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websocket_hub.go
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websocket_hub.go
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// Copyright 2016 Martin Hebnes Pedersen (LA5NTA). All rights reserved.
// Use of this source code is governed by the MIT-license that can be
// found in the LICENSE file.
package main
import (
"bufio"
"encoding/json"
"io"
"log"
"os"
"path"
"runtime"
"sync"
"time"
"github.com/fsnotify/fsnotify"
"github.com/gorilla/websocket"
"github.com/la5nta/pat/internal/osutil"
"github.com/la5nta/wl2k-go/mailbox"
)
// WSConn represent one connection in the WSHub pool
type WSConn struct {
conn *websocket.Conn
out chan interface{}
}
// WSHub is a hub for broadcasting data to several websocket connections
type WSHub struct {
mu sync.Mutex
pool map[*WSConn]struct{}
}
func NewWSHub() *WSHub {
w := &WSHub{pool: map[*WSConn]struct{}{}}
go w.watchMBox()
return w
}
func (w *WSHub) UpdateStatus() { w.WriteJSON(struct{ Status Status }{getStatus()}) }
func (w *WSHub) WriteProgress(p Progress) { w.WriteJSON(struct{ Progress Progress }{p}) }
func (w *WSHub) WriteNotification(n Notification) { w.WriteJSON(struct{ Notification Notification }{n}) }
func (w *WSHub) Prompt(p Prompt) {
w.WriteJSON(struct{ Prompt Prompt }{p})
go func() { <-p.cancel; w.WriteJSON(struct{ PromptAbort Prompt }{p}) }()
}
func (w *WSHub) WriteJSON(v interface{}) {
if w == nil {
return
}
w.mu.Lock()
for c, _ := range w.pool {
select {
case c.out <- v:
case <-time.After(3 * time.Second):
log.Println("Closing one unresponsive web socket")
c.conn.Close()
delete(w.pool, c)
}
}
w.mu.Unlock()
}
func (w *WSHub) ClientAddrs() []string {
if w == nil {
return nil
}
w.mu.Lock()
defer w.mu.Unlock()
addrs := make([]string, 0, len(w.pool))
for c, _ := range w.pool {
addrs = append(addrs, c.conn.RemoteAddr().String())
}
return addrs
}
func (w *WSHub) watchMBox() {
// Maximise ulimit -n:
// fsnotify opens a file descriptor for every file in the directories it watches, which
// may more files than the current soft limit. The is especially a problem on macOS which
// has a default soft limit of only 256 files. Windows does not have a such a limit.
if runtime.GOOS != "windows" {
if err := osutil.RaiseOpenFileLimit(4096); err != nil {
log.Printf("Unable to raise open file limit: %v", err)
}
}
fsWatcher, err := fsnotify.NewWatcher()
if err != nil {
log.Println("Unable to start fs watcher: ", err)
} else {
p := path.Join(mbox.MBoxPath, mailbox.DIR_INBOX)
if err := fsWatcher.Add(p); err != nil {
log.Printf("Unable to add path '%s' to fs watcher: %s", p, err)
}
// These will probably fail if the first failed, but it's not important to log all.
fsWatcher.Add(path.Join(mbox.MBoxPath, mailbox.DIR_OUTBOX))
fsWatcher.Add(path.Join(mbox.MBoxPath, mailbox.DIR_SENT))
fsWatcher.Add(path.Join(mbox.MBoxPath, mailbox.DIR_ARCHIVE))
defer fsWatcher.Close()
}
for {
select {
// Filesystem events
case <-fsWatcher.Events:
drainEvents(fsWatcher)
websocketHub.WriteJSON(struct {
UpdateMailbox bool
}{true})
case err := <-fsWatcher.Errors:
log.Println(err)
}
}
}
// Handle adds a new websocket to the hub
//
// It will block until the client either stops responding or closes the connection.
func (w *WSHub) Handle(conn *websocket.Conn) {
c := &WSConn{
conn: conn,
out: make(chan interface{}, 1),
}
w.mu.Lock()
w.pool[c] = struct{}{}
w.mu.Unlock()
// Initial status update
// (broadcasted as it includes info to other clients about this new one)
w.UpdateStatus()
quit := wsReadLoop(conn)
lines, done, err := tailFile(fOptions.LogPath)
if err != nil {
log.Println(err)
return
}
defer close(done)
for {
select {
case line := <-lines:
c.conn.WriteJSON(struct {
LogLine string
}{string(line)})
case v := <-c.out:
err := c.conn.WriteJSON(v)
if err != nil {
log.Println(err)
}
case <-quit:
// The read loop failed/disconnected. Remove from hub.
c.conn.Close()
w.mu.Lock()
delete(w.pool, c)
defer w.UpdateStatus()
w.mu.Unlock()
return
}
}
}
func drainEvents(w *fsnotify.Watcher) {
for {
select {
case <-w.Events:
default:
return
}
}
}
// Expects the file to never get renamed/truncated or deleted
func tailFile(path string) (<-chan []byte, chan<- struct{}, error) {
lines := make(chan []byte)
done := make(chan struct{})
file, err := os.Open(path)
if err != nil {
return nil, nil, err
}
go func() {
rd := bufio.NewReader(file)
for {
data, _, err := rd.ReadLine()
if err == io.EOF {
time.Sleep(time.Millisecond * 100)
continue
}
select {
case <-done:
file.Close()
return
case lines <- data:
}
}
}()
return (<-chan []byte)(lines), (chan<- struct{})(done), nil
}
func handleWSMessage(v map[string]json.RawMessage) {
raw, ok := v["prompt_response"]
if !ok {
return
}
var resp PromptResponse
json.Unmarshal(raw, &resp)
promptHub.Respond(resp.ID, resp.Value, resp.Err)
}
func wsReadLoop(c *websocket.Conn) <-chan struct{} {
quit := make(chan struct{})
go func() {
for {
v := map[string]json.RawMessage{}
err := c.ReadJSON(&v)
if err != nil {
close(quit)
return
}
go handleWSMessage(v)
}
}()
return quit
}