diff options
Diffstat (limited to 'db2/lock/lock.c')
| -rw-r--r-- | db2/lock/lock.c | 386 |
1 files changed, 315 insertions, 71 deletions
diff --git a/db2/lock/lock.c b/db2/lock/lock.c index 3d20e0d65b..4cf1d9ecca 100644 --- a/db2/lock/lock.c +++ b/db2/lock/lock.c @@ -8,7 +8,7 @@ #include "config.h" #ifndef lint -static const char sccsid[] = "@(#)lock.c 10.52 (Sleepycat) 5/10/98"; +static const char sccsid[] = "@(#)lock.c 10.61 (Sleepycat) 1/3/99"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES @@ -23,16 +23,22 @@ static const char sccsid[] = "@(#)lock.c 10.52 (Sleepycat) 5/10/98"; #include "db_page.h" #include "db_shash.h" #include "lock.h" -#include "common_ext.h" #include "db_am.h" +#include "txn_auto.h" +#include "txn_ext.h" +#include "common_ext.h" static void __lock_checklocker __P((DB_LOCKTAB *, struct __db_lock *, int)); static void __lock_freeobj __P((DB_LOCKTAB *, DB_LOCKOBJ *)); -static int __lock_get_internal __P((DB_LOCKTAB *, u_int32_t, u_int32_t, - const DBT *, db_lockmode_t, struct __db_lock **)); +static int __lock_get_internal __P((DB_LOCKTAB *, u_int32_t, DB_TXN *, + u_int32_t, const DBT *, db_lockmode_t, struct __db_lock **)); +static int __lock_is_parent __P((u_int32_t, DB_TXN *)); +static int __lock_promote __P((DB_LOCKTAB *, DB_LOCKOBJ *)); static int __lock_put_internal __P((DB_LOCKTAB *, struct __db_lock *, int)); static void __lock_remove_waiter __P((DB_LOCKTAB *, DB_LOCKOBJ *, struct __db_lock *, db_status_t)); +static int __lock_vec_internal __P((DB_LOCKTAB *, u_int32_t, DB_TXN *, + u_int32_t, DB_LOCKREQ *, int, DB_LOCKREQ **elistp)); int lock_id(lt, idp) @@ -41,6 +47,8 @@ lock_id(lt, idp) { u_int32_t id; + LOCK_PANIC_CHECK(lt); + LOCK_LOCKREGION(lt); if (lt->region->id >= DB_LOCK_MAXID) lt->region->id = 0; @@ -58,10 +66,37 @@ lock_vec(lt, locker, flags, list, nlist, elistp) int nlist; DB_LOCKREQ *list, **elistp; { + return (__lock_vec_internal(lt, + locker, NULL, flags, list, nlist, elistp)); +} + +int +lock_tvec(lt, txn, flags, list, nlist, elistp) + DB_LOCKTAB *lt; + DB_TXN *txn; + u_int32_t flags; + int nlist; + DB_LOCKREQ *list, **elistp; +{ + return (__lock_vec_internal(lt, + txn->txnid, txn, flags, list, nlist, elistp)); +} + +static int +__lock_vec_internal(lt, locker, txn, flags, list, nlist, elistp) + DB_LOCKTAB *lt; + u_int32_t locker; + DB_TXN *txn; + u_int32_t flags; + int nlist; + DB_LOCKREQ *list, **elistp; +{ struct __db_lock *lp; - DB_LOCKOBJ *sh_obj, *sh_locker; + DB_LOCKOBJ *sh_obj, *sh_locker, *sh_parent; int i, ret, run_dd; + LOCK_PANIC_CHECK(lt); + /* Validate arguments. */ if ((ret = __db_fchk(lt->dbenv, "lock_vec", flags, DB_LOCK_NOWAIT)) != 0) @@ -78,13 +113,43 @@ lock_vec(lt, locker, flags, list, nlist, elistp) for (i = 0; i < nlist && ret == 0; i++) { switch (list[i].op) { case DB_LOCK_GET: - ret = __lock_get_internal(lt, locker, flags, + ret = __lock_get_internal(lt, locker, txn, flags, list[i].obj, list[i].mode, &lp); if (ret == 0) { list[i].lock = LOCK_TO_OFFSET(lt, lp); lt->region->nrequests++; } break; + case DB_LOCK_INHERIT: + /* Find the locker. */ + if ((ret = __lock_getobj(lt, locker, + NULL, DB_LOCK_LOCKER, &sh_locker)) != 0) + break; + if (txn == NULL || txn->parent == NULL) { + ret = EINVAL; + break; + } + + if ((ret = __lock_getobj(lt, txn->parent->txnid, + NULL, DB_LOCK_LOCKER, &sh_parent)) != 0) + break; + + /* + * Traverse all the locks held by this locker. Remove + * the locks from the locker's list and put them on the + * parent's list. + */ + 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 = txn->parent->txnid; + } + __lock_freeobj(lt, sh_locker); + lt->region->nlockers--; + break; case DB_LOCK_PUT: lp = OFFSET_TO_LOCK(lt, list[i].lock); if (lp->holder != locker) { @@ -93,8 +158,8 @@ lock_vec(lt, locker, flags, list, nlist, elistp) } list[i].mode = lp->mode; - /* XXX Need to copy the object. ??? */ ret = __lock_put_internal(lt, lp, 0); + __lock_checklocker(lt, lp, 0); break; case DB_LOCK_PUT_ALL: /* Find the locker. */ @@ -204,18 +269,25 @@ lock_get(lt, locker, flags, obj, lock_mode, lock) struct __db_lock *lockp; int ret; + LOCK_PANIC_CHECK(lt); + /* Validate arguments. */ - if ((ret = - __db_fchk(lt->dbenv, "lock_get", flags, DB_LOCK_NOWAIT)) != 0) + if ((ret = __db_fchk(lt->dbenv, + "lock_get", flags, DB_LOCK_NOWAIT | DB_LOCK_UPGRADE)) != 0) return (ret); LOCK_LOCKREGION(lt); - ret = __lock_validate_region(lt); - if (ret == 0 && (ret = __lock_get_internal(lt, - locker, flags, obj, lock_mode, &lockp)) == 0) { - *lock = LOCK_TO_OFFSET(lt, lockp); - lt->region->nrequests++; + if ((ret = __lock_validate_region(lt)) == 0) { + if (LF_ISSET(DB_LOCK_UPGRADE)) + lockp = OFFSET_TO_LOCK(lt, *lock); + + if ((ret = __lock_get_internal(lt, + locker, NULL, flags, obj, lock_mode, &lockp)) == 0) { + if (!LF_ISSET(DB_LOCK_UPGRADE)) + *lock = LOCK_TO_OFFSET(lt, lockp); + lt->region->nrequests++; + } } UNLOCK_LOCKREGION(lt); @@ -223,6 +295,42 @@ lock_get(lt, locker, flags, obj, lock_mode, lock) } int +lock_tget(lt, txn, flags, obj, lock_mode, lock) + DB_LOCKTAB *lt; + DB_TXN *txn; + u_int32_t flags; + const DBT *obj; + db_lockmode_t lock_mode; + DB_LOCK *lock; +{ + struct __db_lock *lockp; + int ret; + + LOCK_PANIC_CHECK(lt); + + /* Validate arguments. */ + if ((ret = __db_fchk(lt->dbenv, + "lock_get", flags, DB_LOCK_NOWAIT | DB_LOCK_UPGRADE)) != 0) + return (ret); + + LOCK_LOCKREGION(lt); + + if ((ret = __lock_validate_region(lt)) == 0) { + if (LF_ISSET(DB_LOCK_UPGRADE)) + lockp = OFFSET_TO_LOCK(lt, *lock); + + if ((ret = __lock_get_internal(lt, + txn->txnid, txn, flags, obj, lock_mode, &lockp)) == 0) { + if (!LF_ISSET(DB_LOCK_UPGRADE)) + *lock = LOCK_TO_OFFSET(lt, lockp); + lt->region->nrequests++; + } + } + + UNLOCK_LOCKREGION(lt); + return (ret); +} +int lock_put(lt, lock) DB_LOCKTAB *lt; DB_LOCK lock; @@ -230,6 +338,8 @@ lock_put(lt, lock) struct __db_lock *lockp; int ret, run_dd; + LOCK_PANIC_CHECK(lt); + LOCK_LOCKREGION(lt); if ((ret = __lock_validate_region(lt)) != 0) @@ -261,7 +371,6 @@ __lock_put_internal(lt, lockp, do_all) struct __db_lock *lockp; int do_all; { - struct __db_lock *lp_w, *lp_h, *next_waiter; DB_LOCKOBJ *sh_obj; int state_changed; @@ -293,39 +402,7 @@ __lock_put_internal(lt, lockp, do_all) else SH_TAILQ_REMOVE(&sh_obj->holders, lockp, links, __db_lock); - /* - * 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. - */ - for (lp_w = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock), - state_changed = lp_w == NULL; - lp_w != NULL; - lp_w = next_waiter) { - next_waiter = SH_TAILQ_NEXT(lp_w, links, __db_lock); - for (lp_h = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock); - lp_h != NULL; - lp_h = SH_TAILQ_NEXT(lp_h, links, __db_lock)) { - if (CONFLICTS(lt, lp_h->mode, lp_w->mode) && - lp_h->holder != lp_w->holder) - break; - } - if (lp_h != NULL) /* Found a conflict. */ - break; - - /* No conflict, promote the waiting lock. */ - SH_TAILQ_REMOVE(&sh_obj->waiters, lp_w, links, __db_lock); - lp_w->status = DB_LSTAT_PENDING; - SH_TAILQ_INSERT_TAIL(&sh_obj->holders, lp_w, links); - - /* Wake up waiter. */ - (void)__db_mutex_unlock(&lp_w->mutex, lt->reginfo.fd); - state_changed = 1; - } + state_changed = __lock_promote(lt, sh_obj); /* Check if object should be reclaimed. */ if (SH_TAILQ_FIRST(&sh_obj->holders, __db_lock) == NULL) { @@ -354,9 +431,10 @@ __lock_put_internal(lt, lockp, do_all) } static int -__lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) +__lock_get_internal(lt, locker, txn, flags, obj, lock_mode, lockp) DB_LOCKTAB *lt; u_int32_t locker, flags; + DB_TXN *txn; const DBT *obj; db_lockmode_t lock_mode; struct __db_lock **lockp; @@ -365,13 +443,13 @@ __lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) DB_LOCKOBJ *sh_obj, *sh_locker; DB_LOCKREGION *lrp; size_t newl_off; - int ihold, ret; + int ihold, no_dd, ret; + + no_dd = ret = 0; - ret = 0; /* * Check that lock mode is valid. */ - lrp = lt->region; if ((u_int32_t)lock_mode >= lrp->nmodes) { __db_err(lt->dbenv, @@ -423,20 +501,28 @@ __lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) * lock, then we guarantee deadlock. * * In case of conflict, we put the new lock on the end of the waiters - * list. + * list, unless we are upgrading in which case the locker goes on the + * front of the list. */ ihold = 0; 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 (locker == lp->holder || + __lock_is_parent(lp->holder, txn)) { if (lp->mode == lock_mode && lp->status == DB_LSTAT_HELD) { - /* Lock is held, just inc the ref count. */ + if (LF_ISSET(DB_LOCK_UPGRADE)) + goto upgrade; + + /* + * Lock is held, so we can increment the + * reference count and return this lock. + */ lp->refcount++; + *lockp = lp; SH_TAILQ_INSERT_HEAD(&lrp->free_locks, newl, links, __db_lock); - *lockp = lp; return (0); } else ihold = 1; @@ -444,6 +530,21 @@ __lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) break; } + /* + * 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. */ + SH_TAILQ_INSERT_HEAD(&sh_obj->waiters, newl, links, __db_lock); + goto wait; + } + if (lp == NULL && !ihold) for (lp = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock); lp != NULL; @@ -464,31 +565,35 @@ __lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) } /* - * This is really a blocker for the process, so initialize it - * set. That way the current process will block when it tries - * to get it and the waking process will release it. - */ - (void)__db_mutex_init(&newl->mutex, - MUTEX_LOCK_OFFSET(lt->region, &newl->mutex)); - (void)__db_mutex_lock(&newl->mutex, lt->reginfo.fd); - - /* - * Now, insert the lock onto its locker's list. + * 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. */ if ((ret = __lock_getobj(lt, locker, NULL, DB_LOCK_LOCKER, &sh_locker)) != 0) return (ret); + no_dd = SH_LIST_FIRST(&sh_locker->heldby, __db_lock) == NULL; lrp = lt->region; SH_LIST_INSERT_HEAD(&sh_locker->heldby, newl, locker_links, __db_lock); if (lp != NULL) { + /* + * This is really a blocker for the process, so initialize it + * set. That way the current process will block when it tries + * to get it and the waking process will release it. + */ +wait: (void)__db_mutex_init(&newl->mutex, + MUTEX_LOCK_OFFSET(lt->region, &newl->mutex)); + (void)__db_mutex_lock(&newl->mutex, lt->reginfo.fd); + newl->status = DB_LSTAT_WAITING; lrp->nconflicts++; + /* - * We are about to wait; must release the region mutex. - * Then, when we wakeup, we need to reacquire the region - * mutex before continuing. + * We are about to wait; must release the region mutex. Then, + * when we wakeup, we need to reacquire the region mutex before + * continuing. */ if (lrp->detect == DB_LOCK_NORUN) lt->region->need_dd = 1; @@ -498,13 +603,19 @@ __lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) * We are about to wait; before waiting, see if the deadlock * detector should be run. */ - if (lrp->detect != DB_LOCK_NORUN) - ret = lock_detect(lt, 0, lrp->detect); + if (lrp->detect != DB_LOCK_NORUN && !no_dd) + (void)lock_detect(lt, 0, lrp->detect); (void)__db_mutex_lock(&newl->mutex, lt->reginfo.fd); LOCK_LOCKREGION(lt); if (newl->status != DB_LSTAT_PENDING) { + /* + * If this lock errored due to a deadlock, then + * we have waiters that require promotion. + */ + if (newl->status == DB_LSTAT_ABORTED) + (void)__lock_promote(lt, sh_obj); /* Return to free list. */ __lock_checklocker(lt, newl, 0); SH_TAILQ_INSERT_HEAD(&lrp->free_locks, newl, links, @@ -522,12 +633,31 @@ __lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) } newl->status = DB_LSTAT_FREE; newl = NULL; + } 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); + goto upgrade; } else newl->status = DB_LSTAT_HELD; } *lockp = newl; return (ret); + +upgrade: + /* + * This was an upgrade, so return the new lock to the free list and + * upgrade the mode. + */ + (*lockp)->mode = lock_mode; + newl->status = DB_LSTAT_FREE; + SH_TAILQ_INSERT_HEAD(&lrp->free_locks, newl, links, __db_lock); + return (0); } /* @@ -788,3 +918,117 @@ __lock_freeobj(lt, obj) __db_shalloc_free(lt->mem, SH_DBT_PTR(&obj->lockobj)); SH_TAILQ_INSERT_HEAD(<->region->free_objs, obj, links, __db_lockobj); } + +/* + * __lock_downgrade -- + * Used by the concurrent access product to downgrade write locks + * back to iwrite locks. + * + * PUBLIC: int __lock_downgrade __P((DB_LOCKTAB *, + * PUBLIC: DB_LOCK, db_lockmode_t, u_int32_t)); + */ +int +__lock_downgrade(lt, lock, new_mode, flags) + DB_LOCKTAB *lt; + DB_LOCK lock; + db_lockmode_t new_mode; + u_int32_t flags; +{ + struct __db_lock *lockp; + DB_LOCKOBJ *obj; + int ret; + + COMPQUIET(flags, 0); + LOCK_PANIC_CHECK(lt); + LOCK_LOCKREGION(lt); + + if ((ret = __lock_validate_region(lt)) == 0) { + lockp = OFFSET_TO_LOCK(lt, lock); + 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); + ++lt->region->nreleases; + } + + UNLOCK_LOCKREGION(lt); + + return (ret); +} + +/* + * __lock_promote -- + * + * Look through the waiters and holders lists and decide which (if any) + * locks can be promoted. Promote any that are eligible. + */ +static int +__lock_promote(lt, obj) + DB_LOCKTAB *lt; + DB_LOCKOBJ *obj; +{ + struct __db_lock *lp_w, *lp_h, *next_waiter; + int state_changed, waiter_is_txn; + + /* + * 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) { + waiter_is_txn = TXN_IS_HOLDING(lp_w); + next_waiter = SH_TAILQ_NEXT(lp_w, links, __db_lock); + for (lp_h = SH_TAILQ_FIRST(&obj->holders, __db_lock); + lp_h != NULL; + lp_h = SH_TAILQ_NEXT(lp_h, links, __db_lock)) { + if (CONFLICTS(lt, lp_h->mode, lp_w->mode) && + lp_h->holder != lp_w->holder && + !(waiter_is_txn && + TXN_IS_HOLDING(lp_h) && + __txn_is_ancestor(lt->dbenv->tx_info, + lp_h->txnoff, lp_w->txnoff))) + 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. */ + (void)__db_mutex_unlock(&lp_w->mutex, lt->reginfo.fd); + state_changed = 1; + } + + return (state_changed); +} + +static int +__lock_is_parent(locker, txn) + u_int32_t locker; + DB_TXN *txn; +{ + DB_TXN *t; + + if (txn == NULL) + return (0); + + for (t = txn->parent; t != NULL; t = t->parent) + if (t->txnid == locker) + return (1); + + return (0); +} |