[unix-history] / usr / src / lib / libc / db / btree / seq.c

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)seq.c	5.4 (Berkeley) 3/3/91";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <errno.h>
#include <db.h>
#include <stdlib.h>
#include "btree.h"

/*
 *  _BT_SEQINIT -- Initialize a sequential scan on the btree.
 *
 *	Sets the tree's notion of the current scan location correctly
 *	given a key and a direction.
 *
 *	Parameters:
 *		t -- tree in which to initialize scan
 *		key -- key for initial scan position
 *		flags -- R_NEXT, R_PREV
 *
 *	Returns:
 *		RET_SUCCESS, RET_ERROR, or RET_SPECIAL if there's no data
 *		in the tree to scan.
 *
 *	Side Effects:
 *		Changes current scan position for the tree.  Almost certainly
 *		changes current page, as well.  Sets BTF_SEQINIT bit in tree
 *		flags, so that we know we've initialized a scan.
 */

int
_bt_seqinit(t, key, flags)
	BTREE_P t;
	DBT *key;
	int flags;
{
	BTITEM *item;
	BTHEADER *h;
	CURSOR *c;
	IDATUM *id;
	index_t last;

	/*
	 *  Figure out if we really have to search for the key that the
	 *  user supplied.  If key is null, then this is an unkeyed scan
	 *  and we can just start from an endpoint.
	 */

	c = &(t->bt_cursor);

	if (flags == R_CURSOR) {
		if (key->data != (u_char *) NULL) {

			/* key supplied, find first instance of it */
			item = _bt_first(t, key);
			c->c_index = item->bti_index;
			c->c_pgno = t->bt_curpage->h_pgno;
		} else {
			errno = EINVAL;
			return (RET_ERROR);
		}

	} else {

		/*
		 *  Unkeyed scan.  For backward scans, find the last item
		 *  in the tree; for forward scans, find the first item.
		 */

		if (_bt_getpage(t, (pgno_t) P_ROOT) == RET_ERROR)
			return (RET_ERROR);
		h = t->bt_curpage;
		if (flags == R_LAST || flags == R_PREV) {

			/* backward scan */
			while (!(h->h_flags & F_LEAF)) {
				last = NEXTINDEX(h) - 1;
				id = (IDATUM *) GETDATUM(h,last);
				if (_bt_getpage(t, id->i_pgno) == RET_ERROR)
					return (RET_ERROR);
				h = t->bt_curpage;
			}

			/* skip empty pages */
			while (NEXTINDEX(h) == 0 && h->h_prevpg != P_NONE) {
				if (_bt_getpage(t, h->h_prevpg) == RET_ERROR)
					return (RET_ERROR);
				h = t->bt_curpage;
			}

			c->c_pgno = h->h_pgno;
			if (NEXTINDEX(h) > 0)
				c->c_index = NEXTINDEX(h) - 1;
			else
				c->c_index = 0;
		} else if (flags == R_FIRST || flags == R_NEXT) {
			/* forward scan */
			while (!(h->h_flags & F_LEAF)) {
				id = (IDATUM *) GETDATUM(h,0);
				if (_bt_getpage(t, id->i_pgno) == RET_ERROR)
					return (RET_ERROR);
				h = t->bt_curpage;
			}

			/* skip empty pages */
			while (NEXTINDEX(h) == 0 && h->h_nextpg != P_NONE) {
				if (_bt_getpage(t, h->h_nextpg) == RET_ERROR)
					return (RET_ERROR);
				h = t->bt_curpage;
			}

			c->c_pgno = h->h_pgno;
			c->c_index = 0;
		} else {
			/* no flags passed in */
			errno = EINVAL;
			return (RET_ERROR);
		}
	}

	/* okay, scan is initialized */
	t->bt_flags |= BTF_SEQINIT;

	/* don't need the descent stack anymore */
	while (_bt_pop(t) != P_NONE)
		continue;

	if (c->c_index == NEXTINDEX(t->bt_curpage))
		return (RET_SPECIAL);

	return (RET_SUCCESS);
}

/*
 *  _BT_SEQADVANCE -- Advance the sequential scan on this tree.
 *
 *	Moves the current location pointer for the scan on this tree one
 *	spot in the requested direction.
 *
 *	Parameters:
 *		t -- btree being scanned
 *		flags -- for R_NEXT, R_PREV
 *
 *	Returns:
 *		RET_SUCCESS, RET_ERROR, or RET_SPECIAL if there is no
 *		more data in the specified direction.
 *
 *	Side Effects:
 *		May change current page.
 */

int
_bt_seqadvance(t, flags)
	BTREE_P t;
	int flags;
{
	BTHEADER *h;
	CURSOR *c;
	index_t index;

	c = &(t->bt_cursor);
	index = c->c_index;

	if (_bt_getpage(t, c->c_pgno) == RET_ERROR)
		return (RET_ERROR);
	h = t->bt_curpage;

	/* by the time we get here, don't need the cursor key anymore */
	if (c->c_key != (char *) NULL)
		(void) free(c->c_key);

	if (flags == R_NEXT) {

		/*
		 *  This is a forward scan.  If the cursor is pointing
		 *  at a virtual record (that is, it was pointing at
		 *  a record that got deleted), then we should return
		 *  the record it's pointing at now.  Otherwise, we
		 *  should advance the scan.  In either case, we need
		 *  to be careful not to run off the end of the current
		 *  page.
		 */

		if (c->c_flags & CRSR_BEFORE) {

			if (index >= NEXTINDEX(h)) {
				/* out of items on this page, get next page */
				if (h->h_nextpg == P_NONE) {
					/* tell caller we're done... */
					c->c_index = NEXTINDEX(h);
					return (RET_SPECIAL);
				}

				/* skip empty pages */
				do {
					if (_bt_getpage(t, h->h_nextpg)
					    == RET_ERROR) {
						c->c_index = NEXTINDEX(h);
						return (RET_ERROR);
					}
					h = t->bt_curpage;
					c->c_pgno = h->h_pgno;
				} while (NEXTINDEX(h) == 0
					 && h->h_nextpg != P_NONE);

				if (NEXTINDEX(h) == 0) {
					/* tell caller we're done */
					c->c_index = NEXTINDEX(h);
					return (RET_SPECIAL);
				}
				index = 0;
			}
			c->c_flags &= ~CRSR_BEFORE;

		} else if (++index >= NEXTINDEX(h)) {

			/* out of items on this page, get next page */
			if (h->h_nextpg == P_NONE) {
				/* tell caller we're done... */
				c->c_index = NEXTINDEX(h);
				return (RET_SPECIAL);
			}

			/* skip empty pages */
			do {
				if (_bt_getpage(t, h->h_nextpg) == RET_ERROR) {
					c->c_index = NEXTINDEX(h);
					return (RET_ERROR);
				}
				h = t->bt_curpage;
				c->c_pgno = h->h_pgno;
			} while (NEXTINDEX(h) == 0 && h->h_nextpg != P_NONE);

			if (NEXTINDEX(h) == 0) {
				/* tell caller we're done */
				c->c_index = NEXTINDEX(h);
				return (RET_SPECIAL);
			}
			index = 0;
		}
	} else if (flags == R_PREV) {

		/* for backward scans, life is substantially easier */
		c->c_flags &= ~CRSR_BEFORE;
		if (c->c_key != (char *) NULL) {
			(void) free(c->c_key);
			c->c_key = (char *) NULL;
		}

		if (index == 0) {

			/* we may be done */
			c->c_index = 0;

			/* out of items on this page, get next page */
			if (h->h_prevpg == P_NONE)
				return (RET_SPECIAL);

			/* skip empty pages */
			do {
				if (_bt_getpage(t, h->h_prevpg) == RET_ERROR)
					return (RET_ERROR);
				h = t->bt_curpage;
				c->c_pgno = h->h_pgno;
			} while (NEXTINDEX(h) == 0 && h->h_prevpg != P_NONE);

			if (NEXTINDEX(h) == 0)
				return (RET_SPECIAL);

			index = NEXTINDEX(h) - 1;
		} else
			--index;
	} else {
		/* must specify a direction */
		errno = EINVAL;
		return (RET_ERROR);
	}

	c->c_index = index;
	return (RET_SUCCESS);
}
Commit	Line	Data
4e820f17 MO	1	/*-
	2	* Copyright (c) 1990 The Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* This code is derived from software contributed to Berkeley by
	6	* Mike Olson.
	7	*
af359dea C	8	* Redistribution and use in source and binary forms, with or without
	9	* modification, are permitted provided that the following conditions
	10	* are met:
	11	* 1. Redistributions of source code must retain the above copyright
	12	* notice, this list of conditions and the following disclaimer.
	13	* 2. Redistributions in binary form must reproduce the above copyright
	14	* notice, this list of conditions and the following disclaimer in the
	15	* documentation and/or other materials provided with the distribution.
	16	* 3. All advertising materials mentioning features or use of this software
	17	* must display the following acknowledgement:
	18	* This product includes software developed by the University of
	19	* California, Berkeley and its contributors.
	20	* 4. Neither the name of the University nor the names of its contributors
	21	* may be used to endorse or promote products derived from this software
	22	* without specific prior written permission.
	23	*
	24	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	25	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	26	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	27	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	28	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	29	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	30	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	31	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	32	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	33	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	34	* SUCH DAMAGE.
4e820f17 MO	35	*/
	36
	37	#if defined(LIBC_SCCS) && !defined(lint)
af359dea	38	static char sccsid[] = "@(#)seq.c 5.4 (Berkeley) 3/3/91";
4e820f17 MO	39	#endif /* LIBC_SCCS and not lint */
	40
	41	#include <sys/types.h>
fb91cf55	42	#include <errno.h>
4e820f17	43	#include <db.h>
fb91cf55	44	#include <stdlib.h>
4e820f17 MO	45	#include "btree.h"
	46
	47	/*
	48	* _BT_SEQINIT -- Initialize a sequential scan on the btree.
	49	*
	50	* Sets the tree's notion of the current scan location correctly
	51	* given a key and a direction.
	52	*
	53	* Parameters:
	54	* t -- tree in which to initialize scan
	55	* key -- key for initial scan position
	56	* flags -- R_NEXT, R_PREV
	57	*
	58	* Returns:
	59	* RET_SUCCESS, RET_ERROR, or RET_SPECIAL if there's no data
	60	* in the tree to scan.
	61	*
	62	* Side Effects:
	63	* Changes current scan position for the tree. Almost certainly
	64	* changes current page, as well. Sets BTF_SEQINIT bit in tree
	65	* flags, so that we know we've initialized a scan.
	66	*/
	67
	68	int
	69	_bt_seqinit(t, key, flags)
	70	BTREE_P t;
	71	DBT *key;
	72	int flags;
	73	{
	74	BTITEM *item;
	75	BTHEADER *h;
	76	CURSOR *c;
	77	IDATUM *id;
	78	index_t last;
	79
	80	/*
	81	* Figure out if we really have to search for the key that the
	82	* user supplied. If key is null, then this is an unkeyed scan
	83	* and we can just start from an endpoint.
	84	*/
	85
	86	c = &(t->bt_cursor);
	87
	88	if (flags == R_CURSOR) {
7d2840f6	89	if (key->data != (u_char *) NULL) {
4e820f17 MO	90
	91	/* key supplied, find first instance of it */
	92	item = _bt_first(t, key);
	93	c->c_index = item->bti_index;
	94	c->c_pgno = t->bt_curpage->h_pgno;
	95	} else {
	96	errno = EINVAL;
	97	return (RET_ERROR);
	98	}
	99
	100	} else {
	101
	102	/*
	103	* Unkeyed scan. For backward scans, find the last item
	104	* in the tree; for forward scans, find the first item.
	105	*/
	106
	107	if (_bt_getpage(t, (pgno_t) P_ROOT) == RET_ERROR)
	108	return (RET_ERROR);
	109	h = t->bt_curpage;
	110	if (flags == R_LAST \|\| flags == R_PREV) {
	111
	112	/* backward scan */
	113	while (!(h->h_flags & F_LEAF)) {
	114	last = NEXTINDEX(h) - 1;
	115	id = (IDATUM *) GETDATUM(h,last);
	116	if (_bt_getpage(t, id->i_pgno) == RET_ERROR)
	117	return (RET_ERROR);
	118	h = t->bt_curpage;
	119	}
	120
	121	/* skip empty pages */
	122	while (NEXTINDEX(h) == 0 && h->h_prevpg != P_NONE) {
	123	if (_bt_getpage(t, h->h_prevpg) == RET_ERROR)
	124	return (RET_ERROR);
	125	h = t->bt_curpage;
	126	}
	127
	128	c->c_pgno = h->h_pgno;
	129	if (NEXTINDEX(h) > 0)
	130	c->c_index = NEXTINDEX(h) - 1;
	131	else
	132	c->c_index = 0;
	133	} else if (flags == R_FIRST \|\| flags == R_NEXT) {
	134	/* forward scan */
	135	while (!(h->h_flags & F_LEAF)) {
	136	id = (IDATUM *) GETDATUM(h,0);
	137	if (_bt_getpage(t, id->i_pgno) == RET_ERROR)
	138	return (RET_ERROR);
	139	h = t->bt_curpage;
	140	}
	141
	142	/* skip empty pages */
	143	while (NEXTINDEX(h) == 0 && h->h_nextpg != P_NONE) {
	144	if (_bt_getpage(t, h->h_nextpg) == RET_ERROR)
	145	return (RET_ERROR);
	146	h = t->bt_curpage;
	147	}
	148
	149	c->c_pgno = h->h_pgno;
	150	c->c_index = 0;
	151	} else {
	152	/* no flags passed in */
	153	errno = EINVAL;
154	return (RET_ERROR);
155	}
156	}
157
158	/* okay, scan is initialized */
159	t->bt_flags \|= BTF_SEQINIT;
160
1a18d2ca MO	161	/* don't need the descent stack anymore */
	162	while (_bt_pop(t) != P_NONE)
	163	continue;
	164
4e820f17 MO	165	if (c->c_index == NEXTINDEX(t->bt_curpage))
	166	return (RET_SPECIAL);
	167
	168	return (RET_SUCCESS);
	169	}
	170
	171	/*
	172	* _BT_SEQADVANCE -- Advance the sequential scan on this tree.
	173	*
	174	* Moves the current location pointer for the scan on this tree one
	175	* spot in the requested direction.
	176	*
	177	* Parameters:
	178	* t -- btree being scanned
	179	* flags -- for R_NEXT, R_PREV
	180	*
	181	* Returns:
	182	* RET_SUCCESS, RET_ERROR, or RET_SPECIAL if there is no
	183	* more data in the specified direction.
	184	*
	185	* Side Effects:
	186	* May change current page.
	187	*/
	188
	189	int
	190	_bt_seqadvance(t, flags)
	191	BTREE_P t;
	192	int flags;
	193	{
	194	BTHEADER *h;
	195	CURSOR *c;
	196	index_t index;
	197
	198	c = &(t->bt_cursor);
	199	index = c->c_index;
	200
	201	if (_bt_getpage(t, c->c_pgno) == RET_ERROR)
	202	return (RET_ERROR);
	203	h = t->bt_curpage;
	204
	205	/* by the time we get here, don't need the cursor key anymore */
	206	if (c->c_key != (char *) NULL)
	207	(void) free(c->c_key);
	208
	209	if (flags == R_NEXT) {
	210
	211	/*
	212	* This is a forward scan. If the cursor is pointing
	213	* at a virtual record (that is, it was pointing at
	214	* a record that got deleted), then we should return
	215	* the record it's pointing at now. Otherwise, we
	216	* should advance the scan. In either case, we need
	217	* to be careful not to run off the end of the current
	218	* page.
	219	*/
	220
	221	if (c->c_flags & CRSR_BEFORE) {
	222
	223	if (index >= NEXTINDEX(h)) {
	224	/* out of items on this page, get next page */
	225	if (h->h_nextpg == P_NONE) {
	226	/* tell caller we're done... */
	227	c->c_index = NEXTINDEX(h);
	228	return (RET_SPECIAL);
229	}
230
231	/* skip empty pages */
232	do {
233	if (_bt_getpage(t, h->h_nextpg)
234	== RET_ERROR) {
235	c->c_index = NEXTINDEX(h);
236	return (RET_ERROR);
237	}
238	h = t->bt_curpage;
239	c->c_pgno = h->h_pgno;
240	} while (NEXTINDEX(h) == 0
241	&& h->h_nextpg != P_NONE);
242
243	if (NEXTINDEX(h) == 0) {
244	/* tell caller we're done */
245	c->c_index = NEXTINDEX(h);
246	return (RET_SPECIAL);
247	}
248	index = 0;
249	}
250	c->c_flags &= ~CRSR_BEFORE;
251
252	} else if (++index >= NEXTINDEX(h)) {
253
254	/* out of items on this page, get next page */
255	if (h->h_nextpg == P_NONE) {
256	/* tell caller we're done... */
257	c->c_index = NEXTINDEX(h);
258	return (RET_SPECIAL);
259	}
260
261	/* skip empty pages */
262	do {
263	if (_bt_getpage(t, h->h_nextpg) == RET_ERROR) {
264	c->c_index = NEXTINDEX(h);
265	return (RET_ERROR);
266	}
267	h = t->bt_curpage;
268	c->c_pgno = h->h_pgno;
269	} while (NEXTINDEX(h) == 0 && h->h_nextpg != P_NONE);
270
271	if (NEXTINDEX(h) == 0) {
272	/* tell caller we're done */
273	c->c_index = NEXTINDEX(h);
274	return (RET_SPECIAL);
275	}
276	index = 0;
277	}
278	} else if (flags == R_PREV) {
279
280	/* for backward scans, life is substantially easier */
281	c->c_flags &= ~CRSR_BEFORE;
282	if (c->c_key != (char *) NULL) {
283	(void) free(c->c_key);
284	c->c_key = (char *) NULL;
285	}
286
287	if (index == 0) {
288
289	/* we may be done */
290	c->c_index = 0;
291
292	/* out of items on this page, get next page */
293	if (h->h_prevpg == P_NONE)
294	return (RET_SPECIAL);
295
296	/* skip empty pages */
297	do {
298	if (_bt_getpage(t, h->h_prevpg) == RET_ERROR)
299	return (RET_ERROR);
300	h = t->bt_curpage;
301	c->c_pgno = h->h_pgno;
302	} while (NEXTINDEX(h) == 0 && h->h_prevpg != P_NONE);
303
304	if (NEXTINDEX(h) == 0)
305	return (RET_SPECIAL);
306
307	index = NEXTINDEX(h) - 1;
308	} else
309	--index;
310	} else {
311	/* must specify a direction */
312	errno = EINVAL;
313	return (RET_ERROR);
314	}
315
316	c->c_index = index;
317	return (RET_SUCCESS);
318	}