mirror of
https://github.com/soypat/lneto.git
synced 2026-08-08 17:03:40 +00:00
Patricio Whittingslow
109 lines
2.9 KiB
Go
109 lines
2.9 KiB
Go
//go:build !tinygo && linux
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package main
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import (
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"log/slog"
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"os"
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"strconv"
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"sync/atomic"
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"time"
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"github.com/soypat/lneto/http/httphi"
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"github.com/soypat/lneto/x/rawsock"
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)
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const (
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kB = 1 << 10
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listenPort = 8080
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bufferSizes = 2 * kB
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// A browser sends around twenty header fields; a request carrying more
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// than this is answered 431 rather than parsed into memory it was not
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// given. Each field costs 8 bytes of table.
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numHeaderFields = 32
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numGoroutines = 4
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readTimeout = 2 * time.Second
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)
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func main() {
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if err := run(); err != nil {
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println("Error:", err.Error())
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os.Exit(1)
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}
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println("DONE")
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}
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func run() error {
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var ln rawsock.Listener
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err := ln.Listen(listenPort)
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if err != nil {
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return err
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}
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defer ln.Close()
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print("listening on http://localhost:", listenPort, "\n")
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var mux httphi.MuxSlice
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mux.Handle("GET /", homepage)
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var router httphi.Router
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err = router.Configure(httphi.RouterConfig{
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FixedNumGoroutines: numGoroutines,
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RequestHeaderBufferSize: bufferSizes,
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RequestNumHeaderKVCap: numHeaderFields,
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ResponseHeaderMinBufferSize: bufferSizes,
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MaxAwaitingConns: 256,
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Mux: &mux,
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Logger: slog.Default(),
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})
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if err != nil {
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return err
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}
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defer router.TeardownGoroutines()
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for {
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conn := new(rawsock.Conn)
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err := ln.AcceptConn(conn)
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if err != nil {
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return err
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}
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// The connection owns the idle policy: a peer that opens a socket and
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// then stalls fails its read instead of holding a router goroutine.
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conn.SetReadTimeout(readTimeout)
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err = router.Handle(conn)
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if err != nil {
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// Every goroutine is busy and the queue is full. Dropping the
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// connection is the backpressure: memory stays bounded.
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slog.Warn("dropped connection", slog.String("remote", conn.RemoteAddr().String()), slog.String("err", err.Error()))
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conn.Close()
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}
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}
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}
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const (
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htmlHead = `<html><body bgcolor="#000080" text="#00FF00"><center>` +
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`<marquee><font face="Comic Sans MS" size="5" color="#FFFF00">` +
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`*** WELCOME TO MY HOMEPAGE ***</font></marquee>` +
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`<h1><blink>YOU ARE VISITOR #`
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htmlTail = `!</blink></h1>` +
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`<font color="#FF00FF">Sign my guestbook!</font>` +
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`<br><hr>Best viewed in Netscape Navigator</center></body></html>`
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// maxPage bounds the rendered page: both halves plus the visitor number.
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maxPage = len(htmlHead) + 20 + len(htmlTail)
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)
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// visits counts served requests. Handlers run on the router's goroutines, so
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// every visitor gets their own number.
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var visits atomic.Uint64
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func homepage(exch *httphi.Exchange) {
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var page [maxPage]byte
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n := copy(page[:], htmlHead)
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n += len(strconv.AppendUint(page[n:n], visits.Add(1), 10))
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n += copy(page[n:], htmlTail)
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exch.StageHeader("Content-Type", "text/html")
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exch.StageHeaderInt("Content-Length", int64(n), 10)
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exch.WriteHeader(int(httphi.StatusOK))
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exch.WriteBody(page[:n])
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}
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