Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
EvictionTimer |
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1 | /* | |
2 | * Licensed to the Apache Software Foundation (ASF) under one or more | |
3 | * contributor license agreements. See the NOTICE file distributed with | |
4 | * this work for additional information regarding copyright ownership. | |
5 | * The ASF licenses this file to You under the Apache License, Version 2.0 | |
6 | * (the "License"); you may not use this file except in compliance with | |
7 | * the License. You may obtain a copy of the License at | |
8 | * | |
9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
10 | * | |
11 | * Unless required by applicable law or agreed to in writing, software | |
12 | * distributed under the License is distributed on an "AS IS" BASIS, | |
13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
14 | * See the License for the specific language governing permissions and | |
15 | * limitations under the License. | |
16 | */ | |
17 | ||
18 | package org.apache.commons.pool.impl; | |
19 | ||
20 | import java.util.Timer; | |
21 | import java.util.TimerTask; | |
22 | ||
23 | /** | |
24 | * <p> | |
25 | * Provides a shared idle object eviction timer for all pools. This class wraps | |
26 | * the standard {@link Timer} and keeps track of how many pools are using it. | |
27 | * If no pools are using the timer, it is canceled. This prevents a thread | |
28 | * being left running which, in application server environments, can lead to | |
29 | * memory leads and/or prevent applications from shutting down or reloading | |
30 | * cleanly. | |
31 | * </p> | |
32 | * <p> | |
33 | * This class has package scope to prevent its inclusion in the pool public API. | |
34 | * The class declaration below should *not* be changed to public. | |
35 | * </p> | |
36 | */ | |
37 | class EvictionTimer { | |
38 | ||
39 | /** Timer instance */ | |
40 | private static Timer _timer; | |
41 | ||
42 | /** Static usage count tracker */ | |
43 | private static int _usageCount; | |
44 | ||
45 | /** Prevent instantiation */ | |
46 | 0 | private EvictionTimer() { |
47 | // Hide the default constuctor | |
48 | 0 | } |
49 | ||
50 | /** | |
51 | * Add the specified eviction task to the timer. Tasks that are added with a | |
52 | * call to this method *must* call {@link #cancel(TimerTask)} to cancel the | |
53 | * task to prevent memory and/or thread leaks in application server | |
54 | * environments. | |
55 | * @param task Task to be scheduled | |
56 | * @param delay Delay in milliseconds before task is executed | |
57 | * @param period Time in milliseconds between executions | |
58 | */ | |
59 | static synchronized void schedule(TimerTask task, long delay, long period) { | |
60 | 0 | if (null == _timer) { |
61 | 0 | _timer = new Timer(true); |
62 | } | |
63 | 0 | _usageCount++; |
64 | 0 | _timer.schedule(task, delay, period); |
65 | 0 | } |
66 | ||
67 | /** | |
68 | * Remove the specified eviction task from the timer. | |
69 | * @param task Task to be scheduled | |
70 | */ | |
71 | static synchronized void cancel(TimerTask task) { | |
72 | 0 | task.cancel(); |
73 | 0 | _usageCount--; |
74 | 0 | if (_usageCount == 0) { |
75 | 0 | _timer.cancel(); |
76 | 0 | _timer = null; |
77 | } | |
78 | 0 | } |
79 | } |