Make bt_splitpage more conservative wrt posting fence keys

[btree] / btree2s.c

diff --git a/btree2s.c b/btree2s.c
index 586dea7c2034183cdc5b8164ae4039be7e13a9eb..49b910961e8240139eabe622717f61a2f2daab0b 100644 (file)
--- a/btree2s.c
+++ b/btree2s.c
@@ -121,10 +121,9 @@ typedef struct {
        uint min;                                       // next key offset
        unsigned char bits:7;           // page size in bits
        unsigned char free:1;           // page is on free list
-       unsigned char lvl:5;            // level of page
+       unsigned char lvl:6;            // level of page
        unsigned char kill:1;           // page is being deleted
        unsigned char dirty:1;          // page is dirty
-       unsigned char posted:1;         // page is posted in parent
        unsigned char right[BtId];      // page number to right
 } *BtPage;
 
@@ -1500,11 +1499,10 @@ uid right;
 BTERR bt_splitpage (BtDb *bt)
 {
 uint cnt = 0, idx = 0, max, nxt = bt->page_size;
+unsigned char fencekey[256], rightkey[256];
 uid page_no = bt->page_no, right;
-unsigned char fencekey[256];
 BtPage page = bt->page;
 uint lvl = page->lvl;
-uint prev;
 BtKey key;
 
        //  split higher half of keys to bt->frame
@@ -1526,6 +1524,10 @@ BtKey key;
                slotptr(bt->frame, idx)->off = nxt;
        }
 
+       //      remember fence key for new right page
+
+       memcpy (rightkey, key, key->len + 1);
+
        bt->frame->bits = bt->page_bits;
        bt->frame->min = nxt;
        bt->frame->cnt = idx;
@@ -1546,7 +1548,6 @@ BtKey key;
        memcpy (bt->frame, page, bt->page_size);
        memset (page+1, 0, bt->page_size - sizeof(*page));
        nxt = bt->page_size;
-       page->posted = 0;
        page->dirty = 0;
        page->act = 0;
        cnt = 0;
@@ -1568,6 +1569,7 @@ BtKey key;
        // remember fence key for smaller page
 
        memcpy (fencekey, key, key->len + 1);
+
        bt_putid(page->right, right);
        page->min = nxt;
        page->cnt = idx;
@@ -1577,59 +1579,33 @@ BtKey key;
        if( page_no == ROOT_page )
                return bt_splitroot (bt, fencekey, right);
 
-       // update left (containing) node
+       //      lock right page
 
-       if( bt_update(bt, page, page_no) )
+       if( bt_lockpage (bt, right, BtLockParent) )
                return bt->err;
 
-       right = 0;
-
-       //  insert new fences in parent pages
+       // update left (containing) node
 
-       while( 1 ) {
-         if( bt_lockpage (bt, page_no, BtLockParent) )
+       if( bt_update(bt, page, page_no) )
                return bt->err;
 
-         if( right )
-          if( bt_mappage (bt, &bt->page, page_no) )
+       if( bt_lockpage (bt, page_no, BtLockParent) )
                return bt->err;
 
-         key = keyptr(bt->page, bt->page->cnt);
-         memcpy (fencekey, key, key->len + 1);
-         prev = bt->page->posted;
-
-         if( right && prev ) {
-               if( bt_unlockpage (bt, page_no, BtLockParent) )
-                 return bt->err;
-               return bt_unlockpage (bt, page_no, BtLockWrite);
-         }
-
-         right = bt_getid (bt->page->right);
-         bt->page->posted = 1;
+       // insert new fence for reformulated left block
 
-         if( bt_update (bt, bt->page, page_no) )
+       if( bt_insertkey (bt, fencekey+1, *fencekey, lvl+1, page_no, time(NULL)) )
                return bt->err;
 
-         if( bt_unlockpage (bt, page_no, BtLockWrite) )
-               return bt->err;
-
-         // insert new fence for reformulated left block
-
-         if( !prev )
-          if( bt_insertkey (bt, fencekey+1, *fencekey, lvl + 1, page_no, time(NULL)) )
-               return bt->err;
+       //      switch fence for right block of larger keys to new right page
 
-         if( bt_unlockpage (bt, page_no, BtLockParent) )
+       if( bt_insertkey (bt, rightkey+1, *rightkey, lvl+1, right, time(NULL)) )
                return bt->err;
 
-         if( !(page_no = right) )
-               break;
-
-         if( bt_lockpage (bt, page_no, BtLockWrite) )
+       if( bt_unlockpage (bt, page_no, BtLockParent) )
                return bt->err;
-       }
 
-       return 0;
+       return bt_unlockpage (bt, right, BtLockParent);
 }
 
 //  Insert new key into the btree at requested level.