bt_recno.c

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997-2002
 *	Sleepycat Software.  All rights reserved.
 */

#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: bt_recno.c,v 11.106 2002/08/16 04:56:30 ubell Exp $";
#endif /* not lint */

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

#include <limits.h>
#include <stdio.h>
#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/db_page.h"
#include "dbinc/btree.h"
#include "dbinc/db_shash.h"
#include "dbinc/lock.h"

static int  __ram_add __P((DBC *, db_recno_t *, DBT *, u_int32_t, u_int32_t));
static int  __ram_source __P((DB *));
static int  __ram_sread __P((DBC *, db_recno_t));
static int  __ram_update __P((DBC *, db_recno_t, int));

/*
 * In recno, there are two meanings to the on-page "deleted" flag.  If we're
 * re-numbering records, it means the record was implicitly created.  We skip
 * over implicitly created records if doing a cursor "next" or "prev", and
 * return DB_KEYEMPTY if they're explicitly requested..  If not re-numbering
 * records, it means that the record was implicitly created, or was deleted.
 * We skip over implicitly created or deleted records if doing a cursor "next"
 * or "prev", and return DB_KEYEMPTY if they're explicitly requested.
 *
 * If we're re-numbering records, then we have to detect in the cursor that
 * a record was deleted, and adjust the cursor as necessary on the next get.
 * If we're not re-numbering records, then we can detect that a record has
 * been deleted by looking at the actual on-page record, so we completely
 * ignore the cursor's delete flag.  This is different from the B+tree code.
 * It also maintains whether the cursor references a deleted record in the
 * cursor, and it doesn't always check the on-page value.
 */
#define	CD_SET(cp) {							\
	if (F_ISSET(cp, C_RENUMBER))					\
		F_SET(cp, C_DELETED);					\
}
#define	CD_CLR(cp) {							\
	if (F_ISSET(cp, C_RENUMBER)) {					\
		F_CLR(cp, C_DELETED);					\
		cp->order = INVALID_ORDER;				\
	}								\
}
#define	CD_ISSET(cp)							\
	(F_ISSET(cp, C_RENUMBER) && F_ISSET(cp, C_DELETED))

/*
 * Macros for comparing the ordering of two cursors.
 * cp1 comes before cp2 iff one of the following holds:
 *	cp1's recno is less than cp2's recno
 *	recnos are equal, both deleted, and cp1's order is less than cp2's
 *	recnos are equal, cp1 deleted, and cp2 not deleted
 */
#define	C_LESSTHAN(cp1, cp2)						\
    (((cp1)->recno < (cp2)->recno) ||					\
    (((cp1)->recno == (cp2)->recno) &&					\
    ((CD_ISSET((cp1)) && CD_ISSET((cp2)) && (cp1)->order < (cp2)->order) || \
    (CD_ISSET((cp1)) && !CD_ISSET((cp2))))))

/*
 * cp1 is equal to cp2 iff their recnos and delete flags are identical,
 * and if the delete flag is set their orders are also identical.
 */
#define	C_EQUAL(cp1, cp2)						\
    ((cp1)->recno == (cp2)->recno && CD_ISSET((cp1)) == CD_ISSET((cp2)) && \
    (!CD_ISSET((cp1)) || (cp1)->order == (cp2)->order))

/*
 * Do we need to log the current cursor adjustment?
 */
#define	CURADJ_LOG(dbc)							\
	(DBC_LOGGING((dbc)) && (dbc)->txn != NULL && (dbc)->txn->parent != NULL)

/*
 * After a search, copy the found page into the cursor, discarding any
 * currently held lock.
 */
#define	STACK_TO_CURSOR(cp) {						\
	(cp)->page = (cp)->csp->page;					\
	(cp)->pgno = (cp)->csp->page->pgno;				\
	(cp)->indx = (cp)->csp->indx;					\
	(void)__TLPUT(dbc, (cp)->lock);					\
	(cp)->lock = (cp)->csp->lock;					\
	(cp)->lock_mode = (cp)->csp->lock_mode;				\
}

/*
 * __ram_open --
 *	Recno open function.
 *
 * PUBLIC: int __ram_open __P((DB *,
 * PUBLIC:      DB_TXN *, const char *, db_pgno_t, u_int32_t));
 */
int
__ram_open(dbp, txn, name, base_pgno, flags)
	DB *dbp;
	DB_TXN *txn;
	const char *name;
	db_pgno_t base_pgno;
	u_int32_t flags;
{
	BTREE *t;
	DBC *dbc;
	int ret, t_ret;

	COMPQUIET(name, NULL);
	t = dbp->bt_internal;

	/* Initialize the remaining fields/methods of the DB. */
	dbp->stat = __bam_stat;

	/* Start up the tree. */
	if ((ret = __bam_read_root(dbp, txn, base_pgno, flags)) != 0)
		return (ret);

	/*
	 * If the user specified a source tree, open it and map it in.
	 *
	 * !!!
	 * We don't complain if the user specified transactions or threads.
	 * It's possible to make it work, but you'd better know what you're
	 * doing!
	 */
	if (t->re_source != NULL && (ret = __ram_source(dbp)) != 0)
		return (ret);

	/* If we're snapshotting an underlying source file, do it now. */
	if (F_ISSET(dbp, DB_AM_SNAPSHOT)) {
		/* Allocate a cursor. */
		if ((ret = dbp->cursor(dbp, NULL, &dbc, 0)) != 0)
			return (ret);

		/* Do the snapshot. */
		if ((ret = __ram_update(dbc,
		    DB_MAX_RECORDS, 0)) != 0 && ret == DB_NOTFOUND)
			ret = 0;

		/* Discard the cursor. */
		if ((t_ret = dbc->c_close(dbc)) != 0 && ret == 0)
			ret = t_ret;
	}

	return (ret);
}

/*
 * __ram_append --
 *	Recno append function.
 *
 * PUBLIC: int __ram_append __P((DBC *, DBT *, DBT *));
 */
int
__ram_append(dbc, key, data)
	DBC *dbc;
	DBT *key, *data;
{
	BTREE_CURSOR *cp;
	int ret;

	cp = (BTREE_CURSOR *)dbc->internal;

	/*
	 * Make sure we've read in all of the backing source file.  If
	 * we found the record or it simply didn't exist, add the
	 * user's record.
	 */
	ret = __ram_update(dbc, DB_MAX_RECORDS, 0);
	if (ret == 0 || ret == DB_NOTFOUND)
		ret = __ram_add(dbc, &cp->recno, data, DB_APPEND, 0);

	/* Return the record number. */
	if (ret == 0)
		ret = __db_retcopy(dbc->dbp->dbenv, key, &cp->recno,
		    sizeof(cp->recno), &dbc->rkey->data, &dbc->rkey->ulen);

	return (ret);
}

/*
 * __ram_c_del --
 *	Recno cursor->c_del function.
 *
 * PUBLIC: int __ram_c_del __P((DBC *));
 */
int
__ram_c_del(dbc)
	DBC *dbc;
{
	BKEYDATA bk;
	BTREE *t;
	BTREE_CURSOR *cp;
	DB *dbp;
	DB_LSN lsn;
	DBT hdr, data;
	EPG *epg;
	int exact, ret, stack;

	dbp = dbc->dbp;
	cp = (BTREE_CURSOR *)dbc->internal;
	t = dbp->bt_internal;
	stack = 0;

	/*
	 * The semantics of cursors during delete are as follows: in
	 * non-renumbering recnos, records are replaced with a marker
	 * containing a delete flag.  If the record referenced by this cursor
	 * has already been deleted, we will detect that as part of the delete
	 * operation, and fail.
	 *
	 * In renumbering recnos, cursors which represent deleted items
	 * are flagged with the C_DELETED flag, and it is an error to
	 * call c_del a second time without an intervening cursor motion.
	 */
	if (CD_ISSET(cp))
		return (DB_KEYEMPTY);

	/* Search the tree for the key; delete only deletes exact matches. */
	if ((ret = __bam_rsearch(dbc, &cp->recno, S_DELETE, 1, &exact)) != 0)
		goto err;
	if (!exact) {
		ret = DB_NOTFOUND;
		goto err;
	}
	stack = 1;

	/* Copy the page into the cursor. */
	STACK_TO_CURSOR(cp);

	/*
	 * If re-numbering records, the on-page deleted flag can only mean
	 * that this record was implicitly created.  Applications aren't
	 * permitted to delete records they never created, return an error.
	 *
	 * If not re-numbering records, the on-page deleted flag means that
	 * this record was implicitly created, or, was deleted at some time.
	 * The former is an error because applications aren't permitted to
	 * delete records they never created, the latter is an error because
	 * if the record was "deleted", we could never have found it.
	 */
	if (B_DISSET(GET_BKEYDATA(dbp, cp->page, cp->indx)->type)) {
		ret = DB_KEYEMPTY;
		goto err;
	}

	if (F_ISSET(cp, C_RENUMBER)) {
		/* Delete the item, adjust the counts, adjust the cursors. */
		if ((ret = __bam_ditem(dbc, cp->page, cp->indx)) != 0)
			goto err;
		__bam_adjust(dbc, -1);
		if (__ram_ca(dbc, CA_DELETE) > 0 &&
		    CURADJ_LOG(dbc) && (ret = __bam_rcuradj_log(dbp, dbc->txn,
		    &lsn, 0, CA_DELETE, cp->root, cp->recno, cp->order)) != 0)
			goto err;

		/*
		 * If the page is empty, delete it.
		 *
		 * We never delete a root page.  First, root pages of primary
		 * databases never go away, recno or otherwise.  However, if
		 * it's the root page of an off-page duplicates database, then
		 * it can be deleted.   We don't delete it here because we have
		 * no way of telling the primary database page holder (e.g.,
		 * the hash access method) that its page element should cleaned
		 * up because the underlying tree is gone.  So, we keep the page
		 * around until the last cursor referencing the empty tree is
		 * are closed, and then clean it up.
		 */
		if (NUM_ENT(cp->page) == 0 && PGNO(cp->page) != cp->root) {
			/*
			 * We already have a locked stack of pages.  However,
			 * there are likely entries in the stack that aren't
			 * going to be emptied by removing the single reference
			 * to the emptied page (or one of its parents).
			 */
			for (epg = cp->csp; epg >= cp->sp; --epg)
				if (NUM_ENT(epg->page) > 1)
					break;

			/*
			 * We want to delete a single item out of the last page
			 * that we're not deleting.
			 */
			ret = __bam_dpages(dbc, epg);

			/*
			 * Regardless of the return from __bam_dpages, it will
			 * discard our stack and pinned page.
			 */
			stack = 0;
			cp->page = NULL;
		}
	} else {
		/* Use a delete/put pair to replace the record with a marker. */
		if ((ret = __bam_ditem(dbc, cp->page, cp->indx)) != 0)
			goto err;

		B_TSET(bk.type, B_KEYDATA, 1);
		bk.len = 0;
		memset(&hdr, 0, sizeof(hdr));
		hdr.data = &bk;
		hdr.size = SSZA(BKEYDATA, data);
		memset(&data, 0, sizeof(data));
		data.data = (void *)"";
		data.size = 0;
		if ((ret = __db_pitem(dbc,
		    cp->page, cp->indx, BKEYDATA_SIZE(0), &hdr, &data)) != 0)
			goto err;
	}

	t->re_modified = 1;

err:	if (stack)
		__bam_stkrel(dbc, STK_CLRDBC);

	return (ret);
}

/*
 * __ram_c_get --
 *	Recno cursor->c_get function.
 *
 * PUBLIC: int __ram_c_get
 * PUBLIC:     __P((DBC *, DBT *, DBT *, u_int32_t, db_pgno_t *));
 */
int
__ram_c_get(dbc, key, data, flags, pgnop)
	DBC *dbc;
	DBT *key, *data;
	u_int32_t flags;
	db_pgno_t *pgnop;
{
	BTREE_CURSOR *cp;
	DB *dbp;
	int cmp, exact, ret;

	COMPQUIET(pgnop, NULL);

	dbp = dbc->dbp;
	cp = (BTREE_CURSOR *)dbc->internal;

	LF_CLR(DB_MULTIPLE|DB_MULTIPLE_KEY);
retry:	switch (flags) {
	case DB_CURRENT:
		/*
		 * If we're using mutable records and the deleted flag is
		 * set, the cursor is pointing at a nonexistent record;
		 * return an error.
		 */
		if (CD_ISSET(cp))
			return (DB_KEYEMPTY);
		break;
	case DB_NEXT_DUP:
		/*
		 * If we're not in an off-page dup set, we know there's no
		 * next duplicate since recnos don't have them.  If we
		 * are in an off-page dup set, the next item assuredly is
		 * a dup, so we set flags to DB_NEXT and keep going.
		 */
		if (!F_ISSET(dbc, DBC_OPD))
			return (DB_NOTFOUND);
		/* FALLTHROUGH */
	case DB_NEXT_NODUP:
		/*
		 * Recno databases don't have duplicates, set flags to DB_NEXT
		 * and keep going.
		 */
		/* FALLTHROUGH */
	case DB_NEXT:
		flags = DB_NEXT;
		/*
		 * If record numbers are mutable: if we just deleted a record,
		 * we have to avoid incrementing the record number so that we
		 * return the right record by virtue of renumbering the tree.
		 */
		if (CD_ISSET(cp))
			break;

		if (cp->recno != RECNO_OOB) {
			++cp->recno;
			break;
		}
		/* FALLTHROUGH */
	case DB_FIRST:
		flags = DB_NEXT;
		cp->recno = 1;
		break;
	case DB_PREV_NODUP:
		/*
		 * Recno databases don't have duplicates, set flags to DB_PREV
		 * and keep going.
		 */
		/* FALLTHROUGH */
	case DB_PREV:
		flags = DB_PREV;
		if (cp->recno != RECNO_OOB) {
			if (cp->recno == 1) {
				ret = DB_NOTFOUND;
				goto err;
			}
			--cp->recno;
			break;
		}
		/* FALLTHROUGH */
	case DB_LAST:
		flags = DB_PREV;
		if (((ret = __ram_update(dbc,
		    DB_MAX_RECORDS, 0)) != 0) && ret != DB_NOTFOUND)
			goto err;
		if ((ret = __bam_nrecs(dbc, &cp->recno)) != 0)
			goto err;
		if (cp->recno == 0) {
			ret = DB_NOTFOUND;
			goto err;
		}
		break;
	case DB_GET_BOTHC:
		/*
		 * If we're doing a join and these are offpage dups,
		 * we want to keep searching forward from after the
		 * current cursor position.  Increment the recno by 1,
		 * then proceed as for a DB_SET.
		 *
		 * Otherwise, we know there are no additional matching
		 * data, as recnos don't have dups.  return DB_NOTFOUND.
		 */
		if (F_ISSET(dbc, DBC_OPD)) {
			cp->recno++;