forked from syncthing/syncthing
/
monitor.go
226 lines (187 loc) · 5.11 KB
/
monitor.go
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// Copyright (C) 2014 The Syncthing Authors.
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"bufio"
"io"
"os"
"os/exec"
"os/signal"
"path/filepath"
"runtime"
"strings"
"sync"
"syscall"
"time"
"github.com/syncthing/syncthing/internal/osutil"
)
var (
stdoutFirstLines []string // The first 10 lines of stdout
stdoutLastLines []string // The last 50 lines of stdout
stdoutMut sync.Mutex
)
const (
countRestarts = 4
loopThreshold = 60 * time.Second
)
func monitorMain() {
os.Setenv("STNORESTART", "yes")
os.Setenv("STMONITORED", "yes")
l.SetPrefix("[monitor] ")
var err error
var dst io.Writer = os.Stdout
if logFile != "" {
var fileDst io.Writer
fileDst, err = os.Create(logFile)
if err != nil {
l.Fatalln("log file:", err)
}
if runtime.GOOS == "windows" {
// Translate line breaks to Windows standard
fileDst = osutil.ReplacingWriter{
Writer: fileDst,
From: '\n',
To: []byte{'\r', '\n'},
}
}
// Log to both stdout and file.
dst = io.MultiWriter(dst, fileDst)
l.Infof(`Log output saved to file "%s"`, logFile)
}
args := os.Args
var restarts [countRestarts]time.Time
sign := make(chan os.Signal, 1)
sigTerm := syscall.Signal(0xf)
signal.Notify(sign, os.Interrupt, sigTerm, os.Kill)
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("stderr:", err)
}
stdout, err := cmd.StdoutPipe()
if err != nil {
l.Fatalln("stdout:", err)
}
l.Infoln("Starting syncthing")
err = cmd.Start()
if err != nil {
l.Fatalln(err)
}
// Let the next child process know that this is not the first time
// it's starting up.
os.Setenv("STRESTART", "yes")
stdoutMut.Lock()
stdoutFirstLines = make([]string, 0, 10)
stdoutLastLines = make([]string, 0, 50)
stdoutMut.Unlock()
go copyStderr(stderr, dst)
go copyStdout(stdout, dst)
exit := make(chan error)
go func() {
exit <- cmd.Wait()
}()
select {
case s := <-sign:
l.Infof("Signal %d received; exiting", s)
cmd.Process.Kill()
<-exit
return
case err = <-exit:
if err == nil {
// Successfull exit indicates an intentional shutdown
return
} else if exiterr, ok := err.(*exec.ExitError); ok {
if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
switch status.ExitStatus() {
case exitUpgrading:
// Restart the monitor process to release the .old
// binary as part of the upgrade process.
l.Infoln("Restarting monitor...")
os.Setenv("STNORESTART", "")
err := exec.Command(args[0], args[1:]...).Start()
if err != nil {
l.Warnln("restart:", err)
}
return
}
}
}
}
l.Infoln("Syncthing exited:", err)
time.Sleep(1 * time.Second)
}
}
func copyStderr(stderr io.ReadCloser, dst io.Writer) {
br := bufio.NewReader(stderr)
var panicFd *os.File
for {
line, err := br.ReadString('\n')
if err != nil {
return
}
if panicFd == nil {
dst.Write([]byte(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/syncthing/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)
}
stdoutMut.Unlock()
}
panicFd.WriteString("Panic at " + time.Now().Format(time.RFC3339) + "\n")
}
if panicFd != nil {
panicFd.WriteString(line)
}
}
}
func copyStdout(stdout io.ReadCloser, dst io.Writer) {
br := bufio.NewReader(stdout)
for {
line, err := br.ReadString('\n')
if err != nil {
return
}
stdoutMut.Lock()
if len(stdoutFirstLines) < cap(stdoutFirstLines) {
stdoutFirstLines = append(stdoutFirstLines, line)
} else {
if l := len(stdoutLastLines); l == cap(stdoutLastLines) {
stdoutLastLines = stdoutLastLines[:l-1]
}
stdoutLastLines = append(stdoutLastLines, line)
}
stdoutMut.Unlock()
dst.Write([]byte(line))
}
}