Conjecture: a journal header with nRec==0 must be the last header in the

journal.  Add asserts to make this conjecture explicit. (CVS 6132)

FossilOrigin-Name: 15b5b5f90c2ffa79155cdc2dbc4fb5583cb72017

diff --git a/manifest b/manifest
index 061ce427ff397b73d26b216d144e5e61c8279836..8f41891265750228b5d9bf3b459411c524d3ecf1 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sfor\s'truncate\sfile'\soperations\son\sin-memory\sdatabases.\s(CVS\s6131)
-D 2009-01-07T15:18:21
+C Conjecture:\sa\sjournal\sheader\swith\snRec==0\smust\sbe\sthe\slast\sheader\sin\sthe\njournal.\s\sAdd\sasserts\sto\smake\sthis\sconjecture\sexplicit.\s(CVS\s6132)
+D 2009-01-07T15:33:46
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 05461a9b5803d5ad10c79f989801e9fd2cc3e592
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -142,7 +142,7 @@ F src/os_common.h 24525d8b7bce66c374dfc1810a6c9043f3359b60
 F src/os_os2.c bed77dc26e3a95ce4a204936b9a1ca6fe612fcc5
 F src/os_unix.c e6eacc7ec735ded605fefcbaf250058baa8feb12
 F src/os_win.c 496e3ceb499aedc63622a89ef76f7af2dd902709
-F src/pager.c a799290e5cf9495f9991413ce84847011767b4d9
+F src/pager.c 2fd6d5a88a8a2a7222398640d88d0094a221b240
 F src/pager.h 9870acb2d653848d90d765d7cbf163496d6c8111
 F src/parse.y 4d0e33a702dc3ea7b69d8ae1914b3fbd32e46057
 F src/pcache.c 16dc8da6e6ba6250f8dfd9ee46036db1cbceedc6
@@ -475,7 +475,7 @@ F test/pager2.test d4b7f6b70ff018b9995e622a32526b275f515042
 F test/pager3.test 2323bf27fd5bd887b580247e5bce500ceee994b4
 F test/pageropt.test 3ee6578891baaca967f0bd349e4abfa736229e1a
 F test/pagesize.test 0d9ff3fedfce6e5ffe8fa7aca9b6d3433a2e843b
-F test/pcache.test 515b4c26e9f57660357dfff5b6b697acac1abc5f
+F test/pcache.test ccd18b4d2b432f44319a82b0367ed843ee18cebd
 F test/pcache2.test 46efd980a89f737847b99327bda19e08fe11e402
 F test/permutations.test af0962c17a32631de8b301c301c497adea9739f4
 F test/pragma.test 325aa0833d483b8e0c98e8196f1cc49fa5d8c336
@@ -692,7 +692,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P 04387ae10ab3be24c93497f4af6f48d6832f37eb
-R cd03e1b03d4149ac01b912dddfeb4003
-U danielk1977
-Z 242d556585dea66787f6cacf6e86748b
+P 83d1eafbde556f56969c6f285b6767d2c658dbfc
+R e0c72c9528a9fa2ec3f8b366bc70534d
+U drh
+Z 5a8b01afe6b4e3b34d058c12ce65dc71

diff --git a/manifest.uuid b/manifest.uuid
index 14af207e6b099d27733de42858e4a11496d4908e..623b96ccd2d7e33a7266e4e288abbc7aafc30774 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-83d1eafbde556f56969c6f285b6767d2c658dbfc
\ No newline at end of file
+15b5b5f90c2ffa79155cdc2dbc4fb5583cb72017
\ No newline at end of file

diff --git a/src/pager.c b/src/pager.c
index 130c8255ec4dad9426933bcf4a00e5241ac1ceba..5a7be86a642016c0d05a636ba5bc48a8a3096d58 100644 (file)
--- a/src/pager.c
+++ b/src/pager.c
@@ -18,7 +18,7 @@
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.538 2009/01/07 15:18:21 danielk1977 Exp $
+** @(#) $Id: pager.c,v 1.539 2009/01/07 15:33:46 drh Exp $
 */
 #ifndef SQLITE_OMIT_DISKIO
 #include "sqliteInt.h"
@@ -1315,7 +1315,7 @@ static int pager_playback_one_page(
   return rc;
 }
 
-#if /* !defined(NDEBUG) || */ defined(SQLITE_COVERAGE_TEST)
+#if !defined(NDEBUG) || defined(SQLITE_COVERAGE_TEST)
 /*
 ** This routine looks ahead into the main journal file and determines
 ** whether or not the next record (the record that begins at file
@@ -1646,12 +1646,15 @@ static int pager_playback(Pager *pPager, int isHot){
     ** when doing a ROLLBACK and the nRec==0 chunk is the last chunk in
     ** the journal, it means that the journal might contain additional
     ** pages that need to be rolled back and that the number of pages 
-    ** should be computed based on the journal file size.  
+    ** should be computed based on the journal file size.
+    **
+    ** 2009-01-07:  We think #2565 is now unreachable due to changes
+    ** in the pcache.  The assert that follows will fire if we are wrong.
     */
-    testcase( nRec==0 && !isHot
+    assert( !(nRec==0 && !isHot
          && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)!=pPager->journalOff
          && ((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager))>0
-         && pagerNextJournalPageIsValid(pPager)
+         && pagerNextJournalPageIsValid(pPager))
     );
     if( nRec==0 && !isHot &&
         pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
@@ -1784,10 +1787,10 @@ static int pagerPlaybackSavepoint(Pager *pPager, PagerSavepoint *pSavepoint){
     ** test is related to ticket #2565.  See the discussion in the
     ** pager_playback() function for additional information.
     */
-    testcase( nJRec==0
+    assert( !(nJRec==0
          && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)!=pPager->journalOff
          && ((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager))>0
-         && pagerNextJournalPageIsValid(pPager)
+         && pagerNextJournalPageIsValid(pPager))
     );
     if( nJRec==0 
      && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
@@ -3574,18 +3577,27 @@ int sqlite3PagerWrite(DbPage *pDbPage){
       }
     }
 
-    /* If the PgHdr.needSync flag is set for any of the nPage pages 
+    /* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages 
     ** starting at pg1, then it needs to be set for all of them. Because
     ** writing to any of these nPage pages may damage the others, the
     ** journal file must contain sync()ed copies of all of them
     ** before any of them can be written out to the database file.
+    **
+    ** 2009-01-07:  This block of code appears to be a no-op.  I do not
+    ** believe it is possible for any page on the sector to not have
+    ** the PGHDR_NEED_SYNC flag set.  The "pPage->flags |= PGHDR_NEED_SYNC"
+    ** line below does nothing, I think.  But it does no harm to leave
+    ** this code in place until we can definitively prove this is the case.
     */
     if( needSync ){
       assert( !MEMDB && pPager->noSync==0 );
       for(ii=0; ii<nPage && needSync; ii++){
         PgHdr *pPage = pager_lookup(pPager, pg1+ii);
-        if( pPage ) pPage->flags |= PGHDR_NEED_SYNC;
-        sqlite3PagerUnref(pPage);
+        if( pPage ){
+          assert( pPage->flags & PGHDR_NEED_SYNC ); /* 2009-01-07 conjecture */
+          pPage->flags |= PGHDR_NEED_SYNC;
+          sqlite3PagerUnref(pPage);
+        }
       }
       assert(pPager->needSync);
     }

diff --git a/test/pcache.test b/test/pcache.test
index 0971319277d52c25e9efbae0a22f1ff6b2ae65ee..ad024fc373164f762fd4bf4cf733378f3ccfdb6c 100644 (file)
--- a/test/pcache.test
+++ b/test/pcache.test
@@ -11,7 +11,7 @@
 #
 # This file is focused on testing the pcache module.
 #
-# $Id: pcache.test,v 1.2 2008/09/05 05:29:09 danielk1977 Exp $
+# $Id: pcache.test,v 1.3 2009/01/07 15:33:46 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -64,7 +64,7 @@ do_test pcache-1.5 {
   pcache_stats
 } {current 11 max 20 min 20 recyclable 1}
 
-do_test pcache-1.6 {
+do_test pcache-1.6.1 {
   execsql {
     BEGIN;
     SELECT * FROM sqlite_master;
@@ -76,7 +76,7 @@ do_test pcache-1.6 {
 # single pinned page in its cache. Connection [db] is holding 10 dirty 
 # pages. It cannot recycle them because of the read lock held by db2.
 #
-do_test pcache-1.6 {
+do_test pcache-1.6.2 {
   execsql {
     CREATE INDEX i1 ON t1(a, b);
     CREATE INDEX i2 ON t2(a, b);
@@ -144,4 +144,3 @@ do_test pcache-1.13 {
 } {current 15 max 15 min 10 recyclable 15}
 
 finish_test
-