X-Git-Url: https://pd.if.org/git/?p=btree;a=blobdiff_plain;f=threads2i.c;h=f1d0269b89776928b209bef823aa65c40c4f91ae;hp=73d7541c013d260c76edc2c917e4b0a4dde15fff;hb=HEAD;hpb=b1c2f6235b3d7babfa46849a36b9a370a907b640

diff --git a/threads2i.c b/threads2i.c
index 73d7541..f1d0269 100644
--- a/threads2i.c
+++ b/threads2i.c
@@ -1,5 +1,6 @@
 // btree version threads2i sched_yield version
-// 30 JAN 2014
+//	with reworked bt_deletekey code
+// 17 FEB 2014
 
 // author: karl malbrain, malbrain@cal.berkeley.edu
 
@@ -49,6 +50,7 @@ REDISTRIBUTION OF THIS SOFTWARE.
 
 #include <memory.h>
 #include <string.h>
+#include <stddef.h>
 
 typedef unsigned long long	uid;
 
@@ -85,24 +87,17 @@ typedef enum{
 	BtLockParent
 } BtLock;
 
-//	mode & definition for latch implementation
-
-enum {
-	Mutex = 1,
-	Write = 2,
-	Pending = 4,
-	Share = 8
-} LockMode;
+//	definition for latch implementation
 
 // exclusive is set for write access
 // share is count of read accessors
 // grant write lock when share == 0
 
-typedef struct {
-	volatile ushort mutex:1;
-	volatile ushort exclusive:1;
-	volatile ushort pending:1;
-	volatile ushort share:13;
+volatile typedef struct {
+	unsigned char mutex[1];
+	unsigned char exclusive:1;
+	unsigned char pending:1;
+	ushort share;
 } BtSpinLatch;
 
 //  hash table entries
@@ -117,7 +112,7 @@ typedef struct {
 typedef struct {
 	BtSpinLatch readwr[1];		// read/write page lock
 	BtSpinLatch access[1];		// Access Intent/Page delete
-	BtSpinLatch parent[1];		// adoption of foster children
+	BtSpinLatch parent[1];		// Posting of fence key in parent
 	BtSpinLatch busy[1];		// slot is being moved between chains
 	volatile ushort next;		// next entry in hash table chain
 	volatile ushort prev;		// prev entry in hash table chain
@@ -149,7 +144,7 @@ typedef struct {
 } BtSlot;
 
 //	The key structure occupies space at the upper end of
-//	each page.  It's a length byte followed by the value
+//	each page.  It's a length byte followed by the key
 //	bytes.
 
 typedef struct {
@@ -161,12 +156,14 @@ typedef struct {
 //	It is immediately followed
 //	by the BtSlot array of keys.
 
-typedef struct Page {
+typedef struct BtPage_ {
 	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 chain
+	unsigned char lvl:6;		// level of page
+	unsigned char kill:1;		// page is being deleted
 	unsigned char dirty:1;		// page has deleted keys
 	unsigned char right[BtId];	// page number to right
 } *BtPage;
@@ -174,7 +171,6 @@ typedef struct Page {
 //	The memory mapping pool table buffer manager entry
 
 typedef struct {
-	unsigned long long int lru;	// number of times accessed
 	uid  basepage;				// mapped base page number
 	char *map;					// mapped memory pointer
 	ushort slot;				// slot index in this array
@@ -186,10 +182,21 @@ typedef struct {
 #endif
 } BtPool;
 
+#define CLOCK_bit 0x8000		// bit in pool->pin
+
+//  The loadpage interface object
+
+typedef struct {
+	uid page_no;		// current page number
+	BtPage page;		// current page pointer
+	BtPool *pool;		// current page pool
+	BtLatchSet *latch;	// current page latch set
+} BtPageSet;
+
 //	structure for latch manager on ALLOC_page
 
 typedef struct {
-	struct Page alloc[2];		// next & free page_nos in right ptr
+	struct BtPage_ alloc[2];	// next & free page_nos in right ptr
 	BtSpinLatch lock[1];		// allocation area lite latch
 	ushort latchdeployed;		// highest number of latch entries deployed
 	ushort nlatchpage;			// number of latch pages at BT_latch
@@ -231,13 +238,8 @@ typedef struct {
 	BtPage cursor;		// cached frame for start/next (never mapped)
 	BtPage frame;		// spare frame for the page split (never mapped)
 	BtPage zero;		// page frame for zeroes at end of file
-	BtPage page;		// current page
-	uid page_no;		// current page number	
 	uid cursor_page;	// current cursor page number	
-	BtLatchSet *set;	// current page latch set
-	BtPool *pool;		// current page pool
 	unsigned char *mem;	// frame, cursor, page memory buffer
-	int parent;			// last loadpage was from a parent level
 	int found;			// last delete or insert was found
 	int err;			// last error
 } BtDb;
@@ -255,17 +257,12 @@ typedef enum {
 // B-Tree functions
 extern void bt_close (BtDb *bt);
 extern BtDb *bt_open (BtMgr *mgr);
-extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl);
-extern BTERR  bt_deletekey (BtDb *bt, unsigned char *key, uint len);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uint lvl, uid id, uint tod);
+extern BTERR  bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
 extern uid bt_findkey    (BtDb *bt, unsigned char *key, uint len);
 extern uint bt_startkey  (BtDb *bt, unsigned char *key, uint len);
 extern uint bt_nextkey   (BtDb *bt, uint slot);
 
-//	internal functions
-BTERR bt_splitpage (BtDb *bt, BtPage page, BtPool *pool, BtLatchSet *set, uid page_no);
-uint bt_cleanpage(BtDb *bt, BtPage page, uint amt, uint slot);
-BTERR bt_mergeleft (BtDb *bt, BtPage page, BtPool *pool, BtLatchSet *set, uid page_no, uint lvl);
-
 //	manager functions
 extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
 void bt_mgrclose (BtMgr *mgr);
@@ -295,7 +292,8 @@ extern uint bt_tod (BtDb *bt, uint slot);
 //  A key consists of a length byte, two bytes of
 //  index number (0 - 65534), and up to 253 bytes
 //  of key value.  Duplicate keys are discarded.
-//  Associated with each key is a 48 bit row-id.
+//  Associated with each key is a 48 bit row-id,
+//	or any other value desired.
 
 //  The b-tree root is always located at page 1.
 //	The first leaf page of level zero is always
@@ -310,8 +308,8 @@ extern uint bt_tod (BtDb *bt, uint slot);
 //	one with two keys.
 
 //	Deleted keys are marked with a dead bit until
-//	page cleanup The fence key for a node is always
-//	present, even after deletion and cleanup.
+//	page cleanup. The fence key for a node is
+//	always present
 
 //  Groups of pages called segments from the btree are optionally
 //  cached with a memory mapped pool. A hash table is used to keep
@@ -326,12 +324,13 @@ extern uint bt_tod (BtDb *bt, uint slot);
 //  Page 0 is dedicated to lock for new page extensions,
 //	and chains empty pages together for reuse.
 
-//	The ParentModification lock on a node is obtained to prevent resplitting
-//	or deleting a node before its fence is posted into its upper level.
+//	The ParentModification lock on a node is obtained to serialize posting
+//	or changing the fence key for a node.
 
 //	Empty pages are chained together through the ALLOC page and reused.
 
 //	Access macros to address slot and key values from the page
+//	Page slots use 1 based indexing.
 
 #define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
 #define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
@@ -367,29 +366,26 @@ ushort prev;
   do {
 	//	obtain latch mutex
 #ifdef unix
-	if( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex )
+	if( __sync_lock_test_and_set(latch->mutex, 1) )
 		continue;
 #else
-	if( prev = _InterlockedOr16((ushort *)latch, Mutex) & Mutex )
+	if( _InterlockedExchange8(latch->mutex, 1) )
 		continue;
 #endif
 	//  see if exclusive request is granted or pending
 
 	if( prev = !(latch->exclusive | latch->pending) )
-#ifdef unix
-		__sync_fetch_and_add((ushort *)latch, Share);
-#else
-		_InterlockedExchangeAdd16 ((ushort *)latch, Share);
-#endif
+		latch->share++;
 
 #ifdef unix
-	__sync_fetch_and_and ((ushort *)latch, ~Mutex);
+	*latch->mutex = 0;
 #else
-	_InterlockedAnd16((ushort *)latch, ~Mutex);
+	_InterlockedExchange8(latch->mutex, 0);
 #endif
 
 	if( prev )
 		return;
+
 #ifdef  unix
   } while( sched_yield(), 1 );
 #else
@@ -401,31 +397,27 @@ ushort prev;
 
 void bt_spinwritelock(BtSpinLatch *latch)
 {
+uint prev;
+
   do {
 #ifdef  unix
-	if( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
+	if( __sync_lock_test_and_set(latch->mutex, 1) )
 		continue;
 #else
-	if( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
+	if( _InterlockedExchange8(latch->mutex, 1) )
 		continue;
 #endif
-	if( !(latch->share | latch->exclusive) ) {
+	if( prev = !(latch->share | latch->exclusive) )
+		latch->exclusive = 1, latch->pending = 0;
+	else
+		latch->pending = 1;
 #ifdef unix
-		__sync_fetch_and_or((ushort *)latch, Write);
-		__sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
+	*latch->mutex = 0;
 #else
-		_InterlockedOr16((ushort *)latch, Write);
-		_InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
+	_InterlockedExchange8(latch->mutex, 0);
 #endif
+	if( prev )
 		return;
-	}
-
-#ifdef unix
-	__sync_fetch_and_and ((ushort *)latch, ~Mutex);
-#else
-	_InterlockedAnd16((ushort *)latch, ~Mutex);
-#endif
-
 #ifdef  unix
   } while( sched_yield(), 1 );
 #else
@@ -440,30 +432,26 @@ void bt_spinwritelock(BtSpinLatch *latch)
 
 int bt_spinwritetry(BtSpinLatch *latch)
 {
-ushort prev;
+uint prev;
 
 #ifdef unix
-	if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex )
+	if( __sync_lock_test_and_set(latch->mutex, 1) )
 		return 0;
 #else
-	if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex )
+	if( _InterlockedExchange8(latch->mutex, 1) )
 		return 0;
 #endif
 	//	take write access if all bits are clear
 
-	if( !prev )
-#ifdef unix
-		__sync_fetch_and_or ((ushort *)latch, Write);
-#else
-		_InterlockedOr16((ushort *)latch, Write);
-#endif
+	if( prev = !(latch->exclusive | latch->share) )
+		latch->exclusive = 1;
 
 #ifdef unix
-	__sync_fetch_and_and ((ushort *)latch, ~Mutex);
+	*latch->mutex = 0;
 #else
-	_InterlockedAnd16((ushort *)latch, ~Mutex);
+	_InterlockedExchange8(latch->mutex, 0);
 #endif
-	return !prev;
+	return prev;
 }
 
 //	clear write mode
@@ -471,9 +459,17 @@ ushort prev;
 void bt_spinreleasewrite(BtSpinLatch *latch)
 {
 #ifdef unix
-	__sync_fetch_and_and ((ushort *)latch, ~Write);
+	while( __sync_lock_test_and_set(latch->mutex, 1) )
+		sched_yield();
 #else
-	_InterlockedAnd16((ushort *)latch, ~Write);
+	while( _InterlockedExchange8(latch->mutex, 1) )
+		SwitchToThread();
+#endif
+	latch->exclusive = 0;
+#ifdef unix
+	*latch->mutex = 0;
+#else
+	_InterlockedExchange8(latch->mutex, 0);
 #endif
 }
 
@@ -482,9 +478,17 @@ void bt_spinreleasewrite(BtSpinLatch *latch)
 void bt_spinreleaseread(BtSpinLatch *latch)
 {
 #ifdef unix
-	__sync_fetch_and_add((ushort *)latch, -Share);
+	while( __sync_lock_test_and_set(latch->mutex, 1) )
+		sched_yield();
 #else
-	_InterlockedExchangeAdd16 ((ushort *)latch, -Share);
+	while( _InterlockedExchange8(latch->mutex, 1) )
+		SwitchToThread();
+#endif
+	latch->share--;
+#ifdef unix
+	*latch->mutex = 0;
+#else
+	_InterlockedExchange8(latch->mutex, 0);
 #endif
 }
 
@@ -693,14 +697,14 @@ uint slot;
 	close (mgr->idx);
 	free (mgr->pool);
 	free (mgr->hash);
-	free (mgr->latch);
+	free ((void *)mgr->latch);
 	free (mgr);
 #else
 	FlushFileBuffers(mgr->idx);
 	CloseHandle(mgr->idx);
 	GlobalFree (mgr->pool);
 	GlobalFree (mgr->hash);
-	GlobalFree (mgr->latch);
+	GlobalFree ((void *)mgr->latch);
 	GlobalFree (mgr);
 #endif
 }
@@ -710,10 +714,10 @@ uint slot;
 void bt_close (BtDb *bt)
 {
 #ifdef unix
-	if ( bt->mem )
+	if( bt->mem )
 		free (bt->mem);
 #else
-	if ( bt->mem)
+	if( bt->mem)
 		VirtualFree (bt->mem, 0, MEM_RELEASE);
 #endif
 	free (bt);
@@ -875,7 +879,7 @@ SYSTEM_INFO sysinfo[1];
 		slotptr(latchmgr->alloc, 1)->off = mgr->page_size - 3;
 		bt_putid(slotptr(latchmgr->alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0);		// next(lower) page number
 		key = keyptr(latchmgr->alloc, 1);
-		key->len = 2;			// create stopper key
+		key->len = 2;		// create stopper key
 		key->key[0] = 0xff;
 		key->key[1] = 0xff;
 		latchmgr->alloc->min = mgr->page_size - 3;
@@ -1024,7 +1028,7 @@ uint slot;
 
 	pool->hashprev = pool->hashnext = NULL;
 	pool->basepage = page_no & ~bt->mgr->poolmask;
-	pool->lru = 1;
+	pool->pin = CLOCK_bit + 1;
 
 	if( slot = bt->mgr->hash[idx] ) {
 		node = bt->mgr->pool + slot;
@@ -1035,32 +1039,6 @@ uint slot;
 	bt->mgr->hash[idx] = pool->slot;
 }
 
-//	find best segment to evict from buffer pool
-
-BtPool *bt_findlru (BtDb *bt, uint hashslot)
-{
-unsigned long long int target = ~0LL;
-BtPool *pool = NULL, *node;
-
-	if( !hashslot )
-		return NULL;
-
-	node = bt->mgr->pool + hashslot;
-
-	//  scan pool entries under hash table slot
-
-	do {
-	  if( node->pin )
-		continue;
-	  if( node->lru > target )
-		continue;
-	  target = node->lru;
-	  pool = node;
-	} while( node = node->hashnext );
-
-	return pool;
-}
-
 //  map new buffer pool segment to virtual memory
 
 BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no)
@@ -1116,42 +1094,25 @@ void bt_unpinpool (BtPool *pool)
 
 BtPool *bt_pinpool(BtDb *bt, uid page_no)
 {
+uint slot, hashidx, idx, victim;
 BtPool *pool, *node, *next;
-uint slot, idx, victim;
 
 	//	lock hash table chain
 
-	idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
-	bt_spinreadlock (&bt->mgr->latch[idx]);
+	hashidx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+	bt_spinwritelock (&bt->mgr->latch[hashidx]);
 
 	//	look up in hash table
 
-	if( pool = bt_findpool(bt, page_no, idx) ) {
+	if( pool = bt_findpool(bt, page_no, hashidx) ) {
 #ifdef unix
+		__sync_fetch_and_or(&pool->pin, CLOCK_bit);
 		__sync_fetch_and_add(&pool->pin, 1);
 #else
+		_InterlockedOr16 (&pool->pin, CLOCK_bit);
 		_InterlockedIncrement16 (&pool->pin);
 #endif
-		bt_spinreleaseread (&bt->mgr->latch[idx]);
-		pool->lru++;
-		return pool;
-	}
-
-	//	upgrade to write lock
-
-	bt_spinreleaseread (&bt->mgr->latch[idx]);
-	bt_spinwritelock (&bt->mgr->latch[idx]);
-
-	// try to find page in pool with write lock
-
-	if( pool = bt_findpool(bt, page_no, idx) ) {
-#ifdef unix
-		__sync_fetch_and_add(&pool->pin, 1);
-#else
-		_InterlockedIncrement16 (&pool->pin);
-#endif
-		bt_spinreleasewrite (&bt->mgr->latch[idx]);
-		pool->lru++;
+		bt_spinreleasewrite (&bt->mgr->latch[hashidx]);
 		return pool;
 	}
 
@@ -1171,13 +1132,8 @@ uint slot, idx, victim;
 		if( bt_mapsegment(bt, pool, page_no) )
 			return NULL;
 
-		bt_linkhash(bt, pool, page_no, idx);
-#ifdef unix
-		__sync_fetch_and_add(&pool->pin, 1);
-#else
-		_InterlockedIncrement16 (&pool->pin);
-#endif
-		bt_spinreleasewrite (&bt->mgr->latch[idx]);
+		bt_linkhash(bt, pool, page_no, hashidx);
+		bt_spinreleasewrite (&bt->mgr->latch[hashidx]);
 		return pool;
 	}
 
@@ -1196,20 +1152,30 @@ uint slot, idx, victim;
 #else
 		victim = _InterlockedIncrement (&bt->mgr->evicted) - 1;
 #endif
-		victim %= bt->mgr->hashsize;
+		victim %= bt->mgr->poolmax;
+		pool = bt->mgr->pool + victim;
+		idx = (uint)(pool->basepage >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+
+		if( !victim )
+			continue;
 
 		// try to get write lock
 		//	skip entry if not obtained
 
-		if( !bt_spinwritetry (&bt->mgr->latch[victim]) )
+		if( !bt_spinwritetry (&bt->mgr->latch[idx]) )
 			continue;
 
-		//  if pool entry is empty
-		//	or any pages are pinned
-		//	skip this entry
+		//	skip this entry if
+		//	page is pinned
+		//  or clock bit is set
 
-		if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
-			bt_spinreleasewrite (&bt->mgr->latch[victim]);
+		if( pool->pin ) {
+#ifdef unix
+			__sync_fetch_and_and(&pool->pin, ~CLOCK_bit);
+#else
+			_InterlockedAnd16 (&pool->pin, ~CLOCK_bit);
+#endif
+			bt_spinreleasewrite (&bt->mgr->latch[idx]);
 			continue;
 		}
 
@@ -1218,14 +1184,14 @@ uint slot, idx, victim;
 		if( node = pool->hashprev )
 			node->hashnext = pool->hashnext;
 		else if( node = pool->hashnext )
-			bt->mgr->hash[victim] = node->slot;
+			bt->mgr->hash[idx] = node->slot;
 		else
-			bt->mgr->hash[victim] = 0;
+			bt->mgr->hash[idx] = 0;
 
 		if( node = pool->hashnext )
 			node->hashprev = pool->hashprev;
 
-		bt_spinreleasewrite (&bt->mgr->latch[victim]);
+		bt_spinreleasewrite (&bt->mgr->latch[idx]);
 
 		//	remove old file mapping
 #ifdef unix
@@ -1243,13 +1209,8 @@ uint slot, idx, victim;
 		if( bt_mapsegment(bt, pool, page_no) )
 			return NULL;
 
-		bt_linkhash(bt, pool, page_no, idx);
-#ifdef unix
-		__sync_fetch_and_add(&pool->pin, 1);
-#else
-		_InterlockedIncrement16 (&pool->pin);
-#endif
-		bt_spinreleasewrite (&bt->mgr->latch[idx]);
+		bt_linkhash(bt, pool, page_no, hashidx);
+		bt_spinreleasewrite (&bt->mgr->latch[hashidx]);
 		return pool;
 	}
 }
@@ -1304,10 +1265,8 @@ void bt_unlockpage(BtLock mode, BtLatchSet *set)
 
 uid bt_newpage(BtDb *bt, BtPage page)
 {
-BtLatchSet *set;
-BtPool *pool;
+BtPageSet set[1];
 uid new_page;
-BtPage pmap;
 int reuse;
 
 	//	lock allocation page
@@ -1318,12 +1277,13 @@ int reuse;
 	// else allocate empty page
 
 	if( new_page = bt_getid(bt->mgr->latchmgr->alloc[1].right) ) {
-		if( pool = bt_pinpool (bt, new_page) )
-			pmap = bt_page (bt, pool, new_page);
+		if( set->pool = bt_pinpool (bt, new_page) )
+			set->page = bt_page (bt, set->pool, new_page);
 		else
 			return 0;
-		bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(pmap->right));
-		bt_unpinpool (pool);
+
+		bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(set->page->right));
+		bt_unpinpool (set->pool);
 		reuse = 1;
 	} else {
 		new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
@@ -1331,29 +1291,28 @@ int reuse;
 		reuse = 0;
 	}
 #ifdef unix
-	if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+	if( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
 		return bt->err = BTERR_wrt, 0;
 
 	// if writing first page of pool block, zero last page in the block
 
-	if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
+	if( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
 	{
 		// use zero buffer to write zeros
-		memset(bt->zero, 0, bt->mgr->page_size);
-		if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+		if( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
 			return bt->err = BTERR_wrt, 0;
 	}
 #else
 	//	bring new page into pool and copy page.
 	//	this will extend the file into the new pages.
 
-	if( pool = bt_pinpool (bt, new_page) )
-		pmap = bt_page (bt, pool, new_page);
+	if( set->pool = bt_pinpool (bt, new_page) )
+		set->page = bt_page (bt, set->pool, new_page);
 	else
 		return 0;
 
-	memcpy(pmap, page, bt->mgr->page_size);
-	bt_unpinpool (pool);
+	memcpy(set->page, page, bt->mgr->page_size);
+	bt_unpinpool (set->pool);
 #endif
 	// unlock allocation latch and return new page no
 
@@ -1363,29 +1322,27 @@ int reuse;
 
 //  find slot in page for given key at a given level
 
-int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+int bt_findslot (BtPageSet *set, unsigned char *key, uint len)
 {
-uint diff, higher = bt->page->cnt, low = 1, slot;
+uint diff, higher = set->page->cnt, low = 1, slot;
 uint good = 0;
 
-	//	if no right link
 	//	  make stopper key an infinite fence value
-	//	  by setting the good flag
 
-	if( bt_getid (bt->page->right) )
+	if( bt_getid (set->page->right) )
 		higher++;
 	else
 		good++;
 
-	//	low is the next candidate.
+	//	low is the lowest candidate.
 	//  loop ends when they meet
 
-	//  if good, higher is already
-	//	tested as .ge. the given key.
+	//  higher is already
+	//	tested as .ge. the passed key.
 
 	while( diff = higher - low ) {
 		slot = low + ( diff >> 1 );
-		if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+		if( keycmp (keyptr(set->page, slot), key, len) < 0 )
 			low = slot + 1;
 		else
 			higher = slot, good++;
@@ -1393,112 +1350,105 @@ uint good = 0;
 
 	//	return zero if key is on right link page
 
- 	return good ? higher : 0;
+	return good ? higher : 0;
 }
 
 //  find and load page at given level for given key
 //	leave page rd or wr locked as requested
 
-int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock)
+int bt_loadpage (BtDb *bt, BtPageSet *set, unsigned char *key, uint len, uint lvl, BtLock lock)
 {
 uid page_no = ROOT_page, prevpage = 0;
-BtLatchSet *set, *prevset;
 uint drill = 0xff, slot;
+BtLatchSet *prevlatch;
 uint mode, prevmode;
 BtPool *prevpool;
-int parent = 1;
 
   //  start at root of btree and drill down
 
-  bt->set = NULL;
-
   do {
 	// determine lock mode of drill level
-	mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead; 
+	mode = (drill == lvl) ? lock : BtLockRead; 
 
-	bt->set = bt_pinlatch (bt, page_no);
-	bt->page_no = page_no;
+	set->latch = bt_pinlatch (bt, page_no);
+	set->page_no = page_no;
 
 	// pin page contents
 
-	if( bt->pool = bt_pinpool (bt, page_no) )
-		bt->page = bt_page (bt, bt->pool, page_no);
+	if( set->pool = bt_pinpool (bt, page_no) )
+		set->page = bt_page (bt, set->pool, page_no);
 	else
 		return 0;
 
  	// obtain access lock using lock chaining with Access mode
 
 	if( page_no > ROOT_page )
-	  bt_lockpage(BtLockAccess, bt->set);
+	  bt_lockpage(BtLockAccess, set->latch);
 
 	//	release & unpin parent page
 
 	if( prevpage ) {
-	  bt_unlockpage(prevmode, prevset);
-	  bt_unpinlatch (prevset);
+	  bt_unlockpage(prevmode, prevlatch);
+	  bt_unpinlatch (prevlatch);
 	  bt_unpinpool (prevpool);
 	  prevpage = 0;
 	}
 
  	// obtain read lock using lock chaining
 
-	bt_lockpage(mode, bt->set);
+	bt_lockpage(mode, set->latch);
+
+	if( set->page->free )
+		return bt->err = BTERR_struct, 0;
 
 	if( page_no > ROOT_page )
-	  bt_unlockpage(BtLockAccess, bt->set);
+	  bt_unlockpage(BtLockAccess, set->latch);
 
 	// re-read and re-lock root after determining actual level of root
 
-	if( bt->page->lvl != drill) {
-		if ( bt->page_no != ROOT_page )
+	if( set->page->lvl != drill) {
+		if( set->page_no != ROOT_page )
 			return bt->err = BTERR_struct, 0;
 			
-		drill = bt->page->lvl;
+		drill = set->page->lvl;
 
-		if( lock == BtLockWrite && drill == lvl ) {
-		  bt_unlockpage(mode, bt->set);
-		  bt_unpinlatch (bt->set);
-		  bt_unpinpool (bt->pool);
+		if( lock != BtLockRead && drill == lvl ) {
+		  bt_unlockpage(mode, set->latch);
+		  bt_unpinlatch (set->latch);
+		  bt_unpinpool (set->pool);
 		  continue;
 		}
 	}
 
+	prevpage = set->page_no;
+	prevlatch = set->latch;
+	prevpool = set->pool;
+	prevmode = mode;
+
 	//  find key on page at this level
 	//  and descend to requested level
 
-	if( slot = bt_findslot (bt, key, len) ) {
+	if( !set->page->kill )
+	 if( slot = bt_findslot (set, key, len) ) {
 	  if( drill == lvl )
-		return bt->parent = parent, slot;
+		return slot;
 
-	  while( slotptr(bt->page, slot)->dead )
-		if( slot++ < bt->page->cnt )
+	  while( slotptr(set->page, slot)->dead )
+		if( slot++ < set->page->cnt )
 			continue;
-		else {
-			page_no = bt_getid(bt->page->right);
-			parent = 0;
+		else
 			goto slideright;
-		}
 
-	  page_no = bt_getid(slotptr(bt->page, slot)->id);
-	  parent = 1;
+	  page_no = bt_getid(slotptr(set->page, slot)->id);
 	  drill--;
-	}
+	  continue;
+	 }
 
 	//  or slide right into next page
 
-	else {
-		page_no = bt_getid(bt->page->right);
-		parent = 0;
-	}
-
-	//  continue down / right using overlapping locks
-	//  to protect pages being split.
-
 slideright:
-	prevpage = bt->page_no;
-	prevpool = bt->pool;
-	prevset = bt->set;
-	prevmode = mode;
+	page_no = bt_getid(set->page->right);
+
   } while( page_no );
 
   // return error on end of right chain
@@ -1507,410 +1457,262 @@ slideright:
   return 0;	// return error
 }
 
-//  remove empty page from the B-tree
-//	by pulling our right node left over ourselves
-
-//  call with bt->page, etc, set to page's locked parent
-//	returns with page locked.
+//	return page to free list
+//	page must be delete & write locked
 
-BTERR bt_mergeright (BtDb *bt, BtPage page, BtPool *pool, BtLatchSet *set, uid page_no, uint lvl, uint slot)
+void bt_freepage (BtDb *bt, BtPageSet *set)
 {
-BtLatchSet *rset, *pset, *rpset;
-BtPool *rpool, *ppool, *rppool;
-BtPage rpage, ppage, rppage;
-uid right, parent, rparent;
-BtKey ptr;
-uint idx;
-
-	//	cache node's parent page
-
-	parent = bt->page_no;
-	ppage = bt->page;
-	ppool = bt->pool;
-	pset = bt->set;
-
-	// lock and map our right page
-	//	it cannot be NULL because of the stopper
-	//	in the last right page
-
-	bt_lockpage (BtLockWrite, set);
-
-	// if we aren't dead yet
-
-	if( page->act )
-		goto rmergexit;
-
-	if( right = bt_getid (page->right) )
-	  if( rpool = bt_pinpool (bt, right) )
-		rpage = bt_page (bt, rpool, right);
-	  else
-		return bt->err;
-	else
-		return bt->err = BTERR_struct;
-
-	rset = bt_pinlatch (bt, right);
-
-	//	find our right neighbor
-
-	if( ppage->act > 1 ) {
-	 for( idx = slot; idx++ < ppage->cnt; )
-	  if( !slotptr(ppage, idx)->dead )
-		break;
-
-	 if( idx > ppage->cnt )
-		return bt->err = BTERR_struct;
-
-	 //  redirect right neighbor in parent to left node
-
-	 bt_putid(slotptr(ppage,idx)->id, page_no);
-	}
-
-	//	if parent has only our deleted page, e.g. no right neighbor
-	//	prepare to merge parent itself
-
-	if( ppage->act == 1 ) {
-	  if( rparent = bt_getid (ppage->right) )
-	   if( rppool = bt_pinpool (bt, rparent) )
-		rppage = bt_page (bt, rppool, rparent);
-	   else
-		return bt->err;
-	  else
-		return bt->err = BTERR_struct;
-
-	  rpset = bt_pinlatch (bt, rparent);
-	  bt_lockpage (BtLockWrite, rpset);
-
-	  // find our right neighbor on right parent page
-
-	  for( idx = 0; idx++ < rppage->cnt; )
-		if( !slotptr(rppage, idx)->dead ) {
-		  bt_putid (slotptr(rppage, idx)->id, page_no);
-		  break;
-		}
-
-	  if( idx > rppage->cnt )
-		return bt->err = BTERR_struct;
-	}
+	//	lock allocation page
 
-	//	now that there are no more pointers to our right node
-	//	we can wait for delete lock on it
+	bt_spinwritelock (bt->mgr->latchmgr->lock);
 
-	bt_lockpage(BtLockDelete, rset);
-	bt_lockpage(BtLockWrite, rset);
+	//	store chain in second right
+	bt_putid(set->page->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+	bt_putid(bt->mgr->latchmgr->alloc[1].right, set->page_no);
+	set->page->free = 1;
 
-	// pull contents of right page into our empty page 
+	// unlock released page
 
-	memcpy (page, rpage, bt->mgr->page_size);
+	bt_unlockpage (BtLockDelete, set->latch);
+	bt_unlockpage (BtLockWrite, set->latch);
+	bt_unpinlatch (set->latch);
+	bt_unpinpool (set->pool);
 
-	// ready to release right parent lock
-	//	now that we have a new page in place
+	// unlock allocation page
 
-	if( ppage->act == 1 ) {
-	  bt_unlockpage (BtLockWrite, rpset);
-	  bt_unpinlatch (rpset);
-	  bt_unpinpool (rppool);
-	}
+	bt_spinreleasewrite (bt->mgr->latchmgr->lock);
+}
 
-	//	add killed right block to free chain
-	//	lock latch mgr
+//	a fence key was deleted from a page
+//	push new fence value upwards
 
-	bt_spinwritelock(bt->mgr->latchmgr->lock);
+BTERR bt_fixfence (BtDb *bt, BtPageSet *set, uint lvl)
+{
+unsigned char leftkey[256], rightkey[256];
+uid page_no;
+BtKey ptr;
 
-	//	store free chain in allocation page second right
+	//	remove the old fence value
 
-	bt_putid(rpage->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
-	bt_putid(bt->mgr->latchmgr->alloc[1].right, right);
+	ptr = keyptr(set->page, set->page->cnt);
+	memcpy (rightkey, ptr, ptr->len + 1);
 
-	// unlock latch mgr and right page
+	memset (slotptr(set->page, set->page->cnt--), 0, sizeof(BtSlot));
+	set->page->dirty = 1;
 
-	bt_unlockpage(BtLockDelete, rset);
-	bt_unlockpage(BtLockWrite, rset);
-	bt_unpinlatch (rset);
-	bt_unpinpool (rpool);
+	ptr = keyptr(set->page, set->page->cnt);
+	memcpy (leftkey, ptr, ptr->len + 1);
+	page_no = set->page_no;
 
-	bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+	bt_lockpage (BtLockParent, set->latch);
+	bt_unlockpage (BtLockWrite, set->latch);
 
-	// delete our obsolete fence key from our parent
+	//	insert new (now smaller) fence key
 
-	slotptr(ppage, slot)->dead = 1;
- 	ppage->dirty = 1;
+	if( bt_insertkey (bt, leftkey+1, *leftkey, lvl+1, page_no, time(NULL)) )
+	  return bt->err;
 
-	//	if our parent now empty
-	//	remove it from the tree
+	//	now delete old fence key
 
-	if( ppage->act-- == 1 )
- 	  if( bt_mergeleft (bt, ppage, ppool, pset, parent, lvl+1) )
+	if( bt_deletekey (bt, rightkey+1, *rightkey, lvl+1) )
 		return bt->err;
 
-rmergexit:
-	bt_unlockpage (BtLockWrite, pset);
-	bt_unpinlatch (pset);
-	bt_unpinpool (ppool);
-
-	bt->found = 1;
-	return bt->err = 0;
+	bt_unlockpage (BtLockParent, set->latch);
+	bt_unpinlatch(set->latch);
+	bt_unpinpool (set->pool);
+	return 0;
 }
 
-//  remove empty page from the B-tree
-//	try merging left first.  If no left
-//	sibling, then merge right.
-
-//	call with page loaded and locked,
-//  return with page locked.
+//	root has a single child
+//	collapse a level from the tree
 
-BTERR bt_mergeleft (BtDb *bt, BtPage page, BtPool *pool, BtLatchSet *set, uid page_no, uint lvl)
+BTERR bt_collapseroot (BtDb *bt, BtPageSet *root)
 {
-unsigned char fencekey[256], postkey[256];
-uint slot, idx, postfence = 0;
-BtLatchSet *lset, *pset;
-BtPool *lpool, *ppool;
-BtPage lpage, ppage;
-uid left, parent;
-BtKey ptr;
-
-	ptr = keyptr(page, page->cnt);
-	memcpy(fencekey, ptr, ptr->len + 1);
-	bt_unlockpage (BtLockWrite, set);
-
-	//	load and lock our parent
-
-retry:
-	if( !(slot = bt_loadpage (bt, fencekey+1, *fencekey, lvl+1, BtLockWrite)) )
-		return bt->err;
-
-	parent = bt->page_no;
-	ppage = bt->page;
-	ppool = bt->pool;
-	pset = bt->set;
-
-	//	wait until we are posted in our parent
-
-	if( !bt->parent ) {
-		bt_unlockpage (BtLockWrite, pset);
-		bt_unpinlatch (pset);
-		bt_unpinpool (ppool);
-#ifdef unix
-		sched_yield();
-#else
-		SwitchToThread();
-#endif
-		goto retry;
-	}
+BtPageSet child[1];
+uint idx;
 
-	//  find our left neighbor in our parent page
+  // find the child entry and promote as new root contents
 
-	for( idx = slot; --idx; )
-	  if( !slotptr(ppage, idx)->dead )
+  do {
+	for( idx = 0; idx++ < root->page->cnt; )
+	  if( !slotptr(root->page, idx)->dead )
 		break;
 
-	//	if no left neighbor, do right merge
-
-	if( !idx )
-		return bt_mergeright (bt, page, pool, set, page_no, lvl, slot);
-
-	// lock and map our left neighbor's page
+	child->page_no = bt_getid (slotptr(root->page, idx)->id);
 
-	left = bt_getid (slotptr(ppage, idx)->id);
+	child->latch = bt_pinlatch (bt, child->page_no);
+	bt_lockpage (BtLockDelete, child->latch);
+	bt_lockpage (BtLockWrite, child->latch);
 
-	if( lpool = bt_pinpool (bt, left) )
-		lpage = bt_page (bt, lpool, left);
+	if( child->pool = bt_pinpool (bt, child->page_no) )
+		child->page = bt_page (bt, child->pool, child->page_no);
 	else
 		return bt->err;
 
-	lset = bt_pinlatch (bt, left);
-	bt_lockpage(BtLockWrite, lset);
+	memcpy (root->page, child->page, bt->mgr->page_size);
+	bt_freepage (bt, child);
 
-	//  wait until sibling is in our parent
-
-	if( bt_getid (lpage->right) != page_no ) {
-		bt_unlockpage (BtLockWrite, pset);
-		bt_unpinlatch (pset);
-		bt_unpinpool (ppool);
-		bt_unlockpage (BtLockWrite, lset);
-		bt_unpinlatch (lset);
-		bt_unpinpool (lpool);
-#ifdef linux
-		sched_yield();
-#else
-		SwitchToThread();
-#endif
-		goto retry;
-	}
+  } while( root->page->lvl > 1 && root->page->act == 1 );
 
-	//  since our page will have no more pointers to it,
-	//	obtain Delete lock and wait for write locks to clear
-
-	bt_lockpage(BtLockDelete, set);
-	bt_lockpage(BtLockWrite, set);
+  bt_unlockpage (BtLockWrite, root->latch);
+  bt_unpinlatch (root->latch);
+  bt_unpinpool (root->pool);
+  return 0;
+}
 
-	//	if we aren't dead yet,
-	//	get ready for exit
+//  find and delete key on page by marking delete flag bit
+//  if page becomes empty, delete it from the btree
 
-	if( page->act ) {
-		bt_unlockpage(BtLockDelete, set);
-		bt_unlockpage(BtLockWrite, lset);
-		bt_unpinlatch (lset);
-		bt_unpinpool (lpool);
-		goto lmergexit;
-	}
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+{
+unsigned char lowerfence[256], higherfence[256];
+uint slot, idx, dirty = 0, fence, found;
+BtPageSet set[1], right[1];
+BtKey ptr;
 
-	//	are we are the fence key for our parent?
-	//	if so, grab our old fence key
+	if( slot = bt_loadpage (bt, set, key, len, lvl, BtLockWrite) )
+		ptr = keyptr(set->page, slot);
+	else
+		return bt->err;
 
-	if( postfence = slot == ppage->cnt ) {
-		ptr = keyptr (ppage, ppage->cnt);
-		memcpy(fencekey, ptr, ptr->len + 1);
-		memset(slotptr(ppage, ppage->cnt), 0, sizeof(BtSlot));
+	//	are we deleting a fence slot?
 
-		// clear out other dead slots
+	fence = slot == set->page->cnt;
 
-		while( --ppage->cnt )
-		  if( slotptr(ppage, ppage->cnt)->dead )
-			memset(slotptr(ppage, ppage->cnt), 0, sizeof(BtSlot));
-		  else
-			break;
+	// if key is found delete it, otherwise ignore request
 
-		ptr = keyptr (ppage, ppage->cnt);
-		memcpy(postkey, ptr, ptr->len + 1);
-	} else
-		slotptr(ppage,slot)->dead = 1;
+	if( found = !keycmp (ptr, key, len) )
+	  if( found = slotptr(set->page, slot)->dead == 0 ) {
+		dirty = slotptr(set->page, slot)->dead = 1;
+ 		set->page->dirty = 1;
+ 		set->page->act--;
 
-	ppage->dirty = 1;
-	ppage->act--;
+		// collapse empty slots
 
-	//	push our right neighbor pointer to our left
+		while( idx = set->page->cnt - 1 )
+		  if( slotptr(set->page, idx)->dead ) {
+			*slotptr(set->page, idx) = *slotptr(set->page, idx + 1);
+			memset (slotptr(set->page, set->page->cnt--), 0, sizeof(BtSlot));
+		  } else
+			break;
+		  }
 
-	memcpy (lpage->right, page->right, BtId);
+	//	did we delete a fence key in an upper level?
 
-	//	add ourselves to free chain
-	//	lock latch mgr
+	if( dirty && lvl && set->page->act && fence )
+	  if( bt_fixfence (bt, set, lvl) )
+		return bt->err;
+	  else
+		return bt->found = found, 0;
 
-	bt_spinwritelock(bt->mgr->latchmgr->lock);
+	//	is this a collapsed root?
 
-	//	store free chain in allocation page second right
-	bt_putid(page->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
-	bt_putid(bt->mgr->latchmgr->alloc[1].right, page_no);
+	if( lvl > 1 && set->page_no == ROOT_page && set->page->act == 1 )
+	  if( bt_collapseroot (bt, set) )
+		return bt->err;
+	  else
+		return bt->found = found, 0;
 
-	// unlock latch mgr and pages
+	//	return if page is not empty
 
-	bt_spinreleasewrite(bt->mgr->latchmgr->lock);
-	bt_unlockpage(BtLockWrite, lset);
-	bt_unpinlatch (lset);
-	bt_unpinpool (lpool);
+ 	if( set->page->act ) {
+		bt_unlockpage(BtLockWrite, set->latch);
+		bt_unpinlatch (set->latch);
+		bt_unpinpool (set->pool);
+		return bt->found = found, 0;
+	}
 
-	// release our node's delete lock
+	//	cache copy of fence key
+	//	to post in parent
 
-	bt_unlockpage(BtLockDelete, set);
+	ptr = keyptr(set->page, set->page->cnt);
+	memcpy (lowerfence, ptr, ptr->len + 1);
 
-lmergexit:
-	bt_unlockpage (BtLockWrite, pset);
-	bt_unpinpool (ppool);
+	//	obtain lock on right page
 
-	//  do we need to post parent's fence key in its parent?
+	right->page_no = bt_getid(set->page->right);
+	right->latch = bt_pinlatch (bt, right->page_no);
+	bt_lockpage (BtLockWrite, right->latch);
 
-	if( !postfence || parent == ROOT_page ) {
-		bt_unpinlatch (pset);
-		bt->found = 1;
-		return bt->err = 0;
-	}
+	// pin page contents
 
-	//	interlock parent fence post
+	if( right->pool = bt_pinpool (bt, right->page_no) )
+		right->page = bt_page (bt, right->pool, right->page_no);
+	else
+		return 0;
 
-	bt_lockpage (BtLockParent, pset);
+	if( right->page->kill )
+		return bt->err = BTERR_struct;
 
-	//	load parent's parent page
-posttry:
-	if( !(slot = bt_loadpage (bt, fencekey+1, *fencekey, lvl+2, BtLockWrite)) )
-		return bt->err;
+	// pull contents of right peer into our empty page
 
- 	if( !(slot = bt_cleanpage (bt, bt->page, *fencekey, slot)) )
-	  if( bt_splitpage (bt, bt->page, bt->pool, bt->set, bt->page_no) )
-		return bt->err;
-	  else
-		goto posttry;
+	memcpy (set->page, right->page, bt->mgr->page_size);
 
-	page = bt->page;
+	// cache copy of key to update
 
-	page->min -= *postkey + 1;
-	((unsigned char *)page)[page->min] = *postkey;
-	memcpy ((unsigned char *)page + page->min +1, postkey + 1, *postkey );
-	slotptr(page, slot)->off = page->min;
+	ptr = keyptr(right->page, right->page->cnt);
+	memcpy (higherfence, ptr, ptr->len + 1);
 
-	bt_unlockpage (BtLockParent, pset);
-	bt_unpinlatch (pset);
+	// mark right page deleted and point it to left page
+	//	until we can post parent updates
 
-	bt_unlockpage (BtLockWrite, bt->set);
-	bt_unpinlatch (bt->set);
-	bt_unpinpool (bt->pool);
+	bt_putid (right->page->right, set->page_no);
+	right->page->kill = 1;
 
-	bt->found = 1;
-	return bt->err = 0;
-}
+	bt_lockpage (BtLockParent, right->latch);
+	bt_unlockpage (BtLockWrite, right->latch);
 
-//  find and delete key on page by marking delete flag bit
-//  if page becomes empty, delete it from the btree
+	bt_lockpage (BtLockParent, set->latch);
+	bt_unlockpage (BtLockWrite, set->latch);
 
-BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
-{
-BtLatchSet *set;
-BtPool *pool;
-BtPage page;
-uid page_no;
-BtKey ptr;
-uint slot;
+	// redirect higher key directly to our new node contents
 
-	if( !(slot = bt_loadpage (bt, key, len, 0, BtLockWrite)) )
-		return bt->err;
+	if( bt_insertkey (bt, higherfence+1, *higherfence, lvl+1, set->page_no, time(NULL)) )
+	  return bt->err;
 
-	page_no = bt->page_no;
-	page = bt->page;
-	pool = bt->pool;
-	set = bt->set;
+	//	delete old lower key to our node
 
-	// if key is found delete it, otherwise ignore request
+	if( bt_deletekey (bt, lowerfence+1, *lowerfence, lvl+1) )
+	  return bt->err;
 
-	ptr = keyptr(page, slot);
+	//	obtain delete and write locks to right node
 
-	if( bt->found = !keycmp (ptr, key, len) )
-	  if( bt->found = slotptr(page, slot)->dead == 0 ) {
- 		slotptr(page,slot)->dead = 1;
-		  if( slot < page->cnt )
- 			page->dirty = 1;
- 		  if( !--page->act )
-	  		if( bt_mergeleft (bt, page, pool, set, page_no, 0) )
-			  return bt->err;
-		}
+	bt_unlockpage (BtLockParent, right->latch);
+	bt_lockpage (BtLockDelete, right->latch);
+	bt_lockpage (BtLockWrite, right->latch);
+	bt_freepage (bt, right);
 
-	bt_unlockpage(BtLockWrite, set);
-	bt_unpinlatch (set);
-	bt_unpinpool (pool);
-	return bt->err = 0;
+	bt_unlockpage (BtLockParent, set->latch);
+	bt_unpinlatch (set->latch);
+	bt_unpinpool (set->pool);
+	bt->found = found;
+	return 0;
 }
 
 //	find key in leaf level and return row-id
 
 uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
 {
+BtPageSet set[1];
 uint  slot;
+uid id = 0;
 BtKey ptr;
-uid id;
 
-	if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
-		ptr = keyptr(bt->page, slot);
+	if( slot = bt_loadpage (bt, set, key, len, 0, BtLockRead) )
+		ptr = keyptr(set->page, slot);
 	else
 		return 0;
 
 	// if key exists, return row-id
 	//	otherwise return 0
 
-	if( slot <= bt->page->cnt && !keycmp (ptr, key, len) )
-		id = bt_getid(slotptr(bt->page,slot)->id);
-	else
-		id = 0;
+	if( slot <= set->page->cnt )
+	  if( !keycmp (ptr, key, len) )
+		id = bt_getid(slotptr(set->page,slot)->id);
 
-	bt_unlockpage (BtLockRead, bt->set);
-	bt_unpinlatch (bt->set);
-	bt_unpinpool (bt->pool);
+	bt_unlockpage (BtLockRead, set->latch);
+	bt_unpinlatch (set->latch);
+	bt_unpinpool (set->pool);
 	return id;
 }
 
@@ -1944,9 +1746,7 @@ BtKey key;
 	page->act = 0;
 
 	// try cleaning up page first
-
-	// always leave fence key in the array
-	// otherwise, remove deleted key
+	// by removing deleted keys
 
 	while( cnt++ < max ) {
 		if( cnt == slot )
@@ -1954,13 +1754,14 @@ BtKey key;
 		if( cnt < max && slotptr(bt->frame,cnt)->dead )
 			continue;
 
-		// copy key
+		// copy the key across
 
 		key = keyptr(bt->frame, cnt);
 		nxt -= key->len + 1;
 		memcpy ((unsigned char *)page + nxt, key, key->len + 1);
 
 		// copy slot
+
 		memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
 		if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
 			page->act++;
@@ -1979,253 +1780,235 @@ BtKey key;
 	return 0;
 }
 
-//	add key to current page
-//	page must already be writelocked
+// split the root and raise the height of the btree
 
-void bt_addkeytopage (BtDb *bt, BtPage page, uint slot, unsigned char *key, uint len, uid id, uint tod)
-{
-uint idx;
-
-	// find next available dead slot and copy key onto page
-
-	for( idx = slot; idx < page->cnt; idx++ )
-	  if( slotptr(page, idx)->dead )
-		break;
-
-	if( idx == page->cnt )
-		idx++, page->cnt++;
-
-	page->act++;
-
-	// now insert key into array before slot
-
-	while( idx > slot )
-		*slotptr(page, idx) = *slotptr(page, idx -1), idx--;
-
-	page->min -= len + 1;
-	((unsigned char *)page)[page->min] = len;
-	memcpy ((unsigned char *)page + page->min +1, key, len );
-
-	bt_putid(slotptr(page,slot)->id, id);
-	slotptr(page, slot)->off = page->min;
-	slotptr(page, slot)->tod = tod;
-	slotptr(page, slot)->dead = 0;
-}
-
-BTERR bt_splitroot(BtDb *bt, unsigned char *leftkey, uid page_no2)
+BTERR bt_splitroot(BtDb *bt, BtPageSet *root, unsigned char *leftkey, uid page_no2)
 {
 uint nxt = bt->mgr->page_size;
-BtPage root = bt->page;
-uid new_page;
+uid left;
 
 	//  Obtain an empty page to use, and copy the current
-	//  root contents into it
+	//  root contents into it, e.g. lower keys
 
-	if( !(new_page = bt_newpage(bt, root)) )
+	if( !(left = bt_newpage(bt, root->page)) )
 		return bt->err;
 
 	// preserve the page info at the bottom
-	// and set rest to zero
+	// of higher keys and set rest to zero
 
-	memset(root+1, 0, bt->mgr->page_size - sizeof(*root));
+	memset(root->page+1, 0, bt->mgr->page_size - sizeof(*root->page));
 
-	// insert first key on newroot page
+	// insert lower keys page fence key on newroot page as first key
 
 	nxt -= *leftkey + 1;
-	memcpy ((unsigned char *)root + nxt, leftkey, *leftkey + 1);
-	bt_putid(slotptr(root, 1)->id, new_page);
-	slotptr(root, 1)->off = nxt;
+	memcpy ((unsigned char *)root->page + nxt, leftkey, *leftkey + 1);
+	bt_putid(slotptr(root->page, 1)->id, left);
+	slotptr(root->page, 1)->off = nxt;
 	
-	// insert second key (stopper key) on newroot page
+	// insert stopper key on newroot page
 	// and increase the root height
 
 	nxt -= 3;
-	*((unsigned char *)root + nxt) = 2;
-	memset ((unsigned char *)root + nxt + 1, 0xff, 2);
-	bt_putid(slotptr(root, 2)->id, page_no2);
-	slotptr(root, 2)->off = nxt;
-
-	bt_putid(root->right, 0);
-	root->min = nxt;		// reset lowest used offset and key count
-	root->cnt = 2;
-	root->act = 2;
-	root->lvl++;
-
-	// release and unpin root (bt->page)
-
-	bt_unlockpage(BtLockWrite, bt->set);
-	bt_unpinlatch (bt->set);
-	bt_unpinpool (bt->pool);
+	((unsigned char *)root->page)[nxt] = 2;
+	((unsigned char *)root->page)[nxt+1] = 0xff;
+	((unsigned char *)root->page)[nxt+2] = 0xff;
+	bt_putid(slotptr(root->page, 2)->id, page_no2);
+	slotptr(root->page, 2)->off = nxt;
+
+	bt_putid(root->page->right, 0);
+	root->page->min = nxt;		// reset lowest used offset and key count
+	root->page->cnt = 2;
+	root->page->act = 2;
+	root->page->lvl++;
+
+	// release and unpin root
+
+	bt_unlockpage(BtLockWrite, root->latch);
+	bt_unpinlatch (root->latch);
+	bt_unpinpool (root->pool);
 	return 0;
 }
 
 //  split already locked full node
-//	return unlocked and unpinned.
+//	return unlocked.
 
-BTERR bt_splitpage (BtDb *bt, BtPage page, BtPool *pool, BtLatchSet *set, uid page_no)
+BTERR bt_splitpage (BtDb *bt, BtPageSet *set)
 {
-uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
-unsigned char rightkey[256], leftkey[256];
-uint tod = time(NULL);
-uint lvl = page->lvl;
-uid new_page;
+uint cnt = 0, idx = 0, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256], rightkey[256];
+uint lvl = set->page->lvl;
+BtPageSet right[1];
+uint prev;
 BtKey key;
 
-	//	initialize frame buffer for right node
+	//  split higher half of keys to bt->frame
 
 	memset (bt->frame, 0, bt->mgr->page_size);
-	max = page->cnt;
+	max = set->page->cnt;
 	cnt = max / 2;
 	idx = 0;
 
-	//  split higher half of keys to bt->frame
-
 	while( cnt++ < max ) {
-		key = keyptr(page, cnt);
+		key = keyptr(set->page, cnt);
 		nxt -= key->len + 1;
 		memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
-		memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
-		if( !(slotptr(bt->frame, idx)->dead = slotptr(page, cnt)->dead) )
+
+		memcpy(slotptr(bt->frame,++idx)->id, slotptr(set->page,cnt)->id, BtId);
+		if( !(slotptr(bt->frame, idx)->dead = slotptr(set->page, cnt)->dead) )
 			bt->frame->act++;
-		slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+		slotptr(bt->frame, idx)->tod = slotptr(set->page, cnt)->tod;
 		slotptr(bt->frame, idx)->off = nxt;
 	}
 
-	// transfer right link node to new right node
+	// remember existing fence key for new page to the right
 
-	if( page_no > ROOT_page )
-		memcpy (bt->frame->right, page->right, BtId);
+	memcpy (rightkey, key, key->len + 1);
 
 	bt->frame->bits = bt->mgr->page_bits;
 	bt->frame->min = nxt;
 	bt->frame->cnt = idx;
 	bt->frame->lvl = lvl;
 
-	//	get new free page and write right frame to it.
+	// link right node
 
-	if( !(new_page = bt_newpage(bt, bt->frame)) )
-		return bt->err;
+	if( set->page_no > ROOT_page )
+		memcpy (bt->frame->right, set->page->right, BtId);
 
-	//	remember fence key for new right page to add
-	//	as right sibling to the left node
+	//	get new free page and write higher keys to it.
 
-	key = keyptr(bt->frame, idx);
-	memcpy (rightkey, key, key->len + 1);
+	if( !(right->page_no = bt_newpage(bt, bt->frame)) )
+		return bt->err;
 
 	//	update lower keys to continue in old page
 
-	memcpy (bt->frame, page, bt->mgr->page_size);
-	memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+	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;
-	page->dirty = 0;
-	page->act = 0;
+	set->page->dirty = 0;
+	set->page->act = 0;
 	cnt = 0;
 	idx = 0;
 
 	//  assemble page of smaller keys
-	//	to remain in the old page
 
 	while( cnt++ < max / 2 ) {
 		key = keyptr(bt->frame, cnt);
 		nxt -= key->len + 1;
-		memcpy ((unsigned char *)page + nxt, key, key->len + 1);
-		memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
-		if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
-			page->act++;
-		slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
-		slotptr(page, idx)->off = nxt;
+		memcpy ((unsigned char *)set->page + nxt, key, key->len + 1);
+		memcpy(slotptr(set->page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+		slotptr(set->page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+		slotptr(set->page, idx)->off = nxt;
+		set->page->act++;
 	}
 
-	// finalize left page and save fence key
-
-	memcpy(leftkey, key, key->len + 1);
-	page->min = nxt;
-	page->cnt = idx;
+	// remember fence key for smaller page
 
-	//	link new right page
+	memcpy(fencekey, key, key->len + 1);
 
-	bt_putid (page->right, new_page);
+	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( page_no == ROOT_page )
-		return bt_splitroot (bt, leftkey, new_page);
+	if( set->page_no == ROOT_page )
+		return bt_splitroot (bt, set, fencekey, right->page_no);
 
-	//  obtain ParentModification lock for current page
+	// insert new fences in their parent pages
 
-	bt_lockpage (BtLockParent, set);
+	right->latch = bt_pinlatch (bt, right->page_no);
+	bt_lockpage (BtLockParent, right->latch);
 
-	//  release wr lock on our page.
-	//	this will keep out another SMO
+	bt_lockpage (BtLockParent, set->latch);
+	bt_unlockpage (BtLockWrite, set->latch);
 
-	bt_unlockpage (BtLockWrite, set);
+	// insert new fence for reformulated left block of smaller keys
 
-	//  insert key for old page (lower keys)
-
-	if( bt_insertkey (bt, leftkey + 1, *leftkey, page_no, tod, lvl + 1) )
+	if( bt_insertkey (bt, fencekey+1, *fencekey, lvl+1, set->page_no, time(NULL)) )
 		return bt->err;
 
-	//	switch old parent key from us to our right page
+	// switch fence for right block of larger keys to new right page
 
-	if( bt_insertkey (bt, rightkey + 1, *rightkey, new_page, tod, lvl + 1) )
+	if( bt_insertkey (bt, rightkey+1, *rightkey, lvl+1, right->page_no, time(NULL)) )
 		return bt->err;
 
-	//	unlock and unpin
+	bt_unlockpage (BtLockParent, set->latch);
+	bt_unpinlatch (set->latch);
+	bt_unpinpool (set->pool);
 
-	bt_unlockpage (BtLockParent, set);
-	bt_unpinlatch (set);
-	bt_unpinpool (pool);
+	bt_unlockpage (BtLockParent, right->latch);
+	bt_unpinlatch (right->latch);
 	return 0;
 }
-
 //  Insert new key into the btree at given level.
 
-BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl)
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uint lvl, uid id, uint tod)
 {
+BtPageSet set[1];
 uint slot, idx;
-BtPage page;
 BtKey ptr;
 
 	while( 1 ) {
-		if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
-			ptr = keyptr(bt->page, slot);
+		if( slot = bt_loadpage (bt, set, key, len, lvl, BtLockWrite) )
+			ptr = keyptr(set->page, slot);
 		else
 		{
-			if ( !bt->err )
+			if( !bt->err )
 				bt->err = BTERR_ovflw;
 			return bt->err;
 		}
 
 		// if key already exists, update id and return
 
-		page = bt->page;
-
 		if( !keycmp (ptr, key, len) ) {
-			if( slotptr(page, slot)->dead )
-				page->act++;
-			slotptr(page, slot)->dead = 0;
-			slotptr(page, slot)->tod = tod;
-			bt_putid(slotptr(page,slot)->id, id);
-			bt_unlockpage(BtLockWrite, bt->set);
-			bt_unpinlatch (bt->set);
-			bt_unpinpool (bt->pool);
-			return bt->err;
+			if( slotptr(set->page, slot)->dead )
+				set->page->act++;
+			slotptr(set->page, slot)->dead = 0;
+			slotptr(set->page, slot)->tod = tod;
+			bt_putid(slotptr(set->page,slot)->id, id);
+			bt_unlockpage(BtLockWrite, set->latch);
+			bt_unpinlatch (set->latch);
+			bt_unpinpool (set->pool);
+			return 0;
 		}
 
 		// check if page has enough space
 
- 		if( slot = bt_cleanpage (bt, bt->page, len, slot) )
+ 		if( slot = bt_cleanpage (bt, set->page, len, slot) )
 			break;
 
-		if( bt_splitpage (bt, bt->page, bt->pool, bt->set, bt->page_no) )
+		if( bt_splitpage (bt, set) )
 			return bt->err;
 	}
 
-  	bt_addkeytopage (bt, bt->page, slot, key, len, id, tod);
+	// calculate next available slot and copy key into page
+
+	set->page->min -= len + 1; // reset lowest used offset
+	((unsigned char *)set->page)[set->page->min] = len;
+	memcpy ((unsigned char *)set->page + set->page->min +1, key, len );
+
+	for( idx = slot; idx < set->page->cnt; idx++ )
+	  if( slotptr(set->page, idx)->dead )
+		break;
+
+	// now insert key into array before slot
 
-	bt_unlockpage (BtLockWrite, bt->set);
-	bt_unpinlatch (bt->set);
-	bt_unpinpool (bt->pool);
+	if( idx == set->page->cnt )
+		idx++, set->page->cnt++;
+
+	set->page->act++;
+
+	while( idx > slot )
+		*slotptr(set->page, idx) = *slotptr(set->page, idx -1), idx--;
+
+	bt_putid(slotptr(set->page,slot)->id, id);
+	slotptr(set->page, slot)->off = set->page->min;
+	slotptr(set->page, slot)->tod = tod;
+	slotptr(set->page, slot)->dead = 0;
+
+	bt_unlockpage (BtLockWrite, set->latch);
+	bt_unpinlatch (set->latch);
+	bt_unpinpool (set->pool);
 	return 0;
 }
 
@@ -2233,17 +2016,21 @@ BtKey ptr;
 
 uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
 {
+BtPageSet set[1];
 uint slot;
 
 	// cache page for retrieval
-	if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
-		memcpy (bt->cursor, bt->page, bt->mgr->page_size);
 
-	bt->cursor_page = bt->page_no;
+	if( slot = bt_loadpage (bt, set, key, len, 0, BtLockRead) )
+	  memcpy (bt->cursor, set->page, bt->mgr->page_size);
+	else
+	  return 0;
+
+	bt->cursor_page = set->page_no;
 
-	bt_unlockpage(BtLockRead, bt->set);
-	bt_unpinlatch (bt->set);
-	bt_unpinpool (bt->pool);
+	bt_unlockpage(BtLockRead, set->latch);
+	bt_unpinlatch (set->latch);
+	bt_unpinpool (set->pool);
 	return slot;
 }
 
@@ -2252,17 +2039,16 @@ uint slot;
 
 uint bt_nextkey (BtDb *bt, uint slot)
 {
-BtLatchSet *set;
-BtPool *pool;
-BtPage page;
+BtPageSet set[1];
 uid right;
 
   do {
 	right = bt_getid(bt->cursor->right);
+
 	while( slot++ < bt->cursor->cnt )
 	  if( slotptr(bt->cursor,slot)->dead )
 		continue;
-	  else if( right || (slot < bt->cursor->cnt) )
+	  else if( right || (slot < bt->cursor->cnt) ) // skip infinite stopper
 		return slot;
 	  else
 		break;
@@ -2271,20 +2057,22 @@ uid right;
 		break;
 
 	bt->cursor_page = right;
-	if( pool = bt_pinpool (bt, right) )
-		page = bt_page (bt, pool, right);
+
+	if( set->pool = bt_pinpool (bt, right) )
+		set->page = bt_page (bt, set->pool, right);
 	else
 		return 0;
 
-	set = bt_pinlatch (bt, right);
-    bt_lockpage(BtLockRead, set);
+	set->latch = bt_pinlatch (bt, right);
+    bt_lockpage(BtLockRead, set->latch);
 
-	memcpy (bt->cursor, page, bt->mgr->page_size);
+	memcpy (bt->cursor, set->page, bt->mgr->page_size);
 
-	bt_unlockpage(BtLockRead, set);
-	bt_unpinlatch (set);
-	bt_unpinpool (pool);
+	bt_unlockpage(BtLockRead, set->latch);
+	bt_unpinlatch (set->latch);
+	bt_unpinpool (set->pool);
 	slot = 0;
+
   } while( 1 );
 
   return bt->err = 0;
@@ -2305,53 +2093,134 @@ uint bt_tod(BtDb *bt, uint slot)
 	return slotptr(bt->cursor,slot)->tod;
 }
 
-
 #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
+
 void bt_latchaudit (BtDb *bt)
 {
 ushort idx, hashidx;
-BtLatchSet *set;
-BtPool *pool;
-BtPage page;
-uid page_no;
+uid next, page_no;
+BtLatchSet *latch;
+BtKey ptr;
 
 #ifdef unix
-	for( idx = 1; idx < bt->mgr->latchmgr->latchdeployed; idx++ ) {
-		set = bt->mgr->latchsets + idx;
-		if( *(ushort *)set->readwr || *(ushort *)set->access || *(ushort *)set->parent ) {
-			fprintf(stderr, "latchset %d locked for page %6x\n", idx, set->page_no);
-			*(ushort *)set->readwr = 0;
-			*(ushort *)set->access = 0;
-			*(ushort *)set->parent = 0;
-		}
-		if( set->pin ) {
-			fprintf(stderr, "latchset %d pinned\n", idx);
-			set->pin = 0;
+	if( *(uint *)(bt->mgr->latchmgr->lock) )
+		fprintf(stderr, "Alloc page locked\n");
+	*(uint *)(bt->mgr->latchmgr->lock) = 0;
+
+	for( idx = 1; idx <= bt->mgr->latchmgr->latchdeployed; idx++ ) {
+		latch = bt->mgr->latchsets + idx;
+		if( *(uint *)latch->readwr )
+			fprintf(stderr, "latchset %d rwlocked for page %.8x\n", idx, latch->page_no);
+		*(uint *)latch->readwr = 0;
+
+		if( *(uint *)latch->access )
+			fprintf(stderr, "latchset %d accesslocked for page %.8x\n", idx, latch->page_no);
+		*(uint *)latch->access = 0;
+
+		if( *(uint *)latch->parent )
+			fprintf(stderr, "latchset %d parentlocked for page %.8x\n", idx, latch->page_no);
+		*(uint *)latch->parent = 0;
+
+		if( latch->pin ) {
+			fprintf(stderr, "latchset %d pinned for page %.8x\n", idx, latch->page_no);
+			latch->pin = 0;
 		}
 	}
 
 	for( hashidx = 0; hashidx < bt->mgr->latchmgr->latchhash; hashidx++ ) {
-	  if( *(uint *)bt->mgr->latchmgr->table[hashidx].latch )
-		fprintf(stderr, "latchmgr locked\n");
+	  if( *(uint *)(bt->mgr->latchmgr->table[hashidx].latch) )
+			fprintf(stderr, "hash entry %d locked\n", hashidx);
+
+	  *(uint *)(bt->mgr->latchmgr->table[hashidx].latch) = 0;
+
 	  if( idx = bt->mgr->latchmgr->table[hashidx].slot ) do {
-		set = bt->mgr->latchsets + idx;
-		if( *(uint *)set->readwr || *(ushort *)set->access || *(ushort *)set->parent )
-			fprintf(stderr, "latchset %d locked\n", idx);
-		if( set->hash != hashidx )
+		latch = bt->mgr->latchsets + idx;
+		if( *(uint *)latch->busy )
+			fprintf(stderr, "latchset %d busylocked for page %.8x\n", idx, latch->page_no);
+		*(uint *)latch->busy = 0;
+		if( latch->hash != hashidx )
 			fprintf(stderr, "latchset %d wrong hashidx\n", idx);
-		if( set->pin )
-			fprintf(stderr, "latchset %d pinned\n", idx);
-	  } while( idx = set->next );
+		if( latch->pin )
+			fprintf(stderr, "latchset %d pinned for page %.8x\n", idx, latch->page_no);
+	  } while( idx = latch->next );
 	}
-	page_no = bt_getid(bt->mgr->latchmgr->alloc[1].right);
-
-	while( page_no ) {
-		fprintf(stderr, "free: %.6x\n", (uint)page_no);
-		pool = bt_pinpool (bt, page_no);
-		page = bt_page (bt, pool, page_no);
-	    page_no = bt_getid(page->right);
-		bt_unpinpool (pool);
+
+	next = bt->mgr->latchmgr->nlatchpage + LATCH_page;
+	page_no = LEAF_page;
+
+	while( page_no < bt_getid(bt->mgr->latchmgr->alloc->right) ) {
+		pread (bt->mgr->idx, bt->frame, bt->mgr->page_size, page_no << bt->mgr->page_bits);
+		if( !bt->frame->free )
+		 for( idx = 0; idx++ < bt->frame->cnt - 1; ) {
+		  ptr = keyptr(bt->frame, idx+1);
+		  if( keycmp (keyptr(bt->frame, idx), ptr->key, ptr->len) >= 0 )
+			fprintf(stderr, "page %.8x idx %.2x out of order\n", page_no, idx);
+		 }
+
+		if( page_no > LEAF_page )
+			next = page_no + 1;
+		page_no = next;
 	}
 #endif
 }
@@ -2377,10 +2246,8 @@ uid next, page_no = LEAF_page;	// start on first page of leaves
 unsigned char key[256];
 ThreadArg *args = arg;
 int ch, len = 0, slot;
-BtLatchSet *set;
+BtPageSet set[1];
 time_t tod[1];
-BtPool *pool;
-BtPage page;
 BtKey ptr;
 BtDb *bt;
 FILE *in;
@@ -2410,7 +2277,7 @@ FILE *in;
 			  else if( args->num )
 		  		sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
 
-			  if( bt_insertkey (bt, key, len, line, *tod, 0) )
+			  if( bt_insertkey (bt, key, len, 0, line, *tod) )
 				fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
 			  len = 0;
 			}
@@ -2432,7 +2299,7 @@ FILE *in;
 			  else if( args->num )
 		  		sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
 
-			  if( bt_deletekey (bt, key, len) )
+			  if( bt_deletekey (bt, key, len, 0) )
 				fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
 			  len = 0;
 			}
@@ -2466,40 +2333,61 @@ FILE *in;
 		break;
 
 	case 's':
-		len = key[0] = 0;
-
-		fprintf(stderr, "started reading\n");
-
-		if( slot = bt_startkey (bt, key, len) )
-		  slot--;
-		else
-		  fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
-
-		while( slot = bt_nextkey (bt, slot) ) {
-			ptr = bt_key(bt, slot);
-			fwrite (ptr->key, ptr->len, 1, stdout);
-			fputc ('\n', stdout);
-		}
+		fprintf(stderr, "started scanning\n");
+	  	do {
+			if( set->pool = bt_pinpool (bt, page_no) )
+				set->page = bt_page (bt, set->pool, page_no);
+			else
+				break;
+			set->latch = bt_pinlatch (bt, page_no);
+			bt_lockpage (BtLockRead, set->latch);
+			next = bt_getid (set->page->right);
+			cnt += set->page->act;
+
+			for( slot = 0; slot++ < set->page->cnt; )
+			 if( next || slot < set->page->cnt )
+			  if( !slotptr(set->page, slot)->dead ) {
+				ptr = keyptr(set->page, slot);
+				fwrite (ptr->key, ptr->len, 1, stdout);
+				fputc ('\n', stdout);
+			  }
+
+			bt_unlockpage (BtLockRead, set->latch);
+			bt_unpinlatch (set->latch);
+			bt_unpinpool (set->pool);
+	  	} while( page_no = next );
 
+	  	cnt--;	// remove stopper key
+		fprintf(stderr, " Total keys read %d\n", cnt);
 		break;
 
 	case 'c':
-		fprintf(stderr, "started reading\n");
+		fprintf(stderr, "started counting\n");
+		next = bt->mgr->latchmgr->nlatchpage + LATCH_page;
+		page_no = LEAF_page;
 
-	  	do {
-			if( pool = bt_pinpool (bt, page_no) )
-				page = bt_page (bt, pool, page_no);
-			else
-				break;
-			set = bt_pinlatch (bt, page_no);
-			bt_lockpage (BtLockRead, set);
-			cnt += page->act;
-			next = bt_getid (page->right);
-			bt_unlockpage (BtLockRead, set);
-			bt_unpinlatch (set);
-			bt_unpinpool (pool);
-	  	} while( page_no = next );
+		while( page_no < bt_getid(bt->mgr->latchmgr->alloc->right) ) {
+		uid off = page_no << bt->mgr->page_bits;
+#ifdef unix
+		  pread (bt->mgr->idx, bt->frame, bt->mgr->page_size, off);
+#else
+		DWORD amt[1];
+
+		  SetFilePointer (bt->mgr->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
 
+		  if( !ReadFile(bt->mgr->idx, bt->frame, bt->mgr->page_size, amt, NULL))
+			return bt->err = BTERR_map;
+
+		  if( *amt <  bt->mgr->page_size )
+			return bt->err = BTERR_map;
+#endif
+			if( !bt->frame->free && !bt->frame->lvl )
+				cnt += bt->frame->act;
+			if( page_no > LEAF_page )
+				next = page_no + 1;
+			page_no = next;
+		}
+		
 	  	cnt--;	// remove stopper key
 		fprintf(stderr, " Total keys read %d\n", cnt);
 		break;
@@ -2519,16 +2407,15 @@ int main (int argc, char **argv)
 {
 int idx, cnt, len, slot, err;
 int segsize, bits = 16;
+double start, stop;
 #ifdef unix
 pthread_t *threads;
-timer start, stop;
 #else
-time_t start[1], stop[1];
 HANDLE *threads;
 #endif
-double real_time;
 ThreadArg *args;
 uint poolsize = 0;
+float elapsed;
 int num = 0;
 char key[1];
 BtMgr *mgr;
@@ -2545,11 +2432,7 @@ BtDb *bt;
 		exit(0);
 	}
 
-#ifdef unix
-	gettimeofday(&start, NULL);
-#else
-	time(start);
-#endif
+	start = getCpuTime(0);
 
 	if( argc > 3 )
 		bits = atoi(argv[3]);
@@ -2607,18 +2490,20 @@ BtDb *bt;
 #ifdef unix
 	for( idx = 0; idx < cnt; idx++ )
 		pthread_join (threads[idx], NULL);
-	gettimeofday(&stop, NULL);
-	real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
 #else
 	WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
 
 	for( idx = 0; idx < cnt; idx++ )
 		CloseHandle(threads[idx]);
 
-	time (stop);
-	real_time = 1000 * (*stop - *start);
 #endif
-	fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+	elapsed = getCpuTime(0) - 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);
+
 	bt_mgrclose (mgr);
 }