github.com/m3db/m3@v1.5.0/src/query/functions/linear/clamp.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 linear
    22  
    23  import (
    24  	"fmt"
    25  	"math"
    26  
    27  	"github.com/m3db/m3/src/query/block"
    28  	"github.com/m3db/m3/src/query/functions/lazy"
    29  	"github.com/m3db/m3/src/query/parser"
    30  )
    31  
    32  const (
    33  	// ClampMinType ensures all values except NaNs are greater
    34  	// than or equal to the provided argument.
    35  	ClampMinType = "clamp_min"
    36  
    37  	// ClampMaxType ensures all values except NaNs are lesser
    38  	// than or equal to provided argument.
    39  	ClampMaxType = "clamp_max"
    40  )
    41  
    42  type clampOp struct {
    43  	opType string
    44  	scalar float64
    45  }
    46  
    47  func parseClampArgs(args []interface{}) (float64, error) {
    48  	if len(args) != 1 {
    49  		return 0, fmt.Errorf("invalid number of args for clamp: %d", len(args))
    50  	}
    51  
    52  	scalar, ok := args[0].(float64)
    53  	if !ok {
    54  		return 0, fmt.Errorf("unable to cast to scalar argument: %v", args[0])
    55  	}
    56  
    57  	return scalar, nil
    58  }
    59  
    60  func clampFn(max bool, roundTo float64) block.ValueTransform {
    61  	if max {
    62  		return func(v float64) float64 { return math.Min(v, roundTo) }
    63  	}
    64  
    65  	return func(v float64) float64 { return math.Max(v, roundTo) }
    66  }
    67  
    68  func removeName(meta []block.SeriesMeta) []block.SeriesMeta {
    69  	for i, m := range meta {
    70  		meta[i].Tags = m.Tags.WithoutName()
    71  	}
    72  
    73  	return meta
    74  }
    75  
    76  // NewClampOp creates a new clamp op based on the type and arguments
    77  func NewClampOp(args []interface{}, opType string) (parser.Params, error) {
    78  	isMax := opType == ClampMaxType
    79  	if opType != ClampMinType && !isMax {
    80  		return nil, fmt.Errorf("unknown clamp type: %s", opType)
    81  	}
    82  
    83  	clampTo, err := parseClampArgs(args)
    84  	if err != nil {
    85  		return nil, err
    86  	}
    87  
    88  	fn := clampFn(isMax, clampTo)
    89  	lazyOpts := block.NewLazyOptions().
    90  		SetValueTransform(fn).
    91  		SetSeriesMetaTransform(removeName)
    92  	return lazy.NewLazyOp(opType, lazyOpts)
    93  }