Remake exvar package to be more Go-ish.

It now exports a Var interface (anyone can export their own custom var types now), so users need to create and manage their own vars and mark them as exportable via the Publish function. They are exposed via /debug/vars.

R=r,rsc
APPROVED=r
DELTA=605  (314 added, 186 deleted, 105 changed)
OCL=28143
CL=28239

1 files changed, 16 insertions, 4 deletions

diff --git a/src/lib/http/triv.go b/src/lib/http/triv.go
index 7678b3fff8..c452e2f5c3 100644
--- a/src/lib/http/triv.go
+++ b/src/lib/http/triv.go
@@ -17,8 +17,9 @@ import (
 
 
 // hello world, the web server
+var helloRequests = exvar.NewInt("hello-requests");
 func HelloServer(c *http.Conn, req *http.Request) {
-	exvar.IncrementInt("hello-requests", 1);
+	helloRequests.Add(1);
 	io.WriteString(c, "hello, world!\n");
 }
 
@@ -27,16 +28,23 @@ type Counter struct {
 	n int;
 }
 
+// This makes Counter satisfy the exvar.Var interface, so we can export
+// it directly.
+func (ctr *Counter) String() string {
+	return fmt.Sprintf("%d", ctr.n)
+}
+
 func (ctr *Counter) ServeHTTP(c *http.Conn, req *http.Request) {
-	exvar.IncrementInt("counter-requests", 1);
 	fmt.Fprintf(c, "counter = %d\n", ctr.n);
 	ctr.n++;
 }
 
 // simple file server
 var webroot = flag.String("root", "/home/rsc", "web root directory")
+var pathVar = exvar.NewMap("file-requests");
 func FileServer(c *http.Conn, req *http.Request) {
 	c.SetHeader("content-type", "text/plain; charset=utf-8");
+	pathVar.Add(req.Url.Path, 1);
 	path := *webroot + req.Url.Path;	// TODO: insecure: use os.CleanName
 	f, err := os.Open(path, os.O_RDONLY, 0);
 	if err != nil {
@@ -89,13 +97,17 @@ func (ch Chan) ServeHTTP(c *http.Conn, req *http.Request) {
 
 func main() {
 	flag.Parse();
-	http.Handle("/counter", new(Counter));
+
+	// The counter is published as a variable directly.
+	ctr := new(Counter);
+	http.Handle("/counter", ctr);
+	exvar.Publish("counter", ctr);
+
 	http.Handle("/go/", http.HandlerFunc(FileServer));
 	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("/exvar", http.HandlerFunc(exvar.ExvarHandler));
 	err := http.ListenAndServe(":12345", nil);
 	if err != nil {
 		panic("ListenAndServe: ", err.String())