A minor logic correction in the previous check-in. Also added a lengthy
comment describing the meanings of various flags in the
{quote: PgHdr} structure. (CVS 4080)
FossilOrigin-Name: 57bf8204cde47dfeb31c064f2b128b9a8d94189f
This commit is contained in:
drh
parent
5e3853112a
commit
732c817f8b
12
manifest
12
manifest
@ -1,5 +1,5 @@
|
||||
C Fix\sa\sdatabase\scorruption\sproblem\sthat\scan\soccur\sin\sauto-vacuum\smode\swhen\na\smalloc()\sfailure\scauses\sa\sstatement\srollback,\sadditional\sstatements\nare\srun\sin\sthe\ssame\stransaction,\sthen\sthe\stotal\stransaction\srolls\sback.\s(CVS\s4079)
|
||||
D 2007-06-16T04:42:12
|
||||
C A\sminor\slogic\scorrection\sin\sthe\sprevious\scheck-in.\s\sAlso\sadded\sa\slengthy\r\ncomment\sdescribing\sthe\smeanings\sof\svarious\sflags\sin\sthe\s\r\n{quote:\sPgHdr}\sstructure.\s(CVS\s4080)
|
||||
D 2007-06-16T11:17:46
|
||||
F Makefile.in b9971ab07868cf2b3209fe3bf8c52e7e25af4193
|
||||
F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
|
||||
F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
|
||||
@ -94,7 +94,7 @@ F src/os_unix.c f2ccf2e9a925fc679faf7a8fe85700e0f13cf0e1
|
||||
F src/os_unix.h 5768d56d28240d3fe4537fac08cc85e4fb52279e
|
||||
F src/os_win.c d868d5f9e95ec9c1b9e2a30c54c996053db6dddd
|
||||
F src/os_win.h 41a946bea10f61c158ce8645e7646b29d44f122b
|
||||
F src/pager.c a8e5c2fd00737ddd7d8c8416d0fdbbf904d78b64
|
||||
F src/pager.c d7e2b57f573aa3e4183c6112a4e7b5dd480b25e1
|
||||
F src/pager.h 94110a5570dca30d54a883e880a3633b2e4c05ae
|
||||
F src/parse.y 2ed1d91fdcb4ae7ae7d1f4674544297807c7cc26
|
||||
F src/pragma.c 0d25dad58bdfd6789943a10f1b9663c2eb85b96d
|
||||
@ -506,7 +506,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
|
||||
F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
|
||||
F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
|
||||
F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
|
||||
P dcdb20f81ae923f6f56d75c7b8b89a0b3abff954
|
||||
R e52cc159103410bf628cb2caa9ba87b2
|
||||
P c9dcf2b926c99ff9cee68589f364461ab2a1d11f
|
||||
R 74c0238a5e30e1bd72611d04385a904b
|
||||
U drh
|
||||
Z 5e8ccb501c2183f5e479995480e6033d
|
||||
Z 50e1ec7f55bb4b42bf19c7a688ba2066
|
||||
|
||||
@ -1 +1 @@
|
||||
c9dcf2b926c99ff9cee68589f364461ab2a1d11f
|
||||
57bf8204cde47dfeb31c064f2b128b9a8d94189f
|
||||
78
src/pager.c
78
src/pager.c
@ -18,7 +18,7 @@
|
||||
** file simultaneously, or one process from reading the database while
|
||||
** another is writing.
|
||||
**
|
||||
** @(#) $Id: pager.c,v 1.345 2007/06/16 04:42:12 drh Exp $
|
||||
** @(#) $Id: pager.c,v 1.346 2007/06/16 11:17:46 drh Exp $
|
||||
*/
|
||||
#ifndef SQLITE_OMIT_DISKIO
|
||||
#include "sqliteInt.h"
|
||||
@ -150,6 +150,78 @@
|
||||
** The PgHdr.dirty flag is set when sqlite3PagerWrite() is called and
|
||||
** is cleared again when the page content is written back to the original
|
||||
** database file.
|
||||
**
|
||||
** Details of important structure elements:
|
||||
**
|
||||
** needSync
|
||||
**
|
||||
** If this is true, this means that it is not safe to write the page
|
||||
** content to the database because the original content needed
|
||||
** for rollback has not by synced to the main rollback journal.
|
||||
** The original content may have been written to the rollback journal
|
||||
** but it has not yet been synced. So we cannot write to the database
|
||||
** file because power failure might cause the page in the journal file
|
||||
** to never reach the disk. It is as if the write to the journal file
|
||||
** does not occur until the journal file is synced.
|
||||
**
|
||||
** This flag is false if the page content exactly matches what
|
||||
** currently exists in the database file. The needSync flag is also
|
||||
** false if the original content has been written to the main rollback
|
||||
** journal and synced. If the page represents a new page that has
|
||||
** been added onto the end of the database during the current
|
||||
** transaction, the needSync flag is true until the original database
|
||||
** size in the journal header has been synced to disk.
|
||||
**
|
||||
** inJournal
|
||||
**
|
||||
** This is true if the original page has been written into the main
|
||||
** rollback journal. This is always false for new pages added to
|
||||
** the end of the database file during the current transaction.
|
||||
** And this flag says nothing about whether or not the journal
|
||||
** has been synced to disk. For pages that are in the original
|
||||
** database file, the following expression should always be true:
|
||||
**
|
||||
** inJournal = (pPager->aInJournal[(pgno-1)/8] & (1<<((pgno-1)%8))!=0
|
||||
**
|
||||
** The pPager->aInJournal[] array is only valid for the original
|
||||
** pages of the database, not new pages that are added to the end
|
||||
** of the database, so obviously the above expression cannot be
|
||||
** valid for new pages. For new pages inJournal is always 0.
|
||||
**
|
||||
** dirty
|
||||
**
|
||||
** When true, this means that the content of the page has been
|
||||
** modified and needs to be written back to the database file.
|
||||
** If false, it means that either the content of the page is
|
||||
** unchanged or else the content is unimportant and we do not
|
||||
** care whether or not it is preserved.
|
||||
**
|
||||
** alwaysRollback
|
||||
**
|
||||
** This means that the sqlite3PagerDontRollback() API should be
|
||||
** ignored for this page. The DontRollback() API attempts to say
|
||||
** that the content of the page on disk is unimportant (it is an
|
||||
** unused page on the freelist) so that it is unnecessary to
|
||||
** rollback changes to this page because the content of the page
|
||||
** can change without changing the meaning of the database. This
|
||||
** flag overrides any DontRollback() attempt. This flag is set
|
||||
** when a page that originally contained valid data is added to
|
||||
** the freelist. Later in the same transaction, this page might
|
||||
** be pulled from the freelist and reused for something different
|
||||
** and at that point the DontRollback() API will be called because
|
||||
** pages taken from the freelist do not need to be protected by
|
||||
** the rollback journal. But this flag says that the page was
|
||||
** not originally part of the freelist so that it still needs to
|
||||
** be rolled back in spite of any subsequent DontRollback() calls.
|
||||
**
|
||||
** needRead
|
||||
**
|
||||
** This flag means (when true) that the content of the page has
|
||||
** not yet been loaded from disk. The in-memory content is just
|
||||
** garbage. (Actually, we zero the content, but you should not
|
||||
** make any assumptions about the content nevertheless.) If the
|
||||
** content is needed in the future, it should be read from the
|
||||
** original database file.
|
||||
*/
|
||||
typedef struct PgHdr PgHdr;
|
||||
struct PgHdr {
|
||||
@ -4299,11 +4371,9 @@ int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno){
|
||||
}
|
||||
if( pPager->aInJournal && (int)pgno<=pPager->origDbSize ){
|
||||
pPg->inJournal = (pPager->aInJournal[pgno/8] & (1<<(pgno&7)))!=0;
|
||||
}else if( (int)pgno>=pPager->origDbSize ){
|
||||
pPg->inJournal = 1;
|
||||
}else{
|
||||
pPg->inJournal = 0;
|
||||
assert( pPg->needSync==0 );
|
||||
assert( pPg->needSync==0 || (int)pgno>pPager->origDbSize );
|
||||
}
|
||||
|
||||
/* Change the page number for pPg and insert it into the new hash-chain. */
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user