gofmt: add profiling flag

R=gri
CC=golang-dev
https://golang.org/cl/4295062

diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index a688c8184c43ef289add02c3c14fadd1bec4f8ac..1e85581571db83ebe9264e34c4a663fa0ac1a6ca 100644 (file)
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -16,6 +16,7 @@ import (
        "io/ioutil"
        "os"
        "path/filepath"
+       "runtime/pprof"
        "strings"
 )
 
@@ -32,6 +33,9 @@ var (
        tabWidth  = flag.Int("tabwidth", 8, "tab width")
        tabIndent = flag.Bool("tabindent", true, "indent with tabs independent of -spaces")
        useSpaces = flag.Bool("spaces", true, "align with spaces instead of tabs")
+
+       // debugging
+       cpuprofile = flag.String("cpuprofile", "", "write cpu profile to this file")
 )
 
 
@@ -172,11 +176,33 @@ func walkDir(path string) {
 
 
 func main() {
+       // call gofmtMain in a separate function
+       // so that it can use defer and have them
+       // run before the exit.
+       gofmtMain()
+       os.Exit(exitCode)
+}
+
+
+func gofmtMain() {
        flag.Usage = usage
        flag.Parse()
        if *tabWidth < 0 {
                fmt.Fprintf(os.Stderr, "negative tabwidth %d\n", *tabWidth)
-               os.Exit(2)
+               exitCode = 2
+               return
+       }
+
+       if *cpuprofile != "" {
+               f, err := os.Open(*cpuprofile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0666)
+               if err != nil {
+                       fmt.Fprintf(os.Stderr, "creating cpu profile: %s\n", err)
+                       exitCode = 2
+                       return
+               }
+               defer f.Close()
+               pprof.StartCPUProfile(f)
+               defer pprof.StopCPUProfile()
        }
 
        initParserMode()
@@ -202,6 +228,4 @@ func main() {
                        walkDir(path)
                }
        }
-
-       os.Exit(exitCode)
 }