From f1998c321a4eec6d75b58d84aa8610971bf21979 Mon Sep 17 00:00:00 2001 From: Brian Picciano Date: Sat, 31 Jul 2021 11:35:39 -0600 Subject: move static files into static sub-dir, refactor nix a bit --- .../assets/component-oriented-design/v2/main.go | 320 +++++++++++++++++++++ .../assets/component-oriented-design/v2/main.md | 4 + 2 files changed, 324 insertions(+) create mode 100644 static/src/assets/component-oriented-design/v2/main.go create mode 100644 static/src/assets/component-oriented-design/v2/main.md (limited to 'static/src/assets/component-oriented-design/v2') diff --git a/static/src/assets/component-oriented-design/v2/main.go b/static/src/assets/component-oriented-design/v2/main.go new file mode 100644 index 0000000..fb5773c --- /dev/null +++ b/static/src/assets/component-oriented-design/v2/main.go @@ -0,0 +1,320 @@ +package main + +import ( + "encoding/json" + "errors" + "flag" + "fmt" + "io" + "io/ioutil" + "log" + "math/rand" + "net" + "net/http" + "os" + "sort" + "strconv" + "sync" + "time" +) + +// Logger describes a simple component used for printing log lines. +type Logger interface { + Printf(string, ...interface{}) +} + +//////////////////////////////////////////////////////////////////////////////// +// The scoreboard component + +// File wraps the standard os.File type. +type File interface { + io.ReadWriter + Truncate(int64) error + Seek(int64, int) (int64, error) +} + +// scoreboard loads player scores from a save file, tracks score updates, and +// periodically saves those scores back to the save file. +type scoreboard struct { + file File + scoresM map[string]int + scoresLock sync.Mutex + + pointsOnCorrect, pointsOnIncorrect int + + // this field will only be set in tests, and is used to synchronize with the + // the for-select loop in saveLoop. + saveLoopWaitCh chan struct{} +} + +// newScoreboard initializes a scoreboard using scores saved in the given File +// (which may be empty). The scoreboard will rewrite the save file with the +// latest scores everytime saveTicker is written to. +func newScoreboard(file File, saveTicker <-chan time.Time, logger Logger, pointsOnCorrect, pointsOnIncorrect int) (*scoreboard, error) { + fileBody, err := ioutil.ReadAll(file) + if err != nil { + return nil, fmt.Errorf("reading saved scored: %w", err) + } + + scoresM := map[string]int{} + if len(fileBody) > 0 { + if err := json.Unmarshal(fileBody, &scoresM); err != nil { + return nil, fmt.Errorf("decoding saved scores: %w", err) + } + } + + scoreboard := &scoreboard{ + file: file, + scoresM: scoresM, + pointsOnCorrect: pointsOnCorrect, + pointsOnIncorrect: pointsOnIncorrect, + saveLoopWaitCh: make(chan struct{}), + } + + go scoreboard.saveLoop(saveTicker, logger) + + return scoreboard, nil +} + +func (s *scoreboard) guessedCorrect(name string) int { + s.scoresLock.Lock() + defer s.scoresLock.Unlock() + + s.scoresM[name] += s.pointsOnCorrect + return s.scoresM[name] +} + +func (s *scoreboard) guessedIncorrect(name string) int { + s.scoresLock.Lock() + defer s.scoresLock.Unlock() + + s.scoresM[name] += s.pointsOnIncorrect + return s.scoresM[name] +} + +func (s *scoreboard) scores() map[string]int { + s.scoresLock.Lock() + defer s.scoresLock.Unlock() + + scoresCp := map[string]int{} + for name, score := range s.scoresM { + scoresCp[name] = score + } + + return scoresCp +} + +func (s *scoreboard) save() error { + scores := s.scores() + if _, err := s.file.Seek(0, 0); err != nil { + return fmt.Errorf("seeking to start of save file: %w", err) + } else if err := s.file.Truncate(0); err != nil { + return fmt.Errorf("truncating save file: %w", err) + } else if err := json.NewEncoder(s.file).Encode(scores); err != nil { + return fmt.Errorf("encoding scores to save file: %w", err) + } + return nil +} + +func (s *scoreboard) saveLoop(ticker <-chan time.Time, logger Logger) { + for { + select { + case <-ticker: + if err := s.save(); err != nil { + logger.Printf("error saving scoreboard to file: %v", err) + } + case <-s.saveLoopWaitCh: + // test will unblock, nothing to do here. + } + } +} + +//////////////////////////////////////////////////////////////////////////////// +// The httpHandlers component + +// Scoreboard describes the scoreboard component from the point of view of the +// httpHandler component (which only needs a subset of scoreboard's methods). +type Scoreboard interface { + guessedCorrect(name string) int + guessedIncorrect(name string) int + scores() map[string]int +} + +// RandSrc describes a randomness component which can produce random integers. +type RandSrc interface { + Int() int +} + +// httpHandlers implements the http.HandlerFuncs used by the httpServer. +type httpHandlers struct { + scoreboard Scoreboard + randSrc RandSrc + logger Logger + + mux *http.ServeMux + n int + nLock sync.Mutex +} + +func newHTTPHandlers(scoreboard Scoreboard, randSrc RandSrc, logger Logger) *httpHandlers { + n := randSrc.Int() + logger.Printf("first n is %v", n) + + httpHandlers := &httpHandlers{ + scoreboard: scoreboard, + randSrc: randSrc, + logger: logger, + mux: http.NewServeMux(), + n: n, + } + + httpHandlers.mux.HandleFunc("/guess", httpHandlers.handleGuess) + httpHandlers.mux.HandleFunc("/scores", httpHandlers.handleScores) + + return httpHandlers +} + +func (h *httpHandlers) ServeHTTP(rw http.ResponseWriter, r *http.Request) { + h.mux.ServeHTTP(rw, r) +} + +func (h *httpHandlers) handleGuess(rw http.ResponseWriter, r *http.Request) { + r.Header.Set("Content-Type", "text/plain") + + name := r.FormValue("name") + nStr := r.FormValue("n") + if name == "" || nStr == "" { + http.Error(rw, `"name" and "n" GET args are required`, http.StatusBadRequest) + return + } + + n, err := strconv.Atoi(nStr) + if err != nil { + http.Error(rw, err.Error(), http.StatusBadRequest) + return + } + + h.nLock.Lock() + defer h.nLock.Unlock() + + if h.n == n { + newScore := h.scoreboard.guessedCorrect(name) + h.n = h.randSrc.Int() + h.logger.Printf("new n is %v", h.n) + rw.WriteHeader(http.StatusOK) + fmt.Fprintf(rw, "Correct! Your score is now %d\n", newScore) + return + } + + hint := "higher" + if h.n < n { + hint = "lower" + } + + newScore := h.scoreboard.guessedIncorrect(name) + rw.WriteHeader(http.StatusBadRequest) + fmt.Fprintf(rw, "Try %s. Your score is now %d\n", hint, newScore) +} + +func (h *httpHandlers) handleScores(rw http.ResponseWriter, r *http.Request) { + r.Header.Set("Content-Type", "text/plain") + + h.nLock.Lock() + defer h.nLock.Unlock() + + type scoreTup struct { + name string + score int + } + + scores := h.scoreboard.scores() + scoresTups := make([]scoreTup, 0, len(scores)) + for name, score := range scores { + scoresTups = append(scoresTups, scoreTup{name, score}) + } + + sort.Slice(scoresTups, func(i, j int) bool { + return scoresTups[i].score > scoresTups[j].score + }) + + for _, scoresTup := range scoresTups { + fmt.Fprintf(rw, "%s: %d\n", scoresTup.name, scoresTup.score) + } +} + +//////////////////////////////////////////////////////////////////////////////// +// The httpServer component. + +type httpServer struct { + httpServer *http.Server + errCh chan error +} + +func newHTTPServer(listener net.Listener, httpHandlers *httpHandlers, logger Logger) *httpServer { + loggingHandler := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) { + ip, _, _ := net.SplitHostPort(r.RemoteAddr) + logger.Printf("HTTP request -> %s %s %s", ip, r.Method, r.URL.String()) + httpHandlers.ServeHTTP(rw, r) + }) + + server := &httpServer{ + httpServer: &http.Server{ + Handler: loggingHandler, + }, + errCh: make(chan error, 1), + } + + go func() { + err := server.httpServer.Serve(listener) + if errors.Is(err, http.ErrServerClosed) { + err = nil + } + server.errCh <- err + }() + + return server +} + +//////////////////////////////////////////////////////////////////////////////// +// main + +func main() { + saveFilePath := flag.String("save-file", "./save.json", "File used to save scores") + listenAddr := flag.String("listen-addr", ":8888", "Address to listen for HTTP requests on") + saveInterval := flag.Duration("save-interval", 5*time.Second, "How often to resave scores") + pointsOnCorrect := flag.Int("points-on-correct", 1000, "Amount to change a user's score by upon a correct score") + pointsOnIncorrect := flag.Int("points-on-incorrect", -1, "Amount to change a user's score by upon an incorrect score") + flag.Parse() + + logger := log.New(os.Stdout, "", log.LstdFlags) + + logger.Printf("opening scoreboard save file %q", *saveFilePath) + file, err := os.OpenFile(*saveFilePath, os.O_RDWR|os.O_CREATE, 0644) + if err != nil { + logger.Fatalf("failed to open file %q: %v", *saveFilePath, err) + } + + saveTicker := time.NewTicker(*saveInterval) + randSrc := rand.New(rand.NewSource(time.Now().UnixNano())) + + logger.Printf("initializing scoreboard") + scoreboard, err := newScoreboard(file, saveTicker.C, logger, *pointsOnCorrect, *pointsOnIncorrect) + if err != nil { + logger.Fatalf("failed to initialize scoreboard: %v", err) + } + + logger.Printf("listening on %q", *listenAddr) + listener, err := net.Listen("tcp", *listenAddr) + if err != nil { + logger.Fatalf("failed to listen on %q: %v", *listenAddr, err) + } + + logger.Printf("setting up HTTP handlers") + httpHandlers := newHTTPHandlers(scoreboard, randSrc, logger) + + logger.Printf("serving HTTP requests") + newHTTPServer(listener, httpHandlers, logger) + + logger.Printf("initialization done") + select {} // block forever +} diff --git a/static/src/assets/component-oriented-design/v2/main.md b/static/src/assets/component-oriented-design/v2/main.md new file mode 100644 index 0000000..37346c6 --- /dev/null +++ b/static/src/assets/component-oriented-design/v2/main.md @@ -0,0 +1,4 @@ +--- +layout: code +include: main.go +--- -- cgit v1.2.3