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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2005, 2012 Oracle and/or its affiliates. All rights reserved.
*
* $Id$
*/
#include "db_config.h"
#include "db_int.h"
#include "dbinc/lock.h"
#include "dbinc/txn.h"
/*
* __lock_failchk --
* Check for locks held by dead threads of control and release
* read locks. If any write locks were held by dead non-trasnactional
* lockers then we must abort and run recovery. Otherwise we release
* read locks for lockers owned by dead threads. Write locks for
* dead transactional lockers will be freed when we abort the transaction.
*
* PUBLIC: int __lock_failchk __P((ENV *));
*/
int
__lock_failchk(env)
ENV *env;
{
DB_ENV *dbenv;
DB_LOCKER *lip;
DB_LOCKREGION *lrp;
DB_LOCKREQ request;
DB_LOCKTAB *lt;
u_int32_t i;
int ret;
char buf[DB_THREADID_STRLEN];
dbenv = env->dbenv;
lt = env->lk_handle;
lrp = lt->reginfo.primary;
retry: LOCK_LOCKERS(env, lrp);
ret = 0;
for (i = 0; i < lrp->locker_t_size; i++)
SH_TAILQ_FOREACH(lip, <->locker_tab[i], links, __db_locker) {
/*
* If the locker is transactional, we can ignore it if
* it has no read locks or has no locks at all. Check
* the heldby list rather then nlocks since a lock may
* be PENDING. __txn_failchk aborts any transactional
* lockers. Non-transactional lockers progress to
* is_alive test.
*/
if ((lip->id >= TXN_MINIMUM) &&
(SH_LIST_EMPTY(&lip->heldby) ||
lip->nlocks == lip->nwrites))
continue;
/* If the locker is still alive, it's not a problem. */
if (dbenv->is_alive(dbenv, lip->pid, lip->tid,
F_ISSET(lip, DB_LOCKER_HANDLE_LOCKER) ?
DB_MUTEX_PROCESS_ONLY : 0))
continue;
/*
* We can only deal with read locks. If a
* non-transactional locker holds write locks we
* have to assume a Berkeley DB operation was
* interrupted with only 1-of-N pages modified.
*/
if (lip->id < TXN_MINIMUM && lip->nwrites != 0) {
ret = __db_failed(env, DB_STR_A("2052",
"locker has write locks", ""),
lip->pid, lip->tid);
break;
}
/*
* Discard the locker and its read locks.
*/
if (!SH_LIST_EMPTY(&lip->heldby)) {
__db_msg(env, DB_STR_A("2053",
"Freeing read locks for locker %#lx: %s",
"%#lx %s"), (u_long)lip->id,
dbenv->thread_id_string(
dbenv, lip->pid, lip->tid, buf));
UNLOCK_LOCKERS(env, lrp);
memset(&request, 0, sizeof(request));
request.op = DB_LOCK_PUT_READ;
if ((ret = __lock_vec(env,
lip, 0, &request, 1, NULL)) != 0)
return (ret);
}
else
UNLOCK_LOCKERS(env, lrp);
/*
* This locker is most likely referenced by a cursor
* which is owned by a dead thread. Normally the
* cursor would be available for other threads
* but we assume the dead thread will never release
* it.
*/
if (lip->id < TXN_MINIMUM &&
(ret = __lock_freelocker(lt, lip)) != 0)
return (ret);
goto retry;
}
UNLOCK_LOCKERS(env, lrp);
return (ret);
}
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