Commit | Line | Data |
---|---|---|
8c8bf09f | 1 | /******************************************************************************* |
4ab33d2b | 2 | * Copyright (c) 2009 Ericsson |
8c8bf09f ASL |
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: | |
1f506a43 | 10 | * Francois Chouinard - Initial API and implementation |
8c8bf09f ASL |
11 | *******************************************************************************/ |
12 | ||
13 | package org.eclipse.linuxtools.tmf.event; | |
14 | ||
8c8bf09f ASL |
15 | /** |
16 | * <b><u>TmfTimestamp</u></b> | |
17 | * <p> | |
18 | * The fundamental time reference in the TMF. | |
19 | * <p> | |
20 | * It provides a generic timestamp implementation in its most basic form: | |
21 | * <ul> | |
1f506a43 FC |
22 | * <li>an unstructured integer value |
23 | * <li>a time scale corresponding to the magnitude of the value wrt some | |
24 | * application-specific base unit (e.g. the second) | |
25 | * <li>a precision to indicate the error on the value (useful for comparing | |
26 | * timestamps in different scales). Default: 0. | |
8c8bf09f | 27 | * </ul> |
1f506a43 FC |
28 | * To allow synchronization of timestamps from different reference clocks, there |
29 | * is a possibility to "adjust" the timestamp both by changing its scale (traces | |
30 | * of different scale) and by adding an offset to its value (clock drift between | |
31 | * traces). | |
8c8bf09f | 32 | * <p> |
1f506a43 FC |
33 | * Note that the adjusted timestamp value could be negative e.g. for events that |
34 | * occurred before t0 of the reference clock. | |
35 | * | |
8c8bf09f | 36 | */ |
4ab33d2b | 37 | public class TmfTimestamp { |
8c8bf09f | 38 | |
4ab33d2b | 39 | // ======================================================================== |
8c8bf09f | 40 | // Attributes |
4ab33d2b | 41 | // ======================================================================== |
8c8bf09f | 42 | |
1f506a43 FC |
43 | protected final long fValue; // The timestamp value |
44 | protected final byte fScale; // The time scale | |
45 | protected final long fPrecision; // The value precision (tolerance) | |
8c8bf09f | 46 | |
4ab33d2b | 47 | // ======================================================================== |
8c8bf09f | 48 | // Constants |
4ab33d2b | 49 | // ======================================================================== |
8c8bf09f ASL |
50 | |
51 | // The beginning and end of time | |
146a887c | 52 | public static final TmfTimestamp BigBang = new TmfTimestamp(Long.MIN_VALUE, Byte.MAX_VALUE, 0); |
8c8bf09f | 53 | public static final TmfTimestamp BigCrunch = new TmfTimestamp(Long.MAX_VALUE, Byte.MAX_VALUE, 0); |
8c8bf09f | 54 | |
4ab33d2b | 55 | // ======================================================================== |
8c8bf09f | 56 | // Constructors |
4ab33d2b | 57 | // ======================================================================== |
8c8bf09f ASL |
58 | |
59 | /** | |
1f506a43 | 60 | * Default constructor. |
8c8bf09f ASL |
61 | */ |
62 | public TmfTimestamp() { | |
63 | this(0, (byte) 0, 0); | |
64 | } | |
65 | ||
1f506a43 FC |
66 | /** |
67 | * Simple constructor. | |
68 | */ | |
69 | public TmfTimestamp(long value) { | |
70 | this(value, (byte) 0, 0); | |
71 | } | |
72 | ||
8c8bf09f | 73 | /** |
4ab33d2b | 74 | * Simple constructor with default error value |
8c8bf09f | 75 | * |
1f506a43 FC |
76 | * @param value |
77 | * @param scale | |
8c8bf09f ASL |
78 | */ |
79 | public TmfTimestamp(long value, byte scale) { | |
80 | this(value, scale, 0); | |
81 | } | |
82 | ||
83 | /** | |
4ab33d2b | 84 | * Constructor with measurement error. |
8c8bf09f | 85 | * |
1f506a43 FC |
86 | * @param value |
87 | * @param scale | |
88 | * @param precision | |
8c8bf09f ASL |
89 | */ |
90 | public TmfTimestamp(long value, byte scale, long precision) { | |
91 | fValue = value; | |
92 | fScale = scale; | |
93 | fPrecision = Math.abs(precision); | |
94 | } | |
95 | ||
96 | /** | |
4ab33d2b | 97 | * Copy constructor. |
8c8bf09f | 98 | * |
1f506a43 | 99 | * @param other |
8c8bf09f ASL |
100 | */ |
101 | public TmfTimestamp(TmfTimestamp other) { | |
4ab33d2b | 102 | this(other.fValue, other.fScale, other.fPrecision); |
8c8bf09f ASL |
103 | } |
104 | ||
4ab33d2b | 105 | // ======================================================================== |
8c8bf09f | 106 | // Accessors |
4ab33d2b | 107 | // ======================================================================== |
8c8bf09f ASL |
108 | |
109 | /** | |
4ab33d2b | 110 | * @return The timestamp value |
8c8bf09f ASL |
111 | */ |
112 | public long getValue() { | |
113 | return fValue; | |
114 | } | |
115 | ||
116 | /** | |
4ab33d2b | 117 | * @return The timestamp scale |
8c8bf09f ASL |
118 | */ |
119 | public byte getScale() { | |
120 | return fScale; | |
121 | } | |
122 | ||
123 | /** | |
4ab33d2b | 124 | * @return The timestamp value precision |
8c8bf09f ASL |
125 | */ |
126 | public long getPrecision() { | |
127 | return fPrecision; | |
128 | } | |
129 | ||
4ab33d2b | 130 | // ======================================================================== |
8c8bf09f | 131 | // Operators |
4ab33d2b AO |
132 | // ======================================================================== |
133 | ||
8c8bf09f ASL |
134 | /** |
135 | * Return a shifted and scaled timestamp. | |
136 | * | |
137 | * Limitation: The scaling is limited to MAX_SCALING orders of magnitude. | |
138 | * The main reason is that the 64 bits value starts to lose any significance | |
139 | * meaning beyond that scale difference and it's not even worth the trouble | |
140 | * to switch to BigDecimal arithmetics. | |
141 | * | |
1f506a43 FC |
142 | * @param offset |
143 | * - the shift value (in the same scale as newScale) | |
144 | * @param newScale | |
145 | * - the new scale | |
146 | * @return The synchronized timestamp | |
8c8bf09f | 147 | */ |
8c8bf09f | 148 | |
4ab33d2b AO |
149 | /* |
150 | * A java <code>long</code> has a maximum of 19 significant digits. | |
151 | * (-9,223,372,036,854,775,808 .. +9,223,372,036,854,775,807) | |
152 | * | |
153 | * It is therefore useless to try to synchronize 2 timestamps whose | |
154 | * difference in scale exceeds that value. | |
155 | */ | |
156 | private static int MAX_SCALING = 19; | |
1f506a43 | 157 | |
4ab33d2b AO |
158 | public TmfTimestamp synchronize(long offset, byte newScale) throws ArithmeticException { |
159 | long newValue = fValue; | |
8c8bf09f ASL |
160 | long newPrecision = fPrecision; |
161 | ||
162 | // Determine the scaling factor | |
163 | if (fScale != newScale) { | |
164 | int scaleDiff = Math.abs(fScale - newScale); | |
165 | // Let's try to be realistic... | |
166 | if (scaleDiff > MAX_SCALING) { | |
167 | throw new ArithmeticException("Scaling exception"); | |
168 | } | |
1f506a43 | 169 | // Not pretty... |
8c8bf09f | 170 | long scalingFactor = 1; |
1f506a43 | 171 | for (int i = 0; i < scaleDiff; i++) { |
8c8bf09f ASL |
172 | scalingFactor *= 10; |
173 | } | |
174 | if (newScale < fScale) { | |
175 | newValue *= scalingFactor; | |
176 | newPrecision *= scalingFactor; | |
177 | } else { | |
178 | newValue /= scalingFactor; | |
179 | newPrecision /= scalingFactor; | |
180 | } | |
181 | } | |
182 | ||
183 | return new TmfTimestamp(newValue + offset, newScale, newPrecision); | |
184 | } | |
185 | ||
186 | /** | |
187 | * Compute the adjustment, in the reference scale, needed to synchronize | |
1f506a43 | 188 | * this timestamp with a reference timestamp. |
8c8bf09f | 189 | * |
1f506a43 FC |
190 | * @param reference |
191 | * - the reference timestamp to synchronize with | |
4ab33d2b AO |
192 | * @return The adjustment term in the reference time scale |
193 | * @throws TmfNumericalException | |
8c8bf09f | 194 | */ |
4ab33d2b AO |
195 | public long getAdjustment(TmfTimestamp reference) throws ArithmeticException { |
196 | TmfTimestamp ts = synchronize(0, reference.fScale); | |
197 | return reference.fValue - ts.fValue; | |
8c8bf09f ASL |
198 | } |
199 | ||
200 | /** | |
201 | * Compare with another timestamp | |
202 | * | |
1f506a43 FC |
203 | * @param other |
204 | * - the other timestamp | |
205 | * @param withinPrecision | |
206 | * - indicates if precision is to be take into consideration | |
207 | * @return <li>-1: this timestamp is lower <li>0: timestamps are equal | |
208 | * (within precision if requested) <li>1: this timestamp is higher | |
4ab33d2b | 209 | * @throws TmfNumericalException |
8c8bf09f ASL |
210 | */ |
211 | public int compareTo(final TmfTimestamp other, boolean withinPrecision) { | |
212 | ||
62d1696a | 213 | // If values have the same time scale, perform the comparison |
8c8bf09f ASL |
214 | if (fScale == other.fScale) { |
215 | if (withinPrecision) { | |
216 | if ((fValue + fPrecision) < (other.fValue - other.fPrecision)) | |
217 | return -1; | |
218 | if ((fValue - fPrecision) > (other.fValue + other.fPrecision)) | |
219 | return 1; | |
220 | return 0; | |
221 | } | |
1f506a43 FC |
222 | return (fValue == other.fValue) ? 0 : (fValue < other.fValue) ? -1 |
223 | : 1; | |
8c8bf09f ASL |
224 | } |
225 | ||
226 | // If values have different time scales, adjust to the finest one and | |
227 | // then compare. If the scaling difference is too large, revert to | |
228 | // some heuristics. Hopefully, nobody will try to compare galactic and | |
62d1696a | 229 | // quantic clock events... |
8c8bf09f ASL |
230 | byte newScale = (fScale < other.fScale) ? fScale : other.fScale; |
231 | try { | |
232 | TmfTimestamp ts1 = this.synchronize(0, newScale); | |
233 | TmfTimestamp ts2 = other.synchronize(0, newScale); | |
234 | return ts1.compareTo(ts2, withinPrecision); | |
235 | } catch (ArithmeticException e) { | |
4ab33d2b | 236 | if ((fValue == 0) || (other.fValue == 0)) { |
1f506a43 FC |
237 | return (fValue == other.fValue) ? 0 |
238 | : (fValue < other.fValue) ? -1 : 1; | |
4ab33d2b AO |
239 | } |
240 | if ((fValue > 0) && (other.fValue > 0)) { | |
241 | return (fScale < other.fScale) ? -1 : 1; | |
242 | } | |
243 | if ((fValue < 0) && (other.fValue < 0)) { | |
244 | return (fScale > other.fScale) ? -1 : 1; | |
245 | } | |
246 | return (fValue < 0) ? -1 : 1; | |
8c8bf09f ASL |
247 | } |
248 | } | |
249 | ||
1f506a43 FC |
250 | /* |
251 | * (non-Javadoc) | |
252 | * | |
4ab33d2b AO |
253 | * @see java.lang.Object#equals(java.lang.Object) |
254 | */ | |
8c8bf09f | 255 | @Override |
8c8bf09f | 256 | public boolean equals(Object other) { |
4ab33d2b AO |
257 | if (other instanceof TmfTimestamp) |
258 | return compareTo((TmfTimestamp) other, false) == 0; | |
259 | return super.equals(other); | |
8c8bf09f ASL |
260 | } |
261 | ||
1f506a43 FC |
262 | /* (non-Javadoc) |
263 | * @see java.lang.Object#toString() | |
264 | */ | |
265 | @Override | |
266 | public String toString() { | |
267 | return "[TmfTimestamp:" + fValue + "," + fScale + "," + fPrecision + "]"; | |
268 | } | |
269 | ||
8c8bf09f | 270 | } |