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Add the (highly experimental) omit_readlock pragma that disables the use

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of readlocks on read-only databases that are connected using ATTACH. (CVS 2317)

FossilOrigin-Name: 2155448d2128119f74241da0ea07d6713b71765c
This commit is contained in:
drh
2005-02-06 02:45:41 +00:00
parent a2dc3b1a5e
commit 7bec505e26
11 changed files with 71 additions and 36 deletions
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22
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 1.187 2005/01/29 08:32:45 danielk1977 Exp $
** @(#) $Id: pager.c,v 1.188 2005/02/06 02:45:42 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
@@ -250,6 +250,7 @@ struct Pager {
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 */
u8 noReadlock; /* Do not bother to obtain readlocks */
u8 stmtOpen; /* True if the statement subjournal is open */
u8 stmtInUse; /* True we are in a statement subtransaction */
u8 stmtAutoopen; /* Open stmt journal when main journal is opened*/
@@ -1483,7 +1484,7 @@ int sqlite3pager_open(
Pager **ppPager, /* Return the Pager structure here */
const char *zFilename, /* Name of the database file to open */
int nExtra, /* Extra bytes append to each in-memory page */
int useJournal /* TRUE to use a rollback journal on this file */
int flags /* flags controlling this file */
){
Pager *pPager;
char *zFullPathname = 0;
@@ -1494,6 +1495,8 @@ int sqlite3pager_open(
int tempFile = 0;
int memDb = 0;
int readOnly = 0;
int useJournal = (flags & PAGER_OMIT_JOURNAL)==0;
int noReadlock = (flags & PAGER_NO_READLOCK)!=0;
char zTemp[SQLITE_TEMPNAME_SIZE];
*ppPager = 0;
@@ -1556,6 +1559,7 @@ int sqlite3pager_open(
#endif
pPager->journalOpen = 0;
pPager->useJournal = useJournal && !memDb;
pPager->noReadlock = noReadlock && readOnly;
pPager->stmtOpen = 0;
pPager->stmtInUse = 0;
pPager->nRef = 0;
@@ -2144,7 +2148,7 @@ static PgHdr *pager_get_all_dirty_pages(Pager *pPager){
*/
int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage){
PgHdr *pPg;
int rc;
int rc, n;
/* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
** number greater than this, or zero, is requested.
@@ -2165,9 +2169,11 @@ int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage){
** on the database file.
*/
if( pPager->nRef==0 && !MEMDB ){
rc = pager_wait_on_lock(pPager, SHARED_LOCK);
if( rc!=SQLITE_OK ){
return rc;
if( !pPager->noReadlock ){
rc = pager_wait_on_lock(pPager, SHARED_LOCK);
if( rc!=SQLITE_OK ){
return rc;
}
}
/* If a journal file exists, and there is no RESERVED lock on the
@@ -2354,13 +2360,13 @@ int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage){
if( pPager->nExtra>0 ){
memset(PGHDR_TO_EXTRA(pPg, pPager), 0, pPager->nExtra);
}
sqlite3pager_pagecount(pPager);
n = sqlite3pager_pagecount(pPager);
if( pPager->errMask!=0 ){
sqlite3pager_unref(PGHDR_TO_DATA(pPg));
rc = pager_errcode(pPager);
return rc;
}
if( pPager->dbSize<(int)pgno ){
if( n<(int)pgno ){
memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
}else{
int rc;