txn.c

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		F_CLR(txnp, TXN_SYNC);
		F_SET(txnp, TXN_NOSYNC);
	}
	if (LF_ISSET(DB_TXN_SYNC)) {
		F_CLR(txnp, TXN_NOSYNC);
		F_SET(txnp, TXN_SYNC);
	}

	/*
	 * Commit any unresolved children.  If anyone fails to commit,
	 * then try to abort the rest of the kids and then abort the parent.
	 * Abort should never fail; if it does, we bail out immediately.
	 */
	while ((kid = TAILQ_FIRST(&txnp->kids)) != NULL)
		if ((ret = kid->commit(kid, flags)) != 0)
			while ((kid = TAILQ_FIRST(&txnp->kids)) != NULL)
				if ((t_ret = kid->abort(kid)) != 0)
					return (__db_panic(dbenv, t_ret));

	/*
	 * Process any aborted pages from our children.
	 * We delay putting pages on the free list that are newly
	 * allocated and then aborted so that we can undo other
	 * allocations, if necessary, without worrying about
	 * these pages which were not on the free list before.
	 */
	if (txnp->txn_list != NULL) {
		t_ret = __db_do_the_limbo(dbenv, NULL, txnp, txnp->txn_list);
		__db_txnlist_end(dbenv, txnp->txn_list);
		txnp->txn_list = NULL;
		if (t_ret != 0 && ret == 0)
			ret = t_ret;
	}

	if (ret != 0)
		goto err;

	/*
	 * If there are any log records, write a log record and sync the log,
	 * else do no log writes.  If the commit is for a child transaction,
	 * we do not need to commit the child synchronously since it may still
	 * abort (if its parent aborts), and otherwise its parent or ultimate
	 * ancestor will write synchronously.
	 */
	if (DBENV_LOGGING(dbenv) && !IS_ZERO_LSN(txnp->last_lsn)) {
		if (txnp->parent == NULL) {
			/*
			 * We are about to free all the read locks
			 * for this transaction below.  Some of those
			 * locks might be handle locks which should
			 * not be freed, because they will be freed
			 * when the handle is closed.  Check the
			 * events and preprocess any trades now so
			 * that we don't release the locks below.
			 */
			if ((ret = __txn_doevents(dbenv, txnp, 0, 1)) != 0)
				goto err;
			request.op = DB_LOCK_PUT_READ;
			if (LOCKING_ON(dbenv) && (ret = dbenv->lock_vec(
			   dbenv, txnp->txnid, 0, &request, 1, NULL)) != 0)
				goto err;

			SET_LOG_FLAGS(dbenv, txnp, lflags);
			if ((ret = __txn_regop_log(dbenv,
			    txnp, &txnp->last_lsn, lflags,
			    TXN_COMMIT, (int32_t)time(NULL))) != 0)
				goto err;
		} else {
			/* Log the commit in the parent! */
			if ((ret = __txn_child_log(dbenv,
			    txnp->parent, &txnp->parent->last_lsn,
			    0, txnp->txnid, &txnp->last_lsn)) != 0) {
				goto err;
			}

			F_SET(txnp->parent, TXN_CHILDCOMMIT);
		}
	}

	/* This is OK because __txn_end can only fail with a panic. */
	return (__txn_end(txnp, 1));

err:	/*
	 * If we are prepared, then we "must" be able to commit.  We
	 * panic here because even though the coordinator might be
	 * able to retry it is not clear it would know to do that.
	 * Otherwise  we'll try to abort.  If that is successful,
	 * then we return whatever was in ret (i.e., the reason we failed).
	 * If the abort was unsuccessful, then abort probably returned
	 * DB_RUNRECOVERY and we need to propagate that up.
	 */
	if (td->status == TXN_PREPARED)
		return (__db_panic(dbenv, ret));
		
	if ((t_ret = txnp->abort(txnp)) != 0)
		ret = t_ret;
	return (ret);
}

/*
 * __txn_abort --
 *	Abort a transaction.
 *
 * PUBLIC: int __txn_abort __P((DB_TXN *));
 */
int
__txn_abort(txnp)
	DB_TXN *txnp;
{
	DB_ENV *dbenv;
	DB_LOCKREQ request;
	DB_TXN *kid;
	TXN_DETAIL *td;
	u_int32_t lflags;
	int ret;

	dbenv = txnp->mgrp->dbenv;

	PANIC_CHECK(dbenv);

	/* Ensure that abort always fails fatally. */
	if ((ret = __txn_isvalid(txnp, &td, TXN_OP_ABORT)) != 0)
		return (__db_panic(dbenv, ret));

	/*
	 * Try to abort any unresolved children.
	 *
	 * Abort either succeeds or panics the region.  As soon as we
	 * see any failure, we just get out of here and return the panic
	 * up.
	 */
	while ((kid = TAILQ_FIRST(&txnp->kids)) != NULL)
		if ((ret = kid->abort(kid)) != 0)
			return (ret);

	if (LOCKING_ON(dbenv)) {
		/*
		 * We are about to free all the read locks for this transaction
		 * below.  Some of those locks might be handle locks which
		 * should not be freed, because they will be freed when the
		 * handle is closed.  Check the events and preprocess any
		 * trades now so that we don't release the locks below.
		 */
		if ((ret = __txn_doevents(dbenv, txnp, 0, 1)) != 0)
			return (__db_panic(dbenv, ret));

		/* Turn off timeouts. */
		if ((ret = __lock_set_timeout(dbenv,
		    txnp->txnid, 0, DB_SET_TXN_TIMEOUT)) != 0)
			return (__db_panic(dbenv, ret));

		if ((ret = __lock_set_timeout(dbenv,
		    txnp->txnid, 0, DB_SET_LOCK_TIMEOUT)) != 0)
			return (__db_panic(dbenv, ret));

		request.op = DB_LOCK_UPGRADE_WRITE;
		if ((ret = dbenv->lock_vec(
		    dbenv, txnp->txnid, 0, &request, 1, NULL)) != 0)
			return (__db_panic(dbenv, ret));
	}
	if ((ret = __txn_undo(txnp)) != 0)
		return (__db_panic(dbenv, ret));

	/*
	 * Normally, we do not need to log aborts.  However, if we
	 * are a distributed transaction (i.e., we have a prepare),
	 * then we log the abort so we know that this transaction
	 * was actually completed.
	 */
	SET_LOG_FLAGS(dbenv, txnp, lflags);
	if (DBENV_LOGGING(dbenv) && td->status == TXN_PREPARED &&
	    (ret = __txn_regop_log(dbenv, txnp, &txnp->last_lsn,
	    lflags, TXN_ABORT, (int32_t)time(NULL))) != 0)
		return (__db_panic(dbenv, ret));

	/* __txn_end always panics if it errors, so pass the return along. */
	return (__txn_end(txnp, 0));
}

/*
 * __txn_discard --
 *	Free the per-process resources associated with this txn handle.
 *
 * PUBLIC: int __txn_discard __P((DB_TXN *, u_int32_t flags));
 */
int
__txn_discard(txnp, flags)
	DB_TXN *txnp;
	u_int32_t flags;
{
	DB_ENV *dbenv;
	DB_TXN *freep;
	TXN_DETAIL *td;
	int ret;

	COMPQUIET(flags, 0);

	dbenv = txnp->mgrp->dbenv;
	freep = NULL;

	PANIC_CHECK(dbenv);

	if ((ret = __txn_isvalid(txnp, &td, TXN_OP_DISCARD)) != 0)
		return (ret);

	/* Should be no children. */
	DB_ASSERT(TAILQ_FIRST(&txnp->kids) == NULL);
	DB_ASSERT(F_ISSET(td, TXN_RESTORED));

	/* Free the space. */
	MUTEX_THREAD_LOCK(dbenv, txnp->mgrp->mutexp);
	txnp->mgrp->n_discards++;
	if (F_ISSET(txnp, TXN_MALLOC)) {
		TAILQ_REMOVE(&txnp->mgrp->txn_chain, txnp, links);
		freep = txnp;
	}
	MUTEX_THREAD_UNLOCK(dbenv, txnp->mgrp->mutexp);
	if (freep != NULL)
		__os_free(dbenv, freep);

	return (0);
}

/*
 * __txn_prepare --
 *	Flush the log so a future commit is guaranteed to succeed.
 *
 * PUBLIC: int __txn_prepare __P((DB_TXN *, u_int8_t *));
 */
int
__txn_prepare(txnp, gid)
	DB_TXN *txnp;
	u_int8_t *gid;
{
	DBT xid;
	DB_ENV *dbenv;
	DB_TXN *kid;
	TXN_DETAIL *td;
	u_int32_t lflags;
	int ret;

	dbenv = txnp->mgrp->dbenv;

	PANIC_CHECK(dbenv);

	if ((ret = __txn_isvalid(txnp, &td, TXN_OP_PREPARE)) != 0)
		return (ret);

	/* Commit any unresolved children. */
	while ((kid = TAILQ_FIRST(&txnp->kids)) != NULL)
		if ((ret = kid->commit(kid, DB_TXN_NOSYNC)) != 0)
			return (ret);

	/*
	 * In XA, the global transaction ID in the txn_detail structure is
	 * already set; in a non-XA environment, we must set it here.  XA
	 * requires that the transaction be either ENDED or SUSPENDED when
	 * prepare is called, so we know that if the xa_status isn't in one
	 * of those states, then we are calling prepare directly and we need
	 * to fill in the td->xid.
	 */
	if (DBENV_LOGGING(dbenv)) {
		memset(&xid, 0, sizeof(xid));
		if (td->xa_status != TXN_XA_ENDED &&
		    td->xa_status != TXN_XA_SUSPENDED)
			/* Regular prepare; fill in the gid. */
			memcpy(td->xid, gid, sizeof(td->xid));

		xid.size = sizeof(td->xid);
		xid.data = td->xid;

		SET_LOG_FLAGS(dbenv, txnp, lflags);
		if ((ret = __txn_xa_regop_log(dbenv, txnp, &txnp->last_lsn,
		    lflags, TXN_PREPARE, &xid, td->format, td->gtrid, td->bqual,
		    &td->begin_lsn)) != 0) {
			__db_err(dbenv, "DB_TXN->prepare: log_write failed %s",
			    db_strerror(ret));
			return (ret);
		}
	}

	MUTEX_THREAD_LOCK(dbenv, txnp->mgrp->mutexp);
	td->status = TXN_PREPARED;
	MUTEX_THREAD_UNLOCK(dbenv, txnp->mgrp->mutexp);
	return (0);
}

/*
 * __txn_id --
 *	Return the transaction ID.
 *
 * PUBLIC: u_int32_t __txn_id __P((DB_TXN *));
 */
u_int32_t
__txn_id(txnp)
	DB_TXN *txnp;
{
	return (txnp->txnid);
}

/*
 * __txn_set_timeout --
 *	Set timeout values in the txn structure.
 */
static int
__txn_set_timeout(txnp, timeout, op)
	DB_TXN *txnp;
	db_timeout_t timeout;
	u_int32_t op;
{
	if (op != DB_SET_TXN_TIMEOUT &&  op != DB_SET_LOCK_TIMEOUT)
		return (__db_ferr(txnp->mgrp->dbenv, "DB_TXN->set_timeout", 0));

	return (__lock_set_timeout(
	    txnp->mgrp->dbenv, txnp->txnid, timeout, op));
}

/*
 * __txn_isvalid --
 *	Return 0 if the txnp is reasonable, otherwise panic.
 */
static int
__txn_isvalid(txnp, tdp, op)
	const DB_TXN *txnp;
	TXN_DETAIL **tdp;
	txnop_t op;
{
	DB_TXNMGR *mgrp;
	DB_TXNREGION *region;
	TXN_DETAIL *tp;

	mgrp = txnp->mgrp;
	region = mgrp->reginfo.primary;

	/* Check for recovery. */
	if (!F_ISSET(txnp, TXN_COMPENSATE) &&
	    F_ISSET(region, TXN_IN_RECOVERY)) {
		__db_err(mgrp->dbenv,
		    "operation not permitted during recovery");
		goto err;
	}

	/* Check for live cursors. */
	if (txnp->cursors != 0) {
		__db_err(mgrp->dbenv, "transaction has active cursors");
		goto err;
	}

	/* Check transaction's state. */
	tp = (TXN_DETAIL *)R_ADDR(&mgrp->reginfo, txnp->off);
	if (tdp != NULL)
		*tdp = tp;

	/* Handle any operation specific checks. */
	switch (op) {
	case TXN_OP_DISCARD:
		/*
		 * Since we're just tossing the per-process space; there are
		 * a lot of problems with the transaction that we can tolerate.
		 */

		/* Transaction is already been reused. */
		if (txnp->txnid != tp->txnid)
			return (0);

		/* What we've got had better be a restored transaction. */
		if (!F_ISSET(tp, TXN_RESTORED)) {
			__db_err(mgrp->dbenv, "not a restored transaction");
			return (__db_panic(mgrp->dbenv, EINVAL));
		}

		return (0);
	case TXN_OP_PREPARE:
		if (txnp->parent != NULL) {
			/*
			 * This is not fatal, because you could imagine an
			 * application that simply prepares everybody because
			 * it doesn't distinguish between children and parents.
			 * I'm not arguing this is good, but I could imagine
			 * someone doing it.
			 */
			__db_err(mgrp->dbenv,
			    "Prepare disallowed on child transactions");
			return (EINVAL);
		}
		break;
	case TXN_OP_ABORT:
	case TXN_OP_COMMIT:
	default:
		break;
	}

	switch (tp->status) {
	case TXN_PREPARED:
		if (op == TXN_OP_PREPARE) {
			__db_err(mgrp->dbenv, "transaction already prepared");
			/*
			 * Txn_prepare doesn't blow away the user handle, so
			 * in this case, give the user the opportunity to
			 * abort or commit.
			 */
			return (EINVAL);
		}
		break;
	case TXN_RUNNING:
		break;
	case TXN_ABORTED:
	case TXN_COMMITTED:
	default:
		__db_err(mgrp->dbenv, "transaction already %s",
		    tp->status == TXN_COMMITTED ? "committed" : "aborted");
		goto err;
	}

	return (0);

err:	/*
	 * If there's a serious problem with the transaction, panic.  TXN
	 * handles are dead by definition when we return, and if you use
	 * a cursor you forgot to close, we have no idea what will happen.
	 */
	return (__db_panic(mgrp->dbenv, EINVAL));
}

/*
 * __txn_end --
 *	Internal transaction end routine.
 */
static int
__txn_end(txnp, is_commit)
	DB_TXN *txnp;
	int is_commit;
{
	DB_ENV *dbenv;
	DB_LOCKREQ request;
	DB_TXNMGR *mgr;
	DB_TXNREGION *region;
	TXN_DETAIL *tp;
	int do_closefiles, ret;

	mgr = txnp->mgrp;
	dbenv = mgr->dbenv;
	region = mgr->reginfo.primary;
	do_closefiles = 0;

	/* Process commit events. */
	if ((ret = __txn_doevents(dbenv, txnp, is_commit, 0)) != 0)
		return (__db_panic(dbenv, ret));

	/* Release the locks. */
	request.op = txnp->parent == NULL ||
	    is_commit == 0 ? DB_LOCK_PUT_ALL : DB_LOCK_INHERIT;

	/*
	 * __txn_end cannot return an simple error, we MUST return
	 * success/failure from commit or abort, ignoring any internal
	 * errors.  So, we panic if something goes wrong.  We can't
	 * deadlock here because we're not acquiring any new locks,
	 * so DB_LOCK_DEADLOCK is just as fatal as any other error.
	 */
	if (LOCKING_ON(dbenv) && (ret = dbenv->lock_vec(
	    dbenv, txnp->txnid, DB_LOCK_FREE_LOCKER, &request, 1, NULL)) != 0)
		return (__db_panic(dbenv, ret));

	/* End the transaction. */
	R_LOCK(dbenv, &mgr->reginfo);

	tp = (TXN_DETAIL *)R_ADDR(&mgr->reginfo, txnp->off);
	SH_TAILQ_REMOVE(&region->active_txn, tp, links, __txn_detail);
	if (F_ISSET(tp, TXN_RESTORED)) {
		region->stat.st_nrestores--;
		do_closefiles = region->stat.st_nrestores == 0;
	}

	__db_shalloc_free(mgr->reginfo.addr, tp);

	if (is_commit)