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Add an optional codec to the pager layer. (CVS 1214)

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FossilOrigin-Name: 2f0c122cfb84dea58d112324a0bdd8b85552a9fa
This commit is contained in:
drh
2004-02-09 01:20:36 +00:00
parent 8e6283155e
commit b20ea9d225
4 changed files with 90 additions and 40 deletions
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109
src/pager.c
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@@ -18,7 +18,7 @@
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.95 2004/02/08 18:07:35 drh Exp $
** @(#) $Id: pager.c,v 1.96 2004/02/09 01:20:37 drh Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -44,6 +44,19 @@ static Pager *mainPager = 0;
#define TRACE3(X,Y,Z)
#endif
/*
** Number of extra bytes of data allocated at the end of each page and
** stored on disk but not used by the higher level btree layer.
*/
#ifndef SQLITE_PAGE_RESERVE
#define SQLITE_PAGE_RESERVE 0
#endif
/*
** The total number of bytes stored on disk for each page.
*/
#define SQLITE_BLOCK_SIZE (SQLITE_PAGE_SIZE+SQLITE_PAGE_RESERVE)
/*
** The page cache as a whole is always in one of the following
@@ -113,7 +126,7 @@ struct PgHdr {
u8 needSync; /* Sync journal before writing this page */
u8 alwaysRollback; /* Disable dont_rollback() for this page */
PgHdr *pDirty; /* Dirty pages sorted by PgHdr.pgno */
/* SQLITE_PAGE_SIZE bytes of page data follow this header */
/* SQLITE_BLOCK_SIZE bytes of page data follow this header */
/* Pager.nExtra bytes of local data follow the page data */
};
@@ -123,7 +136,7 @@ struct PgHdr {
*/
#define PGHDR_TO_DATA(P) ((void*)(&(P)[1]))
#define DATA_TO_PGHDR(D) (&((PgHdr*)(D))[-1])
#define PGHDR_TO_EXTRA(P) ((void*)&((char*)(&(P)[1]))[SQLITE_PAGE_SIZE])
#define PGHDR_TO_EXTRA(P) ((void*)&((char*)(&(P)[1]))[SQLITE_BLOCK_SIZE])
/*
** How big to make the hash table used for locating in-memory pages
@@ -158,6 +171,8 @@ struct Pager {
int nRef; /* Number of in-memory pages with PgHdr.nRef>0 */
int mxPage; /* Maximum number of pages to hold in cache */
int nHit, nMiss, nOvfl; /* Cache hits, missing, and LRU overflows */
void (*xCodec)(void*,void*,int); /* Routine for en/decoding on-disk data */
void *pCodecArg; /* First argument to xCodec() */
u8 journalOpen; /* True if journal file descriptors is valid */
u8 journalStarted; /* True if header of journal is synced */
u8 useJournal; /* Use a rollback journal on this file */
@@ -201,8 +216,8 @@ struct Pager {
*/
typedef struct PageRecord PageRecord;
struct PageRecord {
Pgno pgno; /* The page number */
char aData[SQLITE_PAGE_SIZE]; /* Original data for page pgno */
Pgno pgno; /* The page number */
char aData[SQLITE_BLOCK_SIZE]; /* Original data for page pgno */
};
/*
@@ -225,7 +240,7 @@ struct PageRecord {
**
** The sanity checking information for the 3rd journal format consists
** of a 32-bit checksum on each page of data. The checksum covers both
** the page number and the SQLITE_PAGE_SIZE bytes of data for the page.
** the page number and the SQLITE_BLOCK_SIZE bytes of data for the page.
** This cksum is initialized to a 32-bit random value that appears in the
** journal file right after the header. The random initializer is important,
** because garbage data that appears at the end of a journal is likely
@@ -270,7 +285,7 @@ int journal_format = 3;
#define JOURNAL_HDR_SZ(X) \
(sizeof(aJournalMagic1) + sizeof(Pgno) + ((X)>=3)*2*sizeof(u32))
#define JOURNAL_PG_SZ(X) \
(SQLITE_PAGE_SIZE + sizeof(Pgno) + ((X)>=3)*sizeof(u32))
(SQLITE_BLOCK_SIZE + sizeof(Pgno) + ((X)>=3)*sizeof(u32))
/*
** Enable reference count tracking here:
@@ -548,18 +563,21 @@ static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int format){
*/
pPg = pager_lookup(pPager, pgRec.pgno);
TRACE2("PLAYBACK %d\n", pgRec.pgno);
sqliteOsSeek(&pPager->fd, (pgRec.pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqliteOsWrite(&pPager->fd, pgRec.aData, SQLITE_PAGE_SIZE);
sqliteOsSeek(&pPager->fd, (pgRec.pgno-1)*(off_t)SQLITE_BLOCK_SIZE);
rc = sqliteOsWrite(&pPager->fd, pgRec.aData, SQLITE_BLOCK_SIZE);
if( pPg ){
/* No page should ever be rolled back that is in use, except for page
** 1 which is held in use in order to keep the lock on the database
** active.
*/
assert( pPg->nRef==0 || pPg->pgno==1 );
memcpy(PGHDR_TO_DATA(pPg), pgRec.aData, SQLITE_PAGE_SIZE);
memcpy(PGHDR_TO_DATA(pPg), pgRec.aData, SQLITE_BLOCK_SIZE);
memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra);
pPg->dirty = 0;
pPg->needSync = 0;
if( pPager->xCodec ){
pPager->xCodec(pPager->pCodecArg, PGHDR_TO_DATA(pPg), 0);
}
}
return rc;
}
@@ -583,7 +601,7 @@ static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int format){
** database to during a rollback.
** * Zero or more pages instances, each as follows:
** + 4 byte page number.
** + SQLITE_PAGE_SIZE bytes of data.
** + SQLITE_BLOCK_SIZE bytes of data.
** + 4 byte checksum (format 3 only)
**
** When we speak of the journal header, we mean the first 4 bullets above.
@@ -689,7 +707,7 @@ static int pager_playback(Pager *pPager, int useJournalSize){
goto end_playback;
}
assert( pPager->origDbSize==0 || pPager->origDbSize==mxPg );
rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)mxPg);
rc = sqliteOsTruncate(&pPager->fd, SQLITE_BLOCK_SIZE*(off_t)mxPg);
if( rc!=SQLITE_OK ){
goto end_playback;
}
@@ -714,17 +732,20 @@ static int pager_playback(Pager *pPager, int useJournalSize){
if( rc==SQLITE_OK ){
PgHdr *pPg;
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
char zBuf[SQLITE_PAGE_SIZE];
char zBuf[SQLITE_BLOCK_SIZE];
if( !pPg->dirty ) continue;
if( (int)pPg->pgno <= pPager->origDbSize ){
sqliteOsSeek(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)(pPg->pgno-1));
rc = sqliteOsRead(&pPager->fd, zBuf, SQLITE_PAGE_SIZE);
sqliteOsSeek(&pPager->fd, SQLITE_BLOCK_SIZE*(off_t)(pPg->pgno-1));
rc = sqliteOsRead(&pPager->fd, zBuf, SQLITE_BLOCK_SIZE);
if( rc ) break;
if( pPager->xCodec ){
pPager->xCodec(pPager->pCodecArg, zBuf, 0);
}
}else{
memset(zBuf, 0, SQLITE_PAGE_SIZE);
memset(zBuf, 0, SQLITE_BLOCK_SIZE);
}
if( pPg->nRef==0 || memcmp(zBuf, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE) ){
memcpy(PGHDR_TO_DATA(pPg), zBuf, SQLITE_PAGE_SIZE);
if( pPg->nRef==0 || memcmp(zBuf, PGHDR_TO_DATA(pPg), SQLITE_BLOCK_SIZE) ){
memcpy(PGHDR_TO_DATA(pPg), zBuf, SQLITE_BLOCK_SIZE);
memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra);
}
pPg->needSync = 0;
@@ -765,7 +786,7 @@ static int pager_ckpt_playback(Pager *pPager){
/* Truncate the database back to its original size.
*/
rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)pPager->ckptSize);
rc = sqliteOsTruncate(&pPager->fd, SQLITE_BLOCK_SIZE*(off_t)pPager->ckptSize);
pPager->dbSize = pPager->ckptSize;
/* Figure out how many records are in the checkpoint journal.
@@ -1003,7 +1024,7 @@ int sqlitepager_pagecount(Pager *pPager){
pPager->errMask |= PAGER_ERR_DISK;
return 0;
}
n /= SQLITE_PAGE_SIZE;
n /= SQLITE_BLOCK_SIZE;
if( pPager->state!=SQLITE_UNLOCK ){
pPager->dbSize = n;
}
@@ -1031,7 +1052,7 @@ int sqlitepager_truncate(Pager *pPager, Pgno nPage){
return SQLITE_OK;
}
syncJournal(pPager);
rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)nPage);
rc = sqliteOsTruncate(&pPager->fd, SQLITE_BLOCK_SIZE*(off_t)nPage);
if( rc==SQLITE_OK ){
pPager->dbSize = nPage;
}
@@ -1238,8 +1259,14 @@ static int pager_write_pagelist(PgHdr *pList){
pPager = pList->pPager;
while( pList ){
assert( pList->dirty );
sqliteOsSeek(&pPager->fd, (pList->pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqliteOsWrite(&pPager->fd, PGHDR_TO_DATA(pList), SQLITE_PAGE_SIZE);
sqliteOsSeek(&pPager->fd, (pList->pgno-1)*(off_t)SQLITE_BLOCK_SIZE);
if( pPager->xCodec ){
pPager->xCodec(pPager->pCodecArg, PGHDR_TO_DATA(pList), 1);
}
rc = sqliteOsWrite(&pPager->fd, PGHDR_TO_DATA(pList), SQLITE_BLOCK_SIZE);
if( pPager->xCodec ){
pPager->xCodec(pPager->pCodecArg, PGHDR_TO_DATA(pList), 0);
}
if( rc ) return rc;
pList->dirty = 0;
pList = pList->pDirty;
@@ -1363,7 +1390,7 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
pPager->nMiss++;
if( pPager->nPage<pPager->mxPage || pPager->pFirst==0 ){
/* Create a new page */
pPg = sqliteMallocRaw( sizeof(*pPg) + SQLITE_PAGE_SIZE
pPg = sqliteMallocRaw( sizeof(*pPg) + SQLITE_BLOCK_SIZE
+ sizeof(u32) + pPager->nExtra );
if( pPg==0 ){
pager_unwritelock(pPager);
@@ -1495,20 +1522,22 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
return rc;
}
if( pPager->dbSize<(int)pgno ){
memset(PGHDR_TO_DATA(pPg), 0, SQLITE_PAGE_SIZE);
memset(PGHDR_TO_DATA(pPg), 0, SQLITE_BLOCK_SIZE);
}else{
int rc;
sqliteOsSeek(&pPager->fd, (pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqliteOsRead(&pPager->fd, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE);
sqliteOsSeek(&pPager->fd, (pgno-1)*(off_t)SQLITE_BLOCK_SIZE);
rc = sqliteOsRead(&pPager->fd, PGHDR_TO_DATA(pPg), SQLITE_BLOCK_SIZE);
if( rc!=SQLITE_OK ){
off_t fileSize;
if( sqliteOsFileSize(&pPager->fd,&fileSize)!=SQLITE_OK
|| fileSize>=pgno*SQLITE_PAGE_SIZE ){
|| fileSize>=pgno*SQLITE_BLOCK_SIZE ){
sqlitepager_unref(PGHDR_TO_DATA(pPg));
return rc;
}else{
memset(PGHDR_TO_DATA(pPg), 0, SQLITE_PAGE_SIZE);
memset(PGHDR_TO_DATA(pPg), 0, SQLITE_BLOCK_SIZE);
}
}else if( pPager->xCodec ){
pPager->xCodec(pPager->pCodecArg, PGHDR_TO_DATA(pPg), 0);
}
}
}else{
@@ -1787,7 +1816,13 @@ int sqlitepager_write(void *pData){
szPg = SQLITE_PAGE_SIZE+4;
}
store32bits(pPg->pgno, pPg, -4);
if( pPager->xCodec ){
pPager->xCodec(pPager->pCodecArg, pData, 1);
}
rc = sqliteOsWrite(&pPager->jfd, &((char*)pData)[-4], szPg);
if( pPager->xCodec ){
pPager->xCodec(pPager->pCodecArg, pData, 0);
}
if( journal_format>=JOURNAL_FORMAT_3 ){
*(u32*)PGHDR_TO_EXTRA(pPg) = saved;
}
@@ -1823,7 +1858,7 @@ int sqlitepager_write(void *pData){
if( pPager->ckptInUse && !pPg->inCkpt && (int)pPg->pgno<=pPager->ckptSize ){
assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize );
store32bits(pPg->pgno, pPg, -4);
rc = sqliteOsWrite(&pPager->cpfd, &((char*)pData)[-4], SQLITE_PAGE_SIZE+4);
rc = sqliteOsWrite(&pPager->cpfd, &((char*)pData)[-4], SQLITE_BLOCK_SIZE+4);
if( rc!=SQLITE_OK ){
sqlitepager_rollback(pPager);
pPager->errMask |= PAGER_ERR_FULL;
@@ -1865,7 +1900,7 @@ int sqlitepager_overwrite(Pager *pPager, Pgno pgno, void *pData){
if( rc==SQLITE_OK ){
rc = sqlitepager_write(pPage);
if( rc==SQLITE_OK ){
memcpy(pPage, pData, SQLITE_PAGE_SIZE);
memcpy(pPage, pData, SQLITE_BLOCK_SIZE);
}
sqlitepager_unref(pPage);
}
@@ -2165,6 +2200,18 @@ const char *sqlitepager_filename(Pager *pPager){
return pPager->zFilename;
}
/*
** Set the codec for this pager
*/
void sqlitepager_set_codec(
Pager *pPager,
void (*xCodec)(void*,void*,int),
void *pCodecArg
){
pPager->xCodec = xCodec;
pPager->pCodecArg = pCodecArg;
}
#ifdef SQLITE_TEST
/*
** Print a listing of all referenced pages and their ref count.