X-Git-Url: https://pd.if.org/git/?p=btree;a=blobdiff_plain;f=threadskv8.c;h=9d17a4a6a99cccb611911c7e6fbb91b36d973e36;hp=91ec929670d8fd4ed6a27cd4fe040f8c9c038ec5;hb=HEAD;hpb=97a2992f299b35ede35012314c35857ff28d174e

diff --git a/threadskv8.c b/threadskv8.c
index 91ec929..9d17a4a 100644
--- a/threadskv8.c
+++ b/threadskv8.c
@@ -112,13 +112,6 @@ typedef struct {
 	ushort serving[1];
 } RWLock;
 
-//	write only queue lock
-
-typedef struct {
-	ushort ticket[1];
-	ushort serving[1];
-} WOLock;
-
 #define PHID 0x1
 #define PRES 0x2
 #define MASK 0x3
@@ -141,6 +134,14 @@ volatile typedef struct {
 #define BOTH 3
 #define SHARE 4
 
+//	write only reentrant lock
+
+typedef struct {
+	BtSpinLatch xcl[1];
+	volatile ushort tid[1];
+	volatile ushort dup[1];
+} WOLock;
+
 //  hash table entries
 
 typedef struct {
@@ -275,6 +276,7 @@ typedef struct {
 	uint latchtotal;			// number of page latch entries
 	uint latchhash;				// number of latch hash table slots
 	uint latchvictim;			// next latch entry to examine
+	ushort thread_no[1];		// next thread number
 	BtHashEntry *hashtable;		// the buffer pool hash table entries
 	BtLatchSet *latchsets;		// mapped latch set from buffer pool
 	unsigned char *pagepool;	// mapped to the buffer pool pages
@@ -294,6 +296,7 @@ typedef struct {
 	int found;				// last delete or insert was found
 	int err;				// last error
 	int reads, writes;		// number of reads and writes from the btree
+	ushort thread_no;		// thread number
 } BtDb;
 
 typedef enum {
@@ -407,29 +410,39 @@ uid bt_newdup (BtDb *bt)
 #endif
 }
 
-//	Write-Only Queue Lock
+void bt_spinreleasewrite(BtSpinLatch *latch);
+void bt_spinwritelock(BtSpinLatch *latch);
 
-void WriteOLock (WOLock *lock)
+//	Write-Only Reentrant Lock
+
+void WriteOLock (WOLock *lock, ushort tid)
 {
-ushort tix;
-#ifdef unix
-	tix = __sync_fetch_and_add (lock->ticket, 1);
-#else
-	tix = _InterlockedExchangeAdd16 (lock->ticket, 1);
-#endif
-	// wait for our ticket to come up
+  while( 1 ) {
+	bt_spinwritelock(lock->xcl);
 
-	while( tix != lock->serving[0] )
-#ifdef unix
-		sched_yield();
-#else
-		SwitchToThread ();
-#endif
+	if( *lock->tid == tid ) {
+		*lock->dup += 1;
+		bt_spinreleasewrite(lock->xcl);
+		return;
+	}
+	if( !*lock->tid ) {
+		*lock->tid = tid;
+		bt_spinreleasewrite(lock->xcl);
+		return;
+	}
+	bt_spinreleasewrite(lock->xcl);
+	sched_yield();
+  }
 }
 
 void WriteORelease (WOLock *lock)
 {
-	lock->serving[0]++;
+	if( *lock->dup ) {
+		*lock->dup -= 1;
+		return;
+	}
+
+	*lock->tid = 0;
 }
 
 //	Phase-Fair reader/writer lock implementation
@@ -1118,6 +1131,11 @@ BtDb *bt = malloc (sizeof(*bt));
 #endif
 	bt->frame = (BtPage)bt->mem;
 	bt->cursor = (BtPage)(bt->mem + 1 * mgr->page_size);
+#ifdef unix
+	bt->thread_no = __sync_fetch_and_add (mgr->thread_no, 1) + 1;
+#else
+	bt->thread_no = _InterlockedIncrement16(mgr->thread_no, 1);
+#endif
 	return bt;
 }
 
@@ -1145,7 +1163,7 @@ int ans;
 
 // place write, read, or parent lock on requested page_no.
 
-void bt_lockpage(BtLock mode, BtLatchSet *latch)
+void bt_lockpage(BtDb *bt, BtLock mode, BtLatchSet *latch)
 {
 	switch( mode ) {
 	case BtLockRead:
@@ -1161,17 +1179,21 @@ void bt_lockpage(BtLock mode, BtLatchSet *latch)
 		WriteLock (latch->access);
 		break;
 	case BtLockParent:
-		WriteOLock (latch->parent);
+		WriteOLock (latch->parent, bt->thread_no);
 		break;
 	case BtLockAtomic:
-		WriteOLock (latch->atomic);
+		WriteOLock (latch->atomic, bt->thread_no);
+		break;
+	case BtLockAtomic | BtLockRead:
+		WriteOLock (latch->atomic, bt->thread_no);
+		ReadLock (latch->readwr);
 		break;
 	}
 }
 
 // remove write, read, or parent lock on requested page
 
-void bt_unlockpage(BtLock mode, BtLatchSet *latch)
+void bt_unlockpage(BtDb *bt, BtLock mode, BtLatchSet *latch)
 {
 	switch( mode ) {
 	case BtLockRead:
@@ -1192,6 +1214,10 @@ void bt_unlockpage(BtLock mode, BtLatchSet *latch)
 	case BtLockAtomic:
 		WriteORelease (latch->atomic);
 		break;
+	case BtLockAtomic | BtLockRead:
+		WriteORelease (latch->atomic);
+		ReadRelease (latch->readwr);
+		break;
 	}
 }
 
@@ -1298,27 +1324,27 @@ uint mode, prevmode;
  	// obtain access lock using lock chaining with Access mode
 
 	if( page_no > ROOT_page )
-	  bt_lockpage(BtLockAccess, set->latch);
+	  bt_lockpage(bt, BtLockAccess, set->latch);
 
 	set->page = bt_mappage (bt, set->latch);
 
 	//	release & unpin parent or left sibling page
 
 	if( prevpage ) {
-	  bt_unlockpage(prevmode, prevlatch);
+	  bt_unlockpage(bt, prevmode, prevlatch);
 	  bt_unpinlatch (prevlatch);
 	  prevpage = 0;
 	}
 
  	// obtain mode lock using lock chaining through AccessLock
 
-	bt_lockpage(mode, set->latch);
+	bt_lockpage(bt, mode, set->latch);
 
 	if( set->page->free )
 		return bt->err = BTERR_struct, 0;
 
 	if( page_no > ROOT_page )
-	  bt_unlockpage(BtLockAccess, set->latch);
+	  bt_unlockpage(bt, BtLockAccess, set->latch);
 
 	// re-read and re-lock root after determining actual level of root
 
@@ -1329,7 +1355,7 @@ uint mode, prevmode;
 		drill = set->page->lvl;
 
 		if( lock != BtLockRead && drill == lvl ) {
-		  bt_unlockpage(mode, set->latch);
+		  bt_unlockpage(bt, mode, set->latch);
 		  bt_unpinlatch (set->latch);
 		  continue;
 		}
@@ -1342,10 +1368,8 @@ uint mode, prevmode;
 	//  find key on page at this level
 	//  and descend to requested level
 
-	if( set->page->kill )
-	  goto slideright;
-
-	if( slot = bt_findslot (set->page, key, len) ) {
+	if( !set->page->kill )
+	 if( slot = bt_findslot (set->page, key, len) ) {
 	  if( drill == lvl )
 		return slot;
 
@@ -1360,13 +1384,11 @@ uint mode, prevmode;
 	  page_no = bt_getid(valptr(set->page, slot)->value);
 	  drill--;
 	  continue;
-	}
+	 }
 
 	//  or slide right into next page
 
-slideright:
 	page_no = bt_getid(set->page->right);
-
   } while( page_no );
 
   // return error on end of right chain
@@ -1393,8 +1415,9 @@ void bt_freepage (BtDb *bt, BtPageSet *set)
 
 	// unlock released page
 
-	bt_unlockpage (BtLockDelete, set->latch);
-	bt_unlockpage (BtLockWrite, set->latch);
+	bt_unlockpage (bt, BtLockDelete, set->latch);
+	bt_unlockpage (bt, BtLockWrite, set->latch);
+	bt_unpinlatch (set->latch);
 
 	// unlock allocation page
 
@@ -1423,8 +1446,8 @@ uint idx;
 	ptr = keyptr(set->page, set->page->cnt);
 	memcpy (leftkey, ptr, ptr->len + sizeof(BtKey));
 
-	bt_lockpage (BtLockParent, set->latch);
-	bt_unlockpage (BtLockWrite, set->latch);
+	bt_lockpage (bt, BtLockParent, set->latch);
+	bt_unlockpage (bt, BtLockWrite, set->latch);
 
 	//	insert new (now smaller) fence key
 
@@ -1441,7 +1464,7 @@ uint idx;
 	if( bt_deletekey (bt, ptr->key, ptr->len, lvl+1) )
 		return bt->err;
 
-	bt_unlockpage (BtLockParent, set->latch);
+	bt_unlockpage (bt, BtLockParent, set->latch);
 	bt_unpinlatch(set->latch);
 	return 0;
 }
@@ -1469,18 +1492,17 @@ uint idx;
 	else
 		return bt->err;
 
-	bt_lockpage (BtLockDelete, child->latch);
-	bt_lockpage (BtLockWrite, child->latch);
+	bt_lockpage (bt, BtLockDelete, child->latch);
+	bt_lockpage (bt, BtLockWrite, child->latch);
 
 	memcpy (root->page, child->page, bt->mgr->page_size);
 	root->latch->dirty = 1;
 
 	bt_freepage (bt, child);
-	bt_unpinlatch (child->latch);
 
   } while( root->page->lvl > 1 && root->page->act == 1 );
 
-  bt_unlockpage (BtLockWrite, root->latch);
+  bt_unlockpage (bt, BtLockWrite, root->latch);
   bt_unpinlatch (root->latch);
   return 0;
 }
@@ -1513,7 +1535,7 @@ BtKey *ptr;
 	else
 		return 0;
 
-	bt_lockpage (BtLockWrite, right->latch);
+	bt_lockpage (bt, BtLockWrite, right->latch);
 
 	// cache copy of key to update
 
@@ -1536,11 +1558,11 @@ BtKey *ptr;
 	right->latch->dirty = 1;
 	right->page->kill = 1;
 
-	bt_lockpage (BtLockParent, right->latch);
-	bt_unlockpage (BtLockWrite, right->latch);
+	bt_lockpage (bt, BtLockParent, right->latch);
+	bt_unlockpage (bt, BtLockWrite, right->latch);
 
-	bt_lockpage (BtLockParent, set->latch);
-	bt_unlockpage (BtLockWrite, set->latch);
+	bt_lockpage (bt, BtLockParent, set->latch);
+	bt_unlockpage (bt, BtLockWrite, set->latch);
 
 	// redirect higher key directly to our new node contents
 
@@ -1559,15 +1581,13 @@ BtKey *ptr;
 
 	//	obtain delete and write locks to right node
 
-	bt_unlockpage (BtLockParent, right->latch);
-	bt_lockpage (BtLockDelete, right->latch);
-	bt_lockpage (BtLockWrite, right->latch);
+	bt_unlockpage (bt, BtLockParent, right->latch);
+	bt_lockpage (bt, BtLockDelete, right->latch);
+	bt_lockpage (bt, BtLockWrite, right->latch);
 	bt_freepage (bt, right);
-	bt_unpinlatch (right->latch);
 
-	bt_unlockpage (BtLockParent, set->latch);
+	bt_unlockpage (bt, BtLockParent, set->latch);
 	bt_unpinlatch (set->latch);
-	bt->found = 1;
 	return 0;
 }
 
@@ -1618,7 +1638,7 @@ BtVal *val;
 	  if( bt_fixfence (bt, set, lvl) )
 		return bt->err;
 	  else
-		return bt->found = found, 0;
+		return 0;
 
 	//	do we need to collapse root?
 
@@ -1626,7 +1646,7 @@ BtVal *val;
 	  if( bt_collapseroot (bt, set) )
 		return bt->err;
 	  else
-		return bt->found = found, 0;
+		return 0;
 
 	//	delete empty page
 
@@ -1634,9 +1654,9 @@ BtVal *val;
 		return bt_deletepage (bt, set);
 
 	set->latch->dirty = 1;
-	bt_unlockpage(BtLockWrite, set->latch);
+	bt_unlockpage(bt, BtLockWrite, set->latch);
 	bt_unpinlatch (set->latch);
-	return bt->found = found, 0;
+	return 0;
 }
 
 BtKey *bt_foundkey (BtDb *bt)
@@ -1666,13 +1686,13 @@ uid page_no;
 
  	// obtain access lock using lock chaining with Access mode
 
-	bt_lockpage(BtLockAccess, set->latch);
+	bt_lockpage(bt, BtLockAccess, set->latch);
 
-	bt_unlockpage(BtLockRead, prevlatch);
+	bt_unlockpage(bt, BtLockRead, prevlatch);
 	bt_unpinlatch (prevlatch);
 
-	bt_lockpage(BtLockRead, set->latch);
-	bt_unlockpage(BtLockAccess, set->latch);
+	bt_lockpage(bt, BtLockRead, set->latch);
+	bt_unlockpage(bt, BtLockAccess, set->latch);
 	return 1;
 }
 
@@ -1730,7 +1750,7 @@ BtVal *val;
 
    } while( slot = bt_findnext (bt, set, slot) );
 
-  bt_unlockpage (BtLockRead, set->latch);
+  bt_unlockpage (bt, BtLockRead, set->latch);
   bt_unpinlatch (set->latch);
   return ret;
 }
@@ -1775,7 +1795,9 @@ BtVal *val;
 	while( cnt++ < max ) {
 		if( cnt == slot )
 			newslot = idx + 2;
-		if( cnt < max && slotptr(bt->frame,cnt)->dead )
+
+		if( cnt < max || bt->frame->lvl )
+		  if( slotptr(bt->frame,cnt)->dead )
 			continue;
 
 		// copy the value across
@@ -1792,11 +1814,9 @@ BtVal *val;
 
 		// make a librarian slot
 
-		if( idx ) {
-			slotptr(page, ++idx)->off = nxt;
-			slotptr(page, idx)->type = Librarian;
-			slotptr(page, idx)->dead = 1;
-		}
+		slotptr(page, ++idx)->off = nxt;
+		slotptr(page, idx)->type = Librarian;
+		slotptr(page, idx)->dead = 1;
 
 		// set up the slot
 
@@ -1886,7 +1906,7 @@ BtVal *val;
 
 	// release and unpin root pages
 
-	bt_unlockpage(BtLockWrite, root->latch);
+	bt_unlockpage(bt, BtLockWrite, root->latch);
 	bt_unpinlatch (root->latch);
 
 	bt_unpinlatch (right);
@@ -1916,8 +1936,10 @@ uint prev;
 	idx = 0;
 
 	while( cnt++ < max ) {
-		if( slotptr(set->page, cnt)->dead && cnt < max )
+		if( cnt < max || set->page->lvl )
+		  if( slotptr(set->page, cnt)->dead )
 			continue;
+
 		src = valptr(set->page, cnt);
 		nxt -= src->len + sizeof(BtVal);
 		memcpy ((unsigned char *)bt->frame + nxt, src, src->len + sizeof(BtVal));
@@ -1929,11 +1951,9 @@ uint prev;
 
 		//	add librarian slot
 
-		if( idx ) {
-			slotptr(bt->frame, ++idx)->off = nxt;
-			slotptr(bt->frame, idx)->type = Librarian;
-			slotptr(bt->frame, idx)->dead = 1;
-		}
+		slotptr(bt->frame, ++idx)->off = nxt;
+		slotptr(bt->frame, idx)->type = Librarian;
+		slotptr(bt->frame, idx)->dead = 1;
 
 		//  add actual slot
 
@@ -1988,11 +2008,9 @@ uint prev;
 
 		//	add librarian slot
 
-		if( idx ) {
-			slotptr(set->page, ++idx)->off = nxt;
-			slotptr(set->page, idx)->type = Librarian;
-			slotptr(set->page, idx)->dead = 1;
-		}
+		slotptr(set->page, ++idx)->off = nxt;
+		slotptr(set->page, idx)->type = Librarian;
+		slotptr(set->page, idx)->dead = 1;
 
 		//	add actual slot
 
@@ -2035,10 +2053,10 @@ BtKey *ptr;
 
 	// insert new fences in their parent pages
 
-	bt_lockpage (BtLockParent, right);
+	bt_lockpage (bt, BtLockParent, right);
 
-	bt_lockpage (BtLockParent, set->latch);
-	bt_unlockpage (BtLockWrite, set->latch);
+	bt_lockpage (bt, BtLockParent, set->latch);
+	bt_unlockpage (bt, BtLockWrite, set->latch);
 
 	// insert new fence for reformulated left block of smaller keys
 
@@ -2056,10 +2074,10 @@ BtKey *ptr;
 	if( bt_insertkey (bt, ptr->key, ptr->len, lvl+1, value, BtId, 1) )
 		return bt->err;
 
-	bt_unlockpage (BtLockParent, set->latch);
+	bt_unlockpage (bt, BtLockParent, set->latch);
 	bt_unpinlatch (set->latch);
 
-	bt_unlockpage (BtLockParent, right);
+	bt_unlockpage (bt, BtLockParent, right);
 	bt_unpinlatch (right);
 	return 0;
 }
@@ -2132,7 +2150,7 @@ BtVal *val;
 	node->dead = 0;
 
 	if( release ) {
-		bt_unlockpage (BtLockWrite, set->latch);
+		bt_unlockpage (bt, BtLockWrite, set->latch);
 		bt_unpinlatch (set->latch);
 	}
 
@@ -2217,7 +2235,7 @@ uint type;
 		slotptr(set->page, slot)->dead = 0;
 		val->len = vallen;
 		memcpy (val->value, value, vallen);
-		bt_unlockpage(BtLockWrite, set->latch);
+		bt_unlockpage(bt, BtLockWrite, set->latch);
 		bt_unpinlatch (set->latch);
 		return 0;
 	}
@@ -2251,7 +2269,7 @@ uint type;
 	ptr->len = keylen;
 	
 	slotptr(set->page, slot)->off = set->page->min;
-	bt_unlockpage(BtLockWrite, set->latch);
+	bt_unlockpage(bt, BtLockWrite, set->latch);
 	bt_unpinlatch (set->latch);
 	return 0;
   }
@@ -2262,7 +2280,7 @@ typedef struct {
 	uint entry;			// latch table entry number
 	uint slot:31;		// page slot number
 	uint reuse:1;		// reused previous page
-} AtomicMod;
+} AtomicTxn;
 
 typedef struct {
 	uid page_no;		// page number for split leaf
@@ -2273,85 +2291,10 @@ typedef struct {
 	unsigned char leafkey[BT_keyarray];
 } AtomicKey;
 
-//  find and load leaf page for given key
-//	leave page Atomic locked and Read locked.
-
-int bt_atomicload (BtDb *bt, BtPageSet *set, unsigned char *key, uint len)
-{
-BtLatchSet *prevlatch;
-uid page_no;
-uint slot;
-
-  //  find level zero page
-
-  if( !(slot = bt_loadpage (bt, set, key, len, 1, BtLockRead)) )
-	return 0;
-
-  // find next non-dead entry on this page
-  //	it will be the fence key if nothing else
-
-  while( slotptr(set->page, slot)->dead )
-	if( slot++ < set->page->cnt )
-	  continue;
-	else
-	  return bt->err = BTERR_struct, 0;
-
-  page_no = bt_getid(valptr(set->page, slot)->value);
-  prevlatch = set->latch;
-
-  while( page_no ) {
-	if( set->latch = bt_pinlatch (bt, page_no, 1) )
-	  set->page = bt_mappage (bt, set->latch);
-	else
-	  return 0;
-
-	if( set->page->free || set->page->lvl )
-		return bt->err = BTERR_struct, 0;
-
- 	// obtain read lock using lock chaining with Access mode
-	//	release & unpin parent/left sibling page
-
-	bt_lockpage(BtLockAccess, set->latch);
-
-	bt_unlockpage(BtLockRead, prevlatch);
-	bt_unpinlatch (prevlatch);
-
-	bt_lockpage(BtLockRead, set->latch);
-	bt_unlockpage(BtLockAccess, set->latch);
-
-	//  find key on page at this level
-	//  and descend to requested level
-
-	if( !set->page->kill )
-	 if( !bt_getid (set->page->right) || keycmp (keyptr(set->page, set->page->cnt), key, len) >= 0 ) {
-	  bt_unlockpage(BtLockRead, set->latch);
-	  bt_lockpage(BtLockAtomic, set->latch);
-	  bt_lockpage(BtLockAccess, set->latch);
-	  bt_lockpage(BtLockRead, set->latch);
-	  bt_unlockpage(BtLockAccess, set->latch);
-
-	  if( slot = bt_findslot (set->page, key, len) )
-		return slot;
-
-	  bt_unlockpage(BtLockAtomic, set->latch);
-	  }
-
-	//  slide right into next page
-
-	page_no = bt_getid(set->page->right);
-	prevlatch = set->latch;
-  }
-
-  // return error on end of right chain
-
-  bt->err = BTERR_struct;
-  return 0;	// return error
-}
-
 //	determine actual page where key is located
 //  return slot number
 
-uint bt_atomicpage (BtDb *bt, BtPage source, AtomicMod *locks, uint src, BtPageSet *set)
+uint bt_atomicpage (BtDb *bt, BtPage source, AtomicTxn *locks, uint src, BtPageSet *set)
 {
 BtKey *key = keyptr(source,src);
 uint slot = locks[src].slot;
@@ -2368,15 +2311,18 @@ uint entry;
 		return slot;
 	}
 
-	//	is locks->reuse set?
-	//	if so, find where our key
-	//	is located on previous page or split pages
+	//	is locks->reuse set? or was slot zeroed?
+	//	if so, find where our key is located 
+	//	on current page or pages split on
+	//	same page txn operations.
 
 	do {
 		set->latch = bt->mgr->latchsets + entry;
 		set->page = bt_mappage (bt, set->latch);
 
 		if( slot = bt_findslot(set->page, key->key, key->len) ) {
+		  if( slotptr(set->page, slot)->type == Librarian )
+			slot++;
 		  if( locks[src].reuse )
 			locks[src].entry = entry;
 		  return slot;
@@ -2387,17 +2333,17 @@ uint entry;
 	return 0;
 }
 
-BTERR bt_atomicinsert (BtDb *bt, BtPage source, AtomicMod *locks, uint src)
+BTERR bt_atomicinsert (BtDb *bt, BtPage source, AtomicTxn *locks, uint src)
 {
 BtKey *key = keyptr(source, src);
 BtVal *val = valptr(source, src);
 BtLatchSet *latch;
 BtPageSet set[1];
-uint entry;
+uint entry, slot;
 
-  while( locks[src].slot = bt_atomicpage (bt, source, locks, src, set) ) {
-	if( locks[src].slot = bt_cleanpage(bt, set, key->len, locks[src].slot, val->len) )
-	  return bt_insertslot (bt, set, locks[src].slot, key->key, key->len, val->value, val->len, slotptr(source,src)->type, 0);
+  while( slot = bt_atomicpage (bt, source, locks, src, set) ) {
+	if( slot = bt_cleanpage(bt, set, key->len, slot, val->len) )
+	  return bt_insertslot (bt, set, slot, key->key, key->len, val->value, val->len, slotptr(source,src)->type, 0);
 
 	if( entry = bt_splitpage (bt, set) )
 	  latch = bt->mgr->latchsets + entry;
@@ -2407,15 +2353,16 @@ uint entry;
 	//	splice right page into split chain
 	//	and WriteLock it.
 
+	bt_lockpage(bt, BtLockWrite, latch);
 	latch->split = set->latch->split;
 	set->latch->split = entry;
-	bt_lockpage(BtLockWrite, latch);
+	locks[src].slot = 0;
   }
 
   return bt->err = BTERR_atomic;
 }
 
-BTERR bt_atomicdelete (BtDb *bt, BtPage source, AtomicMod *locks, uint src)
+BTERR bt_atomicdelete (BtDb *bt, BtPage source, AtomicTxn *locks, uint src)
 {
 BtKey *key = keyptr(source, src);
 uint idx, entry, slot;
@@ -2424,29 +2371,108 @@ BtKey *ptr;
 BtVal *val;
 
 	if( slot = bt_atomicpage (bt, source, locks, src, set) )
+	  ptr = keyptr(set->page, slot);
+	else
+	  return bt->err = BTERR_struct;
+
+	if( !keycmp (ptr, key->key, key->len) )
+	  if( !slotptr(set->page, slot)->dead )
 		slotptr(set->page, slot)->dead = 1;
+	  else
+		return 0;
 	else
-		return bt->err = BTERR_struct;
+		return 0;
 
-	ptr = keyptr(set->page, slot);
 	val = valptr(set->page, slot);
-
 	set->page->garbage += ptr->len + val->len + sizeof(BtKey) + sizeof(BtVal);
 	set->latch->dirty = 1;
  	set->page->act--;
+	bt->found++;
 	return 0;
 }
 
-uint bt_parentmatch (AtomicKey *head, uint entry)
+//	delete an empty master page for a transaction
+
+//	note that the far right page never empties because
+//	it always contains (at least) the infinite stopper key
+//	and that all pages that don't contain any keys are
+//	deleted, or are being held under Atomic lock.
+
+BTERR bt_atomicfree (BtDb *bt, BtPageSet *prev)
 {
-uint cnt = 0;
+BtPageSet right[1], temp[1];
+unsigned char value[BtId];
+uid right_page_no;
+BtKey *ptr;
+
+	bt_lockpage(bt, BtLockWrite, prev->latch);
+
+	//	grab the right sibling
+
+	if( right->latch = bt_pinlatch(bt, bt_getid (prev->page->right), 1) )
+		right->page = bt_mappage (bt, right->latch);
+	else
+		return bt->err;
+
+	bt_lockpage(bt, BtLockAtomic, right->latch);
+	bt_lockpage(bt, BtLockWrite, right->latch);
+
+	//	and pull contents over empty page
+	//	while preserving master's left link
+
+	memcpy (right->page->left, prev->page->left, BtId);
+	memcpy (prev->page, right->page, bt->mgr->page_size);
+
+	//	forward seekers to old right sibling
+	//	to new page location in set
+
+	bt_putid (right->page->right, prev->latch->page_no);
+	right->latch->dirty = 1;
+	right->page->kill = 1;
+
+	//	remove pointer to right page for searchers by
+	//	changing right fence key to point to the master page
+
+	ptr = keyptr(right->page,right->page->cnt);
+	bt_putid (value, prev->latch->page_no);
+
+	if( bt_insertkey (bt, ptr->key, ptr->len, 1, value, BtId, 1) )
+		return bt->err;
+
+	//  now that master page is in good shape we can
+	//	remove its locks.
+
+	bt_unlockpage (bt, BtLockAtomic, prev->latch);
+	bt_unlockpage (bt, BtLockWrite, prev->latch);
+
+	//  fix master's right sibling's left pointer
+	//	to remove scanner's poiner to the right page
+
+	if( right_page_no = bt_getid (prev->page->right) ) {
+	  if( temp->latch = bt_pinlatch (bt, right_page_no, 1) )
+		temp->page = bt_mappage (bt, temp->latch);
+
+	  bt_lockpage (bt, BtLockWrite, temp->latch);
+	  bt_putid (temp->page->left, prev->latch->page_no);
+	  temp->latch->dirty = 1;
+
+	  bt_unlockpage (bt, BtLockWrite, temp->latch);
+	  bt_unpinlatch (temp->latch);
+	} else {	// master is now the far right page
+	  bt_spinwritelock (bt->mgr->lock);
+	  bt_putid (bt->mgr->pagezero->alloc->left, prev->latch->page_no);
+	  bt_spinreleasewrite(bt->mgr->lock);
+	}
 
-	if( head )
-	  do if( head->entry == entry )
-		head->nounlock = 1, cnt++;
-	  while( head = head->next );
+	//	now that there are no pointers to the right page
+	//	we can delete it after the last read access occurs
 
-	return cnt;
+	bt_unlockpage (bt, BtLockWrite, right->latch);
+	bt_unlockpage (bt, BtLockAtomic, right->latch);
+	bt_lockpage (bt, BtLockDelete, right->latch);
+	bt_lockpage (bt, BtLockWrite, right->latch);
+	bt_freepage (bt, right);
+	return 0;
 }
 
 //	atomic modification of a batch of keys.
@@ -2464,7 +2490,7 @@ BtPageSet set[1], prev[1];
 unsigned char value[BtId];
 BtKey *key, *ptr, *key2;
 BtLatchSet *latch;
-AtomicMod *locks;
+AtomicTxn *locks;
 int result = 0;
 BtSlot temp[1];
 BtPage page;
@@ -2472,7 +2498,7 @@ BtVal *val;
 uid right;
 int type;
 
-  locks = calloc (source->cnt + 1, sizeof(AtomicMod));
+  locks = calloc (source->cnt + 1, sizeof(AtomicTxn));
   head = NULL;
   tail = NULL;
 
@@ -2508,11 +2534,11 @@ int type;
 	if( samepage = src > 1 )
 	  if( samepage = !bt_getid(set->page->right) || keycmp (keyptr(set->page, set->page->cnt), key->key, key->len) >= 0 )
 		slot = bt_findslot(set->page, key->key, key->len);
-	  else // release read on previous page
-	 	bt_unlockpage(BtLockRead, set->latch); 
+	  else
+	 	bt_unlockpage(bt, BtLockRead, set->latch); 
 
 	if( !slot )
-	  if( slot = bt_atomicload(bt, set, key->key, key->len) )
+	  if( slot = bt_loadpage(bt, set, key->key, key->len, 0, BtLockRead | BtLockAtomic) )
 		set->latch->split = 0;
 	  else
 		return -1;
@@ -2541,13 +2567,13 @@ int type;
 
 		  // return constraint violation if key already exists
 
-		  bt_unlockpage(BtLockRead, set->latch);
+		  bt_unlockpage(bt, BtLockRead, set->latch);
 		  result = src;
 
 		  while( src ) {
 			if( locks[src].entry ) {
 			  set->latch = bt->mgr->latchsets + locks[src].entry;
-			  bt_unlockpage(BtLockAtomic, set->latch);
+			  bt_unlockpage(bt, BtLockAtomic, set->latch);
 			  bt_unpinlatch (set->latch);
 			}
 			src--;
@@ -2561,8 +2587,8 @@ int type;
 
   //  unlock last loadpage lock
 
-  if( source->cnt > 1 )
-	bt_unlockpage(BtLockRead, set->latch);
+  if( source->cnt )
+	bt_unlockpage(bt, BtLockRead, set->latch);
 
   //  obtain write lock for each master page
 
@@ -2570,7 +2596,7 @@ int type;
 	if( locks[src].reuse )
 	  continue;
 	else
-	  bt_lockpage(BtLockWrite, bt->mgr->latchsets + locks[src].entry);
+	  bt_lockpage(bt, BtLockWrite, bt->mgr->latchsets + locks[src].entry);
 
   // insert or delete each key
   // process any splits or merges
@@ -2613,6 +2639,7 @@ int type;
 	samepage = src;
 
 	//  pick-up all splits from master page
+	//	each one is already WriteLocked.
 
 	entry = prev->latch->split;
 
@@ -2621,14 +2648,15 @@ int type;
 	  set->page = bt_mappage (bt, set->latch);
 	  entry = set->latch->split;
 
-	  // delete empty master page
+	  // delete empty master page by undoing its split
+	  //  (this is potentially another empty page)
+	  //  note that there are no new left pointers yet
 
 	  if( !prev->page->act ) {
 		memcpy (set->page->left, prev->page->left, BtId);
 		memcpy (prev->page, set->page, bt->mgr->page_size);
-		bt_lockpage (BtLockDelete, set->latch);
+		bt_lockpage (bt, BtLockDelete, set->latch);
 		bt_freepage (bt, set);
-		bt_unpinlatch (set->latch);
 
 		prev->latch->dirty = 1;
 		continue;
@@ -2639,9 +2667,8 @@ int type;
 	  if( !set->page->act ) {
 		memcpy (prev->page->right, set->page->right, BtId);
 		prev->latch->split = set->latch->split;
-		bt_lockpage (BtLockDelete, set->latch);
+		bt_lockpage (bt, BtLockDelete, set->latch);
 		bt_freepage (bt, set);
-		bt_unpinlatch (set->latch);
 		continue;
 	  }
 
@@ -2662,9 +2689,11 @@ int type;
 
 	  tail = leaf;
 
+	  // splice in the left link into the split page
+
 	  bt_putid (set->page->left, prev->latch->page_no);
-	  bt_lockpage(BtLockParent, prev->latch);
-	  bt_unlockpage(BtLockWrite, prev->latch);
+	  bt_lockpage(bt, BtLockParent, prev->latch);
+	  bt_unlockpage(bt, BtLockWrite, prev->latch);
 	  *prev = *set;
 	}
 
@@ -2672,19 +2701,19 @@ int type;
 	//	(if all splits were reversed, latch->split == 0)
 
 	if( latch->split ) {
-	  //  fix left pointer in master's original (now split) right sibling
-	  //	or set rightmost page in page zero
+	  //  fix left pointer in master's original (now split)
+	  //  far right sibling or set rightmost page in page zero
 
 	  if( right = bt_getid (prev->page->right) ) {
-		if( set->latch = bt_pinlatch (bt, bt_getid(prev->page->right), 1) )
+		if( set->latch = bt_pinlatch (bt, right, 1) )
 	  	  set->page = bt_mappage (bt, set->latch);
 	 	else
 		  return -1;
 
-	    bt_lockpage (BtLockWrite, set->latch);
+	    bt_lockpage (bt, BtLockWrite, set->latch);
 	    bt_putid (set->page->left, prev->latch->page_no);
 		set->latch->dirty = 1;
-	    bt_unlockpage (BtLockWrite, set->latch);
+	    bt_unlockpage (bt, BtLockWrite, set->latch);
 		bt_unpinlatch (set->latch);
 	  } else {	// prev is rightmost page
 	    bt_spinwritelock (bt->mgr->lock);
@@ -2709,20 +2738,20 @@ int type;
 
 	  tail = leaf;
 
-	  bt_lockpage(BtLockParent, prev->latch);
-	  bt_unlockpage(BtLockWrite, prev->latch);
+	  bt_lockpage(bt, BtLockParent, prev->latch);
+	  bt_unlockpage(bt, BtLockWrite, prev->latch);
 
 	  //  remove atomic lock on master page
 
-	  bt_unlockpage(BtLockAtomic, latch);
+	  bt_unlockpage(bt, BtLockAtomic, latch);
 	  continue;
 	}
 
 	//  finished if prev page occupied (either master or final split)
 
 	if( prev->page->act ) {
-	  bt_unlockpage(BtLockWrite, latch);
-	  bt_unlockpage(BtLockAtomic, latch);
+	  bt_unlockpage(bt, BtLockWrite, latch);
+	  bt_unlockpage(bt, BtLockAtomic, latch);
 	  bt_unpinlatch(latch);
 	  continue;
 	}
@@ -2731,71 +2760,24 @@ int type;
 	// master page located in prev is empty, delete it
 	// by pulling over master's right sibling.
 
-	// Delete empty master's fence key
+	// Remove empty master's fence key
 
 	ptr = keyptr(prev->page,prev->page->cnt);
-	leaf = calloc (sizeof(AtomicKey), 1);
 
-	memcpy (leaf->leafkey, ptr, ptr->len + sizeof(BtKey));
-	leaf->page_no = prev->latch->page_no;
-	leaf->entry = prev->latch->entry;
-	leaf->type = 1;
-  
-	if( tail )
-	  tail->next = leaf;
-	else
-	  head = leaf;
-
-	tail = leaf;
-
-	bt_lockpage(BtLockParent, prev->latch);
-	bt_unlockpage(BtLockWrite, prev->latch);
-
-	// grab master's right sibling
-	//	note that the far right page never empties because
-	//	it always contains (at least) the infinite stopper key
-	//	and that all pages that don't contain any keys have
-	//	been deleted, or are being deleted under write lock.
-
-	if( set->latch = bt_pinlatch(bt, bt_getid (prev->page->right), 1) )
-		set->page = bt_mappage (bt, set->latch);
-	else
+	if( bt_deletekey (bt, ptr->key, ptr->len, 1) )
 		return -1;
 
-	bt_lockpage(BtLockWrite, set->latch);
-
-	//	and pull contents over empty page
-	//	while preserving master's left link
-
-	memcpy (set->page->left, prev->page->left, BtId);
-	memcpy (prev->page, set->page, bt->mgr->page_size);
-
-	//	forward seekers to old right sibling
-	//	to new page location in prev
+	//	perform the remainder of the delete
+	//	from the FIFO queue
 
-	bt_putid (set->page->right, prev->latch->page_no);
-	set->latch->dirty = 1;
-	set->page->kill = 1;
-
-	//	add new fence key for new master page contents, delete
-	//	right sibling after parent posts the new master fence.
-
-	ptr = keyptr(set->page,set->page->cnt);
 	leaf = calloc (sizeof(AtomicKey), 1);
 
 	memcpy (leaf->leafkey, ptr, ptr->len + sizeof(BtKey));
 	leaf->page_no = prev->latch->page_no;
-	leaf->entry = set->latch->entry;
+	leaf->entry = prev->latch->entry;
+	leaf->nounlock = 1;
 	leaf->type = 2;
   
-	//  see if right sibling key update is in the FIFO,
-	//	and ParentLock if not there.
-
-	if( !bt_parentmatch (head, leaf->entry) )
-	  bt_lockpage(BtLockParent, set->latch);
-
-	bt_unlockpage(BtLockWrite, set->latch);
-
 	if( tail )
 	  tail->next = leaf;
 	else
@@ -2803,25 +2785,10 @@ int type;
 
 	tail = leaf;
 
-	//  fix new master's right sibling's left pointer
+	//	leave atomic lock in place until
+	//	deletion completes in next phase.
 
-	if( right = bt_getid (set->page->right) ) {
-	  if( set->latch = bt_pinlatch (bt, right, 1) )
-		set->page = bt_mappage (bt, set->latch);
-
-	  bt_lockpage (BtLockWrite, set->latch);
-	  bt_putid (set->page->left, prev->latch->page_no);
-	  set->latch->dirty = 1;
-
-	  bt_unlockpage (BtLockWrite, set->latch);
-	  bt_unpinlatch (set->latch);
-	} else {	// master is now the far right page
-	  bt_spinwritelock (bt->mgr->lock);
-	  bt_putid (bt->mgr->pagezero->alloc->left, prev->latch->page_no);
-	  bt_spinreleasewrite(bt->mgr->lock);
-	}
-
-	bt_unlockpage(BtLockAtomic, latch);
+	bt_unlockpage(bt, BtLockWrite, prev->latch);
   }
   
   //  add & delete keys for any pages split or merged during transaction
@@ -2847,18 +2814,15 @@ int type;
 
 		break;
 
-	  case 2:	// insert key & free
-	    if( bt_insertkey (bt, ptr->key, ptr->len, 1, value, BtId, 1) )
+	  case 2:	// free page
+		if( bt_atomicfree (bt, set) )
 		  return -1;
 
-		bt_lockpage (BtLockDelete, set->latch);
-		bt_lockpage (BtLockWrite, set->latch);
-		bt_freepage (bt, set);
 		break;
 	  }
 
 	  if( !leaf->nounlock )
-	    bt_unlockpage (BtLockParent, set->latch);
+	    bt_unlockpage (bt, BtLockParent, set->latch);
 
 	  bt_unpinlatch (set->latch);
 	  tail = leaf->next;
@@ -2883,9 +2847,9 @@ BtPageSet set[1];
 	else
 		return 0;
 
-    bt_lockpage(BtLockRead, set->latch);
+    bt_lockpage(bt, BtLockRead, set->latch);
 	memcpy (bt->cursor, set->page, bt->mgr->page_size);
-    bt_unlockpage(BtLockRead, set->latch);
+    bt_unlockpage(bt, BtLockRead, set->latch);
 	bt_unpinlatch (set->latch);
 
 	bt->cursor_page = page_no;
@@ -2916,9 +2880,9 @@ findourself:
 	else
 		return 0;
 
-    bt_lockpage(BtLockRead, set->latch);
+    bt_lockpage(bt, BtLockRead, set->latch);
 	memcpy (bt->cursor, set->page, bt->mgr->page_size);
-	bt_unlockpage(BtLockRead, set->latch);
+	bt_unlockpage(bt, BtLockRead, set->latch);
 	bt_unpinlatch (set->latch);
 	
 	next = bt_getid (bt->cursor->right);
@@ -2964,11 +2928,11 @@ uid right;
 	else
 		return 0;
 
-    bt_lockpage(BtLockRead, set->latch);
+    bt_lockpage(bt, BtLockRead, set->latch);
 
 	memcpy (bt->cursor, set->page, bt->mgr->page_size);
 
-	bt_unlockpage(BtLockRead, set->latch);
+	bt_unlockpage(bt, BtLockRead, set->latch);
 	bt_unpinlatch (set->latch);
 	slot = 0;
 
@@ -2993,7 +2957,7 @@ uint slot;
 
 	bt->cursor_page = set->latch->page_no;
 
-	bt_unlockpage(BtLockRead, set->latch);
+	bt_unlockpage(bt, BtLockRead, set->latch);
 	bt_unpinlatch (set->latch);
 	return slot;
 }
@@ -3087,7 +3051,7 @@ uint slot = 0;
 			fprintf(stderr, "latchset %d accesslocked for page %.8x\n", slot, latch->page_no);
 		memset ((ushort *)latch->access, 0, sizeof(RWLock));
 
-		if( *latch->parent->ticket != *latch->parent->serving )
+		if( *latch->parent->tid )
 			fprintf(stderr, "latchset %d parentlocked for page %.8x\n", slot, latch->page_no);
 		memset ((ushort *)latch->parent, 0, sizeof(RWLock));
 
@@ -3120,9 +3084,9 @@ BtKey *ptr;
 			fprintf(stderr, "latchset %d accesslocked for page %.8x\n", idx, latch->page_no);
 		memset ((ushort *)latch->access, 0, sizeof(RWLock));
 
-		if( *latch->parent->ticket != *latch->parent->serving )
+		if( *latch->parent->tid )
 			fprintf(stderr, "latchset %d parentlocked for page %.8x\n", idx, latch->page_no);
-		memset ((ushort *)latch->parent, 0, sizeof(RWLock));
+		memset ((ushort *)latch->parent, 0, sizeof(WOLock));
 
 		if( latch->pin ) {
 			fprintf(stderr, "latchset %d pinned for page %.8x\n", idx, latch->page_no);
@@ -3277,7 +3241,7 @@ FILE *in;
 			}
 			else if( len < BT_maxkey )
 				key[len++] = ch;
-		fprintf(stderr, "finished %s for %d keys: %d reads %d writes\n", args->infile, line, bt->reads, bt->writes);
+		fprintf(stderr, "finished %s for %d keys: %d reads %d writes %d found\n", args->infile, line, bt->reads, bt->writes, bt->found);
 		break;
 
 	case 'w':
@@ -3322,7 +3286,7 @@ FILE *in;
 				set->page = bt_mappage (bt, set->latch);
 			else
 				fprintf(stderr, "unable to obtain latch"), exit(1);
-			bt_lockpage (BtLockRead, set->latch);
+			bt_lockpage (bt, BtLockRead, set->latch);
 			next = bt_getid (set->page->right);
 
 			for( slot = 0; slot++ < set->page->cnt; )
@@ -3341,7 +3305,7 @@ FILE *in;
 				cnt++;
 			   }
 
-			bt_unlockpage (BtLockRead, set->latch);
+			bt_unlockpage (bt, BtLockRead, set->latch);
 			bt_unpinlatch (set->latch);
 	  	} while( page_no = next );