diff options
Diffstat (limited to 'db2/lock/lock.c')
| -rw-r--r-- | db2/lock/lock.c | 1362 |
1 files changed, 1362 insertions, 0 deletions
diff --git a/db2/lock/lock.c b/db2/lock/lock.c new file mode 100644 index 0000000000..8fc91334a7 --- /dev/null +++ b/db2/lock/lock.c @@ -0,0 +1,1362 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996, 1997 + * Sleepycat Software. All rights reserved. + */ + +#include "config.h" + +#ifndef lint +static const char sccsid[] = "@(#)lock.c 10.31 (Sleepycat) 8/17/97"; +#endif /* not lint */ + +#ifndef NO_SYSTEM_INCLUDES +#include <sys/types.h> +#include <sys/mman.h> +#include <sys/stat.h> + +#include <errno.h> +#include <fcntl.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#endif + +#include "db_int.h" +#include "shqueue.h" +#include "db_page.h" +#include "db_shash.h" +#include "lock.h" +#include "common_ext.h" +#include "db_am.h" + +static void __lock_checklocker __P((DB_LOCKTAB *, struct __db_lock *, int)); +static int __lock_count_locks __P((DB_LOCKREGION *)); +static int __lock_count_objs __P((DB_LOCKREGION *)); +static int __lock_create __P((const char *, int, DB_ENV *)); +static void __lock_freeobj __P((DB_LOCKTAB *, DB_LOCKOBJ *)); +static int __lock_get_internal __P((DB_LOCKTAB *, u_int32_t, int, const DBT *, + db_lockmode_t, struct __db_lock **)); +static int __lock_grow_region __P((DB_LOCKTAB *, int, size_t)); +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 void __lock_reset_region __P((DB_LOCKTAB *)); +static int __lock_validate_region __P((DB_LOCKTAB *)); +#ifdef DEBUG +static void __lock_dump_locker __P((DB_LOCKTAB *, DB_LOCKOBJ *)); +static void __lock_dump_object __P((DB_LOCKTAB *, DB_LOCKOBJ *)); +static void __lock_printlock __P((DB_LOCKTAB *, struct __db_lock *, int)); +#endif + +/* + * Create and initialize a lock region in shared memory. + */ + +/* + * __lock_create -- + * Create the lock region. Returns an errno. In most cases, + * the errno should be that returned by __db_ropen, in which case + * an EAGAIN means that we should retry, and an EEXIST means that + * the region exists and we didn't need to create it. Any other + * sort of errno should be treated as a system error, leading to a + * failure of the original interface call. + */ +static int +__lock_create(path, mode, dbenv) + const char *path; + int mode; + DB_ENV *dbenv; +{ + struct __db_lock *lp; + struct lock_header *tq_head; + struct obj_header *obj_head; + DB_LOCKOBJ *op; + DB_LOCKREGION *lrp; + u_int maxlocks; + u_int32_t i; + int fd, lock_modes, nelements, ret; + u_int8_t *conflicts, *curaddr; + + maxlocks = dbenv == NULL || dbenv->lk_max == 0 ? + DB_LOCK_DEFAULT_N : dbenv->lk_max; + lock_modes = dbenv == NULL || dbenv->lk_modes == 0 ? + DB_LOCK_RW_N : dbenv->lk_modes; + conflicts = dbenv == NULL || dbenv->lk_conflicts == NULL ? + (u_int8_t *)db_rw_conflicts : dbenv->lk_conflicts; + + if ((ret = + __db_rcreate(dbenv, DB_APP_NONE, path, DB_DEFAULT_LOCK_FILE, mode, + LOCK_REGION_SIZE(lock_modes, maxlocks, __db_tablesize(maxlocks)), + &fd, &lrp)) != 0) + return (ret); + + /* Region exists; now initialize it. */ + lrp->table_size = __db_tablesize(maxlocks); + lrp->magic = DB_LOCKMAGIC; + lrp->version = DB_LOCKVERSION; + lrp->id = 0; + lrp->maxlocks = maxlocks; + lrp->need_dd = 0; + lrp->detect = DB_LOCK_NORUN; + lrp->numobjs = maxlocks; + lrp->nlockers = 0; + lrp->mem_bytes = ALIGN(STRING_SIZE(maxlocks), sizeof(size_t)); + lrp->increment = lrp->hdr.size / 2; + lrp->nmodes = lock_modes; + lrp->nconflicts = 0; + lrp->nrequests = 0; + lrp->nreleases = 0; + lrp->ndeadlocks = 0; + + /* + * As we write the region, we've got to maintain the alignment + * for the structures that follow each chunk. This information + * ends up being encapsulated both in here as well as in the + * lock.h file for the XXX_SIZE macros. + */ + /* Initialize conflict matrix. */ + curaddr = (u_int8_t *)lrp + sizeof(DB_LOCKREGION); + memcpy(curaddr, conflicts, lock_modes * lock_modes); + curaddr += lock_modes * lock_modes; + + /* + * Initialize hash table. + */ + curaddr = (u_int8_t *)ALIGNP(curaddr, LOCK_HASH_ALIGN); + lrp->hash_off = curaddr - (u_int8_t *)lrp; + nelements = lrp->table_size; + __db_hashinit(curaddr, nelements); + curaddr += nelements * sizeof(DB_HASHTAB); + + /* + * Initialize locks onto a free list. Since locks contains mutexes, + * we need to make sure that each lock is aligned on a MUTEX_ALIGNMENT + * boundary. + */ + curaddr = (u_int8_t *)ALIGNP(curaddr, MUTEX_ALIGNMENT); + tq_head = &lrp->free_locks; + SH_TAILQ_INIT(tq_head); + + for (i = 0; i++ < maxlocks; + curaddr += ALIGN(sizeof(struct __db_lock), MUTEX_ALIGNMENT)) { + lp = (struct __db_lock *)curaddr; + lp->status = DB_LSTAT_FREE; + SH_TAILQ_INSERT_HEAD(tq_head, lp, links, __db_lock); + } + + /* Initialize objects onto a free list. */ + obj_head = &lrp->free_objs; + SH_TAILQ_INIT(obj_head); + + for (i = 0; i++ < maxlocks; curaddr += sizeof(DB_LOCKOBJ)) { + op = (DB_LOCKOBJ *)curaddr; + SH_TAILQ_INSERT_HEAD(obj_head, op, links, __db_lockobj); + } + + /* + * Initialize the string space; as for all shared memory allocation + * regions, this requires size_t alignment, since we store the + * lengths of malloc'd areas in the area.. + */ + curaddr = (u_int8_t *)ALIGNP(curaddr, sizeof(size_t)); + lrp->mem_off = curaddr - (u_int8_t *)lrp; + __db_shalloc_init(curaddr, lrp->mem_bytes); + + /* Release the lock. */ + (void)__db_mutex_unlock(&lrp->hdr.lock, fd); + + /* Now unmap the region. */ + if ((ret = __db_rclose(dbenv, fd, lrp)) != 0) { + (void)lock_unlink(path, 1 /* force */, dbenv); + return (ret); + } + + return (0); +} + +int +lock_open(path, flags, mode, dbenv, ltp) + const char *path; + int flags, mode; + DB_ENV *dbenv; + DB_LOCKTAB **ltp; +{ + DB_LOCKTAB *lt; + int ret, retry_cnt; + + /* Validate arguments. */ +#ifdef HAVE_SPINLOCKS +#define OKFLAGS (DB_CREATE | DB_THREAD) +#else +#define OKFLAGS (DB_CREATE) +#endif + if ((ret = __db_fchk(dbenv, "lock_open", flags, OKFLAGS)) != 0) + return (ret); + + /* + * Create the lock table structure. + */ + if ((lt = (DB_LOCKTAB *)calloc(1, sizeof(DB_LOCKTAB))) == NULL) { + __db_err(dbenv, "%s", strerror(errno)); + return (ENOMEM); + } + lt->dbenv = dbenv; + + /* + * Now, create the lock region if it doesn't already exist. + */ + retry_cnt = 0; +retry: if (LF_ISSET(DB_CREATE) && + (ret = __lock_create(path, mode, dbenv)) != 0) + if (ret == EAGAIN && ++retry_cnt < 3) { + (void)__db_sleep(1, 0); + goto retry; + } else if (ret == EEXIST) /* We did not create the region */ + LF_CLR(DB_CREATE); + else + goto out; + + /* + * Finally, open the region, map it in, and increment the + * reference count. + */ + retry_cnt = 0; +retry1: if ((ret = __db_ropen(dbenv, DB_APP_NONE, path, DB_DEFAULT_LOCK_FILE, + LF_ISSET(~(DB_CREATE | DB_THREAD)), <->fd, <->region)) != 0) { + if (ret == EAGAIN && ++retry_cnt < 3) { + (void)__db_sleep(1, 0); + goto retry1; + } + goto out; + } + + if (lt->region->magic != DB_LOCKMAGIC) { + __db_err(dbenv, "lock_open: Bad magic number"); + ret = EINVAL; + goto out; + } + + /* Check for automatic deadlock detection. */ + if (dbenv->lk_detect != DB_LOCK_NORUN) { + if (lt->region->detect != DB_LOCK_NORUN && + dbenv->lk_detect != DB_LOCK_DEFAULT && + lt->region->detect != dbenv->lk_detect) { + __db_err(dbenv, + "lock_open: incompatible deadlock detector mode"); + ret = EINVAL; + goto out; + } + if (lt->region->detect == DB_LOCK_NORUN) + lt->region->detect = dbenv->lk_detect; + } + + /* Set up remaining pointers into region. */ + lt->conflicts = (u_int8_t *)lt->region + sizeof(DB_LOCKREGION); + lt->hashtab = + (DB_HASHTAB *)((u_int8_t *)lt->region + lt->region->hash_off); + lt->mem = (void *)((u_int8_t *)lt->region + lt->region->mem_off); + lt->reg_size = lt->region->hdr.size; + + *ltp = lt; + return (0); + +/* Error handling. */ +out: if (lt->region != NULL) + (void)__db_rclose(lt->dbenv, lt->fd, lt->region); + if (LF_ISSET(DB_CREATE)) + (void)lock_unlink(path, 1, lt->dbenv); + free(lt); + return (ret); +} + +int +lock_id (lt, idp) + DB_LOCKTAB *lt; + u_int32_t *idp; +{ + u_int32_t id; + + LOCK_LOCKREGION(lt); + if (lt->region->id >= DB_LOCK_MAXID) + lt->region->id = 0; + id = ++lt->region->id; + UNLOCK_LOCKREGION(lt); + + *idp = id; + return (0); +} + +int +lock_vec(lt, locker, flags, list, nlist, elistp) + DB_LOCKTAB *lt; + u_int32_t locker; + int flags, nlist; + DB_LOCKREQ *list, **elistp; +{ + struct __db_lock *lp; + DB_LOCKOBJ *sh_obj, *sh_locker; + int i, ret, run_dd; + + /* Validate arguments. */ + if ((ret = + __db_fchk(lt->dbenv, "lock_vec", flags, DB_LOCK_NOWAIT)) != 0) + return (ret); + + LOCK_LOCKREGION(lt); + + if ((ret = __lock_validate_region(lt)) != 0) { + UNLOCK_LOCKREGION(lt); + return (ret); + } + + ret = 0; + for (i = 0; i < nlist && ret == 0; i++) { + switch (list[i].op) { + case DB_LOCK_GET: + ret = __lock_get_internal(lt, locker, flags, + list[i].obj, list[i].mode, &lp); + if (ret == 0) + list[i].lock = LOCK_TO_OFFSET(lt, lp); + break; + case DB_LOCK_PUT: + lp = OFFSET_TO_LOCK(lt, list[i].lock); + if (lp->holder != locker) { + ret = DB_LOCK_NOTHELD; + break; + } + list[i].mode = lp->mode; + + /* XXX Need to copy the object. ??? */ + ret = __lock_put_internal(lt, lp, 0); + break; + case DB_LOCK_PUT_ALL: + /* Find the locker. */ + if ((ret = __lock_getobj(lt, locker, + NULL, DB_LOCK_LOCKER, &sh_locker)) != 0) + break; + + for (lp = SH_LIST_FIRST(&sh_locker->heldby, __db_lock); + lp != NULL; + lp = SH_LIST_FIRST(&sh_locker->heldby, __db_lock)) { + if ((ret = __lock_put_internal(lt, lp, 0)) != 0) + break; + } + __lock_freeobj(lt, sh_locker); + lt->region->nlockers--; + break; + case DB_LOCK_PUT_OBJ: + + /* Look up the object in the hash table. */ + __db_hashlookup(lt->hashtab, __db_lockobj, links, + list[i].obj, sh_obj, lt->region->table_size, + __lock_ohash, __lock_cmp); + if (sh_obj == NULL) { + ret = EINVAL; + break; + } + /* + * Release waiters first, because they won't cause + * anyone else to be awakened. If we release the + * lockers first, all the waiters get awakened + * needlessly. + */ + for (lp = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock); + lp != NULL; + lp = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock)) { + lt->region->nreleases += lp->refcount; + __lock_remove_waiter(lt, sh_obj, lp, + DB_LSTAT_NOGRANT); + __lock_checklocker(lt, lp, 1); + } + + for (lp = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock); + lp != NULL; + lp = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock)) { + + lt->region->nreleases += lp->refcount; + SH_LIST_REMOVE(lp, locker_links, __db_lock); + SH_TAILQ_REMOVE(&sh_obj->holders, lp, links, + __db_lock); + lp->status = DB_LSTAT_FREE; + SH_TAILQ_INSERT_HEAD(<->region->free_locks, + lp, links, __db_lock); + } + + /* Now free the object. */ + __lock_freeobj(lt, sh_obj); + break; +#ifdef DEBUG + case DB_LOCK_DUMP: + /* Find the locker. */ + if ((ret = __lock_getobj(lt, locker, + NULL, DB_LOCK_LOCKER, &sh_locker)) != 0) + 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); + ret = EINVAL; + } + if (ret == 0) { + __lock_freeobj(lt, sh_locker); + lt->region->nlockers--; + } + break; +#endif + default: + ret = EINVAL; + break; + } + } + + if (lt->region->need_dd && lt->region->detect != DB_LOCK_NORUN) { + run_dd = 1; + lt->region->need_dd = 0; + } else + run_dd = 0; + + UNLOCK_LOCKREGION(lt); + + if (ret == 0 && run_dd) + lock_detect(lt, 0, lt->region->detect); + + if (elistp && ret != 0) + *elistp = &list[i - 1]; + return (ret); +} + +int +lock_get(lt, locker, flags, obj, lock_mode, lock) + DB_LOCKTAB *lt; + u_int32_t locker; + int flags; + const DBT *obj; + db_lockmode_t lock_mode; + DB_LOCK *lock; +{ + struct __db_lock *lockp; + int ret; + + /* Validate arguments. */ + if ((ret = + __db_fchk(lt->dbenv, "lock_get", flags, DB_LOCK_NOWAIT)) != 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++; + } + + UNLOCK_LOCKREGION(lt); + return (ret); +} + +int +lock_put(lt, lock) + DB_LOCKTAB *lt; + DB_LOCK lock; +{ + struct __db_lock *lockp; + int ret, run_dd; + + LOCK_LOCKREGION(lt); + + if ((ret = __lock_validate_region(lt)) != 0) + return (ret); + else { + lockp = OFFSET_TO_LOCK(lt, lock); + ret = __lock_put_internal(lt, lockp, 0); + } + + __lock_checklocker(lt, lockp, 0); + + if (lt->region->need_dd && lt->region->detect != DB_LOCK_NORUN) { + run_dd = 1; + lt->region->need_dd = 0; + } else + run_dd = 0; + + UNLOCK_LOCKREGION(lt); + + if (ret == 0 && run_dd) + lock_detect(lt, 0, lt->region->detect); + + return (ret); +} + +int +lock_close(lt) + DB_LOCKTAB *lt; +{ + int ret; + + if ((ret = __db_rclose(lt->dbenv, lt->fd, lt->region)) != 0) + return (ret); + + /* Free lock table. */ + free(lt); + return (0); +} + +int +lock_unlink(path, force, dbenv) + const char *path; + int force; + DB_ENV *dbenv; +{ + return (__db_runlink(dbenv, + DB_APP_NONE, path, DB_DEFAULT_LOCK_FILE, force)); +} + +/* + * XXX This looks like it could be void, but I'm leaving it returning + * an int because I think it will have to when we go through and add + * the appropriate error checking for the EINTR on mutexes. + */ +static int +__lock_put_internal(lt, lockp, do_all) + DB_LOCKTAB *lt; + struct __db_lock *lockp; + int do_all; +{ + struct __db_lock *lp_w, *lp_h, *next_waiter; + DB_LOCKOBJ *sh_obj; + int state_changed; + + if (lockp->refcount == 0 || (lockp->status != DB_LSTAT_HELD && + lockp->status != DB_LSTAT_WAITING) || lockp->obj == 0) { + __db_err(lt->dbenv, "lock_put: invalid lock %lu", + (u_long)((u_int8_t *)lockp - (u_int8_t *)lt->region)); + return (EINVAL); + } + + if (do_all) + lt->region->nreleases += lockp->refcount; + else + lt->region->nreleases++; + if (do_all == 0 && lockp->refcount > 1) { + lockp->refcount--; + return (0); + } + + /* Get the object associated with this lock. */ + sh_obj = (DB_LOCKOBJ *)((u_int8_t *)lockp + lockp->obj); + + /* Remove lock from locker list. */ + SH_LIST_REMOVE(lockp, locker_links, __db_lock); + + /* Remove this lock from its holders/waitlist. */ + if (lockp->status != DB_LSTAT_HELD) + __lock_remove_waiter(lt, sh_obj, lockp, DB_LSTAT_FREE); + 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->fd); + state_changed = 1; + } + + /* Check if object should be reclaimed. */ + if (SH_TAILQ_FIRST(&sh_obj->holders, __db_lock) == NULL) { + __db_hashremove_el(lt->hashtab, __db_lockobj, links, sh_obj, + lt->region->table_size, __lock_lhash); + __db_shalloc_free(lt->mem, SH_DBT_PTR(&sh_obj->lockobj)); + SH_TAILQ_INSERT_HEAD(<->region->free_objs, sh_obj, links, + __db_lockobj); + state_changed = 1; + } + + /* Free lock. */ + lockp->status = DB_LSTAT_FREE; + SH_TAILQ_INSERT_HEAD(<->region->free_locks, lockp, links, __db_lock); + + /* + * If we did not promote anyone; we need to run the deadlock + * detector again. + */ + if (state_changed == 0) + lt->region->need_dd = 1; + + return (0); +} + +static int +__lock_get_internal(lt, locker, flags, obj, lock_mode, lockp) + DB_LOCKTAB *lt; + u_int32_t locker; + int flags; + const DBT *obj; + db_lockmode_t lock_mode; + struct __db_lock **lockp; +{ + struct __db_lock *newl, *lp; + DB_LOCKOBJ *sh_obj, *sh_locker; + DB_LOCKREGION *lrp; + size_t newl_off; + int ret; + + ret = 0; + /* + * Check that lock mode is valid. + */ + + lrp = lt->region; + if ((u_int32_t)lock_mode >= lrp->nmodes) { + __db_err(lt->dbenv, + "lock_get: invalid lock mode %lu\n", (u_long)lock_mode); + return (EINVAL); + } + + /* Allocate a new lock. Optimize for the common case of a grant. */ + if ((newl = SH_TAILQ_FIRST(&lrp->free_locks, __db_lock)) == NULL) { + if ((ret = __lock_grow_region(lt, DB_LOCK_LOCK, 0)) != 0) + return (ret); + lrp = lt->region; + newl = SH_TAILQ_FIRST(&lrp->free_locks, __db_lock); + } + newl_off = LOCK_TO_OFFSET(lt, newl); + + /* Optimize for common case of granting a lock. */ + SH_TAILQ_REMOVE(&lrp->free_locks, newl, links, __db_lock); + + newl->mode = lock_mode; + newl->status = DB_LSTAT_HELD; + newl->holder = locker; + newl->refcount = 1; + + if ((ret = + __lock_getobj(lt, 0, (DBT *)obj, DB_LOCK_OBJTYPE, &sh_obj)) != 0) + return (ret); + + lrp = lt->region; /* getobj might have grown */ + newl = OFFSET_TO_LOCK(lt, newl_off); + + /* Now make new lock point to object */ + newl->obj = SH_PTR_TO_OFF(newl, sh_obj); + + /* + * 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. In case of conflict, we put the + * new lock on the end of the waiters list. + */ + for (lp = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock); + lp != NULL; + lp = SH_TAILQ_NEXT(lp, links, __db_lock)) { + if (CONFLICTS(lt, lp->mode, lock_mode) && + locker != lp->holder) + break; + else if (lp->holder == locker && lp->mode == lock_mode && + lp->status == DB_LSTAT_HELD) { + /* Lock is already held, just inc the ref count. */ + lp->refcount++; + SH_TAILQ_INSERT_HEAD(&lrp->free_locks, newl, links, + __db_lock); + *lockp = lp; + return (0); + } + } + + if (lp == NULL) + for (lp = SH_TAILQ_FIRST(&sh_obj->waiters, __db_lock); + lp != NULL; + lp = SH_TAILQ_NEXT(lp, links, __db_lock)) { + if (CONFLICTS(lt, lp->mode, lock_mode) && + locker != lp->holder) + break; + } + if (lp == NULL) + SH_TAILQ_INSERT_TAIL(&sh_obj->holders, newl, links); + else if (!(flags & DB_LOCK_NOWAIT)) + SH_TAILQ_INSERT_TAIL(&sh_obj->waiters, newl, links); + else { + /* Free the lock and return an error. */ + newl->status = DB_LSTAT_FREE; + SH_TAILQ_INSERT_HEAD(&lrp->free_locks, newl, links, __db_lock); + return (DB_LOCK_NOTGRANTED); + } + + /* + * 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->fd, + lt->dbenv == NULL ? NULL : lt->dbenv->db_yield); + + /* + * Now, insert the lock onto its locker's list. + */ + if ((ret = + __lock_getobj(lt, locker, NULL, DB_LOCK_LOCKER, &sh_locker)) != 0) + return (ret); + + lrp = lt->region; + SH_LIST_INSERT_HEAD(&sh_locker->heldby, newl, locker_links, __db_lock); + + if (lp != NULL) { + 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. + */ + if (lrp->detect == DB_LOCK_NORUN) + lt->region->need_dd = 1; + UNLOCK_LOCKREGION(lt); + + /* + * 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); + + (void)__db_mutex_lock(&newl->mutex, + lt->fd, lt->dbenv == NULL ? NULL : lt->dbenv->db_yield); + + LOCK_LOCKREGION(lt); + if (newl->status != DB_LSTAT_PENDING) { + /* Return to free list. */ + __lock_checklocker(lt, newl, 0); + SH_TAILQ_INSERT_HEAD(&lrp->free_locks, newl, links, + __db_lock); + switch (newl->status) { + case DB_LSTAT_ABORTED: + ret = DB_LOCK_DEADLOCK; + break; + case DB_LSTAT_NOGRANT: + ret = DB_LOCK_NOTGRANTED; + break; + default: + ret = EINVAL; + break; + } + newl->status = DB_LSTAT_FREE; + newl = NULL; + } else + newl->status = DB_LSTAT_HELD; + } + + *lockp = newl; + return (ret); +} + +/* + * This is called at every interface to verify if the region + * has changed size, and if so, to remap the region in and + * reset the process pointers. + */ +static int +__lock_validate_region(lt) + DB_LOCKTAB *lt; +{ + int ret; + + if (lt->reg_size == lt->region->hdr.size) + return (0); + + /* Grow the region. */ + if ((ret = __db_rremap(lt->dbenv, lt->region, + lt->reg_size, lt->region->hdr.size, lt->fd, <->region)) != 0) + return (ret); + + __lock_reset_region(lt); + + return (0); +} + +/* + * We have run out of space; time to grow the region. + */ +static int +__lock_grow_region(lt, which, howmuch) + DB_LOCKTAB *lt; + int which; + size_t howmuch; +{ + struct __db_lock *newl; + struct lock_header *lock_head; + struct obj_header *obj_head; + DB_LOCKOBJ *op; + DB_LOCKREGION *lrp; + float lock_ratio, obj_ratio; + size_t incr, oldsize, used; + u_int32_t i, newlocks, newmem, newobjs; + int ret, usedlocks, usedmem, usedobjs; + u_int8_t *curaddr; + + lrp = lt->region; + oldsize = lrp->hdr.size; + incr = lrp->increment; + + /* Figure out how much of each sort of space we have. */ + usedmem = lrp->mem_bytes - __db_shalloc_count(lt->mem); + usedobjs = lrp->numobjs - __lock_count_objs(lrp); + usedlocks = lrp->maxlocks - __lock_count_locks(lrp); + + /* + * Figure out what fraction of the used space belongs to each + * different type of "thing" in the region. Then partition the + * new space up according to this ratio. + */ + used = usedmem + + usedlocks * ALIGN(sizeof(struct __db_lock), MUTEX_ALIGNMENT) + + usedobjs * sizeof(DB_LOCKOBJ); + + lock_ratio = usedlocks * + ALIGN(sizeof(struct __db_lock), MUTEX_ALIGNMENT) / (float)used; + obj_ratio = usedobjs * sizeof(DB_LOCKOBJ) / (float)used; + + newlocks = (u_int32_t)(lock_ratio * + incr / ALIGN(sizeof(struct __db_lock), MUTEX_ALIGNMENT)); + newobjs = (u_int32_t)(obj_ratio * incr / sizeof(DB_LOCKOBJ)); + newmem = incr - + (newobjs * sizeof(DB_LOCKOBJ) + + newlocks * ALIGN(sizeof(struct __db_lock), MUTEX_ALIGNMENT)); + + /* + * Make sure we allocate enough memory for the object being + * requested. + */ + switch (which) { + case DB_LOCK_LOCK: + if (newlocks == 0) { + newlocks = 10; + incr += newlocks * sizeof(struct __db_lock); + } + break; + case DB_LOCK_OBJ: + if (newobjs == 0) { + newobjs = 10; + incr += newobjs * sizeof(DB_LOCKOBJ); + } + break; + case DB_LOCK_MEM: + if (newmem < howmuch * 2) { + incr += howmuch * 2 - newmem; + newmem = howmuch * 2; + } + break; + } + + newmem += ALIGN(incr, sizeof(size_t)) - incr; + incr = ALIGN(incr, sizeof(size_t)); + + /* + * Since we are going to be allocating locks at the beginning of the + * new chunk, we need to make sure that the chunk is MUTEX_ALIGNMENT + * aligned. We did not guarantee this when we created the region, so + * we may need to pad the old region by extra bytes to ensure this + * alignment. + */ + incr += ALIGN(oldsize, MUTEX_ALIGNMENT) - oldsize; + + __db_err(lt->dbenv, + "Growing lock region: %lu locks %lu objs %lu bytes", + (u_long)newlocks, (u_long)newobjs, (u_long)newmem); + + if ((ret = __db_rgrow(lt->dbenv, lt->fd, incr)) != 0) + return (ret); + if ((ret = __db_rremap(lt->dbenv, + lt->region, oldsize, oldsize + incr, lt->fd, <->region)) != 0) + return (ret); + __lock_reset_region(lt); + + /* Update region parameters. */ + lrp = lt->region; + lrp->increment = incr << 1; + lrp->maxlocks += newlocks; + lrp->numobjs += newobjs; + lrp->mem_bytes += newmem; + + curaddr = (u_int8_t *)lrp + oldsize; + curaddr = (u_int8_t *)ALIGNP(curaddr, MUTEX_ALIGNMENT); + + /* Put new locks onto the free list. */ + lock_head = &lrp->free_locks; + for (i = 0; i++ < newlocks; + curaddr += ALIGN(sizeof(struct __db_lock), MUTEX_ALIGNMENT)) { + newl = (struct __db_lock *)curaddr; + SH_TAILQ_INSERT_HEAD(lock_head, newl, links, __db_lock); + } + + /* Put new objects onto the free list. */ + obj_head = &lrp->free_objs; + for (i = 0; i++ < newobjs; curaddr += sizeof(DB_LOCKOBJ)) { + op = (DB_LOCKOBJ *)curaddr; + SH_TAILQ_INSERT_HEAD(obj_head, op, links, __db_lockobj); + } + + *((size_t *)curaddr) = newmem - sizeof(size_t); + curaddr += sizeof(size_t); + __db_shalloc_free(lt->mem, curaddr); + + return (0); +} + +#ifdef DEBUG +void +__lock_dump_region(lt, flags) + DB_LOCKTAB *lt; + unsigned long flags; +{ + struct __db_lock *lp; + DB_LOCKOBJ *op; + DB_LOCKREGION *lrp; + u_int32_t i, j; + + lrp = lt->region; + + printf("Lock region parameters\n"); + printf("%s:0x%x\t%s:%lu\t%s:%lu\t%s:%lu\n%s:%lu\t%s:%lu\t%s:%lu\t\n", + "magic ", lrp->magic, + "version ", (u_long)lrp->version, + "processes ", (u_long)lrp->hdr.refcnt, + "maxlocks ", (u_long)lrp->maxlocks, + "table size ", (u_long)lrp->table_size, + "nmodes ", (u_long)lrp->nmodes, + "numobjs ", (u_long)lrp->numobjs); + printf("%s:%lu\t%s:%lu\t%s:%lu\n%s:%lu\t%s:%lu\t%s:%lu\n", + "size ", (u_long)lrp->hdr.size, + "nlockers ", (u_long)lrp->nlockers, + "hash_off ", (u_long)lrp->hash_off, + "increment ", (u_long)lrp->increment, + "mem_off ", (u_long)lrp->mem_off, + "mem_bytes ", (u_long)lrp->mem_bytes); +#ifndef HAVE_SPINLOCKS + printf("Mutex: off %lu", (u_long)lrp->hdr.lock.off); +#endif +#ifdef MUTEX_STATISTICS + printf(" waits %lu nowaits %lu", + (u_long)lrp->hdr.lock.mutex_set_wait, + (u_long)lrp->hdr.lock.mutex_set_nowait); +#endif + printf("\n%s:%lu\t%s:%lu\t%s:%lu\t%s:%lu\n", + "nconflicts ", (u_long)lrp->nconflicts, + "nrequests ", (u_long)lrp->nrequests, + "nreleases ", (u_long)lrp->nreleases, + "ndeadlocks ", (u_long)lrp->ndeadlocks); + printf("need_dd %lu\n", (u_long)lrp->need_dd); + if (flags & LOCK_DEBUG_CONF) { + printf("\nConflict matrix\n"); + + for (i = 0; i < lrp->nmodes; i++) { + for (j = 0; j < lrp->nmodes; j++) + printf("%lu\t", + (u_long)lt->conflicts[i * lrp->nmodes + j]); + printf("\n"); + } + } + + for (i = 0; i < lrp->table_size; i++) { + op = SH_TAILQ_FIRST(<->hashtab[i], __db_lockobj); + if (op != NULL && flags & LOCK_DEBUG_BUCKET) + printf("Bucket %lu:\n", (unsigned long)i); + while (op != NULL) { + if (op->type == DB_LOCK_LOCKER && + flags & LOCK_DEBUG_LOCKERS) + __lock_dump_locker(lt, op); + else if (flags & LOCK_DEBUG_OBJECTS && + op->type == DB_LOCK_OBJTYPE) + __lock_dump_object(lt, op); + op = SH_TAILQ_NEXT(op, links, __db_lockobj); + } + } + + if (flags & LOCK_DEBUG_LOCK) { + printf("\nLock Free List\n"); + for (lp = SH_TAILQ_FIRST(&lrp->free_locks, __db_lock); + lp != NULL; + lp = SH_TAILQ_NEXT(lp, links, __db_lock)) { + printf("0x%x: %lu\t%lu\t%lu\t0x%x\n", (u_int)lp, + (u_long)lp->holder, (u_long)lp->mode, + (u_long)lp->status, (u_int)lp->obj); + } + } + + if (flags & LOCK_DEBUG_LOCK) { + printf("\nObject Free List\n"); + for (op = SH_TAILQ_FIRST(&lrp->free_objs, __db_lockobj); + op != NULL; + op = SH_TAILQ_NEXT(op, links, __db_lockobj)) + printf("0x%x\n", (u_int)op); + } + + if (flags & LOCK_DEBUG_MEM) { + printf("\nMemory Free List\n"); + __db_shalloc_dump(stdout, lt->mem); + } +} + +static void +__lock_dump_locker(lt, op) + DB_LOCKTAB *lt; + DB_LOCKOBJ *op; +{ + struct __db_lock *lp; + u_int32_t locker; + void *ptr; + + ptr = SH_DBT_PTR(&op->lockobj); + memcpy(&locker, ptr, sizeof(u_int32_t)); + printf("L %lu", (u_long)locker); + + lp = SH_LIST_FIRST(&op->heldby, __db_lock); + if (lp == NULL) { + printf("\n"); + return; + } + for (; lp != NULL; lp = SH_LIST_NEXT(lp, locker_links, __db_lock)) + __lock_printlock(lt, lp, 0); +} + +static void +__lock_dump_object(lt, op) + DB_LOCKTAB *lt; + DB_LOCKOBJ *op; +{ + struct __db_lock *lp; + u_int32_t j; + char *ptr; + + ptr = SH_DBT_PTR(&op->lockobj); + for (j = 0; j < op->lockobj.size; ptr++, j++) + printf("%c", (int)*ptr); + printf("\n"); + + printf("H:"); + for (lp = + SH_TAILQ_FIRST(&op->holders, __db_lock); + lp != NULL; + lp = SH_TAILQ_NEXT(lp, links, __db_lock)) + __lock_printlock(lt, lp, 0); + lp = SH_TAILQ_FIRST(&op->waiters, __db_lock); + if (lp != NULL) { + printf("\nW:"); + for (; lp != NULL; lp = SH_TAILQ_NEXT(lp, links, __db_lock)) + __lock_printlock(lt, lp, 0); + } +} + +int +__lock_is_locked(lt, locker, dbt, mode) + DB_LOCKTAB *lt; + u_int32_t locker; + DBT *dbt; + db_lockmode_t mode; +{ + struct __db_lock *lp; + DB_LOCKOBJ *sh_obj; + DB_LOCKREGION *lrp; + + lrp = lt->region; + + /* Look up the object in the hash table. */ + __db_hashlookup(lt->hashtab, __db_lockobj, links, + dbt, sh_obj, lrp->table_size, __lock_ohash, __lock_cmp); + if (sh_obj == NULL) + return (0); + + for (lp = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock); + lp != NULL; + lp = SH_TAILQ_FIRST(&sh_obj->holders, __db_lock)) { + if (lp->holder == locker && lp->mode == mode) + return (1); + } + + return (0); +} + +static void +__lock_printlock(lt, lp, ispgno) + DB_LOCKTAB *lt; + struct __db_lock *lp; + int ispgno; +{ + DB_LOCKOBJ *lockobj; + db_pgno_t pgno; + size_t obj; + u_int8_t *ptr; + char *mode, *stat; + + switch (lp->mode) { + case DB_LOCK_IREAD: + mode = "IREAD"; + break; + case DB_LOCK_IWR: + mode = "IWR"; + break; + case DB_LOCK_IWRITE: + mode = "IWRITE"; + break; + case DB_LOCK_NG: + mode = "NG"; + break; + case DB_LOCK_READ: + mode = "READ"; + break; + case DB_LOCK_WRITE: + mode = "WRITE"; + break; + default: + mode = "UNKNOWN"; + break; + } + switch (lp->status) { + case DB_LSTAT_ABORTED: + stat = "ABORT"; + break; + case DB_LSTAT_ERR: + stat = "ERROR"; + break; + case DB_LSTAT_FREE: + stat = "FREE"; + break; + case DB_LSTAT_HELD: + stat = "HELD"; + break; + case DB_LSTAT_NOGRANT: + stat = "NONE"; + break; + case DB_LSTAT_WAITING: + stat = "WAIT"; + break; + case DB_LSTAT_PENDING: + stat = "PENDING"; + break; + default: + stat = "UNKNOWN"; + break; + } + printf("\t%lu\t%s\t%lu\t%s\t", + (u_long)lp->holder, mode, (u_long)lp->refcount, stat); + + lockobj = (DB_LOCKOBJ *)((u_int8_t *)lp + lp->obj); + ptr = SH_DBT_PTR(&lockobj->lockobj); + if (ispgno) { + /* Assume this is a DBT lock. */ + memcpy(&pgno, ptr, sizeof(db_pgno_t)); + printf("page %lu\n", (u_long)pgno); + } else { + obj = (u_int8_t *)lp + lp->obj - (u_int8_t *)lt->region; + printf("0x%lx ", (u_long)obj); + __db_pr(ptr, lockobj->lockobj.size); + printf("\n"); + } +} + +#endif + +static int +__lock_count_locks(lrp) + DB_LOCKREGION *lrp; +{ + struct __db_lock *newl; + int count; + + count = 0; + for (newl = SH_TAILQ_FIRST(&lrp->free_locks, __db_lock); + newl != NULL; + newl = SH_TAILQ_NEXT(newl, links, __db_lock)) + count++; + + return (count); +} + +static int +__lock_count_objs(lrp) + DB_LOCKREGION *lrp; +{ + DB_LOCKOBJ *obj; + int count; + + count = 0; + for (obj = SH_TAILQ_FIRST(&lrp->free_objs, __db_lockobj); + obj != NULL; + obj = SH_TAILQ_NEXT(obj, links, __db_lockobj)) + count++; + + return (count); +} + +/* + * PUBLIC: int __lock_getobj __P((DB_LOCKTAB *, + * PUBLIC: u_int32_t, DBT *, u_int32_t type, DB_LOCKOBJ **)); + */ +int +__lock_getobj(lt, locker, dbt, type, objp) + DB_LOCKTAB *lt; + u_int32_t locker, type; + DBT *dbt; + DB_LOCKOBJ **objp; +{ + DB_LOCKREGION *lrp; + DB_LOCKOBJ *sh_obj; + u_int32_t obj_size; + int ret; + void *p, *src; + + lrp = lt->region; + + /* Look up the object in the hash table. */ + if (type == DB_LOCK_OBJTYPE) { + __db_hashlookup(lt->hashtab, __db_lockobj, links, dbt, sh_obj, + lrp->table_size, __lock_ohash, __lock_cmp); + obj_size = dbt->size; + } else { + __db_hashlookup(lt->hashtab, __db_lockobj, links, locker, + sh_obj, lrp->table_size, __lock_locker_hash, + __lock_locker_cmp); + obj_size = sizeof(locker); + } + + /* + * 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 new object and then insert it into hash table. */ + if ((sh_obj = SH_TAILQ_FIRST(&lrp->free_objs, __db_lockobj)) + == NULL) { + if ((ret = __lock_grow_region(lt, DB_LOCK_OBJ, 0)) != 0) + return (ret); + lrp = lt->region; + sh_obj = SH_TAILQ_FIRST(&lrp->free_objs, __db_lockobj); + } + if ((ret = __db_shalloc(lt->mem, obj_size, 0, &p)) != 0) { + if ((ret = __lock_grow_region(lt, + DB_LOCK_MEM, obj_size)) != 0) + return (ret); + lrp = lt->region; + /* Reacquire the head of the list. */ + sh_obj = SH_TAILQ_FIRST(&lrp->free_objs, __db_lockobj); + (void)__db_shalloc(lt->mem, obj_size, 0, &p); + } + sh_obj->type = type; + src = type == DB_LOCK_OBJTYPE ? dbt->data : (void *)&locker; + memcpy(p, src, obj_size); + SH_TAILQ_REMOVE(&lrp->free_objs, sh_obj, links, __db_lockobj); + + SH_TAILQ_INIT(&sh_obj->waiters); + if (type == DB_LOCK_LOCKER) + SH_LIST_INIT(&sh_obj->heldby); + else + SH_TAILQ_INIT(&sh_obj->holders); + sh_obj->lockobj.size = obj_size; + sh_obj->lockobj.off = SH_PTR_TO_OFF(&sh_obj->lockobj, p); + + __db_hashinsert(lt->hashtab, __db_lockobj, links, sh_obj, + lrp->table_size, __lock_lhash); + + if (type == DB_LOCK_LOCKER) + lrp->nlockers++; + } + + *objp = sh_obj; + return (0); +} + +/* + * 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. + */ +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; +{ + SH_TAILQ_REMOVE(&sh_obj->waiters, lockp, links, __db_lock); + lockp->status = status; + + /* Wake whoever is waiting on this lock. */ + (void)__db_mutex_unlock(&lockp->mutex, lt->fd); +} + +static void +__lock_freeobj(lt, obj) + DB_LOCKTAB *lt; + DB_LOCKOBJ *obj; +{ + __db_hashremove_el(lt->hashtab, __db_lockobj, links, + obj, lt->region->table_size, __lock_lhash); + __db_shalloc_free(lt->mem, SH_DBT_PTR(&obj->lockobj)); + SH_TAILQ_INSERT_HEAD(<->region->free_objs, obj, links, __db_lockobj); +} + +static void +__lock_checklocker(lt, lockp, do_remove) + DB_LOCKTAB *lt; + struct __db_lock *lockp; + int do_remove; +{ + DB_LOCKOBJ *sh_locker; + + if (do_remove) + SH_LIST_REMOVE(lockp, locker_links, __db_lock); + + /* if the locker list is NULL, free up the object. */ + if (__lock_getobj(lt, lockp->holder, NULL, DB_LOCK_LOCKER, &sh_locker) + == 0 && SH_LIST_FIRST(&sh_locker->heldby, __db_lock) == NULL) { + __lock_freeobj(lt, sh_locker); + lt->region->nlockers--; + } +} + +static void +__lock_reset_region(lt) + DB_LOCKTAB *lt; +{ + lt->conflicts = (u_int8_t *)lt->region + sizeof(DB_LOCKREGION); + lt->hashtab = + (DB_HASHTAB *)((u_int8_t *)lt->region + lt->region->hash_off); + lt->mem = (void *)((u_int8_t *)lt->region + lt->region->mem_off); + lt->reg_size = lt->region->hdr.size; +} |