org.dbmaintain.structure.clear.impl
Class MultiPassErrorHandler

java.lang.Object
  org.dbmaintain.structure.clear.impl.MultiPassErrorHandler

public class MultiPassErrorHandler
extends Object

This class is intended to permit multiple attempts (passes) to drop database objects. It helps to solve the problem whereby it is impossible to drop one database object because a dependent object exists (for example when dropping Oracle 11 reference partitioned objects it is necessary to drop all child tables first).

This class is used in a do-while loop with the method continueExecutionAfterPass() being the loop continuation condition.

 do{
 dropObjects(database);
 }
 while ( multiPassErrorHandler.continueExecutionAfterPass() );
 

In addition whenever an exception occurs it must be recorded with the addError(RuntimeException) method.

 try {
 dropObject(objectName);
 } catch (RuntimeException e) {
 multiPassErrorHandler.addError(e);
 }
 

Author:

Mark Jeffrey

Constructor Summary

MultiPassErrorHandler()

Method Summary

void	addError(RuntimeException exception) Call this method whenever there is an exception dropping a database object.
boolean	continueExecutionAfterPass() We stop execution if: We have no exceptions during the most recent pass.

Methods inherited from class java.lang.Object

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

Constructor Detail

MultiPassErrorHandler

public MultiPassErrorHandler()

Method Detail

addError

public void addError(RuntimeException exception)

Call this method whenever there is an exception dropping a database object. This method keeps track of:

1. the first exception (so that it may be reported later).
2. the exception count so we can determine if they are still decreasing.

If an Exception occurs during a pass then we need to do two things:

Parameters:

exception -

continueExecutionAfterPass

public boolean continueExecutionAfterPass()

We stop execution if:

• We have no exceptions during the most recent pass.

We continue execution if:

• We had exceptions and it was the first pass.
• We are after the first pass and the number of exceptions is non-zero but decreasing.

We throw the first exception of the pass if:

• After the first pass we did not have a decreasing number of exceptions.

Returns:

true if we should continue execution (trying another pass), false if no exceptions occurred in the most recent pass.

Throws:

RuntimeException - If we do not get a decreasing number of exceptions each pass then we throw the first exception from the most recent pass.