com.sleepycat.je
Class EnvironmentMutableConfig

java.lang.Object
  com.sleepycat.je.EnvironmentMutableConfig

All Implemented Interfaces:

Serializable, Cloneable

Direct Known Subclasses:

EnvironmentConfig

public class EnvironmentMutableConfig
extends Object
implements Cloneable, Serializable

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);
 

The per-environment handle properties are listed below. These properties are accessed using the setter and getter methods listed, as shown in the example above.

• setDurability(com.sleepycat.je.Durability), getDurability()
• setTxnNoSync(boolean), getTxnNoSync() deprecated
• setTxnWriteNoSync(boolean), getTxnWriteNoSync() deprecated

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);
 

The environment-wide mutable properties are listed below. These properties are accessed using the setConfigParam(java.lang.String, java.lang.String) and getConfigParam(java.lang.String) methods, as shown in the example above, using the property names listed below. In some cases setter and getter methods are also available.

• je.maxMemory (setCacheSize(long), getCacheSize())
• je.maxMemoryPercent (setCachePercent(int), getCachePercent())
• je.env.runINCompressor
• je.env.runEvictor
• je.env.runCheckpointer
• je.env.runCleaner

Getting the Current Environment Properties

To get the current "live" properties of an environment after constructing it or changing its properties, you must call Environment.getConfig() or Environment.getMutableConfig(). The original EnvironmentConfig or EnvironmentMutableConfig object used to set the properties is not kept up to date as properties are changed, and does not reflect property validation or properties that are computed. @see EnvironmentConfig

See Also:

Serialized Form

Constructor Summary

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

Method Summary

CacheMode	getCacheMode() Returns the default CacheMode used for operations performed in this environment, or null if CacheMode.DEFAULT is used.
int	getCachePercent() Returns the percentage value used in the JE cache size calculation.
long	getCacheSize() Returns the memory available to the database system, in bytes.
String	getConfigParam(String paramName) Returns the value for this configuration parameter.
Durability	getDurability() Returns the durability associated with the configuration.
ExceptionListener	getExceptionListener() Returns the exception listener, if set.
boolean	getTxnNoSync() Deprecated. replaced by getDurability()
boolean	getTxnWriteNoSync() Deprecated. replaced by getDurability()
EnvironmentMutableConfig	setCacheMode(CacheMode cacheMode) Sets the default CacheMode used for operations performed in this environment.
EnvironmentMutableConfig	setCachePercent(int percent) By default, JE sets its cache size proportionally to the JVM memory.
EnvironmentMutableConfig	setCacheSize(long totalBytes) Configures the memory available to the database system, in bytes.
EnvironmentMutableConfig	setConfigParam(String paramName, String value) Set this configuration parameter.
EnvironmentMutableConfig	setDurability(Durability durability) Configures the durability associated with transactions.
EnvironmentMutableConfig	setExceptionListener(ExceptionListener exceptionListener) Sets the exception listener for an Environment.
EnvironmentMutableConfig	setTxnNoSync(boolean noSync) Deprecated. replaced by setDurability(com.sleepycat.je.Durability)
EnvironmentMutableConfig	setTxnWriteNoSync(boolean writeNoSync) Deprecated. replaced by setDurability(com.sleepycat.je.Durability)
String	toString() Display configuration values.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, 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 EnvironmentMutableConfig setTxnNoSync(boolean noSync)

Deprecated. replaced by setDurability(com.sleepycat.je.Durability)

Configures the database environment for asynchronous transactions.

Parameters:

noSync - 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 JVM or operating 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.

getTxnNoSync

public boolean getTxnNoSync()

Deprecated. replaced by getDurability()

Returns true if the database environment is configured for asynchronous transactions.

Returns:

true if the database environment is configured for asynchronous transactions.

setTxnWriteNoSync

public EnvironmentMutableConfig setTxnWriteNoSync(boolean writeNoSync)

Deprecated. replaced by setDurability(com.sleepycat.je.Durability)

Configures the database environment for transactions which write but do not flush the log.

Parameters:

writeNoSync - If true, write but do not 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 operating 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 often the operating system flushes dirty buffers to disk, and how often the database environment is checkpointed.

The motivation for this attribute is to provide a transaction that has more durability than asynchronous (nosync) transactions, but has higher performance than synchronous transactions.

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

getTxnWriteNoSync

public boolean getTxnWriteNoSync()

Deprecated. replaced by getDurability()

Returns true if the database environment is configured for transactions which write but do not flush the log.

Returns:

true if the database environment is configured for transactions which write but do not flush the log.

setDurability

public EnvironmentMutableConfig setDurability(Durability durability)

Configures the durability associated with transactions.

Equivalent to setting the je.txn.durability property in the je.properties file.

Parameters:

durability - the new durability definition

Returns:

this

See Also:

Durability

getDurability

public Durability getDurability()

Returns the durability associated with the configuration.

Returns:

the durability setting currently associated with this config.

setCacheSize

public EnvironmentMutableConfig setCacheSize(long totalBytes)
                                      throws IllegalArgumentException

Configures the memory available to the database system, in bytes.

Equivalent to setting the je.maxMemory property in the je.properties file. The system will evict database objects when it comes within a prescribed margin of the limit.

By default, JE sets the cache size to:

         je.maxMemoryPercent *  JVM maximum memory
 

where JVM maximum memory is specified by the JVM -Xmx flag. However, calling setCacheSize() with a non-zero value overrides the percentage based calculation and sets the cache size explicitly.

Note that the log buffer cache may be cleared if the cache size is changed after the environment has been opened.

If setSharedCache(true) is called, setCacheSize and setCachePercent specify the total size of the shared cache, and changing these parameters will change the size of the shared cache.

To take full advantage of JE cache memory, it is strongly recommended that compressed oops (-XX:+UseCompressedOops) is specified when a 64-bit JVM is used and the maximum heap size is less than 32 GB. As described in the referenced documentation, compressed oops is sometimes the default JVM mode even when it is not explicitly specified in the Java command. However, if compressed oops is desired then it must be explicitly specified in the Java command when running DbCacheSize or a JE application. If it is not explicitly specified then JE will not aware of it, even if it is the JVM default setting, and will not take it into account when calculating cache memory sizes.

Parameters:

totalBytes - The memory available to the database system, in bytes.

Returns:

this

Throws:

IllegalArgumentException - if an invalid parameter is specified.

getCacheSize

public long getCacheSize()

Returns the memory available to the database system, in bytes. A valid value is only available if this EnvironmentConfig object has been returned from Environment.getConfig();

Returns:

The memory available to the database system, in bytes.

setCachePercent

public EnvironmentMutableConfig setCachePercent(int percent)
                                         throws IllegalArgumentException

By default, JE sets its cache size proportionally to the JVM memory. This formula is used:

         je.maxMemoryPercent *  JVM maximum memory
 

where JVM maximum memory is specified by the JVM -Xmx flag. setCachePercent() specifies the percentage used and is equivalent to setting the je.maxMemoryPercent property in the je.properties file.

Calling setCacheSize() with a non-zero value overrides the percentage based calculation and sets the cache size explicitly.

Note that the log buffer cache may be cleared if the cache size is changed after the environment has been opened.

If setSharedCache(true) is called, setCacheSize and setCachePercent specify the total size of the shared cache, and changing these parameters will change the size of the shared cache.

To take full advantage of JE cache memory, it is strongly recommended that compressed oops (-XX:+UseCompressedOops) is specified when a 64-bit JVM is used and the maximum heap size is less than 32 GB. As described in the referenced documentation, compressed oops is sometimes the default JVM mode even when it is not explicitly specified in the Java command. However, if compressed oops is desired then it must be explicitly specified in the Java command when running DbCacheSize or a JE application. If it is not explicitly specified then JE will not aware of it, even if it is the JVM default setting, and will not take it into account when calculating cache memory sizes.

Parameters:

percent - The percent of JVM memory to allocate to the JE cache.

Returns:

this

Throws:

IllegalArgumentException - if an invalid parameter is specified.

getCachePercent

public int getCachePercent()

Returns the percentage value used in the JE cache size calculation.

Returns:

the percentage value used in the JE cache size calculation.

setExceptionListener

public EnvironmentMutableConfig setExceptionListener(ExceptionListener exceptionListener)

Sets the exception listener for an Environment. The listener is called when a daemon thread throws an exception, in order to provide a notification mechanism for these otherwise asynchronous exceptions. Daemon thread exceptions are also printed through stderr.

Not all daemon exceptions are fatal, and the application bears responsibility for choosing how to respond to the notification. Since exceptions may repeat, the application should also choose how to handle a spate of exceptions. For example, the application may choose to act upon each notification, or it may choose to batch up its responses by implementing the listener so it stores exceptions, and only acts when a certain number have been received.

Parameters:

exceptionListener - the callback to be executed when an exception occurs.

Returns:

this

getExceptionListener

public ExceptionListener getExceptionListener()

Returns the exception listener, if set.

setCacheMode

public EnvironmentMutableConfig setCacheMode(CacheMode cacheMode)

Sets the default CacheMode used for operations performed in this environment. The default cache mode may be overridden on a per-database basis using DatabaseConfig.setCacheMode(com.sleepycat.je.CacheMode), and on a per-record or per-operation basis using Cursor.setCacheMode(com.sleepycat.je.CacheMode).

Parameters:

cacheMode - is the default CacheMode used for operations performed in this environment. If null is specified, CacheMode.DEFAULT will be used.

Since:

4.0.97

See Also:

for further details.

getCacheMode

public CacheMode getCacheMode()

Returns the default CacheMode used for operations performed in this environment, or null if CacheMode.DEFAULT is used.

Returns:

the default CacheMode used for operations performed on this database, or null if CacheMode.DEFAULT is used.

Since:

4.0.97

See Also:

setCacheMode(com.sleepycat.je.CacheMode)

setConfigParam

public EnvironmentMutableConfig setConfigParam(String paramName,
                                               String value)
                                        throws IllegalArgumentException

Set this configuration parameter. First validate the value specified for the configuration parameter; if it is valid, the value is set in the configuration.

Parameters:

paramName - the configuration parameter name, one of the String constants in this class

value - The configuration value

Returns:

this

Throws:

IllegalArgumentException - if the paramName or value is invalid.

getConfigParam

public String getConfigParam(String paramName)
                      throws IllegalArgumentException

Returns the value for this configuration parameter.

Parameters:

paramName - a valid configuration parameter, one of the String constants in this class.

Returns:

the configuration value.

Throws:

IllegalArgumentException - if the paramName is invalid.

toString

public String toString()

Display configuration values.

Overrides:

toString in class Object