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Allow the database file to be memory mapped in wal mode.

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FossilOrigin-Name: d190ddabc386bc9654b99e33fb81b2f6e67b54d6
This commit is contained in:
dan
2013-03-22 18:20:14 +00:00
parent c00033125d
commit 99bd10979a
6 changed files with 124 additions and 62 deletions
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67
src/wal.c
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@@ -412,6 +412,7 @@ struct Wal {
sqlite3_vfs *pVfs; /* The VFS used to create pDbFd */
sqlite3_file *pDbFd; /* File handle for the database file */
sqlite3_file *pWalFd; /* File handle for WAL file */
Pager *pPager; /* Pager object */
u32 iCallback; /* Value to pass to log callback (or 0) */
i64 mxWalSize; /* Truncate WAL to this size upon reset */
int nWiData; /* Size of array apWiData */
@@ -1251,6 +1252,7 @@ static void walIndexClose(Wal *pWal, int isDelete){
*/
int sqlite3WalOpen(
sqlite3_vfs *pVfs, /* vfs module to open wal and wal-index */
Pager *pPager, /* Pager object handle */
sqlite3_file *pDbFd, /* The open database file */
const char *zWalName, /* Name of the WAL file */
int bNoShm, /* True to run in heap-memory mode */
@@ -1291,6 +1293,7 @@ int sqlite3WalOpen(
pRet->zWalName = zWalName;
pRet->syncHeader = 1;
pRet->padToSectorBoundary = 1;
pRet->pPager = pPager;
pRet->exclusiveMode = (bNoShm ? WAL_HEAPMEMORY_MODE: WAL_NORMAL_MODE);
/* Open file handle on the write-ahead log file. */
@@ -1727,10 +1730,7 @@ static int walCheckpoint(
*/
if( rc==SQLITE_OK ){
i64 nReq = ((i64)mxPage * szPage);
rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
if( rc==SQLITE_OK && nSize<nReq ){
sqlite3OsFileControlHint(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
}
rc = sqlite3PagerSetFilesize(pWal->pPager, nReq);
}
/* Iterate through the contents of the WAL, copying data to the db file. */
@@ -1744,7 +1744,7 @@ static int walCheckpoint(
if( rc!=SQLITE_OK ) break;
iOffset = (iDbpage-1)*(i64)szPage;
testcase( IS_BIG_INT(iOffset) );
rc = sqlite3OsWrite(pWal->pDbFd, zBuf, szPage, iOffset);
rc = sqlite3PagerWriteData(pWal->pPager, zBuf, szPage, iOffset);
if( rc!=SQLITE_OK ) break;
}
@@ -2287,19 +2287,17 @@ void sqlite3WalEndReadTransaction(Wal *pWal){
}
/*
** Read a page from the WAL, if it is present in the WAL and if the
** current read transaction is configured to use the WAL.
** Search the wal file for page pgno. If found, set *piRead to the frame that
** contains the page. Otherwise, if pgno is not in the wal file, set *piRead
** to zero.
**
** The *pInWal is set to 1 if the requested page is in the WAL and
** has been loaded. Or *pInWal is set to 0 if the page was not in
** the WAL and needs to be read out of the database.
** Return SQLITE_OK if successful, or an error code if an error occurs. If an
** error does occur, the final value of *piRead is undefined.
*/
int sqlite3WalRead(
int sqlite3WalFindFrame(
Wal *pWal, /* WAL handle */
Pgno pgno, /* Database page number to read data for */
int *pInWal, /* OUT: True if data is read from WAL */
int nOut, /* Size of buffer pOut in bytes */
u8 *pOut /* Buffer to write page data to */
u32 *piRead /* OUT: Frame number (or zero) */
){
u32 iRead = 0; /* If !=0, WAL frame to return data from */
u32 iLast = pWal->hdr.mxFrame; /* Last page in WAL for this reader */
@@ -2315,7 +2313,7 @@ int sqlite3WalRead(
** WAL were empty.
*/
if( iLast==0 || pWal->readLock==0 ){
*pInWal = 0;
*piRead = 0;
return SQLITE_OK;
}
@@ -2386,26 +2384,31 @@ int sqlite3WalRead(
}
#endif
/* If iRead is non-zero, then it is the log frame number that contains the
** required page. Read and return data from the log file.
*/
if( iRead ){
int sz;
i64 iOffset;
sz = pWal->hdr.szPage;
sz = (sz&0xfe00) + ((sz&0x0001)<<16);
testcase( sz<=32768 );
testcase( sz>=65536 );
iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;
*pInWal = 1;
/* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
return sqlite3OsRead(pWal->pWalFd, pOut, (nOut>sz ? sz : nOut), iOffset);
}
*pInWal = 0;
*piRead = iRead;
return SQLITE_OK;
}
/*
** Read the contents of frame iRead from the wal file into buffer pOut
** (which is nOut bytes in size). Return SQLITE_OK if successful, or an
** error code otherwise.
*/
int sqlite3WalReadFrame(
Wal *pWal, /* WAL handle */
u32 iRead, /* Frame to read */
int nOut, /* Size of buffer pOut in bytes */
u8 *pOut /* Buffer to write page data to */
){
int sz;
i64 iOffset;
sz = pWal->hdr.szPage;
sz = (sz&0xfe00) + ((sz&0x0001)<<16);
testcase( sz<=32768 );
testcase( sz>=65536 );
iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;
/* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
return sqlite3OsRead(pWal->pWalFd, pOut, (nOut>sz ? sz : nOut), iOffset);
}
/*
** Return the size of the database in pages (or zero, if unknown).