Go1.8实现watchdog功能,实现依赖启动服务程序

package mainimport (    "flag"    "fmt"    "log"    "os"    "os/signal"    "os/user"    "path"    "strconv"    "strings"    "sync"    "syscall"    "time"    "github.com/czxichen/command/watchdog"    conf "github.com/dlintw/goconf")//+build windows,linuxconst logDir = "./watchdog"func newProc(svc *Service, null, pw *os.File) *os.ProcAttr {    return &os.ProcAttr{Dir: svc.path, Files: []*os.File{null, pw, pw}}}func setPriority(pid, priority uintptr) syscall.Errno {    return 0}var (    logpath    = flag.String("log_path", "", "Specify log path")    configFile = flag.String("config", "watchdog.ini", "Watchdog configuration file"))func cfgOpt(cfg *conf.ConfigFile, section, option string) string {    if !cfg.HasOption(section, option) {        return ""    }    s, err := cfg.GetString(section, option)    if err != nil {        log.Fatalf("Failed to get %s for %s: %v", option, section, err)    }    return s}func svcOpt(cfg *conf.ConfigFile, service, option string, required bool) string {    opt := cfgOpt(cfg, service, option)    if opt == "" && required {        log.Fatalf("Service %s has missing %s option", service, option)    }    return opt}var signalNames = map[syscall.Signal]string{    syscall.SIGINT:  "SIGINT",    syscall.SIGQUIT: "SIGQUIT",    syscall.SIGTERM: "SIGTERM",}func signalName(s syscall.Signal) string {    if name, ok := signalNames[s]; ok {        return name    }    return fmt.Sprintf("SIG %d", s)}type Shutdowner interface {    Shutdown()}func shutdownHandler(server Shutdowner) {    sigc := make(chan os.Signal, 3)    signal.Notify(sigc, syscall.SIGINT, syscall.SIGQUIT, syscall.SIGTERM)    go func() {        for s := range sigc {            name := s.String()            if sig, ok := s.(syscall.Signal); ok {                name = signalName(sig)            }            log.Printf("Received %v, initiating shutdown...", name)            server.Shutdown()        }    }()}var (    restartDelay      = 2 * time.Second    restartBackoff    = 5 * time.Second    restartBackoffMax = 60 * time.Second)type Watchdog struct {    services map[string]*Service    shutdown chan bool}func NewWatchdog() *Watchdog {    return &Watchdog{        services: make(map[string]*Service),        shutdown: make(chan bool),    }}//关闭服务func (w *Watchdog) Shutdown() {    select {    case w.shutdown <- true:    default:    }}//添加服务,如果存在func (w *Watchdog) AddService(name, binary string) (*Service, error) {    if _, ok := w.services[name]; ok {        return nil, fmt.Errorf("Service %q already exists", name)    }    svc := newService(name, binary)    w.services[name] = svc    return svc, nil}//启动服务func (w *Watchdog) Walk() {    log.Printf("Seesaw watchdog starting...")    w.mapDependencies()    for _, svc := range w.services {        go svc.run()    }    <-w.shutdown    for _, svc := range w.services {        go svc.stop()    }    for _, svc := range w.services {        stopped := <-svc.stopped        svc.stopped <- stopped    }}//设置依赖关系func (w *Watchdog) mapDependencies() {    for name := range w.services {        svc := w.services[name]        for depName := range svc.dependencies {            dep, ok := w.services[depName]            if !ok {                log.Fatalf("Failed to find dependency %q for service %q", depName, name)            }            svc.dependencies[depName] = dep //依赖谁,依赖启动后才会启动自身            dep.dependents[svc.name] = svc  //谁依赖它,依赖它的服务退出后,才退出本身        }    }}//默认的优先级为0const prioProcess = 0//定义服务的类型.type Service struct {    name   string    binary string    path   string    args   []string    uid      uint32    gid      uint32    priority int    dependencies map[string]*Service    dependents   map[string]*Service    termTimeout time.Duration    lock    sync.Mutex    process *os.Process    done     chan bool    shutdown chan bool    started  chan bool    stopped  chan bool    failures uint64    restarts uint64    lastFailure time.Time    lastRestart time.Time}//初始化一个Service.func newService(name, binary string) *Service {    return &Service{        name:         name,        binary:       binary,        args:         make([]string, 0),        dependencies: make(map[string]*Service),        dependents:   make(map[string]*Service),        done:     make(chan bool),        shutdown: make(chan bool, 1),        started:  make(chan bool, 1),        stopped:  make(chan bool, 1),        termTimeout: 5 * time.Second,    }}//给这个服务添加依赖.func (svc *Service) AddDependency(name string) {    svc.dependencies[name] = nil}//为服务添加启动参数.func (svc *Service) AddArgs(args string) {    svc.args = strings.Fields(args)}//为进程设置优先级,Windows下面无效.func (svc *Service) SetPriority(priority int) error {    if priority < -20 || priority > 19 {        return fmt.Errorf("Invalid priority %d - must be between -20 and 19", priority)    }    svc.priority = priority    return nil}func (svc *Service) SetTermTimeout(tt time.Duration) {    svc.termTimeout = tt}func (svc *Service) SetUser(username string) error {    u, err := user.Lookup(username)    if err != nil {        return err    }    uid, err := strconv.Atoi(u.Uid)    if err != nil {        return err    }    gid, err := strconv.Atoi(u.Gid)    if err != nil {        return err    }    svc.uid = uint32(uid)    svc.gid = uint32(gid)    return nil}func (svc *Service) run() {    //如果存在依赖,要等依赖全部启动完毕之后才会自动自身.    for _, dep := range svc.dependencies {        log.Printf("Service %s waiting for %s to start", svc.name, dep.name)        select {        case started := <-dep.started:            dep.started <- started        case <-svc.shutdown:            goto done        }    }    for {        //如果启动失败,怎等待时间会延长,最大不超过restartBackoffMax时间        //程序启动必须是阻塞的,不然会重复运行        if svc.failures > 0 {            delay := time.Duration(svc.failures) * restartBackoff            if delay > restartBackoffMax {                delay = restartBackoffMax            }            log.Printf("Service %s has failed %d times - delaying %s before restart",                svc.name, svc.failures, delay)            select {            case <-time.After(delay):            case <-svc.shutdown:                goto done            }        }        svc.restarts++        svc.lastRestart = time.Now()        svc.runOnce()        select {        case <-time.After(restartDelay):        case <-svc.shutdown:            goto done        }    }done:    svc.done <- true}//为服务创建日志文件func (svc *Service) logFile() (*os.File, error) {    logName := svc.name + ".log"    if err := os.MkdirAll(logDir, 0666); err != nil {        if !os.IsExist(err) {            return nil, err        }    }    f, err := os.Create(path.Join(logDir, logName))    if err != nil {        return nil, err    }    fmt.Fprintf(f, "Log file for %s (stdout/stderr)\n", svc.name)    fmt.Fprintf(f, "Created at: %s\n", time.Now().Format("2006/01/02 15:04:05"))    return f, nil}//运行程序func (svc *Service) runOnce() {    args := make([]string, len(svc.args)+1)    args[0] = svc.name    copy(args[1:], svc.args)    fmt.Println("Args:", args)    null, err := os.Open(os.DevNull)    if err != nil {        log.Printf("Service %s - failed to open %s: %v", svc.name, os.DevNull, err)        return    }    lfile, err := svc.logFile()    if err != nil {        log.Printf("Service %s - failed to create log file: %v", svc.name, err)        null.Close()        return    }    attr := newProc(svc, null, lfile)    log.Printf("Starting service %s...", svc.name)    proc, err := os.StartProcess(svc.binary, args, attr)    if err != nil {        log.Printf("Service %s failed to start: %v", svc.name, err)        svc.lastFailure = time.Now()        svc.failures++        null.Close()        return    }    null.Close()    lfile.Close()    svc.lock.Lock()    svc.process = proc    svc.lock.Unlock()    if err := setPriority(uintptr(proc.Pid), uintptr(svc.priority)); err != 0 {        log.Printf("Failed to set priority to %d for service %s: %v", svc.priority, svc.name, err)    }    select {    case svc.started <- true:    default:    }    state, err := svc.process.Wait()    if err != nil {        log.Printf("Service %s wait failed with %v", svc.name, err)        svc.lastFailure = time.Now()        svc.failures++        return    }    if !state.Success() {        log.Printf("Service %s exited with %v", svc.name, state)        svc.lastFailure = time.Now()        svc.failures++        return    }    svc.failures = 0    log.Printf("Service %s exited normally.", svc.name)}//给进程发送信号func (svc *Service) signal(sig os.Signal) error {    svc.lock.Lock()    defer svc.lock.Unlock()    if svc.process == nil {        return nil    }    return svc.process.Signal(sig)}//停止服务func (svc *Service) stop() {    log.Printf("Stopping service %s...", svc.name)    //等待依赖它的进程退出完毕之后再退出自己.    for _, dep := range svc.dependents {        log.Printf("Service %s waiting for %s to stop", svc.name, dep.name)        stopped := <-dep.stopped        dep.stopped <- stopped    }    svc.shutdown <- true    //首先给进程发送退出信号,如果超时没有退出,则直接发送Kill信号.    svc.signal(syscall.SIGTERM)    select {    case <-svc.done:    case <-time.After(svc.termTimeout):        svc.signal(syscall.SIGKILL)        <-svc.done    }    log.Printf("Service %s stopped", svc.name)    svc.stopped <- true}func main() {    flag.Parse()    if *logpath == "" {        *logpath = os.Args[0] + ".log"    }    logFile, err := os.Create(*logpath)    if err != nil {        log.Fatalf("Create log file error:%s\n", err.Error())    }    defer logFile.Close()    log.SetOutput(logFile)    cfg, err := conf.ReadConfigFile(*configFile)    if err != nil {        log.Fatalf("Failed to read config file %q: %v", *configFile, err)    }    fido := watchdog.NewWatchdog()    shutdownHandler(fido)    for _, name := range cfg.GetSections() {        if name == "default" {            continue        }        binary := svcOpt(cfg, name, "binary", true)        args := svcOpt(cfg, name, "args", false)        svc, err := fido.AddService(name, binary)        if err != nil {            log.Fatalf("Failed to add service %q: %v", name, err)        }        svc.AddArgs(args)        if dep := svcOpt(cfg, name, "dependency", false); dep != "" {            svc.AddDependency(dep)        }        if opt := svcOpt(cfg, name, "priority", false); opt != "" {            prio, err := strconv.Atoi(opt)            if err != nil {                log.Fatalf("Service %s has invalid priority %q: %v", name, opt, err)            }            if err := svc.SetPriority(prio); err != nil {                log.Fatalf("Failed to set priority for service %s: %v", name, err)            }        }        if opt := svcOpt(cfg, name, "term_timeout", false); opt != "" {            tt, err := time.ParseDuration(opt)            if err != nil {                log.Fatalf("Service %s has invalid term_timeout %q: %v", name, opt, err)            }            svc.SetTermTimeout(tt)        }        if user := svcOpt(cfg, name, "user", false); user != "" {            if err := svc.SetUser(user); err != nil {                log.Fatalf("Failed to set user for service %s: %v", name, err)            }        }    }    fido.Walk()}