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Improvements to the memdb VFS.

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FossilOrigin-Name: a14fed69d0d4932fc6c71cf8acc5199cca4efbd10bca563a8e86038d6afd5c64
This commit is contained in:
drh
2018-03-06 04:01:08 +00:00
parent bcdb28dff3
commit 5f9d192de9
3 changed files with 33 additions and 19 deletions
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38
src/memdb.c
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@@ -53,7 +53,7 @@ static int memdbFileSize(sqlite3_file*, sqlite3_int64 *pSize);
static int memdbLock(sqlite3_file*, int);
static int memdbCheckReservedLock(sqlite3_file*, int *pResOut);
static int memdbFileControl(sqlite3_file*, int op, void *pArg);
static int memdbSectorSize(sqlite3_file*);
/* static int memdbSectorSize(sqlite3_file*); // not used */
static int memdbDeviceCharacteristics(sqlite3_file*);
static int memdbFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
static int memdbUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p);
@@ -109,7 +109,7 @@ static const sqlite3_io_methods memdb_io_methods = {
memdbLock, /* xUnlock - same as xLock in this case */
memdbCheckReservedLock, /* xCheckReservedLock */
memdbFileControl, /* xFileControl */
memdbSectorSize, /* xSectorSize */
0, /* memdbSectorSize,*/ /* xSectorSize */
memdbDeviceCharacteristics, /* xDeviceCharacteristics */
0, /* xShmMap */
0, /* xShmLock */
@@ -157,10 +157,11 @@ static int memdbRead(
*/
static int memdbEnlarge(MemFile *p, sqlite3_int64 newSz){
unsigned char *pNew;
if( (p->mFlags & SQLITE_DESERIALIZE_RESIZEABLE)==0 ) return SQLITE_FULL;
if( p->nMmap>0 ) return SQLITE_FULL;
if( (p->mFlags & SQLITE_DESERIALIZE_RESIZEABLE)==0 || p->nMmap>0 ){
return SQLITE_FULL;
}
pNew = sqlite3_realloc64(p->aData, newSz);
if( pNew==0 ) return SQLITE_FULL;
if( pNew==0 ) return SQLITE_NOMEM;
p->aData = pNew;
p->szMax = newSz;
return SQLITE_OK;
@@ -177,8 +178,11 @@ static int memdbWrite(
){
MemFile *p = (MemFile *)pFile;
if( iOfst+iAmt>p->sz ){
if( iOfst+iAmt>p->szMax && memdbEnlarge(p, (iOfst+iAmt)*2) ){
return SQLITE_FULL;
int rc;
if( iOfst+iAmt>p->szMax
&& (rc = memdbEnlarge(p, (iOfst+iAmt)*2))!=SQLITE_OK
){
return rc;
}
if( iOfst>p->sz ) memset(p->aData+p->sz, 0, iOfst-p->sz);
p->sz = iOfst+iAmt;
@@ -193,7 +197,10 @@ static int memdbWrite(
static int memdbTruncate(sqlite3_file *pFile, sqlite_int64 size){
MemFile *p = (MemFile *)pFile;
if( size>p->sz ){
if( size>p->szMax && memdbEnlarge(p, size) ) return SQLITE_FULL;
int rc;
if( size>p->szMax && (rc = memdbEnlarge(p, size))!=SQLITE_OK ){
return rc;
}
memset(p->aData+p->sz, 0, size-p->sz);
}
p->sz = size;
@@ -246,12 +253,14 @@ static int memdbFileControl(sqlite3_file *pFile, int op, void *pArg){
return rc;
}
#if 0 /* Not used because of SQLITE_IOCAP_POWERSAFE_OVERWRITE */
/*
** Return the sector-size in bytes for an memdb-file.
*/
static int memdbSectorSize(sqlite3_file *pFile){
return 1024;
}
#endif
/*
** Return the device characteristic flags supported by an memdb-file.
@@ -294,10 +303,12 @@ static int memdbOpen(
int *pOutFlags
){
MemFile *p = (MemFile*)pFile;
if( (flags & SQLITE_OPEN_MAIN_DB)==0 ){
return ORIGVFS(pVfs)->xOpen(ORIGVFS(pVfs), zName, pFile, flags, pOutFlags);
}
memset(p, 0, sizeof(*p));
if( (flags & SQLITE_OPEN_MAIN_DB)==0 ) return SQLITE_CANTOPEN;
p->mFlags = SQLITE_DESERIALIZE_RESIZEABLE | SQLITE_DESERIALIZE_FREEONCLOSE;
*pOutFlags = flags | SQLITE_OPEN_MEMORY;
if( pOutFlags ) *pOutFlags = flags | SQLITE_OPEN_MEMORY;
p->base.pMethods = &memdb_io_methods;
return SQLITE_OK;
}
@@ -537,8 +548,11 @@ end_deserialize:
** Register the new VFS.
*/
int sqlite3MemdbInit(void){
memdb_vfs.pAppData = sqlite3_vfs_find(0);
memdb_vfs.szOsFile = sizeof(MemFile);
sqlite3_vfs *pLower = sqlite3_vfs_find(0);
int sz = pLower->szOsFile;
memdb_vfs.pAppData = pLower;
if( sz<sizeof(MemFile) ) sz = sizeof(MemFile);
memdb_vfs.szOsFile = sz;
return sqlite3_vfs_register(&memdb_vfs, 0);
}
#endif /* SQLITE_ENABLE_MEMDB */