# db_env_set_tas_spins

`

###

    #include <db.h>

    int
    db_env_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 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

db_env_create, DB_ENV->close, DB_ENV->err, DB_ENV->errx DB_ENV->open, DB_ENV->remove, DB_ENV->set_alloc, DB_ENV->set_cachesize, DB_ENV->set_data_dir, DB_ENV->set_errcall, DB_ENV->set_errfile, DB_ENV->set_errpfx, DB_ENV->set_feedback, DB_ENV->set_flags, DB_ENV->set_mutexlocks, db_env_set_pageyield, DB_ENV->set_paniccall, db_env_set_panicstate, DB_ENV->set_recovery_init, DB_ENV->set_rpc_server, db_env_set_region_init, DB_ENV->set_shm_key, db_env_set_tas_spins, DB_ENV->set_tmp_dir, DB_ENV->set_verbose, db_strerror and db_version.`

Copyright Sleepycat Software