153 lines
3.9 KiB
C
153 lines
3.9 KiB
C
/*-
|
|
* See the file LICENSE for redistribution information.
|
|
*
|
|
* Copyright (c) 1996, 1997, 1998
|
|
* Sleepycat Software. All rights reserved.
|
|
*/
|
|
|
|
#include "config.h"
|
|
|
|
#ifndef lint
|
|
static const char sccsid[] = "@(#)lock_util.c 10.9 (Sleepycat) 4/26/98";
|
|
#endif /* not lint */
|
|
|
|
#ifndef NO_SYSTEM_INCLUDES
|
|
#include <sys/types.h>
|
|
|
|
#include <string.h>
|
|
#endif
|
|
|
|
#include "db_int.h"
|
|
#include "shqueue.h"
|
|
#include "db_page.h"
|
|
#include "db_shash.h"
|
|
#include "hash.h"
|
|
#include "lock.h"
|
|
|
|
/*
|
|
* __lock_cmp --
|
|
* This function is used to compare a DBT that is about to be entered
|
|
* into a hash table with an object already in the hash table. Note
|
|
* that it just returns true on equal and 0 on not-equal. Therefore
|
|
* this function cannot be used as a sort function; its purpose is to
|
|
* be used as a hash comparison function.
|
|
*
|
|
* PUBLIC: int __lock_cmp __P((const DBT *, DB_LOCKOBJ *));
|
|
*/
|
|
int
|
|
__lock_cmp(dbt, lock_obj)
|
|
const DBT *dbt;
|
|
DB_LOCKOBJ *lock_obj;
|
|
{
|
|
void *obj_data;
|
|
|
|
if (lock_obj->type != DB_LOCK_OBJTYPE)
|
|
return (0);
|
|
|
|
obj_data = SH_DBT_PTR(&lock_obj->lockobj);
|
|
return (dbt->size == lock_obj->lockobj.size &&
|
|
memcmp(dbt->data, obj_data, dbt->size) == 0);
|
|
}
|
|
|
|
/*
|
|
* PUBLIC: int __lock_locker_cmp __P((u_int32_t, DB_LOCKOBJ *));
|
|
*/
|
|
int
|
|
__lock_locker_cmp(locker, lock_obj)
|
|
u_int32_t locker;
|
|
DB_LOCKOBJ *lock_obj;
|
|
{
|
|
void *obj_data;
|
|
|
|
if (lock_obj->type != DB_LOCK_LOCKER)
|
|
return (0);
|
|
|
|
obj_data = SH_DBT_PTR(&lock_obj->lockobj);
|
|
return (memcmp(&locker, obj_data, sizeof(u_int32_t)) == 0);
|
|
}
|
|
|
|
/*
|
|
* The next two functions are the hash functions used to store objects in the
|
|
* lock hash table. They are hashing the same items, but one (__lock_ohash)
|
|
* takes a DBT (used for hashing a parameter passed from the user) and the
|
|
* other (__lock_lhash) takes a DB_LOCKOBJ (used for hashing something that is
|
|
* already in the lock manager). In both cases, we have a special check to
|
|
* fast path the case where we think we are doing a hash on a DB page/fileid
|
|
* pair. If the size is right, then we do the fast hash.
|
|
*
|
|
* We know that DB uses struct __db_ilocks for its lock objects. The first
|
|
* four bytes are the 4-byte page number and the next DB_FILE_ID_LEN bytes
|
|
* are a unique file id, where the first 4 bytes on UNIX systems are the file
|
|
* inode number, and the first 4 bytes on Windows systems are the FileIndexLow
|
|
* bytes. So, we use the XOR of the page number and the first four bytes of
|
|
* the file id to produce a 32-bit hash value.
|
|
*
|
|
* We have no particular reason to believe that this algorithm will produce
|
|
* a good hash, but we want a fast hash more than we want a good one, when
|
|
* we're coming through this code path.
|
|
*/
|
|
#define FAST_HASH(P) { \
|
|
u_int32_t __h; \
|
|
u_int8_t *__cp, *__hp; \
|
|
__hp = (u_int8_t *)&__h; \
|
|
__cp = (u_int8_t *)(P); \
|
|
__hp[0] = __cp[0] ^ __cp[4]; \
|
|
__hp[1] = __cp[1] ^ __cp[5]; \
|
|
__hp[2] = __cp[2] ^ __cp[6]; \
|
|
__hp[3] = __cp[3] ^ __cp[7]; \
|
|
return (__h); \
|
|
}
|
|
|
|
/*
|
|
* __lock_ohash --
|
|
*
|
|
* PUBLIC: u_int32_t __lock_ohash __P((const DBT *));
|
|
*/
|
|
u_int32_t
|
|
__lock_ohash(dbt)
|
|
const DBT *dbt;
|
|
{
|
|
if (dbt->size == sizeof(struct __db_ilock))
|
|
FAST_HASH(dbt->data);
|
|
|
|
return (__ham_func5(dbt->data, dbt->size));
|
|
}
|
|
|
|
/*
|
|
* __lock_lhash --
|
|
*
|
|
* PUBLIC: u_int32_t __lock_lhash __P((DB_LOCKOBJ *));
|
|
*/
|
|
u_int32_t
|
|
__lock_lhash(lock_obj)
|
|
DB_LOCKOBJ *lock_obj;
|
|
{
|
|
u_int32_t tmp;
|
|
void *obj_data;
|
|
|
|
obj_data = SH_DBT_PTR(&lock_obj->lockobj);
|
|
if (lock_obj->type == DB_LOCK_LOCKER) {
|
|
memcpy(&tmp, obj_data, sizeof(u_int32_t));
|
|
return (tmp);
|
|
}
|
|
|
|
if (lock_obj->lockobj.size == sizeof(struct __db_ilock))
|
|
FAST_HASH(obj_data);
|
|
|
|
return (__ham_func5(obj_data, lock_obj->lockobj.size));
|
|
}
|
|
|
|
/*
|
|
* __lock_locker_hash --
|
|
* Hash function for entering lockers into the hash table. Since these
|
|
* are simply 32-bit unsigned integers, just return the locker value.
|
|
*
|
|
* PUBLIC: u_int32_t __lock_locker_hash __P((u_int32_t));
|
|
*/
|
|
u_int32_t
|
|
__lock_locker_hash(locker)
|
|
u_int32_t locker;
|
|
{
|
|
return (locker);
|
|
}
|