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// Copyright 2022 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.
// Benchmark for accessing Value values.
package slog
import (
"testing"
"time"
)
// The "As" form is the slowest.
// The switch-panic and visitor times are almost the same.
// BenchmarkDispatch/switch-checked-8 8669427 137.7 ns/op
// BenchmarkDispatch/As-8 8212087 145.3 ns/op
// BenchmarkDispatch/Visit-8 8926146 135.3 ns/op
func BenchmarkDispatch(b *testing.B) {
vs := []Value{
Int64Value(32768),
Uint64Value(0xfacecafe),
StringValue("anything"),
BoolValue(true),
Float64Value(1.2345),
DurationValue(time.Second),
AnyValue(b),
}
var (
ii int64
s string
bb bool
u uint64
d time.Duration
f float64
a any
)
b.Run("switch-checked", func(b *testing.B) {
for i := 0; i < b.N; i++ {
for _, v := range vs {
switch v.Kind() {
case KindString:
s = v.String()
case KindInt64:
ii = v.Int64()
case KindUint64:
u = v.Uint64()
case KindFloat64:
f = v.Float64()
case KindBool:
bb = v.Bool()
case KindDuration:
d = v.Duration()
case KindAny:
a = v.Any()
default:
panic("bad kind")
}
}
}
_ = ii
_ = s
_ = bb
_ = u
_ = d
_ = f
_ = a
})
b.Run("As", func(b *testing.B) {
for i := 0; i < b.N; i++ {
for _, kv := range vs {
if v, ok := kv.AsString(); ok {
s = v
} else if v, ok := kv.AsInt64(); ok {
ii = v
} else if v, ok := kv.AsUint64(); ok {
u = v
} else if v, ok := kv.AsFloat64(); ok {
f = v
} else if v, ok := kv.AsBool(); ok {
bb = v
} else if v, ok := kv.AsDuration(); ok {
d = v
} else if v, ok := kv.AsAny(); ok {
a = v
} else {
panic("bad kind")
}
}
}
_ = ii
_ = s
_ = bb
_ = u
_ = d
_ = f
_ = a
})
b.Run("Visit", func(b *testing.B) {
v := &setVisitor{}
b.ResetTimer()
for i := 0; i < b.N; i++ {
for _, kv := range vs {
kv.Visit(v)
}
}
})
}
type setVisitor struct {
i int64
s string
b bool
u uint64
d time.Duration
f float64
a any
}
func (v *setVisitor) String(s string) { v.s = s }
func (v *setVisitor) Int64(i int64) { v.i = i }
func (v *setVisitor) Uint64(x uint64) { v.u = x }
func (v *setVisitor) Float64(x float64) { v.f = x }
func (v *setVisitor) Bool(x bool) { v.b = x }
func (v *setVisitor) Duration(x time.Duration) { v.d = x }
func (v *setVisitor) Any(x any) { v.a = x }
// When dispatching on all types, the "As" functions are slightly slower
// than switching on the kind and then calling a function that checks
// the kind again. See BenchmarkDispatch above.
func (a Value) AsString() (string, bool) {
if a.Kind() == KindString {
return a.str(), true
}
return "", false
}
func (a Value) AsInt64() (int64, bool) {
if a.Kind() == KindInt64 {
return int64(a.num), true
}
return 0, false
}
func (a Value) AsUint64() (uint64, bool) {
if a.Kind() == KindUint64 {
return a.num, true
}
return 0, false
}
func (a Value) AsFloat64() (float64, bool) {
if a.Kind() == KindFloat64 {
return a.float(), true
}
return 0, false
}
func (a Value) AsBool() (bool, bool) {
if a.Kind() == KindBool {
return a.bool(), true
}
return false, false
}
func (a Value) AsDuration() (time.Duration, bool) {
if a.Kind() == KindDuration {
return a.duration(), true
}
return 0, false
}
func (a Value) AsAny() (any, bool) {
if a.Kind() == KindAny {
return a.any, true
}
return nil, false
}
// Problem: adding a type means adding a method, which is a breaking change.
// Using an unexported method to force embedding will make programs compile,
// But they will panic at runtime when we call the new method.
type Visitor interface {
String(string)
Int64(int64)
Uint64(uint64)
Float64(float64)
Bool(bool)
Duration(time.Duration)
Any(any)
}
func (a Value) Visit(v Visitor) {
switch a.Kind() {
case KindString:
v.String(a.str())
case KindInt64:
v.Int64(int64(a.num))
case KindUint64:
v.Uint64(a.num)
case KindBool:
v.Bool(a.bool())
case KindFloat64:
v.Float64(a.float())
case KindDuration:
v.Duration(a.duration())
case KindAny:
v.Any(a.any)
default:
panic("bad kind")
}
}