# DbEnv::set_tas_spins

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    #include <db_cxx.h>

    static int
    DbEnv::set_tas_spins(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 DbEnv::set_tas_spins interface affects the entire application, not a single database or database environment.

Although the DbEnv::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 methods.

The DbEnv::set_tas_spins method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 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 DbEnv::set_tas_spins method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

The DbEnv::set_tas_spins method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the DbEnv::set_tas_spins method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

# Class

DbEnv

# See Also

DbEnv::close, DbEnv::err, DbEnv::errx DbEnv::open, DbEnv::remove, DbEnv::set_alloc, DbEnv::set_cachesize, DbEnv::set_data_dir, DbEnv::set_errcall, DbEnv::set_errfile, DbEnv::set_error_stream, DbEnv::set_errpfx, DbEnv::set_feedback, DbEnv::set_flags, DbEnv::set_paniccall, DbEnv::set_recovery_init, DbEnv::set_rpc_server, DbEnv::set_shm_key, DbEnv::set_tas_spins, DbEnv::set_tmp_dir, DbEnv::set_timeout, DbEnv::set_verbose, DbEnv::strerror and DbEnv::version.`

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