001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.lang.time;
019
020 /**
021 * <p>
022 * <code>StopWatch</code> provides a convenient API for timings.
023 * </p>
024 *
025 * <p>
026 * To start the watch, call {@link #start()}. At this point you can:
027 * </p>
028 * <ul>
029 * <li>{@link #split()} the watch to get the time whilst the watch continues in the background. {@link #unsplit()} will
030 * remove the effect of the split. At this point, these three options are available again.</li>
031 * <li>{@link #suspend()} the watch to pause it. {@link #resume()} allows the watch to continue. Any time between the
032 * suspend and resume will not be counted in the total. At this point, these three options are available again.</li>
033 * <li>{@link #stop()} the watch to complete the timing session.</li>
034 * </ul>
035 *
036 * <p>
037 * It is intended that the output methods {@link #toString()} and {@link #getTime()} should only be called after stop,
038 * split or suspend, however a suitable result will be returned at other points.
039 * </p>
040 *
041 * <p>
042 * NOTE: As from v2.1, the methods protect against inappropriate calls. Thus you cannot now call stop before start,
043 * resume before suspend or unsplit before split.
044 * </p>
045 *
046 * <p>
047 * 1. split(), suspend(), or stop() cannot be invoked twice<br />
048 * 2. unsplit() may only be called if the watch has been split()<br />
049 * 3. resume() may only be called if the watch has been suspend()<br />
050 * 4. start() cannot be called twice without calling reset()
051 * </p>
052 *
053 * <p>This class is not thread-safe</p>
054 *
055 * @author Apache Software Foundation
056 * @since 2.0
057 * @version $Id: StopWatch.java 1056988 2011-01-09 17:58:53Z niallp $
058 */
059 public class StopWatch {
060
061 // running states
062 private static final int STATE_UNSTARTED = 0;
063
064 private static final int STATE_RUNNING = 1;
065
066 private static final int STATE_STOPPED = 2;
067
068 private static final int STATE_SUSPENDED = 3;
069
070 // split state
071 private static final int STATE_UNSPLIT = 10;
072
073 private static final int STATE_SPLIT = 11;
074
075 /**
076 * The current running state of the StopWatch.
077 */
078 private int runningState = STATE_UNSTARTED;
079
080 /**
081 * Whether the stopwatch has a split time recorded.
082 */
083 private int splitState = STATE_UNSPLIT;
084
085 /**
086 * The start time.
087 */
088 private long startTime = -1;
089
090 /**
091 * The stop time.
092 */
093 private long stopTime = -1;
094
095 /**
096 * <p>
097 * Constructor.
098 * </p>
099 */
100 public StopWatch() {
101 super();
102 }
103
104 /**
105 * <p>
106 * Start the stopwatch.
107 * </p>
108 *
109 * <p>
110 * This method starts a new timing session, clearing any previous values.
111 * </p>
112 *
113 * @throws IllegalStateException
114 * if the StopWatch is already running.
115 */
116 public void start() {
117 if (this.runningState == STATE_STOPPED) {
118 throw new IllegalStateException("Stopwatch must be reset before being restarted. ");
119 }
120 if (this.runningState != STATE_UNSTARTED) {
121 throw new IllegalStateException("Stopwatch already started. ");
122 }
123 this.stopTime = -1;
124 this.startTime = System.currentTimeMillis();
125 this.runningState = STATE_RUNNING;
126 }
127
128 /**
129 * <p>
130 * Stop the stopwatch.
131 * </p>
132 *
133 * <p>
134 * This method ends a new timing session, allowing the time to be retrieved.
135 * </p>
136 *
137 * @throws IllegalStateException
138 * if the StopWatch is not running.
139 */
140 public void stop() {
141 if (this.runningState != STATE_RUNNING && this.runningState != STATE_SUSPENDED) {
142 throw new IllegalStateException("Stopwatch is not running. ");
143 }
144 if (this.runningState == STATE_RUNNING) {
145 this.stopTime = System.currentTimeMillis();
146 }
147 this.runningState = STATE_STOPPED;
148 }
149
150 /**
151 * <p>
152 * Resets the stopwatch. Stops it if need be.
153 * </p>
154 *
155 * <p>
156 * This method clears the internal values to allow the object to be reused.
157 * </p>
158 */
159 public void reset() {
160 this.runningState = STATE_UNSTARTED;
161 this.splitState = STATE_UNSPLIT;
162 this.startTime = -1;
163 this.stopTime = -1;
164 }
165
166 /**
167 * <p>
168 * Split the time.
169 * </p>
170 *
171 * <p>
172 * This method sets the stop time of the watch to allow a time to be extracted. The start time is unaffected,
173 * enabling {@link #unsplit()} to continue the timing from the original start point.
174 * </p>
175 *
176 * @throws IllegalStateException
177 * if the StopWatch is not running.
178 */
179 public void split() {
180 if (this.runningState != STATE_RUNNING) {
181 throw new IllegalStateException("Stopwatch is not running. ");
182 }
183 this.stopTime = System.currentTimeMillis();
184 this.splitState = STATE_SPLIT;
185 }
186
187 /**
188 * <p>
189 * Remove a split.
190 * </p>
191 *
192 * <p>
193 * This method clears the stop time. The start time is unaffected, enabling timing from the original start point to
194 * continue.
195 * </p>
196 *
197 * @throws IllegalStateException
198 * if the StopWatch has not been split.
199 */
200 public void unsplit() {
201 if (this.splitState != STATE_SPLIT) {
202 throw new IllegalStateException("Stopwatch has not been split. ");
203 }
204 this.stopTime = -1;
205 this.splitState = STATE_UNSPLIT;
206 }
207
208 /**
209 * <p>
210 * Suspend the stopwatch for later resumption.
211 * </p>
212 *
213 * <p>
214 * This method suspends the watch until it is resumed. The watch will not include time between the suspend and
215 * resume calls in the total time.
216 * </p>
217 *
218 * @throws IllegalStateException
219 * if the StopWatch is not currently running.
220 */
221 public void suspend() {
222 if (this.runningState != STATE_RUNNING) {
223 throw new IllegalStateException("Stopwatch must be running to suspend. ");
224 }
225 this.stopTime = System.currentTimeMillis();
226 this.runningState = STATE_SUSPENDED;
227 }
228
229 /**
230 * <p>
231 * Resume the stopwatch after a suspend.
232 * </p>
233 *
234 * <p>
235 * This method resumes the watch after it was suspended. The watch will not include time between the suspend and
236 * resume calls in the total time.
237 * </p>
238 *
239 * @throws IllegalStateException
240 * if the StopWatch has not been suspended.
241 */
242 public void resume() {
243 if (this.runningState != STATE_SUSPENDED) {
244 throw new IllegalStateException("Stopwatch must be suspended to resume. ");
245 }
246 this.startTime += (System.currentTimeMillis() - this.stopTime);
247 this.stopTime = -1;
248 this.runningState = STATE_RUNNING;
249 }
250
251 /**
252 * <p>
253 * Get the time on the stopwatch.
254 * </p>
255 *
256 * <p>
257 * This is either the time between the start and the moment this method is called, or the amount of time between
258 * start and stop.
259 * </p>
260 *
261 * @return the time in milliseconds
262 */
263 public long getTime() {
264 if (this.runningState == STATE_STOPPED || this.runningState == STATE_SUSPENDED) {
265 return this.stopTime - this.startTime;
266 } else if (this.runningState == STATE_UNSTARTED) {
267 return 0;
268 } else if (this.runningState == STATE_RUNNING) {
269 return System.currentTimeMillis() - this.startTime;
270 }
271 throw new RuntimeException("Illegal running state has occured. ");
272 }
273
274 /**
275 * <p>
276 * Get the split time on the stopwatch.
277 * </p>
278 *
279 * <p>
280 * This is the time between start and latest split.
281 * </p>
282 *
283 * @return the split time in milliseconds
284 *
285 * @throws IllegalStateException
286 * if the StopWatch has not yet been split.
287 * @since 2.1
288 */
289 public long getSplitTime() {
290 if (this.splitState != STATE_SPLIT) {
291 throw new IllegalStateException("Stopwatch must be split to get the split time. ");
292 }
293 return this.stopTime - this.startTime;
294 }
295
296 /**
297 * Returns the time this stopwatch was started.
298 *
299 * @return the time this stopwatch was started
300 * @throws IllegalStateException
301 * if this StopWatch has not been started
302 * @since 2.4
303 */
304 public long getStartTime() {
305 if (this.runningState == STATE_UNSTARTED) {
306 throw new IllegalStateException("Stopwatch has not been started");
307 }
308 return this.startTime;
309 }
310
311 /**
312 * <p>
313 * Gets a summary of the time that the stopwatch recorded as a string.
314 * </p>
315 *
316 * <p>
317 * The format used is ISO8601-like, <i>hours</i>:<i>minutes</i>:<i>seconds</i>.<i>milliseconds</i>.
318 * </p>
319 *
320 * @return the time as a String
321 */
322 public String toString() {
323 return DurationFormatUtils.formatDurationHMS(getTime());
324 }
325
326 /**
327 * <p>
328 * Gets a summary of the split time that the stopwatch recorded as a string.
329 * </p>
330 *
331 * <p>
332 * The format used is ISO8601-like, <i>hours</i>:<i>minutes</i>:<i>seconds</i>.<i>milliseconds</i>.
333 * </p>
334 *
335 * @return the split time as a String
336 * @since 2.1
337 */
338 public String toSplitString() {
339 return DurationFormatUtils.formatDurationHMS(getSplitTime());
340 }
341
342 }