|
|||||||||||||||||||
Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
FIFOCache.java | 75% | 77,8% | 83,3% | 78,6% |
|
1 |
/*
|
|
2 |
* Copyright (c) 2002-2003 by OpenSymphony
|
|
3 |
* All rights reserved.
|
|
4 |
*/
|
|
5 |
package com.opensymphony.oscache.base.algorithm;
|
|
6 |
|
|
7 |
import java.util.*;
|
|
8 |
|
|
9 |
/**
|
|
10 |
* FIFO (First In First Out) based queue algorithm for the cache.
|
|
11 |
*
|
|
12 |
* No synchronization is required in this class since the
|
|
13 |
* <code>AbstractConcurrentReadCache</code> already takes care of any
|
|
14 |
* synchronization requirements.
|
|
15 |
*
|
|
16 |
* @version $Revision: 1.1 $
|
|
17 |
* @author <a href="mailto:mike@atlassian.com">Mike Cannon-Brookes</a>
|
|
18 |
* @author <a href="mailto:abergevin@pyxis-tech.com">Alain Bergevin</a>
|
|
19 |
* @author <a href="mailto:chris@swebtec.com">Chris Miller</a>
|
|
20 |
*/
|
|
21 |
public class FIFOCache extends AbstractConcurrentReadCache { |
|
22 |
/**
|
|
23 |
* A queue containing all cache keys
|
|
24 |
*/
|
|
25 |
private Collection list;
|
|
26 |
|
|
27 |
/**
|
|
28 |
* A flag indicating whether we are using a List or a Set for the key collection
|
|
29 |
*/
|
|
30 |
private boolean isSet = false; |
|
31 |
|
|
32 |
/**
|
|
33 |
* Constructs a FIFO Cache.
|
|
34 |
*/
|
|
35 | 6 |
public FIFOCache() {
|
36 | 6 |
super();
|
37 |
|
|
38 |
// Check if we're running under JRE 1.4+. If so we can use a LinkedHashSet
|
|
39 |
// instead of a LinkedList for a big performance boost when removing elements.
|
|
40 | 6 |
try {
|
41 | 6 |
Class.forName("java.util.LinkedHashSet");
|
42 | 6 |
list = new LinkedHashSet();
|
43 | 6 |
isSet = true;
|
44 |
} catch (ClassNotFoundException e) {
|
|
45 | 0 |
list = new LinkedList();
|
46 |
} |
|
47 |
} |
|
48 |
|
|
49 |
/**
|
|
50 |
* Constructs a FIFO Cache of the specified capacity.
|
|
51 |
*
|
|
52 |
* @param capacity The maximum cache capacity.
|
|
53 |
*/
|
|
54 | 0 |
public FIFOCache(int capacity) { |
55 | 0 |
this();
|
56 | 0 |
maxEntries = capacity; |
57 |
} |
|
58 |
|
|
59 |
/**
|
|
60 |
* An object was retrieved from the cache. This implementation
|
|
61 |
* does noting since this event has no impact on the FIFO algorithm.
|
|
62 |
*
|
|
63 |
* @param key The cache key of the item that was retrieved.
|
|
64 |
*/
|
|
65 | 12 |
protected void itemRetrieved(Object key) { |
66 |
} |
|
67 |
|
|
68 |
/**
|
|
69 |
* An object was put in the cache. This implementation just adds
|
|
70 |
* the key to the end of the list if it doesn't exist in the list
|
|
71 |
* already.
|
|
72 |
*
|
|
73 |
* @param key The cache key of the item that was put.
|
|
74 |
*/
|
|
75 | 66 |
protected void itemPut(Object key) { |
76 | 66 |
if (!list.contains(key)) {
|
77 | 60 |
list.add(key); |
78 |
} |
|
79 |
} |
|
80 |
|
|
81 |
/**
|
|
82 |
* An item needs to be removed from the cache. The FIFO implementation
|
|
83 |
* removes the first element in the list (ie, the item that has been in
|
|
84 |
* the cache for the longest time).
|
|
85 |
*
|
|
86 |
* @return The key of whichever item was removed.
|
|
87 |
*/
|
|
88 | 15 |
protected Object removeItem() {
|
89 | 15 |
Object toRemove; |
90 |
|
|
91 | 15 |
if (isSet) {
|
92 | 15 |
Iterator it = list.iterator(); |
93 | 15 |
toRemove = it.next(); |
94 | 15 |
it.remove(); |
95 |
} else {
|
|
96 | 0 |
toRemove = ((List) list).remove(0); |
97 |
} |
|
98 |
|
|
99 | 15 |
return toRemove;
|
100 |
} |
|
101 |
|
|
102 |
/**
|
|
103 |
* Remove specified key since that object has been removed from the cache.
|
|
104 |
*
|
|
105 |
* @param key The cache key of the item that was removed.
|
|
106 |
*/
|
|
107 | 45 |
protected void itemRemoved(Object key) { |
108 | 45 |
list.remove(key); |
109 |
} |
|
110 |
} |
|
111 |
|
|