Simplification to the getAndInitPage() routine that results in improved

performance.

FossilOrigin-Name: 2e9734c2335d8c06fedc9f4cca02baaf326f7fa276bd464f3214f383715a48d6

manifest

@@ -1,5 +1,5 @@
-C Improved\scomment\son\sthe\sgetAndInitPage()\sin\sbtree.c.\s\sNo\scode\schanges.
+C Simplification\sto\sthe\sgetAndInitPage()\sroutine\sthat\sresults\sin\simproved\nperformance.
-D 2023-06-21T21:47:09.597
+D 2023-06-22T01:03:39.798
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -576,7 +576,7 @@ F src/auth.c 19b7ccacae3dfba23fc6f1d0af68134fa216e9040e53b0681b4715445ea030b4
 F src/backup.c 5c97e8023aab1ce14a42387eb3ae00ba5a0644569e3476f38661fa6f824c3523
 F src/bitvec.c 9eac5f42c11914d5ef00a75605bb205e934f435c579687f985f1f8b0995c8645
 F src/btmutex.c 79a43670447eacc651519a429f6ece9fd638563cf95b469d6891185ddae2b522
-F src/btree.c 2ae7a720dc7af3327663ca5a1a4f4131301d040ef6058e1fb2fd5a7c743148d8
+F src/btree.c c0c93b6cb4dc133b528c1290bb4ad0f2414452f9a5758ff2b106af718874f39e
 F src/btree.h aa354b9bad4120af71e214666b35132712b8f2ec11869cb2315c52c81fad45cc
 F src/btreeInt.h 3b4eff7155c0cea6971dc51f62e3529934a15a6640ec607dd42a767e379cb3a9
 F src/build.c a8ae3b32d9aa9bbd2c0e97d7c0dd80def9fbca408425de1608f57ee6f47f45f4
@@ -2041,8 +2041,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 61dfa92b44ad38a7aac76a09e167819ce5d0acace3e06ba9ed17b3264cc043c1
+P dc468cfdb825083b3a4b6cb95c913961e9312e22103c5a0cd923b75c83c65e13
-R 8109896f8dcaf1ac50fc102421edb592
+R 61e892d0fc1ac1905da44ab1762c00e7
 U drh
-Z ee9fa6c5886a3987a472fa73645af4d3
+Z c0e995c2a64328b6123221956a5cefda
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-dc468cfdb825083b3a4b6cb95c913961e9312e22103c5a0cd923b75c83c65e13
+2e9734c2335d8c06fedc9f4cca02baaf326f7fa276bd464f3214f383715a48d6

src/btree.c

@@ -2318,69 +2318,41 @@ Pgno sqlite3BtreeLastPage(Btree *p){
 
 /*
 ** Get a page from the pager and initialize it.
-**
-** If pCur!=0 then the page is being fetched as part of a moveToChild()
-** call.  Do additional sanity checking on the page in this case.
-** And if that additional sanity checking fails, adjust the state of
-** the cursor so that the fetch is effectively "undone".
-**
-** The page is fetched as read-write unless pCur is not NULL and is
-** a read-only cursor.
-**
-** If an error occurs, then *ppPage is undefined. It
-** may remain unchanged, or it may be set to an invalid value.
 */
 static int getAndInitPage(
   BtShared *pBt,                  /* The database file */
   Pgno pgno,                      /* Number of the page to get */
   MemPage **ppPage,               /* Write the page pointer here */
-  BtCursor *pCur,                 /* Cursor to receive the page, or NULL */
   int bReadOnly                   /* True for a read-only page */
 ){
   int rc;
   DbPage *pDbPage;
+  MemPage *pPage;
   assert( sqlite3_mutex_held(pBt->mutex) );
-  assert( pCur==0 || ppPage==&pCur->pPage );
-  assert( pCur==0 || bReadOnly==pCur->curPagerFlags );
-  assert( pCur==0 || pCur->iPage>0 );
 
   if( pgno>btreePagecount(pBt) ){
-    rc = SQLITE_CORRUPT_BKPT;
+    *ppPage = 0;
-    goto getAndInitPage_error1;
+    return SQLITE_CORRUPT_BKPT;
   }
   rc = sqlite3PagerGet(pBt->pPager, pgno, (DbPage**)&pDbPage, bReadOnly);
   if( rc ){
-    goto getAndInitPage_error1;
+    *ppPage = 0;
+    return rc;
   }
-  *ppPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
+  pPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
-  if( (*ppPage)->isInit==0 ){
+  if( pPage->isInit==0 ){
     btreePageFromDbPage(pDbPage, pgno, pBt);
-    rc = btreeInitPage(*ppPage);
+    rc = btreeInitPage(pPage);
     if( rc!=SQLITE_OK ){
-      goto getAndInitPage_error2;
+      releasePage(pPage);
+      *ppPage = 0;
+      return rc;
     }
   }
-  assert( (*ppPage)->pgno==pgno || CORRUPT_DB );
+  assert( pPage->pgno==pgno || CORRUPT_DB );
-  assert( (*ppPage)->aData==sqlite3PagerGetData(pDbPage) );
+  assert( pPage->aData==sqlite3PagerGetData(pDbPage) );
-
+  *ppPage = pPage;
-  /* If obtaining a child page for a cursor, we must verify that the page is
-  ** compatible with the root page. */
-  if( pCur && ((*ppPage)->nCell<1 || (*ppPage)->intKey!=pCur->curIntKey) ){
-    rc = SQLITE_CORRUPT_PGNO(pgno);
-    goto getAndInitPage_error2;
-  }
   return SQLITE_OK;
-
-getAndInitPage_error2:
-  releasePage(*ppPage);
-getAndInitPage_error1:
-  if( pCur ){
-    pCur->iPage--;
-    pCur->pPage = pCur->apPage[pCur->iPage];
-  }
-  testcase( pgno==0 );
-  assert( pgno!=0 || rc!=SQLITE_OK );
-  return rc;
 }
 
 /*
@@ -5354,6 +5326,7 @@ const void *sqlite3BtreePayloadFetch(BtCursor *pCur, u32 *pAmt){
 ** vice-versa).
 */
 static int moveToChild(BtCursor *pCur, u32 newPgno){
+  int rc;
   assert( cursorOwnsBtShared(pCur) );
   assert( pCur->eState==CURSOR_VALID );
   assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
@@ -5367,8 +5340,17 @@ static int moveToChild(BtCursor *pCur, u32 newPgno){
   pCur->apPage[pCur->iPage] = pCur->pPage;
   pCur->ix = 0;
   pCur->iPage++;
-  return getAndInitPage(pCur->pBt, newPgno, &pCur->pPage, pCur,
+  rc = getAndInitPage(pCur->pBt, newPgno, &pCur->pPage, pCur->curPagerFlags);
-                        pCur->curPagerFlags);
+  if( rc==SQLITE_OK
+   && (pCur->pPage->nCell<1 || pCur->pPage->intKey!=pCur->curIntKey)
+  ){
+    releasePage(pCur->pPage);
+    rc = SQLITE_CORRUPT_PGNO(newPgno);
+  }
+  if( rc ){
+    pCur->pPage = pCur->apPage[--pCur->iPage];
+  }
+  return rc;
 }
 
 #ifdef SQLITE_DEBUG
@@ -5475,7 +5457,7 @@ static int moveToRoot(BtCursor *pCur){
       sqlite3BtreeClearCursor(pCur);
     }
     rc = getAndInitPage(pCur->pBt, pCur->pgnoRoot, &pCur->pPage,
-                        0, pCur->curPagerFlags);
+                        pCur->curPagerFlags);
     if( rc!=SQLITE_OK ){
       pCur->eState = CURSOR_INVALID;
       return rc;
@@ -6088,10 +6070,36 @@ bypass_moveto_root:
     }else{
       chldPg = get4byte(findCell(pPage, lwr));
     }
-    pCur->ix = (u16)lwr;
+
-    rc = moveToChild(pCur, chldPg);
+    /* This block is similar to an in-lined version of:
-    if( rc ) break;
+    **
-  }
+    **    pCur->ix = (u16)lwr;
+    **    rc = moveToChild(pCur, chldPg);
+    **    if( rc ) break;
+    */
+    pCur->info.nSize = 0;
+    pCur->curFlags &= ~(BTCF_ValidNKey|BTCF_ValidOvfl);
+    if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+    pCur->aiIdx[pCur->iPage] = (u16)lwr;
+    pCur->apPage[pCur->iPage] = pCur->pPage;
+    pCur->ix = 0;
+    pCur->iPage++;
+    rc = getAndInitPage(pCur->pBt, chldPg, &pCur->pPage, pCur->curPagerFlags);
+    if( rc==SQLITE_OK
+     && (pCur->pPage->nCell<1 || pCur->pPage->intKey!=pCur->curIntKey)
+    ){
+      releasePage(pCur->pPage);
+      rc = SQLITE_CORRUPT_PGNO(chldPg);
+    }
+    if( rc ){
+      pCur->pPage = pCur->apPage[--pCur->iPage];
+      break;
+    }
+    /*
+    ***** End of in-lined moveToChild() call */
+ }
 moveto_index_finish:
   pCur->info.nSize = 0;
   assert( (pCur->curFlags & BTCF_ValidOvfl)==0 );
@@ -8145,7 +8153,7 @@ static int balance_nonroot(
   pgno = get4byte(pRight);
   while( 1 ){
     if( rc==SQLITE_OK ){
-      rc = getAndInitPage(pBt, pgno, &apOld[i], 0, 0);
+      rc = getAndInitPage(pBt, pgno, &apOld[i], 0);
     }
     if( rc ){
       memset(apOld, 0, (i+1)*sizeof(MemPage*));
@@ -10030,7 +10038,7 @@ static int clearDatabasePage(
   if( pgno>btreePagecount(pBt) ){
     return SQLITE_CORRUPT_BKPT;
   }
-  rc = getAndInitPage(pBt, pgno, &pPage, 0, 0);
+  rc = getAndInitPage(pBt, pgno, &pPage, 0);
   if( rc ) return rc;
   if( (pBt->openFlags & BTREE_SINGLE)==0
    && sqlite3PagerPageRefcount(pPage->pDbPage) != (1 + (pgno==1))