hrsw 0.1.2

This is a simple, high resolution stopwatch library.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304

//! Simple stopwatch implementation that can be used for high resolution time measurement.
//!
//! # Example
//!
//! ```no_run
//! use hrsw::Stopwatch;
//!
//! let mut stopwatch = Stopwatch::new();
//! stopwatch.start();
//! // do something and get the elapsed time
//! let elapsed = stopwatch.elapsed();
//! // do something other and get the total elapsed time
//! stopwatch.stop();
//! let total_elapsed = stopwatch.elapsed();
//! ```
use std::time::Duration;
use std::time::SystemTime;

#[derive(Clone, Copy, Debug)]
pub struct Stopwatch {
    start_time: Option<SystemTime>,
    elapsed_duration: Duration,
}

impl Stopwatch {
    /// Creates a Stopwatch.
    pub fn new() -> Stopwatch {
        Stopwatch {
            start_time: None,
            elapsed_duration: Duration::new(0, 0),
        }
    }

    /// Creates and immediately starts a Stopwatch.
    pub fn new_started() -> Stopwatch {
        let mut stopwatch = Stopwatch {
            start_time: None,
            elapsed_duration: Duration::new(0, 0),
        };
        stopwatch.start();
        stopwatch
    }

    /// Starts the measurement.
    /// If the stopwatch is already running, then the call has no effect.
    pub fn start(&mut self) {
        if self.start_time.is_none() {
            self.start_time = Some(SystemTime::now());
        }
    }

    /// Stops the measurement.
    /// The elapsed duration can be obtained using `elapsed()`. If the stopwatch has never been started or has already been stopped, then the call has no effect.
    pub fn stop(&mut self) {
        if self.start_time.is_some() {
            self.elapsed_duration = self.elapsed_duration
                + (SystemTime::now().duration_since(self.start_time.take().unwrap())).unwrap();
        }
    }

    /// Restores the original state of the stopwatch.
    /// If the stopwatch is running, then it will be stopped and the elapsed will be cleared, so it can't be obtained.
    pub fn reset(&mut self) {
        self.start_time = None;
        self.elapsed_duration = Duration::new(0, 0);
    }

    /// Restores the original state of the stopwatch and then starts the measurement.
    /// It is the same as calling `reset()` and `start()` in that sequence.
    pub fn reset_and_start(&mut self) {
        self.reset();
        self.start();
    }

    /// Returns the elapsed time. In case of multiple `start()` and `stop()` the elapsed intervals are accumulated. The elapsed time can be cleared by `reset()` or reset_and_start()`.
    pub fn elapsed(&self) -> Duration {
        match self.start_time {
            Some(t) => self.elapsed_duration + SystemTime::now().duration_since(t).unwrap(),
            None => self.elapsed_duration,
        }
    }

    /// Returns whether the stopwatch is running or not.
    pub fn is_running(&self) -> bool {
        self.start_time.is_some()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::thread;
    static DURATION_TO_USE: Duration = Duration::from_millis(400);
    static RELATIVE_TOLERANCE: f32 = 0.05;

    fn assert_eq_dur_with_min(measured: Duration, expected: Duration) {
        assert!(
            expected <= measured,
            "Expected: {}, measured: {}",
            expected.as_millis(),
            measured.as_millis()
        );
        let expected_maximum = expected.mul_f32(1.0 + RELATIVE_TOLERANCE);
        assert!(
            measured < expected_maximum,
            "Expected maximum: {}, measured: {}",
            expected_maximum.as_millis(),
            measured.as_millis()
        );
    }

    fn assert_eq_with_min(stopwatch: &Stopwatch, duration: Duration) {
        let elapsed = stopwatch.elapsed();
        assert_eq_dur_with_min(elapsed, duration);
    }

    #[test]
    fn simple_start_stop() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        thread::sleep(DURATION_TO_USE);
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
    }

    #[test]
    fn multiple_start() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        thread::sleep(DURATION_TO_USE);
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        thread::sleep(DURATION_TO_USE);
        assert_eq_with_min(&stopwatch, 2 * DURATION_TO_USE);
    }

    #[test]
    fn multiple_start_without_stop() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        thread::sleep(DURATION_TO_USE);
        assert_eq_with_min(&stopwatch, 3 * DURATION_TO_USE);
    }
    #[test]
    fn get_elapsed_multiple_times() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        thread::sleep(DURATION_TO_USE);
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
        thread::sleep(DURATION_TO_USE);
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
        assert_eq!(stopwatch.elapsed(), stopwatch.elapsed());
    }

    #[test]
    fn get_elapsed_without_stop() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        let elapsed = stopwatch.elapsed();
        assert_eq_dur_with_min(elapsed, DURATION_TO_USE);
    }

    #[test]
    fn reset_simple() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
        thread::sleep(DURATION_TO_USE);
        stopwatch.reset();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
    }

    #[test]
    fn reset_without_stop() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.reset();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
    }

    #[test]
    fn reset_and_start_simple() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.reset_and_start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
    }

    #[test]
    fn reset_and_start_after_stop() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        stopwatch.reset_and_start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        assert_eq_with_min(&stopwatch, DURATION_TO_USE);
    }

    #[test]
    fn reset_and_start_multiple_start() {
        let mut stopwatch = Stopwatch::new();
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.reset_and_start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.start();
        thread::sleep(DURATION_TO_USE);
        stopwatch.stop();
        assert_eq_with_min(&stopwatch, 2 * DURATION_TO_USE);
    }

    #[test]
    fn is_running_simple() {
        let mut stopwatch = Stopwatch::new();
        assert!(!stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.stop();
        assert!(!stopwatch.is_running());
    }

    #[test]
    fn is_running_multiple_start() {
        let mut stopwatch = Stopwatch::new();
        assert!(!stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.stop();
        assert!(!stopwatch.is_running());
    }

    #[test]
    fn is_running_after_reset() {
        let mut stopwatch = Stopwatch::new();
        assert!(!stopwatch.is_running());
        stopwatch.start();
        stopwatch.reset();
        assert!(!stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.stop();
        assert!(!stopwatch.is_running());
    }

    #[test]
    fn is_running_complex_scenario() {
        let mut stopwatch = Stopwatch::new();
        assert!(!stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.reset();
        assert!(!stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.reset_and_start();
        assert!(stopwatch.is_running());
    }

    #[test]
    fn is_running_after_reset_and_start() {
        let mut stopwatch = Stopwatch::new();
        assert!(!stopwatch.is_running());
        stopwatch.start();
        stopwatch.reset_and_start();
        assert!(stopwatch.is_running());
        stopwatch.start();
        assert!(stopwatch.is_running());
        stopwatch.stop();
        assert!(!stopwatch.is_running());
    }
}