Class JDBCStatementCache.BoundedLinkedHashMap

java.lang.Object

java.util.AbstractMap<StatementKey, PreparedStatement>

java.util.HashMap<StatementKey, PreparedStatement>

java.util.LinkedHashMap<StatementKey, PreparedStatement>

org.apache.derby.client.am.stmtcache.JDBCStatementCache.BoundedLinkedHashMap

All Implemented Interfaces:

Serializable, Cloneable, Map<StatementKey, PreparedStatement>, SequencedMap<StatementKey, PreparedStatement>

Enclosing class:

JDBCStatementCache

private static class JDBCStatementCache.BoundedLinkedHashMap
extends LinkedHashMap<StatementKey, PreparedStatement>

A LinkedHashMap with an upper bound on the number of entries.

If the maximum size is exceeded, the oldest entry is automatically removed after the new entry has been inserted.

Nested Class Summary

Nested classes/interfaces inherited from class AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Field Summary

Fields

Modifier and Type	Field	Description
private final int	maxSize	Maximum number of entries.

Constructor Summary

Constructors

Constructor	Description
BoundedLinkedHashMap(int maxCapacity)	Creates a bounded LinkedHashMap with the specified maximum size.

Method Summary

Modifier and Type	Method	Description
protected boolean	removeEldestEntry(Map.Entry<StatementKey, PreparedStatement> eldest)	Tells if an entry should be removed from the map.

Methods inherited from class LinkedHashMap

clear, containsValue, entrySet, forEach, get, getOrDefault, keySet, newLinkedHashMap, putFirst, putLast, replaceAll, reversed, sequencedEntrySet, sequencedKeySet, sequencedValues, values

Methods inherited from class HashMap

clone, compute, computeIfAbsent, computeIfPresent, containsKey, isEmpty, merge, newHashMap, put, putAll, putIfAbsent, remove, remove, replace, replace, size

Methods inherited from class AbstractMap

equals, hashCode, toString

Methods inherited from class Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface Map

compute, computeIfAbsent, computeIfPresent, containsKey, equals, hashCode, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, size

Methods inherited from interface SequencedMap

firstEntry, lastEntry, pollFirstEntry, pollLastEntry

Field Details

maxSize

private final int maxSize

Maximum number of entries.

Constructor Details

BoundedLinkedHashMap

public BoundedLinkedHashMap(int maxCapacity)

Creates a bounded LinkedHashMap with the specified maximum size.

Iteration is by insertion-order.

Parameters:

maxCapacity - maximum size of the map

Method Details

removeEldestEntry

protected boolean removeEldestEntry(Map.Entry<StatementKey, PreparedStatement> eldest)

Tells if an entry should be removed from the map.

If the cache has exceeded its maximum size, the oldest element will be marked for removal. The oldest element will be removed after the new element has been inserted.

Overrides:

removeEldestEntry in class LinkedHashMap<StatementKey, PreparedStatement>

Parameters:

eldest - the element picked out for removal

Returns:

true if the element is to be removed, false if not.