]> pd.if.org Git - btree/blobdiff - threads2i.c
Fix small bug in main when there is less t han one input file
[btree] / threads2i.c
index 5f003793424653ad07bc9ee6bf743969f80c2a65..f1d0269b89776928b209bef823aa65c40c4f91ae 100644 (file)
@@ -1,6 +1,6 @@
 // btree version threads2i sched_yield version
 //     with reworked bt_deletekey code
-// 12 FEB 2014
+// 17 FEB 2014
 
 // author: karl malbrain, malbrain@cal.berkeley.edu
 
@@ -87,24 +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
@@ -151,7 +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 {
@@ -169,19 +162,15 @@ typedef struct BtPage_ {
        uint min;                                       // next key offset
        unsigned char bits:7;           // page size in bits
        unsigned char free:1;           // page is on free chain
-       unsigned char lvl:4;            // level of page
+       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 posted:1;         // page fence is posted
-       unsigned char goright:1;        // page is being deleted, go right
        unsigned char right[BtId];      // page number to right
-       unsigned char fence[256];       // page fence key
 } *BtPage;
 
 //     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
@@ -193,6 +182,8 @@ typedef struct {
 #endif
 } BtPool;
 
+#define CLOCK_bit 0x8000               // bit in pool->pin
+
 //  The loadpage interface object
 
 typedef struct {
@@ -266,15 +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_removepage (BtDb *bt, BtPageSet *set, uint lvl, unsigned char *pagefence);
-
 //     manager functions
 extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
 void bt_mgrclose (BtMgr *mgr);
@@ -304,7 +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
@@ -320,7 +309,7 @@ extern uint bt_tod (BtDb *bt, uint slot);
 
 //     Deleted keys are marked with a dead bit until
 //     page cleanup. The fence key for a node is
-//     present in a special array
+//     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
@@ -377,29 +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
@@ -411,31 +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
@@ -450,30 +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
@@ -481,9 +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
 }
 
@@ -492,9 +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
+       while( _InterlockedExchange8(latch->mutex, 1) )
+               SwitchToThread();
+#endif
+       latch->share--;
+#ifdef unix
+       *latch->mutex = 0;
 #else
-       _InterlockedExchangeAdd16 ((ushort *)latch, -Share);
+       _InterlockedExchange8(latch->mutex, 0);
 #endif
 }
 
@@ -703,14 +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
 }
@@ -720,10 +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);
@@ -882,12 +876,13 @@ SYSTEM_INFO sysinfo[1];
        latchmgr->alloc->bits = mgr->page_bits;
 
        for( lvl=MIN_lvl; lvl--; ) {
-               slotptr(latchmgr->alloc, 1)->off = offsetof(struct BtPage_, fence);
+               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
-               latchmgr->alloc->fence[0] = 2;                  // create stopper key
-               latchmgr->alloc->fence[1] = 0xff;
-               latchmgr->alloc->fence[2] = 0xff;
-               latchmgr->alloc->min = mgr->page_size;
+               key = keyptr(latchmgr->alloc, 1);
+               key->len = 2;           // create stopper key
+               key->key[0] = 0xff;
+               key->key[1] = 0xff;
+               latchmgr->alloc->min = mgr->page_size - 3;
                latchmgr->alloc->lvl = lvl;
                latchmgr->alloc->cnt = 1;
                latchmgr->alloc->act = 1;
@@ -1033,7 +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;
@@ -1044,32 +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)
@@ -1080,7 +1049,7 @@ int flag;
 
 #ifdef unix
        flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
-       pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED | MAP_POPULATE, bt->mgr->idx, off);
+       pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
        if( pool->map == MAP_FAILED )
                return bt->err = BTERR_map;
 
@@ -1125,42 +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;
        }
 
@@ -1180,13 +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;
        }
 
@@ -1205,20 +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;
                }
 
@@ -1227,14 +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
@@ -1252,13 +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;
        }
 }
@@ -1339,15 +1291,15 @@ 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
-               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
@@ -1373,44 +1325,38 @@ int reuse;
 int bt_findslot (BtPageSet *set, unsigned char *key, uint len)
 {
 uint diff, higher = set->page->cnt, low = 1, slot;
+uint good = 0;
 
        //        make stopper key an infinite fence value
 
        if( bt_getid (set->page->right) )
                higher++;
+       else
+               good++;
 
        //      low is the lowest candidate.
        //  loop ends when they meet
 
        //  higher is already
-       //      tested as .ge. the given key.
+       //      tested as .ge. the passed key.
 
        while( diff = higher - low ) {
                slot = low + ( diff >> 1 );
                if( keycmp (keyptr(set->page, slot), key, len) < 0 )
                        low = slot + 1;
                else
-                       higher = slot;
+                       higher = slot, good++;
        }
 
-       if( higher <= set->page->cnt )
-               return higher;
-
-       //      if leaf page, compare against fence value
-
        //      return zero if key is on right link page
-       //      or return slot beyond last key
-
-       if( set->page->lvl || keycmp ((BtKey)set->page->fence, key, len) < 0 )
-               return 0;
 
-       return higher;
+       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, BtPageSet *set, 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;
 uint drill = 0xff, slot;
@@ -1422,7 +1368,7 @@ BtPool *prevpool;
 
   do {
        // determine lock mode of drill level
-       mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead; 
+       mode = (drill == lvl) ? lock : BtLockRead; 
 
        set->latch = bt_pinlatch (bt, page_no);
        set->page_no = page_no;
@@ -1452,18 +1398,21 @@ BtPool *prevpool;
 
        bt_lockpage(mode, set->latch);
 
+       if( set->page->free )
+               return bt->err = BTERR_struct, 0;
+
        if( page_no > ROOT_page )
          bt_unlockpage(BtLockAccess, set->latch);
 
        // re-read and re-lock root after determining actual level of root
 
        if( set->page->lvl != drill) {
-               if ( set->page_no != ROOT_page )
+               if( set->page_no != ROOT_page )
                        return bt->err = BTERR_struct, 0;
                        
                drill = set->page->lvl;
 
-               if( lock == BtLockWrite && drill == lvl ) {
+               if( lock != BtLockRead && drill == lvl ) {
                  bt_unlockpage(mode, set->latch);
                  bt_unpinlatch (set->latch);
                  bt_unpinpool (set->pool);
@@ -1476,53 +1425,28 @@ BtPool *prevpool;
        prevpool = set->pool;
        prevmode = mode;
 
-       //      if page is being deleted and we should continue right
-
-       if( set->page->kill && set->page->goright ) {
-               page_no = bt_getid (set->page->right);
-               continue;
-       }
-
-       //      otherwise, wait for deleted node to clear
-
-       if( set->page->kill ) {
-               bt_unlockpage(mode, set->latch);
-               bt_unpinlatch (set->latch);
-               bt_unpinpool (set->pool);
-               page_no = ROOT_page;
-               prevpage = 0;
-               drill = 0xff;
-#ifdef unix
-               sched_yield();
-#else
-               SwitchToThread();
-#endif
-               continue;
-       }
-       
        //  find key on page at this level
        //  and descend to requested level
 
-       if( slot = bt_findslot (set, key, len) ) {
+       if( !set->page->kill )
+        if( slot = bt_findslot (set, key, len) ) {
          if( drill == lvl )
                return slot;
 
-         if( slot > set->page->cnt )
-               return bt->err = BTERR_struct;
-
          while( slotptr(set->page, slot)->dead )
                if( slot++ < set->page->cnt )
                        continue;
                else
-                       return bt->err = BTERR_struct, 0;
+                       goto slideright;
 
          page_no = bt_getid(slotptr(set->page, slot)->id);
          drill--;
          continue;
-       }
+        }
 
        //  or slide right into next page
 
+slideright:
        page_no = bt_getid(set->page->right);
 
   } while( page_no );
@@ -1533,61 +1457,6 @@ BtPool *prevpool;
   return 0;    // return error
 }
 
-// drill down fixing fence values for left sibling tree
-
-//  call with set write locked
-//     return with set unlocked & unpinned.
-
-BTERR bt_fixfences (BtDb *bt, BtPageSet *set, unsigned char *newfence)
-{
-unsigned char oldfence[256];
-BtPageSet next[1];
-int chk;
-
-  memcpy (oldfence, set->page->fence, 256);
-
-  while( !set->page->kill && set->page->lvl ) {
-       next->page_no = bt_getid(slotptr(set->page, set->page->cnt)->id);
-       next->latch = bt_pinlatch (bt, next->page_no);
-       bt_lockpage (BtLockParent, next->latch);
-       bt_lockpage (BtLockAccess, next->latch);
-       bt_lockpage (BtLockWrite, next->latch);
-       bt_unlockpage (BtLockAccess, next->latch);
-
-       if( next->pool = bt_pinpool (bt, next->page_no) )
-               next->page = bt_page (bt, next->pool, next->page_no);
-       else
-               return bt->err;
-
-       chk = keycmp ((BtKey)next->page->fence, oldfence + 1, *oldfence);
-
-       if( chk < 0 ) {
-         next->page_no = bt_getid (next->page->right);
-         bt_unlockpage (BtLockWrite, next->latch);
-         bt_unlockpage (BtLockParent, next->latch);
-         bt_unpinlatch (next->latch);
-         bt_unpinpool (next->pool);
-         continue;
-       }
-
-       if( chk > 0 )
-               return bt->err = BTERR_struct;
-
-       if( bt_fixfences (bt, next, newfence) )
-               return bt->err;
-
-       break;
-  }
-
-  memcpy (set->page->fence, newfence, 256);
-
-  bt_unlockpage (BtLockWrite, set->latch);
-  bt_unlockpage (BtLockParent, set->latch);
-  bt_unpinlatch (set->latch);
-  bt_unpinpool (set->pool);
-  return 0;
-}
-
 //     return page to free list
 //     page must be delete & write locked
 
@@ -1614,419 +1483,208 @@ void bt_freepage (BtDb *bt, BtPageSet *set)
        bt_spinreleasewrite (bt->mgr->latchmgr->lock);
 }
 
-//     remove the root level by promoting its only child
-//     call with parent and child pages
+//     a fence key was deleted from a page
+//     push new fence value upwards
 
-BTERR bt_removeroot (BtDb *bt, BtPageSet *root, BtPageSet *child)
+BTERR bt_fixfence (BtDb *bt, BtPageSet *set, uint lvl)
 {
-uid next = 0;
-
-  do {
-       if( next ) {
-         child->latch = bt_pinlatch (bt, next);
-         bt_lockpage (BtLockDelete, child->latch);
-         bt_lockpage (BtLockWrite, child->latch);
-
-         if( child->pool = bt_pinpool (bt, next) )
-               child->page = bt_page (bt, child->pool, next);
-         else
-               return bt->err;
-
-         child->page_no = next;
-       }
-
-       memcpy (root->page, child->page, bt->mgr->page_size);
-       next = bt_getid (slotptr(child->page, child->page->cnt)->id);
-       bt_freepage (bt, child);
-  } while( root->page->lvl > 1 && root->page->cnt == 1 );
-
-  bt_unlockpage (BtLockWrite, root->latch);
-  bt_unpinlatch (root->latch);
-  bt_unpinpool (root->pool);
-  return 0;
-}
+unsigned char leftkey[256], rightkey[256];
+uid page_no;
+BtKey ptr;
 
-//  pull right page over ourselves in simple merge
+       //      remove the old fence value
 
-BTERR bt_mergeright (BtDb *bt, BtPageSet *set, BtPageSet *parent, BtPageSet *right, uint slot, uint idx)
-{
-       //  install ourselves as child page
-       //      and delete ourselves from parent
+       ptr = keyptr(set->page, set->page->cnt);
+       memcpy (rightkey, ptr, ptr->len + 1);
 
-       bt_putid (slotptr(parent->page, idx)->id, set->page_no);
-       slotptr(parent->page, slot)->dead = 1;
-       parent->page->act--;
+       memset (slotptr(set->page, set->page->cnt--), 0, sizeof(BtSlot));
+       set->page->dirty = 1;
 
-       //      collapse any empty slots
+       ptr = keyptr(set->page, set->page->cnt);
+       memcpy (leftkey, ptr, ptr->len + 1);
+       page_no = set->page_no;
 
-       while( idx = parent->page->cnt - 1 )
-         if( slotptr(parent->page, idx)->dead ) {
-               *slotptr(parent->page, idx) = *slotptr(parent->page, idx + 1);
-               memset (slotptr(parent->page, parent->page->cnt--), 0, sizeof(BtSlot));
-         } else
-                 break;
+       bt_lockpage (BtLockParent, set->latch);
+       bt_unlockpage (BtLockWrite, set->latch);
 
-       memcpy (set->page, right->page, bt->mgr->page_size);
-       bt_unlockpage (BtLockParent, right->latch);
+       //      insert new (now smaller) fence key
 
-       bt_freepage (bt, right);
+       if( bt_insertkey (bt, leftkey+1, *leftkey, lvl+1, page_no, time(NULL)) )
+         return bt->err;
 
-       //      do we need to remove a btree level?
-       //      (leave the first page of leaves alone)
+       //      now delete old fence key
 
-       if( parent->page_no == ROOT_page && parent->page->cnt == 1 )
-         if( set->page->lvl )
-               return bt_removeroot (bt, parent, set);
+       if( bt_deletekey (bt, rightkey+1, *rightkey, lvl+1) )
+               return bt->err;
 
-       bt_unlockpage (BtLockWrite, parent->latch);
-       bt_unlockpage (BtLockDelete, set->latch);
-       bt_unlockpage (BtLockWrite, set->latch);
-       bt_unpinlatch (parent->latch);
-       bt_unpinpool (parent->pool);
-       bt_unpinlatch (set->latch);
+       bt_unlockpage (BtLockParent, set->latch);
+       bt_unpinlatch(set->latch);
        bt_unpinpool (set->pool);
        return 0;
 }
 
-//     remove both child and parent from the btree
-//     from the fence position in the parent
-//     call with both pages locked for writing
+//     root has a single child
+//     collapse a level from the tree
 
-BTERR bt_removeparent (BtDb *bt, BtPageSet *child, BtPageSet *parent, BtPageSet *right, BtPageSet *rparent, uint lvl)
+BTERR bt_collapseroot (BtDb *bt, BtPageSet *root)
 {
-unsigned char pagefence[256];
+BtPageSet child[1];
 uint idx;
 
-       //  pull right sibling over ourselves and unlock
-
-       memcpy (child->page, right->page, bt->mgr->page_size);
-
-       bt_unlockpage (BtLockWrite, child->latch);
-       bt_unpinlatch (child->latch);
-       bt_unpinpool (child->pool);
-
-       //  install ourselves into right link of old right page
-
-       bt_putid (right->page->right, child->page_no);
-       right->page->goright = 1;       // tell bt_loadpage to go right to us
-       right->page->kill = 1;
-
-       bt_unlockpage (BtLockWrite, right->latch);
-
-       //      remove our slot from our parent
-       //      signal to move right
+  // find the child entry and promote as new root contents
 
-       parent->page->goright = 1;      // tell bt_loadpage to go right to rparent
-       parent->page->kill = 1;
-       parent->page->act--;
-
-       //      redirect right page pointer in right parent to us
-
-       for( idx = 0; idx++ < rparent->page->cnt; )
-         if( !slotptr(rparent->page, idx)->dead )
+  do {
+       for( idx = 0; idx++ < root->page->cnt; )
+         if( !slotptr(root->page, idx)->dead )
                break;
 
-       if( bt_getid (slotptr(rparent->page, idx)->id) != right->page_no )
-               return bt->err = BTERR_struct;
-
-       bt_putid (slotptr(rparent->page, idx)->id, child->page_no);
-       bt_unlockpage (BtLockWrite, rparent->latch);
-       bt_unpinlatch (rparent->latch);
-       bt_unpinpool (rparent->pool);
+       child->page_no = bt_getid (slotptr(root->page, idx)->id);
 
-       //      free the right page
+       child->latch = bt_pinlatch (bt, child->page_no);
+       bt_lockpage (BtLockDelete, child->latch);
+       bt_lockpage (BtLockWrite, child->latch);
 
-       bt_lockpage (BtLockDelete, right->latch);
-       bt_lockpage (BtLockWrite, right->latch);
-       bt_freepage (bt, right);
+       if( child->pool = bt_pinpool (bt, child->page_no) )
+               child->page = bt_page (bt, child->pool, child->page_no);
+       else
+               return bt->err;
 
-       //      save parent page fence value
+       memcpy (root->page, child->page, bt->mgr->page_size);
+       bt_freepage (bt, child);
 
-       memcpy (pagefence, parent->page->fence, 256);
-       bt_unlockpage (BtLockWrite, parent->latch);
+  } while( root->page->lvl > 1 && root->page->act == 1 );
 
-       return bt_removepage (bt, parent, lvl, pagefence);
+  bt_unlockpage (BtLockWrite, root->latch);
+  bt_unpinlatch (root->latch);
+  bt_unpinpool (root->pool);
+  return 0;
 }
 
-//     remove page from btree
-//     call with page unlocked
-//     returns with page on free list
+//  find and delete key on page by marking delete flag bit
+//  if page becomes empty, delete it from the btree
 
-BTERR bt_removepage (BtDb *bt, BtPageSet *set, uint lvl, unsigned char *pagefence)
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
 {
-BtPageSet parent[1], sibling[1], rparent[1];
-unsigned char newfence[256];
-uint slot, idx;
+unsigned char lowerfence[256], higherfence[256];
+uint slot, idx, dirty = 0, fence, found;
+BtPageSet set[1], right[1];
 BtKey ptr;
 
-       //      load and lock our parent
-
-retry:
-       if( !(slot = bt_loadpage (bt, parent, pagefence+1, *pagefence, lvl+1, BtLockWrite)) )
+       if( slot = bt_loadpage (bt, set, key, len, lvl, BtLockWrite) )
+               ptr = keyptr(set->page, slot);
+       else
                return bt->err;
 
-       //      can we do a simple merge entirely
-       //      between siblings on the parent page?
-
-       if( slot < parent->page->cnt ) {
-               // find our right neighbor
-               //      right must exist because the stopper prevents
-               //      the rightmost page from deleting
-
-               for( idx = slot; idx++ < parent->page->cnt; )
-                 if( !slotptr(parent->page, idx)->dead )
-                       break;
-
-               sibling->page_no = bt_getid (slotptr (parent->page, idx)->id);
-
-               bt_lockpage (BtLockDelete, set->latch);
-               bt_lockpage (BtLockWrite, set->latch);
-
-               //      merge right if sibling shows up in
-               //  our parent and is not being killed
-
-               if( sibling->page_no == bt_getid (set->page->right) ) {
-                 sibling->latch = bt_pinlatch (bt, sibling->page_no);
-                 bt_lockpage (BtLockParent, sibling->latch);
-                 bt_lockpage (BtLockDelete, sibling->latch);
-                 bt_lockpage (BtLockWrite, sibling->latch);
-
-                 if( sibling->pool = bt_pinpool (bt, sibling->page_no) )
-                       sibling->page = bt_page (bt, sibling->pool, sibling->page_no);
-                 else
-                       return bt->err;
-
-                 if( !sibling->page->kill )
-                       return bt_mergeright(bt, set, parent, sibling, slot, idx);
-
-                 //  try again later
-
-                 bt_unlockpage (BtLockWrite, sibling->latch);
-                 bt_unlockpage (BtLockParent, sibling->latch);
-                 bt_unlockpage (BtLockDelete, sibling->latch);
-                 bt_unpinlatch (sibling->latch);
-                 bt_unpinpool (sibling->pool);
-               }
-
-               bt_unlockpage (BtLockDelete, set->latch);
-               bt_unlockpage (BtLockWrite, set->latch);
-               bt_unlockpage (BtLockWrite, parent->latch);
-               bt_unpinlatch (parent->latch);
-               bt_unpinpool (parent->pool);
-#ifdef linux
-               sched_yield();
-#else
-               SwitchToThread();
-#endif
-               goto retry;
-       }
-
-       //  find our left neighbor in our parent page
-
-       for( idx = slot; --idx; )
-         if( !slotptr(parent->page, idx)->dead )
-               break;
-
-       //      if no left neighbor, delete ourselves and our parent
-
-       if( !idx ) {
-               bt_lockpage (BtLockAccess, set->latch);
-               bt_lockpage (BtLockWrite, set->latch);
-               bt_unlockpage (BtLockAccess, set->latch);
-
-               rparent->page_no = bt_getid (parent->page->right);
-               rparent->latch = bt_pinlatch (bt, rparent->page_no);
-
-               bt_lockpage (BtLockAccess, rparent->latch);
-               bt_lockpage (BtLockWrite, rparent->latch);
-               bt_unlockpage (BtLockAccess, rparent->latch);
-
-               if( rparent->pool = bt_pinpool (bt, rparent->page_no) )
-                       rparent->page = bt_page (bt, rparent->pool, rparent->page_no);
-               else
-                       return bt->err;
+       //      are we deleting a fence slot?
 
-               if( !rparent->page->kill ) {
-                 sibling->page_no = bt_getid (set->page->right);
-                 sibling->latch = bt_pinlatch (bt, sibling->page_no);
+       fence = slot == set->page->cnt;
 
-                 bt_lockpage (BtLockAccess, sibling->latch);
-                 bt_lockpage (BtLockWrite, sibling->latch);
-                 bt_unlockpage (BtLockAccess, sibling->latch);
-
-                 if( sibling->pool = bt_pinpool (bt, sibling->page_no) )
-                       sibling->page = bt_page (bt, sibling->pool, sibling->page_no);
-                 else
-                       return bt->err;
-
-                 if( !sibling->page->kill )
-                       return bt_removeparent (bt, set, parent, sibling, rparent, lvl+1);
-
-                 //  try again later
+       // if key is found delete it, otherwise ignore request
 
-                 bt_unlockpage (BtLockWrite, sibling->latch);
-                 bt_unpinlatch (sibling->latch);
-                 bt_unpinpool (sibling->pool);
-               }
+       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--;
 
-               bt_unlockpage (BtLockWrite, set->latch);
-               bt_unlockpage (BtLockWrite, rparent->latch);
-               bt_unpinlatch (rparent->latch);
-               bt_unpinpool (rparent->pool);
+               // collapse empty slots
 
-               bt_unlockpage (BtLockWrite, parent->latch);
-               bt_unpinlatch (parent->latch);
-               bt_unpinpool (parent->pool);
-#ifdef linux
-               sched_yield();
-#else
-               SwitchToThread();
-#endif
-               goto retry;
-       }
-
-       // redirect parent to our left sibling
-       // lock and map our left sibling's page
+               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;
+                 }
 
-       sibling->page_no = bt_getid (slotptr(parent->page, idx)->id);
-       sibling->latch = bt_pinlatch (bt, sibling->page_no);
+       //      did we delete a fence key in an upper level?
 
-       //      wait our turn on fence key maintenance
+       if( dirty && lvl && set->page->act && fence )
+         if( bt_fixfence (bt, set, lvl) )
+               return bt->err;
+         else
+               return bt->found = found, 0;
 
-       bt_lockpage(BtLockParent, sibling->latch);
-       bt_lockpage(BtLockAccess, sibling->latch);
-       bt_lockpage(BtLockWrite, sibling->latch);
-       bt_unlockpage(BtLockAccess, sibling->latch);
+       //      is this a collapsed root?
 
-       if( sibling->pool = bt_pinpool (bt, sibling->page_no) )
-               sibling->page = bt_page (bt, sibling->pool, sibling->page_no);
-       else
+       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;
 
-       //  wait until left sibling is in our parent
+       //      return if page is not empty
 
-       if( bt_getid (sibling->page->right) != set->page_no ) {
-               bt_unlockpage (BtLockWrite, parent->latch);
-               bt_unlockpage (BtLockWrite, sibling->latch);
-               bt_unlockpage (BtLockParent, sibling->latch);
-               bt_unpinlatch (parent->latch);
-               bt_unpinpool (parent->pool);
-               bt_unpinlatch (sibling->latch);
-               bt_unpinpool (sibling->pool);
-#ifdef linux
-               sched_yield();
-#else
-               SwitchToThread();
-#endif
-               goto retry;
+       if( set->page->act ) {
+               bt_unlockpage(BtLockWrite, set->latch);
+               bt_unpinlatch (set->latch);
+               bt_unpinpool (set->pool);
+               return bt->found = found, 0;
        }
 
-       //      delete our left sibling from parent
-
-       slotptr(parent->page,idx)->dead = 1;
-       parent->page->dirty = 1;
-       parent->page->act--;
-
-       //      redirect our parent slot to our left sibling
-
-       bt_putid (slotptr(parent->page, slot)->id, sibling->page_no);
-       memcpy (sibling->page->right, set->page->right, BtId);
-
-       //      collapse dead slots from parent
-
-       while( idx = parent->page->cnt - 1 )
-         if( slotptr(parent->page, idx)->dead ) {
-               *slotptr(parent->page, idx) = *slotptr(parent->page, parent->page->cnt);
-               memset (slotptr(parent->page, parent->page->cnt--), 0, sizeof(BtSlot));
-         } else
-                 break;
-
-       //  free our original page
+       //      cache copy of fence key
+       //      to post in parent
 
-       bt_lockpage (BtLockDelete, set->latch);
-       bt_lockpage (BtLockWrite, set->latch);
-       bt_freepage (bt, set);
+       ptr = keyptr(set->page, set->page->cnt);
+       memcpy (lowerfence, ptr, ptr->len + 1);
 
-       //      go down the left node's fence keys to the leaf level
-       //      and update the fence keys in each page
+       //      obtain lock on right page
 
-       memcpy (newfence, parent->page->fence, 256);
-
-       if( bt_fixfences (bt, sibling, newfence) )
-               return bt->err;
+       right->page_no = bt_getid(set->page->right);
+       right->latch = bt_pinlatch (bt, right->page_no);
+       bt_lockpage (BtLockWrite, right->latch);
 
-       //  promote sibling as new root?
+       // pin page contents
 
-       if( parent->page_no == ROOT_page && parent->page->cnt == 1 )
-        if( sibling->page->lvl ) {
-         sibling->latch = bt_pinlatch (bt, sibling->page_no);
-         bt_lockpage (BtLockDelete, sibling->latch);
-         bt_lockpage (BtLockWrite, sibling->latch);
+       if( right->pool = bt_pinpool (bt, right->page_no) )
+               right->page = bt_page (bt, right->pool, right->page_no);
+       else
+               return 0;
 
-         if( sibling->pool = bt_pinpool (bt, sibling->page_no) )
-               sibling->page = bt_page (bt, sibling->pool, sibling->page_no);
-         else
-               return bt->err;
+       if( right->page->kill )
+               return bt->err = BTERR_struct;
 
-         return bt_removeroot (bt, parent, sibling);
-        }
+       // pull contents of right peer into our empty page
 
-       bt_unlockpage (BtLockWrite, parent->latch);
-       bt_unpinlatch (parent->latch);
-       bt_unpinpool (parent->pool);
+       memcpy (set->page, right->page, bt->mgr->page_size);
 
-       return 0;
-}
+       // cache copy of key to update
 
-//  find and delete key on page by marking delete flag bit
-//  if page becomes empty, delete it from the btree
+       ptr = keyptr(right->page, right->page->cnt);
+       memcpy (higherfence, ptr, ptr->len + 1);
 
-BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
-{
-unsigned char pagefence[256];
-uint slot, idx, found;
-BtPageSet set[1];
-BtKey ptr;
+       // mark right page deleted and point it to left page
+       //      until we can post parent updates
 
-       if( slot = bt_loadpage (bt, set, key, len, 0, BtLockWrite) )
-               ptr = keyptr(set->page, slot);
-       else
-               return bt->err;
+       bt_putid (right->page->right, set->page_no);
+       right->page->kill = 1;
 
-       // if key is found delete it, otherwise ignore request
+       bt_lockpage (BtLockParent, right->latch);
+       bt_unlockpage (BtLockWrite, right->latch);
 
-       if( found = slot <= set->page->cnt )
-         if( found = !keycmp (ptr, key, len) )
-               if( found = slotptr(set->page, slot)->dead == 0 ) {
-                 slotptr(set->page,slot)->dead = 1;
-                 set->page->dirty = 1;
-                 set->page->act--;
+       bt_lockpage (BtLockParent, set->latch);
+       bt_unlockpage (BtLockWrite, set->latch);
 
-                 // collapse empty slots
+       // redirect higher key directly to our new node contents
 
-                 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;
-               }
+       if( bt_insertkey (bt, higherfence+1, *higherfence, lvl+1, set->page_no, time(NULL)) )
+         return bt->err;
 
-       if( set->page->act ) {
-               bt_unlockpage(BtLockWrite, set->latch);
-               bt_unpinlatch (set->latch);
-               bt_unpinpool (set->pool);
-               return bt->found = found, 0;
-       }
+       //      delete old lower key to our node
 
-       memcpy (pagefence, set->page->fence, 256);
-       set->page->kill = 1;
+       if( bt_deletekey (bt, lowerfence+1, *lowerfence, lvl+1) )
+         return bt->err;
 
-       bt_unlockpage (BtLockWrite, set->latch);
+       //      obtain delete and write locks to right node
 
-       if( bt_removepage (bt, set, 0, pagefence) )
-               return bt->err;
+       bt_unlockpage (BtLockParent, right->latch);
+       bt_lockpage (BtLockDelete, right->latch);
+       bt_lockpage (BtLockWrite, right->latch);
+       bt_freepage (bt, right);
 
+       bt_unlockpage (BtLockParent, set->latch);
+       bt_unpinlatch (set->latch);
+       bt_unpinpool (set->pool);
        bt->found = found;
        return 0;
 }
@@ -2037,8 +1695,8 @@ 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, set, key, len, 0, BtLockRead) )
                ptr = keyptr(set->page, slot);
@@ -2048,10 +1706,9 @@ uid id;
        // if key exists, return row-id
        //      otherwise return 0
 
-       if( !keycmp (ptr, key, len) )
+       if( slot <= set->page->cnt )
+         if( !keycmp (ptr, key, len) )
                id = bt_getid(slotptr(set->page,slot)->id);
-       else
-               id = 0;
 
        bt_unlockpage (BtLockRead, set->latch);
        bt_unpinlatch (set->latch);
@@ -2066,7 +1723,7 @@ uid id;
 
 uint bt_cleanpage(BtDb *bt, BtPage page, uint amt, uint slot)
 {
-uint nxt = bt->mgr->page_size, off;
+uint nxt = bt->mgr->page_size;
 uint cnt = 0, idx = 0;
 uint max = page->cnt;
 uint newslot = max;
@@ -2094,26 +1751,22 @@ BtKey key;
        while( cnt++ < max ) {
                if( cnt == slot )
                        newslot = idx + 1;
-               if( slotptr(bt->frame,cnt)->dead )
+               if( cnt < max && slotptr(bt->frame,cnt)->dead )
                        continue;
 
-               // if its not the fence key,
                // copy the key across
 
-               off = slotptr(bt->frame,cnt)->off;
-
-               if( off >= sizeof(*page) ) {
-                       key = keyptr(bt->frame, cnt);
-                       off = nxt -= key->len + 1;
-                       memcpy ((unsigned char *)page + nxt, key, key->len + 1);
-               }
+               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++;
                slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
-               slotptr(page, idx)->off = off;
-               page->act++;
+               slotptr(page, idx)->off = nxt;
        }
 
        page->min = nxt;
@@ -2129,42 +1782,38 @@ BtKey key;
 
 // split the root and raise the height of the btree
 
-BTERR bt_splitroot(BtDb *bt, BtPageSet *root, uid page_no2)
+BTERR bt_splitroot(BtDb *bt, BtPageSet *root, unsigned char *leftkey, uid page_no2)
 {
 uint nxt = bt->mgr->page_size;
-unsigned char leftkey[256];
-uid new_page;
+uid left;
 
        //  Obtain an empty page to use, and copy the current
        //  root contents into it, e.g. lower keys
 
-       memcpy (leftkey, root->page->fence, 256);
-       root->page->posted = 1;
-
-       if( !(new_page = bt_newpage(bt, root->page)) )
+       if( !(left = bt_newpage(bt, root->page)) )
                return bt->err;
 
        // preserve the page info at the bottom
        // of higher keys and set rest to zero
 
        memset(root->page+1, 0, bt->mgr->page_size - sizeof(*root->page));
-       memset(root->page->fence, 0, 256);
-       root->page->fence[0] = 2;
-       root->page->fence[1] = 0xff;
-       root->page->fence[2] = 0xff;
 
-       // insert lower keys page fence key on newroot page
+       // insert lower keys page fence key on newroot page as first key
 
        nxt -= *leftkey + 1;
        memcpy ((unsigned char *)root->page + nxt, leftkey, *leftkey + 1);
-       bt_putid(slotptr(root->page, 1)->id, new_page);
+       bt_putid(slotptr(root->page, 1)->id, left);
        slotptr(root->page, 1)->off = nxt;
        
        // insert stopper key on newroot page
        // and increase the root height
 
+       nxt -= 3;
+       ((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 = offsetof(struct BtPage_, fence);
+       slotptr(root->page, 2)->off = nxt;
 
        bt_putid(root->page->right, 0);
        root->page->min = nxt;          // reset lowest used offset and key count
@@ -2185,10 +1834,11 @@ uid new_page;
 
 BTERR bt_splitpage (BtDb *bt, BtPageSet *set)
 {
-uint cnt = 0, idx = 0, max, nxt = bt->mgr->page_size, off;
-unsigned char fencekey[256];
+uint cnt = 0, idx = 0, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256], rightkey[256];
 uint lvl = set->page->lvl;
-uid right;
+BtPageSet right[1];
+uint prev;
 BtKey key;
 
        //  split higher half of keys to bt->frame
@@ -2199,23 +1849,21 @@ BtKey key;
        idx = 0;
 
        while( cnt++ < max ) {
-               if( !lvl || cnt < max ) {
-                       key = keyptr(set->page, cnt);
-                       off = nxt -= key->len + 1;
-                       memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
-               } else
-                       off = offsetof(struct BtPage_, fence);
+               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(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(set->page, cnt)->tod;
-               slotptr(bt->frame, idx)->off = off;
-               bt->frame->act++;
+               slotptr(bt->frame, idx)->off = nxt;
        }
 
-       if( set->page_no == ROOT_page )
-               bt->frame->posted = 1;
+       // remember existing fence key for new page to the right
+
+       memcpy (rightkey, key, key->len + 1);
 
-       memcpy (bt->frame->fence, set->page->fence, 256);
        bt->frame->bits = bt->mgr->page_bits;
        bt->frame->min = nxt;
        bt->frame->cnt = idx;
@@ -2228,7 +1876,7 @@ BtKey key;
 
        //      get new free page and write higher keys to it.
 
-       if( !(right = bt_newpage(bt, bt->frame)) )
+       if( !(right->page_no = bt_newpage(bt, bt->frame)) )
                return bt->err;
 
        //      update lower keys to continue in old page
@@ -2236,7 +1884,6 @@ BtKey key;
        memcpy (bt->frame, set->page, bt->mgr->page_size);
        memset (set->page+1, 0, bt->mgr->page_size - sizeof(*set->page));
        nxt = bt->mgr->page_size;
-       set->page->posted = 0;
        set->page->dirty = 0;
        set->page->act = 0;
        cnt = 0;
@@ -2246,79 +1893,56 @@ BtKey key;
 
        while( cnt++ < max / 2 ) {
                key = keyptr(bt->frame, cnt);
-
-               if( !lvl || cnt < max / 2 ) {
-                       off = nxt -= key->len + 1;
-                       memcpy ((unsigned char *)set->page + nxt, key, key->len + 1);
-               } else 
-                       off = offsetof(struct BtPage_, fence);
-
+               nxt -= key->len + 1;
+               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 = off;
+               slotptr(set->page, idx)->off = nxt;
                set->page->act++;
        }
 
-       // install fence key for smaller key page
+       // remember fence key for smaller page
 
-       memset(set->page->fence, 0, 256);
-       memcpy(set->page->fence, key, key->len + 1);
+       memcpy(fencekey, key, key->len + 1);
 
-       bt_putid(set->page->right, right);
+       bt_putid(set->page->right, right->page_no);
        set->page->min = nxt;
        set->page->cnt = idx;
 
        // if current page is the root page, split it
 
        if( set->page_no == ROOT_page )
-               return bt_splitroot (bt, set, right);
-
-       bt_unlockpage (BtLockWrite, set->latch);
+               return bt_splitroot (bt, set, fencekey, right->page_no);
 
        // insert new fences in their parent pages
 
-       while( 1 ) {
-               bt_lockpage (BtLockParent, set->latch);
-               bt_lockpage (BtLockWrite, set->latch);
-
-               memcpy (fencekey, set->page->fence, 256);
-               right = bt_getid (set->page->right);
-
-               if( set->page->posted ) {
-                       bt_unlockpage (BtLockParent, set->latch);
-                       bt_unlockpage (BtLockWrite, set->latch);
-                       bt_unpinlatch (set->latch);
-                       bt_unpinpool (set->pool);
-                       return 0;
-               }
+       right->latch = bt_pinlatch (bt, right->page_no);
+       bt_lockpage (BtLockParent, right->latch);
 
-               set->page->posted = 1;
-               bt_unlockpage (BtLockWrite, set->latch);
+       bt_lockpage (BtLockParent, set->latch);
+       bt_unlockpage (BtLockWrite, set->latch);
 
-               if( bt_insertkey (bt, fencekey+1, *fencekey, set->page_no, time(NULL), lvl+1) )
-                       return bt->err;
+       // insert new fence for reformulated left block of smaller keys
 
-               bt_unlockpage (BtLockParent, set->latch);
-               bt_unpinlatch (set->latch);
-               bt_unpinpool (set->pool);
+       if( bt_insertkey (bt, fencekey+1, *fencekey, lvl+1, set->page_no, time(NULL)) )
+               return bt->err;
 
-               if( !(set->page_no = right) )
-                       break;
+       // switch fence for right block of larger keys to new right page
 
-               set->latch = bt_pinlatch (bt, right);
+       if( bt_insertkey (bt, rightkey+1, *rightkey, lvl+1, right->page_no, time(NULL)) )
+               return bt->err;
 
-               if( set->pool = bt_pinpool (bt, right) )
-                       set->page = bt_page (bt, set->pool, right);
-               else
-                       return bt->err;
-       }
+       bt_unlockpage (BtLockParent, set->latch);
+       bt_unpinlatch (set->latch);
+       bt_unpinpool (set->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;
@@ -2329,15 +1953,14 @@ BtKey ptr;
                        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
 
-               if( slot <= set->page->cnt )
-                 if( !keycmp (ptr, key, len) ) {
+               if( !keycmp (ptr, key, len) ) {
                        if( slotptr(set->page, slot)->dead )
                                set->page->act++;
                        slotptr(set->page, slot)->dead = 0;
@@ -2364,14 +1987,14 @@ BtKey ptr;
        ((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++ )
+       for( idx = slot; idx < set->page->cnt; idx++ )
          if( slotptr(set->page, idx)->dead )
                break;
 
        // now insert key into array before slot
 
-       if( idx > set->page->cnt )
-               set->page->cnt++;
+       if( idx == set->page->cnt )
+               idx++, set->page->cnt++;
 
        set->page->act++;
 
@@ -2421,6 +2044,7 @@ uid right;
 
   do {
        right = bt_getid(bt->cursor->right);
+
        while( slot++ < bt->cursor->cnt )
          if( slotptr(bt->cursor,slot)->dead )
                continue;
@@ -2448,6 +2072,7 @@ uid right;
        bt_unpinlatch (set->latch);
        bt_unpinpool (set->pool);
        slot = 0;
+
   } while( 1 );
 
   return bt->err = 0;
@@ -2468,36 +2093,95 @@ 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;
+uid next, page_no;
 BtLatchSet *latch;
-BtPool *pool;
-BtPage page;
-uid page_no;
+BtKey ptr;
 
 #ifdef unix
-       for( idx = 1; idx < bt->mgr->latchmgr->latchdeployed; idx++ ) {
+       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( *(ushort *)latch->readwr ) {
-                       fprintf(stderr, "latchset %d r/w locked for page %.8x\n", idx, latch->page_no);
-                       *(ushort *)latch->readwr = 0;
-               }
-               if( *(ushort *)latch->access ) {
-                       fprintf(stderr, "latchset %d access locked for page %.8x\n", idx, latch->page_no);
-                       *(ushort *)latch->access = 0;
-               }
-               if( *(ushort *)latch->parent ) {
-                       fprintf(stderr, "latchset %d parent locked for page %.8x\n", idx, latch->page_no);
-                       *(ushort *)latch->parent = 0;
-               }
-               if( *(ushort *)latch->busy ) {
-                       fprintf(stderr, "latchset %d busy locked for page %.8x\n", idx, latch->page_no);
-                       *(ushort *)latch->parent = 0;
-               }
+               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;
@@ -2505,27 +2189,38 @@ uid page_no;
        }
 
        for( hashidx = 0; hashidx < bt->mgr->latchmgr->latchhash; hashidx++ ) {
+         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 {
                latch = bt->mgr->latchsets + idx;
-               if( latch->hash != hashidx ) {
+               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);
-                       latch->hash = hashidx;
-               }
+               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);
-
-               if( pool = bt_pinpool (bt, page_no) )
-                       page = bt_page (bt, pool, page_no);
-               else
-                       return;
-
-           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
 }
@@ -2582,7 +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;
                        }
@@ -2604,7 +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;
                        }
@@ -2668,21 +2363,31 @@ FILE *in;
 
        case 'c':
                fprintf(stderr, "started counting\n");
+               next = bt->mgr->latchmgr->nlatchpage + LATCH_page;
+               page_no = LEAF_page;
 
-               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);
-                       cnt += set->page->act;
-                       next = bt_getid (set->page->right);
-                       bt_unlockpage (BtLockRead, set->latch);
-                       bt_unpinlatch (set->latch);
-                       bt_unpinpool (set->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;
@@ -2702,16 +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;
@@ -2728,11 +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]);
@@ -2790,18 +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);
 }