136 lines
2.7 KiB
Go
136 lines
2.7 KiB
Go
// Visualize debug information from hamnet70.
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//
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// This program is a HTTP server which reads JSON messages (one per line) from
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// a FIFO filled by hamnet70 and passes them to the browser via WebSocket.
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// Concurrent browser sessions and reconnects are supported. This binary is
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// standalone and can be used without the static/ directory.
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package main
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import (
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"bufio"
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"embed"
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"io/fs"
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"log"
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"net/http"
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"os"
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"sync"
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"time"
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"golang.org/x/net/websocket"
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)
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//go:embed static/*
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var static embed.FS
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func main() {
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if len(os.Args) != 2 && len(os.Args) != 3 {
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log.SetFlags(0)
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log.Fatalf("usage: %s <fifo> [<json-dup-prefix>]", os.Args[0])
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}
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var mutex sync.Mutex
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listeners := make(map[*chan string]struct{})
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go func() {
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for {
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path := os.Args[1]
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var dupPath string
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if len(os.Args) == 3 {
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dupPath = os.Args[2] + "." + time.Now().Format(time.RFC3339)
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}
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fh, err := os.Open(path)
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if err != nil {
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log.Fatal(err)
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}
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var dupFh *os.File
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if dupPath != "" {
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dupFh, err = os.Create(dupPath)
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if err != nil {
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log.Fatal(err)
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}
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}
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r := bufio.NewReader(fh)
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for {
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line, err := r.ReadString('\n')
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if err != nil {
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log.Printf("read %q: %v", path, err)
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break
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}
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// Duplicate JSON input to a file so it can be replayed later
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// if necessary
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if dupFh != nil {
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_, err = dupFh.WriteString(line)
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if err != nil {
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log.Fatalf("write %q: %v", dupPath, err)
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}
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}
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// Send to all listeners
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mutex.Lock()
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for x := range listeners {
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*x <- line
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}
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mutex.Unlock()
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}
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err = fh.Close()
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if err != nil {
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log.Fatalf("close %q: %v", path, err)
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}
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if dupFh != nil {
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err = dupFh.Close()
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if err != nil {
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log.Fatalf("close %q: %v", dupPath, err)
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}
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}
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}
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}()
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// Use existing "./static/" directory for quick changes
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var staticFS http.FileSystem
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_, err := os.Stat("static")
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if err == nil {
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staticFS = http.Dir("static")
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} else {
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x, err := fs.Sub(static, "static")
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if err != nil {
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log.Fatal(err)
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}
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staticFS = http.FS(x)
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}
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http.Handle("/", http.FileServer(staticFS))
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http.Handle("/events", websocket.Handler(func(conn *websocket.Conn) {
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// Register new listener for this connection
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ch := make(chan string, 512) // buffer up to x number of messages
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mutex.Lock()
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listeners[&ch] = struct{}{}
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mutex.Unlock()
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defer func() {
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mutex.Lock()
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delete(listeners, &ch)
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mutex.Unlock()
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}()
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for {
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x := <-ch
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err := websocket.Message.Send(conn, x)
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if err != nil {
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log.Printf("Websocket error: %v", err)
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break
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}
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}
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}))
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err = http.ListenAndServe("localhost:8080", nil)
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if err != nil {
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log.Fatal(err)
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}
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}
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// vi: set noet ts=4 sw=4 sts=4:
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