dbreg_util.c

这是国外的resip协议栈

		    ndx, fname->meta_pgno, NULL, 0)) != 0)
			return (ret);

		*dbpp = dblp->dbentry[ndx].dbp;
		return (0);
	}

	/*
	 * Return DB_DELETED if the file has been deleted (it's not an error).
	 */
	if (dblp->dbentry[ndx].deleted) {
		ret = DB_DELETED;
		goto err;
	}

	/* It's an error if we don't have a corresponding writeable DB. */
	if ((*dbpp = dblp->dbentry[ndx].dbp) == NULL)
		ret = ENOENT;

err:	MUTEX_THREAD_UNLOCK(dbenv, dblp->mutexp);
	return (ret);
}

/*
 * __dbreg_id_to_fname --
 *	Traverse the shared-memory region looking for the entry that
 *	matches the passed dbreg id.  Returns 0 on success; -1 on error.
 *
 * PUBLIC: int __dbreg_id_to_fname __P((DB_LOG *, int32_t, int, FNAME **));
 */
int
__dbreg_id_to_fname(dblp, id, have_lock, fnamep)
	DB_LOG *dblp;
	int32_t id;
	int have_lock;
	FNAME **fnamep;
{
	DB_ENV *dbenv;
	FNAME *fnp;
	LOG *lp;
	int ret;

	dbenv = dblp->dbenv;
	lp = dblp->reginfo.primary;

	ret = -1;

	if (!have_lock)
		MUTEX_LOCK(dbenv, &lp->fq_mutex);
	for (fnp = SH_TAILQ_FIRST(&lp->fq, __fname);
	    fnp != NULL; fnp = SH_TAILQ_NEXT(fnp, q, __fname)) {
		if (fnp->id == id) {
			*fnamep = fnp;
			ret = 0;
			break;
		}
	}
	if (!have_lock)
		MUTEX_UNLOCK(dbenv, &lp->fq_mutex);

	return (ret);
}
/*
 * __dbreg_fid_to_fname --
 *	Traverse the shared-memory region looking for the entry that
 *	matches the passed file unique id.  Returns 0 on success; -1 on error.
 *
 * PUBLIC: int __dbreg_fid_to_fname __P((DB_LOG *, u_int8_t *, int, FNAME **));
 */
int
__dbreg_fid_to_fname(dblp, fid, have_lock, fnamep)
	DB_LOG *dblp;
	u_int8_t *fid;
	int have_lock;
	FNAME **fnamep;
{
	DB_ENV *dbenv;
	FNAME *fnp;
	LOG *lp;
	int ret;

	dbenv = dblp->dbenv;
	lp = dblp->reginfo.primary;

	ret = -1;

	if (!have_lock)
		MUTEX_LOCK(dbenv, &lp->fq_mutex);
	for (fnp = SH_TAILQ_FIRST(&lp->fq, __fname);
	    fnp != NULL; fnp = SH_TAILQ_NEXT(fnp, q, __fname)) {
		if (memcmp(fnp->ufid, fid, DB_FILE_ID_LEN) == 0) {
			*fnamep = fnp;
			ret = 0;
			break;
		}
	}
	if (!have_lock)
		MUTEX_UNLOCK(dbenv, &lp->fq_mutex);

	return (ret);
}

/*
 * __dbreg_get_name
 *
 * Interface to get name of registered files.  This is mainly diagnostic
 * and the name passed could be transient unless there is something
 * ensuring that the file cannot be closed.
 *
 * PUBLIC: int __dbreg_get_name __P((DB_ENV *, u_int8_t *, char **));
 */
int
__dbreg_get_name(dbenv, fid, namep)
	DB_ENV *dbenv;
	u_int8_t *fid;
	char **namep;
{
	DB_LOG *dblp;
	FNAME *fnp;

	dblp = dbenv->lg_handle;

	if (dblp != NULL && __dbreg_fid_to_fname(dblp, fid, 0, &fnp) == 0) {
		*namep = R_ADDR(&dblp->reginfo, fnp->name_off);
		return (0);
	}

	return (-1);
}

/*
 * __dbreg_do_open --
 *	Open files referenced in the log.  This is the part of the open that
 * is not protected by the thread mutex.
 * PUBLIC: int __dbreg_do_open __P((DB_ENV *, DB_TXN *, DB_LOG *, u_int8_t *,
 * PUBLIC:     char *, DBTYPE, int32_t, db_pgno_t, void *, u_int32_t));
 */
int
__dbreg_do_open(dbenv,
    txn, lp, uid, name, ftype, ndx, meta_pgno, info, id)
	DB_ENV *dbenv;
	DB_TXN *txn;
	DB_LOG *lp;
	u_int8_t *uid;
	char *name;
	DBTYPE ftype;
	int32_t ndx;
	db_pgno_t meta_pgno;
	void *info;
	u_int32_t id;
{
	DB *dbp;
	u_int32_t cstat, ret_stat;
	int ret;

	if ((ret = db_create(&dbp, lp->dbenv, 0)) != 0)
		return (ret);

	/*
	 * We can open files under a number of different scenarios.
	 * First, we can open a file during a normal txn_abort, if that file
	 * was opened and closed during the transaction (as is the master
	 * database of a sub-database).
	 * Second, we might be aborting a transaction in XA and not have
	 * it open in the process that is actually doing the abort.
	 * Third, we might be in recovery.
	 * In case 3, there is no locking, so there is no issue.
	 * In cases 1 and 2, we are guaranteed to already hold any locks
	 * that we need, since we're still in the same transaction, so by
	 * setting DB_AM_RECOVER, we guarantee that we don't log and that
	 * we don't try to acquire locks on behalf of a different locker id.
	 */
	F_SET(dbp, DB_AM_RECOVER);
	if (meta_pgno != PGNO_BASE_MD) {
		memcpy(dbp->fileid, uid, DB_FILE_ID_LEN);
		dbp->meta_pgno = meta_pgno;
	}
	if ((ret = __db_open(dbp, txn, name, NULL,
	    ftype, DB_ODDFILESIZE, __db_omode("rw----"), meta_pgno)) == 0) {

		/*
		 * Verify that we are opening the same file that we were
		 * referring to when we wrote this log record.
		 */
		if ((meta_pgno != PGNO_BASE_MD &&
		    __dbreg_check_master(dbenv, uid, name) != 0) ||
		    memcmp(uid, dbp->fileid, DB_FILE_ID_LEN) != 0)
			cstat = TXN_IGNORE;
		else
			cstat = TXN_EXPECTED;

		/* Assign the specific dbreg id to this dbp. */
		if ((ret = __dbreg_assign_id(dbp, ndx)) != 0)
			goto err;

		/*
		 * If we successfully opened this file, then we need to
		 * convey that information to the txnlist so that we
		 * know how to handle the subtransaction that created
		 * the file system object.
		 */
		if (id != TXN_INVALID)
			ret = __db_txnlist_update(dbenv,
			    info, id, cstat, NULL, &ret_stat, 1);

err:		if (cstat == TXN_IGNORE)
			goto not_right;
		return (ret);
	} else if (ret == ENOENT) {
		/* Record that the open failed in the txnlist. */
		if (id != TXN_INVALID)
			ret = __db_txnlist_update(dbenv, info,
			    id, TXN_UNEXPECTED, NULL, &ret_stat, 1);
	}
not_right:
	(void)__db_close(dbp, NULL, DB_NOSYNC);
	/* Add this file as deleted. */
	(void)__dbreg_add_dbentry(dbenv, lp, NULL, ndx);
	return (ret);
}

static int
__dbreg_check_master(dbenv, uid, name)
	DB_ENV *dbenv;
	u_int8_t *uid;
	char *name;
{
	DB *dbp;
	int ret;

	ret = 0;
	if ((ret = db_create(&dbp, dbenv, 0)) != 0)
		return (ret);
	F_SET(dbp, DB_AM_RECOVER);
	ret = __db_open(dbp,
	    NULL, name, NULL, DB_BTREE, 0, __db_omode("rw----"), PGNO_BASE_MD);

	if (ret == 0 && memcmp(uid, dbp->fileid, DB_FILE_ID_LEN) != 0)
		ret = EINVAL;

	(void)__db_close(dbp, NULL, 0);
	return (ret);
}

/*
 * __dbreg_lazy_id --
 *	When a replication client gets upgraded to being a replication master,
 * it may have database handles open that have not been assigned an ID, but
 * which have become legal to use for logging.
 *
 *	This function lazily allocates a new ID for such a function, in a
 * new transaction created for the purpose.  We need to do this in a new
 * transaction because we definitely wish to commit the dbreg_register, but
 * at this point we have no way of knowing whether the log record that incited
 * us to call this will be part of a committed transaction.
 *
 * PUBLIC: int __dbreg_lazy_id __P((DB *));
 */
int
__dbreg_lazy_id(dbp)
	DB *dbp;
{
	DB_ENV *dbenv;
	DB_LOG *dblp;
	DB_TXN *txn;
	FNAME *fnp;
	LOG *lp;
	int32_t id;
	int ret;

	dbenv = dbp->dbenv;

	DB_ASSERT(IS_REP_MASTER(dbenv));

	dbenv = dbp->dbenv;
	dblp = dbenv->lg_handle;
	lp = dblp->reginfo.primary;
	fnp = dbp->log_filename;

	/* The fq_mutex protects the FNAME list and id management. */
	MUTEX_LOCK(dbenv, &lp->fq_mutex);
	if (fnp->id != DB_LOGFILEID_INVALID) {
		MUTEX_UNLOCK(dbenv, &lp->fq_mutex);
		return (0);
	}
	id = DB_LOGFILEID_INVALID;
	if ((ret = __txn_begin(dbenv, NULL, &txn, 0)) != 0)
		goto err;

	if ((ret = __dbreg_get_id(dbp, txn, &id)) != 0) {
		(void)__txn_abort(txn);
		goto err;
	}

	if ((ret = __txn_commit(txn, DB_TXN_NOSYNC)) != 0)
		goto err;

	/*
	 * All DB related logging routines check the id value *without*
	 * holding the fq_mutex to know whether we need to call
	 * dbreg_lazy_id to begin with.  We must set the ID after a
	 * *successful* commit so that there is no possibility of a second
	 * modification call finding a valid ID in the dbp before the
	 * dbreg_register and commit records are in the log.
	 * If there was an error, then we call __dbreg_revoke_id to
	 * remove the entry from the lists.
	 */
	fnp->id = id;
err:
	if (ret != 0 && id != DB_LOGFILEID_INVALID)
		(void)__dbreg_revoke_id(dbp, 1, id);
	MUTEX_UNLOCK(dbenv, &lp->fq_mutex);
	return (ret);
}