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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"math"
"golang.org/x/tools/benchmark/parse"
)
// BenchCmp is a pair of benchmarks.
type BenchCmp struct {
Before *parse.Benchmark
After *parse.Benchmark
}
// Correlate correlates benchmarks from two BenchSets.
func Correlate(before, after parse.Set) (cmps []BenchCmp, warnings []string) {
cmps = make([]BenchCmp, 0, len(after))
for name, beforebb := range before {
afterbb := after[name]
if len(beforebb) != len(afterbb) {
warnings = append(warnings, fmt.Sprintf("ignoring %s: before has %d instances, after has %d", name, len(beforebb), len(afterbb)))
continue
}
for i, beforeb := range beforebb {
afterb := afterbb[i]
cmps = append(cmps, BenchCmp{beforeb, afterb})
}
}
return
}
func (c BenchCmp) Name() string { return c.Before.Name }
func (c BenchCmp) String() string { return fmt.Sprintf("<%s, %s>", c.Before, c.After) }
func (c BenchCmp) Measured(flag int) bool { return (c.Before.Measured & c.After.Measured & flag) != 0 }
func (c BenchCmp) DeltaNsPerOp() Delta { return Delta{c.Before.NsPerOp, c.After.NsPerOp} }
func (c BenchCmp) DeltaMBPerS() Delta { return Delta{c.Before.MBPerS, c.After.MBPerS} }
func (c BenchCmp) DeltaAllocedBytesPerOp() Delta {
return Delta{float64(c.Before.AllocedBytesPerOp), float64(c.After.AllocedBytesPerOp)}
}
func (c BenchCmp) DeltaAllocsPerOp() Delta {
return Delta{float64(c.Before.AllocsPerOp), float64(c.After.AllocsPerOp)}
}
// Delta is the before and after value for a benchmark measurement.
// Both must be non-negative.
type Delta struct {
Before float64
After float64
}
// mag calculates the magnitude of a change, regardless of the direction of
// the change. mag is intended for sorting and has no independent meaning.
func (d Delta) mag() float64 {
switch {
case d.Before != 0 && d.After != 0 && d.Before >= d.After:
return d.After / d.Before
case d.Before != 0 && d.After != 0 && d.Before < d.After:
return d.Before / d.After
case d.Before == 0 && d.After == 0:
return 1
default:
// 0 -> 1 or 1 -> 0
// These are significant changes and worth surfacing.
return math.Inf(1)
}
}
// Changed reports whether the benchmark quantities are different.
func (d Delta) Changed() bool { return d.Before != d.After }
// Float64 returns After / Before. If Before is 0, Float64 returns
// 1 if After is also 0, and +Inf otherwise.
func (d Delta) Float64() float64 {
switch {
case d.Before != 0:
return d.After / d.Before
case d.After == 0:
return 1
default:
return math.Inf(1)
}
}
// Percent formats a Delta as a percent change, ranging from -100% up.
func (d Delta) Percent() string {
return fmt.Sprintf("%+.2f%%", 100*d.Float64()-100)
}
// Multiple formats a Delta as a multiplier, ranging from 0.00x up.
func (d Delta) Multiple() string {
return fmt.Sprintf("%.2fx", d.Float64())
}
func (d Delta) String() string {
return fmt.Sprintf("Δ(%f, %f)", d.Before, d.After)
}
// ByParseOrder sorts BenchCmps to match the order in
// which the Before benchmarks were presented to Parse.
type ByParseOrder []BenchCmp
func (x ByParseOrder) Len() int { return len(x) }
func (x ByParseOrder) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x ByParseOrder) Less(i, j int) bool { return x[i].Before.Ord < x[j].Before.Ord }
// lessByDelta provides lexicographic ordering:
// * largest delta by magnitude
// * alphabetic by name
func lessByDelta(i, j BenchCmp, calcDelta func(BenchCmp) Delta) bool {
iDelta, jDelta := calcDelta(i).mag(), calcDelta(j).mag()
if iDelta != jDelta {
return iDelta < jDelta
}
return i.Name() < j.Name()
}
// ByDeltaNsPerOp sorts BenchCmps lexicographically by change
// in ns/op, descending, then by benchmark name.
type ByDeltaNsPerOp []BenchCmp
func (x ByDeltaNsPerOp) Len() int { return len(x) }
func (x ByDeltaNsPerOp) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x ByDeltaNsPerOp) Less(i, j int) bool { return lessByDelta(x[i], x[j], BenchCmp.DeltaNsPerOp) }
// ByDeltaMBPerS sorts BenchCmps lexicographically by change
// in MB/s, descending, then by benchmark name.
type ByDeltaMBPerS []BenchCmp
func (x ByDeltaMBPerS) Len() int { return len(x) }
func (x ByDeltaMBPerS) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x ByDeltaMBPerS) Less(i, j int) bool { return lessByDelta(x[i], x[j], BenchCmp.DeltaMBPerS) }
// ByDeltaAllocedBytesPerOp sorts BenchCmps lexicographically by change
// in B/op, descending, then by benchmark name.
type ByDeltaAllocedBytesPerOp []BenchCmp
func (x ByDeltaAllocedBytesPerOp) Len() int { return len(x) }
func (x ByDeltaAllocedBytesPerOp) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x ByDeltaAllocedBytesPerOp) Less(i, j int) bool {
return lessByDelta(x[i], x[j], BenchCmp.DeltaAllocedBytesPerOp)
}
// ByDeltaAllocsPerOp sorts BenchCmps lexicographically by change
// in allocs/op, descending, then by benchmark name.
type ByDeltaAllocsPerOp []BenchCmp
func (x ByDeltaAllocsPerOp) Len() int { return len(x) }
func (x ByDeltaAllocsPerOp) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x ByDeltaAllocsPerOp) Less(i, j int) bool {
return lessByDelta(x[i], x[j], BenchCmp.DeltaAllocsPerOp)
}