go.mway.dev/chrono@v0.6.1-0.20240126030049-189c5aef20d2/clock/stopwatch.go (about)

     1  // Copyright (c) 2023 Matt Way
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to
     5  // deal in the Software without restriction, including without limitation the
     6  // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
     7  // sell copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    18  // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
    19  // IN THE THE SOFTWARE.
    20  
    21  package clock
    22  
    23  import "time"
    24  
    25  // A Stopwatch measures elapsed time. A Stopwatch is created by calling
    26  // [Clock.NewStopwatch].
    27  type Stopwatch struct {
    28  	clock Clock
    29  	epoch int64
    30  }
    31  
    32  func newStopwatch(clk Clock) *Stopwatch {
    33  	return &Stopwatch{
    34  		clock: clk,
    35  		epoch: clk.Nanotime(),
    36  	}
    37  }
    38  
    39  // Elapsed returns the time elapsed since the last call to [Stopwatch.Reset].
    40  func (s *Stopwatch) Elapsed() time.Duration {
    41  	return time.Duration(s.clock.Nanotime() - s.epoch)
    42  }
    43  
    44  // Reset resets the stopwatch to zero, returning the elapsed time since the
    45  // last call to Reset.
    46  func (s *Stopwatch) Reset() time.Duration {
    47  	var (
    48  		now     = s.clock.Nanotime()
    49  		elapsed = time.Duration(now - s.epoch)
    50  	)
    51  
    52  	s.epoch = now
    53  	return elapsed
    54  }