// foster btree version g
-// 02 JAN 2014
+// 23 JAN 2014
// author: karl malbrain, malbrain@cal.berkeley.edu
#ifdef linux
#define _GNU_SOURCE
+#include <linux/futex.h>
+#define SYS_futex 202
#endif
#ifdef unix
#include <sys/mman.h>
#include <errno.h>
#include <pthread.h>
+#include <limits.h>
#else
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#define BT_ro 0x6f72 // ro
#define BT_rw 0x7772 // rw
+#define BT_latchtable 128 // number of latch manager slots
+
#define BT_maxbits 24 // maximum page size in bits
#define BT_minbits 9 // minimum page size in bits
#define BT_minpage (1 << BT_minbits) // minimum page size
unsigned char key[1];
} *BtKey;
-// mode & definition for spin latch implementation
-
-enum {
- Mutex = 1,
- Write = 2,
- Pending = 4,
- Share = 8
-} LockMode;
-
-// mutex locks the other fields
-// exclusive is set for write access
-// share is count of read accessors
-
-typedef struct {
- volatile ushort mutex:1;
- volatile ushort exclusive:1;
- volatile ushort pending:1;
- volatile ushort share:13;
-} BtSpinLatch;
-
// The first part of an index page.
// It is immediately followed
// by the BtSlot array of keys.
typedef struct Page {
- BtSpinLatch readwr[1]; // read/write lock
- BtSpinLatch access[1]; // access intent lock
- BtSpinLatch parent[1]; // parent SMO lock
- ushort foster; // count of foster children
- uint cnt; // count of keys in page
- uint act; // count of active keys
- uint min; // next key offset
+ volatile uint cnt; // count of keys in page
+ volatile uint act; // count of active keys
+ volatile uint min; // next key offset
+ volatile uint foster; // count of foster children
unsigned char bits; // page size in bits
- unsigned char lvl:6; // level of page
- unsigned char kill:1; // page is being deleted
+ unsigned char lvl:7; // level of page
unsigned char dirty:1; // page needs to be cleaned
unsigned char right[BtId]; // page number to right
} *BtPage;
+// mode & definition for latch implementation
+
+enum {
+ Mutex = 1 << 0, // the mutex bit
+ Write = 1 << 1, // the writers bit
+ Share = 1 << 2, // reader count
+ PendRd = 1 << 12, // reader contended count
+ PendWr = 1 << 22 // writer contended count
+} LockMode;
+
+enum {
+ QueRd = 1, // reader queue
+ QueWr = 2 // writer queue
+} RWQueue;
+
+// share is count of read accessors
+// grant write lock when share == 0
+
+typedef struct {
+ volatile uint mutex:1; // 1 = busy
+ volatile uint write:1; // 1 = exclusive
+ volatile uint share:10; // count of readers holding locks
+ volatile uint readwait:10; // count of readers waiting
+ volatile uint writewait:10; // count of writers waiting
+} BtLatch;
+
+// hash table entries
+
+typedef struct {
+ BtLatch latch[1];
+ volatile ushort slot; // Latch table entry at head of chain
+} BtHashEntry;
+
+// latch manager table structure
+
+typedef struct {
+ BtLatch readwr[1]; // read/write page lock
+ BtLatch access[1]; // Access Intent/Page delete
+ BtLatch parent[1]; // adoption of foster children
+ BtLatch 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
+ volatile ushort pin; // number of outstanding locks
+ volatile ushort hash; // hash slot entry is under
+ volatile uid page_no; // latch set page number
+} BtLatchSet;
+
// 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
- volatile ushort pin; // mapped page pin counter
+ ushort pin; // mapped page pin counter
ushort slot; // slot index in this array
void *hashprev; // previous pool entry for the same hash idx
void *hashnext; // next pool entry for the same hash idx
#endif
} BtPool;
+// structure for latch manager on ALLOC_page
+
+typedef struct {
+ struct Page alloc[2]; // next & free page_nos in right ptr
+ BtLatch lock[1]; // allocation area lite latch
+ ushort latchdeployed; // highest number of latch entries deployed
+ ushort nlatchpage; // number of latch pages at BT_latch
+ ushort latchtotal; // number of page latch entries
+ ushort latchhash; // number of latch hash table slots
+ ushort latchvictim; // next latch entry to examine
+ BtHashEntry table[0]; // the hash table
+} BtLatchMgr;
+
// The object structure for Btree access
typedef struct {
#else
HANDLE idx;
#endif
- volatile ushort poolcnt; // highest page pool node in use
- volatile ushort evicted; // last evicted hash table slot
+ ushort poolcnt; // highest page pool node in use
ushort poolmax; // highest page pool node allocated
- ushort poolmask; // total size of pages in mmap segment - 1
+ ushort poolmask; // total number of pages in mmap segment - 1
ushort hashsize; // size of Hash Table for pool entries
+ ushort evicted; // last evicted hash table slot
ushort *hash; // hash table of pool entries
BtPool *pool; // memory pool page segments
- BtSpinLatch *latch; // latches for pool hash slots
+ BtLatch *latch; // latches for pool hash slots
+ BtLatchMgr *latchmgr; // mapped latch page from allocation page
+ BtLatchSet *latchsets; // mapped latch set from latch pages
#ifndef unix
- HANDLE halloc, hlatch; // allocation and latch table handles
+ HANDLE halloc; // allocation and latch table handle
#endif
} BtMgr;
typedef struct {
BtMgr *mgr; // buffer manager for thread
- BtPage temp; // temporary frame buffer (memory mapped/file IO)
- BtPage alloc; // frame buffer for alloc page ( page 0 )
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 found; // last delete was found
int err; // last error
} BtDb;
// 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);
-extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+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 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);
extern uint bt_tod (BtDb *bt, uint slot);
// BTree page number constants
-#define ALLOC_page 0 // allocation of new pages
+#define ALLOC_page 0 // allocation & lock manager hash table
#define ROOT_page 1 // root of the btree
#define LEAF_page 2 // first page of leaves
+#define LATCH_page 3 // pages for lock manager
// Number of levels to create in a new BTree
return id;
}
+// Latch Manager
+
+int sys_futex(void *addr1, int op, int val1, struct timespec *timeout, void *addr2, int val3)
+{
+ return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
+}
+
// wait until write lock mode is clear
// and add 1 to the share count
-void bt_spinreadlock(BtSpinLatch *latch)
+void bt_spinreadlock(BtLatch *latch, int private)
{
-ushort prev;
+uint prev;
- do {
-#ifdef unix
- while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex )
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ while( 1 ) {
+ // obtain latch mutex
+ if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) {
sched_yield();
-#else
- while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex )
- SwitchToThread();
-#endif
- // see if exclusive request is granted or pending
+ continue;
+ }
- if( prev = !(latch->exclusive | latch->pending) )
-#ifdef unix
- __sync_fetch_and_add((ushort *)latch, Share);
-#else
- _InterlockedExchangeAdd16 ((ushort *)latch, Share);
-#endif
+ // wait for writers to clear
+ // increment read waiters and wait
-#ifdef unix
- __sync_fetch_and_and ((ushort *)latch, ~Mutex);
-#else
- _InterlockedAnd16((ushort *)latch, ~Mutex);
-#endif
+ if( latch->write || latch->writewait ) {
+ __sync_fetch_and_add ((uint *)latch, PendRd);
+ prev = __sync_fetch_and_and ((uint *)latch, ~Mutex) & ~Mutex;
+ sys_futex( (uint *)latch, FUTEX_WAIT_BITSET | private, prev, NULL, NULL, QueRd );
+ __sync_fetch_and_sub ((uint *)latch, PendRd);
+ continue;
+ }
+
+ // increment reader lock count
+ // and release latch mutex
- if( prev )
- return;
-#ifdef unix
- } while( sched_yield(), 1 );
-#else
- } while( SwitchToThread(), 1 );
-#endif
+ __sync_fetch_and_add ((uint *)latch, Share);
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+ return;
+ }
}
// wait for other read and write latches to relinquish
-void bt_spinwritelock(BtSpinLatch *latch)
+void bt_spinwritelock(BtLatch *latch, int private)
{
-ushort prev;
+uint prev;
- do {
-#ifdef unix
- while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ while( 1 ) {
+ // obtain latch mutex
+ if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) {
sched_yield();
-#else
- while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
- SwitchToThread();
-#endif
- if( prev = !(latch->share | latch->exclusive) )
+ continue;
+ }
+
+ // wait for write and reader count to clear
+
+ if( latch->write || latch->share ) {
+ __sync_fetch_and_add ((uint *)latch, PendWr);
+ prev = __sync_fetch_and_and ((uint *)latch, ~Mutex) & ~Mutex;
+ sys_futex( (uint *)latch, FUTEX_WAIT_BITSET | private, prev, NULL, NULL, QueWr );
+ __sync_fetch_and_sub ((uint *)latch, PendWr);
+ continue;
+ }
+
+ // take write mutex
+ // release latch mutex
+
+ __sync_fetch_and_or ((uint *)latch, Write);
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+ return;
+ }
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 otherwise
+
+int bt_spinwritetry(BtLatch *latch)
+{
+int ans;
+
+ // try for mutex,
+ // abandon request if not taken
+
+ if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex )
+ return 0;
+
+ // see if write mode is available
+
+ if( !latch->write && !latch->share ) {
+ __sync_fetch_and_or ((uint *)latch, Write);
+ ans = 1;
+ } else
+ ans = 0;
+
+ // release latch mutex
+
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+ return ans;
+}
+
+// clear write lock
+
+void bt_spinreleasewrite(BtLatch *latch, int private)
+{
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ // obtain latch mutex
+
+ while( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex )
+ sched_yield();
+
+ __sync_fetch_and_and ((uint *)latch, ~Write);
+
+ // favor writers
+
+ if( latch->writewait )
+ if( sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, 1, NULL, NULL, QueWr ) )
+ goto wakexit;
+
+ if( latch->readwait )
+ sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, INT_MAX, NULL, NULL, QueRd );
+
+ // release latch mutex
+
+wakexit:
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+}
+
+// decrement reader count
+
+void bt_spinreleaseread(BtLatch *latch, int private)
+{
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ // obtain latch mutex
+
+ while( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex )
+ sched_yield();
+
+ __sync_fetch_and_sub ((uint *)latch, Share);
+
+ // wake waiting writers
+
+ if( !latch->share && latch->writewait )
+ sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, 1, NULL, NULL, QueWr );
+
+ // release latch mutex
+
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+}
+
+// link latch table entry into latch hash table
+
+void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no)
+{
+BtLatchSet *set = bt->mgr->latchsets + victim;
+
+ if( set->next = bt->mgr->latchmgr->table[hashidx].slot )
+ bt->mgr->latchsets[set->next].prev = victim;
+
+ bt->mgr->latchmgr->table[hashidx].slot = victim;
+ set->page_no = page_no;
+ set->hash = hashidx;
+ set->prev = 0;
+}
+
+// release latch pin
+
+void bt_unpinlatch (BtLatchSet *set)
+{
#ifdef unix
- __sync_fetch_and_or((ushort *)latch, Write);
+ __sync_fetch_and_add(&set->pin, -1);
#else
- _InterlockedOr16((ushort *)latch, Write);
+ _InterlockedDecrement16 (&set->pin);
#endif
+}
+
+// find existing latchset or inspire new one
+// return with latchset pinned
+BtLatchSet *bt_pinlatch (BtDb *bt, uid page_no)
+{
+ushort hashidx = page_no % bt->mgr->latchmgr->latchhash;
+ushort slot, avail = 0, victim, idx;
+BtLatchSet *set;
+
+ // obtain read lock on hash table entry
+
+ bt_spinreadlock(bt->mgr->latchmgr->table[hashidx].latch, 0);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ } while( slot = set->next );
+
+ if( slot ) {
#ifdef unix
- __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
+ __sync_fetch_and_add(&set->pin, 1);
#else
- _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
+ _InterlockedIncrement16 (&set->pin);
#endif
+ }
- if( prev )
- return;
-#ifdef unix
- sched_yield();
-#else
- SwitchToThread();
-#endif
- } while( 1 );
-}
+ bt_spinreleaseread (bt->mgr->latchmgr->table[hashidx].latch, 0);
-// try to obtain write lock
+ if( slot )
+ return set;
-// return 1 if obtained,
-// 0 otherwise
+ // try again, this time with write lock
-int bt_spinwritetry(BtSpinLatch *latch)
-{
-ushort prev;
+ bt_spinwritelock(bt->mgr->latchmgr->table[hashidx].latch, 0);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ if( !set->pin && !avail )
+ avail = slot;
+ } while( slot = set->next );
+
+ // found our entry, or take over an unpinned one
+ if( slot || (slot = avail) ) {
+ set = bt->mgr->latchsets + slot;
#ifdef unix
- if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex )
- return 0;
+ __sync_fetch_and_add(&set->pin, 1);
#else
- if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex )
- return 0;
+ _InterlockedIncrement16 (&set->pin);
#endif
- // take write access if all bits are clear
+ set->page_no = page_no;
+ bt_spinreleasewrite(bt->mgr->latchmgr->table[hashidx].latch, 0);
+ return set;
+ }
- if( !prev )
+ // see if there are any unused entries
#ifdef unix
- __sync_fetch_and_or ((ushort *)latch, Write);
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, 1) + 1;
#else
- _InterlockedOr16((ushort *)latch, Write);
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchdeployed);
#endif
- return !prev;
-}
-// clear write mode
+ if( victim < bt->mgr->latchmgr->latchtotal ) {
+ set = bt->mgr->latchsets + victim;
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch, 0);
+ return set;
+ }
-void bt_spinreleasewrite(BtSpinLatch *latch)
-{
#ifdef unix
- __sync_fetch_and_and ((ushort *)latch, ~Write);
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, -1);
#else
- _InterlockedAnd16((ushort *)latch, ~Write);
+ victim = _InterlockedDecrement16 (&bt->mgr->latchmgr->latchdeployed);
#endif
-}
+ // find and reuse previous lock entry
-// decrement reader count
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->latchmgr->latchvictim, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchvictim) - 1;
+#endif
+ // we don't use slot zero
-void bt_spinreleaseread(BtSpinLatch *latch)
-{
+ if( victim %= bt->mgr->latchmgr->latchtotal )
+ set = bt->mgr->latchsets + victim;
+ else
+ continue;
+
+ // take control of our slot
+ // from other threads
+
+ if( set->pin || !bt_spinwritetry (set->busy) )
+ continue;
+
+ idx = set->hash;
+
+ // try to get write lock on hash chain
+ // skip entry if not obtained
+ // or has outstanding locks
+
+ if( !bt_spinwritetry (bt->mgr->latchmgr->table[idx].latch) ) {
+ bt_spinreleasewrite (set->busy, 0);
+ continue;
+ }
+
+ if( set->pin ) {
+ bt_spinreleasewrite (set->busy, 0);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch, 0);
+ continue;
+ }
+
+ // unlink our available victim from its hash chain
+
+ if( set->prev )
+ bt->mgr->latchsets[set->prev].next = set->next;
+ else
+ bt->mgr->latchmgr->table[idx].slot = set->next;
+
+ if( set->next )
+ bt->mgr->latchsets[set->next].prev = set->prev;
+
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch, 0);
#ifdef unix
- __sync_fetch_and_add((ushort *)latch, -Share);
+ __sync_fetch_and_add(&set->pin, 1);
#else
- _InterlockedExchangeAdd16 ((ushort *)latch, -Share);
+ _InterlockedIncrement16 (&set->pin);
#endif
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch, 0);
+ bt_spinreleasewrite (set->busy, 0);
+ return set;
+ }
}
void bt_mgrclose (BtMgr *mgr)
#endif
}
+#ifdef unix
+ munmap (mgr->latchsets, mgr->latchmgr->nlatchpage * mgr->page_size);
+ munmap (mgr->latchmgr, mgr->page_size);
+#else
+ FlushViewOfFile(mgr->latchmgr, 0);
+ UnmapViewOfFile(mgr->latchmgr);
+ CloseHandle(mgr->halloc);
+#endif
#ifdef unix
close (mgr->idx);
free (mgr->pool);
free (mgr->hash);
+ free (mgr->latch);
free (mgr->pooladvise);
free (mgr);
#else
CloseHandle(mgr->idx);
GlobalFree (mgr->pool);
GlobalFree (mgr->hash);
+ GlobalFree (mgr->latch);
GlobalFree (mgr);
#endif
}
BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, uint segsize, uint hashsize)
{
uint lvl, attr, cacheblk, last, slot, idx;
-BtPage alloc;
-int lockmode;
+uint nlatchpage, latchhash;
+BtLatchMgr *latchmgr;
off64_t size;
uint amt[1];
BtMgr* mgr;
BtKey key;
+int flag;
#ifndef unix
SYSTEM_INFO sysinfo[1];
#ifdef unix
mgr = calloc (1, sizeof(BtMgr));
- switch (mode & 0x7fff)
- {
- case BT_rw:
- mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
- lockmode = 1;
- break;
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
- case BT_ro:
- default:
- mgr->idx = open ((char*)name, O_RDONLY);
- lockmode = 0;
- break;
- }
if( mgr->idx == -1 )
return free(mgr), NULL;
#else
mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
attr = FILE_ATTRIBUTE_NORMAL;
- switch (mode & 0x7fff)
- {
- case BT_rw:
- mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
- lockmode = 1;
- break;
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
- case BT_ro:
- default:
- mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
- lockmode = 0;
- break;
- }
if( mgr->idx == INVALID_HANDLE_VALUE )
return GlobalFree(mgr), NULL;
#endif
#ifdef unix
- alloc = malloc (BT_maxpage);
+ latchmgr = malloc (BT_maxpage);
*amt = 0;
// read minimum page size to get root info
if( size = lseek (mgr->idx, 0L, 2) ) {
- if( pread(mgr->idx, alloc, BT_minpage, 0) == BT_minpage )
- bits = alloc->bits;
+ if( pread(mgr->idx, latchmgr, BT_minpage, 0) == BT_minpage )
+ bits = latchmgr->alloc->bits;
else
- return free(mgr), free(alloc), NULL;
+ return free(mgr), free(latchmgr), NULL;
} else if( mode == BT_ro )
- return bt_mgrclose (mgr), NULL;
+ return free(latchmgr), bt_mgrclose (mgr), NULL;
#else
- alloc = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
size = GetFileSize(mgr->idx, amt);
if( size || *amt ) {
- if( !ReadFile(mgr->idx, (char *)alloc, BT_minpage, amt, NULL) )
+ if( !ReadFile(mgr->idx, (char *)latchmgr, BT_minpage, amt, NULL) )
return bt_mgrclose (mgr), NULL;
- bits = alloc->bits;
+ bits = latchmgr->alloc->bits;
} else if( mode == BT_ro )
return bt_mgrclose (mgr), NULL;
#endif
#ifdef unix
mgr->pool = calloc (poolmax, sizeof(BtPool));
mgr->hash = calloc (hashsize, sizeof(ushort));
- mgr->latch = calloc (hashsize, sizeof(BtSpinLatch));
+ mgr->latch = calloc (hashsize, sizeof(BtLatch));
mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 8) / 8);
#else
- mgr->pool = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * (sizeof(BtPool)));
+ mgr->pool = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * sizeof(BtPool));
mgr->hash = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
- mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtSpinLatch));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtLatch));
#endif
+
if( size || *amt )
- goto mgrxit;
+ goto mgrlatch;
+
+ // initialize an empty b-tree with latch page, root page, page of leaves
+ // and page(s) of latches
- // initializes an empty b-tree with root page and page of leaves
+ memset (latchmgr, 0, 1 << bits);
+ nlatchpage = BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1;
+ bt_putid(latchmgr->alloc->right, MIN_lvl+1+nlatchpage);
+ latchmgr->alloc->bits = mgr->page_bits;
- memset (alloc, 0, 1 << bits);
- bt_putid(alloc->right, MIN_lvl+1);
- alloc->bits = mgr->page_bits;
+ latchmgr->nlatchpage = nlatchpage;
+ latchmgr->latchtotal = nlatchpage * (mgr->page_size / sizeof(BtLatchSet));
+
+ // initialize latch manager
+
+ latchhash = (mgr->page_size - sizeof(BtLatchMgr)) / sizeof(BtHashEntry);
+
+ // size of hash table = total number of latchsets
+
+ if( latchhash > latchmgr->latchtotal )
+ latchhash = latchmgr->latchtotal;
+
+ latchmgr->latchhash = latchhash;
#ifdef unix
- if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
return bt_mgrclose (mgr), NULL;
#else
- if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
return bt_mgrclose (mgr), NULL;
if( *amt < mgr->page_size )
return bt_mgrclose (mgr), NULL;
#endif
- memset (alloc, 0, 1 << bits);
- alloc->bits = mgr->page_bits;
+ memset (latchmgr, 0, 1 << bits);
+ latchmgr->alloc->bits = mgr->page_bits;
for( lvl=MIN_lvl; lvl--; ) {
- slotptr(alloc, 1)->off = mgr->page_size - 3;
- bt_putid(slotptr(alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
- key = keyptr(alloc, 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->key[0] = 0xff;
key->key[1] = 0xff;
- alloc->min = mgr->page_size - 3;
- alloc->lvl = lvl;
- alloc->cnt = 1;
- alloc->act = 1;
+ latchmgr->alloc->min = mgr->page_size - 3;
+ latchmgr->alloc->lvl = lvl;
+ latchmgr->alloc->cnt = 1;
+ latchmgr->alloc->act = 1;
#ifdef unix
- if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
return bt_mgrclose (mgr), NULL;
#else
- if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
return bt_mgrclose (mgr), NULL;
if( *amt < mgr->page_size )
#endif
}
- // create empty page area by writing last page of first
- // segment area (other pages are zeroed by O/S)
-
- if( mgr->poolmask ) {
- memset(alloc, 0, mgr->page_size);
- last = mgr->poolmask;
+ // clear out latch manager locks
+ // and rest of pages to round out segment
- while( last < MIN_lvl + 1 )
- last += mgr->poolmask + 1;
+ memset(latchmgr, 0, mgr->page_size);
+ last = MIN_lvl + 1;
+ while( last <= ((MIN_lvl + 1 + nlatchpage) | mgr->poolmask) ) {
#ifdef unix
- pwrite(mgr->idx, alloc, mgr->page_size, last << mgr->page_bits);
+ pwrite(mgr->idx, latchmgr, mgr->page_size, last << mgr->page_bits);
#else
SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
- if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
return bt_mgrclose (mgr), NULL;
if( *amt < mgr->page_size )
return bt_mgrclose (mgr), NULL;
#endif
+ last++;
}
-mgrxit:
+mgrlatch:
#ifdef unix
- free (alloc);
+ flag = PROT_READ | PROT_WRITE;
+ mgr->latchmgr = mmap (0, mgr->page_size, flag, MAP_SHARED, mgr->idx, ALLOC_page * mgr->page_size);
+ if( mgr->latchmgr == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+ mgr->latchsets = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
+ if( mgr->latchsets == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+#else
+ flag = PAGE_READWRITE;
+ mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL);
+ if( !mgr->halloc )
+ return bt_mgrclose (mgr), NULL;
+
+ flag = FILE_MAP_WRITE;
+ mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size);
+ if( !mgr->latchmgr )
+ return GetLastError(), bt_mgrclose (mgr), NULL;
+
+ mgr->latchsets = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
+#endif
+
+#ifdef unix
+ free (latchmgr);
#else
- VirtualFree (alloc, 0, MEM_RELEASE);
+ VirtualFree (latchmgr, 0, MEM_RELEASE);
#endif
return mgr;
}
bt->frame = (BtPage)bt->mem;
bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+
+ memset(bt->zero, 0, mgr->page_size);
return bt;
}
return bt->err = 0;
}
+// calculate page within pool
+
+BtPage bt_page (BtDb *bt, BtPool *pool, uid page_no)
+{
+uint subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+BtPage page;
+
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
+ }
+ }
+#endif
+ return page;
+}
+
+// release pool pin
+
+void bt_unpinpool (BtPool *pool)
+{
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+#else
+ _InterlockedDecrement16 (&pool->pin);
+#endif
+}
+
// find or place requested page in segment-pool
// return pool table entry, incrementing pin
-BtPool *bt_pinpage(BtDb *bt, uid page_no)
+BtPool *bt_pinpool(BtDb *bt, uid page_no)
{
BtPool *pool, *node, *next;
uint slot, idx, victim;
+BtLatchSet *set;
// lock hash table chain
idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
- bt_spinreadlock (&bt->mgr->latch[idx]);
+ bt_spinreadlock (&bt->mgr->latch[idx], 1);
// look up in hash table
#else
_InterlockedIncrement16 (&pool->pin);
#endif
- bt_spinreleaseread (&bt->mgr->latch[idx]);
+ bt_spinreleaseread (&bt->mgr->latch[idx], 1);
pool->lru++;
return pool;
}
// upgrade to write lock
- bt_spinreleaseread (&bt->mgr->latch[idx]);
- bt_spinwritelock (&bt->mgr->latch[idx]);
+ bt_spinreleaseread (&bt->mgr->latch[idx], 1);
+ bt_spinwritelock (&bt->mgr->latch[idx], 1);
// try to find page in pool with write lock
#else
_InterlockedIncrement16 (&pool->pin);
#endif
- bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ bt_spinreleasewrite (&bt->mgr->latch[idx], 1);
pool->lru++;
return pool;
}
#else
_InterlockedIncrement16 (&pool->pin);
#endif
- bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ bt_spinreleasewrite (&bt->mgr->latch[idx], 1);
return pool;
}
// skip this entry
if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
- bt_spinreleasewrite (&bt->mgr->latch[victim]);
+ bt_spinreleasewrite (&bt->mgr->latch[victim], 1);
continue;
}
if( node = pool->hashnext )
node->hashprev = pool->hashprev;
- bt_spinreleasewrite (&bt->mgr->latch[victim]);
+ bt_spinreleasewrite (&bt->mgr->latch[victim], 1);
// remove old file mapping
#ifdef unix
#else
_InterlockedIncrement16 (&pool->pin);
#endif
- bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ bt_spinreleasewrite (&bt->mgr->latch[idx], 1);
return pool;
}
}
// place write, read, or parent lock on requested page_no.
-// pin to buffer pool and return page pointer
+// pin to buffer pool and return latchset pointer
-BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr)
+void bt_lockpage(BtLock mode, BtLatchSet *set)
{
-BtPool *pool;
-uint subpage;
-BtPage page;
-
- // find/create maping in pool table
- // and pin our pool slot
-
- if( pool = bt_pinpage(bt, page_no) )
- subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
- else
- return bt->err;
-
- page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
-
-#ifdef unix
- {
- uint idx = subpage / 8;
- uint bit = subpage % 8;
-
- if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
- madvise (page, bt->mgr->page_size, MADV_WILLNEED);
- (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
- }
- }
-#endif
-
switch( mode ) {
case BtLockRead:
- bt_spinreadlock (page->readwr);
+ bt_spinreadlock (set->readwr, 0);
break;
case BtLockWrite:
- bt_spinwritelock (page->readwr);
+ bt_spinwritelock (set->readwr, 0);
break;
case BtLockAccess:
- bt_spinreadlock (page->access);
+ bt_spinreadlock (set->access, 0);
break;
case BtLockDelete:
- bt_spinwritelock (page->access);
+ bt_spinwritelock (set->access, 0);
break;
case BtLockParent:
- bt_spinwritelock (page->parent);
+ bt_spinwritelock (set->parent, 0);
break;
- default:
- return bt->err = BTERR_lock;
}
-
- if( pageptr )
- *pageptr = page;
-
- return bt->err = 0;
}
// remove write, read, or parent lock on requested page_no.
-BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+void bt_unlockpage(BtLock mode, BtLatchSet *set)
{
-BtPool *pool;
-uint subpage;
-BtPage page;
-uint idx;
-
- // since page is pinned
- // it should still be in the buffer pool
- // and is in no danger of being a victim for reuse
-
- idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
- bt_spinreadlock (&bt->mgr->latch[idx]);
-
- if( !(pool = bt_findpool(bt, page_no, idx)) )
- return bt->err = BTERR_hash;
-
- bt_spinreleaseread (&bt->mgr->latch[idx]);
-
- subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
- page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
-
switch( mode ) {
case BtLockRead:
- bt_spinreleaseread (page->readwr);
+ bt_spinreleaseread (set->readwr, 0);
break;
case BtLockWrite:
- bt_spinreleasewrite (page->readwr);
+ bt_spinreleasewrite (set->readwr, 0);
break;
case BtLockAccess:
- bt_spinreleaseread (page->access);
+ bt_spinreleaseread (set->access, 0);
break;
case BtLockDelete:
- bt_spinreleasewrite (page->access);
+ bt_spinreleasewrite (set->access, 0);
break;
case BtLockParent:
- bt_spinreleasewrite (page->parent);
+ bt_spinreleasewrite (set->parent, 0);
break;
- default:
- return bt->err = BTERR_lock;
}
-
-#ifdef unix
- __sync_fetch_and_add(&pool->pin, -1);
-#else
- _InterlockedDecrement16 (&pool->pin);
-#endif
- return bt->err = 0;
-}
-
-// deallocate a deleted page
-// place on free chain out of allocator page
-// fence key must already be removed from parent
-
-BTERR bt_freepage(BtDb *bt, uid page_no)
-{
- // obtain delete lock on deleted page
-
- if( bt_lockpage(bt, page_no, BtLockDelete, NULL) )
- return bt->err;
-
- // obtain write lock on deleted page
-
- if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) )
- return bt->err;
-
- // lock allocation page
-
- if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
- return bt->err;
-
- // store free chain in allocation page second right
- bt_putid(bt->temp->right, bt_getid(bt->alloc[1].right));
- bt_putid(bt->alloc[1].right, page_no);
-
- // unlock allocation page
-
- if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
- return bt->err;
-
- // remove write lock on deleted node
-
- if( bt_unlockpage(bt, page_no, BtLockWrite) )
- return bt->err;
-
- // remove delete lock on deleted node
-
- if( bt_unlockpage(bt, page_no, BtLockDelete) )
- return bt->err;
-
- return 0;
}
// allocate a new page and write page into it
uid bt_newpage(BtDb *bt, BtPage page)
{
+BtLatchSet *set;
+BtPool *pool;
uid new_page;
BtPage pmap;
-int subpage;
int reuse;
- // lock page zero
+ // lock allocation page
- if( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
- return 0;
+ bt_spinwritelock(bt->mgr->latchmgr->lock, 1);
// use empty chain first
// else allocate empty page
- if( new_page = bt_getid(bt->alloc[1].right) ) {
- if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) )
- return 0;
- bt_putid(bt->alloc[1].right, bt_getid(bt->temp->right));
- if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ 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);
+ else
return 0;
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(pmap->right));
+ bt_unpinpool (pool);
reuse = 1;
} else {
- new_page = bt_getid(bt->alloc->right);
- bt_putid(bt->alloc->right, new_page+1);
+ new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
+ bt_putid(bt->mgr->latchmgr->alloc->right, new_page+1);
reuse = 0;
}
-
#ifdef unix
- memset(bt->zero, 0, 3 * sizeof(BtSpinLatch)); // clear locks
- memcpy((char *)bt->zero + 3 * sizeof(BtSpinLatch), (char *)page + 3 * sizeof(BtSpinLatch), bt->mgr->page_size - 3 * sizeof(BtSpinLatch));
- if ( pwrite(bt->mgr->idx, bt->zero, 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 )
{
// 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 )
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( bt_lockpage(bt, new_page, BtLockWrite, &pmap) )
- return 0;
+ // unlock allocation latch
- // copy source page, but leave latch area intact
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock, 0);
- memcpy((char *)pmap + 3 * sizeof(BtSpinLatch), (char *)page + 3 * sizeof(BtSpinLatch), bt->mgr->page_size - 3 * sizeof(BtSpinLatch));
+ 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( bt_unlockpage (bt, new_page, BtLockWrite) )
- return 0;
-#endif
- // unlock allocation latch and return new page no
+#else
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock, 0);
- if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ // bring new page into pool and copy page.
+ // this will extend the file into the new pages.
+ // NB -- no latch required
+
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
return 0;
+ memcpy(pmap, page, bt->mgr->page_size);
+ bt_unpinpool (pool);
+#endif
return new_page;
}
// 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, unsigned char *key, uint len, uint lvl, BtLock lock)
{
uid page_no = ROOT_page, prevpage = 0;
+BtLatchSet *set, *prevset;
uint drill = 0xff, slot;
uint mode, prevmode;
+BtPool *prevpool;
// start at root of btree and drill down
// determine lock mode of drill level
mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+ // obtain latch set for this page
+
+ bt->set = bt_pinlatch (bt, page_no);
bt->page_no = page_no;
+ // pin page contents
+
+ if( bt->pool = bt_pinpool (bt, page_no) )
+ bt->page = bt_page (bt, bt->pool, page_no);
+ else
+ return 0;
+
// obtain access lock using lock chaining with Access mode
if( page_no > ROOT_page )
- if( bt_lockpage(bt, page_no, BtLockAccess, NULL) )
- return 0;
+ bt_lockpage(BtLockAccess, bt->set);
- // now unlock our (possibly foster) parent
+ // now unlock and unpin our (possibly foster) parent
- if( prevpage )
- if( bt_unlockpage(bt, prevpage, prevmode) )
- return 0;
- else
- prevpage = 0;
+ if( prevpage ) {
+ bt_unlockpage(prevmode, prevset);
+ bt_unpinlatch (prevset);
+ bt_unpinpool (prevpool);
+ prevpage = 0;
+ }
// obtain read lock using lock chaining
- // and pin page contents
- if( bt_lockpage(bt, page_no, mode, &bt->page) )
- return 0;
+ bt_lockpage(mode, bt->set);
if( page_no > ROOT_page )
- if( bt_unlockpage(bt, page_no, BtLockAccess) )
- return 0;
+ bt_unlockpage(BtLockAccess, bt->set);
// re-read and re-lock root after determining actual level of root
- if( bt->page_no == ROOT_page )
+ if( page_no == ROOT_page )
if( bt->page->lvl != drill) {
drill = bt->page->lvl;
- if( lock == BtLockWrite && drill == lvl )
- if( bt_unlockpage(bt, page_no, mode) )
- return 0;
- else
- continue;
+ if( lock == BtLockWrite && drill == lvl ) {
+ bt_unlockpage(mode, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ continue;
+ }
}
prevpage = bt->page_no;
+ prevpool = bt->pool;
+ prevset = bt->set;
prevmode = mode;
- // if page is being deleted,
- // move back to preceeding page
-
- if( bt->page->kill ) {
- page_no = bt_getid (bt->page->right);
- continue;
- }
-
// find key on page at this level
- // and descend to requested level
+ // and either descend to requested level
+ // or return key slot
slot = bt_findslot (bt, key, len);
- // is this slot a foster child?
+ // is this slot < foster child area
+ // on the requested level?
+
+ // if so, return actual slot even if dead
if( slot <= bt->page->cnt - bt->page->foster )
if( drill == lvl )
return slot;
+ // find next active slot
+
+ // note: foster children are never dead
+ // nor fence keys for interiour nodes
+
while( slotptr(bt->page, slot)->dead )
if( slot++ < bt->page->cnt )
continue;
else
- goto slideright;
+ return bt->err = BTERR_struct, 0; // last key shouldn't be deleted
+
+ // is this slot < foster child area
+ // if so, drill to next level
if( slot <= bt->page->cnt - bt->page->foster )
drill--;
- // continue down / right using overlapping locks
- // to protect pages being killed or split.
+ // continue right onto foster child
+ // or down to next level.
page_no = bt_getid(slotptr(bt->page, slot)->id);
- continue;
-
-slideright:
- page_no = bt_getid(bt->page->right);
} while( page_no );
}
// find and delete key on page by marking delete flag bit
-// when page becomes empty, delete it from the btree
+// when leaf page becomes empty, delete it from the btree
-BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
{
-unsigned char leftkey[256], rightkey[256];
+unsigned char leftkey[256];
+BtLatchSet *rset, *set;
+BtPool *pool, *rpool;
+BtPage rpage, page;
uid page_no, right;
uint slot, tod;
BtKey ptr;
- if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
ptr = keyptr(bt->page, slot);
else
return bt->err;
// if key is found delete it, otherwise ignore request
+ // note that fence keys of interiour nodes are not deleted.
- if( !keycmp (ptr, key, len) )
- if( slotptr(bt->page, slot)->dead == 0 ) {
+ if( bt->found = !keycmp (ptr, key, len) )
+ if( bt->found = slotptr(bt->page, slot)->dead == 0 ) {
slotptr(bt->page,slot)->dead = 1;
if( slot < bt->page->cnt )
bt->page->dirty = 1;
bt->page->act--;
}
- // return if page is not empty, or it has no right sibling
-
- right = bt_getid(bt->page->right);
page_no = bt->page_no;
+ pool = bt->pool;
+ page = bt->page;
+ set = bt->set;
- if( !right || bt->page->act )
- return bt_unlockpage(bt, page_no, BtLockWrite);
+ // return if page is not empty or not found
- // obtain Parent lock over write lock
-
- if( bt_lockpage(bt, page_no, BtLockParent, NULL) )
+ if( page->act || !bt->found ) {
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return bt->err;
+ }
- // cache copy of key to delete
+ // cache copy of fence key of empty node
- ptr = keyptr(bt->page, bt->page->cnt);
+ ptr = keyptr(page, page->cnt);
memcpy(leftkey, ptr, ptr->len + 1);
- // lock and map right page
+ // release write lock on empty node
+ // obtain Parent lock
- if( bt_lockpage(bt, right, BtLockWrite, &bt->temp) )
- return bt->err;
+ bt_unlockpage(BtLockWrite, set);
+ bt_lockpage(BtLockParent, set);
- // pull contents of next page into current empty page
- memcpy (bt->page, bt->temp, bt->mgr->page_size);
+ // load and lock parent to see
+ // if delete of empty node is OK
+ // ie, not a fence key of parent
- // cache copy of key to update
- ptr = keyptr(bt->temp, bt->temp->cnt);
- memcpy(rightkey, ptr, ptr->len + 1);
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, leftkey+1, *leftkey, 1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
- // Mark right page as deleted and point it to left page
- // until we can post updates at higher level.
+ // does parent level contain our fence key yet?
+ // and is it free of foster children?
- bt_putid(bt->temp->right, page_no);
- bt->temp->kill = 1;
- bt->temp->cnt = 0;
+ if( !bt->page->foster )
+ if( !keycmp (ptr, leftkey+1, *leftkey) )
+ break;
- if( bt_unlockpage(bt, right, BtLockWrite) )
- return bt->err;
- if( bt_unlockpage(bt, page_no, BtLockWrite) )
- return bt->err;
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ }
- // delete old lower key to consolidated node
+ // find our left fence key
- if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct; // last key shouldn't be deleted
+
+ // now we have both parent and child
+
+ bt_lockpage(BtLockDelete, set);
+ bt_lockpage(BtLockWrite, set);
+
+ // return if page has no right sibling within parent
+ // or if empty node is no longer empty
+
+ if( page->act || slot == bt->page->cnt ) {
+ // unpin parent
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ // unpin empty node
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return bt->err;
+ }
- // redirect higher key directly to consolidated node
+ // lock and map our right page
+ // note that it cannot be our foster child
+ // since the our node is empty
- if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
- ptr = keyptr(bt->page, slot);
+ right = bt_getid(page->right);
+
+ if( rpool = bt_pinpool (bt, right) )
+ rpage = bt_page (bt, rpool, right);
else
return bt->err;
- // since key already exists, update id
+ rset = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockWrite, rset);
+ bt_lockpage(BtLockDelete, rset);
+
+ // pull contents of right page into empty page
- if( keycmp (ptr, rightkey+1, *rightkey) )
- return bt->err = BTERR_struct;
+ memcpy (page, rpage, bt->mgr->page_size);
+
+ // delete left parent slot for old empty page
+ // and redirect right parent slot to it
+
+ bt->page->act--;
+ bt->page->dirty = 1;
+ slotptr(bt->page, slot)->dead = 1;
+
+ while( slot++ < bt->page->cnt )
+ if( !slotptr(bt->page, slot)->dead )
+ break;
- slotptr(bt->page, slot)->dead = 0;
bt_putid(slotptr(bt->page,slot)->id, page_no);
- if( bt_unlockpage(bt, bt->page_no, BtLockWrite) )
- return bt->err;
+ // release parent level lock
+ // and our empty node lock
- // obtain write lock and
- // add right block to free chain
+ bt_unlockpage(BtLockWrite, set);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
- if( bt_freepage (bt, right) )
- return bt->err;
+ // add killed right block to free chain
+ // lock latch mgr
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock, 0);
+
+ // store free chain in allocation page second right
+ bt_putid(rpage->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, right);
+
+ // unlock latch mgr and right page
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock, 0);
+
+ bt_unlockpage(BtLockWrite, rset);
+ bt_unlockpage(BtLockDelete, rset);
+ bt_unpinlatch (rset);
+ bt_unpinpool (rpool);
// remove ParentModify lock
- if( bt_unlockpage(bt, page_no, BtLockParent) )
- return bt->err;
-
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return 0;
-}
+}
// find key in leaf level and return row-id
// if key exists, return row-id
// otherwise return 0
- if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ if( slot <= bt->page->cnt && !keycmp (ptr, key, len) )
id = bt_getid(slotptr(bt->page,slot)->id);
else
id = 0;
- if( bt_unlockpage (bt, bt->page_no, BtLockRead) )
- return 0;
-
+ bt_unlockpage (BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
return id;
}
// check page for space available,
// clean if necessary and return
// 0 - page needs splitting
-// 1 - go ahead
+// >0 new slot value
-uint bt_cleanpage(BtDb *bt, uint amt)
+uint bt_cleanpage(BtDb *bt, uint amt, uint slot)
{
uint nxt = bt->mgr->page_size;
BtPage page = bt->page;
uint cnt = 0, idx = 0;
uint max = page->cnt;
+uint newslot;
BtKey key;
if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
- return 1;
+ return slot;
// skip cleanup if nothing to reclaim
// try cleaning up page first
+ // always leave fence key in the array
+ // otherwise, remove deleted key
+
+ // note: foster children are never dead
+ // nor are fence keys for interiour nodes
+
while( cnt++ < max ) {
- // always leave fence key and foster children in list
- if( cnt < max - page->foster && slotptr(bt->frame,cnt)->dead )
+ if( cnt == slot )
+ newslot = idx + 1;
+ else if( cnt < max && slotptr(bt->frame,cnt)->dead )
continue;
// copy key
+
key = keyptr(bt->frame, cnt);
nxt -= key->len + 1;
memcpy ((unsigned char *)page + nxt, key, key->len + 1);
// see if page has enough space now, or does it need splitting?
if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
- return 1;
+ return newslot;
return 0;
}
BtPage page = bt->page;
uint idx;
- // calculate next available slot and copy key into page
+ // find next available dead slot and copy key onto page
+ // note that foster children on the page are never dead
- page->min -= len + 1;
- ((unsigned char *)page)[page->min] = len;
- memcpy ((unsigned char *)page + page->min +1, key, len );
+ // look for next hole, but stay back from the fence key
for( idx = slot; idx < page->cnt; idx++ )
if( slotptr(page, idx)->dead )
break;
- // now insert key into array before slot
- // preserving the fence slot
-
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;
// contents into it from the root. Strip foster child key.
// (it's the stopper key)
+ memset (slotptr(root, root->cnt), 0, sizeof(BtSlot));
+ root->dirty = 1;
+ root->foster--;
root->act--;
root->cnt--;
- root->foster--;
// Save left fence key.
root->act = 2;
root->lvl++;
- // release root (bt->page)
+ // release and unpin root (bt->page)
- return bt_unlockpage(bt, ROOT_page, BtLockWrite);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
}
// split already locked full node
// in current page variables
-// return unlocked.
+// return unlocked and unpinned.
BTERR bt_splitpage (BtDb *bt)
{
uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
unsigned char fencekey[256];
uid page_no = bt->page_no;
+BtLatchSet *set = bt->set;
+BtPool *pool = bt->pool;
BtPage page = bt->page;
uint tod = time(NULL);
uint lvl = page->lvl;
uid new_page, right;
BtKey key;
- // initialize frame buffer
+ // initialize frame buffer for right node
memset (bt->frame, 0, bt->mgr->page_size);
max = page->cnt - page->foster;
idx = 0;
// split higher half of keys to bt->frame
- // leaving foster children in the left node.
+ // leaving old foster children in the left node,
+ // and adding a new foster child there.
while( cnt++ < max ) {
key = keyptr(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) )
+ bt->frame->act++;
slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
slotptr(bt->frame, idx)->off = nxt;
- bt->frame->act++;
}
- // transfer right link node
+ // transfer right link node to new right node
if( page_no > ROOT_page ) {
right = bt_getid (page->right);
bt->frame->cnt = idx;
bt->frame->lvl = lvl;
- // get new free page and write frame to it.
+ // get new free page and write right frame to it.
if( !(new_page = bt_newpage(bt, bt->frame)) )
return bt->err;
- // remember fence key for new page to add
- // as foster child
+ // remember fence key for new right page to add
+ // as foster child to the left node
key = keyptr(bt->frame, idx);
memcpy (fencekey, key, key->len + 1);
memcpy (bt->frame, page, bt->mgr->page_size);
memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
nxt = bt->mgr->page_size;
+ page->dirty = 0;
page->act = 0;
cnt = 0;
idx = 0;
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;
- page->act++;
}
- // insert new foster child at beginning of the current foster children
+ // insert new foster child for right page in queue
+ // before any of the current foster children
nxt -= *fencekey + 1;
memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+
bt_putid (slotptr(page,++idx)->id, new_page);
slotptr(page, idx)->tod = tod;
slotptr(page, idx)->off = nxt;
page->foster++;
page->act++;
- // continue with old foster child keys if any
+ // continue with old foster child keys
+ // note that none will be dead
cnt = bt->frame->cnt - bt->frame->foster;
// release wr lock on our page
- if( bt_unlockpage (bt, page_no, BtLockWrite) )
- return bt->err;
+ bt_unlockpage (BtLockWrite, set);
// obtain ParentModification lock for current page
- // to fix fence key and highest foster child on page
+ // to fix new fence key and oldest foster child on page
- if( bt_lockpage (bt, page_no, BtLockParent, NULL) )
- return bt->err;
+ bt_lockpage (BtLockParent, set);
- // get our highest foster child key to find in parent node
+ // get our new fence key to insert in parent node
- if( bt_lockpage (bt, page_no, BtLockRead, &page) )
- return bt->err;
+ bt_lockpage (BtLockRead, set);
- key = keyptr(page, page->cnt);
+ key = keyptr(page, page->cnt-1);
memcpy (fencekey, key, key->len+1);
- if( bt_unlockpage (bt, page_no, BtLockRead) )
- return bt->err;
-
- // update our parent
-try_again:
-
- do {
- slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
+ bt_unlockpage (BtLockRead, set);
- if( !slot )
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, page_no, tod, lvl + 1) )
return bt->err;
- // check if parent page has enough space for any possible key
-
- if( bt_cleanpage (bt, 256) )
- break;
+ // lock our page for writing
- if( bt_splitpage (bt) )
- return bt->err;
- } while( 1 );
+ bt_lockpage (BtLockRead, set);
- // see if we are still a foster child from another node
+ // switch old parent key from us to our oldest foster child
- if( bt_getid (slotptr(bt->page, slot)->id) != page_no ) {
- if( bt_unlockpage (bt, bt->page_no, BtLockWrite) )
- return bt->err;
-#ifdef unix
- sched_yield();
-#else
- SwitchToThread();
-#endif
- goto try_again;
- }
-
- // wait until readers from parent get their locks
- // on our page
-
- if( bt_lockpage (bt, page_no, BtLockDelete, NULL) )
- return bt->err;
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
- // lock our page for writing
+ new_page = bt_getid (slotptr(page, page->cnt)->id);
+ bt_unlockpage (BtLockRead, set);
- if( bt_lockpage (bt, page_no, BtLockWrite, &page) )
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, new_page, tod, lvl + 1) )
return bt->err;
- // switch parent fence key to foster child
-
- if( slotptr(page, page->cnt)->dead )
- slotptr(bt->page, slot)->dead = 1;
- else
- bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
-
- // remove highest foster child from our page
+ // now that it has its own parent pointer,
+ // remove oldest foster child from our page
+ bt_lockpage (BtLockWrite, set);
+ memset (slotptr(page, page->cnt), 0, sizeof(BtSlot));
+ page->dirty = 1;
+ page->foster--;
page->cnt--;
page->act--;
- page->foster--;
- page->dirty = 1;
- key = keyptr(page, page->cnt);
-
- // add our new fence key for foster child to our parent
- bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod);
-
- if( bt_unlockpage (bt, bt->page_no, BtLockWrite) )
- return bt->err;
+ // unlock and unpin
- if( bt_unlockpage (bt, page_no, BtLockDelete) )
- return bt->err;
-
- if( bt_unlockpage (bt, page_no, BtLockWrite) )
- return bt->err;
-
- return bt_unlockpage (bt, page_no, BtLockParent);
+ bt_unlockpage (BtLockWrite, set);
+ bt_unlockpage (BtLockParent, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return 0;
}
// Insert new key into the btree at leaf level.
-BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl)
{
uint slot, idx;
BtPage page;
BtKey ptr;
while( 1 ) {
- if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
ptr = keyptr(bt->page, slot);
else
{
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);
- return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return bt->err;
}
// check if page has enough space
- if( bt_cleanpage (bt, len) )
+ if( slot = bt_cleanpage (bt, len, slot) )
break;
if( bt_splitpage (bt) )
bt_addkeytopage (bt, slot, key, len, id, tod);
- return bt_unlockpage (bt, bt->page_no, BtLockWrite);
+ bt_unlockpage (BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
}
// cache page of keys into cursor and return starting slot for given key
// 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 ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
- return 0;
+ bt_unlockpage(BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
return slot;
}
uint bt_nextkey (BtDb *bt, uint slot)
{
+BtLatchSet *set;
+BtPool *pool;
BtPage page;
uid right;
break;
bt->cursor_page = right;
-
- if( bt_lockpage(bt, right, BtLockRead, &page) )
+ if( pool = bt_pinpool (bt, right) )
+ page = bt_page (bt, pool, right);
+ else
return 0;
- memcpy (bt->cursor, page, bt->mgr->page_size);
+ set = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockRead, set);
- if ( bt_unlockpage(bt, right, BtLockRead) )
- return 0;
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+ bt_unlockpage(BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
slot = 0;
} while( 1 );
#ifdef STANDALONE
+void bt_latchaudit (BtDb *bt)
+{
+ushort idx, hashidx;
+BtLatchSet *set;
+BtPool *pool;
+BtPage page;
+uid page_no;
+
+#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;
+ }
+ }
+
+ for( hashidx = 0; hashidx < bt->mgr->latchmgr->latchhash; hashidx++ ) {
+ if( *(uint *)bt->mgr->latchmgr->table[hashidx].latch )
+ fprintf(stderr, "latchmgr locked\n");
+ 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 )
+ fprintf(stderr, "latchset %d wrong hashidx\n", idx);
+ if( set->pin )
+ fprintf(stderr, "latchset %d pinned\n", idx);
+ } while( idx = set->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);
+ }
+#endif
+}
+
typedef struct {
char type, idx;
char *infile;
unsigned char key[256];
ThreadArg *args = arg;
int ch, len = 0, slot;
+BtLatchSet *set;
time_t tod[1];
+BtPool *pool;
BtPage page;
BtKey ptr;
BtDb *bt;
switch(args->type | 0x20)
{
+ case 'a':
+ fprintf(stderr, "started latch mgr audit\n");
+ bt_latchaudit (bt);
+ fprintf(stderr, "finished latch mgr audit\n");
+ break;
case 'w':
fprintf(stderr, "started indexing for %s\n", args->infile);
if( in = fopen (args->infile, "rb") )
else if( args->num )
sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
- if( bt_insertkey (bt, key, len, line, *tod) )
+ if( bt_insertkey (bt, key, len, line, *tod, 0) )
fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
len = 0;
}
else if( args->num )
sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
- if( bt_deletekey (bt, key, len, 0) )
+ if( bt_deletekey (bt, key, len) )
fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
len = 0;
}
fprintf(stderr, "started reading\n");
do {
- bt_lockpage (bt, page_no, BtLockRead, &page);
+ 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 (bt, page_no, BtLockRead);
+ bt_unlockpage (BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
} while( page_no = next );
cnt--; // remove stopper key
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