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54b82e944e
Implement the new APIs described in #74826. Closes #74826 Change-Id: I6a6a6964229548e9d54e7af95185011e183ee50b Reviewed-on: https://go-review.googlesource.com/c/go/+/691815 Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
69 lines
1.7 KiB
Go
69 lines
1.7 KiB
Go
// Copyright 2023 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package trace
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import (
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"fmt"
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"unsafe"
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)
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// Value is a dynamically-typed value obtained from a trace.
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type Value struct {
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kind ValueKind
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pointer unsafe.Pointer
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scalar uint64
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}
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// ValueKind is the type of a dynamically-typed value from a trace.
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type ValueKind uint8
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const (
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ValueBad ValueKind = iota
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ValueUint64
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ValueString
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)
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// Kind returns the ValueKind of the value.
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//
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// It represents the underlying structure of the value.
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//
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// New ValueKinds may be added in the future. Users of this type must be robust
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// to that possibility.
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func (v Value) Kind() ValueKind {
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return v.kind
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}
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// Uint64 returns the uint64 value for a ValueUint64.
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//
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// Panics if this Value's Kind is not ValueUint64.
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func (v Value) Uint64() uint64 {
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if v.kind != ValueUint64 {
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panic("Uint64 called on Value of a different Kind")
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}
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return v.scalar
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}
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// String returns the string value for a ValueString, and otherwise
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// a string representation of the value for other kinds of values.
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func (v Value) String() string {
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if v.kind == ValueString {
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return unsafe.String((*byte)(v.pointer), int(v.scalar))
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}
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switch v.kind {
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case ValueUint64:
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return fmt.Sprintf("Value{Uint64(%d)}", v.Uint64())
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}
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return "Value{Bad}"
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}
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// Uint64Value creates a value of kind ValueUint64.
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func Uint64Value(x uint64) Value {
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return Value{kind: ValueUint64, scalar: x}
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}
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// StringValue creates a value of kind ValueString.
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func StringValue(s string) Value {
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return Value{kind: ValueString, scalar: uint64(len(s)), pointer: unsafe.Pointer(unsafe.StringData(s))}
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}
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