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Berkeley DB: db_env_set_tas_spins
db_env_set_tas_spins
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#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.
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