168 lines
4.1 KiB
Go
168 lines
4.1 KiB
Go
/*
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* Minimalist Object Storage, (C) 2015 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// Package nimble provides easy to use graceful restart for a set of HTTP services
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//
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// This package originally from https://github.com/facebookgo/grace
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//
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// Re-licensing with Apache License 2.0, with code modifications
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package nimble
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import (
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"crypto/tls"
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"net"
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"net/http"
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"os"
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"os/signal"
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"sync"
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"syscall"
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"time"
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"github.com/facebookgo/httpdown"
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"github.com/minio/minio/pkg/iodine"
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)
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// An app contains one or more servers and their associated configuration.
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type app struct {
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servers []*http.Server
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listeners []net.Listener
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sds []httpdown.Server
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net *nimbleNet
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errors chan error
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}
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// listen initailize listeners
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func (a *app) listen() error {
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for _, s := range a.servers {
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l, err := a.net.Listen("tcp", s.Addr)
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if err != nil {
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return iodine.New(err, nil)
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}
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if s.TLSConfig != nil {
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l = tls.NewListener(l, s.TLSConfig)
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}
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a.listeners = append(a.listeners, l)
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}
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return nil
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}
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// serve start serving all listeners
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func (a *app) serve() {
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h := &httpdown.HTTP{
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StopTimeout: 10 * time.Second,
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KillTimeout: 1 * time.Second,
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}
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for i, s := range a.servers {
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a.sds = append(a.sds, h.Serve(s, a.listeners[i]))
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}
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}
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// wait for http server to signal all requests that have been served
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func (a *app) wait() {
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var wg sync.WaitGroup
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wg.Add(len(a.sds) * 2) // Wait & Stop
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go a.trapSignal(&wg)
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for _, s := range a.sds {
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go func(s httpdown.Server) {
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defer wg.Done()
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if err := s.Wait(); err != nil {
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a.errors <- iodine.New(err, nil)
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}
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}(s)
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}
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wg.Wait()
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}
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// trapSignal wait on listed signals for pre-defined behaviors
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func (a *app) trapSignal(wg *sync.WaitGroup) {
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ch := make(chan os.Signal, 10)
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signal.Notify(ch, syscall.SIGTERM, syscall.SIGUSR2, syscall.SIGHUP)
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for {
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sig := <-ch
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switch sig {
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case syscall.SIGTERM:
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// this ensures a subsequent TERM will trigger standard go behaviour of terminating
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signal.Stop(ch)
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// roll through all initialized http servers and stop them
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for _, s := range a.sds {
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go func(s httpdown.Server) {
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defer wg.Done()
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if err := s.Stop(); err != nil {
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a.errors <- iodine.New(err, nil)
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}
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}(s)
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}
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return
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case syscall.SIGUSR2:
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fallthrough
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case syscall.SIGHUP:
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// we only return here if there's an error, otherwise the new process
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// will send us a TERM when it's ready to trigger the actual shutdown.
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if _, err := a.net.StartProcess(); err != nil {
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a.errors <- iodine.New(err, nil)
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}
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}
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}
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}
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// ListenAndServe will serve the given http.Servers and will monitor for signals
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// allowing for graceful termination (SIGTERM) or restart (SIGUSR2/SIGHUP).
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func ListenAndServe(servers ...*http.Server) error {
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// get parent process id
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ppid := os.Getppid()
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a := &app{
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servers: servers,
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listeners: make([]net.Listener, 0, len(servers)),
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sds: make([]httpdown.Server, 0, len(servers)),
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net: &nimbleNet{},
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errors: make(chan error, 1+(len(servers)*2)),
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}
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// Acquire Listeners
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if err := a.listen(); err != nil {
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return iodine.New(err, nil)
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}
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// Start serving.
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a.serve()
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// Close the parent if we inherited and it wasn't init that started us.
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if os.Getenv("LISTEN_FDS") != "" && ppid != 1 {
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if err := syscall.Kill(ppid, syscall.SIGTERM); err != nil {
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return iodine.New(err, nil)
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}
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}
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waitdone := make(chan struct{})
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go func() {
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defer close(waitdone)
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a.wait()
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// communicate by sending not by closing a channel
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waitdone <- struct{}{}
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}()
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select {
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case err := <-a.errors:
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if err == nil {
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panic("unexpected nil error")
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}
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return iodine.New(err, nil)
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case <-waitdone:
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return nil
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}
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}
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