k8s.io/apiserver@v0.31.1/pkg/util/flowcontrol/request/seat_seconds.go (about)

     1  /*
     2  Copyright 2021 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package request
    18  
    19  import (
    20  	"fmt"
    21  	"math"
    22  	"time"
    23  )
    24  
    25  // SeatSeconds is a measure of work, in units of seat-seconds, using a fixed-point representation.
    26  // `SeatSeconds(n)` represents `n/ssScale` seat-seconds.
    27  // The `ssScale` constant is private to the implementation here,
    28  // no other code should use it.
    29  type SeatSeconds uint64
    30  
    31  // MaxSeatsSeconds is the maximum representable value of SeatSeconds
    32  const MaxSeatSeconds = SeatSeconds(math.MaxUint64)
    33  
    34  // MinSeatSeconds is the lowest representable value of SeatSeconds
    35  const MinSeatSeconds = SeatSeconds(0)
    36  
    37  // SeatsTimeDuration produces the SeatSeconds value for the given factors.
    38  // This is intended only to produce small values, increments in work
    39  // rather than amount of work done since process start.
    40  func SeatsTimesDuration(seats float64, duration time.Duration) SeatSeconds {
    41  	return SeatSeconds(int64(math.Round(seats * float64(duration/time.Nanosecond) / (1e9 / ssScale))))
    42  }
    43  
    44  // ToFloat converts to a floating-point representation.
    45  // This conversion may lose precision.
    46  func (ss SeatSeconds) ToFloat() float64 {
    47  	return float64(ss) / ssScale
    48  }
    49  
    50  // DurationPerSeat returns duration per seat.
    51  // This division may lose precision.
    52  func (ss SeatSeconds) DurationPerSeat(seats float64) time.Duration {
    53  	return time.Duration(float64(ss) / seats * (float64(time.Second) / ssScale))
    54  }
    55  
    56  // String converts to a string.
    57  // This is suitable for large as well as small values.
    58  func (ss SeatSeconds) String() string {
    59  	const div = SeatSeconds(ssScale)
    60  	quo := ss / div
    61  	rem := ss - quo*div
    62  	return fmt.Sprintf("%d.%08dss", quo, rem)
    63  }
    64  
    65  const ssScale = 1e8