net/http: couple more triv.go modernizations

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5834049

diff --git a/src/pkg/net/http/triv.go b/src/pkg/net/http/triv.go
index adf5a00be146a6d0f4bd8ffc3ad0fd9a2d14e765..232d6508906328a53855a995cd63db02bcc3f477 100644 (file)
--- a/src/pkg/net/http/triv.go
+++ b/src/pkg/net/http/triv.go
@@ -17,6 +17,7 @@ import (
        "os"
        "os/exec"
        "strconv"
+       "sync"
 )
 
 // hello world, the web server
@@ -29,14 +30,21 @@ func HelloServer(w http.ResponseWriter, req *http.Request) {
 
 // Simple counter server. POSTing to it will set the value.
 type Counter struct {
-       n int
+       mu sync.Mutex // protects n
+       n  int
 }
 
 // This makes Counter satisfy the expvar.Var interface, so we can export
 // it directly.
-func (ctr *Counter) String() string { return fmt.Sprintf("%d", ctr.n) }
+func (ctr *Counter) String() string {
+       ctr.mu.Lock()
+       defer ctr.mu.Unlock()
+       return fmt.Sprintf("%d", ctr.n)
+}
 
 func (ctr *Counter) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+       ctr.mu.Lock()
+       defer ctr.mu.Unlock()
        switch req.Method {
        case "GET":
                ctr.n++
@@ -110,23 +118,22 @@ func Logger(w http.ResponseWriter, req *http.Request) {
        http.Error(w, "oops", 404)
 }
 
-var webroot = flag.String("root", "/home/rsc", "web root directory")
+var webroot = flag.String("root", os.Getenv("HOME"), "web root directory")
 
 func main() {
        flag.Parse()
 
        // The counter is published as a variable directly.
        ctr := new(Counter)
-       http.Handle("/counter", ctr)
        expvar.Publish("counter", ctr)
-
+       http.Handle("/counter", ctr)
        http.Handle("/", http.HandlerFunc(Logger))
        http.Handle("/go/", http.StripPrefix("/go/", http.FileServer(http.Dir(*webroot))))
-       http.Handle("/flags", http.HandlerFunc(FlagServer))
-       http.Handle("/args", http.HandlerFunc(ArgServer))
-       http.Handle("/go/hello", http.HandlerFunc(HelloServer))
        http.Handle("/chan", ChanCreate())
-       http.Handle("/date", http.HandlerFunc(DateServer))
+       http.HandleFunc("/flags", FlagServer)
+       http.HandleFunc("/args", ArgServer)
+       http.HandleFunc("/go/hello", HelloServer)
+       http.HandleFunc("/date", DateServer)
        err := http.ListenAndServe(":12345", nil)
        if err != nil {
                log.Panicln("ListenAndServe:", err)