捕捉和处理信号可以实现优雅start和restart等。golang的signal提供了相关的方法。这里是一个模板，目录结构：
├── sig │ └── sig.go └── test.go
先看如何调用：
1.new出一个对象
2.register信号与对应的处理函数
3.定义os.Signal类型的channel，调用signal.Notify
4.for+select循环，原有逻辑放在default分支中。
package main
import (
. "./sig"
"fmt"
"os"
"os/signal"
"syscall"
"time"
)
var stopFlag_ bool
func main() {
sigHandler := SignalSetNew()
sigHandler.Register(syscall.SIGQUIT, sigHandlerFunc)
sigHandler.Register(syscall.SIGUSR1, sigHandlerFunc)
sigHandler.Register(syscall.SIGUSR2, sigHandlerFunc)
sigChan := make(chan os.Signal, 10)
signal.Notify(sigChan)
for true {
select {
case sig := <-sigChan:
err := sigHandler.Handle(sig, nil)
if err != nil {
fmt.Printf("[ERROR] unknown signal received: %v\n", sig)
os.Exit(1)
}
default:
time.Sleep(time.Duration(3) * time.Second)
}
}
}
func sigHandlerFunc(s os.Signal, arg interface{}) {
switch s {
case syscall.SIGUSR1: // check
fmt.Printf("stopping Status : %v\n", stopFlag_)
case syscall.SIGUSR2: // run
formerFlag := stopFlag_
stopFlag_ = false
fmt.Printf("stopping Status changed from %v to %v\n", formerFlag, stopFlag_)
case syscall.SIGQUIT: // stop
formerFlag := stopFlag_
stopFlag_ = true
fmt.Printf("stopping Status changed from %v to %v\n", formerFlag, stopFlag_)
}
}sig包（sig/sig.go）的定义：
package sig
import (
"fmt"
"os"
)
type SignalHandler func(s os.Signal, arg interface{})
type SignalSet struct {
m map[os.Signal]SignalHandler
}
func SignalSetNew() *SignalSet {
ss := new(SignalSet)
ss.m = make(map[os.Signal]SignalHandler)
return ss
}
func (set *SignalSet) Register(s os.Signal, handler SignalHandler) {
if _, found := set.m[s]; !found {
set.m[s] = handler
}
}
func (set *SignalSet) Handle(sig os.Signal, arg interface{}) (err error) {
if _, found := set.m[sig]; found {
set.m[sig](sig, arg)
return nil
} else {
return fmt.Errorf("No handler available for signal %v", sig)
}
panic("won't reach here")
}
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