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binary.go
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binary.go
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// Copyright (c) 2018 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package transformation
import (
"math"
"time"
)
const (
nanosPerSecond = time.Second / time.Nanosecond
)
var (
// allows to use a single transform fn ref (instead of
// taking reference to it each time when converting to iface).
transformPerSecondFn = BinaryTransformFn(perSecond)
transformIncreaseFn = BinaryTransformFn(increase)
)
func transformPerSecond() BinaryTransform {
return transformPerSecondFn
}
// perSecond computes the derivative between consecutive datapoints, taking into
// account the time interval between the values.
// Note:
// * It skips NaN values.
// * It assumes the timestamps are monotonically increasing, and values are non-decreasing.
// If either of the two conditions is not met, an empty datapoint is returned.
func perSecond(prev, curr Datapoint) Datapoint {
if prev.TimeNanos >= curr.TimeNanos || math.IsNaN(prev.Value) || math.IsNaN(curr.Value) {
return emptyDatapoint
}
diff := curr.Value - prev.Value
if diff < 0 {
return emptyDatapoint
}
rate := diff * float64(nanosPerSecond) / float64(curr.TimeNanos-prev.TimeNanos)
return Datapoint{TimeNanos: curr.TimeNanos, Value: rate}
}
func transformIncrease() BinaryTransform {
return transformIncreaseFn
}
// increase computes the difference between consecutive datapoints, unlike
// perSecond it does not account for the time interval between the values.
// Note:
// * It skips NaN values.
// * It assumes the timestamps are monotonically increasing, and values are non-decreasing.
// If either of the two conditions is not met, an empty datapoint is returned.
func increase(prev, curr Datapoint) Datapoint {
if prev.TimeNanos >= curr.TimeNanos || math.IsNaN(prev.Value) || math.IsNaN(curr.Value) {
return emptyDatapoint
}
diff := curr.Value - prev.Value
if diff < 0 {
return emptyDatapoint
}
return Datapoint{TimeNanos: curr.TimeNanos, Value: diff}
}