X-Git-Url: https://pd.if.org/git/?p=btree;a=blobdiff_plain;f=btree2s.c;h=19ad3beb64436ce60d78a7e03327f2c2c06895cc;hp=ac7673e75cca8a0c1a9debe608f938163dfa99d0;hb=392e5f08cc164c87e56153aa78a740f93325750e;hpb=c0d1fd8ff9f39147bdda132d5e8725b9bcfe2a9a

diff --git a/btree2s.c b/btree2s.c
index ac7673e..19ad3be 100644
--- a/btree2s.c
+++ b/btree2s.c
@@ -1,5 +1,6 @@
 // btree version 2s
-// 02 FEB 2014
+//	with reworked bt_deletekey code
+// 25 FEB 2014
 
 // author: karl malbrain, malbrain@cal.berkeley.edu
 
@@ -119,8 +120,10 @@ typedef struct {
 	uint cnt;					// count of keys in page
 	uint act;					// count of active keys
 	uint min;					// next key offset
-	unsigned char bits;			// page size in bits
-	unsigned char lvl:7;		// level of page
+	unsigned char bits:7;		// page size in bits
+	unsigned char free:1;		// page is on free list
+	unsigned char lvl:6;		// level of page
+	unsigned char kill:1;		// page is being deleted
 	unsigned char dirty:1;		// page is dirty
 	unsigned char right[BtId];	// page number to right
 } *BtPage;
@@ -166,9 +169,7 @@ typedef struct _BtDb {
 	int nodemax;		// highest page cache segment allocated
 	int hashmask;		// number of pages in segments - 1
 	int hashsize;		// size of hash table
-	int posted;			// last loadpage found posted key
 	int found;			// last deletekey found key
-	int fence;			// last load page used fence position
 	BtHash *lrufirst;	// lru list head
 	BtHash *lrulast;	// lru list tail
 	ushort *cache;		// hash table for cached segments
@@ -396,7 +397,7 @@ BtHash *hash;
 		do munmap (hash->page, (bt->hashmask+1) << bt->page_bits);
 		while(hash = hash->lrunext);
 
-	if ( bt->mem )
+	if( bt->mem )
 		free (bt->mem);
 	close (bt->idx);
 	free (bt->cache);
@@ -410,7 +411,7 @@ BtHash *hash;
 		CloseHandle(hash->hmap);
 	  } while(hash = hash->lrunext);
 
-	if ( bt->mem)
+	if( bt->mem)
 		VirtualFree (bt->mem, 0, MEM_RELEASE);
 	FlushFileBuffers(bt->idx);
 	CloseHandle(bt->idx);
@@ -499,7 +500,7 @@ SYSTEM_INFO sysinfo[1];
 	else if( bits < BT_minbits )
 		bits = BT_minbits;
 
-	if ( bt_lockpage(bt, ALLOC_page, lockmode) )
+	if( bt_lockpage(bt, ALLOC_page, lockmode) )
 		return bt_close (bt), NULL;
 
 #ifdef unix
@@ -570,7 +571,7 @@ SYSTEM_INFO sysinfo[1];
 	bt->zero = (BtPage)(bt->mem + 5 * bt->page_size);
 
 	if( size || *amt ) {
-		if ( bt_unlockpage(bt, ALLOC_page, lockmode) )
+		if( bt_unlockpage(bt, ALLOC_page, lockmode) )
 			return bt_close (bt), NULL;
 
 		return bt;
@@ -672,12 +673,12 @@ BTERR bt_update (BtDb *bt, BtPage page, uid page_no)
 off64_t off = page_no << bt->page_bits;
 
 #ifdef unix
-    if ( !bt->mapped_io )
-	 if ( pwrite(bt->idx, page, bt->page_size, off) != bt->page_size )
+    if( !bt->mapped_io )
+	 if( pwrite(bt->idx, page, bt->page_size, off) != bt->page_size )
 		 return bt->err = BTERR_wrt;
 #else
 uint amt[1];
-	if ( !bt->mapped_io )
+	if( !bt->mapped_io )
 	{
 		SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
 		if( !WriteFile (bt->idx, (char *)page, bt->page_size, amt, NULL) )
@@ -686,7 +687,7 @@ uint amt[1];
 		if( *amt < bt->page_size )
 			return GetLastError(), bt->err = BTERR_wrt;
 	} 
-	else if ( bt->mode == BT_fl ) {
+	else if( bt->mode == BT_fl ) {
 			FlushViewOfFile(page, bt->page_size);
 			FlushFileBuffers(bt->idx);
 	}
@@ -874,7 +875,7 @@ int amt[1];
 		return bt->err;
 	}
 #ifdef unix
-	if ( pread(bt->idx, *page, bt->page_size, off) < bt->page_size )
+	if( pread(bt->idx, *page, bt->page_size, off) < bt->page_size )
 		return bt->err = BTERR_map;
 #else
 	SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
@@ -893,22 +894,12 @@ int amt[1];
 
 BTERR bt_freepage(BtDb *bt, uid page_no)
 {
-	//  obtain delete lock on deleted node
-
-	if( bt_lockpage(bt, page_no, BtLockDelete) )
-		return bt->err;
-
-	//  obtain write lock on deleted node
-
-	if( bt_lockpage(bt, page_no, BtLockWrite) )
-		return bt->err;
-
 	if( bt_mappage (bt, &bt->temp, page_no) )
 		return bt->err;
 
 	//	lock allocation page
 
-	if ( bt_lockpage(bt, ALLOC_page, BtLockWrite) )
+	if( bt_lockpage(bt, ALLOC_page, BtLockWrite) )
 		return bt->err;
 
 	if( bt_mappage (bt, &bt->alloc, ALLOC_page) )
@@ -917,6 +908,7 @@ BTERR bt_freepage(BtDb *bt, uid page_no)
 	//	store chain in second right
 	bt_putid(bt->temp->right, bt_getid(bt->alloc[1].right));
 	bt_putid(bt->alloc[1].right, page_no);
+	bt->temp->free = 1;
 
 	if( bt_update(bt, bt->alloc, ALLOC_page) )
 		return bt->err;
@@ -951,7 +943,7 @@ int reuse;
 
 	// lock page zero
 
-	if ( bt_lockpage(bt, ALLOC_page, BtLockWrite) )
+	if( bt_lockpage(bt, ALLOC_page, BtLockWrite) )
 		return 0;
 
 	if( bt_mappage (bt, &bt->alloc, ALLOC_page) )
@@ -980,23 +972,23 @@ int reuse;
 
 		// unlock page zero 
 
-		if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+		if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
 			return 0;
 
 		return new_page;
 	}
 
 #ifdef unix
-	if ( pwrite(bt->idx, page, bt->page_size, new_page << bt->page_bits) < bt->page_size )
+	if( pwrite(bt->idx, page, bt->page_size, new_page << bt->page_bits) < bt->page_size )
 		return bt->err = BTERR_wrt, 0;
 
 	// if writing first page of hash block, zero last page in the block
 
-	if ( !reuse && bt->hashmask > 0 && (new_page & bt->hashmask) == 0 )
+	if( !reuse && bt->hashmask > 0 && (new_page & bt->hashmask) == 0 )
 	{
 		// use temp buffer to write zeros
 		memset(bt->zero, 0, bt->page_size);
-		if ( pwrite(bt->idx,bt->zero, bt->page_size, (new_page | bt->hashmask) << bt->page_bits) < bt->page_size )
+		if( pwrite(bt->idx,bt->zero, bt->page_size, (new_page | bt->hashmask) << bt->page_bits) < bt->page_size )
 			return bt->err = BTERR_wrt, 0;
 	}
 #else
@@ -1011,7 +1003,7 @@ int reuse;
 
 	// unlock page zero 
 
-	if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+	if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
 		return 0;
 
 	return new_page;
@@ -1024,16 +1016,6 @@ int bt_findslot (BtDb *bt, unsigned char *key, uint len)
 uint diff, higher = bt->page->cnt, low = 1, slot;
 uint good = 0;
 
-	//	if page is being deleted, send to right
-
-	if( !bt->page->cnt )
-		return 0;
-
-	//	if page is an empty fence holder
-
-	if( !bt->page->act )
-		return bt->page->cnt;
-
 	//	make stopper key an infinite fence value
 
 	if( bt_getid (bt->page->right) )
@@ -1041,7 +1023,7 @@ uint good = 0;
 	else
 		good++;
 
-	//	low is the next candidate, higher is already
+	//	low is the lowest candidate, higher is already
 	//	tested as .ge. the given key, loop ends when they meet
 
 	while( diff = higher - low ) {
@@ -1068,8 +1050,6 @@ uint mode, prevmode;
 
   //  start at root of btree and drill down
 
-  bt->posted = 1;
-
   do {
 	// determine lock mode of drill level
 	mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead; 
@@ -1103,22 +1083,26 @@ uint mode, prevmode;
 	// re-read and re-lock root after determining actual level of root
 
 	if( bt->page->lvl != drill) {
-		if ( bt->page_no != ROOT_page )
+		if( bt->page_no != ROOT_page )
 			return bt->err = BTERR_struct, 0;
 			
 		drill = bt->page->lvl;
 
-		if( lock == BtLockWrite && drill == lvl )
+		if( lock != BtLockRead && drill == lvl )
 		  if( bt_unlockpage(bt, page_no, mode) )
 			return 0;
 		  else
 			continue;
 	}
 
+	prevpage = bt->page_no;
+	prevmode = mode;
+
 	//  find key on page at this level
 	//  and descend to requested level
 
-	if( slot = bt_findslot (bt, key, len) ) {
+	if( !bt->page->kill )
+	 if( slot = bt_findslot (bt, key, len) ) {
 	  if( drill == lvl )
 		return slot;
 
@@ -1126,27 +1110,18 @@ uint mode, prevmode;
 		if( slot++ < bt->page->cnt )
 			continue;
 		else
-			return bt->err = BTERR_struct, 0;
+			goto slideright;
 
 	  page_no = bt_getid(slotptr(bt->page, slot)->id);
-	  bt->fence = slot == bt->page->cnt;
-	  bt->posted = 1;
 	  drill--;
-	}
+	  continue;
+	 }
 
 	//  or slide right into next page
-	//  (slide left from deleted page)
-
-	else {
-		page_no = bt_getid(bt->page->right);
-		bt->posted = 0;
-	}
 
-	//  continue down / right using overlapping locks
-	//  to protect pages being killed or split.
+slideright:
+	page_no = bt_getid(bt->page->right);
 
-	prevpage = bt->page_no;
-	prevmode = mode;
   } while( page_no );
 
   // return error on end of right chain
@@ -1155,13 +1130,95 @@ uint mode, prevmode;
   return 0;	// return error
 }
 
+//	a fence key was deleted from a page
+//	push new fence value upwards
+
+BTERR bt_fixfence (BtDb *bt, uid page_no, uint lvl)
+{
+unsigned char leftkey[256], rightkey[256];
+BtKey ptr;
+
+	// remove deleted key, the old fence value
+
+	ptr = keyptr(bt->page, bt->page->cnt);
+	memcpy(rightkey, ptr, ptr->len + 1);
+
+	memset (slotptr(bt->page, bt->page->cnt--), 0, sizeof(BtSlot));
+	bt->page->dirty = 1;
+
+	ptr = keyptr(bt->page, bt->page->cnt);
+	memcpy(leftkey, ptr, ptr->len + 1);
+
+	if( bt_update (bt, bt->page, page_no) )
+		return bt->err;
+
+	if( bt_lockpage (bt, page_no, BtLockParent) )
+		return bt->err;
+
+	if( bt_unlockpage (bt, page_no, BtLockWrite) )
+		return bt->err;
+
+	//  insert new (now smaller) fence key
+
+	if( bt_insertkey (bt, leftkey+1, *leftkey, lvl + 1, page_no, time(NULL)) )
+		return bt->err;
+
+	//  remove old (larger) fence key
+
+	if( bt_deletekey (bt, rightkey+1, *rightkey, lvl + 1) )
+		return bt->err;
+
+	return bt_unlockpage (bt, page_no, BtLockParent);
+}
+
+//	root has a single child
+//	collapse a level from the btree
+//	call with root locked in bt->page
+
+BTERR bt_collapseroot (BtDb *bt, BtPage root)
+{
+uid child;
+uint idx;
+
+	// find the child entry
+	//	and promote to new root
+
+  do {
+	for( idx = 0; idx++ < root->cnt; )
+	  if( !slotptr(root, idx)->dead )
+		break;
+
+	child = bt_getid (slotptr(root, idx)->id);
+
+	if( bt_lockpage (bt, child, BtLockDelete) )
+		return bt->err;
+
+	if( bt_lockpage (bt, child, BtLockWrite) )
+		return bt->err;
+
+	if( bt_mappage (bt, &bt->temp, child) )
+		return bt->err;
+
+	memcpy (root, bt->temp, bt->page_size);
+
+	if( bt_update (bt, root, ROOT_page) )
+		return bt->err;
+
+	if( bt_freepage (bt, child) )
+		return bt->err;
+
+  } while( root->lvl > 1 && root->act == 1 );
+
+  return bt_unlockpage (bt, ROOT_page, BtLockWrite);
+}
+
 //  find and delete key on page by marking delete flag bit
 //  when page becomes empty, delete it
 
 BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
 {
 unsigned char lowerkey[256], higherkey[256];
-uint slot, tod, dirty = 0;
+uint slot, dirty = 0, idx, fence, found;
 uid page_no, right;
 BtKey ptr;
 
@@ -1170,32 +1227,56 @@ BtKey ptr;
 	else
 		return bt->err;
 
+	// are we deleting a fence slot?
+
+	fence = slot == bt->page->cnt;
+
 	// if key is found delete it, otherwise ignore request
 
-	if( !keycmp (ptr, key, len) )
-		if( slotptr(bt->page, slot)->dead == 0 ) {
- 			dirty = slotptr(bt->page,slot)->dead = 1;
-			if( slot < bt->page->cnt )
- 				bt->page->dirty = 1;
- 			bt->page->act--;
-		}
+	if( found = !keycmp (ptr, key, len) )
+	  if( found = slotptr(bt->page, slot)->dead == 0 ) {
+ 		dirty = slotptr(bt->page,slot)->dead = 1;
+ 		bt->page->dirty = 1;
+ 		bt->page->act--;
 
-	// return if page is not empty, or
-	//	if non-leaf level or fence key
+		// collapse empty slots
+
+		while( idx = bt->page->cnt - 1 )
+		  if( slotptr(bt->page, idx)->dead ) {
+			*slotptr(bt->page, idx) = *slotptr(bt->page, idx + 1);
+			memset (slotptr(bt->page, bt->page->cnt--), 0, sizeof(BtSlot));
+		  } else
+			break;
+	  }
 
 	right = bt_getid(bt->page->right);
 	page_no = bt->page_no;
 
-	if( lvl || bt->page->act || bt->fence )
-	  if ( dirty && bt_update(bt, bt->page, page_no) )
+	//	did we delete a fence key in an upper level?
+
+	if( dirty && lvl && bt->page->act && fence )
+	  if( bt_fixfence (bt, page_no, lvl) )
 		return bt->err;
 	  else
-		return bt_unlockpage(bt, page_no, BtLockWrite);
+		return bt->found = found, 0;
 
-	// obtain Parent lock over write lock
+	//	is this a collapsed root?
 
-	if( bt_lockpage(bt, page_no, BtLockParent) )
+	if( lvl > 1 && page_no == ROOT_page && bt->page->act == 1 )
+	  if( bt_collapseroot (bt, bt->page) )
+		return bt->err;
+	  else
+		return bt->found = found, 0;
+
+	// return if page is not empty
+
+	if( bt->page->act ) {
+	  if( dirty && bt_update(bt, bt->page, page_no) )
+		return bt->err;
+	  if( bt_unlockpage(bt, page_no, BtLockWrite) )
 		return bt->err;
+	  return bt->found = found, 0;
+	}
 
 	// cache copy of fence key
 	//	in order to find parent
@@ -1203,14 +1284,17 @@ BtKey ptr;
 	ptr = keyptr(bt->page, bt->page->cnt);
 	memcpy(lowerkey, ptr, ptr->len + 1);
 
-	// lock and map right page
+	// obtain lock on right page
 
-	if ( bt_lockpage(bt, right, BtLockWrite) )
+	if( bt_lockpage(bt, right, BtLockWrite) )
 		return bt->err;
 
 	if( bt_mappage (bt, &bt->temp, right) )
 		return bt->err;
 
+	if( bt->temp->kill )
+		return bt->err = BTERR_struct;
+
 	// pull contents of next page into current empty page 
 
 	memcpy (bt->page, bt->temp, bt->page_size);
@@ -1224,7 +1308,7 @@ BtKey ptr;
 	//	until we can post updates at higher level.
 
 	bt_putid(bt->temp->right, page_no);
-	bt->temp->cnt = 0;
+	bt->temp->kill = 1;
 
 	if( bt_update(bt, bt->page, page_no) )
 		return bt->err;
@@ -1232,36 +1316,46 @@ BtKey ptr;
 	if( bt_update(bt, bt->temp, right) )
 		return bt->err;
 
-	if( bt_unlockpage(bt, right, BtLockWrite) )
+	if( bt_lockpage(bt, page_no, BtLockParent) )
 		return bt->err;
 
 	if( bt_unlockpage(bt, page_no, BtLockWrite) )
 		return bt->err;
 
-	//  delete old lower key to consolidated node
+	if( bt_lockpage(bt, right, BtLockParent) )
+		return bt->err;
 
-	if( bt_deletekey (bt, lowerkey + 1, *lowerkey, lvl + 1) )
+	if( bt_unlockpage(bt, right, BtLockWrite) )
 		return bt->err;
 
 	//  redirect higher key directly to consolidated node
 
-	tod = (uint)time(NULL);
+	if( bt_insertkey (bt, higherkey+1, *higherkey, lvl+1, page_no, time(NULL)) )
+		return bt->err;
+
+	//  delete old lower key to consolidated node
 
-	if( bt_insertkey (bt, higherkey+1, *higherkey, lvl + 1, page_no, tod) )
+	if( bt_deletekey (bt, lowerkey + 1, *lowerkey, lvl + 1) )
 		return bt->err;
 
-	//	obtain write lock and
+	//  obtain write & delete lock on deleted node
 	//	add right block to free chain
 
+	if( bt_lockpage(bt, right, BtLockDelete) )
+		return bt->err;
+
+	if( bt_lockpage(bt, right, BtLockWrite) )
+		return bt->err;
+
 	if( bt_freepage (bt, right) )
 		return bt->err;
 
-	// 	remove ParentModify lock
+	// 	remove ParentModify locks
 
-	if( bt_unlockpage(bt, page_no, BtLockParent) )
+	if( bt_unlockpage(bt, right, BtLockParent) )
 		return bt->err;
-	
-	return 0;
+
+	return bt_unlockpage(bt, page_no, BtLockParent);
 }
 
 //	find key in leaf level and return row-id
@@ -1285,7 +1379,7 @@ uid id;
 	else
 		id = 0;
 
-	if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+	if( bt_unlockpage(bt, bt->page_no, BtLockRead) )
 		return 0;
 
 	return id;
@@ -1352,16 +1446,16 @@ int ret;
 
 // split the root and raise the height of the btree
 
-BTERR bt_splitroot(BtDb *bt,  unsigned char *newkey, unsigned char *oldkey, uid page_no2)
+BTERR bt_splitroot(BtDb *bt, unsigned char *leftkey, uid page_no2)
 {
 uint nxt = bt->page_size;
 BtPage root = bt->page;
-uid new_page;
+uid right;
 
 	//  Obtain an empty page to use, and copy the current
 	//  root contents into it
 
-	if( !(new_page = bt_newpage(bt, root)) )
+	if( !(right = bt_newpage(bt, root)) )
 		return bt->err;
 
 	// preserve the page info at the bottom
@@ -1371,16 +1465,18 @@ uid new_page;
 
 	// insert first key on newroot page
 
-	nxt -= *newkey + 1;
-	memcpy ((unsigned char *)root + nxt, newkey, *newkey + 1);
-	bt_putid(slotptr(root, 1)->id, new_page);
+	nxt -= *leftkey + 1;
+	memcpy ((unsigned char *)root + nxt, leftkey, *leftkey + 1);
+	bt_putid(slotptr(root, 1)->id, right);
 	slotptr(root, 1)->off = nxt;
 	
 	// insert second key on newroot page
 	// and increase the root height
 
-	nxt -= *oldkey + 1;
-	memcpy ((unsigned char *)root + nxt, oldkey, *oldkey + 1);
+	nxt -= 3;
+	((unsigned char *)root)[nxt] = 2;
+	((unsigned char *)root)[nxt+1] = 0xff;
+	((unsigned char *)root)[nxt+2] = 0xff;
 	bt_putid(slotptr(root, 2)->id, page_no2);
 	slotptr(root, 2)->off = nxt;
 
@@ -1404,21 +1500,17 @@ uid new_page;
 BTERR bt_splitpage (BtDb *bt)
 {
 uint cnt = 0, idx = 0, max, nxt = bt->page_size;
-unsigned char oldkey[256], lowerkey[256];
+unsigned char fencekey[256], rightkey[256];
 uid page_no = bt->page_no, right;
 BtPage page = bt->page;
 uint lvl = page->lvl;
-uid new_page;
 BtKey key;
-uint tod;
 
 	//  split higher half of keys to bt->frame
 	//	the last key (fence key) might be dead
 
-	tod = (uint)time(NULL);
-
 	memset (bt->frame, 0, bt->page_size);
-	max = (int)page->cnt;
+	max = page->cnt;
 	cnt = max / 2;
 	idx = 0;
 
@@ -1433,9 +1525,9 @@ uint tod;
 		slotptr(bt->frame, idx)->off = nxt;
 	}
 
-	// remember existing fence key for new page to the right
+	//	remember fence key for new right page
 
-	memcpy (oldkey, key, key->len + 1);
+	memcpy (rightkey, key, key->len + 1);
 
 	bt->frame->bits = bt->page_bits;
 	bt->frame->min = nxt;
@@ -1444,14 +1536,12 @@ uint tod;
 
 	// link right node
 
-	if( page_no > ROOT_page ) {
-		right = bt_getid (page->right);
-		bt_putid(bt->frame->right, right);
-	}
+	if( page_no > ROOT_page )
+		memcpy (bt->frame->right, page->right, BtId);
 
 	//	get new free page and write frame to it.
 
-	if( !(new_page = bt_newpage(bt, bt->frame)) )
+	if( !(right = bt_newpage(bt, bt->frame)) )
 		return bt->err;
 
 	//	update lower keys to continue in old page
@@ -1459,6 +1549,7 @@ uint tod;
 	memcpy (bt->frame, page, bt->page_size);
 	memset (page+1, 0, bt->page_size - sizeof(*page));
 	nxt = bt->page_size;
+	page->dirty = 0;
 	page->act = 0;
 	cnt = 0;
 	idx = 0;
@@ -1476,56 +1567,49 @@ uint tod;
 		page->act++;
 	}
 
-	// remember fence key for old page
+	// remember fence key for smaller page
 
-	memcpy(lowerkey, key, key->len + 1);
-	bt_putid(page->right, new_page);
+	memcpy (fencekey, key, key->len + 1);
+
+	bt_putid(page->right, right);
 	page->min = nxt;
 	page->cnt = idx;
 
 	// if current page is the root page, split it
 
 	if( page_no == ROOT_page )
-		return bt_splitroot (bt, lowerkey, oldkey, new_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;
 
-	// obtain Parent/Write locks
-	// for left and right node pages
+	// update left (containing) node
 
-	if( bt_lockpage (bt, new_page, BtLockParent) )
+	if( bt_update(bt, page, page_no) )
 		return bt->err;
 
 	if( bt_lockpage (bt, page_no, BtLockParent) )
 		return bt->err;
 
-	//  release wr lock on left page
-
 	if( bt_unlockpage (bt, page_no, BtLockWrite) )
 		return bt->err;
 
 	// insert new fence for reformulated left block
 
-	if( bt_insertkey (bt, lowerkey+1, *lowerkey, lvl + 1, page_no, tod) )
+	if( bt_insertkey (bt, fencekey+1, *fencekey, lvl+1, page_no, time(NULL)) )
 		return bt->err;
 
-	// fix old fence for newly allocated right block page
+	//	switch fence for right block of larger keys to new right page
 
-	if( bt_insertkey (bt, oldkey+1, *oldkey, lvl + 1, new_page, tod) )
-		return bt->err;
-
-	// release Parent & Write locks
-
-	if( bt_unlockpage (bt, new_page, BtLockParent) )
+	if( bt_insertkey (bt, rightkey+1, *rightkey, lvl+1, right, time(NULL)) )
 		return bt->err;
 
 	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.
@@ -1543,7 +1627,7 @@ BtKey ptr;
 		ptr = keyptr(bt->page, slot);
 	else
 	{
-		if ( !bt->err )
+		if( !bt->err )
 			bt->err = BTERR_ovflw;
 		return bt->err;
 	}
@@ -1553,12 +1637,14 @@ BtKey ptr;
 	page = bt->page;
 
 	if( !keycmp (ptr, key, len) ) {
-		slotptr(page, slot)->dead = 0;
-		slotptr(page, slot)->tod = tod;
-		bt_putid(slotptr(page,slot)->id, id);
-		if ( bt_update(bt, bt->page, bt->page_no) )
-			return bt->err;
-		return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+	  if( slotptr(page, slot)->dead )
+		page->act++;
+	  slotptr(page, slot)->dead = 0;
+	  slotptr(page, slot)->tod = tod;
+	  bt_putid(slotptr(page,slot)->id, id);
+	  if( bt_update(bt, bt->page, bt->page_no) )
+		return bt->err;
+	  return bt_unlockpage(bt, bt->page_no, BtLockWrite);
 	}
 
 	// check if page has enough space
@@ -1596,7 +1682,7 @@ BtKey ptr;
   slotptr(page, slot)->tod = tod;
   slotptr(page, slot)->dead = 0;
 
-  if ( bt_update(bt, bt->page, bt->page_no) )
+  if( bt_update(bt, bt->page, bt->page_no) )
 	  return bt->err;
 
   return bt_unlockpage(bt, bt->page_no, BtLockWrite);
@@ -1609,11 +1695,16 @@ uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
 uint slot;
 
 	// cache page for retrieval
+
 	if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
-		memcpy (bt->cursor, bt->page, bt->page_size);
+	  memcpy (bt->cursor, bt->page, bt->page_size);
+	else
+	  return 0;
+
 	bt->cursor_page = bt->page_no;
-	if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
-		return 0;
+
+	if( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+	  return 0;
 
 	return slot;
 }
@@ -1627,6 +1718,7 @@ off64_t right;
 
   do {
 	right = bt_getid(bt->cursor->right);
+
 	while( slot++ < bt->cursor->cnt )
 	  if( slotptr(bt->cursor,slot)->dead )
 		continue;
@@ -1640,17 +1732,19 @@ off64_t right;
 
 	bt->cursor_page = right;
 
-    if( bt_lockpage(bt, right,BtLockRead) )
+    if( bt_lockpage(bt, right, BtLockRead) )
 		return 0;
 
 	if( bt_mappage (bt, &bt->page, right) )
-		break;
+		return 0;
 
 	memcpy (bt->cursor, bt->page, bt->page_size);
-	if ( bt_unlockpage(bt, right, BtLockRead) )
+
+	if( bt_unlockpage(bt, right, BtLockRead) )
 		return 0;
 
 	slot = 0;
+
   } while( 1 );
 
   return bt->err = 0;
@@ -1673,6 +1767,68 @@ uint bt_tod(BtDb *bt, uint slot)
 
 
 #ifdef STANDALONE
+
+#ifndef unix
+double getCpuTime(int type)
+{
+FILETIME crtime[1];
+FILETIME xittime[1];
+FILETIME systime[1];
+FILETIME usrtime[1];
+SYSTEMTIME timeconv[1];
+double ans = 0;
+
+	memset (timeconv, 0, sizeof(SYSTEMTIME));
+
+	switch( type ) {
+	case 0:
+		GetSystemTimeAsFileTime (xittime);
+		FileTimeToSystemTime (xittime, timeconv);
+		ans = (double)timeconv->wDayOfWeek * 3600 * 24;
+		break;
+	case 1:
+		GetProcessTimes (GetCurrentProcess(), crtime, xittime, systime, usrtime);
+		FileTimeToSystemTime (usrtime, timeconv);
+		break;
+	case 2:
+		GetProcessTimes (GetCurrentProcess(), crtime, xittime, systime, usrtime);
+		FileTimeToSystemTime (systime, timeconv);
+		break;
+	}
+
+	ans += (double)timeconv->wHour * 3600;
+	ans += (double)timeconv->wMinute * 60;
+	ans += (double)timeconv->wSecond;
+	ans += (double)timeconv->wMilliseconds / 1000;
+	return ans;
+}
+#else
+#include <time.h>
+#include <sys/resource.h>
+
+double getCpuTime(int type)
+{
+struct rusage used[1];
+struct timeval tv[1];
+
+	switch( type ) {
+	case 0:
+		gettimeofday(tv, NULL);
+		return (double)tv->tv_sec + (double)tv->tv_usec / 1000000;
+
+	case 1:
+		getrusage(RUSAGE_SELF, used);
+		return (double)used->ru_utime.tv_sec + (double)used->ru_utime.tv_usec / 1000000;
+
+	case 2:
+		getrusage(RUSAGE_SELF, used);
+		return (double)used->ru_stime.tv_sec + (double)used->ru_stime.tv_usec / 1000000;
+	}
+
+	return 0;
+}
+#endif
+
 //  standalone program to index file of keys
 //  then list them onto std-out
 
@@ -1681,12 +1837,14 @@ int main (int argc, char **argv)
 uint slot, line = 0, off = 0, found = 0;
 int dead, ch, cnt = 0, bits = 12;
 unsigned char key[256];
-clock_t done, start;
+double done, start;
 uint pgblk = 0;
+float elapsed;
 time_t tod[1];
 uint scan = 0;
 uint len = 0;
 uint map = 0;
+uid page_no;
 BtKey ptr;
 BtDb *bt;
 FILE *in;
@@ -1699,7 +1857,7 @@ FILE *in;
 		exit(0);
 	}
 
-	start = clock();
+	start = getCpuTime(0);
 	time(tod);
 
 	if( argc > 4 )
@@ -1747,7 +1905,7 @@ FILE *in;
 			}
 			else if( len < 245 )
 				key[len++] = ch;
-		fprintf(stderr, "finished adding keys, %d \n", line);
+		fprintf(stderr, "finished adding keys for %s, %d \n", argv[2], line);
 		break;
 
 	case 'd':
@@ -1765,7 +1923,7 @@ FILE *in;
 			}
 			else if( len < 245 )
 				key[len++] = ch;
-		fprintf(stderr, "finished deleting keys, %d \n", line);
+		fprintf(stderr, "finished deleting keys for %s, %d \n", argv[2], line);
 		break;
 
 	case 'f':
@@ -1785,36 +1943,69 @@ FILE *in;
 			}
 			else if( len < 245 )
 				key[len++] = ch;
-		fprintf(stderr, "finished search of %d keys, found %d\n", line, found);
+		fprintf(stderr, "finished search of %d keys for %s, found %d\n", line, argv[2], found);
 		break;
 
 	case 's':
-		scan++;
-		break;
+		cnt = len = key[0] = 0;
 
-	}
+		if( slot = bt_startkey (bt, key, len) )
+		  slot--;
+		else
+		  fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
 
-	done = clock();
-	fprintf(stderr, " Time to complete: %.2f seconds\n", (float)(done - start) / CLOCKS_PER_SEC);
+		while( slot = bt_nextkey (bt, slot) ) {
+			ptr = bt_key(bt, slot);
+			fwrite (ptr->key, ptr->len, 1, stdout);
+			fputc ('\n', stdout);
+			cnt++;
+	  	}
 
-	dead = cnt = 0;
-	len = key[0] = 0;
+	  fprintf(stderr, " Total keys read %d\n", cnt - 1);
+	  break;
 
-	fprintf(stderr, "started reading\n");
+	case 'c':
+	  fprintf(stderr, "started counting\n");
+	  cnt = 0;
 
-	if( slot = bt_startkey (bt, key, len) )
-	  slot--;
-	else
-	  fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+	  page_no = LEAF_page;
+	  cnt = 0;
 
-	while( slot = bt_nextkey (bt, slot) )
-	  if( cnt++, scan ) {
-			ptr = bt_key(bt, slot);
-			fwrite (ptr->key, ptr->len, 1, stdout);
-			fputc ('\n', stdout);
+	  while( 1 ) {
+	  uid off = page_no << bt->page_bits;
+#ifdef unix
+	  	if( !pread (bt->idx, bt->frame, bt->page_size, off) )
+			break;
+#else
+		DWORD amt[1];
+
+	  	SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
+
+	  	if( !ReadFile(bt->idx, bt->frame, bt->page_size, amt, NULL))
+			break;
+
+	  	if( *amt <  bt->page_size )
+			fprintf (stderr, "unable to read page %.8x", page_no);
+#endif
+		if( !bt->frame->free && !bt->frame->lvl )
+			cnt += bt->frame->act;
+
+		page_no++;
 	  }
+		
+	  cnt--;	// remove stopper key
+	  fprintf(stderr, " Total keys read %d\n", cnt);
+	  break;
+	}
+
+	done = getCpuTime(0);
+	elapsed = (float)(done - start);
+	fprintf(stderr, " real %dm%.3fs\n", (int)(elapsed/60), elapsed - (int)(elapsed/60)*60);
+	elapsed = getCpuTime(1);
+	fprintf(stderr, " user %dm%.3fs\n", (int)(elapsed/60), elapsed - (int)(elapsed/60)*60);
+	elapsed = getCpuTime(2);
+	fprintf(stderr, " sys  %dm%.3fs\n", (int)(elapsed/60), elapsed - (int)(elapsed/60)*60);
 
-	fprintf(stderr, " Total keys read %d\n", cnt);
 	return 0;
 }