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BTree and pager are working pretty well now. (CVS 234)

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FossilOrigin-Name: a84fb078baf96dbfb5983981127dfc905074b7f9
This commit is contained in:
drh
2001-07-02 17:51:45 +00:00
parent efc251da92
commit 6019e168a0
9 changed files with 324 additions and 111 deletions
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52
src/pager.c
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@@ -27,7 +27,7 @@
** all writes in order to support rollback. Locking is used to limit
** access to one or more reader or one writer.
**
** @(#) $Id: pager.c,v 1.12 2001/06/28 01:54:49 drh Exp $
** @(#) $Id: pager.c,v 1.13 2001/07/02 17:51:46 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
@@ -122,6 +122,7 @@ struct Pager {
int nHit, nMiss, nOvfl; /* Cache hits, missing, and LRU overflows */
unsigned char state; /* SQLITE_UNLOCK, _READLOCK or _WRITELOCK */
unsigned char errMask; /* One of several kinds of errors */
unsigned char *aInJournal; /* One bit for each page in the database file */
PgHdr *pFirst, *pLast; /* List of free pages */
PgHdr *pAll; /* List of all pages */
PgHdr *aHash[N_PG_HASH]; /* Hash table to map page number of PgHdr */
@@ -210,6 +211,7 @@ static int pager_unlock(fd){
** the beginning of the file.
*/
static int pager_seek(int fd, off_t whereto){
/*printf("SEEK to page %d\n", whereto/SQLITE_PAGE_SIZE + 1);*/
lseek(fd, whereto, SEEK_SET);
return SQLITE_OK;
}
@@ -232,6 +234,7 @@ static int pager_truncate(int fd, Pgno mxPg){
*/
static int pager_read(int fd, void *pBuf, int nByte){
int rc;
/* printf("READ\n");*/
rc = read(fd, pBuf, nByte);
if( rc<0 ){
memset(pBuf, 0, nByte);
@@ -253,6 +256,7 @@ static int pager_read(int fd, void *pBuf, int nByte){
*/
static int pager_write(int fd, const void *pBuf, int nByte){
int rc;
/*printf("WRITE\n");*/
rc = write(fd, pBuf, nByte);
if( rc<nByte ){
return SQLITE_FULL;
@@ -338,6 +342,8 @@ static int pager_unwritelock(Pager *pPager){
unlink(pPager->zJournal);
close(pPager->jfd);
pPager->jfd = -1;
sqliteFree( pPager->aInJournal );
pPager->aInJournal = 0;
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
pPg->inJournal = 0;
pPg->dirty = 0;
@@ -434,6 +440,7 @@ static int pager_playback(Pager *pPager){
pPg = pager_lookup(pPager, pgRec.pgno);
if( pPg ){
memcpy(PGHDR_TO_DATA(pPg), pgRec.aData, SQLITE_PAGE_SIZE);
memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra);
}
rc = pager_seek(pPager->fd, (pgRec.pgno-1)*SQLITE_PAGE_SIZE);
if( rc!=SQLITE_OK ) break;
@@ -719,9 +726,9 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
/* Recycle an older page. First locate the page to be recycled.
** Try to find one that is not dirty and is near the head of
** of the free list */
int cnt = 4;
int cnt = pPager->mxPage/2;
pPg = pPager->pFirst;
while( pPg->dirty && 0<cnt-- ){
while( pPg->dirty && 0<cnt-- && pPg->pNextFree ){
pPg = pPg->pNextFree;
}
if( pPg==0 || pPg->dirty ) pPg = pPager->pFirst;
@@ -752,12 +759,19 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
/* Unlink the old page from the free list and the hash table
*/
pPager->pFirst = pPg->pNextFree;
if( pPager->pFirst ){
pPager->pFirst->pPrevFree = 0;
if( pPg->pPrevFree ){
pPg->pPrevFree->pNextFree = pPg->pNextFree;
}else{
pPager->pLast = 0;
assert( pPager->pFirst==pPg );
pPager->pFirst = pPg->pNextFree;
}
if( pPg->pNextFree ){
pPg->pNextFree->pPrevFree = pPg->pPrevFree;
}else{
assert( pPager->pLast==pPg );
pPager->pLast = pPg->pPrevFree;
}
pPg->pNextFree = pPg->pPrevFree = 0;
if( pPg->pNextHash ){
pPg->pNextHash->pPrevHash = pPg->pPrevHash;
}
@@ -768,10 +782,15 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
assert( pPager->aHash[h]==pPg );
pPager->aHash[h] = pPg->pNextHash;
}
pPg->pNextHash = pPg->pPrevHash = 0;
pPager->nOvfl++;
}
pPg->pgno = pgno;
pPg->inJournal = 0;
if( pPager->aInJournal && pgno<=pPager->origDbSize ){
pPg->inJournal = (pPager->aInJournal[pgno/8] & (1<<(pgno&7)))!=0;
}else{
pPg->inJournal = 0;
}
pPg->dirty = 0;
pPg->nRef = 1;
REFINFO(pPg);
@@ -910,6 +929,11 @@ int sqlitepager_write(void *pData){
if( pPg->inJournal ){ return SQLITE_OK; }
assert( pPager->state!=SQLITE_UNLOCK );
if( pPager->state==SQLITE_READLOCK ){
assert( pPager->aInJournal==0 );
pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 );
if( pPager->aInJournal==0 ){
return SQLITE_NOMEM;
}
pPager->jfd = open(pPager->zJournal, O_RDWR|O_CREAT, 0644);
if( pPager->jfd<0 ){
return SQLITE_CANTOPEN;
@@ -952,6 +976,8 @@ int sqlitepager_write(void *pData){
pPager->errMask |= PAGER_ERR_FULL;
return rc;
}
assert( pPager->aInJournal!=0 );
pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7);
}
pPg->inJournal = 1;
if( pPager->dbSize<pPg->pgno ){
@@ -960,6 +986,16 @@ int sqlitepager_write(void *pData){
return rc;
}
/*
** Return TRUE if the page given in the argument was previous passed
** to sqlitepager_write(). In other words, return TRUE if it is ok
** to change the content of the page.
*/
int sqlitepager_iswriteable(void *pData){
PgHdr *pPg = DATA_TO_PGHDR(pData);
return pPg->dirty;
}
/*
** Commit all changes to the database and release the write lock.
**