From 0626bd65fb67288201b738a38ad73bba3e8fe341 Mon Sep 17 00:00:00 2001
From: dan <dan@noemail.net>
Date: Sat, 5 Jun 2010 14:42:57 +0000
Subject: [PATCH] Mark a condition in wal.c as ALWAYS().

FossilOrigin-Name: 3fe0cc784ac586358c08f87fba458dfbb5eec6f2
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/wal.c     | 17 ++++++++++++++++-
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/manifest b/manifest
index 172043c4ec..e273be4a1d 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sextra\scoverage\stest\scases\sfor\swal.c.\sNo\schanges\sto\sproduction\scode.
-D 2010-06-05T11:53:34
+C Mark\sa\scondition\sin\swal.c\sas\sALWAYS().
+D 2010-06-05T14:42:58
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in a5cad1f8f3e021356bfcc6c77dc16f6f1952bbc3
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -224,7 +224,7 @@ F src/vdbeblob.c 5327132a42a91e8b7acfb60b9d2c3b1c5c863e0e
 F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1
 F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2
 F src/vtab.c a0f8a40274e4261696ef57aa806de2776ab72cda
-F src/wal.c e237581eeb99a9c766419e824c766ac67f37adb9
+F src/wal.c 3a448ad3a563b7b9fe6982e69f56fab327eda196
 F src/wal.h 4ace25262452d17e7d3ec970c89ee17794004008
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
 F src/where.c 75fee9e255b62f773fcadd1d1f25b6f63ac7a356
@@ -817,7 +817,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 255850699ddbf4aad8cc3223aefbada35daa0703
-R 7ac85a4afc11bde0cbb8862c4d4688fc
+P f9d4ae0e8cc5d32c52eb78799f7959dd236ea9de
+R 354467ef49285b1e7f4721d72defda65
 U dan
-Z 575989e6baec836caf7d32e1a4d39d95
+Z 2159f852b96b4a4c0e2c6c207c85dab6
diff --git a/manifest.uuid b/manifest.uuid
index 8218c59fed..fe64f89fa3 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-f9d4ae0e8cc5d32c52eb78799f7959dd236ea9de
\ No newline at end of file
+3fe0cc784ac586358c08f87fba458dfbb5eec6f2
\ No newline at end of file
diff --git a/src/wal.c b/src/wal.c
index 6633784b62..dcff296793 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -2085,8 +2085,23 @@ int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
       rc = walIndexMap(pWal, walMappingSize(iMax));
     }
     if( rc==SQLITE_OK ){
-      for(iFrame=pWal->hdr.mxFrame+1; rc==SQLITE_OK && iFrame<=iMax; iFrame++){
+      for(iFrame=pWal->hdr.mxFrame+1; 
+          ALWAYS(rc==SQLITE_OK) && iFrame<=iMax; 
+          iFrame++
+      ){
+        /* This call cannot fail. Unless the page for which the page number
+        ** is passed as the second argument is (a) in the cache and 
+        ** (b) has an outstanding reference, then xUndo is either a no-op
+        ** (if (a) is false) or simply expels the page from the cache (if (b)
+        ** is false).
+        **
+        ** If the upper layer is doing a rollback, it is guaranteed that there
+        ** are no outstanding references to any page other than page 1. And
+        ** page 1 is never written to the log until the transaction is
+        ** committed. As a result, the call to xUndo may not fail.
+        */
         assert( pWal->writeLock );
+        assert( pWal->pWiData[walIndexEntry(iFrame)]!=1 );
         rc = xUndo(pUndoCtx, pWal->pWiData[walIndexEntry(iFrame)]);
       }
       walCleanupHash(pWal);
-- 
2.39.5