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mariadb/bdb/lock/lock.c
ram@mysql.r18.ru 5e09392faa BDB 4.1.24
2002-10-30 15:57:05 +04:00

1874 lines
50 KiB
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/*-
* 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static const char __db_lock_invalid[] = "%s: Lock is no longer valid";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);
if (run_dd)
(void)dbenv->lock_detect(dbenv, 0, region->detect, &did_abort);
if (ret != 0 && elistp != NULL)
*elistp = &list[i - 1];
return (ret);
}
/*
* Lock acquisition routines. There are two library interfaces:
*
* __lock_get --
* original lock get interface that takes a locker id.
*
* All the work for lock_get (and for the GET option of lock_vec) is done
* inside of lock_get_internal.
*
* PUBLIC: int __lock_get __P((DB_ENV *,
* PUBLIC: u_int32_t, u_int32_t, const DBT *, db_lockmode_t, DB_LOCK *));
*/
int
__lock_get(dbenv, locker, flags, obj, lock_mode, lock)
DB_ENV *dbenv;
u_int32_t locker, flags;
const DBT *obj;
db_lockmode_t lock_mode;
DB_LOCK *lock;
{
int ret;
PANIC_CHECK(dbenv);
ENV_REQUIRES_CONFIG(dbenv,
dbenv->lk_handle, "DB_ENV->lock_get", DB_INIT_LOCK);
if (IS_RECOVERING(dbenv)) {
LOCK_INIT(*lock);
return (0);
}
/* Validate arguments. */
if ((ret = __db_fchk(dbenv, "DB_ENV->lock_get", flags,
DB_LOCK_NOWAIT | DB_LOCK_UPGRADE | DB_LOCK_SWITCH)) != 0)
return (ret);
LOCKREGION(dbenv, (DB_LOCKTAB *)dbenv->lk_handle);
ret = __lock_get_internal(dbenv->lk_handle,
locker, flags, obj, lock_mode, 0, lock);
UNLOCKREGION(dbenv, (DB_LOCKTAB *)dbenv->lk_handle);
return (ret);
}
static int
__lock_get_internal(lt, locker, flags, obj, lock_mode, timeout, lock)
DB_LOCKTAB *lt;
u_int32_t locker, flags;
const DBT *obj;
db_lockmode_t lock_mode;
db_timeout_t timeout;
DB_LOCK *lock;
{
struct __db_lock *newl, *lp, *wwrite;
DB_ENV *dbenv;
DB_LOCKER *sh_locker;
DB_LOCKOBJ *sh_obj;
DB_LOCKREGION *region;
u_int32_t locker_ndx, obj_ndx;
int did_abort, ihold, on_locker_list, no_dd, ret;
dbenv = lt->dbenv;
region = lt->reginfo.primary;
on_locker_list = no_dd = ret = 0;
/* Check if locks have been globally turned off. */
if (F_ISSET(dbenv, DB_ENV_NOLOCKING))
return (0);
/*
* If we are not going to reuse this lock, initialize the offset to
* invalid so that if we fail it will not look like a valid lock.
*/
if (!LF_ISSET(DB_LOCK_UPGRADE | DB_LOCK_SWITCH))
LOCK_INIT(*lock);
/* Check that the lock mode is valid. */
if ((u_int32_t)lock_mode >= region->stat.st_nmodes) {
__db_err(dbenv, "DB_ENV->lock_get: invalid lock mode %lu",
(u_long)lock_mode);
return (EINVAL);
}
/* Allocate a new lock. Optimize for the common case of a grant. */
region->stat.st_nrequests++;
if ((newl = SH_TAILQ_FIRST(&region->free_locks, __db_lock)) != NULL)
SH_TAILQ_REMOVE(&region->free_locks, newl, links, __db_lock);
if (newl == NULL) {
__db_err(dbenv, __db_lock_err, "locks");
return (ENOMEM);
}
if (++region->stat.st_nlocks > region->stat.st_maxnlocks)
region->stat.st_maxnlocks = region->stat.st_nlocks;
if (obj == NULL) {
DB_ASSERT(LOCK_ISSET(*lock));
lp = (struct __db_lock *)R_ADDR(&lt->reginfo, lock->off);
sh_obj = (DB_LOCKOBJ *) ((u_int8_t *)lp + lp->obj);
} else {
/* Allocate a shared memory new object. */
OBJECT_LOCK(lt, region, obj, lock->ndx);
if ((ret = __lock_getobj(lt, obj, lock->ndx, 1, &sh_obj)) != 0)
goto err;
}
/* Get the locker, we may need it to find our parent. */
LOCKER_LOCK(lt, region, locker, locker_ndx);
if ((ret = __lock_getlocker(lt, locker,
locker_ndx, locker > DB_LOCK_MAXID ? 1 : 0, &sh_locker)) != 0) {
/*
* XXX We cannot tell if we created the object or not,
* so we don't kow if we should free it or not.
*/
goto err;
}
if (sh_locker == NULL) {
__db_err(dbenv, "Locker does not exist");
ret = EINVAL;
goto err;
}
/*
* Now we have a lock and an object and we need to see if we should
* grant the lock. We use a FIFO ordering so we can only grant a
* new lock if it does not conflict with anyone on the holders list
* OR anyone on the waiters list. The reason that we don't grant if
* there's a conflict is that this can lead to starvation (a writer
* waiting on a popularly read item will never be granted). The
* downside of this is that a waiting reader can prevent an upgrade
* from reader to writer, which is not uncommon.
*
* There is one exception to the no-conflict rule. If a lock is held
* by the requesting locker AND the new lock does not conflict with
* any other holders, then we grant the lock. The most common place
* this happens is when the holder has a WRITE lock and a READ lock
* request comes in for the same locker. If we do not grant the read
* lock, then we guarantee deadlock.
*
* In case of conflict, we put the new lock on the end of the waiters
* list, unless we are upgrading in which case the locker goes on the
* front of the list.
*/
ihold = 0;
lp = NULL;
if (LF_ISSET(DB_LOCK_SWITCH))
goto put_lock;
wwrite = NULL;
for (lp = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock);
lp != NULL;
lp = SH_TAILQ_NEXT(lp, links, __db_lock)) {
if (locker == lp->holder) {
if (lp->mode == lock_mode &&
lp->status == DB_LSTAT_HELD) {
if (LF_ISSET(DB_LOCK_UPGRADE))
goto upgrade;
/*
* Lock is held, so we can increment the
* reference count and return this lock.
* We do not count reference increments
* towards the locks held by the locker.
*/
lp->refcount++;
lock->off = R_OFFSET(&lt->reginfo, lp);
lock->gen = lp->gen;
lock->mode = lp->mode;
ret = 0;
goto done;
} else {
ihold = 1;
if (lock_mode == DB_LOCK_WRITE &&
lp->mode == DB_LOCK_WWRITE)
wwrite = lp;
}
} else if (__lock_is_parent(lt, lp->holder, sh_locker))
ihold = 1;
else if (CONFLICTS(lt, region, lp->mode, lock_mode))
break;
}
/*
* If we are looking to upgrade a WWRITE to a WRITE lock
* and there were no conflicting locks then we can just
* upgrade this lock to the one we want.
*/
if (wwrite != NULL && lp == NULL) {
lp = wwrite;
lp->mode = lock_mode;
lp->refcount++;
lock->off = R_OFFSET(&lt->reginfo, lp);
lock->gen = lp->gen;
lock->mode = lp->mode;
ret = 0;
goto done;
}
/*
* Make the new lock point to the new object, initialize fields.
*
* This lock is not linked in anywhere, so we can muck with it
* without holding any mutexes.
*/
put_lock:
newl->holder = locker;
newl->refcount = 1;
newl->mode = lock_mode;
newl->obj = SH_PTR_TO_OFF(newl, sh_obj);
newl->status = DB_LSTAT_HELD;
/*
* If we are upgrading, then there are two scenarios. Either
* we had no conflicts, so we can do the upgrade. Or, there
* is a conflict and we should wait at the HEAD of the waiters
* list.
*/
if (LF_ISSET(DB_LOCK_UPGRADE)) {
if (lp == NULL)
goto upgrade;
/*
* There was a conflict, wait. If this is the first waiter,
* add the object to the deadlock detector's list.
*/
if (SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock) == NULL)
SH_TAILQ_INSERT_HEAD(&region->dd_objs,
sh_obj, dd_links, __db_lockobj);
SH_TAILQ_INSERT_HEAD(&sh_obj->waiters, newl, links, __db_lock);
goto llist;
}
if (lp == NULL && !ihold)
for (lp = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock);
lp != NULL;
lp = SH_TAILQ_NEXT(lp, links, __db_lock)) {
if (CONFLICTS(lt, region, lp->mode, lock_mode) &&
locker != lp->holder)
break;
}
if (!LF_ISSET(DB_LOCK_SWITCH) && lp == NULL)
SH_TAILQ_INSERT_TAIL(&sh_obj->holders, newl, links);
else if (!LF_ISSET(DB_LOCK_NOWAIT)) {
/*
* If this is the first waiter, add the object to the
* deadlock detector's list.
*/
if (SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock) == NULL)
SH_TAILQ_INSERT_HEAD(&region->dd_objs,
sh_obj, dd_links, __db_lockobj);
SH_TAILQ_INSERT_TAIL(&sh_obj->waiters, newl, links);
} else {
ret = DB_LOCK_NOTGRANTED;
if (SH_LIST_FIRST(&sh_locker->heldby, __db_lock) == NULL &&
LF_ISSET(DB_LOCK_FREE_LOCKER))
__lock_freelocker(lt, region, sh_locker, locker_ndx);
region->stat.st_nnowaits++;
goto err;
}
llist:
/*
* Now, insert the lock onto its locker's list. If the locker does
* not currently hold any locks, there's no reason to run a deadlock
* detector, save that information.
*/
on_locker_list = 1;
no_dd = sh_locker->master_locker == INVALID_ROFF &&
SH_LIST_FIRST(&sh_locker->child_locker, __db_locker) == NULL &&
SH_LIST_FIRST(&sh_locker->heldby, __db_lock) == NULL;
SH_LIST_INSERT_HEAD(&sh_locker->heldby, newl, locker_links, __db_lock);
if (LF_ISSET(DB_LOCK_SWITCH) || lp != NULL) {
if (LF_ISSET(DB_LOCK_SWITCH) &&
(ret = __lock_put_nolock(dbenv,
lock, &ihold, DB_LOCK_NOWAITERS)) != 0)
goto err;
/*
* This is really a blocker for the thread. It should be
* initialized locked, so that when we try to acquire it, we
* block.
*/
newl->status = DB_LSTAT_WAITING;
region->stat.st_nconflicts++;
region->need_dd = 1;
/*
* First check to see if this txn has expired.
* If not then see if the lock timeout is past
* the expiration of the txn, if it is, use
* the txn expiration time. lk_expire is passed
* to avoid an extra call to get the time.
*/
if (__lock_expired(dbenv,
&sh_locker->lk_expire, &sh_locker->tx_expire)) {
newl->status = DB_LSTAT_ABORTED;
region->stat.st_ndeadlocks++;
region->stat.st_ntxntimeouts++;
/*
* Remove the lock from the wait queue and if
* this was the only lock on the wait queue remove
* this object from the deadlock detector object
* list.
*/
SH_LIST_REMOVE(newl, locker_links, __db_lock);
SH_TAILQ_REMOVE(
&sh_obj->waiters, newl, links, __db_lock);
if (SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock) == NULL)
SH_TAILQ_REMOVE(&region->dd_objs,
sh_obj, dd_links, __db_lockobj);
/* Clear the timeout, we are done. */
LOCK_SET_TIME_INVALID(&sh_locker->tx_expire);
goto expired;
}
/*
* If a timeout was specified in this call then it
* takes priority. If a lock timeout has been specified
* for this transaction then use that, otherwise use
* the global timeout value.
*/
if (!LF_ISSET(DB_LOCK_SET_TIMEOUT)) {
if (F_ISSET(sh_locker, DB_LOCKER_TIMEOUT))
timeout = sh_locker->lk_timeout;
else
timeout = region->lk_timeout;
}
if (timeout != 0)
__lock_expires(dbenv, &sh_locker->lk_expire, timeout);
else
LOCK_SET_TIME_INVALID(&sh_locker->lk_expire);
if (LOCK_TIME_ISVALID(&sh_locker->tx_expire) &&
(timeout == 0 || __lock_expired(dbenv,
&sh_locker->lk_expire, &sh_locker->tx_expire)))
sh_locker->lk_expire = sh_locker->tx_expire;
UNLOCKREGION(dbenv, (DB_LOCKTAB *)dbenv->lk_handle);
/*
* We are about to wait; before waiting, see if the deadlock
* detector should be run.
*/
if (region->detect != DB_LOCK_NORUN && !no_dd)
(void)dbenv->lock_detect(
dbenv, 0, region->detect, &did_abort);
MUTEX_LOCK(dbenv, &newl->mutex);
LOCKREGION(dbenv, (DB_LOCKTAB *)dbenv->lk_handle);
expired: /* Turn off lock timeout. */
LOCK_SET_TIME_INVALID(&sh_locker->lk_expire);
if (newl->status != DB_LSTAT_PENDING) {
(void)__lock_checklocker(lt, newl, newl->holder, 0);
switch (newl->status) {
case DB_LSTAT_ABORTED:
on_locker_list = 0;
ret = DB_LOCK_DEADLOCK;
break;
case DB_LSTAT_NOTEXIST:
ret = DB_LOCK_NOTEXIST;
break;
case DB_LSTAT_EXPIRED:
SHOBJECT_LOCK(lt,
region, sh_obj, obj_ndx);
if ((ret = __lock_put_internal(
lt, newl, obj_ndx, 0) != 0))
goto err;
if (LOCK_TIME_EQUAL(
&sh_locker->lk_expire,
&sh_locker->tx_expire)) {
region->stat.st_ndeadlocks++;
region->stat.st_ntxntimeouts++;
return (DB_LOCK_DEADLOCK);
} else {
region->stat.st_nlocktimeouts++;
return (DB_LOCK_NOTGRANTED);
}
default:
ret = EINVAL;
break;
}
goto err;
} else if (LF_ISSET(DB_LOCK_UPGRADE)) {
/*
* The lock that was just granted got put on the
* holders list. Since we're upgrading some other
* lock, we've got to remove it here.
*/
SH_TAILQ_REMOVE(
&sh_obj->holders, newl, links, __db_lock);
/*
* Ensure that the object is not believed to be on
* the object's lists, if we're traversing by locker.
*/
newl->links.stqe_prev = -1;
goto upgrade;
} else
newl->status = DB_LSTAT_HELD;
}
lock->off = R_OFFSET(&lt->reginfo, newl);
lock->gen = newl->gen;
lock->mode = newl->mode;
sh_locker->nlocks++;
if (IS_WRITELOCK(newl->mode))
sh_locker->nwrites++;
return (0);
upgrade:/*
* This was an upgrade, so return the new lock to the free list and
* upgrade the mode of the original lock.
*/
lp = (struct __db_lock *)R_ADDR(&lt->reginfo, lock->off);
if (IS_WRITELOCK(lock_mode) && !IS_WRITELOCK(lp->mode))
sh_locker->nwrites++;
lp->mode = lock_mode;
ret = 0;
/* FALLTHROUGH */
done:
err: newl->status = DB_LSTAT_FREE;
region->stat.st_nlocks--;
if (on_locker_list) {
SH_LIST_REMOVE(newl, locker_links, __db_lock);
}
SH_TAILQ_INSERT_HEAD(&region->free_locks, newl, links, __db_lock);
return (ret);
}
/*
* Lock release routines.
*
* The user callable one is lock_put and the three we use internally are
* __lock_put_nolock, __lock_put_internal and __lock_downgrade.
*
* PUBLIC: int __lock_put __P((DB_ENV *, DB_LOCK *));
*/
int
__lock_put(dbenv, lock)
DB_ENV *dbenv;
DB_LOCK *lock;
{
DB_LOCKTAB *lt;
int ret, run_dd;
PANIC_CHECK(dbenv);
ENV_REQUIRES_CONFIG(dbenv,
dbenv->lk_handle, "DB_LOCK->lock_put", DB_INIT_LOCK);
if (IS_RECOVERING(dbenv))
return (0);
lt = dbenv->lk_handle;
LOCKREGION(dbenv, lt);
ret = __lock_put_nolock(dbenv, lock, &run_dd, 0);
UNLOCKREGION(dbenv, lt);
/*
* Only run the lock detector if put told us to AND we are running
* in auto-detect mode. If we are not running in auto-detect, then
* a call to lock_detect here will 0 the need_dd bit, but will not
* actually abort anything.
*/
if (ret == 0 && run_dd)
(void)dbenv->lock_detect(dbenv, 0,
((DB_LOCKREGION *)lt->reginfo.primary)->detect, NULL);
return (ret);
}
static int
__lock_put_nolock(dbenv, lock, runp, flags)
DB_ENV *dbenv;
DB_LOCK *lock;
int *runp;
u_int32_t flags;
{
struct __db_lock *lockp;
DB_LOCKREGION *region;
DB_LOCKTAB *lt;
int ret;
/* Check if locks have been globally turned off. */
if (F_ISSET(dbenv, DB_ENV_NOLOCKING))
return (0);
lt = dbenv->lk_handle;
region = lt->reginfo.primary;
lockp = (struct __db_lock *)R_ADDR(&lt->reginfo, lock->off);
LOCK_INIT(*lock);
if (lock->gen != lockp->gen) {
__db_err(dbenv, __db_lock_invalid, "DB_LOCK->lock_put");
return (EINVAL);
}
ret = __lock_put_internal(lt,
lockp, lock->ndx, flags | DB_LOCK_UNLINK | DB_LOCK_FREE);
*runp = 0;
if (ret == 0 && region->need_dd && region->detect != DB_LOCK_NORUN)
*runp = 1;
return (ret);
}
/*
* __lock_downgrade --
* Used to downgrade locks. Currently this is used in two places,
* 1) by the concurrent access product to downgrade write locks
* back to iwrite locks and 2) to downgrade write-handle locks to read-handle
* locks at the end of an open/create.
*
* PUBLIC: int __lock_downgrade __P((DB_ENV *,
* PUBLIC: DB_LOCK *, db_lockmode_t, u_int32_t));
*/
int
__lock_downgrade(dbenv, lock, new_mode, flags)
DB_ENV *dbenv;
DB_LOCK *lock;
db_lockmode_t new_mode;
u_int32_t flags;
{
struct __db_lock *lockp;
DB_LOCKER *sh_locker;
DB_LOCKOBJ *obj;
DB_LOCKREGION *region;
DB_LOCKTAB *lt;
u_int32_t indx;
int ret;
COMPQUIET(flags, 0);
PANIC_CHECK(dbenv);
ret = 0;
/* Check if locks have been globally turned off. */
if (F_ISSET(dbenv, DB_ENV_NOLOCKING))
return (0);
lt = dbenv->lk_handle;
region = lt->reginfo.primary;
LOCKREGION(dbenv, lt);
lockp = (struct __db_lock *)R_ADDR(&lt->reginfo, lock->off);
if (lock->gen != lockp->gen) {
__db_err(dbenv, __db_lock_invalid, "lock_downgrade");
ret = EINVAL;
goto out;
}
LOCKER_LOCK(lt, region, lockp->holder, indx);
if ((ret = __lock_getlocker(lt, lockp->holder,
indx, 0, &sh_locker)) != 0 || sh_locker == NULL) {
if (ret == 0)
ret = EINVAL;
__db_err(dbenv, __db_locker_invalid);
goto out;
}
if (IS_WRITELOCK(lockp->mode) && !IS_WRITELOCK(new_mode))
sh_locker->nwrites--;
if (new_mode == DB_LOCK_WWRITE)
F_SET(sh_locker, DB_LOCKER_DIRTY);
lockp->mode = new_mode;
/* Get the object associated with this lock. */
obj = (DB_LOCKOBJ *)((u_int8_t *)lockp + lockp->obj);
(void)__lock_promote(lt, obj, LF_ISSET(DB_LOCK_NOWAITERS));
out: UNLOCKREGION(dbenv, lt);
return (ret);
}
static int
__lock_put_internal(lt, lockp, obj_ndx, flags)
DB_LOCKTAB *lt;
struct __db_lock *lockp;
u_int32_t obj_ndx, flags;
{
DB_LOCKOBJ *sh_obj;
DB_LOCKREGION *region;
int ret, state_changed;
region = lt->reginfo.primary;
ret = state_changed = 0;
if (!OBJ_LINKS_VALID(lockp)) {
/*
* Someone removed this lock while we were doing a release
* by locker id. We are trying to free this lock, but it's
* already been done; all we need to do is return it to the
* free list.
*/
lockp->status = DB_LSTAT_FREE;
SH_TAILQ_INSERT_HEAD(
&region->free_locks, lockp, links, __db_lock);
region->stat.st_nlocks--;
return (0);
}
if (LF_ISSET(DB_LOCK_DOALL))
region->stat.st_nreleases += lockp->refcount;
else
region->stat.st_nreleases++;
if (!LF_ISSET(DB_LOCK_DOALL) && lockp->refcount > 1) {
lockp->refcount--;
return (0);
}
/* Increment generation number. */
lockp->gen++;
/* Get the object associated with this lock. */
sh_obj = (DB_LOCKOBJ *)((u_int8_t *)lockp + lockp->obj);
/* Remove this lock from its holders/waitlist. */
if (lockp->status != DB_LSTAT_HELD && lockp->status != DB_LSTAT_PENDING)
__lock_remove_waiter(lt, sh_obj, lockp, DB_LSTAT_FREE);
else {
SH_TAILQ_REMOVE(&sh_obj->holders, lockp, links, __db_lock);
lockp->links.stqe_prev = -1;
}
if (LF_ISSET(DB_LOCK_NOPROMOTE))
state_changed = 0;
else
state_changed = __lock_promote(lt,
sh_obj, LF_ISSET(DB_LOCK_REMOVE | DB_LOCK_NOWAITERS));
if (LF_ISSET(DB_LOCK_UNLINK))
ret = __lock_checklocker(lt, lockp, lockp->holder, flags);
/* Check if object should be reclaimed. */
if (SH_TAILQ_FIRST(&sh_obj->holders, __db_lock) == NULL &&
SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock) == NULL) {
HASHREMOVE_EL(lt->obj_tab,
obj_ndx, __db_lockobj, links, sh_obj);
if (sh_obj->lockobj.size > sizeof(sh_obj->objdata))
__db_shalloc_free(lt->reginfo.addr,
SH_DBT_PTR(&sh_obj->lockobj));
SH_TAILQ_INSERT_HEAD(
&region->free_objs, sh_obj, links, __db_lockobj);
region->stat.st_nobjects--;
state_changed = 1;
}
/* Free lock. */
if (!LF_ISSET(DB_LOCK_UNLINK) && LF_ISSET(DB_LOCK_FREE)) {
lockp->status = DB_LSTAT_FREE;
SH_TAILQ_INSERT_HEAD(
&region->free_locks, lockp, links, __db_lock);
region->stat.st_nlocks--;
}
/*
* If we did not promote anyone; we need to run the deadlock
* detector again.
*/
if (state_changed == 0)
region->need_dd = 1;
return (ret);
}
/*
* Utility functions; listed alphabetically.
*/
/*
* __lock_checklocker --
* If a locker has no more locks, then we can free the object.
* Return a boolean indicating whether we freed the object or not.
*
* Must be called without the locker's lock set.
*/
static int
__lock_checklocker(lt, lockp, locker, flags)
DB_LOCKTAB *lt;
struct __db_lock *lockp;
u_int32_t locker, flags;
{
DB_ENV *dbenv;
DB_LOCKER *sh_locker;
DB_LOCKREGION *region;
u_int32_t indx;
int ret;
dbenv = lt->dbenv;
region = lt->reginfo.primary;
ret = 0;
LOCKER_LOCK(lt, region, locker, indx);
/* If the locker's list is NULL, free up the locker. */
if ((ret = __lock_getlocker(lt,
locker, indx, 0, &sh_locker)) != 0 || sh_locker == NULL) {
if (ret == 0)
ret = EINVAL;
__db_err(dbenv, __db_locker_invalid);
goto freelock;
}
if (F_ISSET(sh_locker, DB_LOCKER_DELETED)) {
LF_CLR(DB_LOCK_FREE);
if (!LF_ISSET(DB_LOCK_IGNOREDEL))
goto freelock;
}
if (LF_ISSET(DB_LOCK_UNLINK)) {
SH_LIST_REMOVE(lockp, locker_links, __db_lock);
if (lockp->status == DB_LSTAT_HELD) {
sh_locker->nlocks--;
if (IS_WRITELOCK(lockp->mode))
sh_locker->nwrites--;
}
}
if (SH_LIST_FIRST(&sh_locker->heldby, __db_lock) == NULL &&
LF_ISSET(DB_LOCK_FREE_LOCKER))
__lock_freelocker( lt, region, sh_locker, indx);
freelock:
if (LF_ISSET(DB_LOCK_FREE)) {
lockp->status = DB_LSTAT_FREE;
SH_TAILQ_INSERT_HEAD(
&region->free_locks, lockp, links, __db_lock);
region->stat.st_nlocks--;
}
return (ret);
}
/*
* __lock_addfamilylocker
* Put a locker entry in for a child transaction.
*
* PUBLIC: int __lock_addfamilylocker __P((DB_ENV *, u_int32_t, u_int32_t));
*/
int
__lock_addfamilylocker(dbenv, pid, id)
DB_ENV *dbenv;
u_int32_t pid, id;
{
DB_LOCKER *lockerp, *mlockerp;
DB_LOCKREGION *region;
DB_LOCKTAB *lt;
u_int32_t ndx;
int ret;
lt = dbenv->lk_handle;
region = lt->reginfo.primary;
LOCKREGION(dbenv, lt);
/* get/create the parent locker info */
LOCKER_LOCK(lt, region, pid, ndx);
if ((ret = __lock_getlocker(dbenv->lk_handle,
pid, ndx, 1, &mlockerp)) != 0)
goto err;
/*
* We assume that only one thread can manipulate
* a single transaction family.
* Therefore the master locker cannot go away while
* we manipulate it, nor can another child in the
* family be created at the same time.
*/
LOCKER_LOCK(lt, region, id, ndx);
if ((ret = __lock_getlocker(dbenv->lk_handle,
id, ndx, 1, &lockerp)) != 0)
goto err;
/* Point to our parent. */
lockerp->parent_locker = R_OFFSET(&lt->reginfo, mlockerp);
/* See if this locker is the family master. */
if (mlockerp->master_locker == INVALID_ROFF)
lockerp->master_locker = R_OFFSET(&lt->reginfo, mlockerp);
else {
lockerp->master_locker = mlockerp->master_locker;
mlockerp = R_ADDR(&lt->reginfo, mlockerp->master_locker);
}
/*
* Link the child at the head of the master's list.
* The guess is when looking for deadlock that
* the most recent child is the one thats blocked.
*/
SH_LIST_INSERT_HEAD(
&mlockerp->child_locker, lockerp, child_link, __db_locker);
err:
UNLOCKREGION(dbenv, lt);
return (ret);
}
/*
* __lock_freefamilylocker
* Remove a locker from the hash table and its family.
*
* This must be called without the locker bucket locked.
*
* PUBLIC: int __lock_freefamilylocker __P((DB_LOCKTAB *, u_int32_t));
*/
int
__lock_freefamilylocker(lt, locker)
DB_LOCKTAB *lt;
u_int32_t locker;
{
DB_ENV *dbenv;
DB_LOCKER *sh_locker;
DB_LOCKREGION *region;
u_int32_t indx;
int ret;
dbenv = lt->dbenv;
region = lt->reginfo.primary;
LOCKREGION(dbenv, lt);
LOCKER_LOCK(lt, region, locker, indx);
if ((ret = __lock_getlocker(lt,
locker, indx, 0, &sh_locker)) != 0 || sh_locker == NULL)
goto freelock;
if (SH_LIST_FIRST(&sh_locker->heldby, __db_lock) != NULL) {
ret = EINVAL;
__db_err(dbenv, "Freeing locker with locks");
goto freelock;
}
/* If this is part of a family, we must fix up its links. */
if (sh_locker->master_locker != INVALID_ROFF)
SH_LIST_REMOVE(sh_locker, child_link, __db_locker);
__lock_freelocker(lt, region, sh_locker, indx);
freelock:
UNLOCKREGION(dbenv, lt);
return (ret);
}
/*
* __lock_freelocker
* common code for deleting a locker.
*
* This must be called with the locker bucket locked.
*/
static void
__lock_freelocker(lt, region, sh_locker, indx)
DB_LOCKTAB *lt;
DB_LOCKREGION *region;
DB_LOCKER *sh_locker;
u_int32_t indx;
{
HASHREMOVE_EL(
lt->locker_tab, indx, __db_locker, links, sh_locker);
SH_TAILQ_INSERT_HEAD(
&region->free_lockers, sh_locker, links, __db_locker);
SH_TAILQ_REMOVE(&region->lockers, sh_locker, ulinks, __db_locker);
region->stat.st_nlockers--;
}
/*
* __lock_set_timeout
* -- set timeout values in shared memory.
* This is called from the transaction system.
* We either set the time that this tranaction expires or the
* amount of time that a lock for this transaction is permitted
* to wait.
*
* PUBLIC: int __lock_set_timeout __P(( DB_ENV *,
* PUBLIC: u_int32_t, db_timeout_t, u_int32_t));
*/
int
__lock_set_timeout(dbenv, locker, timeout, op)
DB_ENV *dbenv;
u_int32_t locker;
db_timeout_t timeout;
u_int32_t op;
{
DB_LOCKER *sh_locker;
DB_LOCKREGION *region;
DB_LOCKTAB *lt;
u_int32_t locker_ndx;
int ret;
lt = dbenv->lk_handle;
region = lt->reginfo.primary;
LOCKREGION(dbenv, lt);
LOCKER_LOCK(lt, region, locker, locker_ndx);
ret = __lock_getlocker(lt, locker, locker_ndx, 1, &sh_locker);
UNLOCKREGION(dbenv, lt);
if (ret != 0)
return (ret);
if (op == DB_SET_TXN_TIMEOUT) {
if (timeout == 0)
LOCK_SET_TIME_INVALID(&sh_locker->tx_expire);
else
__lock_expires(dbenv, &sh_locker->tx_expire, timeout);
} else if (op == DB_SET_LOCK_TIMEOUT) {
sh_locker->lk_timeout = timeout;
F_SET(sh_locker, DB_LOCKER_TIMEOUT);
} else if (op == DB_SET_TXN_NOW) {
LOCK_SET_TIME_INVALID(&sh_locker->tx_expire);
__lock_expires(dbenv, &sh_locker->tx_expire, 0);
sh_locker->lk_expire = sh_locker->tx_expire;
} else
return (EINVAL);
return (0);
}
/*
* __lock_inherit_timeout
* -- inherit timeout values from parent locker.
* This is called from the transaction system. This will
* return EINVAL if the parent does not exist or did not
* have a current txn timeout set.
*
* PUBLIC: int __lock_inherit_timeout __P(( DB_ENV *, u_int32_t, u_int32_t));
*/
int
__lock_inherit_timeout(dbenv, parent, locker)
DB_ENV *dbenv;
u_int32_t parent, locker;
{
DB_LOCKER *parent_locker, *sh_locker;
DB_LOCKREGION *region;
DB_LOCKTAB *lt;
u_int32_t locker_ndx;
int ret;
lt = dbenv->lk_handle;
region = lt->reginfo.primary;
ret = 0;
LOCKREGION(dbenv, lt);
/* If the parent does not exist, we are done. */
LOCKER_LOCK(lt, region, parent, locker_ndx);
if ((ret = __lock_getlocker(lt,
parent, locker_ndx, 0, &parent_locker)) != 0)
goto err;
/*
* If the parent is not there yet, thats ok. If it
* does not have any timouts set, then avoid creating
* the child locker at this point.
*/
if (parent_locker == NULL ||
(LOCK_TIME_ISVALID(&parent_locker->tx_expire) &&
!F_ISSET(parent_locker, DB_LOCKER_TIMEOUT))) {
ret = EINVAL;
goto done;
}
LOCKER_LOCK(lt, region, locker, locker_ndx);
if ((ret = __lock_getlocker(lt,
locker, locker_ndx, 1, &sh_locker)) != 0)
goto err;
sh_locker->tx_expire = parent_locker->tx_expire;
if (F_ISSET(parent_locker, DB_LOCKER_TIMEOUT)) {
sh_locker->lk_timeout = parent_locker->lk_timeout;
F_SET(sh_locker, DB_LOCKER_TIMEOUT);
if (!LOCK_TIME_ISVALID(&parent_locker->tx_expire))
ret = EINVAL;
}
done:
err:
UNLOCKREGION(dbenv, lt);
return (ret);
}
/*
* __lock_getlocker --
* Get a locker in the locker hash table. The create parameter
* indicates if the locker should be created if it doesn't exist in
* the table.
*
* This must be called with the locker bucket locked.
*
* PUBLIC: int __lock_getlocker __P((DB_LOCKTAB *,
* PUBLIC: u_int32_t, u_int32_t, int, DB_LOCKER **));
*/
int
__lock_getlocker(lt, locker, indx, create, retp)
DB_LOCKTAB *lt;
u_int32_t locker, indx;
int create;
DB_LOCKER **retp;
{
DB_ENV *dbenv;
DB_LOCKER *sh_locker;
DB_LOCKREGION *region;
dbenv = lt->dbenv;
region = lt->reginfo.primary;
HASHLOOKUP(lt->locker_tab,
indx, __db_locker, links, locker, sh_locker, __lock_locker_cmp);
/*
* If we found the locker, then we can just return it. If
* we didn't find the locker, then we need to create it.
*/
if (sh_locker == NULL && create) {
/* Create new locker and then insert it into hash table. */
if ((sh_locker = SH_TAILQ_FIRST(
&region->free_lockers, __db_locker)) == NULL) {
__db_err(dbenv, __db_lock_err, "locker entries");
return (ENOMEM);
}
SH_TAILQ_REMOVE(
&region->free_lockers, sh_locker, links, __db_locker);
if (++region->stat.st_nlockers > region->stat.st_maxnlockers)
region->stat.st_maxnlockers = region->stat.st_nlockers;
sh_locker->id = locker;
sh_locker->dd_id = 0;
sh_locker->master_locker = INVALID_ROFF;
sh_locker->parent_locker = INVALID_ROFF;
SH_LIST_INIT(&sh_locker->child_locker);
sh_locker->flags = 0;
SH_LIST_INIT(&sh_locker->heldby);
sh_locker->nlocks = 0;
sh_locker->nwrites = 0;
sh_locker->lk_timeout = 0;
LOCK_SET_TIME_INVALID(&sh_locker->tx_expire);
if (locker < TXN_MINIMUM && region->tx_timeout != 0)
__lock_expires(dbenv,
&sh_locker->tx_expire, region->tx_timeout);
LOCK_SET_TIME_INVALID(&sh_locker->lk_expire);
HASHINSERT(lt->locker_tab, indx, __db_locker, links, sh_locker);
SH_TAILQ_INSERT_HEAD(&region->lockers,
sh_locker, ulinks, __db_locker);
}
*retp = sh_locker;
return (0);
}
/*
* __lock_getobj --
* Get an object in the object hash table. The create parameter
* indicates if the object should be created if it doesn't exist in
* the table.
*
* This must be called with the object bucket locked.
*/
static int
__lock_getobj(lt, obj, ndx, create, retp)
DB_LOCKTAB *lt;
const DBT *obj;
u_int32_t ndx;
int create;
DB_LOCKOBJ **retp;
{
DB_ENV *dbenv;
DB_LOCKOBJ *sh_obj;
DB_LOCKREGION *region;
int ret;
void *p;
dbenv = lt->dbenv;
region = lt->reginfo.primary;
/* Look up the object in the hash table. */
HASHLOOKUP(lt->obj_tab,
ndx, __db_lockobj, links, obj, sh_obj, __lock_cmp);
/*
* If we found the object, then we can just return it. If
* we didn't find the object, then we need to create it.
*/
if (sh_obj == NULL && create) {
/* Create new object and then insert it into hash table. */
if ((sh_obj =
SH_TAILQ_FIRST(&region->free_objs, __db_lockobj)) == NULL) {
__db_err(lt->dbenv, __db_lock_err, "object entries");
ret = ENOMEM;
goto err;
}
/*
* If we can fit this object in the structure, do so instead
* of shalloc-ing space for it.
*/
if (obj->size <= sizeof(sh_obj->objdata))
p = sh_obj->objdata;
else if ((ret = __db_shalloc(
lt->reginfo.addr, obj->size, 0, &p)) != 0) {
__db_err(dbenv, "No space for lock object storage");
goto err;
}
memcpy(p, obj->data, obj->size);
SH_TAILQ_REMOVE(
&region->free_objs, sh_obj, links, __db_lockobj);
if (++region->stat.st_nobjects > region->stat.st_maxnobjects)
region->stat.st_maxnobjects = region->stat.st_nobjects;
SH_TAILQ_INIT(&sh_obj->waiters);
SH_TAILQ_INIT(&sh_obj->holders);
sh_obj->lockobj.size = obj->size;
sh_obj->lockobj.off = SH_PTR_TO_OFF(&sh_obj->lockobj, p);
HASHINSERT(lt->obj_tab, ndx, __db_lockobj, links, sh_obj);
}
*retp = sh_obj;
return (0);
err: return (ret);
}
/*
* __lock_is_parent --
* Given a locker and a transaction, return 1 if the locker is
* an ancestor of the designcated transaction. This is used to determine
* if we should grant locks that appear to conflict, but don't because
* the lock is already held by an ancestor.
*/
static int
__lock_is_parent(lt, locker, sh_locker)
DB_LOCKTAB *lt;
u_int32_t locker;
DB_LOCKER *sh_locker;
{
DB_LOCKER *parent;
parent = sh_locker;
while (parent->parent_locker != INVALID_ROFF) {
parent = (DB_LOCKER *)
R_ADDR(&lt->reginfo, parent->parent_locker);
if (parent->id == locker)
return (1);
}
return (0);
}
/*
* __lock_promote --
*
* Look through the waiters and holders lists and decide which (if any)
* locks can be promoted. Promote any that are eligible.
*
* PUBLIC: int __lock_promote __P((DB_LOCKTAB *, DB_LOCKOBJ *, u_int32_t));
*/
int
__lock_promote(lt, obj, flags)
DB_LOCKTAB *lt;
DB_LOCKOBJ *obj;
u_int32_t flags;
{
struct __db_lock *lp_w, *lp_h, *next_waiter;
DB_LOCKER *sh_locker;
DB_LOCKREGION *region;
u_int32_t locker_ndx;
int had_waiters, state_changed;
region = lt->reginfo.primary;
had_waiters = 0;
/*
* We need to do lock promotion. We also need to determine if we're
* going to need to run the deadlock detector again. If we release
* locks, and there are waiters, but no one gets promoted, then we
* haven't fundamentally changed the lockmgr state, so we may still
* have a deadlock and we have to run again. However, if there were
* no waiters, or we actually promoted someone, then we are OK and we
* don't have to run it immediately.
*
* During promotion, we look for state changes so we can return this
* information to the caller.
*/
for (lp_w = SH_TAILQ_FIRST(&obj->waiters, __db_lock),
state_changed = lp_w == NULL;
lp_w != NULL;
lp_w = next_waiter) {
had_waiters = 1;
next_waiter = SH_TAILQ_NEXT(lp_w, links, __db_lock);
/* Waiter may have aborted or expired. */
if (lp_w->status != DB_LSTAT_WAITING)
continue;
/* Are we switching locks? */
if (LF_ISSET(DB_LOCK_NOWAITERS) && lp_w->mode == DB_LOCK_WAIT)
continue;
if (LF_ISSET(DB_LOCK_REMOVE)) {
__lock_remove_waiter(lt, obj, lp_w, DB_LSTAT_NOTEXIST);
continue;
}
for (lp_h = SH_TAILQ_FIRST(&obj->holders, __db_lock);
lp_h != NULL;
lp_h = SH_TAILQ_NEXT(lp_h, links, __db_lock)) {
if (lp_h->holder != lp_w->holder &&
CONFLICTS(lt, region, lp_h->mode, lp_w->mode)) {
LOCKER_LOCK(lt,
region, lp_w->holder, locker_ndx);
if ((__lock_getlocker(lt, lp_w->holder,
locker_ndx, 0, &sh_locker)) != 0) {
DB_ASSERT(0);
break;
}
if (!__lock_is_parent(lt,
lp_h->holder, sh_locker))
break;
}
}
if (lp_h != NULL) /* Found a conflict. */
break;
/* No conflict, promote the waiting lock. */
SH_TAILQ_REMOVE(&obj->waiters, lp_w, links, __db_lock);
lp_w->status = DB_LSTAT_PENDING;
SH_TAILQ_INSERT_TAIL(&obj->holders, lp_w, links);
/* Wake up waiter. */
MUTEX_UNLOCK(lt->dbenv, &lp_w->mutex);
state_changed = 1;
}
/*
* If this object had waiters and doesn't any more, then we need
* to remove it from the dd_obj list.
*/
if (had_waiters && SH_TAILQ_FIRST(&obj->waiters, __db_lock) == NULL)
SH_TAILQ_REMOVE(&region->dd_objs, obj, dd_links, __db_lockobj);
return (state_changed);
}
/*
* __lock_remove_waiter --
* Any lock on the waitlist has a process waiting for it. Therefore,
* we can't return the lock to the freelist immediately. Instead, we can
* remove the lock from the list of waiters, set the status field of the
* lock, and then let the process waking up return the lock to the
* free list.
*
* This must be called with the Object bucket locked.
*/
static void
__lock_remove_waiter(lt, sh_obj, lockp, status)
DB_LOCKTAB *lt;
DB_LOCKOBJ *sh_obj;
struct __db_lock *lockp;
db_status_t status;
{
DB_LOCKREGION *region;
int do_wakeup;
region = lt->reginfo.primary;
do_wakeup = lockp->status == DB_LSTAT_WAITING;
SH_TAILQ_REMOVE(&sh_obj->waiters, lockp, links, __db_lock);
lockp->links.stqe_prev = -1;
lockp->status = status;
if (SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock) == NULL)
SH_TAILQ_REMOVE(
&region->dd_objs,
sh_obj, dd_links, __db_lockobj);
/*
* Wake whoever is waiting on this lock.
*
* The MUTEX_UNLOCK macro normally resolves to a single argument,
* keep the compiler quiet.
*/
if (do_wakeup)
MUTEX_UNLOCK(lt->dbenv, &lockp->mutex);
}
/*
* __lock_expires -- set the expire time given the time to live.
* We assume that if timevalp is set then it contains "now".
* This avoids repeated system calls to get the time.
*/
static void
__lock_expires(dbenv, timevalp, timeout)
DB_ENV *dbenv;
db_timeval_t *timevalp;
db_timeout_t timeout;
{
if (!LOCK_TIME_ISVALID(timevalp))
__os_clock(dbenv, &timevalp->tv_sec, &timevalp->tv_usec);
if (timeout > 1000000) {
timevalp->tv_sec += timeout / 1000000;
timevalp->tv_usec += timeout % 1000000;
} else
timevalp->tv_usec += timeout;
if (timevalp->tv_usec > 1000000) {
timevalp->tv_sec++;
timevalp->tv_usec -= 1000000;
}
}
/*
* __lock_expired -- determine if a lock has expired.
*
* PUBLIC: int __lock_expired __P((DB_ENV *, db_timeval_t *, db_timeval_t *));
*/
int
__lock_expired(dbenv, now, timevalp)
DB_ENV *dbenv;
db_timeval_t *now, *timevalp;
{
if (!LOCK_TIME_ISVALID(timevalp))
return (0);
if (!LOCK_TIME_ISVALID(now))
__os_clock(dbenv, &now->tv_sec, &now->tv_usec);
return (now->tv_sec > timevalp->tv_sec ||
(now->tv_sec == timevalp->tv_sec &&
now->tv_usec >= timevalp->tv_usec));
}
/*
* __lock_trade --
*
* Trade locker ids on a lock. This is used to reassign file locks from
* a transactional locker id to a long-lived locker id. This should be
* called with the region mutex held.
*/
static int
__lock_trade(dbenv, lock, new_locker)
DB_ENV *dbenv;
DB_LOCK *lock;
u_int32_t new_locker;
{
struct __db_lock *lp;
DB_LOCKREGION *region;
DB_LOCKTAB *lt;
DB_LOCKER *sh_locker;
int ret;
u_int32_t locker_ndx;
lt = dbenv->lk_handle;
region = lt->reginfo.primary;
lp = (struct __db_lock *)R_ADDR(&lt->reginfo, lock->off);
/* If the lock is already released, simply return. */
if (lp->gen != lock->gen)
return (DB_NOTFOUND);
/* Make sure that we can get new locker and add this lock to it. */
LOCKER_LOCK(lt, region, new_locker, locker_ndx);
if ((ret =
__lock_getlocker(lt, new_locker, locker_ndx, 0, &sh_locker)) != 0)
return (ret);
if (sh_locker == NULL) {
__db_err(dbenv, "Locker does not exist");
return (EINVAL);
}
/* Remove the lock from its current locker. */
if ((ret = __lock_checklocker(lt, lp, lp->holder, DB_LOCK_UNLINK)) != 0)
return (ret);
/* Add lock to its new locker. */
SH_LIST_INSERT_HEAD(&sh_locker->heldby, lp, locker_links, __db_lock);
sh_locker->nlocks++;
if (IS_WRITELOCK(lp->mode))
sh_locker->nwrites++;
lp->holder = new_locker;
return (0);
}
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