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More work on windows locking. Fix some problems with unix locking. There

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is still an assertion failure on windows locking in attach2.test. (CVS 1539)

FossilOrigin-Name: 0c2d169cf3c0f36972015c952a2b46cb9a333881
This commit is contained in:
drh
2004-06-07 16:27:46 +00:00
parent 517eb64616
commit 2ac3ee9787
12 changed files with 217 additions and 170 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 1.112 2004/06/04 10:38:31 danielk1977 Exp $
** @(#) $Id: pager.c,v 1.113 2004/06/07 16:27:46 drh Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -1554,20 +1554,16 @@ static int pager_write_pagelist(PgHdr *pList){
** database file. If there is already an EXCLUSIVE lock, the following
** calls to sqlite3OsLock() are no-ops.
**
** The upgrade from a RESERVED to PENDING lock cannot return SQLITE_BUSY,
** unless someone is not following the locking protocol.
** The upgrade from a RESERVED to PENDING might return SQLITE_BUSY on
** windows because the windows locking mechanism acquires a transient
** PENDING lock during its attempts to get a SHARED lock. So if another
** process were trying to get a SHARED lock at the same time this process
** is upgrading from RESERVED to PENDING, the two could collide.
**
** The upgrade from PENDING to EXCLUSIVE can return SQLITE_BUSY. It's
** not totally clear that the busy-callback should be invoked here
** though. (?)
** The upgrade from PENDING to EXCLUSIVE can return SQLITE_BUSY if there
** are still active readers that were created before the PENDING lock
** was acquired.
*/
rc = sqlite3OsLock(&pPager->fd, PENDING_LOCK);
if( rc==SQLITE_BUSY ){
return SQLITE_PROTOCOL;
}
if( rc!=SQLITE_OK ){
return rc;
}
do {
rc = sqlite3OsLock(&pPager->fd, EXCLUSIVE_LOCK);
}while( rc==SQLITE_BUSY &&