go.mway.dev/chrono@v0.6.1-0.20240126030049-189c5aef20d2/rate/recorder.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 rate
    22  
    23  import (
    24  	"time"
    25  
    26  	"go.mway.dev/chrono/clock"
    27  	"go.uber.org/atomic"
    28  )
    29  
    30  // A Recorder records added counts and reports the rate of the total count over
    31  // the elapsed time.
    32  type Recorder struct {
    33  	clock clock.Clock
    34  	count atomic.Int64
    35  	epoch atomic.Int64
    36  }
    37  
    38  // NewRecorder creates a new [Recorder] that uses the system's monotonic clock.
    39  func NewRecorder() *Recorder {
    40  	return NewRecorderWithClock(clock.NewMonotonicClock())
    41  }
    42  
    43  // NewRecorderWithClock returns a new [Recorder] that uses the given clock.
    44  func NewRecorderWithClock(clk clock.Clock) *Recorder {
    45  	r := &Recorder{
    46  		clock: clk,
    47  	}
    48  	r.Reset()
    49  	return r
    50  }
    51  
    52  // Add adds n to the running count.
    53  func (r *Recorder) Add(n int) {
    54  	r.count.Add(int64(n))
    55  }
    56  
    57  // Rate returns a [Rate] that represents the running count and time elapsed
    58  // since the recorder's clock started.
    59  func (r *Recorder) Rate() Rate {
    60  	return Rate{
    61  		count:   r.count.Load(),
    62  		elapsed: r.clock.SinceNanotime(r.epoch.Load()),
    63  	}
    64  }
    65  
    66  // Reset returns the current [Rate] and resets the recorder's running count and
    67  // epoch.
    68  func (r *Recorder) Reset() Rate {
    69  	var (
    70  		now     = r.clock.Nanotime()
    71  		elapsed = time.Duration(now - r.epoch.Swap(now))
    72  	)
    73  	return Rate{
    74  		count:   r.count.Swap(0),
    75  		elapsed: elapsed,
    76  	}
    77  }
    78  
    79  // A Rate is a count over a period of time.
    80  type Rate struct {
    81  	count   int64
    82  	elapsed time.Duration
    83  }
    84  
    85  // Per returns the rate's count over the given period of time.
    86  func (r Rate) Per(d time.Duration) float64 {
    87  	return (float64(r.count) / float64(r.elapsed)) * float64(d)
    88  }