dashboard: database updater for performance dashboard

This CL moves code from code.google.com/p/dvyukov-go-perf-dashboard,
which was previously reviewed.

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/97250044

dashboard/updater/updater.go

@@ -0,0 +1,128 @@
+// Copyright 2013 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 (
+	"bytes"
+	"encoding/json"
+	"encoding/xml"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+var (
+	builder   = flag.String("builder", "", "builder name")
+	key       = flag.String("key", "", "builder key")
+	gopath    = flag.String("gopath", "", "path to go repo")
+	dashboard = flag.String("dashboard", "build.golang.org", "Go Dashboard Host")
+	batch     = flag.Int("batch", 100, "upload batch size")
+)
+
+// Do not benchmark beyond this commit.
+// There is little sense in benchmarking till first commit,
+// and the benchmark won't build anyway.
+const Go1Commit = "0051c7442fed" // test/bench/shootout: update timing.log to Go 1.
+
+// HgLog represents a single Mercurial revision.
+type HgLog struct {
+	Hash   string
+	Branch string
+	Files  string
+}
+
+func main() {
+	flag.Parse()
+	logs := hgLog()
+	var hashes []string
+	ngo1 := 0
+	for i := range logs {
+		if strings.HasPrefix(logs[i].Hash, Go1Commit) {
+			break
+		}
+		if needsBenchmarking(&logs[i]) {
+			hashes = append(hashes, logs[i].Hash)
+		}
+		ngo1++
+	}
+	fmt.Printf("found %v commits, %v after Go1, %v need benchmarking\n", len(logs), ngo1, len(hashes))
+	for i := 0; i < len(hashes); i += *batch {
+		j := i + *batch
+		if j > len(hashes) {
+			j = len(hashes)
+		}
+		fmt.Printf("sending %v-%v... ", i, j)
+		res := postCommits(hashes[i:j])
+		fmt.Printf("%s\n", res)
+	}
+}
+
+func hgLog() []HgLog {
+	var out bytes.Buffer
+	cmd := exec.Command("hg", "log", "--encoding=utf-8", "--template", xmlLogTemplate)
+	cmd.Dir = *gopath
+	cmd.Stdout = &out
+	cmd.Stderr = os.Stderr
+	err := cmd.Run()
+	if err != nil {
+		fmt.Printf("failed to execute 'hg log': %v\n", err)
+		os.Exit(1)
+	}
+	var top struct{ Log []HgLog }
+	err = xml.Unmarshal([]byte("<Top>"+out.String()+"</Top>"), &top)
+	if err != nil {
+		fmt.Printf("failed to parse log: %v\n", err)
+		os.Exit(1)
+	}
+	return top.Log
+}
+
+func needsBenchmarking(log *HgLog) bool {
+	if log.Branch != "" {
+		return false
+	}
+	for _, f := range strings.Split(log.Files, " ") {
+		if (strings.HasPrefix(f, "include") || strings.HasPrefix(f, "src")) &&
+			!strings.HasSuffix(f, "_test.go") && !strings.Contains(f, "testdata") {
+			return true
+		}
+	}
+	return false
+}
+
+func postCommits(hashes []string) string {
+	args := url.Values{"builder": {*builder}, "key": {*key}}
+	cmd := fmt.Sprintf("http://%v/updatebenchmark?%v", *dashboard, args.Encode())
+	b, err := json.Marshal(hashes)
+	if err != nil {
+		return fmt.Sprintf("failed to encode request: %v\n", err)
+	}
+	r, err := http.Post(cmd, "text/json", bytes.NewReader(b))
+	if err != nil {
+		return fmt.Sprintf("failed to send http request: %v\n", err)
+	}
+	defer r.Body.Close()
+	if r.StatusCode != http.StatusOK {
+		return fmt.Sprintf("http request failed: %v\n", r.Status)
+	}
+	resp, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return fmt.Sprintf("failed to read http response: %v\n", err)
+	}
+	return string(resp)
+}
+
+const xmlLogTemplate = `
+        <Log>
+        <Hash>{node|escape}</Hash>
+        <Branch>{branches}</Branch>
+        <Files>{files}</Files>
+        </Log>
+`