Simplifications and comment enhancements on btree.c. (CVS 6925)

FossilOrigin-Name: 5ba880dde8a219543ced6f792c7f9ecdcd8c1cbb

manifest

@@ -1,5 +1,5 @@
-C Modify\smksqlite3c.tcl\sso\sthat\sit\sinserts\sSQLITE_API\smacros\sinto\ssqlite3.h.\sTicket\s#3983.\s(CVS\s6924)
-D 2009-07-22T18:24:54
+C Simplifications\sand\scomment\senhancements\son\sbtree.c.\s(CVS\s6925)
+D 2009-07-23T01:44:00
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in df9359da7a726ccb67a45db905c5447d5c00c6ef
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -106,7 +106,7 @@ F src/auth.c 802a9439dfa0b8c208b10055cba400e82ef18025
 F src/backup.c 6f1c2d9862c8a3feb7739dfcca02c1f5352e37f3
 F src/bitvec.c cfbf6af5b0ababb4f06ed3e75c616dadaf47fcbd
 F src/btmutex.c 0f43a75bb5b8147b386e8e1c3e71ba734e3863b7
-F src/btree.c e3cd5ed99cdf946d9e95dd88dd09647746e472f5
+F src/btree.c 64fbba1140bb06edbac2553cfd339145bbdc2665
 F src/btree.h 577448a890c2ab9b21e6ab74f073526184bceebe
 F src/btreeInt.h 1c86297e69380f6577e7ae67452597dd8d5c2705
 F src/build.c 867028ee9f63f7bc8eb8d4a720bb98cf9b9a12b4
@@ -741,7 +741,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl 672f81d693a03f80f5ae60bfefacd8a349e76746
-P 375fd6f9c54fa5aa8cfae30845c7bfc0ec49e8fa
-R f2c5a9364fc57c0663cfd0bb1d794a61
-U danielk1977
-Z b281c46d3b56ab640d5620716ac447c6
+P 803ec79f3b05fdd680f9ab762685bbd50a087b9b
+R 1af5efb9239298a70b679f6a0b5afcda
+U drh
+Z 203e36635efa708168ec055bebd9cda7

manifest.uuid

@@ -1 +1 @@
-803ec79f3b05fdd680f9ab762685bbd50a087b9b
+5ba880dde8a219543ced6f792c7f9ecdcd8c1cbb

src/btree.c

@@ -9,7 +9,7 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** $Id: btree.c,v 1.700 2009/07/22 18:07:41 drh Exp $
+** $Id: btree.c,v 1.701 2009/07/23 01:44:00 drh Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** See the header comment on "btreeInt.h" for additional information.
@@ -2315,8 +2315,9 @@ static void unlockBtreeIfUnused(BtShared *pBt){
 }
 
 /*
-** Create a new database by initializing the first page of the
-** file.
+** If pBt points to an empty file then convert that empty file
+** into a new empty database by initializing the first page of
+** the database.
 */
 static int newDatabase(BtShared *pBt){
   MemPage *pP1;
@@ -2325,8 +2326,11 @@ static int newDatabase(BtShared *pBt){
   int nPage;
 
   assert( sqlite3_mutex_held(pBt->mutex) );
+  /* The database size has already been measured and cached, so failure
+  ** is impossible here.  If the original size measurement failed, then
+  ** processing aborts before entering this routine. */
   rc = sqlite3PagerPagecount(pBt->pPager, &nPage);
-  if( rc!=SQLITE_OK || nPage>0 ){
+  if( NEVER(rc!=SQLITE_OK) || nPage>0 ){
     return rc;
   }
   pP1 = pBt->pPage1;