From: drh <drh@noemail.net>
Date: Mon, 19 Aug 2013 22:22:41 +0000 (+0000)
Subject: Additional performance improvements in sqlite3BtreeNext() and
X-Git-Tag: version-3.8.1~11^2~17
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=749ced9923571c73f3b965b4143bd924375e280a;p=thirdparty%2Fsqlite.git

Additional performance improvements in sqlite3BtreeNext() and
sqlite3BtreePrevious().

FossilOrigin-Name: 6f99b54aedeb91e46d52f65504d02a9cc61c0062
---

diff --git a/manifest b/manifest
index 3a55a00463..58a5caee72 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\stointeger()\sand\storeal()\sSQL\sfunctions.
-D 2013-08-19T21:15:34.654
+C Additional\sperformance\simprovements\sin\ssqlite3BtreeNext()\sand\nsqlite3BtreePrevious().
+D 2013-08-19T22:22:41.690
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 5e41da95d92656a5004b03d3576e8b226858a28e
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -163,9 +163,9 @@ F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
 F src/backup.c 43b348822db3e4cef48b2ae5a445fbeb6c73a165
 F src/bitvec.c 19a4ba637bd85f8f63fc8c9bae5ade9fb05ec1cb
 F src/btmutex.c 976f45a12e37293e32cae0281b15a21d48a8aaa7
-F src/btree.c 78287b3012fe65fd5e38927d40c01e01a783e016
+F src/btree.c d8cb52cddfe575d91b90d056d91607259f78706b
 F src/btree.h bfe0e8c5759b4ec77b0d18390064a6ef3cdffaaf
-F src/btreeInt.h eecc84f02375b2bb7a44abbcbbe3747dde73edb2
+F src/btreeInt.h 51cf220a9b9223354770883e93a859dc377aa27f
 F src/build.c f99a715ff9290996b579d5e1ec8e94239dc9ae5e
 F src/callback.c d7e46f40c3cf53c43550b7da7a1d0479910b62cc
 F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
@@ -1106,7 +1106,7 @@ F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
 F tool/wherecosttest.c f407dc4c79786982a475261866a161cd007947ae
 F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
-P dc65ad8c4c67b21e3b042b8df6580d02b634a90b dd4b77c82af07bdcc92ed743f050e70887e5956e
-R e3fb50f27097137963de60af3dbc18b8
-U mistachkin
-Z 2bb7e5e3c9622cb177c0d8f0e5a92db1
+P af49707211ff7c7c4d30f4f457631ea8a9fa39eb
+R d86e9a19461f588d02ed145ef81cfebb
+U drh
+Z 1181ebcd03ded8a6c716b64a93881e5c
diff --git a/manifest.uuid b/manifest.uuid
index 7dd17e4566..10a6d51396 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-af49707211ff7c7c4d30f4f457631ea8a9fa39eb
\ No newline at end of file
+6f99b54aedeb91e46d52f65504d02a9cc61c0062
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index bf679cd1f7..d3db676526 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -724,6 +724,9 @@ static int btreeRestoreCursorPosition(BtCursor *pCur){
     sqlite3_free(pCur->pKey);
     pCur->pKey = 0;
     assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_INVALID );
+    if( pCur->skipNext && pCur->eState==CURSOR_VALID ){
+      pCur->eState = CURSOR_SKIPNEXT;
+    }
   }
   return rc;
 }
@@ -749,7 +752,7 @@ int sqlite3BtreeCursorHasMoved(BtCursor *pCur, int *pHasMoved){
     *pHasMoved = 1;
     return rc;
   }
-  if( pCur->eState!=CURSOR_VALID || pCur->skipNext!=0 ){
+  if( pCur->eState!=CURSOR_VALID || NEVER(pCur->skipNext!=0) ){
     *pHasMoved = 1;
   }else{
     *pHasMoved = 0;
@@ -4797,6 +4800,7 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
 
   assert( cursorHoldsMutex(pCur) );
   assert( pRes!=0 );
+  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
   if( pCur->eState!=CURSOR_VALID ){
     rc = restoreCursorPosition(pCur);
     if( rc!=SQLITE_OK ){
@@ -4806,14 +4810,16 @@ int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
       *pRes = 1;
       return SQLITE_OK;
     }
-  }
-  if( pCur->skipNext ){
-    if( pCur->skipNext>0 ){
+    if( pCur->skipNext ){
+      assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT );
+      pCur->eState = CURSOR_VALID;
+      if( pCur->skipNext>0 ){
+        pCur->skipNext = 0;
+        *pRes = 0;
+        return SQLITE_OK;
+      }
       pCur->skipNext = 0;
-      *pRes = 0;
-      return SQLITE_OK;
     }
-    pCur->skipNext = 0;
   }
 
   pPage = pCur->apPage[pCur->iPage];
@@ -4874,6 +4880,8 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
   MemPage *pPage;
 
   assert( cursorHoldsMutex(pCur) );
+  assert( pRes!=0 );
+  assert( pCur->skipNext==0 || pCur->eState!=CURSOR_VALID );
   pCur->atLast = 0;
   if( pCur->eState!=CURSOR_VALID ){
     if( ALWAYS(pCur->eState>=CURSOR_REQUIRESEEK) ){
@@ -4884,14 +4892,16 @@ int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
       *pRes = 1;
       return SQLITE_OK;
     }
-  }
-  if( pCur->skipNext ){
-    if( pCur->skipNext<0 ){
+    if( pCur->skipNext ){
+      assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_SKIPNEXT );
+      pCur->eState = CURSOR_VALID;
+      if( pCur->skipNext<0 ){
+        pCur->skipNext = 0;
+        *pRes = 0;
+        return SQLITE_OK;
+      }
       pCur->skipNext = 0;
-      *pRes = 0;
-      return SQLITE_OK;
     }
-    pCur->skipNext = 0;
   }
 
   pPage = pCur->apPage[pCur->iPage];
diff --git a/src/btreeInt.h b/src/btreeInt.h
index ce3c5493f8..60da24d90c 100644
--- a/src/btreeInt.h
+++ b/src/btreeInt.h
@@ -520,14 +520,19 @@ struct BtCursor {
 /*
 ** Potential values for BtCursor.eState.
 **
-** CURSOR_VALID:
-**   Cursor points to a valid entry. getPayload() etc. may be called.
-**
 ** CURSOR_INVALID:
 **   Cursor does not point to a valid entry. This can happen (for example) 
 **   because the table is empty or because BtreeCursorFirst() has not been
 **   called.
 **
+** CURSOR_VALID:
+**   Cursor points to a valid entry. getPayload() etc. may be called.
+**
+** CURSOR_SKIPNEXT:
+**   Cursor is valid except that the Cursor.skipNext field is non-zero
+**   indicating that the next sqlite3BtreeNext() or sqlite3BtreePrevious()
+**   operation should be a no-op.
+**
 ** CURSOR_REQUIRESEEK:
 **   The table that this cursor was opened on still exists, but has been 
 **   modified since the cursor was last used. The cursor position is saved
@@ -544,8 +549,9 @@ struct BtCursor {
 */
 #define CURSOR_INVALID           0
 #define CURSOR_VALID             1
-#define CURSOR_REQUIRESEEK       2
-#define CURSOR_FAULT             3
+#define CURSOR_SKIPNEXT          2
+#define CURSOR_REQUIRESEEK       3
+#define CURSOR_FAULT             4
 
 /* 
 ** The database page the PENDING_BYTE occupies. This page is never used.