lock.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) 1996-2002
 *	Sleepycat Software.  All rights reserved.
 */

#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: lock.c,v 11.108 2002/08/06 06:11:34 bostic Exp $";
#endif /* not lint */

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

#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/db_shash.h"
#include "dbinc/lock.h"
#include "dbinc/log.h"
#include "dbinc/txn.h"

static int  __lock_checklocker __P((DB_LOCKTAB *,
		struct __db_lock *, u_int32_t, u_int32_t));
static void __lock_expires __P((DB_ENV *, db_timeval_t *, db_timeout_t));
static void __lock_freelocker
		__P((DB_LOCKTAB *, DB_LOCKREGION *, DB_LOCKER *, u_int32_t));
static int  __lock_get_internal __P((DB_LOCKTAB *, u_int32_t, u_int32_t,
		const DBT *, db_lockmode_t, db_timeout_t, DB_LOCK *));
static int  __lock_getobj
		__P((DB_LOCKTAB *, const DBT *, u_int32_t, int, DB_LOCKOBJ **));
static int  __lock_is_parent __P((DB_LOCKTAB *, u_int32_t, DB_LOCKER *));
static int  __lock_put_internal __P((DB_LOCKTAB *,
		struct __db_lock *, u_int32_t,  u_int32_t));
static int  __lock_put_nolock __P((DB_ENV *, DB_LOCK *, int *, u_int32_t));
static void __lock_remove_waiter __P((DB_LOCKTAB *,
		DB_LOCKOBJ *, struct __db_lock *, db_status_t));
static int __lock_trade __P((DB_ENV *, DB_LOCK *, u_int32_t));

static const char __db_lock_err[] = "Lock table is out of available %s";
static const char __db_lock_invalid[] = "%s: Lock is no longer valid";
static const char __db_locker_invalid[] = "Locker is not valid";

/*
 * __lock_id --
 *	Generate a unique locker id.
 *
 * PUBLIC: int __lock_id __P((DB_ENV *, u_int32_t *));
 */
int
__lock_id(dbenv, idp)
	DB_ENV *dbenv;
	u_int32_t *idp;
{
	DB_LOCKER *lk;
	DB_LOCKTAB *lt;
	DB_LOCKREGION *region;
	u_int32_t *ids, locker_ndx;
	int nids, ret;

	PANIC_CHECK(dbenv);
	ENV_REQUIRES_CONFIG(dbenv,
	    dbenv->lk_handle, "DB_ENV->lock_id", DB_INIT_LOCK);

	lt = dbenv->lk_handle;
	region = lt->reginfo.primary;
	ret = 0;

	/*
	 * Allocate a new lock id.  If we wrap around then we
	 * find the minimum currently in use and make sure we
	 * can stay below that.  This code is similar to code
	 * in __txn_begin_int for recovering txn ids.
	 */
	LOCKREGION(dbenv, lt);
	/*
	 * Our current valid range can span the maximum valid value, so check
	 * for it and wrap manually.
	 */
	if (region->stat.st_id == DB_LOCK_MAXID &&
	    region->stat.st_cur_maxid != DB_LOCK_MAXID)
		region->stat.st_id = DB_LOCK_INVALIDID;
	if (region->stat.st_id == region->stat.st_cur_maxid) {
		if ((ret = __os_malloc(dbenv,
		    sizeof(u_int32_t) * region->stat.st_nlockers, &ids)) != 0)
			goto err;
		nids = 0;
		for (lk = SH_TAILQ_FIRST(&region->lockers, __db_locker);
		    lk != NULL;
		    lk = SH_TAILQ_NEXT(lk, ulinks, __db_locker))
			ids[nids++] = lk->id;
		region->stat.st_id = DB_LOCK_INVALIDID;
		region->stat.st_cur_maxid = DB_LOCK_MAXID;
		if (nids != 0)
			__db_idspace(ids, nids,
			    &region->stat.st_id, &region->stat.st_cur_maxid);
		__os_free(dbenv, ids);
	}
	*idp = ++region->stat.st_id;

	/* Allocate a locker for this id. */
	LOCKER_LOCK(lt, region, *idp, locker_ndx);
	ret = __lock_getlocker(lt, *idp, locker_ndx, 1, &lk);

err:	UNLOCKREGION(dbenv, lt);

	return (ret);
}

/*
 * __lock_id_free --
 *	Free a locker id.
 *
 * PUBLIC: int __lock_id_free __P((DB_ENV *, u_int32_t));
 */
int
__lock_id_free(dbenv, id)
	DB_ENV *dbenv;
	u_int32_t id;
{
	DB_LOCKER *sh_locker;
	DB_LOCKTAB *lt;
	DB_LOCKREGION *region;
	u_int32_t locker_ndx;
	int ret;

	PANIC_CHECK(dbenv);
	ENV_REQUIRES_CONFIG(dbenv,
	    dbenv->lk_handle, "DB_ENV->lock_id_free", DB_INIT_LOCK);

	lt = dbenv->lk_handle;
	region = lt->reginfo.primary;

	LOCKREGION(dbenv, lt);
	LOCKER_LOCK(lt, region, id, locker_ndx);
	if ((ret =
	    __lock_getlocker(lt, id, locker_ndx, 0, &sh_locker)) != 0)
		goto err;
	if (sh_locker == NULL) {
		ret = EINVAL;
		goto err;
	}

	if (sh_locker->nlocks != 0) {
		__db_err(dbenv, "Locker still has locks");
		ret = EINVAL;
		goto err;
	}

	__lock_freelocker(lt, region, sh_locker, locker_ndx);

err:	UNLOCKREGION(dbenv, lt);
	return (ret);
}

/*
 * __lock_vec --
 *	Vector lock routine.  This function takes a set of operations
 *	and performs them all at once.  In addition, lock_vec provides
 *	functionality for lock inheritance, releasing all locks for a
 *	given locker (used during transaction commit/abort), releasing
 *	all locks on a given object, and generating debugging information.
 *
 * PUBLIC: int __lock_vec __P((DB_ENV *,
 * PUBLIC:     u_int32_t, u_int32_t, DB_LOCKREQ *, int, DB_LOCKREQ **));
 */
int
__lock_vec(dbenv, locker, flags, list, nlist, elistp)
	DB_ENV *dbenv;
	u_int32_t locker, flags;
	int nlist;
	DB_LOCKREQ *list, **elistp;
{
	struct __db_lock *lp, *next_lock;
	DB_LOCK lock;
	DB_LOCKER *sh_locker, *sh_parent;
	DB_LOCKOBJ *obj, *sh_obj;
	DB_LOCKREGION *region;
	DB_LOCKTAB *lt;
	u_int32_t lndx, ndx;
	int did_abort, i, ret, run_dd, upgrade, writes;

	PANIC_CHECK(dbenv);
	ENV_REQUIRES_CONFIG(dbenv,
	    dbenv->lk_handle, "DB_ENV->lock_vec", DB_INIT_LOCK);

	/* Check if locks have been globally turned off. */
	if (F_ISSET(dbenv, DB_ENV_NOLOCKING))
		return (0);

	/* Validate arguments. */
	if ((ret = __db_fchk(dbenv, "DB_ENV->lock_vec",
	    flags, DB_LOCK_FREE_LOCKER | DB_LOCK_NOWAIT)) != 0)
		return (ret);

	lt = dbenv->lk_handle;
	region = lt->reginfo.primary;

	run_dd = 0;
	LOCKREGION(dbenv, (DB_LOCKTAB *)dbenv->lk_handle);
	for (i = 0, ret = 0; i < nlist && ret == 0; i++)
		switch (list[i].op) {
		case DB_LOCK_GET_TIMEOUT:
			LF_SET(DB_LOCK_SET_TIMEOUT);
		case DB_LOCK_GET:
			ret = __lock_get_internal(dbenv->lk_handle,
			    locker, flags, list[i].obj,
			    list[i].mode, list[i].timeout, &list[i].lock);
			break;
		case DB_LOCK_INHERIT:
			/*
			 * Get the committing locker and mark it as deleted.
			 * This allows us to traverse the locker links without
			 * worrying that someone else is deleting locks out
			 * from under us.  However, if the locker doesn't
			 * exist, that just means that the child holds no
			 * locks, so inheritance is easy!
			 */
			LOCKER_LOCK(lt, region, locker, ndx);
			if ((ret = __lock_getlocker(lt,
			    locker, ndx, 0, &sh_locker)) != 0 ||
			    sh_locker == NULL ||
			    F_ISSET(sh_locker, DB_LOCKER_DELETED)) {
				if (ret == 0 && sh_locker != NULL)
					ret = EINVAL;
				__db_err(dbenv, __db_locker_invalid);
				break;
			}

			/* Make sure we are a child transaction. */
			if (sh_locker->parent_locker == INVALID_ROFF) {
				__db_err(dbenv, "Not a child transaction");
				ret = EINVAL;
				break;
			}
			sh_parent = (DB_LOCKER *)
			    R_ADDR(&lt->reginfo, sh_locker->parent_locker);
			F_SET(sh_locker, DB_LOCKER_DELETED);

			/*
			 * Now, lock the parent locker; move locks from
			 * the committing list to the parent's list.
			 */
			LOCKER_LOCK(lt, region, locker, ndx);
			if (F_ISSET(sh_parent, DB_LOCKER_DELETED)) {
				if (ret == 0) {
					__db_err(dbenv,
					    "Parent locker is not valid");
					ret = EINVAL;
				}
				break;
			}

			for (lp = SH_LIST_FIRST(&sh_locker->heldby, __db_lock);
			    lp != NULL;
			    lp = SH_LIST_FIRST(&sh_locker->heldby, __db_lock)) {
				SH_LIST_REMOVE(lp, locker_links, __db_lock);
				SH_LIST_INSERT_HEAD(&sh_parent->heldby, lp,
				    locker_links, __db_lock);
				lp->holder = sh_parent->id;

				/* Get the object associated with this lock. */
				obj = (DB_LOCKOBJ *)((u_int8_t *)lp + lp->obj);

				(void)__lock_promote(lt, obj,
				    LF_ISSET(DB_LOCK_NOWAITERS));
			}

			/* Transfer child counts to parent. */
			sh_parent->nlocks += sh_locker->nlocks;
			sh_parent->nwrites += sh_locker->nwrites;

			/* Now free the original locker. */
			ret = __lock_checklocker(lt,
			    NULL, locker, DB_LOCK_IGNOREDEL);
			break;
		case DB_LOCK_PUT:
			ret = __lock_put_nolock(dbenv,
			    &list[i].lock, &run_dd, flags);
			break;
		case DB_LOCK_PUT_ALL:
		case DB_LOCK_PUT_READ:
		case DB_LOCK_UPGRADE_WRITE:
			/*
			 * Get the locker and mark it as deleted.  This
			 * allows us to traverse the locker links without
			 * worrying that someone else is deleting locks out
			 * from under us.  Since the locker may hold no
			 * locks (i.e., you could call abort before you've
			 * done any work), it's perfectly reasonable for there
			 * to be no locker; this is not an error.
			 */
			LOCKER_LOCK(lt, region, locker, ndx);
			if ((ret = __lock_getlocker(lt,
			    locker, ndx, 0, &sh_locker)) != 0 ||
			    sh_locker == NULL ||
			    F_ISSET(sh_locker, DB_LOCKER_DELETED))
				/*
				 * If ret is set, then we'll generate an
				 * error.  If it's not set, we have nothing
				 * to do.
				 */
				break;
			upgrade = 0;
			writes = 1;
			if (list[i].op == DB_LOCK_PUT_READ)
				writes = 0;
			else if (list[i].op == DB_LOCK_UPGRADE_WRITE) {
				if (F_ISSET(sh_locker, DB_LOCKER_DIRTY))
					upgrade = 1;
				writes = 0;
			}

			F_SET(sh_locker, DB_LOCKER_DELETED);

			/* Now traverse the locks, releasing each one. */
			for (lp = SH_LIST_FIRST(&sh_locker->heldby, __db_lock);
			    lp != NULL;) {
				sh_obj = (DB_LOCKOBJ *)
				    ((u_int8_t *)lp + lp->obj);
				if (writes == 1 || lp->mode == DB_LOCK_READ) {
					SH_LIST_REMOVE(lp,
					    locker_links, __db_lock);
					sh_obj = (DB_LOCKOBJ *)
					    ((u_int8_t *)lp + lp->obj);
					SHOBJECT_LOCK(lt, region, sh_obj, lndx);
					/*
					 * We are not letting lock_put_internal
					 * unlink the lock, so we'll have to
					 * update counts here.
					 */
					sh_locker->nlocks--;
					if (IS_WRITELOCK(lp->mode))
						sh_locker->nwrites--;
					ret = __lock_put_internal(lt, lp,
					    lndx, DB_LOCK_FREE | DB_LOCK_DOALL);
					if (ret != 0)
						break;
					lp = SH_LIST_FIRST(
					    &sh_locker->heldby, __db_lock);
				} else
					lp = SH_LIST_NEXT(lp,
					    locker_links, __db_lock);
			}
			switch (list[i].op) {
			case DB_LOCK_UPGRADE_WRITE:
				if (upgrade != 1)
					goto up_done;
				for (lp = SH_LIST_FIRST(
				    &sh_locker->heldby, __db_lock);
				    lp != NULL;
				    lp = SH_LIST_NEXT(lp,
					    locker_links, __db_lock)) {
					if (ret != 0)
						break;
					lock.off = R_OFFSET(&lt->reginfo, lp);
					lock.gen = lp->gen;
					F_SET(sh_locker, DB_LOCKER_INABORT);
					ret = __lock_get_internal(lt,
					    locker, DB_LOCK_UPGRADE,
					    NULL, DB_LOCK_WRITE, 0, &lock);
				}
			up_done:
				/* FALL THROUGH */
			case DB_LOCK_PUT_READ:
				F_CLR(sh_locker, DB_LOCKER_DELETED);
				break;

			case DB_LOCK_PUT_ALL:
				if (ret == 0)
					ret = __lock_checklocker(lt,
					    NULL, locker, DB_LOCK_IGNOREDEL);
				break;
			default:
				break;
			}
			break;
		case DB_LOCK_PUT_OBJ:
			/* Remove all the locks associated with an object. */
			OBJECT_LOCK(lt, region, list[i].obj, ndx);
			if ((ret = __lock_getobj(lt, list[i].obj,
			    ndx, 0, &sh_obj)) != 0 || sh_obj == NULL) {
				if (ret == 0)
					ret = EINVAL;
				break;
			}

			/*
			 * Go through both waiters and holders.  Don't bother
			 * to run promotion, because everyone is getting
			 * released.  The processes waiting will still get
			 * awakened as their waiters are released.
			 */
			for (lp = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock);
			    ret == 0 && lp != NULL;
			    lp = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock))
				ret = __lock_put_internal(lt, lp, ndx,
				    DB_LOCK_UNLINK |
				    DB_LOCK_NOPROMOTE | DB_LOCK_DOALL);

			/*
			 * On the last time around, the object will get
			 * reclaimed by __lock_put_internal, structure the
			 * loop carefully so we do not get bitten.
			 */
			for (lp = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock);
			    ret == 0 && lp != NULL;
			    lp = next_lock) {
				next_lock = SH_TAILQ_NEXT(lp, links, __db_lock);
				ret = __lock_put_internal(lt, lp, ndx,
				    DB_LOCK_UNLINK |
				    DB_LOCK_NOPROMOTE | DB_LOCK_DOALL);
			}
			break;

		case DB_LOCK_TIMEOUT:
			ret = __lock_set_timeout(dbenv,
			    locker, 0, DB_SET_TXN_NOW);
			region->need_dd = 1;
			break;

		case DB_LOCK_TRADE:
			/*
			 * INTERNAL USE ONLY.
			 * Change the holder of the lock described in
			 * list[i].lock to the locker-id specified by
			 * the locker parameter.
			 */
			/*
			 * You had better know what you're doing here.
			 * We are trading locker-id's on a lock to
			 * facilitate file locking on open DB handles.
			 * We do not do any conflict checking on this,
			 * so heaven help you if you use this flag under
			 * any other circumstances.
			 */
			ret = __lock_trade(dbenv, &list[i].lock, locker);
			break;
#ifdef DEBUG
		case DB_LOCK_DUMP:
			/* Find the locker. */
			LOCKER_LOCK(lt, region, locker, ndx);
			if ((ret = __lock_getlocker(lt,
			    locker, ndx, 0, &sh_locker)) != 0 ||
			    sh_locker == NULL ||
			    F_ISSET(sh_locker, DB_LOCKER_DELETED))
				break;

			for (lp = SH_LIST_FIRST(&sh_locker->heldby, __db_lock);
			    lp != NULL;
			    lp = SH_LIST_NEXT(lp, locker_links, __db_lock)) {
				__lock_printlock(lt, lp, 1);
			}
			break;
#endif
		default:
			__db_err(dbenv,
			    "Invalid lock operation: %d", list[i].op);
			ret = EINVAL;
			break;
		}

	if (ret == 0 && region->need_dd && region->detect != DB_LOCK_NORUN)
		run_dd = 1;
	UNLOCKREGION(dbenv, (DB_LOCKTAB *)dbenv->lk_handle);