#include <db.h>

int
DB_ENV->set_tas_spins(DB_ENV *dbenv, u_int32_t tas_spins);

Description

Specify that test-and-set mutexes should spin tas_spins times without blocking. The value defaults to 1 on uniprocessor systems and to 50 times the number of processors on multiprocessor systems.

The DB_ENV->set_tas_spins interface affects the entire application, not a single database or database environment.

Although the DB_ENV->set_tas_spins interface may be used to configure Berkeley DB at any time during the life of the application, it should normally be called before making any calls to the db_env_create or db_create functions.

The DB_ENV->set_tas_spins function returns a non-zero error value on failure and 0 on success.

The database environment's test-and-set spin count may also be set using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "set_tas_spins", one or more whitespace characters, and the number of spins. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

Errors

The DB_ENV->set_tas_spins function may fail and return a non-zero error for the following conditions:

EINVAL

An invalid flag value or parameter was specified.

The DB_ENV->set_tas_spins function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB_ENV->set_tas_spins function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

See Also