github.com/m3db/m3@v1.5.0/src/metrics/transformation/unary.go (about)

     1  // Copyright (c) 2018 Uber Technologies, Inc.
     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 deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // 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 FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package transformation
    22  
    23  import "math"
    24  
    25  var (
    26  	// allows to use a single transform fn ref (instead of
    27  	// taking reference to it each time when converting to iface).
    28  	transformAbsoluteFn = UnaryTransformFn(absolute)
    29  )
    30  
    31  func transformAbsolute() UnaryTransform {
    32  	return transformAbsoluteFn
    33  }
    34  
    35  func absolute(dp Datapoint) Datapoint {
    36  	var res Datapoint
    37  	res.TimeNanos = dp.TimeNanos
    38  	res.Value = math.Abs(dp.Value)
    39  	return res
    40  }
    41  
    42  // add will add add a datapoint to a running count and return the result, useful
    43  // for computing a running sum of values (like a monotonic increasing counter).
    44  // Note:
    45  // * It treats NaN as zero value, i.e. 42 + NaN = 42.
    46  func transformAdd() UnaryTransform {
    47  	var curr float64
    48  	return UnaryTransformFn(func(dp Datapoint) Datapoint {
    49  		if !math.IsNaN(dp.Value) {
    50  			curr += dp.Value
    51  		}
    52  		return Datapoint{TimeNanos: dp.TimeNanos, Value: curr}
    53  	})
    54  }