about summary refs log tree commit diff
path: root/db2/db/db_dispatch.c
blob: 616d08c3fff207f5ad0046f848a6ab9af42cb19a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *	Sleepycat Software.  All rights reserved.
 */
/*
 * Copyright (c) 1995, 1996
 *	The President and Fellows of Harvard University.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Margo Seltzer.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)db_dispatch.c	10.20 (Sleepycat) 10/10/98";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <errno.h>
#include <shqueue.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#endif

#include "db_int.h"
#include "db_page.h"
#include "db_dispatch.h"
#include "db_am.h"
#include "common_ext.h"
#include "log_auto.h"
#include "txn.h"
#include "txn_auto.h"

/*
 * Data structures to manage the DB dispatch table.  The dispatch table
 * is a dynamically allocated array of pointers to dispatch functions.
 * The dispatch_size is the number of entries possible in the current
 * dispatch table and the dispatch_valid is the number of valid entries
 * in the dispatch table.
 */
static int (**dispatch_table) __P((DB_LOG *, DBT *, DB_LSN *, int, void *));
static u_int32_t dispatch_size = 0;

/*
 * __db_dispatch --
 *
 * This is the transaction dispatch function used by the db access methods.
 * It is designed to handle the record format used by all the access
 * methods (the one automatically generated by the db_{h,log,read}.sh
 * scripts in the tools directory).  An application using a different
 * recovery paradigm will supply a different dispatch function to txn_open.
 *
 * PUBLIC: int __db_dispatch __P((DB_LOG *, DBT *, DB_LSN *, int, void *));
 */
int
__db_dispatch(logp, db, lsnp, redo, info)
	DB_LOG *logp;		/* The log file. */
	DBT *db;		/* The log record upon which to dispatch. */
	DB_LSN *lsnp;		/* The lsn of the record being dispatched. */
	int redo;		/* Redo this op (or undo it). */
	void *info;
{
	u_int32_t rectype, txnid;

	memcpy(&rectype, db->data, sizeof(rectype));
	memcpy(&txnid, (u_int8_t *)db->data + sizeof(rectype), sizeof(txnid));

	switch (redo) {
	case TXN_REDO:
	case TXN_UNDO:
		return ((dispatch_table[rectype])(logp, db, lsnp, redo, info));
	case TXN_OPENFILES:
		if (rectype < DB_txn_BEGIN )
			return ((dispatch_table[rectype])(logp,
			    db, lsnp, redo, info));
		break;
	case TXN_BACKWARD_ROLL:
		/*
		 * Running full recovery in the backward pass.  If we've
		 * seen this txnid before and added to it our commit list,
		 * then we do nothing during this pass.  If we've never
		 * seen it, then we call the appropriate recovery routine
		 * in "abort mode".
		 */
		if (rectype == DB_log_register || rectype == DB_txn_ckp ||
		    __db_txnlist_find(info, txnid) == DB_NOTFOUND)
			return ((dispatch_table[rectype])(logp,
			    db, lsnp, TXN_UNDO, info));
		break;
	case TXN_FORWARD_ROLL:
		/*
		 * In the forward pass, if we haven't seen the transaction,
		 * do nothing, else recovery it.
		 */
		if (rectype == DB_log_register || rectype == DB_txn_ckp ||
		    __db_txnlist_find(info, txnid) != DB_NOTFOUND)
			return ((dispatch_table[rectype])(logp,
			    db, lsnp, TXN_REDO, info));
		break;
	default:
		abort();
	}
	return (0);
}

/*
 * __db_add_recovery --
 *
 * PUBLIC: int __db_add_recovery __P((DB_ENV *,
 * PUBLIC:    int (*)(DB_LOG *, DBT *, DB_LSN *, int, void *), u_int32_t));
 */
int
__db_add_recovery(dbenv, func, ndx)
	DB_ENV *dbenv;
	int (*func) __P((DB_LOG *, DBT *, DB_LSN *, int, void *));
	u_int32_t ndx;
{
	u_int32_t i;
	int ret;

	COMPQUIET(dbenv, NULL);		/* !!!: not currently used. */

	/* Check if we have to grow the table. */
	if (ndx >= dispatch_size) {
		if ((ret = __os_realloc(&dispatch_table,
		    (DB_user_BEGIN + dispatch_size) *
		    sizeof(dispatch_table[0]))) != 0)
			return (ret);
		for (i = dispatch_size,
		    dispatch_size += DB_user_BEGIN; i < dispatch_size; ++i)
			dispatch_table[i] = NULL;
	}

	dispatch_table[ndx] = func;
	return (0);
}

/*
 * __db_txnlist_init --
 *	Initialize transaction linked list.
 *
 * PUBLIC: int __db_txnlist_init __P((void *));
 */
int
__db_txnlist_init(retp)
	void *retp;
{
	DB_TXNHEAD *headp;
	int ret;

	if ((ret = __os_malloc(sizeof(DB_TXNHEAD), NULL, &headp)) != 0)
		return (ret);

	LIST_INIT(&headp->head);
	headp->maxid = 0;
	headp->generation = 1;

	*(void **)retp = headp;
	return (0);
}

/*
 * __db_txnlist_add --
 *	Add an element to our transaction linked list.
 *
 * PUBLIC: int __db_txnlist_add __P((void *, u_int32_t));
 */
int
__db_txnlist_add(listp, txnid)
	void *listp;
	u_int32_t txnid;
{
	DB_TXNHEAD *hp;
	DB_TXNLIST *elp;
	int ret;

	if ((ret = __os_malloc(sizeof(DB_TXNLIST), NULL, &elp)) != 0)
		return (ret);

	elp->txnid = txnid;
	hp = (DB_TXNHEAD *)listp;
	LIST_INSERT_HEAD(&hp->head, elp, links);
	if (txnid > hp->maxid)
		hp->maxid = txnid;
	elp->generation = hp->generation;

	return (0);
}

/*
 * __db_txnlist_find --
 *	Checks to see if a txnid with the current generation is in the
 *	txnid list.
 *
 * PUBLIC: int __db_txnlist_find __P((void *, u_int32_t));
 */
int
__db_txnlist_find(listp, txnid)
	void *listp;
	u_int32_t txnid;
{
	DB_TXNHEAD *hp;
	DB_TXNLIST *p;

	if ((hp = (DB_TXNHEAD *)listp) == NULL)
		return (DB_NOTFOUND);

	for (p = hp->head.lh_first; p != NULL; p = p->links.le_next)
		if (p->txnid == txnid && hp->generation == p->generation)
			return (0);

	return (DB_NOTFOUND);
}

/*
 * __db_txnlist_end --
 *	Discard transaction linked list.
 *
 * PUBLIC: void __db_txnlist_end __P((void *));
 */
void
__db_txnlist_end(listp)
	void *listp;
{
	DB_TXNHEAD *hp;
	DB_TXNLIST *p;

	hp = (DB_TXNHEAD *)listp;
	while ((p = LIST_FIRST(&hp->head)) != LIST_END(&hp->head)) {
		LIST_REMOVE(p, links);
		__os_free(p, 0);
	}
	__os_free(listp, sizeof(DB_TXNHEAD));
}

/*
 * __db_txnlist_gen --
 *	Change the current generation number.
 *
 * PUBLIC: void __db_txnlist_gen __P((void *, int));
 */
void
__db_txnlist_gen(listp, incr)
	void *listp;
	int incr;
{
	DB_TXNHEAD *hp;

	/*
	 * During recovery generation numbers keep track of how many "restart"
	 * checkpoints we've seen.  Restart checkpoints occur whenever we take
	 * a checkpoint and there are no outstanding transactions.  When that
	 * happens, we can reset transaction IDs back to 1.  It always happens
	 * at recovery and it prevents us from exhausting the transaction IDs
	 * name space.
	 */
	hp = (DB_TXNHEAD *)listp;
	hp->generation += incr;
}

#ifdef DEBUG
/*
 * __db_txnlist_print --
 *	Print out the transaction list.
 *
 * PUBLIC: void __db_txnlist_print __P((void *));
 */
void
__db_txnlist_print(listp)
	void *listp;
{
	DB_TXNHEAD *hp;
	DB_TXNLIST *p;

	hp = (DB_TXNHEAD *)listp;
	printf("Maxid: %lu Generation: %lu\n", (u_long)hp->maxid,
	    (u_long)hp->generation);
	for (p = hp->head.lh_first; p != NULL; p = p->links.le_next)
		printf("TXNID: %lu(%lu)\n", (u_long)p->txnid,
		(u_long)p->generation);
}
#endif