com.sleepycat.je
Class EnvironmentMutableConfig

java.lang.Object
  |
  +--com.sleepycat.je.EnvironmentMutableConfig

All Implemented Interfaces:

Cloneable

Direct Known Subclasses:

EnvironmentConfig

public class EnvironmentMutableConfig

extends Object

implements Cloneable

Specifies the environment attributes that may be changed after the environment has been opened. EnvironmentMutableConfig is a parameter to Environment.setMutableConfig(com.sleepycat.je.EnvironmentMutableConfig) and is returned by Environment.getMutableConfig().

There are two types of mutable environment properties: per-environment handle properties, and environment wide properties.

Per-Environment Handle Properties

Per-environment handle properties apply only to a single Environment instance. For example, to change the default transaction commit behavior for a single environment handle, do this:

// Specify no-sync behavior for a given handle.
EnvironmentMutableConfig mutableConfig = myEnvHandle.getMutableConfig();
mutableConfig.setTxnNoSync(true);
myEnvHandle.setMutableConfig(mutableConfig);

Currently the only per-environment handle property is TxnNoSync, which may be changed as described above.

Environment-Wide Mutable Properties

Environment-wide mutable properties are those that can be changed for an environment as a whole, irrespective of which environment instance (for the same physical environment) is used. For example, to stop the cleaner daemon thread, do this:

// Stop the cleaner daemon thread for the environment.
EnvironmentMutableConfig mutableConfig = myEnvHandle.getMutableConfig();
mutableConfig.setConfigParam("je.env.runCleaner", "false");
myEnvHandle.setMutableConfig(mutableConfig);

Currently the environment-wide mutable properties are:

• je.env.runINCompressor
• je.env.runEvictor
• je.env.runCheckpointer
• je.env.runCleaner

Constructor Summary

EnvironmentMutableConfig()
An instance created using the default constructor is initialized with the system's default settings.

Method Summary

String	getConfigParam(String configParamName) Return the value for this configuration parameter.
boolean	getTxnNoSync() Return if the database environment is configured for asynchronous transactions.
void	setConfigParam(String configParamName, String value) Validate the value prescribed for the configuration parameter; if it is valid, the value is set in the configuration.
void	setTxnNoSync(boolean txnNoSync) Configure the database environment for asynchronous transactions.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

EnvironmentMutableConfig

public EnvironmentMutableConfig()

An instance created using the default constructor is initialized with the system's default settings.

Method Detail

setTxnNoSync

public void setTxnNoSync(boolean txnNoSync)

Configure the database environment for asynchronous transactions.

Parameters:

txnNoSync - If true, do not write or synchronously flush the log on transaction commit. This means that transactions exhibit the ACI (Atomicity, Consistency, and Isolation) properties, but not D (Durability); that is, database integrity is maintained, but if the application or system fails, it is possible some number of the most recently committed transactions may be undone during recovery. The number of transactions at risk is governed by how many updates fit into a log buffer, how often the operating system flushes dirty buffers to disk, and how often the database environment is checkpointed.

This attribute is false by default for this class and for the database environment.

Throws:

DatabaseException - if a failure occurs.

getTxnNoSync

public boolean getTxnNoSync()

Return if the database environment is configured for asynchronous transactions.

Returns:

If the database environment is configured for asynchronous transactions.

setConfigParam

public void setConfigParam(String configParamName,
                           String value)
                    throws IllegalArgumentException

Validate the value prescribed for the configuration parameter; if it is valid, the value is set in the configuration.

Parameters:

configParamName - The name of the configuration parameter. See the sample je.properties file for descriptions of all parameters.

value - The value for this configuration parameter.

Throws:

IllegalArgumentException - if an invalid parameter was specified.

DatabaseException - if a failure occurs.

getConfigParam

public String getConfigParam(String configParamName)
                      throws IllegalArgumentException

Return the value for this configuration parameter.

Parameters:

configParamName - Name of the requested parameter.

Throws:

IllegalArgumentException - if the configParamName is invalid.