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// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
// All rights reserved. Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package main
import (
"bufio"
"io"
"os"
"os/exec"
"path/filepath"
"strings"
"sync"
"time"
)
var (
stdoutFirstLines []string // The first 10 lines of stdout
stdoutLastLines []string // The last 50 lines of stdout
stdoutMut sync.Mutex
)
const (
countRestarts = 5
loopThreshold = 15 * time.Second
)
func monitorMain() {
os.Setenv("STNORESTART", "yes")
l.SetPrefix("[monitor] ")
args := os.Args
var restarts [countRestarts]time.Time
for {
if t := time.Since(restarts[0]); t < loopThreshold {
l.Warnf("%d restarts in %v; not retrying further", countRestarts, t)
os.Exit(exitError)
}
copy(restarts[0:], restarts[1:])
restarts[len(restarts)-1] = time.Now()
cmd := exec.Command(args[0], args[1:]...)
stderr, err := cmd.StderrPipe()
if err != nil {
l.Fatalln(err)
}
stdout, err := cmd.StdoutPipe()
if err != nil {
l.Fatalln(err)
}
l.Infoln("Starting syncthing")
err = cmd.Start()
if err != nil {
l.Fatalln(err)
}
stdoutMut.Lock()
stdoutFirstLines = make([]string, 0, 10)
stdoutLastLines = make([]string, 0, 50)
stdoutMut.Unlock()
go copyStderr(stderr)
go copyStdout(stdout)
err = cmd.Wait()
if err == nil {
// Successfull exit indicates an intentional shutdown
return
}
l.Infoln("Syncthing exited:", err)
time.Sleep(1 * time.Second)
}
}
func copyStderr(stderr io.ReadCloser) {
br := bufio.NewReader(stderr)
var panicFd *os.File
for {
line, err := br.ReadString('\n')
if err != nil {
if err != io.EOF {
l.Warnln("stderr:", err)
}
return
}
if panicFd == nil {
os.Stderr.WriteString(line)
if strings.HasPrefix(line, "panic:") || strings.HasPrefix(line, "fatal error:") {
panicFd, err = os.Create(filepath.Join(confDir, time.Now().Format("panic-20060102-150405.log")))
if err != nil {
l.Warnln("Create panic log:", err)
continue
}
l.Warnf("Panic detected, writing to \"%s\"", panicFd.Name())
l.Warnln("Please create an issue at https://github.com/syncting/syncthing/issues/ with the panic log attached")
stdoutMut.Lock()
for _, line := range stdoutFirstLines {
panicFd.WriteString(line)
}
panicFd.WriteString("...\n")
for _, line := range stdoutLastLines {
panicFd.WriteString(line)
}
}
}
if panicFd != nil {
panicFd.WriteString(line)
}
}
}
func copyStdout(stderr io.ReadCloser) {
br := bufio.NewReader(stderr)
for {
line, err := br.ReadString('\n')
if err != nil {
if err != io.EOF {
l.Warnln("stdout:", err)
}
return
}
stdoutMut.Lock()
if len(stdoutFirstLines) < cap(stdoutFirstLines) {
stdoutFirstLines = append(stdoutFirstLines, line)
}
if l := len(stdoutLastLines); l == cap(stdoutLastLines) {
stdoutLastLines = stdoutLastLines[:l-1]
}
stdoutLastLines = append(stdoutLastLines, line)
stdoutMut.Unlock()
os.Stdout.WriteString(line)
}
}
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