add execution time to backend for final question

Author: usrbinsam

docker/main.go

@@ -20,73 +20,48 @@ import (
 var DEBUG = os.Getenv("DEBUG") == "1"
 
 type Response struct {
-Output string `json:"output"`
-Error string `json:"error"`
+Output string `json:"output"`
+Error string `json:"error"`
+ExecutionTime int64 `json:"time"`
+Code string `json:"code"`
 }
 
-/**
- * Pass STDIN to the Python interpreter
- */
-func execPython(timeout time.Duration, code *string) (stdout string, stderr string) {
-
-debug("applying seccomp filter for Python")
-
-ApplySyscallRestrictions()
-
-debug("building command context with %v timeout", timeout)
-ctx, cancel := context.WithTimeout(context.Background(), timeout)
-defer cancel()
-
-cmd := exec.CommandContext(ctx, "/usr/bin/python3")
-cmd.Stdin = strings.NewReader(*code)
-
-var errBuffer bytes.Buffer
-cmd.Stderr = &errBuffer
-
-debug("executing command ...")
-out, _ := cmd.Output()
-
-if ctx.Err() == context.DeadlineExceeded {
-debug("command timed out")
-stderr = "command timed out"
-return
-}
-
-stdout = string(out)
-stderr = errBuffer.String()
-
-return
+func (r Response) toJSON() string {
+data, _ := json.Marshal(r)
+return string(data)
 }
 
-func execNode(timeout time.Duration, code *string) (stdout string, stderr string) {
-debug("applying seccomp filter for NodeJS")
-
+func execSandbox(interpreter string, timeout time.Duration, code *string) *Response {
+res := Response{}
 ApplySyscallRestrictions()
 
 debug("building command context with %v timeout", timeout)
 ctx, cancel := context.WithTimeout(context.Background(), timeout)
 defer cancel()
 
-cmd := exec.CommandContext(ctx, "node")
+cmd := exec.CommandContext(ctx, interpreter)
 cmd.Stdin = strings.NewReader(*code)
-debug("stdin: %s", *code)
+res.Code = *code
 
 var errBuffer bytes.Buffer
 cmd.Stderr = &errBuffer
 
 debug("executing command ...")
+start := time.Now()
 out, _ := cmd.Output()
+elapsed := time.Since(start)
+
+res.ExecutionTime = elapsed.Milliseconds()
 
 if ctx.Err() == context.DeadlineExceeded {
 debug("command timed out")
-stderr = "command timed out"
-return
+res.Error = "command timed out"
 }
 
-stdout = string(out)
-stderr = errBuffer.String()
+res.Output = string(out)
+res.Error = errBuffer.String()
 
-return
+return &res
 }
 
 func debug(msg string, args ...interface{}) {
@@ -127,22 +102,25 @@ func main() {
 }
 
 var (
-stdout string
-stderr string
+interpreter string
+response Response
 )
 
-if language == "python" || language == "py" {
-stdout, stderr = execPython(duration, &data)
-} else if language == "javascript" || language == "js" || language == "node" {
-stdout, stderr = execNode(duration, &data)
-}
-
-r, e := json.Marshal(Response{stdout, stderr})
-
-if e != nil {
-fmt.Printf(`{"output": "", "error": "unexpected error code output to JSON!"}`)
+switch language {
+case "python":
+case "py":
+interpreter = "/usr/bin/python3"
+case "javascript":
+case "js":
+case "node":
+interpreter = "node"
+default:
+response.Error = fmt.Sprintf("unrecognized language %q", language)
+fmt.Print(response.toJSON())
 return
 }
 
-fmt.Print(string(r))
+response = *execSandbox(interpreter, duration, &data)
+
+fmt.Print(response.toJSON())
 }