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 | ||
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); |
e31e01e8 | 56 | public static final TmfTimestamp Zero = new TmfTimestamp(0, (byte) 0, 0); |
8c8bf09f | 57 | |
4ab33d2b | 58 | // ======================================================================== |
8c8bf09f | 59 | // Constructors |
4ab33d2b | 60 | // ======================================================================== |
8c8bf09f ASL |
61 | |
62 | /** | |
28b94d61 | 63 | * Default constructor |
8c8bf09f ASL |
64 | */ |
65 | public TmfTimestamp() { | |
66 | this(0, (byte) 0, 0); | |
67 | } | |
68 | ||
1f506a43 | 69 | /** |
28b94d61 | 70 | * Simple constructor with value only |
1f506a43 FC |
71 | */ |
72 | public TmfTimestamp(long value) { | |
73 | this(value, (byte) 0, 0); | |
74 | } | |
75 | ||
8c8bf09f | 76 | /** |
28b94d61 | 77 | * Simple constructor with value and scale |
8c8bf09f | 78 | * |
1f506a43 FC |
79 | * @param value |
80 | * @param scale | |
8c8bf09f ASL |
81 | */ |
82 | public TmfTimestamp(long value, byte scale) { | |
83 | this(value, scale, 0); | |
84 | } | |
85 | ||
86 | /** | |
28b94d61 | 87 | * Constructor with value, scale and precision |
8c8bf09f | 88 | * |
1f506a43 FC |
89 | * @param value |
90 | * @param scale | |
91 | * @param precision | |
8c8bf09f ASL |
92 | */ |
93 | public TmfTimestamp(long value, byte scale, long precision) { | |
94 | fValue = value; | |
95 | fScale = scale; | |
96 | fPrecision = Math.abs(precision); | |
97 | } | |
98 | ||
99 | /** | |
28b94d61 | 100 | * Copy constructor |
8c8bf09f | 101 | * |
1f506a43 | 102 | * @param other |
8c8bf09f ASL |
103 | */ |
104 | public TmfTimestamp(TmfTimestamp other) { | |
28b94d61 FC |
105 | assert(other != null); |
106 | fValue = other.fValue; | |
107 | fScale = other.fScale; | |
108 | fPrecision = other.fPrecision; | |
8c8bf09f ASL |
109 | } |
110 | ||
4ab33d2b | 111 | // ======================================================================== |
8c8bf09f | 112 | // Accessors |
4ab33d2b | 113 | // ======================================================================== |
8c8bf09f ASL |
114 | |
115 | /** | |
28b94d61 | 116 | * @return the timestamp value |
8c8bf09f ASL |
117 | */ |
118 | public long getValue() { | |
119 | return fValue; | |
120 | } | |
121 | ||
122 | /** | |
28b94d61 | 123 | * @return the timestamp scale |
8c8bf09f ASL |
124 | */ |
125 | public byte getScale() { | |
126 | return fScale; | |
127 | } | |
128 | ||
129 | /** | |
28b94d61 | 130 | * @return the timestamp value precision |
8c8bf09f ASL |
131 | */ |
132 | public long getPrecision() { | |
133 | return fPrecision; | |
134 | } | |
135 | ||
4ab33d2b | 136 | // ======================================================================== |
8c8bf09f | 137 | // Operators |
4ab33d2b AO |
138 | // ======================================================================== |
139 | ||
8c8bf09f ASL |
140 | /** |
141 | * Return a shifted and scaled timestamp. | |
142 | * | |
143 | * Limitation: The scaling is limited to MAX_SCALING orders of magnitude. | |
144 | * The main reason is that the 64 bits value starts to lose any significance | |
145 | * meaning beyond that scale difference and it's not even worth the trouble | |
146 | * to switch to BigDecimal arithmetics. | |
147 | * | |
1f506a43 FC |
148 | * @param offset |
149 | * - the shift value (in the same scale as newScale) | |
150 | * @param newScale | |
151 | * - the new scale | |
152 | * @return The synchronized timestamp | |
8c8bf09f | 153 | */ |
8c8bf09f | 154 | |
4ab33d2b AO |
155 | /* |
156 | * A java <code>long</code> has a maximum of 19 significant digits. | |
157 | * (-9,223,372,036,854,775,808 .. +9,223,372,036,854,775,807) | |
158 | * | |
159 | * It is therefore useless to try to synchronize 2 timestamps whose | |
160 | * difference in scale exceeds that value. | |
161 | */ | |
162 | private static int MAX_SCALING = 19; | |
1f506a43 | 163 | |
4ab33d2b AO |
164 | public TmfTimestamp synchronize(long offset, byte newScale) throws ArithmeticException { |
165 | long newValue = fValue; | |
8c8bf09f ASL |
166 | long newPrecision = fPrecision; |
167 | ||
168 | // Determine the scaling factor | |
169 | if (fScale != newScale) { | |
170 | int scaleDiff = Math.abs(fScale - newScale); | |
171 | // Let's try to be realistic... | |
172 | if (scaleDiff > MAX_SCALING) { | |
173 | throw new ArithmeticException("Scaling exception"); | |
174 | } | |
1f506a43 | 175 | // Not pretty... |
8c8bf09f | 176 | long scalingFactor = 1; |
1f506a43 | 177 | for (int i = 0; i < scaleDiff; i++) { |
8c8bf09f ASL |
178 | scalingFactor *= 10; |
179 | } | |
180 | if (newScale < fScale) { | |
181 | newValue *= scalingFactor; | |
182 | newPrecision *= scalingFactor; | |
183 | } else { | |
184 | newValue /= scalingFactor; | |
185 | newPrecision /= scalingFactor; | |
186 | } | |
187 | } | |
188 | ||
189 | return new TmfTimestamp(newValue + offset, newScale, newPrecision); | |
190 | } | |
191 | ||
192 | /** | |
193 | * Compute the adjustment, in the reference scale, needed to synchronize | |
1f506a43 | 194 | * this timestamp with a reference timestamp. |
8c8bf09f | 195 | * |
1f506a43 FC |
196 | * @param reference |
197 | * - the reference timestamp to synchronize with | |
28b94d61 | 198 | * @return the adjustment term in the reference time scale |
4ab33d2b | 199 | * @throws TmfNumericalException |
8c8bf09f | 200 | */ |
4ab33d2b AO |
201 | public long getAdjustment(TmfTimestamp reference) throws ArithmeticException { |
202 | TmfTimestamp ts = synchronize(0, reference.fScale); | |
203 | return reference.fValue - ts.fValue; | |
8c8bf09f ASL |
204 | } |
205 | ||
206 | /** | |
207 | * Compare with another timestamp | |
208 | * | |
1f506a43 FC |
209 | * @param other |
210 | * - the other timestamp | |
211 | * @param withinPrecision | |
212 | * - indicates if precision is to be take into consideration | |
28b94d61 FC |
213 | * @return -1: this timestamp is lower |
214 | * 0: timestamps are equal (within precision if requested) | |
215 | * 1: this timestamp is higher | |
4ab33d2b | 216 | * @throws TmfNumericalException |
8c8bf09f ASL |
217 | */ |
218 | public int compareTo(final TmfTimestamp other, boolean withinPrecision) { | |
219 | ||
62d1696a | 220 | // If values have the same time scale, perform the comparison |
8c8bf09f ASL |
221 | if (fScale == other.fScale) { |
222 | if (withinPrecision) { | |
223 | if ((fValue + fPrecision) < (other.fValue - other.fPrecision)) | |
224 | return -1; | |
225 | if ((fValue - fPrecision) > (other.fValue + other.fPrecision)) | |
226 | return 1; | |
227 | return 0; | |
228 | } | |
1f506a43 FC |
229 | return (fValue == other.fValue) ? 0 : (fValue < other.fValue) ? -1 |
230 | : 1; | |
8c8bf09f ASL |
231 | } |
232 | ||
233 | // If values have different time scales, adjust to the finest one and | |
234 | // then compare. If the scaling difference is too large, revert to | |
235 | // some heuristics. Hopefully, nobody will try to compare galactic and | |
62d1696a | 236 | // quantic clock events... |
8c8bf09f ASL |
237 | byte newScale = (fScale < other.fScale) ? fScale : other.fScale; |
238 | try { | |
239 | TmfTimestamp ts1 = this.synchronize(0, newScale); | |
240 | TmfTimestamp ts2 = other.synchronize(0, newScale); | |
241 | return ts1.compareTo(ts2, withinPrecision); | |
242 | } catch (ArithmeticException e) { | |
4ab33d2b | 243 | if ((fValue == 0) || (other.fValue == 0)) { |
1f506a43 FC |
244 | return (fValue == other.fValue) ? 0 |
245 | : (fValue < other.fValue) ? -1 : 1; | |
4ab33d2b AO |
246 | } |
247 | if ((fValue > 0) && (other.fValue > 0)) { | |
248 | return (fScale < other.fScale) ? -1 : 1; | |
249 | } | |
250 | if ((fValue < 0) && (other.fValue < 0)) { | |
251 | return (fScale > other.fScale) ? -1 : 1; | |
252 | } | |
253 | return (fValue < 0) ? -1 : 1; | |
8c8bf09f ASL |
254 | } |
255 | } | |
256 | ||
28b94d61 FC |
257 | @Override |
258 | public TmfTimestamp clone() { | |
259 | return new TmfTimestamp(this); | |
260 | } | |
261 | ||
8c8bf09f | 262 | @Override |
8c8bf09f | 263 | public boolean equals(Object other) { |
4ab33d2b AO |
264 | if (other instanceof TmfTimestamp) |
265 | return compareTo((TmfTimestamp) other, false) == 0; | |
266 | return super.equals(other); | |
8c8bf09f ASL |
267 | } |
268 | ||
1f506a43 FC |
269 | @Override |
270 | public String toString() { | |
28b94d61 | 271 | return "[TmfTimestamp(" + fValue + "," + fScale + "," + fPrecision + ")]"; |
1f506a43 FC |
272 | } |
273 | ||
8c8bf09f | 274 | } |