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glibc/db2/lock/lock.c

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/*-
* 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)), &lt->fd, &lt->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(&lt->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(&lt->region->free_objs, sh_obj, links,
__db_lockobj);
state_changed = 1;
}
/* Free lock. */
lockp->status = DB_LSTAT_FREE;
SH_TAILQ_INSERT_HEAD(&lt->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, &lt->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, &lt->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(&lt->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(&lt->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;
}
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