xref: /titanic_44/usr/src/lib/krb5/plugins/kdb/db2/libdb2/btree/bt_overflow.c (revision 54925bf60766fbb4f1f2d7c843721406a7b7a3fb)
1  #pragma ident	"%Z%%M%	%I%	%E% SMI"
2  
3  /*-
4   * Copyright (c) 1990, 1993, 1994
5   *	The Regents of the University of California.  All rights reserved.
6   *
7   * This code is derived from software contributed to Berkeley by
8   * Mike Olson.
9   *
10   * Redistribution and use in source and binary forms, with or without
11   * modification, are permitted provided that the following conditions
12   * are met:
13   * 1. Redistributions of source code must retain the above copyright
14   *    notice, this list of conditions and the following disclaimer.
15   * 2. Redistributions in binary form must reproduce the above copyright
16   *    notice, this list of conditions and the following disclaimer in the
17   *    documentation and/or other materials provided with the distribution.
18   * 3. All advertising materials mentioning features or use of this software
19   *    must display the following acknowledgement:
20   *	This product includes software developed by the University of
21   *	California, Berkeley and its contributors.
22   * 4. Neither the name of the University nor the names of its contributors
23   *    may be used to endorse or promote products derived from this software
24   *    without specific prior written permission.
25   *
26   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36   * SUCH DAMAGE.
37   */
38  
39  #if defined(LIBC_SCCS) && !defined(lint)
40  static char sccsid[] = "@(#)bt_overflow.c	8.5 (Berkeley) 7/16/94";
41  #endif /* LIBC_SCCS and not lint */
42  
43  #include <sys/param.h>
44  
45  #include <stdio.h>
46  #include <stdlib.h>
47  #include <string.h>
48  
49  #include "db-int.h"
50  #include "btree.h"
51  
52  /*
53   * Big key/data code.
54   *
55   * Big key and data entries are stored on linked lists of pages.  The initial
56   * reference is byte string stored with the key or data and is the page number
57   * and size.  The actual record is stored in a chain of pages linked by the
58   * nextpg field of the PAGE header.
59   *
60   * The first page of the chain has a special property.  If the record is used
61   * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set
62   * in the header.
63   *
64   * XXX
65   * A single DBT is written to each chain, so a lot of space on the last page
66   * is wasted.  This is a fairly major bug for some data sets.
67   */
68  
69  /*
70   * __OVFL_GET -- Get an overflow key/data item.
71   *
72   * Parameters:
73   *	t:	tree
74   *	p:	pointer to { db_pgno_t, u_int32_t }
75   *	buf:	storage address
76   *	bufsz:	storage size
77   *
78   * Returns:
79   *	RET_ERROR, RET_SUCCESS
80   */
81  int
__ovfl_get(t,p,ssz,buf,bufsz)82  __ovfl_get(t, p, ssz, buf, bufsz)
83  	BTREE *t;
84  	void *p;
85  	size_t *ssz;
86  	void **buf;
87  	size_t *bufsz;
88  {
89  	PAGE *h;
90  	db_pgno_t pg;
91  	size_t nb, plen;
92  	u_int32_t sz;
93  
94  	memmove(&pg, p, sizeof(db_pgno_t));
95  	memmove(&sz, (char *)p + sizeof(db_pgno_t), sizeof(u_int32_t));
96  	*ssz = sz;
97  
98  #ifdef DEBUG
99  	if (pg == P_INVALID || sz == 0)
100  		abort();
101  #endif
102  	/* Make the buffer bigger as necessary. */
103  	if (*bufsz < sz) {
104  		*buf = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz));
105  		if (*buf == NULL)
106  			return (RET_ERROR);
107  		*bufsz = sz;
108  	}
109  
110  	/*
111  	 * Step through the linked list of pages, copying the data on each one
112  	 * into the buffer.  Never copy more than the data's length.
113  	 */
114  	plen = t->bt_psize - BTDATAOFF;
115  	for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) {
116  		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
117  			return (RET_ERROR);
118  
119  		nb = MIN(sz, plen);
120  		memmove(p, (char *)h + BTDATAOFF, nb);
121  		mpool_put(t->bt_mp, h, 0);
122  
123  		if ((sz -= nb) == 0)
124  			break;
125  	}
126  	return (RET_SUCCESS);
127  }
128  
129  /*
130   * __OVFL_PUT -- Store an overflow key/data item.
131   *
132   * Parameters:
133   *	t:	tree
134   *	data:	DBT to store
135   *	pgno:	storage page number
136   *
137   * Returns:
138   *	RET_ERROR, RET_SUCCESS
139   */
140  int
__ovfl_put(t,dbt,pg)141  __ovfl_put(t, dbt, pg)
142  	BTREE *t;
143  	const DBT *dbt;
144  	db_pgno_t *pg;
145  {
146  	PAGE *h, *last;
147  	void *p;
148  	db_pgno_t npg;
149  	size_t nb, plen;
150  	u_int32_t sz;
151  
152  	/*
153  	 * Allocate pages and copy the key/data record into them.  Store the
154  	 * number of the first page in the chain.
155  	 */
156  	plen = t->bt_psize - BTDATAOFF;
157  	for (last = NULL, p = dbt->data, sz = dbt->size;;
158  	    p = (char *)p + plen, last = h) {
159  		if ((h = __bt_new(t, &npg)) == NULL)
160  			return (RET_ERROR);
161  
162  		h->pgno = npg;
163  		h->nextpg = h->prevpg = P_INVALID;
164  		h->flags = P_OVERFLOW;
165  		h->lower = h->upper = 0;
166  
167  		nb = MIN(sz, plen);
168  		memmove((char *)h + BTDATAOFF, p, nb);
169  
170  		if (last) {
171  			last->nextpg = h->pgno;
172  			mpool_put(t->bt_mp, last, MPOOL_DIRTY);
173  		} else
174  			*pg = h->pgno;
175  
176  		if ((sz -= nb) == 0) {
177  			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
178  			break;
179  		}
180  	}
181  	return (RET_SUCCESS);
182  }
183  
184  /*
185   * __OVFL_DELETE -- Delete an overflow chain.
186   *
187   * Parameters:
188   *	t:	tree
189   *	p:	pointer to { db_pgno_t, u_int32_t }
190   *
191   * Returns:
192   *	RET_ERROR, RET_SUCCESS
193   */
194  int
__ovfl_delete(t,p)195  __ovfl_delete(t, p)
196  	BTREE *t;
197  	void *p;
198  {
199  	PAGE *h;
200  	db_pgno_t pg;
201  	size_t plen;
202  	u_int32_t sz;
203  
204  	memmove(&pg, p, sizeof(db_pgno_t));
205  	memmove(&sz, (char *)p + sizeof(db_pgno_t), sizeof(u_int32_t));
206  
207  #ifdef DEBUG
208  	if (pg == P_INVALID || sz == 0)
209  		abort();
210  #endif
211  	if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
212  		return (RET_ERROR);
213  
214  	/* Don't delete chains used by internal pages. */
215  	if (h->flags & P_PRESERVE) {
216  		mpool_put(t->bt_mp, h, 0);
217  		return (RET_SUCCESS);
218  	}
219  
220  	/* Step through the chain, calling the free routine for each page. */
221  	for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) {
222  		pg = h->nextpg;
223  		__bt_free(t, h);
224  		if (sz <= plen)
225  			break;
226  		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
227  			return (RET_ERROR);
228  	}
229  	return (RET_SUCCESS);
230  }
231