org.apache.hadoop.hbase.coprocessor

Class BaseWALObserver

java.lang.Object

org.apache.hadoop.hbase.coprocessor.BaseWALObserver

All Implemented Interfaces:

Coprocessor, WALObserver

@InterfaceAudience.LimitedPrivate(value="Coprocesssor")
@InterfaceStability.Evolving
public class BaseWALObserver
extends Object
implements WALObserver

An abstract class that implements WALObserver. By extending it, you can create your own WAL observer without overriding all abstract methods of WALObserver.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.Coprocessor

Coprocessor.State

Field Summary

Fields inherited from interface org.apache.hadoop.hbase.Coprocessor

PRIORITY_HIGHEST, PRIORITY_LOWEST, PRIORITY_SYSTEM, PRIORITY_USER, VERSION

Constructor Summary

Constructors

Constructor and Description
BaseWALObserver()

Method Summary

Methods

Modifier and Type	Method and Description
void	postWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx, HRegionInfo info, WALKey logKey, WALEdit logEdit) Implementers should override this method and leave the deprecated version as-is.
void	postWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info, HLogKey logKey, WALEdit logEdit) Called after a WALEdit is writen to WAL.
boolean	preWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx, HRegionInfo info, WALKey logKey, WALEdit logEdit) Implementers should override this method and leave the deprecated version as-is.
boolean	preWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info, HLogKey logKey, WALEdit logEdit) Called before a WALEdit is writen to WAL.
void	start(CoprocessorEnvironment e)
void	stop(CoprocessorEnvironment e)

Methods inherited from class java.lang.Object

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

Constructor Detail

BaseWALObserver

public BaseWALObserver()

Method Detail

start

public void start(CoprocessorEnvironment e)
           throws IOException

Specified by:

start in interface Coprocessor

Throws:

IOException

stop

public void stop(CoprocessorEnvironment e)
          throws IOException

Specified by:

stop in interface Coprocessor

Throws:

IOException

preWALWrite

public boolean preWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
                  HRegionInfo info,
                  WALKey logKey,
                  WALEdit logEdit)
                    throws IOException

Implementers should override this method and leave the deprecated version as-is.

Specified by:

preWALWrite in interface WALObserver

Returns:

true if default behavior should be bypassed, false otherwise

Throws:

IOException

preWALWrite

public boolean preWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx,
                  HRegionInfo info,
                  HLogKey logKey,
                  WALEdit logEdit)
                    throws IOException

Description copied from interface: WALObserver

Called before a WALEdit is writen to WAL. This method is left in place to maintain binary compatibility with older WALObservers. If an implementation directly overrides WALObserver.preWALWrite(ObserverContext, HRegionInfo, WALKey, WALEdit) then this version won't be called at all, barring problems with the Security Manager. To work correctly in the presence of a strict Security Manager, or in the case of an implementation that relies on a parent class to implement preWALWrite, you should implement this method as a call to the non-deprecated version. Users of this method will see all edits that can be treated as HLogKey. If there are edits that can't be treated as HLogKey they won't be offered to coprocessors that rely on this method. If a coprocessor gets skipped because of this mechanism, a log message at ERROR will be generated per coprocessor on the logger for CoprocessorHost once per classloader.

Specified by:

preWALWrite in interface WALObserver

Returns:

true if default behavior should be bypassed, false otherwise

Throws:

IOException

postWALWrite

public void postWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
                HRegionInfo info,
                WALKey logKey,
                WALEdit logEdit)
                  throws IOException

Implementers should override this method and leave the deprecated version as-is.

Specified by:

postWALWrite in interface WALObserver

Throws:

IOException

postWALWrite

public void postWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx,
                HRegionInfo info,
                HLogKey logKey,
                WALEdit logEdit)
                  throws IOException

Description copied from interface: WALObserver

Called after a WALEdit is writen to WAL. This method is left in place to maintain binary compatibility with older WALObservers. If an implementation directly overrides WALObserver.postWALWrite(ObserverContext, HRegionInfo, WALKey, WALEdit) then this version won't be called at all, barring problems with the Security Manager. To work correctly in the presence of a strict Security Manager, or in the case of an implementation that relies on a parent class to implement preWALWrite, you should implement this method as a call to the non-deprecated version. Users of this method will see all edits that can be treated as HLogKey. If there are edits that can't be treated as HLogKey they won't be offered to coprocessors that rely on this method. If a coprocessor gets skipped because of this mechanism, a log message at ERROR will be generated per coprocessor on the logger for CoprocessorHost once per classloader.

Specified by:

postWALWrite in interface WALObserver

Throws:

IOException