org.apache.derby.impl.store.raw.xact
Class TransactionTable.UpdateTransactionCounter

java.lang.Object
  org.apache.derby.impl.store.raw.xact.TransactionTable.UpdateTransactionCounter

All Implemented Interfaces:

TransactionTable.EntryVisitor

Enclosing class:

TransactionTable

private static class TransactionTable.UpdateTransactionCounter
extends java.lang.Object
implements TransactionTable.EntryVisitor

Visitor class that counts update transactions. Note that update transactions may be added or removed concurrently unless the caller synchronizes on "this" (the TransactionTable instance) while applying the visitor.

Field Summary

private int	count
private boolean	stopOnFirst

Constructor Summary

TransactionTable.UpdateTransactionCounter(boolean stopOnFirst)
Create an instance of this visitor.

Method Summary

(package private) int	getCount() Get the number of update transactions seen by this visitor
boolean	visit(TransactionTableEntry entry) Check if the entry represents an update transaction, and update the counter accordingly.

Methods inherited from class java.lang.Object

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

Field Detail

stopOnFirst

private final boolean stopOnFirst

count

private int count

Constructor Detail

TransactionTable.UpdateTransactionCounter

TransactionTable.UpdateTransactionCounter(boolean stopOnFirst)

Create an instance of this visitor.

Parameters:

stopOnFirst - if true, stop the scan as soon as we have found one update transaction (useful if all we care about is whether or not the transaction table contains an update transaction); otherwise, scan the entire transaction table

Method Detail

visit

public boolean visit(TransactionTableEntry entry)

Check if the entry represents an update transaction, and update the counter accordingly.

Specified by:

visit in interface TransactionTable.EntryVisitor

Parameters:

entry - the TransactionTableEntry being visited

Returns:

true if the scan of the transaction table should continue, or false if the visitor has completed its work and no more entries need to be visited

getCount

int getCount()

Get the number of update transactions seen by this visitor

Returns:

number of update transactions