Created
February 28, 2022 18:08
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a slow server useful for testing
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| package main | |
| import ( | |
| "errors" | |
| "io" | |
| "log" | |
| "net/http" | |
| "os" | |
| "strconv" | |
| "time" | |
| ) | |
| func main() { | |
| r := http.NewServeMux() | |
| r.HandleFunc("/", slow) | |
| log.Fatal(http.ListenAndServe(":9999",r)) | |
| } | |
| func slow(w http.ResponseWriter, r *http.Request) { | |
| // The slow return of this function is to take 5 minutes. | |
| // We shall return ~1MB total. and use american english dictionary for fun. | |
| f, err := os.Open("/usr/share/dict/words") | |
| if err != nil { | |
| log.Print("couldn't open /usr/share/dict/words") | |
| return | |
| } | |
| defer f.Close() | |
| t := 5 * time.Minute | |
| d := r.Form.Get("duration") | |
| if d != `` { | |
| if t2, err := time.ParseDuration(d); err == nil { | |
| t = t2 | |
| } else { | |
| log.Print("couldn't parse query parameter", d, err) | |
| } | |
| } | |
| delay := 2 * time.Second | |
| st, err := f.Stat() | |
| if err != nil { | |
| log.Print("couldn't stat /usr/share/dict/words") | |
| return | |
| } | |
| src, dst := f, w | |
| sz := int(st.Size()) | |
| chunk := sz / int(t/delay) | |
| log.Printf("/slow writing %d every %s for %s", chunk, delay, t) | |
| w.Header().Set("content-length", strconv.Itoa(sz)) | |
| buf := make([]byte, chunk) | |
| // lifted from io: | |
| for { | |
| nr, er := src.Read(buf) | |
| if nr > 0 { | |
| nw, ew := dst.Write(buf[0:nr]) | |
| if nw < 0 || nr < nw { | |
| nw = 0 | |
| if ew == nil { | |
| ew = errInvalidWrite | |
| } | |
| } | |
| time.Sleep(delay) | |
| if ew != nil { | |
| err = ew | |
| break | |
| } | |
| if nr != nw { | |
| err = io.ErrShortWrite | |
| break | |
| } | |
| } | |
| if er != nil { | |
| if er != io.EOF { | |
| err = er | |
| } | |
| break | |
| } | |
| } | |
| if err != nil { | |
| log.Printf("/slow error writing %s", err) | |
| } | |
| } | |
| // errInvalidWrite means that a write returned an impossible count. | |
| var errInvalidWrite = errors.New("invalid write result") |
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