// Copyright 2023 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 version
import (
"fmt"
"io"
"internal/trace/tracev2"
)
// Version represents the version of a trace file.
type Version uint32
const (
Go111 Version = 11 // v1
Go119 Version = 19 // v1
Go121 Version = 21 // v1
Go122 Version = 22 // v2
Go123 Version = 23 // v2
Go125 Version = 25 // v2
Current = Go125
)
var versions = map[Version][]tracev2.EventSpec{
// Go 1.11–1.21 use a different parser and are only set here for the sake of
// Version.Valid.
Go111: nil,
Go119: nil,
Go121: nil,
Go122: tracev2.Specs()[:tracev2.EvUserLog+1], // All events after are Go 1.23+.
Go123: tracev2.Specs()[:tracev2.EvExperimentalBatch+1], // All events after are Go 1.25+.
Go125: tracev2.Specs(),
}
// Specs returns the set of event.Specs for this version.
func (v Version) Specs() []tracev2.EventSpec {
return versions[v]
}
// EventName returns a string name of a wire format event
// for a particular trace version.
func (v Version) EventName(typ tracev2.EventType) string {
if !v.Valid() {
return "<invalid trace version>"
}
s := v.Specs()
if len(s) == 0 {
return "<v1 trace event type>"
}
if int(typ) < len(s) && s[typ].Name != "" {
return s[typ].Name
}
return fmt.Sprintf("Invalid(%d)", typ)
}
func (v Version) Valid() bool {
_, ok := versions[v]
return ok
}
// headerFmt is the format of the header of all Go execution traces.
const headerFmt = "go 1.%d trace\x00\x00\x00"
// ReadHeader reads the version of the trace out of the trace file's
// header, whose prefix must be present in v.
func ReadHeader(r io.Reader) (Version, error) {
var v Version
_, err := fmt.Fscanf(r, headerFmt, &v)
if err != nil {
return v, fmt.Errorf("bad file format: not a Go execution trace?")
}
if !v.Valid() {
return v, fmt.Errorf("unknown or unsupported trace version go 1.%d", v)
}
return v, nil
}
// WriteHeader writes a header for a trace version v to w.
func WriteHeader(w io.Writer, v Version) (int, error) {
return fmt.Fprintf(w, headerFmt, v)
}
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