1 /**
2 * Logback: the reliable, generic, fast and flexible logging framework.
3 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
4 *
5 * This program and the accompanying materials are dual-licensed under
6 * either the terms of the Eclipse Public License v1.0 as published by
7 * the Eclipse Foundation
8 *
9 * or (per the licensee's choosing)
10 *
11 * under the terms of the GNU Lesser General Public License version 2.1
12 * as published by the Free Software Foundation.
13 */
14 package ch.qos.logback.core.spi;
15
16 import ch.qos.logback.core.CoreConstants;
17
18 import java.util.Collection;
19 import java.util.Set;
20
21 /**
22 * Interface for tracking various components by key. Components which have not
23 * been accessed for more than a user-specified duration are deemed stale and
24 * removed. Components can also be explicitly marked as having reached their
25 * {@link #endOfLife(String)} in which case they will linger for a few seconds
26 * and then be removed.
27 *
28 * @author Tommy Becker
29 * @author Ceki Gulcu
30 * @author David Roussel
31 *
32 * @since 1.0.12
33 */
34 public interface ComponentTracker<C> {
35
36 /**
37 * The default timeout duration is 30 minutes
38 */
39 public final int DEFAULT_TIMEOUT = (int) (30 * 60 * CoreConstants.MILLIS_IN_ONE_SECOND); // 30 minutes
40
41 /**
42 * By default an unlimited number of elements can be tracked.
43 */
44 int DEFAULT_MAX_COMPONENTS = Integer.MAX_VALUE;
45
46 /**
47 * Returns the number of components tracked.
48 *
49 * @return number of components
50 */
51 int getComponentCount();
52
53 /**
54 * Find the component identified by 'key', without updating the timestamp.
55 * Returns null if no corresponding component could be found.
56 *
57 * @param key
58 * @return corresponding component, may be null
59 */
60 C find(String key);
61
62 /**
63 * Get the component identified by 'key', updating its timestamp in the process.
64 * If the corresponding component could not be found, it is created.
65 *
66 * @param key
67 * @param timestamp
68 * @return
69 */
70 C getOrCreate(String key, long timestamp);
71
72 /**
73 * Remove components which are deemed stale. Components which have not been
74 * accessed for more than a user-specified duration are deemed stale.
75 *
76 * <p>
77 * If the number of components exceeds, {@link #getComponentCount()}, components
78 * in excess will be removed.
79 * </p>
80 *
81 * <p>
82 * Depending on the component type, components will be cleared or stopped (as
83 * appropriate) right before removal.
84 * </p>
85 *
86 * @param now current time in milliseconds
87 */
88 void removeStaleComponents(long now);
89
90 /**
91 * Mark component identified by 'key' as having reached its end-of-life.
92 * End-of-lifed components will linger for a few more seconds before being
93 * removed.
94 *
95 * @param key
96 */
97 void endOfLife(String key);
98
99 /**
100 * Returns the collection of all components tracked by this instance.
101 *
102 * @return collection of components
103 */
104 Collection<C> allComponents();
105
106 /**
107 * Set of all keys in this tracker in no particular order.
108 *
109 * @return
110 */
111 Set<String> allKeys();
112 }