godoc: minor tweaks for app-engine use

- read search index files in groutine to avoid
  start-up failure on app engine because reading
  the files takes too long
- permit usage of search index files and indexer
- minor cosmetic cleanups

R=dsymonds
CC=golang-dev
https://golang.org/cl/4952050

src/cmd/godoc/appconfig.go

@@ -17,9 +17,11 @@ const (
 	// in the .zip file.
 	zipGoroot = "/home/user/go"
 
-	// indexFilenames is a glob pattern specifying
-	// files containing the search index served by
-	// godoc. The files are concatenated in sorted
+	// If indexFilenames != "", the search index is
+	// initialized with the index stored in these
+	// files (otherwise it will be built at run-time,
+	// eventually). indexFilenames is a glob pattern;
+	// the specified files are concatenated in sorted
 	// order (by filename).
 	// app-engine limit: file sizes must be <= 10MB;
 	// use "split -b8m indexfile index.split." to get

src/cmd/godoc/appinit.go

@@ -88,9 +88,7 @@ func init() {
 
 	// initialize search index
 	if *indexEnabled {
-		if err := initIndex(); err != nil {
-			log.Fatalf("error initializing index: %s", err)
-		}
+		go indexer()
 	}
 
 	log.Println("godoc initialization complete")

src/cmd/godoc/godoc.go

@@ -1065,12 +1065,8 @@ func lookup(query string) (result SearchResult) {
 	if *indexEnabled {
 		if _, ts := fsModified.get(); timestamp < ts {
 			// The index is older than the latest file system change under godoc's observation.
-			if *indexFiles != "" {
-				result.Alert = "Index not automatically updated: result may be inaccurate"
-			} else {
 			result.Alert = "Indexing in progress: result may be inaccurate"
 		}
-		}
 	} else {
 		result.Alert = "Search index disabled: no results available"
 	}
@@ -1145,6 +1141,29 @@ func fsDirnames() <-chan string {
 	return c
 }
 
+func readIndex(filenames string) os.Error {
+	matches, err := filepath.Glob(filenames)
+	if err != nil {
+		return err
+	}
+	sort.Strings(matches) // make sure files are in the right order
+	files := make([]io.Reader, 0, len(matches))
+	for _, filename := range matches {
+		f, err := os.Open(filename)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		files = append(files, f)
+	}
+	x := new(Index)
+	if err := x.Read(io.MultiReader(files...)); err != nil {
+		return err
+	}
+	searchIndex.set(x)
+	return nil
+}
+
 func updateIndex() {
 	if *verbose {
 		log.Printf("updating index...")
@@ -1165,6 +1184,14 @@ func updateIndex() {
 }
 
 func indexer() {
+	// initialize the index from disk if possible
+	if *indexFiles != "" {
+		if err := readIndex(*indexFiles); err != nil {
+			log.Printf("error reading index: %s", err)
+		}
+	}
+
+	// repeatedly update the index when it goes out of date
 	for {
 		if !indexUpToDate() {
 			// index possibly out of date - make a new one
@@ -1178,33 +1205,3 @@ func indexer() {
 		time.Sleep(delay)
 	}
 }
-
-func initIndex() os.Error {
-	if *indexFiles == "" {
-		// run periodic indexer
-		go indexer()
-		return nil
-	}
-
-	// get search index from files
-	matches, err := filepath.Glob(*indexFiles)
-	if err != nil {
-		return err
-	}
-	sort.Strings(matches) // make sure files are in the right order
-	files := make([]io.Reader, 0, len(matches))
-	for _, filename := range matches {
-		f, err := os.Open(filename)
-		if err != nil {
-			return err
-		}
-		defer f.Close()
-		files = append(files, f)
-	}
-	x := new(Index)
-	if err := x.Read(io.MultiReader(files...)); err != nil {
-		return err
-	}
-	searchIndex.set(x)
-	return nil
-}

src/cmd/godoc/main.go

@@ -248,6 +248,7 @@ func main() {
 		if err != nil {
 			log.Fatalf("%s: %s\n", *zipfile, err)
 		}
+		defer rc.Close()                  // be nice (e.g., -writeIndex mode)
 		*goroot = path.Join("/", *goroot) // fsHttp paths are relative to '/'
 		fs = NewZipFS(rc)
 		fsHttp = NewHttpZipFS(rc, *goroot)
@@ -262,8 +263,9 @@ func main() {
 	}
 
 	if *writeIndex {
+		// Write search index and exit.
 		if *indexFiles == "" {
-			log.Fatal("no index files specified")
+			log.Fatal("no index file specified")
 		}
 
 		log.Println("initialize file systems")
@@ -342,9 +344,7 @@ func main() {
 
 		// Initialize search index.
 		if *indexEnabled {
-			if err := initIndex(); err != nil {
-				log.Fatalf("error initializing index: %s", err)
-			}
+			go indexer()
 		}
 
 		// Start http server.