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server.go
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server.go
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// A lot of this was adapted from https://gist.github.com/ismasan/3fb75381cd2deb6bfa9c
// Great big thanks to Ismael Celis for that work.
package server
import (
"embed"
"encoding/json"
"fmt"
"log"
"net/http"
"time"
"github.com/demmydemon/httptail/config"
)
//go:embed static/*
var static embed.FS
type TailServer struct {
addClient chan chan TailMessage
removeClient chan chan TailMessage
clients map[chan TailMessage]time.Time
Messaging chan TailMessage
useEmbedded bool
buffer MessageBuffer
}
func NewServer(cfg config.Configuration) (server *TailServer) {
server = &TailServer{
addClient: make(chan chan TailMessage),
removeClient: make(chan chan TailMessage),
clients: make(map[chan TailMessage]time.Time),
Messaging: make(chan TailMessage, 1),
useEmbedded: cfg.UseEmbedded,
buffer: NewMessageBuffer(cfg.BufferLength),
}
go server.dispatch()
go server.listen(cfg.Port)
return
}
func (server *TailServer) listen(port int) {
log.Fatal("Fatal error in HTTP server: ", http.ListenAndServe(fmt.Sprintf(":%d", port), server))
}
func (server *TailServer) dispatch() {
for {
select {
case client := <-server.addClient:
server.clients[client] = time.Now()
log.Printf("Addded client, %d now connected", len(server.clients))
case client := <-server.removeClient:
delete(server.clients, client)
log.Printf("Removed client, %d now connected", len(server.clients))
case message := <-server.Messaging:
server.buffer.Add(message)
for clientChannel := range server.clients {
clientChannel <- message
}
}
}
}
func (server *TailServer) ServeEvents(rw http.ResponseWriter, req *http.Request) {
flusher, ok := rw.(http.Flusher)
if !ok {
http.Error(rw, "Sorry, I can't stream events to you.", http.StatusInternalServerError)
return
}
log.Printf("--> %s", req.RemoteAddr)
setHeaders(rw)
clientChannel := make(chan TailMessage)
server.addClient <- clientChannel
defer func() {
server.removeClient <- clientChannel
log.Printf("<--x %s", req.RemoteAddr)
}()
done := req.Context().Done()
go func() {
<-done // That is, pause until done channel is closed
server.removeClient <- clientChannel
log.Printf("<-- %s", req.RemoteAddr)
}()
messages := server.buffer.Get()
if len(messages) > 0 {
connect, err := json.Marshal(TailMessage{Context: "connect", Line: fmt.Sprintf("Backbuffer is %d lines", len(server.buffer.content))})
if err != nil {
log.Fatalf(err.Error())
}
fmt.Fprintf(rw, "data: %s\n\n", connect)
flusher.Flush()
for _, message := range messages {
msg, err := json.Marshal(message)
if err != nil {
log.Fatalf(err.Error())
}
fmt.Fprintf(rw, "data: %s\n\n", msg)
flusher.Flush()
}
}
for {
message := <-clientChannel
msg, err := json.Marshal(message)
if err != nil {
log.Fatalf(err.Error())
}
fmt.Fprintf(rw, "data: %s\n\n", msg)
flusher.Flush()
}
}
func setHeaders(rw http.ResponseWriter) {
rw.Header().Set("Content-Type", "text/event-stream")
rw.Header().Set("Connection", "keep-alive")
rw.Header().Set("Cache-Control", "no-cache")
rw.Header().Set("Access-Control-Allow-Origin", "*")
}
func (server *TailServer) ServeEmbed(rw http.ResponseWriter, req *http.Request, filename string, mimeType string) {
if server.useEmbedded {
rw.Header().Set("Content-Type", mimeType)
data, err := static.ReadFile("static/" + filename)
if err != nil {
http.Error(rw, "Not an embedded file: "+filename, http.StatusNotFound)
}
rw.WriteHeader(http.StatusOK)
rw.Write(data)
return
}
http.ServeFile(rw, req, "server/static/"+filename)
}
func (server *TailServer) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
switch req.URL.Path {
case "/":
server.ServeEmbed(rw, req, "index.html", "text/html")
case "/style.css":
server.ServeEmbed(rw, req, "style.css", "text/css")
case "/httptail.js":
server.ServeEmbed(rw, req, "httptail.js", "text/javascript")
case "/favicon.ico":
server.ServeEmbed(rw, req, "favicon.ico", "image/x-icon")
case "/events":
server.ServeEvents(rw, req)
default:
http.Error(rw, "Never heard of her.", http.StatusNotFound)
}
}