Berkeley DB: DbEnv::mutex_set_tas_spins
Description: Berkeley DB: An embedded database programmatic toolkit.
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### DbEnv::mutex_set_tas_spins |

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    #include <db_cxx.h>

    int
    DbEnv::mutex_set_tas_spins(u_int32_t tas_spins);

    int
    DbEnv::mutex_get_tas_spins(u_int32_t *, tas_spinsp);

### Description: DbEnv::mutex_set_tas_spins

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 database environment's test-and-set spin count may also be configured 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.

The DbEnv::mutex_set_tas_spins method configures operations performed using the specified DbEnv handle, not all operations performed on the underlying database environment.

The DbEnv::mutex_set_tas_spins method may be called at any time during the life of the application.

The DbEnv::mutex_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.

### Parameters

tas_spins
  The tas_spins parameter is the number of spins test-and-set mutexes should execute before blocking.

### Errors

The DbEnv::mutex_set_tas_spins method may fail and throw DbException, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:

EINVAL
  An invalid flag value or parameter was specified.

### Description: DbEnv::mutex_get_tas_spins

The DbEnv::mutex_get_tas_spins method returns the test-and-set spin count.

The DbEnv::mutex_get_tas_spins method may be called at any time during the life of the application.

The DbEnv::mutex_get_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.

### Parameters

tas_spinsp
  The DbEnv::mutex_get_tas_spins method returns the test-and-set spin count in tas_spinsp.

### Class

DbEnv

### See Also

Database Environments and Related Methods`

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