GDALDataset* GDALProxyPoolDataset::RefUnderlyingDataset()
{
/* We pretend that the current thread is responsiblePID, that is */
/* to say the thread that created that GDALProxyPoolDataset object. */
/* This is for the case when a GDALProxyPoolDataset is created by a */
/* thread and used by other threads. These other threads, when doing actual */
/* IO, will come there and potentially open the underlying dataset. */
/* By doing this, they can indirectly call GDALOpenShared() on .aux file */
/* for example. So this call to GDALOpenShared() must occur as if it */
/* was done by the creating thread, otherwise it will not be correctly closed afterwards... */
/* To make a long story short : this is necessary when warping with ChunkAndWarpMulti */
/* a VRT of GeoTIFFs that have associated .aux files */
GIntBig curResponsiblePID = GDALGetResponsiblePIDForCurrentThread();
GDALSetResponsiblePIDForCurrentThread(responsiblePID);
cacheEntry = GDALDatasetPool::RefDataset(GetDescription(), eAccess);
GDALSetResponsiblePIDForCurrentThread(curResponsiblePID);
if (cacheEntry != NULL)
{
if (cacheEntry->poDS != NULL)
return cacheEntry->poDS;
else
GDALDatasetPool::UnrefDataset(cacheEntry);
}
return NULL;
}
void GDALDatasetPool::_CloseDataset(const char* pszFileName, GDALAccess eAccess)
{
GDALProxyPoolCacheEntry* cur = firstEntry;
GIntBig responsiblePID = GDALGetResponsiblePIDForCurrentThread();
while(cur)
{
GDALProxyPoolCacheEntry* next = cur->next;
CPLAssert(cur->pszFileName);
if (strcmp(cur->pszFileName, pszFileName) == 0 && cur->refCount == 0 &&
cur->poDS != NULL )
{
/* Close by pretending we are the thread that GDALOpen'ed this */
/* dataset */
GDALSetResponsiblePIDForCurrentThread(cur->responsiblePID);
refCountOfDisableRefCount ++;
GDALClose(cur->poDS);
refCountOfDisableRefCount --;
GDALSetResponsiblePIDForCurrentThread(responsiblePID);
cur->poDS = NULL;
cur->pszFileName[0] = '\0';
break;
}
cur = next;
}
}
GDALDatasetPool::~GDALDatasetPool()
{
GDALProxyPoolCacheEntry* cur = firstEntry;
GIntBig responsiblePID = GDALGetResponsiblePIDForCurrentThread();
while(cur)
{
GDALProxyPoolCacheEntry* next = cur->next;
CPLFree(cur->pszFileName);
CPLAssert(cur->refCount == 0);
if (cur->poDS)
{
GDALSetResponsiblePIDForCurrentThread(cur->responsiblePID);
GDALClose(cur->poDS);
}
CPLFree(cur);
cur = next;
}
GDALSetResponsiblePIDForCurrentThread(responsiblePID);
}
GDALProxyPoolCacheEntry* GDALDatasetPool::_RefDataset(const char* pszFileName, GDALAccess eAccess)
{
GDALProxyPoolCacheEntry* cur = firstEntry;
GIntBig responsiblePID = GDALGetResponsiblePIDForCurrentThread();
GDALProxyPoolCacheEntry* lastEntryWithZeroRefCount = NULL;
while(cur)
{
GDALProxyPoolCacheEntry* next = cur->next;
if (strcmp(cur->pszFileName, pszFileName) == 0 &&
cur->responsiblePID == responsiblePID)
{
if (cur != firstEntry)
{
/* Move to begin */
if (cur->next)
cur->next->prev = cur->prev;
else
lastEntry = cur->prev;
cur->prev->next = cur->next;
cur->prev = NULL;
firstEntry->prev = cur;
cur->next = firstEntry;
firstEntry = cur;
#ifdef DEBUG_PROXY_POOL
CheckLinks();
#endif
}
cur->refCount ++;
return cur;
}
if (cur->refCount == 0)
lastEntryWithZeroRefCount = cur;
cur = next;
}
if (currentSize == maxSize)
{
if (lastEntryWithZeroRefCount == NULL)
{
CPLError(CE_Failure, CPLE_AppDefined,
"Too many threads are running for the current value of the dataset pool size (%d).\n"
"or too many proxy datasets are opened in a cascaded way.\n"
"Try increasing GDAL_MAX_DATASET_POOL_SIZE.", maxSize);
return NULL;
}
CPLFree(lastEntryWithZeroRefCount->pszFileName);
lastEntryWithZeroRefCount->pszFileName = NULL;
if (lastEntryWithZeroRefCount->poDS)
{
/* Close by pretending we are the thread that GDALOpen'ed this */
/* dataset */
GDALSetResponsiblePIDForCurrentThread(lastEntryWithZeroRefCount->responsiblePID);
refCountOfDisableRefCount ++;
GDALClose(lastEntryWithZeroRefCount->poDS);
refCountOfDisableRefCount --;
lastEntryWithZeroRefCount->poDS = NULL;
GDALSetResponsiblePIDForCurrentThread(responsiblePID);
}
/* Recycle this entry for the to-be-openeded dataset and */
/* moves it to the top of the list */
if (lastEntryWithZeroRefCount->prev)
lastEntryWithZeroRefCount->prev->next = lastEntryWithZeroRefCount->next;
else {
CPLAssert(0);
}
if (lastEntryWithZeroRefCount->next)
lastEntryWithZeroRefCount->next->prev = lastEntryWithZeroRefCount->prev;
else
{
CPLAssert(lastEntryWithZeroRefCount == lastEntry);
lastEntry->prev->next = NULL;
lastEntry = lastEntry->prev;
}
lastEntryWithZeroRefCount->prev = NULL;
lastEntryWithZeroRefCount->next = firstEntry;
firstEntry->prev = lastEntryWithZeroRefCount;
cur = firstEntry = lastEntryWithZeroRefCount;
#ifdef DEBUG_PROXY_POOL
CheckLinks();
#endif
}
else
{
/* Prepend */
cur = (GDALProxyPoolCacheEntry*) CPLMalloc(sizeof(GDALProxyPoolCacheEntry));
if (lastEntry == NULL)
lastEntry = cur;
cur->prev = NULL;
cur->next = firstEntry;
if (firstEntry)
firstEntry->prev = cur;
firstEntry = cur;
currentSize ++;
#ifdef DEBUG_PROXY_POOL
CheckLinks();
#endif
}
cur->pszFileName = CPLStrdup(pszFileName);
cur->responsiblePID = responsiblePID;
cur->refCount = 1;
refCountOfDisableRefCount ++;
cur->poDS = (GDALDataset*) GDALOpen(pszFileName, eAccess);
refCountOfDisableRefCount --;
return cur;
}
