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1 | /******************************************************************************* |
2 | * Copyright (c) 2013 Ericsson | |
3 | * | |
4 | * All rights reserved. This program and the accompanying materials are | |
5 | * made available under the terms of the Eclipse Public License v1.0 which | |
6 | * accompanies this distribution, and is available at | |
7 | * http://www.eclipse.org/legal/epl-v10.html | |
8 | * | |
9 | * Contributors: | |
10 | * Alexandre Montplaisir - Initial API and implementation | |
11 | *******************************************************************************/ | |
12 | ||
13 | package org.eclipse.linuxtools.internal.tmf.core.statesystem.backends; | |
14 | ||
15 | import java.io.File; | |
16 | import java.io.FileInputStream; | |
17 | import java.io.PrintWriter; | |
18 | import java.util.List; | |
19 | ||
f9a76cac AM |
20 | import org.eclipse.linuxtools.tmf.core.interval.ITmfStateInterval; |
21 | import org.eclipse.linuxtools.tmf.core.statevalue.ITmfStateValue; | |
22 | ||
23 | /** | |
24 | * An implement of a state history back-end to simply discards *all* the | |
25 | * intervals it receives. Obviously, no queries can be done on it. It is useful | |
cb42195c AM |
26 | * for using with a StateSystem on which you will only want to do "ongoing" |
27 | * requests. | |
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28 | * |
29 | * @author Alexandre Montplaisir | |
30 | */ | |
31 | public class NullBackend implements IStateHistoryBackend { | |
32 | ||
33 | /** | |
34 | * Constructor | |
35 | */ | |
36 | public NullBackend() {} | |
37 | ||
38 | @Override | |
39 | public long getStartTime() { | |
40 | return 0; | |
41 | } | |
42 | ||
43 | @Override | |
44 | public long getEndTime() { | |
45 | return 0; | |
46 | } | |
47 | ||
48 | /** | |
49 | * The interval will be discarded when using a null backend. | |
50 | */ | |
51 | @Override | |
52 | public void insertPastState(long stateStartTime, long stateEndTime, | |
53 | int quark, ITmfStateValue value) { | |
54 | /* The interval is always discarded. */ | |
55 | } | |
56 | ||
57 | @Override | |
58 | public void finishedBuilding(long endTime) { | |
59 | /* Nothing to do */ | |
60 | } | |
61 | ||
62 | @Override | |
63 | public FileInputStream supplyAttributeTreeReader() { | |
64 | return null; | |
65 | } | |
66 | ||
67 | @Override | |
68 | public File supplyAttributeTreeWriterFile() { | |
69 | return null; | |
70 | } | |
71 | ||
72 | @Override | |
73 | public long supplyAttributeTreeWriterFilePosition() { | |
74 | return -1; | |
75 | } | |
76 | ||
77 | @Override | |
78 | public void removeFiles() { | |
79 | /* Nothing to do */ | |
80 | } | |
81 | ||
82 | @Override | |
83 | public void dispose() { | |
84 | /* Nothing to do */ | |
85 | } | |
86 | ||
87 | /** | |
88 | * Null back-ends cannot run queries. Nothing will be put in | |
89 | * currentStateInfo. | |
90 | */ | |
91 | @Override | |
92 | public void doQuery(List<ITmfStateInterval> currentStateInfo, long t) { | |
93 | /* Cannot do past queries */ | |
94 | } | |
95 | ||
96 | /** | |
97 | * Null back-ends cannot run queries. 'null' will be returned. | |
98 | * | |
99 | * @return Always returns null. | |
100 | */ | |
101 | @Override | |
102 | public ITmfStateInterval doSingularQuery(long t, int attributeQuark) { | |
103 | /* Cannot do past queries */ | |
104 | return null; | |
105 | } | |
106 | ||
107 | /** | |
108 | * Null back-ends cannot run queries. | |
109 | * | |
110 | * @return Always returns false. | |
111 | */ | |
112 | @Override | |
113 | public boolean checkValidTime(long t) { | |
114 | /* Cannot do past queries */ | |
115 | return false; | |
116 | } | |
117 | ||
118 | @Override | |
119 | public void debugPrint(PrintWriter writer) { | |
120 | writer.println("Null history backend"); //$NON-NLS-1$ | |
121 | } | |
122 | } |