Simplify the b-tree logic by taking advantage of the fact that all b-trees

are either intkey+leafdata or zerodata. (CVS 5431)

FossilOrigin-Name: 29d3bfd7c9a68078385354394052612bf812859b

manifest

@@ -1,5 +1,5 @@
-C Fix\sthe\stest\sharness\sso\sthat\sit\sdoes\snot\stry\sto\slink\sagainst\nsqlite3_mutex_alloc()\sif\scompiled\swith\s-DSQLITE_THREADSAFE=0.\s(CVS\s5430)
-D 2008-07-17T17:34:20
+C Simplify\sthe\sb-tree\slogic\sby\staking\sadvantage\sof\sthe\sfact\sthat\sall\sb-trees\nare\seither\sintkey+leafdata\sor\szerodata.\s(CVS\s5431)
+D 2008-07-17T18:39:58
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in a03f7cb4f7ad50bc53a788c6c544430e81f95de4
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -96,9 +96,9 @@ F src/attach.c b18ba42c77f7d3941f5d23d2ca20fa1d841a4e91
 F src/auth.c c8b2ab5c8bad4bd90ed7c294694f48269162c627
 F src/bitvec.c 95c86bd18d8fedf0533f5af196192546e10a7e7d
 F src/btmutex.c 709cad2cdca0afd013f0f612363810e53f59ec53
-F src/btree.c 5dcc47a35d12bc8584d7c89ed113d24fb9fbc2ca
+F src/btree.c c618d62fb41642216f8fc5be403c36f32e1b25d6
 F src/btree.h 03256ed7ee42b5ecacbe887070b0f8249e7d069d
-F src/btreeInt.h a6a5ffab12fa2c15392b85242cd5568371949046
+F src/btreeInt.h 2aa6dc53b1801bb22815a5be22e03be121f3bd8f
 F src/build.c bac7233d984be3805aaa41cf500f7ee12dc97249
 F src/callback.c aa492a0ad8c2d454edff9fb8a57fae13743cf71d
 F src/complete.c cb14e06dbe79dee031031f0d9e686ff306afe07c
@@ -608,7 +608,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 1dbced29de5f59ba2ebf877edcadf171540374d1
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P 08fe49f62f8a91c36ad4bb9a1d8c89806c37f600
-R 514cbf07ace43083faff0e77954a2fe0
+P 26a203d894edd0091ac60862956e42d22167011e
+R 0aa24510df7c6bac75839ea22cde6884
 U drh
-Z 0a72bbba17dc41aabdaed96d70dac8a1
+Z 2661cde038f2c435549bd085c583b89a

manifest.uuid

@@ -1 +1 @@
-26a203d894edd0091ac60862956e42d22167011e
+29d3bfd7c9a68078385354394052612bf812859b

src/btree.c

@@ -9,7 +9,7 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** $Id: btree.c,v 1.483 2008/07/16 18:17:56 danielk1977 Exp $
+** $Id: btree.c,v 1.484 2008/07/17 18:39:58 drh Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** See the header comment on "btreeInt.h" for additional information.
@@ -871,27 +871,38 @@ static void freeSpace(MemPage *pPage, int start, int size){
 /*
 ** Decode the flags byte (the first byte of the header) for a page
 ** and initialize fields of the MemPage structure accordingly.
+**
+** Only the following combinations are supported.  Anything different
+** indicates a corrupt database files:
+**
+**         PTF_ZERODATA
+**         PTF_ZERODATA | PTF_LEAF
+**         PTF_LEAFDATA | PTF_INTKEY
+**         PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF
 */
-static void decodeFlags(MemPage *pPage, int flagByte){
+static int decodeFlags(MemPage *pPage, int flagByte){
   BtShared *pBt;     /* A copy of pPage->pBt */
 
   assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
   assert( sqlite3_mutex_held(pPage->pBt->mutex) );
-  pPage->intKey = (flagByte & (PTF_INTKEY|PTF_LEAFDATA))!=0;
-  pPage->zeroData = (flagByte & PTF_ZERODATA)!=0;
-  pPage->leaf = (flagByte & PTF_LEAF)!=0;
-  pPage->childPtrSize = 4*(pPage->leaf==0);
+  pPage->leaf = flagByte>>3;  assert( PTF_LEAF == 1<<3 );
+  flagByte &= ~PTF_LEAF;
+  pPage->childPtrSize = 4-4*pPage->leaf;
   pBt = pPage->pBt;
-  if( flagByte & PTF_LEAFDATA ){
-    pPage->leafData = 1;
+  if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
+    pPage->intKey = 1;
+    pPage->hasData = pPage->leaf;
     pPage->maxLocal = pBt->maxLeaf;
     pPage->minLocal = pBt->minLeaf;
-  }else{
-    pPage->leafData = 0;
+  }else if( flagByte==PTF_ZERODATA ){
+    pPage->intKey = 0;
+    pPage->hasData = 0;
     pPage->maxLocal = pBt->maxLocal;
     pPage->minLocal = pBt->minLocal;
+  }else{
+    return SQLITE_CORRUPT_BKPT;
   }
-  pPage->hasData = !(pPage->zeroData || (!pPage->leaf && pPage->leafData));
+  return SQLITE_OK;
 }
 
 /*
@@ -941,7 +952,7 @@ int sqlite3BtreeInitPage(
   }
   hdr = pPage->hdrOffset;
   data = pPage->aData;
-  decodeFlags(pPage, data[hdr]);
+  if( decodeFlags(pPage, data[hdr]) ) return SQLITE_CORRUPT_BKPT;
   pPage->nOverflow = 0;
   pPage->idxShift = 0;
   usableSize = pBt->usableSize;
@@ -3757,7 +3768,7 @@ int sqlite3BtreeMoveto(
       }
       if( c==0 ){
         pCur->info.nKey = nCellKey;
-        if( pPage->leafData && !pPage->leaf ){
+        if( pPage->intKey && !pPage->leaf ){
           lwr = pCur->idx;
           upr = lwr - 1;
           break;
@@ -3884,7 +3895,7 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
       pPage = pCur->pPage;
     }while( pCur->idx>=pPage->nCell );
     *pRes = 0;
-    if( pPage->leafData ){
+    if( pPage->intKey ){
       rc = sqlite3BtreeNext(pCur, pRes);
     }else{
       rc = SQLITE_OK;
@@ -3951,7 +3962,7 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
     pCur->idx--;
     pCur->info.nSize = 0;
     pCur->validNKey = 0;
-    if( pPage->leafData && !pPage->leaf ){
+    if( pPage->intKey && !pPage->leaf ){
       rc = sqlite3BtreePrevious(pCur, pRes);
     }else{
       rc = SQLITE_OK;
@@ -4946,12 +4957,12 @@ static int balance_nonroot(MemPage *pPage){
   */
   if( pPage->leaf &&
       pPage->intKey &&
-      pPage->leafData &&
       pPage->nOverflow==1 &&
       pPage->aOvfl[0].idx==pPage->nCell &&
       pPage->pParent->pgno!=1 &&
       get4byte(&pParent->aData[pParent->hdrOffset+8])==pPage->pgno
   ){
+    assert( pPage->intKey );
     /*
     ** TODO: Check the siblings to the left of pPage. It may be that
     ** they are not full and no new page is required.
@@ -5095,7 +5106,7 @@ static int balance_nonroot(MemPage *pPage){
   */
   nCell = 0;
   leafCorrection = pPage->leaf*4;
-  leafData = pPage->leafData && pPage->leaf;
+  leafData = pPage->hasData;
   for(i=0; i<nOld; i++){
     MemPage *pOld = apCopy[i];
     int limit = pOld->nCell+pOld->nOverflow;
@@ -5772,7 +5783,7 @@ int sqlite3BtreeInsert(
 
   pPage = pCur->pPage;
   assert( pPage->intKey || nKey>=0 );
-  assert( pPage->leaf || !pPage->leafData );
+  assert( pPage->leaf || !pPage->intKey );
   TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
           pCur->pgnoRoot, nKey, nData, pPage->pgno,
           loc==0 ? "overwrite" : "new entry"));
@@ -5888,7 +5899,7 @@ int sqlite3BtreeDelete(BtCursor *pCur){
     unsigned char *pNext;
     int notUsed;
     unsigned char *tempCell = 0;
-    assert( !pPage->leafData );
+    assert( !pPage->intKey );
     sqlite3BtreeGetTempCursor(pCur, &leafCur);
     rc = sqlite3BtreeNext(&leafCur, &notUsed);
     if( rc==SQLITE_OK ){

src/btreeInt.h

@@ -9,7 +9,7 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** $Id: btreeInt.h,v 1.26 2008/07/12 14:52:20 drh Exp $
+** $Id: btreeInt.h,v 1.27 2008/07/17 18:39:58 drh Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** For a detailed discussion of BTrees, refer to
@@ -275,8 +275,6 @@ struct MemPage {
   u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
   u8 intKey;           /* True if intkey flag is set */
   u8 leaf;             /* True if leaf flag is set */
-  u8 zeroData;         /* True if table stores keys only */
-  u8 leafData;         /* True if tables stores data on leaves only */
   u8 hasData;          /* True if this page stores data */
   u8 hdrOffset;        /* 100 for page 1.  0 otherwise */
   u8 childPtrSize;     /* 0 if leaf==1.  4 if leaf==0 */