qam.c   [plain text]

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1999-2003
 *	Sleepycat Software.  All rights reserved.
 */

#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: qam.c,v 1.2 2004/03/30 01:23:55 jtownsen Exp $";
#endif /* not lint */

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

#include <string.h>
#endif

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

static int __qam_bulk __P((DBC *, DBT *, u_int32_t));
static int __qam_c_close __P((DBC *, db_pgno_t, int *));
static int __qam_c_del __P((DBC *));
static int __qam_c_destroy __P((DBC *));
static int __qam_c_get __P((DBC *, DBT *, DBT *, u_int32_t, db_pgno_t *));
static int __qam_c_put __P((DBC *, DBT *, DBT *, u_int32_t, db_pgno_t *));
static int __qam_consume __P((DBC *, QMETA *, db_recno_t));
static int __qam_getno __P((DB *, const DBT *, db_recno_t *));

/*
 * __qam_position --
 *	Position a queued access method cursor at a record.  This returns
 *	the page locked.  *exactp will be set if the record is valid.
 * PUBLIC: int __qam_position
 * PUBLIC:       __P((DBC *, db_recno_t *, qam_position_mode, int *));
 */
int
__qam_position(dbc, recnop, mode, exactp)
	DBC *dbc;		/* open cursor */
	db_recno_t *recnop;	/* pointer to recno to find */
	qam_position_mode mode;/* locking: read or write */
	int *exactp;		/* indicate if it was found */
{
	QUEUE_CURSOR *cp;
	DB *dbp;
	QAMDATA  *qp;
	db_pgno_t pg;
	int ret;

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

	/* Fetch the page for this recno. */
	pg = QAM_RECNO_PAGE(dbp, *recnop);

	if ((ret = __db_lget(dbc, 0, pg, mode == QAM_READ ?
	    DB_LOCK_READ : DB_LOCK_WRITE, 0, &cp->lock)) != 0)
		return (ret);
	cp->page = NULL;
	*exactp = 0;
	if ((ret = __qam_fget(dbp, &pg,
	    mode == QAM_WRITE ? DB_MPOOL_CREATE : 0, &cp->page)) != 0) {
		/* We did not fetch it, we can release the lock. */
		(void)__LPUT(dbc, cp->lock);
		if (mode != QAM_WRITE &&
		    (ret == DB_PAGE_NOTFOUND || ret == ENOENT))
			return (0);
		return (ret);
	}
	cp->pgno = pg;
	cp->indx = QAM_RECNO_INDEX(dbp, pg, *recnop);

	if (PGNO(cp->page) == 0) {
		if (F_ISSET(dbp, DB_AM_RDONLY)) {
			*exactp = 0;
			return (0);
		}
		PGNO(cp->page) = pg;
		TYPE(cp->page) = P_QAMDATA;
	}

	qp = QAM_GET_RECORD(dbp, cp->page, cp->indx);
	*exactp = F_ISSET(qp, QAM_VALID) ? 1 : 0;

	return (ret);
}

/*
 * __qam_pitem --
 *	Put an item on a queue page.  Copy the data to the page and set the
 *	VALID and SET bits.  If logging and the record was previously set,
 *	log that data, otherwise just log the new data.
 *
 *   pagep must be write locked
 *
 * PUBLIC: int __qam_pitem
 * PUBLIC:     __P((DBC *,  QPAGE *, u_int32_t, db_recno_t, DBT *));
 */
int
__qam_pitem(dbc, pagep, indx, recno, data)
	DBC *dbc;
	QPAGE *pagep;
	u_int32_t indx;
	db_recno_t recno;
	DBT *data;
{
	DB_ENV *dbenv;
	DB *dbp;
	DBT olddata, pdata, *datap;
	QAMDATA *qp;
	QUEUE *t;
	u_int8_t *dest, *p;
	int alloced, ret;

	dbp = dbc->dbp;
	dbenv = dbp->dbenv;
	t = (QUEUE *)dbp->q_internal;
	alloced = ret = 0;

	if (data->size > t->re_len)
		return (__db_rec_toobig(dbenv, data->size, t->re_len));
	qp = QAM_GET_RECORD(dbp, pagep, indx);

	p = qp->data;
	datap = data;
	if (F_ISSET(data, DB_DBT_PARTIAL)) {
		if (data->doff + data->dlen > t->re_len) {
			__db_err(dbenv,
		"%s: data offset plus length larger than record size of %lu",
			    "Record length error", (u_long)t->re_len);
			return (EINVAL);
		}

		if (data->size != data->dlen)
			return (__db_rec_repl(dbenv, data->size, data->dlen));

		if (data->size == t->re_len)
			goto no_partial;

		/*
		 * If we are logging, then we have to build the record
		 * first, otherwise, we can simply drop the change
		 * directly on the page.  After this clause, make
		 * sure that datap and p are set up correctly so that
		 * copying datap into p does the right thing.
		 *
		 * Note, I am changing this so that if the existing
		 * record is not valid, we create a complete record
		 * to log so that both this and the recovery code is simpler.
		 */

		if (DBC_LOGGING(dbc) || !F_ISSET(qp, QAM_VALID)) {
			datap = &pdata;
			memset(datap, 0, sizeof(*datap));

			if ((ret = __os_malloc(dbenv,
			    t->re_len, &datap->data)) != 0)
				return (ret);
			alloced = 1;
			datap->size = t->re_len;

			/*
			 * Construct the record if it's valid, otherwise set it
			 * all to the pad character.
			 */
			dest = datap->data;
			if (F_ISSET(qp, QAM_VALID))
				memcpy(dest, p, t->re_len);
			else
				memset(dest, t->re_pad, t->re_len);

			dest += data->doff;
			memcpy(dest, data->data, data->size);
		} else {
			datap = data;
			p += data->doff;
		}
	}

no_partial:
	if (DBC_LOGGING(dbc)) {
		olddata.size = 0;
		if (F_ISSET(qp, QAM_SET)) {
			olddata.data = qp->data;
			olddata.size = t->re_len;
		}
		if ((ret = __qam_add_log(dbp, dbc->txn, &LSN(pagep),
		    0, &LSN(pagep), pagep->pgno,
		    indx, recno, datap, qp->flags,
		    olddata.size == 0 ? NULL : &olddata)) != 0)
			goto err;
	}

	F_SET(qp, QAM_VALID | QAM_SET);
	memcpy(p, datap->data, datap->size);
	if (!F_ISSET(data, DB_DBT_PARTIAL))
		memset(p + datap->size,  t->re_pad, t->re_len - datap->size);

err:	if (alloced)
		__os_free(dbenv, datap->data);

	return (ret);
}
/*
 * __qam_c_put
 *	Cursor put for queued access method.
 *	BEFORE and AFTER cannot be specified.
 */
static int
__qam_c_put(dbc, key, data, flags, pgnop)
	DBC *dbc;
	DBT *key, *data;
	u_int32_t flags;
	db_pgno_t *pgnop;
{
	DB *dbp;
	DB_LOCK lock;
	DB_MPOOLFILE *mpf;
	QMETA *meta;
	QUEUE_CURSOR *cp;
	db_pgno_t pg;
	db_recno_t new_cur, new_first;
	u_int32_t opcode;
	int exact, ret, t_ret;

	dbp = dbc->dbp;
	mpf = dbp->mpf;
	if (pgnop != NULL)
		*pgnop = PGNO_INVALID;

	cp = (QUEUE_CURSOR *)dbc->internal;

	switch (flags) {
	case DB_KEYFIRST:
	case DB_KEYLAST:
		if ((ret = __qam_getno(dbp, key, &cp->recno)) != 0)
			return (ret);
		/* FALLTHROUGH */
	case DB_CURRENT:
		break;
	default:
		/* The interface shouldn't let anything else through. */
		DB_ASSERT(0);
		return (__db_ferr(dbp->dbenv, "__qam_c_put", flags));
	}

	/* Write lock the record. */
	if ((ret = __db_lget(dbc,
	    0, cp->recno, DB_LOCK_WRITE, DB_LOCK_RECORD, &lock)) != 0)
		return (ret);

	if ((ret = __qam_position(dbc,
	    &cp->recno, QAM_WRITE, &exact)) != 0) {
		/* We could not get the page, we can release the record lock. */
		__LPUT(dbc, lock);
		return (ret);
	}

	/* Put the item on the page. */
	ret = __qam_pitem(dbc, (QPAGE *)cp->page, cp->indx, cp->recno, data);

	/* Doing record locking, release the page lock */
	if ((t_ret = __LPUT(dbc, cp->lock)) != 0 && ret == 0)
		ret = t_ret;
	if ((t_ret = __qam_fput(
	    dbp, cp->pgno, cp->page, DB_MPOOL_DIRTY)) != 0 && ret == 0)
		ret = t_ret;
	cp->page = NULL;
	cp->lock = lock;
	cp->lock_mode = DB_LOCK_WRITE;
	if (ret != 0)
		return (ret);

	/* We may need to reset the head or tail of the queue. */
	pg = ((QUEUE *)dbp->q_internal)->q_meta;

	/*
	 * Get the meta page first, we don't want to write lock it while
	 * trying to pin it.
	 */
	if ((ret = __memp_fget(mpf, &pg, 0, &meta)) != 0)
		return (ret);
	if ((ret = __db_lget(dbc, 0, pg,  DB_LOCK_WRITE, 0, &lock)) != 0) {
		(void)__memp_fput(mpf, meta, 0);
		return (ret);
	}

	opcode = 0;
	new_cur = new_first = 0;

	/*
	 * If the put address is outside the queue, adjust the head and
	 * tail of the queue.  If the order is inverted we move
	 * the one which is closer.  The first case is when the
	 * queue is empty, move first and current to where the new
	 * insert is.
	 */

	if (meta->first_recno == meta->cur_recno) {
		new_first = cp->recno;
		new_cur = cp->recno + 1;
		if (new_cur == RECNO_OOB)
			new_cur++;
		opcode |= QAM_SETFIRST;
		opcode |= QAM_SETCUR;
	} else {
		if (QAM_BEFORE_FIRST(meta, cp->recno) &&
		    (meta->first_recno <= meta->cur_recno ||
		    meta->first_recno - cp->recno <
		    cp->recno - meta->cur_recno)) {
			new_first = cp->recno;
			opcode |= QAM_SETFIRST;
		}

		if (meta->cur_recno == cp->recno ||
		    (QAM_AFTER_CURRENT(meta, cp->recno) &&
		    (meta->first_recno <= meta->cur_recno ||
		    cp->recno - meta->cur_recno <=
		    meta->first_recno - cp->recno))) {
			new_cur = cp->recno + 1;
			if (new_cur == RECNO_OOB)
				new_cur++;
			opcode |= QAM_SETCUR;
		}
	}

	if (opcode != 0 && DBC_LOGGING(dbc)) {
		ret = __qam_mvptr_log(dbp, dbc->txn, &meta->dbmeta.lsn,
		    0, opcode, meta->first_recno, new_first,
		    meta->cur_recno, new_cur, &meta->dbmeta.lsn, PGNO_BASE_MD);
		if (ret != 0)
			opcode = 0;
	}

	if (opcode & QAM_SETCUR)
		meta->cur_recno = new_cur;
	if (opcode & QAM_SETFIRST)
		meta->first_recno = new_first;

	if ((t_ret = __memp_fput(
	    mpf, meta, opcode != 0 ? DB_MPOOL_DIRTY : 0)) != 0 && ret == 0)
		ret = t_ret;

	/* Don't hold the meta page long term. */
	if ((t_ret = __LPUT(dbc, lock)) != 0 && ret == 0)
		ret = t_ret;
	return (ret);
}

/*
 * __qam_append --
 *	Perform a put(DB_APPEND) in queue.
 *
 * PUBLIC: int __qam_append __P((DBC *, DBT *, DBT *));
 */
int
__qam_append(dbc, key, data)
	DBC *dbc;
	DBT *key, *data;
{
	DB *dbp;
	DB_LOCK lock;
	DB_MPOOLFILE *mpf;
	QMETA *meta;
	QPAGE *page;
	QUEUE *qp;
	QUEUE_CURSOR *cp;
	db_pgno_t pg;
	db_recno_t recno;
	int ret, t_ret;

	dbp = dbc->dbp;
	mpf = dbp->mpf;
	cp = (QUEUE_CURSOR *)dbc->internal;

	pg = ((QUEUE *)dbp->q_internal)->q_meta;
	/*
	 * Get the meta page first, we don't want to write lock it while
	 * trying to pin it.
	 */
	if ((ret = __memp_fget(mpf, &pg, 0, &meta)) != 0)
		return (ret);
	/* Write lock the meta page. */
	if ((ret = __db_lget(dbc, 0, pg,  DB_LOCK_WRITE, 0, &lock)) != 0) {
		(void)__memp_fput(mpf, meta, 0);
		return (ret);
	}

	/* Get the next record number. */
	recno = meta->cur_recno;
	meta->cur_recno++;
	if (meta->cur_recno == RECNO_OOB)
		meta->cur_recno++;
	if (meta->cur_recno == meta->first_recno) {
		meta->cur_recno--;
		if (meta->cur_recno == RECNO_OOB)
			meta->cur_recno--;
		(void)__LPUT(dbc, lock);
		ret = EFBIG;
		goto err;
	}

	if (QAM_BEFORE_FIRST(meta, recno))
		meta->first_recno = recno;

	/* Lock the record and release meta page lock. */
	ret = __db_lget(dbc, LCK_COUPLE_ALWAYS,
	    recno, DB_LOCK_WRITE, DB_LOCK_RECORD, &lock);

	/*
	 * The application may modify the data based on the selected record
	 * number.  We always want to call this even if we ultimately end
	 * up aborting, because we are allocating a record number, regardless.
	 */
	if (dbc->dbp->db_append_recno != NULL &&
	    (t_ret = dbc->dbp->db_append_recno(dbc->dbp, data, recno)) != 0 &&
	    ret == 0)
		ret = t_ret;

	/*
	 * Capture errors from either the lock couple or the call to
	 * dbp->db_append_recno.
	 */
	if (ret != 0) {
		(void)__LPUT(dbc, lock);
		goto err;
	}

	cp->lock = lock;
	cp->lock_mode = DB_LOCK_WRITE;

	pg = QAM_RECNO_PAGE(dbp, recno);

	/* Fetch and write lock the data page. */
	if ((ret = __db_lget(dbc, 0, pg,  DB_LOCK_WRITE, 0, &lock)) != 0)
		goto err;
	if ((ret = __qam_fget(dbp, &pg, DB_MPOOL_CREATE, &page)) != 0) {
		/* We did not fetch it, we can release the lock. */
		(void)__LPUT(dbc, lock);
		goto err;
	}

	/* See if this is a new page. */
	if (page->pgno == 0) {
		page->pgno = pg;
		page->type = P_QAMDATA;
	}

	/* Put the item on the page and log it. */
	ret = __qam_pitem(dbc, page,
	    QAM_RECNO_INDEX(dbp, pg, recno), recno, data);

	/* Doing record locking, release the page lock */
	if ((t_ret = __LPUT(dbc, lock)) != 0 && ret == 0)
		ret = t_ret;

	if ((t_ret
	    = __qam_fput(dbp, pg, page, DB_MPOOL_DIRTY)) != 0 && ret == 0)
		ret = t_ret;

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

	/* Position the cursor on this record. */
	cp->recno = recno;

	/* See if we are leaving the extent. */
	qp = (QUEUE *) dbp->q_internal;
	if (qp->page_ext != 0 &&
	    (recno % (qp->page_ext * qp->rec_page) == 0 ||
	    recno == UINT32_T_MAX)) {
		if ((ret = __db_lget(dbc,
		    0, ((QUEUE *)dbp->q_internal)->q_meta,
		    DB_LOCK_WRITE, 0, &lock)) != 0)
			goto err;
		if (!QAM_AFTER_CURRENT(meta, recno))
			ret = __qam_fclose(dbp, pg);
		(void)__LPUT(dbc, lock);
	}

err:
	/* Release the meta page. */
	if ((t_ret = __memp_fput(mpf, meta, DB_MPOOL_DIRTY)) != 0 && ret == 0)
		ret = t_ret;

	return (ret);
}

/*
 * __qam_c_del --
 *	Qam cursor->am_del function
 */
static int
__qam_c_del(dbc)
	DBC *dbc;
{
	DB *dbp;
	DBT data;
	DB_LOCK lock, metalock;
	DB_MPOOLFILE *mpf;
	PAGE *pagep;
	QAMDATA *qp;
	QMETA *meta;
	QUEUE_CURSOR *cp;
	db_pgno_t pg;
	db_recno_t first;
	int exact, ret, t_ret;

	dbp = dbc->dbp;
	mpf = dbp->mpf;
	cp = (QUEUE_CURSOR *)dbc->internal;

	pg = ((QUEUE *)dbp->q_internal)->q_meta;
	/*
	 * Get the meta page first, we don't want to write lock it while
	 * trying to pin it.
	 */
	if ((ret = __memp_fget(mpf, &pg, 0, &meta)) != 0)
		return (ret);
	/* Write lock the meta page. */
	if ((ret = __db_lget(dbc, 0, pg,  DB_LOCK_READ, 0, &metalock)) != 0) {
		(void)__memp_fput(mpf, meta, 0);
		return (ret);
	}

	if (QAM_NOT_VALID(meta, cp->recno))
		ret = DB_NOTFOUND;

	first = meta->first_recno;

	/* Don't hold the meta page long term. */
	if ((t_ret = __LPUT(dbc, metalock)) != 0 && ret == 0)
		ret = t_ret;

	if (ret != 0)
		goto err1;

	if ((ret = __db_lget(dbc,
	    0, cp->recno, DB_LOCK_WRITE, DB_LOCK_RECORD, &lock)) != 0)
		goto err1;

	cp->lock_mode = DB_LOCK_WRITE;
	/* Find the record ; delete only deletes exact matches. */
	if ((ret = __qam_position(dbc,
	    &cp->recno, QAM_WRITE, &exact)) != 0) {
		cp->lock = lock;
		goto err1;
	}
	if (!exact) {
		ret = DB_NOTFOUND;
		goto err1;
	}

	pagep = cp->page;
	qp = QAM_GET_RECORD(dbp, pagep, cp->indx);

	if (DBC_LOGGING(dbc)) {
		if (((QUEUE *)dbp->q_internal)->page_ext == 0 ||
		    ((QUEUE *)dbp->q_internal)->re_len == 0) {
			if ((ret = __qam_del_log(dbp,
			    dbc->txn, &LSN(pagep), 0, &LSN(pagep),
			    pagep->pgno, cp->indx, cp->recno)) != 0)
				goto err1;
		} else {
			data.size = ((QUEUE *)dbp->q_internal)->re_len;
			data.data = qp->data;
			if ((ret = __qam_delext_log(dbp,
			    dbc->txn, &LSN(pagep), 0, &LSN(pagep),
			    pagep->pgno, cp->indx, cp->recno, &data)) != 0)
				goto err1;
		}
	}

	F_CLR(qp, QAM_VALID);

	if (cp->recno == first) {
		pg = ((QUEUE *)dbp->q_internal)->q_meta;
		if ((ret =
		    __db_lget(dbc, 0, pg,  DB_LOCK_WRITE, 0, &metalock)) != 0)
			goto err1;
		ret = __qam_consume(dbc, meta, first);
		if ((t_ret = __LPUT(dbc, metalock)) != 0 && ret == 0)
			ret = t_ret;
	}

err1:
	if ((t_ret = __memp_fput(mpf, meta, 0)) != 0 && ret == 0)
		ret = t_ret;
	if (cp->page != NULL && (t_ret = __qam_fput(dbp, cp->pgno,
	    cp->page, ret == 0 ? DB_MPOOL_DIRTY : 0)) != 0 && ret == 0)
		ret = t_ret;
	cp->page = NULL;

	/* Doing record locking, release the page lock */
	if ((t_ret = __LPUT(dbc, cp->lock)) != 0 && ret == 0)
		ret = t_ret;
	cp->lock = lock;

	return (ret);
}

#ifdef	DEBUG_WOP
#define	QDEBUG
#endif

/*
 * __qam_c_get --
 *	Queue cursor->c_get function.
 */
static int
__qam_c_get(dbc, key, data, flags, pgnop)
	DBC *dbc;
	DBT *key, *data;
	u_int32_t flags;
	db_pgno_t *pgnop;
{
	DB *dbp;
	DBC *dbcdup;
	DBT tmp;
	DB_ENV *dbenv;
	DB_LOCK lock, pglock, metalock;
	DB_MPOOLFILE *mpf;
	PAGE *pg;
	QAMDATA *qp;
	QMETA *meta;
	QUEUE *t;
	QUEUE_CURSOR *cp;
	db_lockmode_t lock_mode;
	db_pgno_t metapno;
	db_recno_t first;
	qam_position_mode mode;
	int exact, is_first, locked, ret, t_ret, wait, with_delete;
	int put_mode, retrying;

	dbp = dbc->dbp;
	dbenv = dbp->dbenv;
	mpf = dbp->mpf;
	cp = (QUEUE_CURSOR *)dbc->internal;

	PANIC_CHECK(dbenv);

	wait = 0;
	with_delete = 0;
	retrying = 0;
	lock_mode = DB_LOCK_READ;
	meta = NULL;
	put_mode = 0;
	t_ret = 0;
	*pgnop = 0;
	pg = NULL;

	mode = QAM_READ;
	if (F_ISSET(dbc, DBC_RMW)) {
		lock_mode = DB_LOCK_WRITE;
		mode = QAM_WRITE;
	}

	if (flags == DB_CONSUME_WAIT) {
		wait = 1;
		flags = DB_CONSUME;
	}
	if (flags == DB_CONSUME) {
		with_delete = 1;
		flags = DB_FIRST;
		lock_mode = DB_LOCK_WRITE;
		mode = QAM_CONSUME;
	}

	DEBUG_LREAD(dbc, dbc->txn, "qam_c_get",
	    flags == DB_SET || flags == DB_SET_RANGE ? key : NULL, NULL, flags);

	/* Make lint and friends happy. */
	locked = 0;

	is_first = 0;

	t = (QUEUE *)dbp->q_internal;
	metapno = t->q_meta;

	/*
	 * Get the meta page first, we don't want to write lock it while
	 * trying to pin it.  This is because someone my have it pinned
	 * but not locked.
	 */
	if ((ret = __memp_fget(mpf, &metapno, 0, &meta)) != 0)
		return (ret);
	if ((ret = __db_lget(dbc, 0, metapno, lock_mode, 0, &metalock)) != 0)
		goto err;
	locked = 1;

	first = 0;

	/* Release any previous lock if not in a transaction. */
	(void)__TLPUT(dbc, cp->lock);

retry:	/* Update the record number. */
	switch (flags) {
	case DB_CURRENT:
		break;
	case DB_NEXT_DUP:
		ret = DB_NOTFOUND;
		goto err;
		/* NOTREACHED */
	case DB_NEXT:
	case DB_NEXT_NODUP:
		if (cp->recno != RECNO_OOB) {
			++cp->recno;
			/* Wrap around, skipping zero. */
			if (cp->recno == RECNO_OOB)
				cp->recno++;
			/*
			 * Check to see if we are out of data.
			 */
			if (cp->recno == meta->cur_recno ||
			    QAM_AFTER_CURRENT(meta, cp->recno)) {
				pg = NULL;
				if (!wait) {
					ret = DB_NOTFOUND;
					goto err;
				}
				flags = DB_FIRST;
				/*
				 * If first is not set, then we skipped
				 * a locked record, go back and find it.
				 * If we find a locked record again
				 * wait for it.
				 */
				if (first == 0) {
					retrying = 1;
					goto retry;
				}

				if (CDB_LOCKING(dbenv)) {
					/* Drop the metapage before we wait. */
					if ((ret =
					    __memp_fput(mpf, meta, 0)) != 0)
						goto err;
					meta = NULL;
					if ((ret = __lock_get(
					    dbenv, dbc->locker,
					    DB_LOCK_SWITCH, &dbc->lock_dbt,
					    DB_LOCK_WAIT, &dbc->mylock)) != 0)
						goto err;

					if ((ret = __memp_fget(mpf,
					     &metapno, 0, &meta)) != 0)
						goto err;
					if ((ret = __lock_get(
					    dbenv, dbc->locker,
					    DB_LOCK_UPGRADE, &dbc->lock_dbt,
					    DB_LOCK_WRITE, &dbc->mylock)) != 0)
						goto err;
					goto retry;
				}
				/*
				 * Wait for someone to update the meta page.
				 * This will probably mean there is something
				 * in the queue.  We then go back up and
				 * try again.
				 */
				if (locked == 0) {
					if ((ret = __db_lget(dbc, 0, metapno,
					     lock_mode, 0, &metalock)) != 0)
						goto err;
					locked = 1;
					if (cp->recno != RECNO_OOB &&
					    !QAM_AFTER_CURRENT(meta, cp->recno))
						goto retry;
				}
				/* Drop the metapage before we wait. */
				if ((ret = __memp_fput(mpf, meta, 0)) != 0)
					goto err;
				meta = NULL;
				if ((ret = __db_lget(dbc,
				     0, metapno, DB_LOCK_WAIT,
				     DB_LOCK_SWITCH, &metalock)) != 0) {
					if (ret == DB_LOCK_DEADLOCK)
						ret = DB_LOCK_NOTGRANTED;
					goto err;
				}
				if ((ret = __memp_fget(
				     mpf, &metapno, 0, &meta)) != 0)
					goto err;
				if ((ret = __lock_get(dbenv,
				      dbc->locker, DB_LOCK_UPGRADE,
				      &dbc->lock_dbt, DB_LOCK_WRITE,
				      &metalock)) != 0)
					goto err;
				locked = 1;
				goto retry;
			}
			break;
		}
		/* FALLTHROUGH */
	case DB_FIRST:
		flags = DB_NEXT;
		is_first = 1;

		/* get the first record number */
		cp->recno = first = meta->first_recno;

		break;
	case DB_PREV:
	case DB_PREV_NODUP:
		if (cp->recno != RECNO_OOB) {
			if (cp->recno == meta->first_recno ||
			   QAM_BEFORE_FIRST(meta, cp->recno)) {
				ret = DB_NOTFOUND;
				goto err;
			}
			--cp->recno;
			/* Wrap around, skipping zero. */
			if (cp->recno == RECNO_OOB)
				--cp->recno;
			break;
		}
		/* FALLTHROUGH */
	case DB_LAST:
		if (meta->first_recno == meta->cur_recno) {
			ret = DB_NOTFOUND;
			goto err;
		}
		cp->recno = meta->cur_recno - 1;
		if (cp->recno == RECNO_OOB)
			cp->recno--;
		break;
	case DB_SET:
	case DB_SET_RANGE:
	case DB_GET_BOTH:
	case DB_GET_BOTH_RANGE:
		if ((ret = __qam_getno(dbp,
		    key, &cp->recno)) != 0)
			goto err;
		if (QAM_NOT_VALID(meta, cp->recno)) {
			ret = DB_NOTFOUND;
			goto err;
		}
		break;
	default:
		ret = __db_unknown_flag(dbenv, "__qam_c_get", flags);
		goto err;
	}

	/* Don't hold the meta page long term. */
	if (locked) {
		if ((ret = __LPUT(dbc, metalock)) != 0)
			goto err;
		locked = 0;
	}

	/* Lock the record. */
	if ((ret = __db_lget(dbc, 0, cp->recno, lock_mode,
	    (with_delete && !retrying) ?
	    DB_LOCK_NOWAIT | DB_LOCK_RECORD : DB_LOCK_RECORD,
	    &lock)) == DB_LOCK_DEADLOCK && with_delete) {
#ifdef QDEBUG
		__db_logmsg(dbenv,
		    dbc->txn, "Queue S", 0, "%x %d %d %d",
		    dbc->locker, cp->recno, first, meta->first_recno);
#endif
		first = 0;
		if ((ret =
		    __db_lget(dbc, 0, metapno, lock_mode, 0, &metalock)) != 0)
			goto err;
		locked = 1;
		goto retry;
	}

	if (ret != 0)
		goto err;

	/*
	 * In the DB_FIRST or DB_LAST cases we must wait and then start over
	 * since the first/last may have moved while we slept.
	 * We release our locks and try again.
	 */
	if ((!with_delete && is_first) || flags == DB_LAST) {
		if ((ret =
		    __db_lget(dbc, 0, metapno, lock_mode, 0, &metalock)) != 0)
			goto err;
		if (cp->recno !=
		    (is_first ? meta->first_recno : (meta->cur_recno - 1))) {
			__LPUT(dbc, lock);
			if (is_first)
				flags = DB_FIRST;
			locked = 1;
			goto retry;
		}
		/* Don't hold the meta page long term. */
		if ((ret = __LPUT(dbc, metalock)) != 0)
			goto err;
	}

	/* Position the cursor on the record. */
	if ((ret = __qam_position(dbc, &cp->recno, mode, &exact)) != 0) {
		/* We cannot get the page, release the record lock. */
		(void)__LPUT(dbc, lock);
		goto err;
	}

	pg = cp->page;
	pglock = cp->lock;
	cp->lock = lock;
	cp->lock_mode = lock_mode;

	if (!exact) {
		if (flags == DB_NEXT || flags == DB_NEXT_NODUP ||
		    flags == DB_PREV || flags == DB_PREV_NODUP ||
		    flags == DB_LAST) {
			/* Release locks and try again. */
			if (pg != NULL)
				(void)__qam_fput(dbp, cp->pgno, pg, 0);
			cp->page = pg = NULL;
			(void)__LPUT(dbc, pglock);
			(void)__LPUT(dbc, cp->lock);
			if (flags == DB_LAST)
				flags = DB_PREV;
			if (!with_delete)
				is_first = 0;
			retrying = 0;
			goto retry;
		}
		/* this is for the SET and SET_RANGE cases */
		ret = DB_KEYEMPTY;
		goto err1;
	}

	/* Return the key if the user didn't give us one. */
	if (key != NULL) {
		if (flags != DB_GET_BOTH && flags != DB_GET_BOTH_RANGE &&
		    flags != DB_SET && flags != DB_SET_RANGE &&
		    (ret = __db_retcopy(dbp->dbenv,
		    key, &cp->recno, sizeof(cp->recno),
		    &dbc->rkey->data, &dbc->rkey->ulen)) != 0)
			goto err1;
		F_SET(key, DB_DBT_ISSET);
	}

	qp = QAM_GET_RECORD(dbp, pg, cp->indx);

	/* Return the data item. */
	if (flags == DB_GET_BOTH || flags == DB_GET_BOTH_RANGE) {
		/*
		 * Need to compare
		 */
		tmp.data = qp->data;
		tmp.size = t->re_len;
		if ((ret = __bam_defcmp(dbp, data, &tmp)) != 0) {
			ret = DB_NOTFOUND;
			goto err1;
		}
	}
	if (data != NULL &&
	    !F_ISSET(dbc, DBC_MULTIPLE|DBC_MULTIPLE_KEY) &&
	    (ret = __db_retcopy(dbp->dbenv, data,
	    qp->data, t->re_len, &dbc->rdata->data, &dbc->rdata->ulen)) != 0)
		goto err1;

	if (data != NULL)
		F_SET(data, DB_DBT_ISSET);

	/* Finally, if we are doing DB_CONSUME mark the record. */
	if (with_delete) {
		/*
		 * Assert that we're not a secondary index.  Doing a DB_CONSUME
		 * on a secondary makes very little sense, since one can't
		 * DB_APPEND there;  attempting one should be forbidden by
		 * the interface.
		 */
		DB_ASSERT(!F_ISSET(dbp, DB_AM_SECONDARY));

		/*
		 * Check and see if we *have* any secondary indices.
		 * If we do, we're a primary, so call __db_c_del_primary
		 * to delete the references to the item we're about to
		 * delete.
		 *
		 * Note that we work on a duplicated cursor, since the
		 * __db_ret work has already been done, so it's not safe
		 * to perform any additional ops on this cursor.
		 */
		if (LIST_FIRST(&dbp->s_secondaries) != NULL) {
			if ((ret = __db_c_idup(dbc,
			    &dbcdup, DB_POSITION)) != 0)
				goto err1;

			if ((ret = __db_c_del_primary(dbcdup)) != 0) {
				/*
				 * The __db_c_del_primary return is more
				 * interesting.
				 */
				(void)__db_c_close(dbcdup);
				goto err1;
			}

			if ((ret = __db_c_close(dbcdup)) != 0)
				goto err1;
		}

		if (DBC_LOGGING(dbc)) {
			if (t->page_ext == 0 || t->re_len == 0) {
				if ((ret = __qam_del_log(dbp, dbc->txn,
				    &LSN(pg), 0, &LSN(pg),
				    pg->pgno, cp->indx, cp->recno)) != 0)
					goto err1;
			} else {
				tmp.data = qp->data;
				tmp.size = t->re_len;
				if ((ret = __qam_delext_log(dbp,
				   dbc->txn, &LSN(pg), 0, &LSN(pg),
				   pg->pgno, cp->indx, cp->recno, &tmp)) != 0)
					goto err1;
			}
		}

		F_CLR(qp, QAM_VALID);
		put_mode = DB_MPOOL_DIRTY;

		if ((ret = __LPUT(dbc, pglock)) != 0)
			goto err1;

		/*
		 * Now we need to update the metapage
		 * first pointer. If we have deleted
		 * the record that is pointed to by
		 * first_recno then we move it as far
		 * forward as we can without blocking.
		 * The metapage lock must be held for
		 * the whole scan otherwise someone could
		 * do a random insert behind where we are
		 * looking.
		 */

		if (locked == 0 && (ret = __db_lget(
		    dbc, 0, metapno, lock_mode, 0, &metalock)) != 0)
			goto err1;
		locked = 1;

#ifdef QDEBUG
		__db_logmsg(dbenv,
		    dbc->txn, "Queue D", 0, "%x %d %d %d",
		    dbc->locker, cp->recno, first, meta->first_recno);
#endif
		/*
		 * See if we deleted the "first" record.  If
		 * first is zero then we skipped something,
		 * see if first_recno has been move passed
		 * that to the record that we deleted.
		 */
		if (first == 0)
			first = cp->recno;
		if (first != meta->first_recno)
			goto done;

		if ((ret = __qam_consume(dbc, meta, first)) != 0)
			goto err1;
	}

done:
err1:	if (cp->page != NULL) {
		t_ret = __qam_fput(dbp, cp->pgno, cp->page, put_mode);

		if (!ret)
			ret = t_ret;
		/* Doing record locking, release the page lock */
		t_ret = __LPUT(dbc, pglock);
		cp->page = NULL;
	}

err:	if (!ret)
		ret = t_ret;
	if (meta) {

		/* release the meta page */
		t_ret = __memp_fput(mpf, meta, 0);

		if (!ret)
			ret = t_ret;

		/* Don't hold the meta page long term. */
		if (locked)
			t_ret = __LPUT(dbc, metalock);
	}
	DB_ASSERT(!LOCK_ISSET(metalock));

	/*
	 * There is no need to keep the record locked if we are
	 * not in a transaction.
	 */
	if (t_ret == 0)
		t_ret = __TLPUT(dbc, cp->lock);

	if (!ret)
		ret = t_ret;

	return ((ret == DB_LOCK_NOTGRANTED &&
	     !F_ISSET(dbenv, DB_ENV_TIME_NOTGRANTED)) ?
	     DB_LOCK_DEADLOCK : ret);
}

/*
 * __qam_consume -- try to reset the head of the queue.
 *
 */

static int
__qam_consume(dbc, meta, first)
	DBC *dbc;
	QMETA *meta;
	db_recno_t first;
{
	DB *dbp;
	DB_LOCK lock, save_lock;
	DB_MPOOLFILE *mpf;
	QUEUE_CURSOR *cp;
	db_indx_t save_indx;
	db_pgno_t save_page;
	db_recno_t current, save_recno;
	u_int32_t rec_extent;
	int exact, put_mode, ret, t_ret, wrapped;

	dbp = dbc->dbp;
	mpf = dbp->mpf;
	cp = (QUEUE_CURSOR *)dbc->internal;
	put_mode = DB_MPOOL_DIRTY;
	ret = t_ret = 0;

	save_page = cp->pgno;
	save_indx = cp->indx;
	save_recno = cp->recno;
	save_lock = cp->lock;

	/*
	 * If we skipped some deleted records, we need to
	 * reposition on the first one.  Get a lock
	 * in case someone is trying to put it back.
	 */
	if (first != cp->recno) {
		ret = __db_lget(dbc, 0, first, DB_LOCK_READ,
		    DB_LOCK_NOWAIT | DB_LOCK_RECORD, &lock);
		if (ret == DB_LOCK_DEADLOCK) {
			ret = 0;
			goto done;
		}
		if (ret != 0)
			goto done;
		if ((ret =
		    __qam_fput(dbp, cp->pgno, cp->page, put_mode)) != 0)
			goto done;
		cp->page = NULL;
		put_mode = 0;
		if ((ret = __qam_position(dbc,
		    &first, QAM_READ, &exact)) != 0 || exact != 0) {
			(void)__LPUT(dbc, lock);
			goto done;
		}
		if ((ret =__LPUT(dbc, lock)) != 0)
			goto done;
		if ((ret = __LPUT(dbc, cp->lock)) != 0)
			goto done;
	}

	current = meta->cur_recno;
	wrapped = 0;
	if (first > current)
		wrapped = 1;
	rec_extent = meta->page_ext * meta->rec_page;

	/* Loop until we find a record or hit current */
	for (;;) {
		/*
		 * Check to see if we are moving off the extent
		 * and remove the extent.
		 * If we are moving off a page we need to
		 * get rid of the buffer.
		 * Wait for the lagging readers to move off the
		 * page.
		 */
		if (cp->page != NULL && rec_extent != 0 &&
		    ((exact = (first % rec_extent == 0)) ||
		    first % meta->rec_page == 0 ||
		    first == UINT32_T_MAX)) {
			if (exact == 1 && (ret = __db_lget(dbc,
			    0, cp->pgno, DB_LOCK_WRITE, 0, &cp->lock)) != 0)
				break;

#ifdef QDEBUG
			__db_logmsg(dbp->dbenv,
			    dbc->txn, "Queue R", 0, "%x %d %d %d",
			    dbc->locker, cp->pgno, first, meta->first_recno);
#endif
			put_mode |= DB_MPOOL_DISCARD;
			if ((ret = __qam_fput(dbp,
			    cp->pgno, cp->page, put_mode)) != 0)
				break;
			cp->page = NULL;

			if (exact == 1) {
				ret = __qam_fremove(dbp, cp->pgno);
				t_ret = __LPUT(dbc, cp->lock);
			}
			if (ret != 0)
				break;
			if (t_ret != 0) {
				ret = t_ret;
				break;
			}
		} else if (cp->page != NULL && (ret =
		    __qam_fput(dbp, cp->pgno, cp->page, put_mode)) != 0)
			break;
		cp->page = NULL;
		first++;
		if (first == RECNO_OOB) {
			wrapped = 0;
			first++;
		}

		/*
		 * LOOP EXIT when we come move to the current
		 * pointer.
		 */
		if (!wrapped && first >= current)
			break;

		ret = __db_lget(dbc, 0, first, DB_LOCK_READ,
		    DB_LOCK_NOWAIT | DB_LOCK_RECORD, &lock);
		if (ret == DB_LOCK_DEADLOCK) {
			ret = 0;
			break;
		}
		if (ret != 0)
			break;

		if ((ret = __qam_position(dbc,
		    &first, QAM_READ, &exact)) != 0) {
			(void)__LPUT(dbc, lock);
			break;
		}
		put_mode = 0;
		if ((ret =__LPUT(dbc, lock)) != 0 ||
		    (ret = __LPUT(dbc, cp->lock)) != 0 || exact) {
			if ((t_ret = __qam_fput(dbp, cp->pgno,
			    cp->page, put_mode)) != 0 && ret == 0)
				ret = t_ret;
			cp->page = NULL;
			break;
		}
	}

	cp->pgno = save_page;
	cp->indx = save_indx;
	cp->recno = save_recno;
	cp->lock = save_lock;

	/*
	 * We have advanced as far as we can.
	 * Advance first_recno to this point.
	 */
	if (ret == 0 && meta->first_recno != first) {
#ifdef QDEBUG
		__db_logmsg(dbp->dbenv, dbc->txn, "Queue M",
		    0, "%x %d %d %d", dbc->locker, cp->recno,
		    first, meta->first_recno);
#endif
		if (DBC_LOGGING(dbc))
			if ((ret = __qam_incfirst_log(dbp,
			    dbc->txn, &meta->dbmeta.lsn, 0,
			    cp->recno, PGNO_BASE_MD)) != 0)
				goto done;
		meta->first_recno = first;
		(void)__memp_fset(mpf, meta, DB_MPOOL_DIRTY);
	}

done:
	return (ret);
}

static int
__qam_bulk(dbc, data, flags)
	DBC *dbc;
	DBT *data;
	u_int32_t flags;
{
	DB *dbp;
	DB_LOCK metalock;
	DB_MPOOLFILE *mpf;
	PAGE *pg;
	QMETA *meta;
	QAMDATA *qp;
	QUEUE_CURSOR *cp;
	db_indx_t indx;
	db_pgno_t metapno;
	qam_position_mode mode;
	int32_t  *endp, *offp;
	u_int8_t *dbuf, *dp, *np;
	int exact, recs, re_len, ret, t_ret, valid;
	int is_key, need_pg, pagesize, size, space;

	dbp = dbc->dbp;
	mpf = dbp->mpf;
	cp = (QUEUE_CURSOR *)dbc->internal;

	mode = QAM_READ;
	if (F_ISSET(dbc, DBC_RMW))
		mode = QAM_WRITE;

	pagesize = dbp->pgsize;
	re_len = ((QUEUE *)dbp->q_internal)->re_len;
	recs = ((QUEUE *)dbp->q_internal)->rec_page;
	metapno = ((QUEUE *)dbp->q_internal)->q_meta;

	is_key = LF_ISSET(DB_MULTIPLE_KEY) ? 1 : 0;
	size = 0;

	if ((ret = __db_lget(dbc, 0, metapno, DB_LOCK_READ, 0, &metalock)) != 0)
		return (ret);
	if ((ret = __memp_fget(mpf, &metapno, 0, &meta)) != 0) {
		/* We did not fetch it, we can release the lock. */
		(void)__LPUT(dbc, metalock);
		return (ret);
	}

	dbuf = data->data;
	np = dp = dbuf;

	/* Keep track of space that is left.  There is an termination entry */
	space = data->ulen;
	space -= sizeof(*offp);

	/* Build the offset/size table form the end up. */
	endp = (int32_t *) ((u_int8_t *)dbuf + data->ulen);
	endp--;
	offp = endp;

next_pg:
	/* Wrap around, skipping zero. */
	if (cp->recno == RECNO_OOB)
		cp->recno++;
	if ((ret = __qam_position(dbc, &cp->recno, mode, &exact)) != 0)
		goto done;

	pg = cp->page;
	indx = cp->indx;
	need_pg = 1;

	do {
		/*
		 * If this page is a nonexistent page at the end of an
		 * extent, pg may be NULL.  A NULL page has no valid records,
		 * so just keep looping as though qp exists and isn't QAM_VALID;
		 * calling QAM_GET_RECORD is unsafe.
		 */
		valid = 0;

		if (pg != NULL) {
			qp = QAM_GET_RECORD(dbp, pg, indx);
			if (F_ISSET(qp, QAM_VALID)) {
				valid = 1;
				space -= (is_key ? 3 : 2) * sizeof(*offp);
				if (space < 0)
					goto get_space;
				if (need_pg) {
					dp = np;
					size = pagesize - QPAGE_SZ(dbp);
					if (space < size) {
get_space:
						if (offp == endp) {
							data->size =
							    ALIGN(size +
							    pagesize,
							    sizeof(u_int32_t));
							ret = ENOMEM;
							break;
						}
						if (indx != 0)
							indx--;
						cp->recno--;
						space = 0;
						break;
					}
					memcpy(dp,
					    (char *)pg + QPAGE_SZ(dbp), size);
					need_pg = 0;
					space -= size;
					np += size;
				}
				if (is_key)
					*offp-- = cp->recno;
				*offp-- = (int32_t)((u_int8_t*)qp -
				    (u_int8_t*)pg - QPAGE_SZ(dbp) +
				    dp - dbuf + SSZA(QAMDATA, data));
				*offp-- = re_len;
			}
		}
		if (!valid && is_key == 0) {
			*offp-- = 0;
			*offp-- = 0;
		}
		cp->recno++;
	} while (++indx < recs && cp->recno != RECNO_OOB &&
	    cp->recno != meta->cur_recno &&
	    !QAM_AFTER_CURRENT(meta, cp->recno));

	if ((t_ret = __TLPUT(dbc, cp->lock)) != 0 && ret == 0)
		ret = t_ret;

	if (cp->page != NULL) {
		if ((t_ret =
		    __qam_fput(dbp, cp->pgno, cp->page, 0)) != 0 && ret == 0)
			ret = t_ret;
		cp->page = NULL;
	}

	if (ret == 0 && space > 0 &&
	    (indx >= recs || cp->recno == RECNO_OOB) &&
	    cp->recno != meta->cur_recno &&
	    !QAM_AFTER_CURRENT(meta, cp->recno))
		goto next_pg;

	/*
	 * Correct recno in two cases:
	 * 1) If we just wrapped fetch must start at record 1 not a FIRST.
	 * 2) We ran out of space exactly at the end of a page.
	 */
	if (cp->recno == RECNO_OOB || (space == 0 && indx == recs))
		cp->recno--;

	if (is_key == 1)
		*offp = RECNO_OOB;
	else
		*offp = -1;

done:
	/* release the meta page */
	t_ret = __memp_fput(mpf, meta, 0);

	if (!ret)
		ret = t_ret;

	t_ret = __LPUT(dbc, metalock);

	return (ret);
}

/*
 * __qam_c_close --
 *	Close down the cursor from a single use.
 */
static int
__qam_c_close(dbc, root_pgno, rmroot)
	DBC *dbc;
	db_pgno_t root_pgno;
	int *rmroot;
{
	QUEUE_CURSOR *cp;

	COMPQUIET(root_pgno, 0);
	COMPQUIET(rmroot, NULL);

	cp = (QUEUE_CURSOR *)dbc->internal;

	/* Discard any locks not acquired inside of a transaction. */
	(void)__TLPUT(dbc, cp->lock);
	LOCK_INIT(cp->lock);

	cp->page = NULL;
	cp->pgno = PGNO_INVALID;
	cp->indx = 0;
	cp->lock_mode = DB_LOCK_NG;
	cp->recno = RECNO_OOB;
	cp->flags = 0;

	return (0);
}

/*
 * __qam_c_dup --
 *	Duplicate a queue cursor, such that the new one holds appropriate
 *	locks for the position of the original.
 *
 * PUBLIC: int __qam_c_dup __P((DBC *, DBC *));
 */
int
__qam_c_dup(orig_dbc, new_dbc)
	DBC *orig_dbc, *new_dbc;
{
	QUEUE_CURSOR *orig, *new;

	orig = (QUEUE_CURSOR *)orig_dbc->internal;
	new = (QUEUE_CURSOR *)new_dbc->internal;

	new->recno = orig->recno;

	/* reget the long term lock if we are not in a xact */
	if (orig_dbc->txn != NULL ||
	    !STD_LOCKING(orig_dbc) || !LOCK_ISSET(orig->lock))
		return (0);

	return (__db_lget(new_dbc,
	    0, new->recno, new->lock_mode, DB_LOCK_RECORD, &new->lock));
}

/*
 * __qam_c_init
 *
 * PUBLIC: int __qam_c_init __P((DBC *));
 */
int
__qam_c_init(dbc)
	DBC *dbc;
{
	QUEUE_CURSOR *cp;
	DB *dbp;
	int ret;

	dbp = dbc->dbp;

	/* Allocate the internal structure. */
	cp = (QUEUE_CURSOR *)dbc->internal;
	if (cp == NULL) {
		if ((ret =
		    __os_calloc(dbp->dbenv, 1, sizeof(QUEUE_CURSOR), &cp)) != 0)
			return (ret);
		dbc->internal = (DBC_INTERNAL *)cp;
	}

	/* Initialize methods. */
	dbc->c_close = __db_c_close;
	dbc->c_count = __db_c_count_pp;
	dbc->c_del = __db_c_del_pp;
	dbc->c_dup = __db_c_dup_pp;
	dbc->c_get = __db_c_get_pp;
	dbc->c_pget = __db_c_pget_pp;
	dbc->c_put = __db_c_put_pp;
	dbc->c_am_bulk = __qam_bulk;
	dbc->c_am_close = __qam_c_close;
	dbc->c_am_del = __qam_c_del;
	dbc->c_am_destroy = __qam_c_destroy;
	dbc->c_am_get = __qam_c_get;
	dbc->c_am_put = __qam_c_put;
	dbc->c_am_writelock = NULL;

	return (0);
}

/*
 * __qam_c_destroy --
 *	Close a single cursor -- internal version.
 */
static int
__qam_c_destroy(dbc)
	DBC *dbc;
{
	/* Discard the structures. */
	__os_free(dbc->dbp->dbenv, dbc->internal);

	return (0);
}

/*
 * __qam_getno --
 *	Check the user's record number.
 */
static int
__qam_getno(dbp, key, rep)
	DB *dbp;
	const DBT *key;
	db_recno_t *rep;
{
	if ((*rep = *(db_recno_t *)key->data) == 0) {
		__db_err(dbp->dbenv, "illegal record number of 0");
		return (EINVAL);
	}
	return (0);
}

/*
 * __qam_truncate --
 *	Truncate a queue database
 *
 * PUBLIC: int __qam_truncate __P((DBC *, u_int32_t *));
 */
int
__qam_truncate(dbc, countp)
	DBC *dbc;
	u_int32_t *countp;
{
	DB *dbp;
	DB_LOCK metalock;
	DB_MPOOLFILE *mpf;
	QMETA *meta;
	QUEUE_CURSOR *cp;
	db_pgno_t metapno;
	int count, ret, t_ret;

	dbp = dbc->dbp;

	/* Walk the queue, counting rows. */
	count = 0;
	while ((ret = __qam_c_get(dbc, NULL, NULL, DB_CONSUME, &metapno)) == 0)
		count++;

	if (ret == DB_NOTFOUND)
		ret = 0;
	else
		return (ret);

	cp = (QUEUE_CURSOR *)dbc->internal;
	/* Remove the last extent file. */
	if (cp->pgno != 0 &&
	    ((QUEUE *)dbp->q_internal)->page_ext != 0 && 
	    (ret = __qam_fremove(dbp, cp->pgno)) != 0)
		return (ret);

	/* Update the meta page. */
	metapno = ((QUEUE *)dbp->q_internal)->q_meta;
	if ((ret =
	    __db_lget(dbc, 0, metapno, DB_LOCK_WRITE, 0, &metalock)) != 0)
		return (ret);

	mpf = dbp->mpf;
	if ((ret = __memp_fget(mpf, &metapno, 0, &meta)) != 0) {
		/* We did not fetch it, we can release the lock. */
		(void)__LPUT(dbc, metalock);
		return (ret);
	}
	if (DBC_LOGGING(dbc)) {
		ret = __qam_mvptr_log(dbp, dbc->txn, &meta->dbmeta.lsn, 0,
		    QAM_SETCUR | QAM_SETFIRST | QAM_TRUNCATE, meta->first_recno,
		    1, meta->cur_recno, 1, &meta->dbmeta.lsn, PGNO_BASE_MD);
	}
	if (ret == 0)
		meta->first_recno = meta->cur_recno = 1;

	if ((t_ret = __memp_fput(mpf,
	    meta, ret == 0 ? DB_MPOOL_DIRTY: 0)) != 0 && ret == 0)
		ret = t_ret;
	if ((t_ret = __LPUT(dbc, metalock)) != 0 && ret == 0)
		ret = t_ret;

	*countp = count;

	return (ret);
}