = port->next;
}
leaveMutex();
#else
struct timeval timeout, *tvp;
fd_set inp, out, err;
FD_ZERO(&inp);
FD_ZERO(&out);
FD_ZERO(&err);
int so;
#endif
setCancel(cancelDeferred);
for(;;)
{
timer = TIMEOUT_INF;
while(1 == ::read(iosync[0], (char *)&buf, 1))
{
if(buf)
{
onUpdate(buf);
continue;
}
setCancel(cancelImmediate);
sleep(TIMEOUT_INF);
exit();
}
#ifdef USE_POLL
bool reallocate = false;
MUTEX_START
onEvent();
port = first;
while(port)
{
onCallback(port);
if ( ( p_ufd = port->ufd ) ) {
if ( ( POLLHUP | POLLNVAL ) & p_ufd->revents ) {
// Avoid infinite loop from disconnected sockets
port->detect_disconnect = false;
p_ufd->events &= ~POLLHUP;
SocketPort* p = port;
port = port->next;
detach(p);
reallocate = true;
p->disconnect();
continue;
}
if ( ( POLLIN | POLLPRI ) & p_ufd->revents )
port->pending();
if ( POLLOUT & p_ufd->revents )
port->output();
} else {
reallocate = true;
}
retry:
expires = port->getTimer();
if(expires > 0)
if(expires < timer)
timer = expires;
if(!expires)
{
port->endTimer();
port->expired();
goto retry;
}
port = port->next;
}
//
// reallocate things if we saw a ServerPort without
// ufd set !
if ( reallocate || ( ( count + 1 ) != lastcount ) ) {
lastcount = count + 1;
p_ufd = mfd.getList( count + 1 );
// Set up iosync polling
p_ufd->fd = iosync[0];
p_ufd->events = POLLIN | POLLHUP;
p_ufd ++;
port = first;
while(port)
{
p_ufd->fd = port->so;
p_ufd->events =
( port->detect_disconnect ? POLLHUP : 0 )
| ( port->detect_output ? POLLOUT : 0 )
| ( port->detect_pending ? POLLIN : 0 )
;
port->ufd = p_ufd;
p_ufd ++;
port = port->next;
}
}
MUTEX_END
poll( mfd.getList(), lastcount, timer );
#else
MUTEX_START
onEvent();
port = first;
while(port)
{
onCallback(port);
so = port->so;
if(FD_ISSET(so, &err)) {
port->detect_disconnect = false;
SocketPort* p = port;
port = port->next;
p->disconnect();
continue;
}
if(FD_ISSET(so, &inp))
port->pending();
if(FD_ISSET(so, &out))
port->output();
retry:
expires = port->getTimer();
if(expires > 0)
if(expires < timer)
timer = expires;
// if we expire, get new scheduling now
if(!expires)
{
port->endTimer();
port->expired();
goto retry;
}
port = port->next;
}
FD_ZERO(&inp);
FD_ZERO(&out);
FD_ZERO(&err);
FD_SET(iosync[0],&inp);
port = first;
while(port)
{
so = port->so;
if(port->detect_pending)
FD_SET(so, &inp);
if(port->detect_output)
FD_SET(so, &out);
if(port->detect_disconnect)
FD_SET(so, &err);
port = port->next;
}
MUTEX_END
if(timer == TIMEOUT_INF)
tvp = NULL;
else
{
tvp = &timeout;
timeout.tv_sec = timer / 1000;
timeout.tv_usec = (timer % 1000) * 1000;
}
select(hiwater, &inp, &out, &err, tvp);
#endif
}
}
void SharedMemPager::purge(void)
{
enterMutex();
MemPager::purge();
leaveMutex();
}
/*
** This function is called when
** the transaction opened by database db has just finished. Locks held
** by database connection db have been released.
**
** This function loops through each entry in the blocked connections
** list and does the following:
**
** 1) If the sqlite3.pBlockingConnection member of a list entry is
** set to db, then set pBlockingConnection=0.
**
** 2) If the sqlite3.pUnlockConnection member of a list entry is
** set to db, then invoke the configured unlock-notify callback and
** set pUnlockConnection=0.
**
** 3) If the two steps above mean that pBlockingConnection==0 and
** pUnlockConnection==0, remove the entry from the blocked connections
** list.
*/
void sqlite3ConnectionUnlocked(sqlite3 *db){
void (*xUnlockNotify)(void **, int) = 0; /* Unlock-notify cb to invoke */
int nArg = 0; /* Number of entries in aArg[] */
sqlite3 **pp; /* Iterator variable */
void **aArg; /* Arguments to the unlock callback */
void **aDyn = 0; /* Dynamically allocated space for aArg[] */
void *aStatic[16]; /* Starter space for aArg[]. No malloc required */
aArg = aStatic;
enterMutex(); /* Enter STATIC_MASTER mutex */
/* This loop runs once for each entry in the blocked-connections list. */
for(pp=&sqlite3BlockedList; *pp; /* no-op */ ){
sqlite3 *p = *pp;
/* Step 1. */
if( p->pBlockingConnection==db ){
p->pBlockingConnection = 0;
}
/* Step 2. */
if( p->pUnlockConnection==db ){
assert( p->xUnlockNotify );
if( p->xUnlockNotify!=xUnlockNotify && nArg!=0 ){
xUnlockNotify(aArg, nArg);
nArg = 0;
}
sqlite3BeginBenignMalloc();
assert( aArg==aDyn || (aDyn==0 && aArg==aStatic) );
assert( nArg<=(int)ArraySize(aStatic) || aArg==aDyn );
if( (!aDyn && nArg==(int)ArraySize(aStatic))
|| (aDyn && nArg==(int)(sqlite3MallocSize(aDyn)/sizeof(void*)))
){
/* The aArg[] array needs to grow. */
void **pNew = (void **)sqlite3Malloc(nArg*sizeof(void *)*2);
if( pNew ){
memcpy(pNew, aArg, nArg*sizeof(void *));
sqlite3_free(aDyn);
aDyn = aArg = pNew;
}else{
/* This occurs when the array of context pointers that need to
** be passed to the unlock-notify callback is larger than the
** aStatic[] array allocated on the stack and the attempt to
** allocate a larger array from the heap has failed.
**
** This is a difficult situation to handle. Returning an error
** code to the caller is insufficient, as even if an error code
** is returned the transaction on connection db will still be
** closed and the unlock-notify callbacks on blocked connections
** will go unissued. This might cause the application to wait
** indefinitely for an unlock-notify callback that will never
** arrive.
**
** Instead, invoke the unlock-notify callback with the context
** array already accumulated. We can then clear the array and
** begin accumulating any further context pointers without
** requiring any dynamic allocation. This is sub-optimal because
** it means that instead of one callback with a large array of
** context pointers the application will receive two or more
** callbacks with smaller arrays of context pointers, which will
** reduce the applications ability to prioritize multiple
** connections. But it is the best that can be done under the
** circumstances.
*/
xUnlockNotify(aArg, nArg);
nArg = 0;
}
}
sqlite3EndBenignMalloc();
aArg[nArg++] = p->pUnlockArg;
xUnlockNotify = p->xUnlockNotify;
p->pUnlockConnection = 0;
p->xUnlockNotify = 0;
p->pUnlockArg = 0;
}
/* Step 3. */
if( p->pBlockingConnection==0 && p->pUnlockConnection==0 ){
/* Remove connection p from the blocked connections list. */
*pp = p->pNextBlocked;
p->pNextBlocked = 0;
}else{
pp = &p->pNextBlocked;
}
}
if( nArg!=0 ){
xUnlockNotify(aArg, nArg);
}
sqlite3_free(aDyn);
leaveMutex(); /* Leave STATIC_MASTER mutex */
}