measurement.go

     1  // Copyright 2014 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package measurement export utility functions to manipulate/format performance profile sample values.
    16  package measurement
    17  
    18  import (
    19  	"fmt"
    20  	"math"
    21  	"strings"
    22  	"time"
    23  
    24  	"github.com/google/pprof/profile"
    25  )
    26  
    27  // ScaleProfiles updates the units in a set of profiles to make them
    28  // compatible. It scales the profiles to the smallest unit to preserve
    29  // data.
    30  func ScaleProfiles(profiles []*profile.Profile) error {
    31  	if len(profiles) == 0 {
    32  		return nil
    33  	}
    34  	periodTypes := make([]*profile.ValueType, 0, len(profiles))
    35  	for _, p := range profiles {
    36  		if p.PeriodType != nil {
    37  			periodTypes = append(periodTypes, p.PeriodType)
    38  		}
    39  	}
    40  	periodType, err := CommonValueType(periodTypes)
    41  	if err != nil {
    42  		return fmt.Errorf("period type: %v", err)
    43  	}
    44  
    45  	// Identify common sample types
    46  	numSampleTypes := len(profiles[0].SampleType)
    47  	for _, p := range profiles[1:] {
    48  		if numSampleTypes != len(p.SampleType) {
    49  			return fmt.Errorf("inconsistent samples type count: %d != %d", numSampleTypes, len(p.SampleType))
    50  		}
    51  	}
    52  	sampleType := make([]*profile.ValueType, numSampleTypes)
    53  	for i := 0; i < numSampleTypes; i++ {
    54  		sampleTypes := make([]*profile.ValueType, len(profiles))
    55  		for j, p := range profiles {
    56  			sampleTypes[j] = p.SampleType[i]
    57  		}
    58  		sampleType[i], err = CommonValueType(sampleTypes)
    59  		if err != nil {
    60  			return fmt.Errorf("sample types: %v", err)
    61  		}
    62  	}
    63  
    64  	for _, p := range profiles {
    65  		if p.PeriodType != nil && periodType != nil {
    66  			period, _ := Scale(p.Period, p.PeriodType.Unit, periodType.Unit)
    67  			p.Period, p.PeriodType.Unit = int64(period), periodType.Unit
    68  		}
    69  		ratios := make([]float64, len(p.SampleType))
    70  		for i, st := range p.SampleType {
    71  			if sampleType[i] == nil {
    72  				ratios[i] = 1
    73  				continue
    74  			}
    75  			ratios[i], _ = Scale(1, st.Unit, sampleType[i].Unit)
    76  			p.SampleType[i].Unit = sampleType[i].Unit
    77  		}
    78  		if err := p.ScaleN(ratios); err != nil {
    79  			return fmt.Errorf("scale: %v", err)
    80  		}
    81  	}
    82  	return nil
    83  }
    84  
    85  // CommonValueType returns the finest type from a set of compatible
    86  // types.
    87  func CommonValueType(ts []*profile.ValueType) (*profile.ValueType, error) {
    88  	if len(ts) <= 1 {
    89  		return nil, nil
    90  	}
    91  	minType := ts[0]
    92  	for _, t := range ts[1:] {
    93  		if !compatibleValueTypes(minType, t) {
    94  			return nil, fmt.Errorf("incompatible types: %v %v", *minType, *t)
    95  		}
    96  		if ratio, _ := Scale(1, t.Unit, minType.Unit); ratio < 1 {
    97  			minType = t
    98  		}
    99  	}
   100  	rcopy := *minType
   101  	return &rcopy, nil
   102  }
   103  
   104  func compatibleValueTypes(v1, v2 *profile.ValueType) bool {
   105  	if v1 == nil || v2 == nil {
   106  		return true // No grounds to disqualify.
   107  	}
   108  	// Remove trailing 's' to permit minor mismatches.
   109  	if t1, t2 := strings.TrimSuffix(v1.Type, "s"), strings.TrimSuffix(v2.Type, "s"); t1 != t2 {
   110  		return false
   111  	}
   112  
   113  	if v1.Unit == v2.Unit {
   114  		return true
   115  	}
   116  	for _, ut := range unitTypes {
   117  		if ut.sniffUnit(v1.Unit) != nil && ut.sniffUnit(v2.Unit) != nil {
   118  			return true
   119  		}
   120  	}
   121  	return false
   122  }
   123  
   124  // Scale a measurement from a unit to a different unit and returns
   125  // the scaled value and the target unit. The returned target unit
   126  // will be empty if uninteresting (could be skipped).
   127  func Scale(value int64, fromUnit, toUnit string) (float64, string) {
   128  	// Avoid infinite recursion on overflow.
   129  	if value < 0 && -value > 0 {
   130  		v, u := Scale(-value, fromUnit, toUnit)
   131  		return -v, u
   132  	}
   133  	for _, ut := range unitTypes {
   134  		if v, u, ok := ut.convertUnit(value, fromUnit, toUnit); ok {
   135  			return v, u
   136  		}
   137  	}
   138  	// Skip non-interesting units.
   139  	switch toUnit {
   140  	case "count", "sample", "unit", "minimum", "auto":
   141  		return float64(value), ""
   142  	default:
   143  		return float64(value), toUnit
   144  	}
   145  }
   146  
   147  // Label returns the label used to describe a certain measurement.
   148  func Label(value int64, unit string) string {
   149  	return ScaledLabel(value, unit, "auto")
   150  }
   151  
   152  // ScaledLabel scales the passed-in measurement (if necessary) and
   153  // returns the label used to describe a float measurement.
   154  func ScaledLabel(value int64, fromUnit, toUnit string) string {
   155  	v, u := Scale(value, fromUnit, toUnit)
   156  	sv := strings.TrimSuffix(fmt.Sprintf("%.2f", v), ".00")
   157  	if sv == "0" || sv == "-0" {
   158  		return "0"
   159  	}
   160  	return sv + u
   161  }
   162  
   163  // Percentage computes the percentage of total of a value, and encodes
   164  // it as a string. At least two digits of precision are printed.
   165  func Percentage(value, total int64) string {
   166  	var ratio float64
   167  	if total != 0 {
   168  		ratio = math.Abs(float64(value)/float64(total)) * 100
   169  	}
   170  	switch {
   171  	case math.Abs(ratio) >= 99.95 && math.Abs(ratio) <= 100.05:
   172  		return "  100%"
   173  	case math.Abs(ratio) >= 1.0:
   174  		return fmt.Sprintf("%5.2f%%", ratio)
   175  	default:
   176  		return fmt.Sprintf("%5.2g%%", ratio)
   177  	}
   178  }
   179  
   180  // unit includes a list of aliases representing a specific unit and a factor
   181  // which one can multiple a value in the specified unit by to get the value
   182  // in terms of the base unit.
   183  type unit struct {
   184  	canonicalName string
   185  	aliases       []string
   186  	factor        float64
   187  }
   188  
   189  // unitType includes a list of units that are within the same category (i.e.
   190  // memory or time units) and a default unit to use for this type of unit.
   191  type unitType struct {
   192  	defaultUnit unit
   193  	units       []unit
   194  }
   195  
   196  // findByAlias returns the unit associated with the specified alias. It returns
   197  // nil if the unit with such alias is not found.
   198  func (ut unitType) findByAlias(alias string) *unit {
   199  	for _, u := range ut.units {
   200  		for _, a := range u.aliases {
   201  			if alias == a {
   202  				return &u
   203  			}
   204  		}
   205  	}
   206  	return nil
   207  }
   208  
   209  // sniffUnit simpifies the input alias and returns the unit associated with the
   210  // specified alias. It returns nil if the unit with such alias is not found.
   211  func (ut unitType) sniffUnit(unit string) *unit {
   212  	unit = strings.ToLower(unit)
   213  	if len(unit) > 2 {
   214  		unit = strings.TrimSuffix(unit, "s")
   215  	}
   216  	return ut.findByAlias(unit)
   217  }
   218  
   219  // autoScale takes in the value with units of the base unit and returns
   220  // that value scaled to a reasonable unit if a reasonable unit is
   221  // found.
   222  func (ut unitType) autoScale(value float64) (float64, string, bool) {
   223  	var f float64
   224  	var unit string
   225  	for _, u := range ut.units {
   226  		if u.factor >= f && (value/u.factor) >= 1.0 {
   227  			f = u.factor
   228  			unit = u.canonicalName
   229  		}
   230  	}
   231  	if f == 0 {
   232  		return 0, "", false
   233  	}
   234  	return value / f, unit, true
   235  }
   236  
   237  // convertUnit converts a value from the fromUnit to the toUnit, autoscaling
   238  // the value if the toUnit is "minimum" or "auto". If the fromUnit is not
   239  // included in the unitType, then a false boolean will be returned. If the
   240  // toUnit is not in the unitType, the value will be returned in terms of the
   241  // default unitType.
   242  func (ut unitType) convertUnit(value int64, fromUnitStr, toUnitStr string) (float64, string, bool) {
   243  	fromUnit := ut.sniffUnit(fromUnitStr)
   244  	if fromUnit == nil {
   245  		return 0, "", false
   246  	}
   247  	v := float64(value) * fromUnit.factor
   248  	if toUnitStr == "minimum" || toUnitStr == "auto" {
   249  		if v, u, ok := ut.autoScale(v); ok {
   250  			return v, u, true
   251  		}
   252  		return v / ut.defaultUnit.factor, ut.defaultUnit.canonicalName, true
   253  	}
   254  	toUnit := ut.sniffUnit(toUnitStr)
   255  	if toUnit == nil {
   256  		return v / ut.defaultUnit.factor, ut.defaultUnit.canonicalName, true
   257  	}
   258  	return v / toUnit.factor, toUnit.canonicalName, true
   259  }
   260  
   261  var unitTypes = []unitType{{
   262  	units: []unit{
   263  		{"B", []string{"b", "byte"}, 1},
   264  		{"kB", []string{"kb", "kbyte", "kilobyte"}, float64(1 << 10)},
   265  		{"MB", []string{"mb", "mbyte", "megabyte"}, float64(1 << 20)},
   266  		{"GB", []string{"gb", "gbyte", "gigabyte"}, float64(1 << 30)},
   267  		{"TB", []string{"tb", "tbyte", "terabyte"}, float64(1 << 40)},
   268  		{"PB", []string{"pb", "pbyte", "petabyte"}, float64(1 << 50)},
   269  	},
   270  	defaultUnit: unit{"B", []string{"b", "byte"}, 1},
   271  }, {
   272  	units: []unit{
   273  		{"ns", []string{"ns", "nanosecond"}, float64(time.Nanosecond)},
   274  		{"us", []string{"μs", "us", "microsecond"}, float64(time.Microsecond)},
   275  		{"ms", []string{"ms", "millisecond"}, float64(time.Millisecond)},
   276  		{"s", []string{"s", "sec", "second"}, float64(time.Second)},
   277  		{"hrs", []string{"hour", "hr"}, float64(time.Hour)},
   278  	},
   279  	defaultUnit: unit{"s", []string{}, float64(time.Second)},
   280  }, {
   281  	units: []unit{
   282  		{"n*GCU", []string{"nanogcu"}, 1e-9},
   283  		{"u*GCU", []string{"microgcu"}, 1e-6},
   284  		{"m*GCU", []string{"milligcu"}, 1e-3},
   285  		{"GCU", []string{"gcu"}, 1},
   286  		{"k*GCU", []string{"kilogcu"}, 1e3},
   287  		{"M*GCU", []string{"megagcu"}, 1e6},
   288  		{"G*GCU", []string{"gigagcu"}, 1e9},
   289  		{"T*GCU", []string{"teragcu"}, 1e12},
   290  		{"P*GCU", []string{"petagcu"}, 1e15},
   291  	},
   292  	defaultUnit: unit{"GCU", []string{}, 1.0},
   293  }}
   294
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