Make bt_splitpage more conservative wrt posting fence keys

[btree] / threads2h.c

diff --git a/threads2h.c b/threads2h.c
index 46742c487497d05185dd795028a54aadb46ff4db..4a28044811ef815c490558f5cf66af89d13c29aa 100644 (file)
--- a/threads2h.c
+++ b/threads2h.c
@@ -170,10 +170,9 @@ typedef struct BtPage_ {
        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 killed
        unsigned char dirty:1;          // page has deleted keys
-       unsigned char posted:1;         // page fence is posted
        unsigned char right[BtId];      // page number to right
 } *BtPage;
 
@@ -1964,10 +1963,10 @@ uid left;
 BTERR bt_splitpage (BtDb *bt, BtPageSet *set)
 {
 uint cnt = 0, idx = 0, max, nxt = bt->mgr->page_size;
-unsigned char fencekey[256];
+unsigned char fencekey[256], rightkey[256];
 uint lvl = set->page->lvl;
+BtPageSet right[1];
 uint prev;
-uid right;
 BtKey key;
 
        //  split higher half of keys to bt->frame
@@ -1989,6 +1988,10 @@ BtKey key;
                slotptr(bt->frame, idx)->off = nxt;
        }
 
+       // remember existing fence key for new page to the right
+
+       memcpy (rightkey, key, key->len + 1);
+
        bt->frame->bits = bt->mgr->page_bits;
        bt->frame->min = nxt;
        bt->frame->cnt = idx;
@@ -2001,7 +2004,7 @@ BtKey key;
 
        //      get new free page and write higher keys to it.
 
-       if( !(right = bt_newpage(bt, bt->frame)) )
+       if( !(right->page_no = bt_newpage(bt, bt->frame)) )
                return bt->err;
 
        //      update lower keys to continue in old page
@@ -2009,7 +2012,6 @@ BtKey key;
        memcpy (bt->frame, set->page, bt->mgr->page_size);
        memset (set->page+1, 0, bt->mgr->page_size - sizeof(*set->page));
        nxt = bt->mgr->page_size;
-       set->page->posted = 0;
        set->page->dirty = 0;
        set->page->act = 0;
        cnt = 0;
@@ -2030,62 +2032,40 @@ BtKey key;
        // remember fence key for smaller page
 
        memcpy(fencekey, key, key->len + 1);
-       bt_putid(set->page->right, right);
+
+       bt_putid(set->page->right, right->page_no);
        set->page->min = nxt;
        set->page->cnt = idx;
 
        // if current page is the root page, split it
 
        if( set->page_no == ROOT_page )
-               return bt_splitroot (bt, set, fencekey, right);
-
-       right = 0;
+               return bt_splitroot (bt, set, fencekey, right->page_no);
 
        // insert new fences in their parent pages
 
-       while( 1 ) {
-               bt_lockpage (BtLockParent, set->latch);
-
-               key = keyptr (set->page, set->page->cnt);
-               memcpy (fencekey, key, key->len + 1);
-               prev = set->page->posted;
-
-               if( right && prev ) {
-                       bt_unlockpage (BtLockParent, set->latch);
-                       bt_unlockpage (BtLockWrite, set->latch);
-                       bt_unpinlatch (set->latch);
-                       bt_unpinpool (set->pool);
-                       return 0;
-               }
-
-               right = bt_getid (set->page->right);
-               set->page->posted = 1;
-
-               bt_unlockpage (BtLockWrite, set->latch);
-
-               // insert new fence for reformulated left block of smaller keys
+       right->latch = bt_pinlatch (bt, right->page_no);
+       bt_lockpage (BtLockParent, right->latch);
 
-               if( !prev )
-                 if( bt_insertkey (bt, fencekey+1, *fencekey, lvl+1, set->page_no, time(NULL)) )
-                       return bt->err;
+       bt_lockpage (BtLockParent, set->latch);
+       bt_unlockpage (BtLockWrite, set->latch);
 
-               bt_unlockpage (BtLockParent, set->latch);
-               bt_unpinlatch (set->latch);
-               bt_unpinpool (set->pool);
+       // insert new fence for reformulated left block of smaller keys
 
-               if( !(set->page_no = right) )
-                       break;
+       if( bt_insertkey (bt, fencekey+1, *fencekey, lvl+1, set->page_no, time(NULL)) )
+               return bt->err;
 
-               set->latch = bt_pinlatch (bt, right);
+       // switch fence for right block of larger keys to new right page
 
-               if( set->pool = bt_pinpool (bt, right) )
-                       set->page = bt_page (bt, set->pool, right);
-               else
-                       return bt->err;
+       if( bt_insertkey (bt, rightkey+1, *rightkey, lvl+1, right->page_no, time(NULL)) )
+               return bt->err;
 
-               bt_lockpage (BtLockWrite, set->latch);
-       }
+       bt_unlockpage (BtLockParent, set->latch);
+       bt_unpinlatch (set->latch);
+       bt_unpinpool (set->pool);
 
+       bt_unlockpage (BtLockParent, right->latch);
+       bt_unpinlatch (right->latch);
        return 0;
 }