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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 | ||
98029bc9 | 15 | |
8c8bf09f ASL |
16 | /** |
17 | * <b><u>TmfTimestamp</u></b> | |
18 | * <p> | |
19 | * The fundamental time reference in the TMF. | |
20 | * <p> | |
21 | * It provides a generic timestamp implementation in its most basic form: | |
22 | * <ul> | |
1f506a43 FC |
23 | * <li>an unstructured integer value |
24 | * <li>a time scale corresponding to the magnitude of the value wrt some | |
25 | * application-specific base unit (e.g. the second) | |
26 | * <li>a precision to indicate the error on the value (useful for comparing | |
27 | * timestamps in different scales). Default: 0. | |
8c8bf09f | 28 | * </ul> |
28b94d61 FC |
29 | * To allow synchronization of timestamps from different reference clocks, |
30 | * there is a possibility to "adjust" the timestamp both by changing its scale | |
31 | * (traces of different scale) and by adding an offset to its value (clock | |
32 | * drift between traces). | |
8c8bf09f | 33 | * <p> |
28b94d61 FC |
34 | * Notice that the adjusted timestamp value could be negative e.g. for events |
35 | * that occurred before t0 wrt the reference clock. | |
36 | * <p> | |
37 | * Finally, notice that timestamps are immutable. | |
8c8bf09f | 38 | */ |
28b94d61 | 39 | public class TmfTimestamp implements Cloneable { |
98029bc9 FC |
40 | |
41 | // ======================================================================== | |
8c8bf09f | 42 | // Attributes |
4ab33d2b | 43 | // ======================================================================== |
8c8bf09f | 44 | |
28b94d61 FC |
45 | protected long fValue; // The timestamp value |
46 | protected byte fScale; // The time scale | |
47 | protected long fPrecision; // The value precision (tolerance) | |
8c8bf09f | 48 | |
4ab33d2b | 49 | // ======================================================================== |
8c8bf09f | 50 | // Constants |
4ab33d2b | 51 | // ======================================================================== |
8c8bf09f ASL |
52 | |
53 | // The beginning and end of time | |
146a887c | 54 | public static final TmfTimestamp BigBang = new TmfTimestamp(Long.MIN_VALUE, Byte.MAX_VALUE, 0); |
8c8bf09f | 55 | public static final TmfTimestamp BigCrunch = new TmfTimestamp(Long.MAX_VALUE, Byte.MAX_VALUE, 0); |
8c8bf09f | 56 | |
4ab33d2b | 57 | // ======================================================================== |
8c8bf09f | 58 | // Constructors |
4ab33d2b | 59 | // ======================================================================== |
8c8bf09f ASL |
60 | |
61 | /** | |
28b94d61 | 62 | * Default constructor |
8c8bf09f ASL |
63 | */ |
64 | public TmfTimestamp() { | |
65 | this(0, (byte) 0, 0); | |
66 | } | |
67 | ||
1f506a43 | 68 | /** |
28b94d61 | 69 | * Simple constructor with value only |
1f506a43 FC |
70 | */ |
71 | public TmfTimestamp(long value) { | |
72 | this(value, (byte) 0, 0); | |
73 | } | |
74 | ||
8c8bf09f | 75 | /** |
28b94d61 | 76 | * Simple constructor with value and scale |
8c8bf09f | 77 | * |
1f506a43 FC |
78 | * @param value |
79 | * @param scale | |
8c8bf09f ASL |
80 | */ |
81 | public TmfTimestamp(long value, byte scale) { | |
82 | this(value, scale, 0); | |
83 | } | |
84 | ||
85 | /** | |
28b94d61 | 86 | * Constructor with value, scale and precision |
8c8bf09f | 87 | * |
1f506a43 FC |
88 | * @param value |
89 | * @param scale | |
90 | * @param precision | |
8c8bf09f ASL |
91 | */ |
92 | public TmfTimestamp(long value, byte scale, long precision) { | |
93 | fValue = value; | |
94 | fScale = scale; | |
95 | fPrecision = Math.abs(precision); | |
96 | } | |
97 | ||
98 | /** | |
28b94d61 | 99 | * Copy constructor |
8c8bf09f | 100 | * |
1f506a43 | 101 | * @param other |
8c8bf09f ASL |
102 | */ |
103 | public TmfTimestamp(TmfTimestamp other) { | |
28b94d61 FC |
104 | assert(other != null); |
105 | fValue = other.fValue; | |
106 | fScale = other.fScale; | |
107 | fPrecision = other.fPrecision; | |
8c8bf09f ASL |
108 | } |
109 | ||
4ab33d2b | 110 | // ======================================================================== |
8c8bf09f | 111 | // Accessors |
4ab33d2b | 112 | // ======================================================================== |
8c8bf09f ASL |
113 | |
114 | /** | |
28b94d61 | 115 | * @return the timestamp value |
8c8bf09f ASL |
116 | */ |
117 | public long getValue() { | |
118 | return fValue; | |
119 | } | |
120 | ||
121 | /** | |
28b94d61 | 122 | * @return the timestamp scale |
8c8bf09f ASL |
123 | */ |
124 | public byte getScale() { | |
125 | return fScale; | |
126 | } | |
127 | ||
128 | /** | |
28b94d61 | 129 | * @return the timestamp value precision |
8c8bf09f ASL |
130 | */ |
131 | public long getPrecision() { | |
132 | return fPrecision; | |
133 | } | |
134 | ||
4ab33d2b | 135 | // ======================================================================== |
8c8bf09f | 136 | // Operators |
4ab33d2b AO |
137 | // ======================================================================== |
138 | ||
8c8bf09f ASL |
139 | /** |
140 | * Return a shifted and scaled timestamp. | |
141 | * | |
142 | * Limitation: The scaling is limited to MAX_SCALING orders of magnitude. | |
143 | * The main reason is that the 64 bits value starts to lose any significance | |
144 | * meaning beyond that scale difference and it's not even worth the trouble | |
145 | * to switch to BigDecimal arithmetics. | |
146 | * | |
1f506a43 FC |
147 | * @param offset |
148 | * - the shift value (in the same scale as newScale) | |
149 | * @param newScale | |
150 | * - the new scale | |
151 | * @return The synchronized timestamp | |
8c8bf09f | 152 | */ |
8c8bf09f | 153 | |
4ab33d2b AO |
154 | /* |
155 | * A java <code>long</code> has a maximum of 19 significant digits. | |
156 | * (-9,223,372,036,854,775,808 .. +9,223,372,036,854,775,807) | |
157 | * | |
158 | * It is therefore useless to try to synchronize 2 timestamps whose | |
159 | * difference in scale exceeds that value. | |
160 | */ | |
161 | private static int MAX_SCALING = 19; | |
1f506a43 | 162 | |
4ab33d2b AO |
163 | public TmfTimestamp synchronize(long offset, byte newScale) throws ArithmeticException { |
164 | long newValue = fValue; | |
8c8bf09f ASL |
165 | long newPrecision = fPrecision; |
166 | ||
167 | // Determine the scaling factor | |
168 | if (fScale != newScale) { | |
169 | int scaleDiff = Math.abs(fScale - newScale); | |
170 | // Let's try to be realistic... | |
171 | if (scaleDiff > MAX_SCALING) { | |
172 | throw new ArithmeticException("Scaling exception"); | |
173 | } | |
1f506a43 | 174 | // Not pretty... |
8c8bf09f | 175 | long scalingFactor = 1; |
1f506a43 | 176 | for (int i = 0; i < scaleDiff; i++) { |
8c8bf09f ASL |
177 | scalingFactor *= 10; |
178 | } | |
179 | if (newScale < fScale) { | |
180 | newValue *= scalingFactor; | |
181 | newPrecision *= scalingFactor; | |
182 | } else { | |
183 | newValue /= scalingFactor; | |
184 | newPrecision /= scalingFactor; | |
185 | } | |
186 | } | |
187 | ||
188 | return new TmfTimestamp(newValue + offset, newScale, newPrecision); | |
189 | } | |
190 | ||
191 | /** | |
192 | * Compute the adjustment, in the reference scale, needed to synchronize | |
1f506a43 | 193 | * this timestamp with a reference timestamp. |
8c8bf09f | 194 | * |
1f506a43 FC |
195 | * @param reference |
196 | * - the reference timestamp to synchronize with | |
28b94d61 | 197 | * @return the adjustment term in the reference time scale |
4ab33d2b | 198 | * @throws TmfNumericalException |
8c8bf09f | 199 | */ |
4ab33d2b AO |
200 | public long getAdjustment(TmfTimestamp reference) throws ArithmeticException { |
201 | TmfTimestamp ts = synchronize(0, reference.fScale); | |
202 | return reference.fValue - ts.fValue; | |
8c8bf09f ASL |
203 | } |
204 | ||
205 | /** | |
206 | * Compare with another timestamp | |
207 | * | |
1f506a43 FC |
208 | * @param other |
209 | * - the other timestamp | |
210 | * @param withinPrecision | |
211 | * - indicates if precision is to be take into consideration | |
28b94d61 FC |
212 | * @return -1: this timestamp is lower |
213 | * 0: timestamps are equal (within precision if requested) | |
214 | * 1: this timestamp is higher | |
4ab33d2b | 215 | * @throws TmfNumericalException |
8c8bf09f ASL |
216 | */ |
217 | public int compareTo(final TmfTimestamp other, boolean withinPrecision) { | |
218 | ||
62d1696a | 219 | // If values have the same time scale, perform the comparison |
8c8bf09f ASL |
220 | if (fScale == other.fScale) { |
221 | if (withinPrecision) { | |
222 | if ((fValue + fPrecision) < (other.fValue - other.fPrecision)) | |
223 | return -1; | |
224 | if ((fValue - fPrecision) > (other.fValue + other.fPrecision)) | |
225 | return 1; | |
226 | return 0; | |
227 | } | |
1f506a43 FC |
228 | return (fValue == other.fValue) ? 0 : (fValue < other.fValue) ? -1 |
229 | : 1; | |
8c8bf09f ASL |
230 | } |
231 | ||
232 | // If values have different time scales, adjust to the finest one and | |
233 | // then compare. If the scaling difference is too large, revert to | |
234 | // some heuristics. Hopefully, nobody will try to compare galactic and | |
62d1696a | 235 | // quantic clock events... |
8c8bf09f ASL |
236 | byte newScale = (fScale < other.fScale) ? fScale : other.fScale; |
237 | try { | |
238 | TmfTimestamp ts1 = this.synchronize(0, newScale); | |
239 | TmfTimestamp ts2 = other.synchronize(0, newScale); | |
240 | return ts1.compareTo(ts2, withinPrecision); | |
241 | } catch (ArithmeticException e) { | |
4ab33d2b | 242 | if ((fValue == 0) || (other.fValue == 0)) { |
1f506a43 FC |
243 | return (fValue == other.fValue) ? 0 |
244 | : (fValue < other.fValue) ? -1 : 1; | |
4ab33d2b AO |
245 | } |
246 | if ((fValue > 0) && (other.fValue > 0)) { | |
247 | return (fScale < other.fScale) ? -1 : 1; | |
248 | } | |
249 | if ((fValue < 0) && (other.fValue < 0)) { | |
250 | return (fScale > other.fScale) ? -1 : 1; | |
251 | } | |
252 | return (fValue < 0) ? -1 : 1; | |
8c8bf09f ASL |
253 | } |
254 | } | |
255 | ||
28b94d61 FC |
256 | @Override |
257 | public TmfTimestamp clone() { | |
258 | return new TmfTimestamp(this); | |
259 | } | |
260 | ||
8c8bf09f | 261 | @Override |
8c8bf09f | 262 | public boolean equals(Object other) { |
4ab33d2b AO |
263 | if (other instanceof TmfTimestamp) |
264 | return compareTo((TmfTimestamp) other, false) == 0; | |
265 | return super.equals(other); | |
8c8bf09f ASL |
266 | } |
267 | ||
1f506a43 FC |
268 | @Override |
269 | public String toString() { | |
28b94d61 | 270 | return "[TmfTimestamp(" + fValue + "," + fScale + "," + fPrecision + ")]"; |
1f506a43 FC |
271 | } |
272 | ||
8c8bf09f | 273 | } |