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Simplifications and comment improvements in pager.c. (CVS 6926)

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FossilOrigin-Name: 2d2f42ca0a24ed8b33f9ad560c76a6c1301c757b
This commit is contained in:
drh
2009-07-24 12:35:57 +00:00
parent e39f2f9326
commit b480dc2393
3 changed files with 33 additions and 41 deletions
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60
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 1.613 2009/07/22 16:41:15 danielk1977 Exp $
** @(#) $Id: pager.c,v 1.614 2009/07/24 12:35:57 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
@@ -4400,7 +4400,7 @@ int sqlite3PagerWrite(DbPage *pDbPage){
*/
if( rc==SQLITE_OK && needSync ){
assert( !MEMDB && pPager->noSync==0 );
for(ii=0; ii<nPage && needSync; ii++){
for(ii=0; ii<nPage; ii++){
PgHdr *pPage = pager_lookup(pPager, pg1+ii);
if( pPage ){
pPage->flags |= PGHDR_NEED_SYNC;
@@ -4460,12 +4460,12 @@ void sqlite3PagerDontWrite(PgHdr *pPg){
** change-counter, stored as a 4-byte big-endian integer starting at
** byte offset 24 of the pager file.
**
** If the isDirect flag is zero, then this is done by calling
** If the isDirectMode flag is zero, then this is done by calling
** sqlite3PagerWrite() on page 1, then modifying the contents of the
** page data. In this case the file will be updated when the current
** transaction is committed.
**
** The isDirect flag may only be non-zero if the library was compiled
** The isDirectMode flag may only be non-zero if the library was compiled
** with the SQLITE_ENABLE_ATOMIC_WRITE macro defined. In this case,
** if isDirect is non-zero, then the database file is updated directly
** by writing an updated version of page 1 using a call to the
@@ -4485,11 +4485,11 @@ static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
** "if( isDirect )" condition.
*/
#ifndef SQLITE_ENABLE_ATOMIC_WRITE
const int isDirect = 0;
# define DIRECT_MODE 0
assert( isDirectMode==0 );
UNUSED_PARAMETER(isDirectMode);
#else
const int isDirect = isDirectMode;
# define DIRECT_MODE isDirectMode
#endif
assert( pPager->state>=PAGER_RESERVED );
@@ -4506,7 +4506,7 @@ static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
/* If page one was fetched successfully, and this function is not
** operating in direct-mode, make page 1 writable.
*/
if( rc==SQLITE_OK && !isDirect ){
if( rc==SQLITE_OK && !DIRECT_MODE ){
rc = sqlite3PagerWrite(pPgHdr);
}
@@ -4517,14 +4517,14 @@ static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
put32bits(((char*)pPgHdr->pData)+24, change_counter);
/* If running in direct mode, write the contents of page 1 to the file. */
if( isDirect ){
if( DIRECT_MODE ){
const void *zBuf = pPgHdr->pData;
assert( pPager->dbFileSize>0 );
rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
}
/* If everything worked, set the changeCountDone flag. */
if( rc==SQLITE_OK ){
if( rc==SQLITE_OK ){
pPager->changeCountDone = 1;
}
}else{
pPager->changeCountDone = 1;
}
}
@@ -4585,17 +4585,19 @@ int sqlite3PagerCommitPhaseOne(
){
int rc = SQLITE_OK; /* Return code */
if( pPager->errCode ){
return pPager->errCode;
}
/* If a prior error occurred, this routine should not be called. ROLLBACK
** is the appropriate response to an error, not COMMIT. Guard against
** coding errors by repeating the prior error. */
if( NEVER(pPager->errCode) ) return pPager->errCode;
PAGERTRACE(("DATABASE SYNC: File=%s zMaster=%s nSize=%d\n",
pPager->zFilename, zMaster, pPager->dbSize));
/* If this is an in-memory db, or no pages have been written to, or this
** function has already been called, it is a no-op.
*/
if( MEMDB && pPager->dbModified ){
/* If this is an in-memory db, or no pages have been written to, or this
** function has already been called, it is mostly a no-op. However, any
** backup in progress needs to be restarted.
*/
sqlite3BackupRestart(pPager->pBackup);
}else if( pPager->state!=PAGER_SYNCED && pPager->dbModified ){
@@ -4722,14 +4724,6 @@ int sqlite3PagerCommitPhaseOne(
}
commit_phase_one_exit:
if( rc==SQLITE_IOERR_BLOCKED ){
/* pager_incr_changecounter() may attempt to obtain an exclusive
** lock to spill the cache and return IOERR_BLOCKED. But since
** there is no chance the cache is inconsistent, it is
** better to return SQLITE_BUSY.
**/
rc = SQLITE_BUSY;
}
return rc;
}
@@ -4752,18 +4746,16 @@ commit_phase_one_exit:
int sqlite3PagerCommitPhaseTwo(Pager *pPager){
int rc = SQLITE_OK; /* Return code */
/* Do not proceed if the pager is already in the error state. */
if( pPager->errCode ){
return pPager->errCode;
}
/* This routine should not be called if a prior error has occurred.
** But if (due to a coding error elsewhere in the system) it does get
** called, just return the same error code without doing anything. */
if( NEVER(pPager->errCode) ) return pPager->errCode;
/* This function should not be called if the pager is not in at least
** PAGER_RESERVED state. And indeed SQLite never does this. But it is
** nice to have this defensive block here anyway.
** nice to have this defensive test here anyway.
*/
if( NEVER(pPager->state<PAGER_RESERVED) ){
return SQLITE_ERROR;
}
if( NEVER(pPager->state<PAGER_RESERVED) ) return SQLITE_ERROR;
/* An optimization. If the database was not actually modified during
** this transaction, the pager is running in exclusive-mode and is