Add a go sample

README.md

@@ -30,4 +30,9 @@ ruby server.rb
 php server.php
 ```
 
+### Go
+```sh
+go run server.go
+```
+
 And visit <http://localhost:3000/>. Try opening multiple tabs!

server.go

@@ -0,0 +1,85 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"sync"
+)
+
+type comment struct {
+	Author string `json:"author"`
+	Text   string `json:"text"`
+}
+
+const dataFile = "./_comments.json"
+
+var commentMutex = new(sync.Mutex)
+
+// Handle comments
+func handleComments(w http.ResponseWriter, r *http.Request) {
+	// Since multiple requests could come in at once, ensure we have a lock
+	// around all file operations
+	commentMutex.Lock()
+	defer commentMutex.Unlock()
+
+	// Stat the file, so we can find it's current permissions
+	fi, err := os.Stat(dataFile)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Unable to stat data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+		return
+	}
+
+	// Open the file Read/Write
+	cFile, err := os.OpenFile(dataFile, os.O_RDWR, fi.Mode())
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Unable to open data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+		return
+	}
+	defer cFile.Close() //Ensure the file is closed when we are done.
+
+	switch r.Method {
+	case "POST":
+		// Decode the JSON data
+		comments := make([]comment, 0)
+		commentsDecoder := json.NewDecoder(cFile)
+		if err := commentsDecoder.Decode(&comments); err != nil {
+			http.Error(w, fmt.Sprintf("Unable to read comments from data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+			return
+		}
+
+		// Add a new comment to the in memory slice of comments
+		comments = append(comments, comment{Author: r.FormValue("author"), Text: r.FormValue("text")})
+
+		// Truncate the file and Seek to the beginning of it
+		if err := cFile.Truncate(0); err != nil {
+			http.Error(w, fmt.Sprintf("Unable to truncate data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+			return
+		}
+		if r, err := cFile.Seek(0, 0); r != 0 && err != nil {
+			http.Error(w, fmt.Sprintf("Unable to seek to beginning of data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+			return
+		}
+
+		// Write out the json response
+		commentsEncoder := json.NewEncoder(cFile)
+		commentsEncoder.Encode(comments)
+
+	case "GET":
+		// stream the contents of the file to the response
+		io.Copy(w, cFile)
+
+	default:
+		// Don't know the method, so error
+		http.Error(w, fmt.Sprintf("Unsupported method: %s", r.Method), http.StatusMethodNotAllowed)
+	}
+}
+
+func main() {
+	http.HandleFunc("/comments.json", handleComments)
+	http.Handle("/", http.FileServer(http.Dir("./public")))
+	log.Fatal(http.ListenAndServe(":3000", nil))
+}