internal/trace/v2: add gotraceeventstats utility

Change-Id: Ibf83d74a76edf2fe2896fa1e7f93ab1296fc5d75
Reviewed-on: https://go-review.googlesource.com/c/go/+/583378
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>

diff --git a/src/internal/trace/v2/testdata/cmd/gotraceeventstats/main.go b/src/internal/trace/v2/testdata/cmd/gotraceeventstats/main.go
new file mode 100644 (file)
index 0000000..ad06af6
--- /dev/null
+++ b/src/internal/trace/v2/testdata/cmd/gotraceeventstats/main.go
@@ -0,0 +1,136 @@
+// 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 main
+
+import (
+       "cmp"
+       "encoding/binary"
+       "flag"
+       "fmt"
+       "io"
+       "log"
+       "os"
+       "slices"
+       "text/tabwriter"
+
+       "internal/trace/v2/event"
+       "internal/trace/v2/raw"
+)
+
+func init() {
+       flag.Usage = func() {
+               fmt.Fprintf(flag.CommandLine.Output(), "Usage: %s [mode]\n", os.Args[0])
+               fmt.Fprintf(flag.CommandLine.Output(), "\n")
+               fmt.Fprintf(flag.CommandLine.Output(), "Accepts a trace at stdin.\n")
+               fmt.Fprintf(flag.CommandLine.Output(), "\n")
+               fmt.Fprintf(flag.CommandLine.Output(), "Supported modes:")
+               fmt.Fprintf(flag.CommandLine.Output(), "\n")
+               fmt.Fprintf(flag.CommandLine.Output(), "* size  - dumps size stats\n")
+               fmt.Fprintf(flag.CommandLine.Output(), "\n")
+               flag.PrintDefaults()
+       }
+       log.SetFlags(0)
+}
+
+func main() {
+       log.SetPrefix("")
+       flag.Parse()
+
+       if flag.NArg() != 1 {
+               log.Print("missing mode argument")
+               flag.Usage()
+               os.Exit(1)
+       }
+       var err error
+       switch mode := flag.Arg(0); mode {
+       case "size":
+               err = printSizeStats(os.Stdin)
+       default:
+               log.Printf("unknown mode %q", mode)
+               flag.Usage()
+               os.Exit(1)
+       }
+       if err != nil {
+               log.Fatalf("error: %v", err)
+               os.Exit(1)
+       }
+}
+
+func printSizeStats(r io.Reader) error {
+       cr := countingReader{Reader: r}
+       tr, err := raw.NewReader(&cr)
+       if err != nil {
+               return err
+       }
+       type eventStats struct {
+               typ   event.Type
+               count int
+               bytes int
+       }
+       var stats [256]eventStats
+       for i := range stats {
+               stats[i].typ = event.Type(i)
+       }
+       eventsRead := 0
+       for {
+               e, err := tr.ReadEvent()
+               if err == io.EOF {
+                       break
+               }
+               if err != nil {
+                       return err
+               }
+               s := &stats[e.Ev]
+               s.count++
+               s.bytes += encodedSize(&e)
+               eventsRead++
+       }
+       slices.SortFunc(stats[:], func(a, b eventStats) int {
+               return cmp.Compare(b.bytes, a.bytes)
+       })
+       specs := tr.Version().Specs()
+       w := tabwriter.NewWriter(os.Stdout, 3, 8, 2, ' ', 0)
+       fmt.Fprintf(w, "Event\tBytes\t%%\tCount\t%%\n")
+       fmt.Fprintf(w, "-\t-\t-\t-\t-\n")
+       for i := range stats {
+               stat := &stats[i]
+               name := ""
+               if int(stat.typ) >= len(specs) {
+                       name = fmt.Sprintf("<unknown (%d)>", stat.typ)
+               } else {
+                       name = specs[stat.typ].Name
+               }
+               bytesPct := float64(stat.bytes) / float64(cr.bytesRead) * 100
+               countPct := float64(stat.count) / float64(eventsRead) * 100
+               fmt.Fprintf(w, "%s\t%d\t%.2f%%\t%d\t%.2f%%\n", name, stat.bytes, bytesPct, stat.count, countPct)
+       }
+       w.Flush()
+       return nil
+}
+
+func encodedSize(e *raw.Event) int {
+       size := 1
+       var buf [binary.MaxVarintLen64]byte
+       for _, arg := range e.Args {
+               size += binary.PutUvarint(buf[:], arg)
+       }
+       spec := e.Version.Specs()[e.Ev]
+       if spec.HasData {
+               size += binary.PutUvarint(buf[:], uint64(len(e.Data)))
+               size += len(e.Data)
+       }
+       return size
+}
+
+type countingReader struct {
+       io.Reader
+       bytesRead int
+}
+
+func (r *countingReader) Read(b []byte) (int, error) {
+       n, err := r.Reader.Read(b)
+       r.bytesRead += n
+       return n, err
+}