1*0Sstevel@tonic-gate /*-
2*0Sstevel@tonic-gate * See the file LICENSE for redistribution information.
3*0Sstevel@tonic-gate *
4*0Sstevel@tonic-gate * Copyright (c) 1996, 1997, 1998
5*0Sstevel@tonic-gate * Sleepycat Software. All rights reserved.
6*0Sstevel@tonic-gate */
7*0Sstevel@tonic-gate
8*0Sstevel@tonic-gate #include "config.h"
9*0Sstevel@tonic-gate
10*0Sstevel@tonic-gate #ifndef lint
11*0Sstevel@tonic-gate static const char sccsid[] = "@(#)lock_util.c 10.10 (Sleepycat) 9/20/98";
12*0Sstevel@tonic-gate #endif /* not lint */
13*0Sstevel@tonic-gate
14*0Sstevel@tonic-gate #ifndef NO_SYSTEM_INCLUDES
15*0Sstevel@tonic-gate #include <sys/types.h>
16*0Sstevel@tonic-gate
17*0Sstevel@tonic-gate #include <string.h>
18*0Sstevel@tonic-gate #endif
19*0Sstevel@tonic-gate
20*0Sstevel@tonic-gate #include "db_int.h"
21*0Sstevel@tonic-gate #include "shqueue.h"
22*0Sstevel@tonic-gate #include "db_page.h"
23*0Sstevel@tonic-gate #include "db_shash.h"
24*0Sstevel@tonic-gate #include "hash.h"
25*0Sstevel@tonic-gate #include "lock.h"
26*0Sstevel@tonic-gate
27*0Sstevel@tonic-gate /*
28*0Sstevel@tonic-gate * __lock_cmp --
29*0Sstevel@tonic-gate * This function is used to compare a DBT that is about to be entered
30*0Sstevel@tonic-gate * into a hash table with an object already in the hash table. Note
31*0Sstevel@tonic-gate * that it just returns true on equal and 0 on not-equal. Therefore
32*0Sstevel@tonic-gate * this function cannot be used as a sort function; its purpose is to
33*0Sstevel@tonic-gate * be used as a hash comparison function.
34*0Sstevel@tonic-gate *
35*0Sstevel@tonic-gate * PUBLIC: int __lock_cmp __P((const DBT *, DB_LOCKOBJ *));
36*0Sstevel@tonic-gate */
37*0Sstevel@tonic-gate int
__lock_cmp(dbt,lock_obj)38*0Sstevel@tonic-gate __lock_cmp(dbt, lock_obj)
39*0Sstevel@tonic-gate const DBT *dbt;
40*0Sstevel@tonic-gate DB_LOCKOBJ *lock_obj;
41*0Sstevel@tonic-gate {
42*0Sstevel@tonic-gate void *obj_data;
43*0Sstevel@tonic-gate
44*0Sstevel@tonic-gate if (lock_obj->type != DB_LOCK_OBJTYPE)
45*0Sstevel@tonic-gate return (0);
46*0Sstevel@tonic-gate
47*0Sstevel@tonic-gate obj_data = SH_DBT_PTR(&lock_obj->lockobj);
48*0Sstevel@tonic-gate return (dbt->size == lock_obj->lockobj.size &&
49*0Sstevel@tonic-gate memcmp(dbt->data, obj_data, dbt->size) == 0);
50*0Sstevel@tonic-gate }
51*0Sstevel@tonic-gate
52*0Sstevel@tonic-gate /*
53*0Sstevel@tonic-gate * PUBLIC: int __lock_locker_cmp __P((u_int32_t, DB_LOCKOBJ *));
54*0Sstevel@tonic-gate */
55*0Sstevel@tonic-gate int
__lock_locker_cmp(locker,lock_obj)56*0Sstevel@tonic-gate __lock_locker_cmp(locker, lock_obj)
57*0Sstevel@tonic-gate u_int32_t locker;
58*0Sstevel@tonic-gate DB_LOCKOBJ *lock_obj;
59*0Sstevel@tonic-gate {
60*0Sstevel@tonic-gate void *obj_data;
61*0Sstevel@tonic-gate
62*0Sstevel@tonic-gate if (lock_obj->type != DB_LOCK_LOCKER)
63*0Sstevel@tonic-gate return (0);
64*0Sstevel@tonic-gate
65*0Sstevel@tonic-gate obj_data = SH_DBT_PTR(&lock_obj->lockobj);
66*0Sstevel@tonic-gate return (memcmp(&locker, obj_data, sizeof(u_int32_t)) == 0);
67*0Sstevel@tonic-gate }
68*0Sstevel@tonic-gate
69*0Sstevel@tonic-gate /*
70*0Sstevel@tonic-gate * The next two functions are the hash functions used to store objects in the
71*0Sstevel@tonic-gate * lock hash table. They are hashing the same items, but one (__lock_ohash)
72*0Sstevel@tonic-gate * takes a DBT (used for hashing a parameter passed from the user) and the
73*0Sstevel@tonic-gate * other (__lock_lhash) takes a DB_LOCKOBJ (used for hashing something that is
74*0Sstevel@tonic-gate * already in the lock manager). In both cases, we have a special check to
75*0Sstevel@tonic-gate * fast path the case where we think we are doing a hash on a DB page/fileid
76*0Sstevel@tonic-gate * pair. If the size is right, then we do the fast hash.
77*0Sstevel@tonic-gate *
78*0Sstevel@tonic-gate * We know that DB uses DB_LOCK_ILOCK types for its lock objects. The first
79*0Sstevel@tonic-gate * four bytes are the 4-byte page number and the next DB_FILE_ID_LEN bytes
80*0Sstevel@tonic-gate * are a unique file id, where the first 4 bytes on UNIX systems are the file
81*0Sstevel@tonic-gate * inode number, and the first 4 bytes on Windows systems are the FileIndexLow
82*0Sstevel@tonic-gate * bytes. So, we use the XOR of the page number and the first four bytes of
83*0Sstevel@tonic-gate * the file id to produce a 32-bit hash value.
84*0Sstevel@tonic-gate *
85*0Sstevel@tonic-gate * We have no particular reason to believe that this algorithm will produce
86*0Sstevel@tonic-gate * a good hash, but we want a fast hash more than we want a good one, when
87*0Sstevel@tonic-gate * we're coming through this code path.
88*0Sstevel@tonic-gate */
89*0Sstevel@tonic-gate #define FAST_HASH(P) { \
90*0Sstevel@tonic-gate u_int32_t __h; \
91*0Sstevel@tonic-gate u_int8_t *__cp, *__hp; \
92*0Sstevel@tonic-gate __hp = (u_int8_t *)&__h; \
93*0Sstevel@tonic-gate __cp = (u_int8_t *)(P); \
94*0Sstevel@tonic-gate __hp[0] = __cp[0] ^ __cp[4]; \
95*0Sstevel@tonic-gate __hp[1] = __cp[1] ^ __cp[5]; \
96*0Sstevel@tonic-gate __hp[2] = __cp[2] ^ __cp[6]; \
97*0Sstevel@tonic-gate __hp[3] = __cp[3] ^ __cp[7]; \
98*0Sstevel@tonic-gate return (__h); \
99*0Sstevel@tonic-gate }
100*0Sstevel@tonic-gate
101*0Sstevel@tonic-gate /*
102*0Sstevel@tonic-gate * __lock_ohash --
103*0Sstevel@tonic-gate *
104*0Sstevel@tonic-gate * PUBLIC: u_int32_t __lock_ohash __P((const DBT *));
105*0Sstevel@tonic-gate */
106*0Sstevel@tonic-gate u_int32_t
__lock_ohash(dbt)107*0Sstevel@tonic-gate __lock_ohash(dbt)
108*0Sstevel@tonic-gate const DBT *dbt;
109*0Sstevel@tonic-gate {
110*0Sstevel@tonic-gate if (dbt->size == sizeof(DB_LOCK_ILOCK))
111*0Sstevel@tonic-gate FAST_HASH(dbt->data);
112*0Sstevel@tonic-gate
113*0Sstevel@tonic-gate return (__ham_func5(dbt->data, dbt->size));
114*0Sstevel@tonic-gate }
115*0Sstevel@tonic-gate
116*0Sstevel@tonic-gate /*
117*0Sstevel@tonic-gate * __lock_lhash --
118*0Sstevel@tonic-gate *
119*0Sstevel@tonic-gate * PUBLIC: u_int32_t __lock_lhash __P((DB_LOCKOBJ *));
120*0Sstevel@tonic-gate */
121*0Sstevel@tonic-gate u_int32_t
__lock_lhash(lock_obj)122*0Sstevel@tonic-gate __lock_lhash(lock_obj)
123*0Sstevel@tonic-gate DB_LOCKOBJ *lock_obj;
124*0Sstevel@tonic-gate {
125*0Sstevel@tonic-gate u_int32_t tmp;
126*0Sstevel@tonic-gate void *obj_data;
127*0Sstevel@tonic-gate
128*0Sstevel@tonic-gate obj_data = SH_DBT_PTR(&lock_obj->lockobj);
129*0Sstevel@tonic-gate if (lock_obj->type == DB_LOCK_LOCKER) {
130*0Sstevel@tonic-gate memcpy(&tmp, obj_data, sizeof(u_int32_t));
131*0Sstevel@tonic-gate return (tmp);
132*0Sstevel@tonic-gate }
133*0Sstevel@tonic-gate
134*0Sstevel@tonic-gate if (lock_obj->lockobj.size == sizeof(DB_LOCK_ILOCK))
135*0Sstevel@tonic-gate FAST_HASH(obj_data);
136*0Sstevel@tonic-gate
137*0Sstevel@tonic-gate return (__ham_func5(obj_data, lock_obj->lockobj.size));
138*0Sstevel@tonic-gate }
139*0Sstevel@tonic-gate
140*0Sstevel@tonic-gate /*
141*0Sstevel@tonic-gate * __lock_locker_hash --
142*0Sstevel@tonic-gate * Hash function for entering lockers into the hash table. Since these
143*0Sstevel@tonic-gate * are simply 32-bit unsigned integers, just return the locker value.
144*0Sstevel@tonic-gate *
145*0Sstevel@tonic-gate * PUBLIC: u_int32_t __lock_locker_hash __P((u_int32_t));
146*0Sstevel@tonic-gate */
147*0Sstevel@tonic-gate u_int32_t
__lock_locker_hash(locker)148*0Sstevel@tonic-gate __lock_locker_hash(locker)
149*0Sstevel@tonic-gate u_int32_t locker;
150*0Sstevel@tonic-gate {
151*0Sstevel@tonic-gate return (locker);
152*0Sstevel@tonic-gate }
153