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When possible, use memcpy() to and from the mapped region instead of xWrite() and xRead().

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FossilOrigin-Name: f8ca5622d99bedca957caa9ad311d798f63b3ce9
This commit is contained in:
dan
2013-03-16 20:19:21 +00:00
parent 7af6547a5a
commit a72014faf5
4 changed files with 65 additions and 16 deletions
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41
src/pager.c
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@@ -2865,9 +2865,13 @@ static int readDbPage(PgHdr *pPg){
}
if( rc==SQLITE_OK && !isInWal ){
i64 iOffset = (pgno-1)*(i64)pPager->pageSize;
rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
if( rc==SQLITE_IOERR_SHORT_READ ){
rc = SQLITE_OK;
if( pPager->pMap && pPager->nMapValid>=iOffset+pPager->pageSize ){
memcpy(pPg->pData, &((u8 *)(pPager->pMap))[iOffset], pPager->pageSize);
}else{
rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
if( rc==SQLITE_IOERR_SHORT_READ ){
rc = SQLITE_OK;
}
}
}
@@ -3834,13 +3838,14 @@ static int pagerMap(Pager *pPager){
assert( pPager->pMap==0 && pPager->nMap==0 );
rc = sqlite3OsFileSize(pPager->fd, &sz);
sz = sz & ~(4096-1);
if( rc==SQLITE_OK && sz>0 ){
int fd;
rc = sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_GETFD, (void *)&fd);
if( rc==SQLITE_OK ){
void *pMap = mmap(0, sz, PROT_READ, MAP_SHARED, fd, 0);
void *pMap = mmap(0, sz, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if( pMap==MAP_FAILED ){
assert( 0 );
return SQLITE_IOERR;
}
pPager->pMap = pMap;
@@ -3851,6 +3856,22 @@ static int pagerMap(Pager *pPager){
return rc;
}
static int pagerRemap(Pager *pPager, Pgno nPage){
i64 sz = (i64)nPage * pPager->pageSize;
sz = sz & ~(4096-1);
if( pPager->nMap!=sz ){
void *pMap = mremap(pPager->pMap, pPager->nMap, sz, MREMAP_MAYMOVE);
if( pMap==MAP_FAILED ){
return SQLITE_IOERR;
}
pPager->pMap = pMap;
pPager->nMapValid = pPager->nMap = sz;
}
return SQLITE_OK;
}
static int pagerAcquireMapPage(Pager *pPager, Pgno pgno, PgHdr **ppPage){
int rc;
*ppPage = 0;
@@ -4225,7 +4246,11 @@ static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM, pData);
/* Write out the page data. */
rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
if( pPager->nMapValid>=(offset+pPager->pageSize) ){
memcpy(&((u8 *)(pPager->pMap))[offset], pData, pPager->pageSize);
}else{
rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
}
/* If page 1 was just written, update Pager.dbFileVers to match
** the value now stored in the database file. If writing this
@@ -5089,8 +5114,8 @@ int sqlite3PagerSharedLock(Pager *pPager){
** to be the right size but is not actually valid. Avoid this
** possibility by unmapping the db here. */
pagerUnmap(pPager);
}else if( ((i64)nPage*pPager->pageSize)!=pPager->nMap ){
pagerUnmap(pPager);
}else if( pPager->pMap ){
pagerRemap(pPager, nPage);
}
}