Support http service graceful restart (#416)

* support http service graceful restart * fix dependencies
8 years ago · 527c2dd665
parent fa60cf0ea4
commit 527c2dd665
20 changed files with 1919 additions and 3 deletions
--- a/cmd/web.go
+++ b/cmd/web.go
@ -31,6 +31,7 @@ import (
 	"code.gitea.io/gitea/routers/repo"
 	"code.gitea.io/gitea/routers/user"
 	"github.com/facebookgo/grace/gracehttp"
 	"github.com/go-macaron/binding"
 	"github.com/go-macaron/cache"
 	"github.com/go-macaron/captcha"
@ -615,10 +616,29 @@ func runWeb(ctx *cli.Context) error {
 	var err error
 	switch setting.Protocol {
 	case setting.HTTP:
-		err = http.ListenAndServe(listenAddr, m)
+		err = gracehttp.Serve(&http.Server{
 			Addr:    listenAddr,
 			Handler: m,
 		})
 	case setting.HTTPS:
-		server := &http.Server{Addr: listenAddr, TLSConfig: &tls.Config{MinVersion: tls.VersionTLS10}, Handler: m}
+		config := &tls.Config{
-		err = server.ListenAndServeTLS(setting.CertFile, setting.KeyFile)
+			MinVersion: tls.VersionTLS10,
 		}
 		if config.NextProtos == nil {
 			config.NextProtos = []string{"http/1.1"}
 		}
 		config.Certificates = make([]tls.Certificate, 1)
 		config.Certificates[0], err = tls.LoadX509KeyPair(setting.CertFile, setting.KeyFile)
 		if err != nil {
 			log.Fatal(4, "Failed to load https cert file %s: %v", listenAddr, err)
 		}
 		err = gracehttp.Serve(&http.Server{
 			Addr:      listenAddr,
 			Handler:   m,
 			TLSConfig: config,
 		})
 	case setting.FCGI:
 		err = fcgi.Serve(nil, m)
 	case setting.UnixSocket:
--- a/vendor/github.com/facebookgo/clock/LICENSE
+++ b/vendor/github.com/facebookgo/clock/LICENSE
@ -0,0 +1,21 @@
 The MIT License (MIT)
 Copyright (c) 2014 Ben Johnson
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
--- a/vendor/github.com/facebookgo/clock/README.md
+++ b/vendor/github.com/facebookgo/clock/README.md
@ -0,0 +1,104 @@
 clock [![Build Status](https://drone.io/github.com/benbjohnson/clock/status.png)](https://drone.io/github.com/benbjohnson/clock/latest) [![Coverage Status](https://coveralls.io/repos/benbjohnson/clock/badge.png?branch=master)](https://coveralls.io/r/benbjohnson/clock?branch=master) [![GoDoc](https://godoc.org/github.com/benbjohnson/clock?status.png)](https://godoc.org/github.com/benbjohnson/clock) ![Project status](http://img.shields.io/status/experimental.png?color=red)
 =====
 Clock is a small library for mocking time in Go. It provides an interface
 around the standard library's [`time`][time] package so that the application
 can use the realtime clock while tests can use the mock clock.
 [time]: http://golang.org/pkg/time/
 ## Usage
 ### Realtime Clock
 Your application can maintain a `Clock` variable that will allow realtime and
 mock clocks to be interchangable. For example, if you had an `Application` type:
 ```go
 import "github.com/benbjohnson/clock"
 type Application struct {
 	Clock clock.Clock
 }
 ```
 You could initialize it to use the realtime clock like this:
 ```go
 var app Application
 app.Clock = clock.New()
 ...
 ```
 Then all timers and time-related functionality should be performed from the
 `Clock` variable.
 ### Mocking time
 In your tests, you will want to use a `Mock` clock:
 ```go
 import (
 	"testing"
 	"github.com/benbjohnson/clock"
 )
 func TestApplication_DoSomething(t *testing.T) {
 	mock := clock.NewMock()
 	app := Application{Clock: mock}
 	...
 }
 ```
 Now that you've initialized your application to use the mock clock, you can
 adjust the time programmatically. The mock clock always starts from the Unix
 epoch (midnight, Jan 1, 1970 UTC).
 ### Controlling time
 The mock clock provides the same functions that the standard library's `time`
 package provides. For example, to find the current time, you use the `Now()`
 function:
 ```go
 mock := clock.NewMock()
 // Find the current time.
 mock.Now().UTC() // 1970-01-01 00:00:00 +0000 UTC
 // Move the clock forward.
 mock.Add(2 * time.Hour)
 // Check the time again. It's 2 hours later!
 mock.Now().UTC() // 1970-01-01 02:00:00 +0000 UTC
 ```
 Timers and Tickers are also controlled by this same mock clock. They will only
 execute when the clock is moved forward:
 ```
 mock := clock.NewMock()
 count := 0
 // Kick off a timer to increment every 1 mock second.
 go func() {
    ticker := clock.Ticker(1 * time.Second)
    for {
        <-ticker.C
        count++
    }
 }()
 runtime.Gosched()
 // Move the clock forward 10 second.
 mock.Add(10 * time.Second)
 // This prints 10.
 fmt.Println(count)
 ```
--- a/vendor/github.com/facebookgo/clock/clock.go
+++ b/vendor/github.com/facebookgo/clock/clock.go
@ -0,0 +1,363 @@
 package clock
 import (
 	"runtime"
 	"sort"
 	"sync"
 	"time"
 )
 // Clock represents an interface to the functions in the standard library time
 // package. Two implementations are available in the clock package. The first
 // is a real-time clock which simply wraps the time package's functions. The
 // second is a mock clock which will only make forward progress when
 // programmatically adjusted.
 type Clock interface {
 	After(d time.Duration) <-chan time.Time
 	AfterFunc(d time.Duration, f func()) *Timer
 	Now() time.Time
 	Sleep(d time.Duration)
 	Tick(d time.Duration) <-chan time.Time
 	Ticker(d time.Duration) *Ticker
 	Timer(d time.Duration) *Timer
 }
 // New returns an instance of a real-time clock.
 func New() Clock {
 	return &clock{}
 }
 // clock implements a real-time clock by simply wrapping the time package functions.
 type clock struct{}
 func (c *clock) After(d time.Duration) <-chan time.Time { return time.After(d) }
 func (c *clock) AfterFunc(d time.Duration, f func()) *Timer {
 	return &Timer{timer: time.AfterFunc(d, f)}
 }
 func (c *clock) Now() time.Time { return time.Now() }
 func (c *clock) Sleep(d time.Duration) { time.Sleep(d) }
 func (c *clock) Tick(d time.Duration) <-chan time.Time { return time.Tick(d) }
 func (c *clock) Ticker(d time.Duration) *Ticker {
 	t := time.NewTicker(d)
 	return &Ticker{C: t.C, ticker: t}
 }
 func (c *clock) Timer(d time.Duration) *Timer {
 	t := time.NewTimer(d)
 	return &Timer{C: t.C, timer: t}
 }
 // Mock represents a mock clock that only moves forward programmically.
 // It can be preferable to a real-time clock when testing time-based functionality.
 type Mock struct {
 	mu     sync.Mutex
 	now    time.Time   // current time
 	timers clockTimers // tickers & timers
 	calls      Calls
 	waiting    []waiting
 	callsMutex sync.Mutex
 }
 // NewMock returns an instance of a mock clock.
 // The current time of the mock clock on initialization is the Unix epoch.
 func NewMock() *Mock {
 	return &Mock{now: time.Unix(0, 0)}
 }
 // Add moves the current time of the mock clock forward by the duration.
 // This should only be called from a single goroutine at a time.
 func (m *Mock) Add(d time.Duration) {
 	// Calculate the final current time.
 	t := m.now.Add(d)
 	// Continue to execute timers until there are no more before the new time.
 	for {
 		if !m.runNextTimer(t) {
 			break
 		}
 	}
 	// Ensure that we end with the new time.
 	m.mu.Lock()
 	m.now = t
 	m.mu.Unlock()
 	// Give a small buffer to make sure the other goroutines get handled.
 	gosched()
 }
 // runNextTimer executes the next timer in chronological order and moves the
 // current time to the timer's next tick time. The next time is not executed if
 // it's next time if after the max time. Returns true if a timer is executed.
 func (m *Mock) runNextTimer(max time.Time) bool {
 	m.mu.Lock()
 	// Sort timers by time.
 	sort.Sort(m.timers)
 	// If we have no more timers then exit.
 	if len(m.timers) == 0 {
 		m.mu.Unlock()
 		return false
 	}
 	// Retrieve next timer. Exit if next tick is after new time.
 	t := m.timers[0]
 	if t.Next().After(max) {
 		m.mu.Unlock()
 		return false
 	}
 	// Move "now" forward and unlock clock.
 	m.now = t.Next()
 	m.mu.Unlock()
 	// Execute timer.
 	t.Tick(m.now)
 	return true
 }
 // After waits for the duration to elapse and then sends the current time on the returned channel.
 func (m *Mock) After(d time.Duration) <-chan time.Time {
 	defer m.inc(&m.calls.After)
 	return m.Timer(d).C
 }
 // AfterFunc waits for the duration to elapse and then executes a function.
 // A Timer is returned that can be stopped.
 func (m *Mock) AfterFunc(d time.Duration, f func()) *Timer {
 	defer m.inc(&m.calls.AfterFunc)
 	t := m.Timer(d)
 	t.C = nil
 	t.fn = f
 	return t
 }
 // Now returns the current wall time on the mock clock.
 func (m *Mock) Now() time.Time {
 	defer m.inc(&m.calls.Now)
 	m.mu.Lock()
 	defer m.mu.Unlock()
 	return m.now
 }
 // Sleep pauses the goroutine for the given duration on the mock clock.
 // The clock must be moved forward in a separate goroutine.
 func (m *Mock) Sleep(d time.Duration) {
 	defer m.inc(&m.calls.Sleep)
 	<-m.After(d)
 }
 // Tick is a convenience function for Ticker().
 // It will return a ticker channel that cannot be stopped.
 func (m *Mock) Tick(d time.Duration) <-chan time.Time {
 	defer m.inc(&m.calls.Tick)
 	return m.Ticker(d).C
 }
 // Ticker creates a new instance of Ticker.
 func (m *Mock) Ticker(d time.Duration) *Ticker {
 	defer m.inc(&m.calls.Ticker)
 	m.mu.Lock()
 	defer m.mu.Unlock()
 	ch := make(chan time.Time)
 	t := &Ticker{
 		C:    ch,
 		c:    ch,
 		mock: m,
 		d:    d,
 		next: m.now.Add(d),
 	}
 	m.timers = append(m.timers, (*internalTicker)(t))
 	return t
 }
 // Timer creates a new instance of Timer.
 func (m *Mock) Timer(d time.Duration) *Timer {
 	defer m.inc(&m.calls.Timer)
 	m.mu.Lock()
 	defer m.mu.Unlock()
 	ch := make(chan time.Time)
 	t := &Timer{
 		C:    ch,
 		c:    ch,
 		mock: m,
 		next: m.now.Add(d),
 	}
 	m.timers = append(m.timers, (*internalTimer)(t))
 	return t
 }
 func (m *Mock) removeClockTimer(t clockTimer) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 	for i, timer := range m.timers {
 		if timer == t {
 			copy(m.timers[i:], m.timers[i+1:])
 			m.timers[len(m.timers)-1] = nil
 			m.timers = m.timers[:len(m.timers)-1]
 			break
 		}
 	}
 	sort.Sort(m.timers)
 }
 func (m *Mock) inc(addr *uint32) {
 	m.callsMutex.Lock()
 	defer m.callsMutex.Unlock()
 	*addr++
 	var newWaiting []waiting
 	for _, w := range m.waiting {
 		if m.calls.atLeast(w.expected) {
 			close(w.done)
 			continue
 		}
 		newWaiting = append(newWaiting, w)
 	}
 	m.waiting = newWaiting
 }
 // Wait waits for at least the relevant calls before returning. The expected
 // Calls are always over the lifetime of the Mock. Values in the Calls struct
 // are used as the minimum number of calls, this allows you to wait for only
 // the calls you care about.
 func (m *Mock) Wait(s Calls) {
 	m.callsMutex.Lock()
 	if m.calls.atLeast(s) {
 		m.callsMutex.Unlock()
 		return
 	}
 	done := make(chan struct{})
 	m.waiting = append(m.waiting, waiting{expected: s, done: done})
 	m.callsMutex.Unlock()
 	<-done
 }
 // clockTimer represents an object with an associated start time.
 type clockTimer interface {
 	Next() time.Time
 	Tick(time.Time)
 }
 // clockTimers represents a list of sortable timers.
 type clockTimers []clockTimer
 func (a clockTimers) Len() int           { return len(a) }
 func (a clockTimers) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 func (a clockTimers) Less(i, j int) bool { return a[i].Next().Before(a[j].Next()) }
 // Timer represents a single event.
 // The current time will be sent on C, unless the timer was created by AfterFunc.
 type Timer struct {
 	C     <-chan time.Time
 	c     chan time.Time
 	timer *time.Timer // realtime impl, if set
 	next  time.Time   // next tick time
 	mock  *Mock       // mock clock, if set
 	fn    func()      // AfterFunc function, if set
 }
 // Stop turns off the ticker.
 func (t *Timer) Stop() {
 	if t.timer != nil {
 		t.timer.Stop()
 	} else {
 		t.mock.removeClockTimer((*internalTimer)(t))
 	}
 }
 type internalTimer Timer
 func (t *internalTimer) Next() time.Time { return t.next }
 func (t *internalTimer) Tick(now time.Time) {
 	if t.fn != nil {
 		t.fn()
 	} else {
 		t.c <- now
 	}
 	t.mock.removeClockTimer((*internalTimer)(t))
 	gosched()
 }
 // Ticker holds a channel that receives "ticks" at regular intervals.
 type Ticker struct {
 	C      <-chan time.Time
 	c      chan time.Time
 	ticker *time.Ticker  // realtime impl, if set
 	next   time.Time     // next tick time
 	mock   *Mock         // mock clock, if set
 	d      time.Duration // time between ticks
 }
 // Stop turns off the ticker.
 func (t *Ticker) Stop() {
 	if t.ticker != nil {
 		t.ticker.Stop()
 	} else {
 		t.mock.removeClockTimer((*internalTicker)(t))
 	}
 }
 type internalTicker Ticker
 func (t *internalTicker) Next() time.Time { return t.next }
 func (t *internalTicker) Tick(now time.Time) {
 	select {
 	case t.c <- now:
 	case <-time.After(1 * time.Millisecond):
 	}
 	t.next = now.Add(t.d)
 	gosched()
 }
 // Sleep momentarily so that other goroutines can process.
 func gosched() { runtime.Gosched() }
 // Calls keeps track of the count of calls for each of the methods on the Clock
 // interface.
 type Calls struct {
 	After     uint32
 	AfterFunc uint32
 	Now       uint32
 	Sleep     uint32
 	Tick      uint32
 	Ticker    uint32
 	Timer     uint32
 }
 // atLeast returns true if at least the number of calls in o have been made.
 func (c Calls) atLeast(o Calls) bool {
 	if c.After < o.After {
 		return false
 	}
 	if c.AfterFunc < o.AfterFunc {
 		return false
 	}
 	if c.Now < o.Now {
 		return false
 	}
 	if c.Sleep < o.Sleep {
 		return false
 	}
 	if c.Tick < o.Tick {
 		return false
 	}
 	if c.Ticker < o.Ticker {
 		return false
 	}
 	if c.Timer < o.Timer {
 		return false
 	}
 	return true
 }
 type waiting struct {
 	expected Calls
 	done     chan struct{}
 }
--- a/vendor/github.com/facebookgo/grace/gracehttp/http.go
+++ b/vendor/github.com/facebookgo/grace/gracehttp/http.go
@ -0,0 +1,186 @@
 // Package gracehttp provides easy to use graceful restart
 // functionality for HTTP server.
 package gracehttp
 import (
 	"bytes"
 	"crypto/tls"
 	"flag"
 	"fmt"
 	"log"
 	"net"
 	"net/http"
 	"os"
 	"os/signal"
 	"sync"
 	"syscall"
 	"github.com/facebookgo/grace/gracenet"
 	"github.com/facebookgo/httpdown"
 )
 var (
 	verbose    = flag.Bool("gracehttp.log", true, "Enable logging.")
 	didInherit = os.Getenv("LISTEN_FDS") != ""
 	ppid       = os.Getppid()
 )
 // An app contains one or more servers and associated configuration.
 type app struct {
 	servers   []*http.Server
 	http      *httpdown.HTTP
 	net       *gracenet.Net
 	listeners []net.Listener
 	sds       []httpdown.Server
 	errors    chan error
 }
 func newApp(servers []*http.Server) *app {
 	return &app{
 		servers:   servers,
 		http:      &httpdown.HTTP{},
 		net:       &gracenet.Net{},
 		listeners: make([]net.Listener, 0, len(servers)),
 		sds:       make([]httpdown.Server, 0, len(servers)),
 		// 2x num servers for possible Close or Stop errors + 1 for possible
 		// StartProcess error.
 		errors: make(chan error, 1+(len(servers)*2)),
 	}
 }
 func (a *app) listen() error {
 	for _, s := range a.servers {
 		// TODO: default addresses
 		l, err := a.net.Listen("tcp", s.Addr)
 		if err != nil {
 			return err
 		}
 		if s.TLSConfig != nil {
 			l = tls.NewListener(l, s.TLSConfig)
 		}
 		a.listeners = append(a.listeners, l)
 	}
 	return nil
 }
 func (a *app) serve() {
 	for i, s := range a.servers {
 		a.sds = append(a.sds, a.http.Serve(s, a.listeners[i]))
 	}
 }
 func (a *app) wait() {
 	var wg sync.WaitGroup
 	wg.Add(len(a.sds) * 2) // Wait & Stop
 	go a.signalHandler(&wg)
 	for _, s := range a.sds {
 		go func(s httpdown.Server) {
 			defer wg.Done()
 			if err := s.Wait(); err != nil {
 				a.errors <- err
 			}
 		}(s)
 	}
 	wg.Wait()
 }
 func (a *app) term(wg *sync.WaitGroup) {
 	for _, s := range a.sds {
 		go func(s httpdown.Server) {
 			defer wg.Done()
 			if err := s.Stop(); err != nil {
 				a.errors <- err
 			}
 		}(s)
 	}
 }
 func (a *app) signalHandler(wg *sync.WaitGroup) {
 	ch := make(chan os.Signal, 10)
 	signal.Notify(ch, syscall.SIGINT, syscall.SIGTERM, syscall.SIGUSR2)
 	for {
 		sig := <-ch
 		switch sig {
 		case syscall.SIGINT, syscall.SIGTERM:
 			// this ensures a subsequent INT/TERM will trigger standard go behaviour of
 			// terminating.
 			signal.Stop(ch)
 			a.term(wg)
 			return
 		case syscall.SIGUSR2:
 			// we only return here if there's an error, otherwise the new process
 			// will send us a TERM when it's ready to trigger the actual shutdown.
 			if _, err := a.net.StartProcess(); err != nil {
 				a.errors <- err
 			}
 		}
 	}
 }
 // Serve will serve the given http.Servers and will monitor for signals
 // allowing for graceful termination (SIGTERM) or restart (SIGUSR2).
 func Serve(servers ...*http.Server) error {
 	a := newApp(servers)
 	// Acquire Listeners
 	if err := a.listen(); err != nil {
 		return err
 	}
 	// Some useful logging.
 	if *verbose {
 		if didInherit {
 			if ppid == 1 {
 				log.Printf("Listening on init activated %s", pprintAddr(a.listeners))
 			} else {
 				const msg = "Graceful handoff of %s with new pid %d and old pid %d"
 				log.Printf(msg, pprintAddr(a.listeners), os.Getpid(), ppid)
 			}
 		} else {
 			const msg = "Serving %s with pid %d"
 			log.Printf(msg, pprintAddr(a.listeners), os.Getpid())
 		}
 	}
 	// Start serving.
 	a.serve()
 	// Close the parent if we inherited and it wasn't init that started us.
 	if didInherit && ppid != 1 {
 		if err := syscall.Kill(ppid, syscall.SIGTERM); err != nil {
 			return fmt.Errorf("failed to close parent: %s", err)
 		}
 	}
 	waitdone := make(chan struct{})
 	go func() {
 		defer close(waitdone)
 		a.wait()
 	}()
 	select {
 	case err := <-a.errors:
 		if err == nil {
 			panic("unexpected nil error")
 		}
 		return err
 	case <-waitdone:
 		if *verbose {
 			log.Printf("Exiting pid %d.", os.Getpid())
 		}
 		return nil
 	}
 }
 // Used for pretty printing addresses.
 func pprintAddr(listeners []net.Listener) []byte {
 	var out bytes.Buffer
 	for i, l := range listeners {
 		if i != 0 {
 			fmt.Fprint(&out, ", ")
 		}
 		fmt.Fprint(&out, l.Addr())
 	}
 	return out.Bytes()
 }
--- a/vendor/github.com/facebookgo/grace/gracenet/net.go
+++ b/vendor/github.com/facebookgo/grace/gracenet/net.go
@ -0,0 +1,252 @@
 // Package gracenet provides a family of Listen functions that either open a
 // fresh connection or provide an inherited connection from when the process
 // was started. The behave like their counterparts in the net package, but
 // transparently provide support for graceful restarts without dropping
 // connections. This is provided in a systemd socket activation compatible form
 // to allow using socket activation.
 //
 // BUG: Doesn't handle closing of listeners.
 package gracenet
 import (
 	"fmt"
 	"net"
 	"os"
 	"os/exec"
 	"strconv"
 	"strings"
 	"sync"
 )
 const (
 	// Used to indicate a graceful restart in the new process.
 	envCountKey       = "LISTEN_FDS"
 	envCountKeyPrefix = envCountKey + "="
 )
 // In order to keep the working directory the same as when we started we record
 // it at startup.
 var originalWD, _ = os.Getwd()
 // Net provides the family of Listen functions and maintains the associated
 // state. Typically you will have only once instance of Net per application.
 type Net struct {
 	inherited   []net.Listener
 	active      []net.Listener
 	mutex       sync.Mutex
 	inheritOnce sync.Once
 	// used in tests to override the default behavior of starting from fd 3.
 	fdStart int
 }
 func (n *Net) inherit() error {
 	var retErr error
 	n.inheritOnce.Do(func() {
 		n.mutex.Lock()
 		defer n.mutex.Unlock()
 		countStr := os.Getenv(envCountKey)
 		if countStr == "" {
 			return
 		}
 		count, err := strconv.Atoi(countStr)
 		if err != nil {
 			retErr = fmt.Errorf("found invalid count value: %s=%s", envCountKey, countStr)
 			return
 		}
 		// In tests this may be overridden.
 		fdStart := n.fdStart
 		if fdStart == 0 {
 			// In normal operations if we are inheriting, the listeners will begin at
 			// fd 3.
 			fdStart = 3
 		}
 		for i := fdStart; i < fdStart+count; i++ {
 			file := os.NewFile(uintptr(i), "listener")
 			l, err := net.FileListener(file)
 			if err != nil {
 				file.Close()
 				retErr = fmt.Errorf("error inheriting socket fd %d: %s", i, err)
 				return
 			}
 			if err := file.Close(); err != nil {
 				retErr = fmt.Errorf("error closing inherited socket fd %d: %s", i, err)
 				return
 			}
 			n.inherited = append(n.inherited, l)
 		}
 	})
 	return retErr
 }
 // Listen announces on the local network address laddr. The network net must be
 // a stream-oriented network: "tcp", "tcp4", "tcp6", "unix" or "unixpacket". It
 // returns an inherited net.Listener for the matching network and address, or
 // creates a new one using net.Listen.
 func (n *Net) Listen(nett, laddr string) (net.Listener, error) {
 	switch nett {
 	default:
 		return nil, net.UnknownNetworkError(nett)
 	case "tcp", "tcp4", "tcp6":
 		addr, err := net.ResolveTCPAddr(nett, laddr)
 		if err != nil {
 			return nil, err
 		}
 		return n.ListenTCP(nett, addr)
 	case "unix", "unixpacket", "invalid_unix_net_for_test":
 		addr, err := net.ResolveUnixAddr(nett, laddr)
 		if err != nil {
 			return nil, err
 		}
 		return n.ListenUnix(nett, addr)
 	}
 }
 // ListenTCP announces on the local network address laddr. The network net must
 // be: "tcp", "tcp4" or "tcp6". It returns an inherited net.Listener for the
 // matching network and address, or creates a new one using net.ListenTCP.
 func (n *Net) ListenTCP(nett string, laddr *net.TCPAddr) (*net.TCPListener, error) {
 	if err := n.inherit(); err != nil {
 		return nil, err
 	}
 	n.mutex.Lock()
 	defer n.mutex.Unlock()
 	// look for an inherited listener
 	for i, l := range n.inherited {
 		if l == nil { // we nil used inherited listeners
 			continue
 		}
 		if isSameAddr(l.Addr(), laddr) {
 			n.inherited[i] = nil
 			n.active = append(n.active, l)
 			return l.(*net.TCPListener), nil
 		}
 	}
 	// make a fresh listener
 	l, err := net.ListenTCP(nett, laddr)
 	if err != nil {
 		return nil, err
 	}
 	n.active = append(n.active, l)
 	return l, nil
 }
 // ListenUnix announces on the local network address laddr. The network net
 // must be a: "unix" or "unixpacket". It returns an inherited net.Listener for
 // the matching network and address, or creates a new one using net.ListenUnix.
 func (n *Net) ListenUnix(nett string, laddr *net.UnixAddr) (*net.UnixListener, error) {
 	if err := n.inherit(); err != nil {
 		return nil, err
 	}
 	n.mutex.Lock()
 	defer n.mutex.Unlock()
 	// look for an inherited listener
 	for i, l := range n.inherited {
 		if l == nil { // we nil used inherited listeners
 			continue
 		}
 		if isSameAddr(l.Addr(), laddr) {
 			n.inherited[i] = nil
 			n.active = append(n.active, l)
 			return l.(*net.UnixListener), nil
 		}
 	}
 	// make a fresh listener
 	l, err := net.ListenUnix(nett, laddr)
 	if err != nil {
 		return nil, err
 	}
 	n.active = append(n.active, l)
 	return l, nil
 }
 // activeListeners returns a snapshot copy of the active listeners.
 func (n *Net) activeListeners() ([]net.Listener, error) {
 	n.mutex.Lock()
 	defer n.mutex.Unlock()
 	ls := make([]net.Listener, len(n.active))
 	copy(ls, n.active)
 	return ls, nil
 }
 func isSameAddr(a1, a2 net.Addr) bool {
 	if a1.Network() != a2.Network() {
 		return false
 	}
 	a1s := a1.String()
 	a2s := a2.String()
 	if a1s == a2s {
 		return true
 	}
 	// This allows for ipv6 vs ipv4 local addresses to compare as equal. This
 	// scenario is common when listening on localhost.
 	const ipv6prefix = "[::]"
 	a1s = strings.TrimPrefix(a1s, ipv6prefix)
 	a2s = strings.TrimPrefix(a2s, ipv6prefix)
 	const ipv4prefix = "0.0.0.0"
 	a1s = strings.TrimPrefix(a1s, ipv4prefix)
 	a2s = strings.TrimPrefix(a2s, ipv4prefix)
 	return a1s == a2s
 }
 // StartProcess starts a new process passing it the active listeners. It
 // doesn't fork, but starts a new process using the same environment and
 // arguments as when it was originally started. This allows for a newly
 // deployed binary to be started. It returns the pid of the newly started
 // process when successful.
 func (n *Net) StartProcess() (int, error) {
 	listeners, err := n.activeListeners()
 	if err != nil {
 		return 0, err
 	}
 	// Extract the fds from the listeners.
 	files := make([]*os.File, len(listeners))
 	for i, l := range listeners {
 		files[i], err = l.(filer).File()
 		if err != nil {
 			return 0, err
 		}
 		defer files[i].Close()
 	}
 	// Use the original binary location. This works with symlinks such that if
 	// the file it points to has been changed we will use the updated symlink.
 	argv0, err := exec.LookPath(os.Args[0])
 	if err != nil {
 		return 0, err
 	}
 	// Pass on the environment and replace the old count key with the new one.
 	var env []string
 	for _, v := range os.Environ() {
 		if !strings.HasPrefix(v, envCountKeyPrefix) {
 			env = append(env, v)
 		}
 	}
 	env = append(env, fmt.Sprintf("%s%d", envCountKeyPrefix, len(listeners)))
 	allFiles := append([]*os.File{os.Stdin, os.Stdout, os.Stderr}, files...)
 	process, err := os.StartProcess(argv0, os.Args, &os.ProcAttr{
 		Dir:   originalWD,
 		Env:   env,
 		Files: allFiles,
 	})
 	if err != nil {
 		return 0, err
 	}
 	return process.Pid, nil
 }
 type filer interface {
 	File() (*os.File, error)
 }
--- a/vendor/github.com/facebookgo/grace/license
+++ b/vendor/github.com/facebookgo/grace/license
@ -0,0 +1,30 @@
 BSD License
 For grace software
 Copyright (c) 2015, Facebook, Inc. All rights reserved.
 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 * Neither the name Facebook nor the names of its contributors may be used to
   endorse or promote products derived from this software without specific
   prior written permission.
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--- a/vendor/github.com/facebookgo/grace/patents
+++ b/vendor/github.com/facebookgo/grace/patents
@ -0,0 +1,33 @@
 Additional Grant of Patent Rights Version 2
 "Software" means the grace software distributed by Facebook, Inc.
 Facebook, Inc. ("Facebook") hereby grants to each recipient of the Software
 ("you") a perpetual, worldwide, royalty-free, non-exclusive, irrevocable
 (subject to the termination provision below) license under any Necessary
 Claims, to make, have made, use, sell, offer to sell, import, and otherwise
 transfer the Software. For avoidance of doubt, no license is granted under
 Facebook’s rights in any patent claims that are infringed by (i) modifications
 to the Software made by you or any third party or (ii) the Software in
 combination with any software or other technology.
 The license granted hereunder will terminate, automatically and without notice,
 if you (or any of your subsidiaries, corporate affiliates or agents) initiate
 directly or indirectly, or take a direct financial interest in, any Patent
 Assertion: (i) against Facebook or any of its subsidiaries or corporate
 affiliates, (ii) against any party if such Patent Assertion arises in whole or
 in part from any software, technology, product or service of Facebook or any of
 its subsidiaries or corporate affiliates, or (iii) against any party relating
 to the Software. Notwithstanding the foregoing, if Facebook or any of its
 subsidiaries or corporate affiliates files a lawsuit alleging patent
 infringement against you in the first instance, and you respond by filing a
 patent infringement counterclaim in that lawsuit against that party that is
 unrelated to the Software, the license granted hereunder will not terminate
 under section (i) of this paragraph due to such counterclaim.
 A "Necessary Claim" is a claim of a patent owned by Facebook that is
 necessarily infringed by the Software standing alone.
 A "Patent Assertion" is any lawsuit or other action alleging direct, indirect,
 or contributory infringement or inducement to infringe any patent, including a
 cross-claim or counterclaim.
--- a/vendor/github.com/facebookgo/httpdown/httpdown.go
+++ b/vendor/github.com/facebookgo/httpdown/httpdown.go
@ -0,0 +1,376 @@
 // Package httpdown provides http.ConnState enabled graceful termination of
 // http.Server.
 package httpdown
 import (
 	"crypto/tls"
 	"fmt"
 	"net"
 	"net/http"
 	"os"
 	"os/signal"
 	"sync"
 	"syscall"
 	"time"
 	"github.com/facebookgo/clock"
 	"github.com/facebookgo/stats"
 )
 const (
 	defaultStopTimeout = time.Minute
 	defaultKillTimeout = time.Minute
 )
 // A Server allows encapsulates the process of accepting new connections and
 // serving them, and gracefully shutting down the listener without dropping
 // active connections.
 type Server interface {
 	// Wait waits for the serving loop to finish. This will happen when Stop is
 	// called, at which point it returns no error, or if there is an error in the
 	// serving loop. You must call Wait after calling Serve or ListenAndServe.
 	Wait() error
 	// Stop stops the listener. It will block until all connections have been
 	// closed.
 	Stop() error
 }
 // HTTP defines the configuration for serving a http.Server. Multiple calls to
 // Serve or ListenAndServe can be made on the same HTTP instance. The default
 // timeouts of 1 minute each result in a maximum of 2 minutes before a Stop()
 // returns.
 type HTTP struct {
 	// StopTimeout is the duration before we begin force closing connections.
 	// Defaults to 1 minute.
 	StopTimeout time.Duration
 	// KillTimeout is the duration before which we completely give up and abort
 	// even though we still have connected clients. This is useful when a large
 	// number of client connections exist and closing them can take a long time.
 	// Note, this is in addition to the StopTimeout. Defaults to 1 minute.
 	KillTimeout time.Duration
 	// Stats is optional. If provided, it will be used to record various metrics.
 	Stats stats.Client
 	// Clock allows for testing timing related functionality. Do not specify this
 	// in production code.
 	Clock clock.Clock
 }
 // Serve provides the low-level API which is useful if you're creating your own
 // net.Listener.
 func (h HTTP) Serve(s *http.Server, l net.Listener) Server {
 	stopTimeout := h.StopTimeout
 	if stopTimeout == 0 {
 		stopTimeout = defaultStopTimeout
 	}
 	killTimeout := h.KillTimeout
 	if killTimeout == 0 {
 		killTimeout = defaultKillTimeout
 	}
 	klock := h.Clock
 	if klock == nil {
 		klock = clock.New()
 	}
 	ss := &server{
 		stopTimeout:  stopTimeout,
 		killTimeout:  killTimeout,
 		stats:        h.Stats,
 		clock:        klock,
 		oldConnState: s.ConnState,
 		listener:     l,
 		server:       s,
 		serveDone:    make(chan struct{}),
 		serveErr:     make(chan error, 1),
 		new:          make(chan net.Conn),
 		active:       make(chan net.Conn),
 		idle:         make(chan net.Conn),
 		closed:       make(chan net.Conn),
 		stop:         make(chan chan struct{}),
 		kill:         make(chan chan struct{}),
 	}
 	s.ConnState = ss.connState
 	go ss.manage()
 	go ss.serve()
 	return ss
 }
 // ListenAndServe returns a Server for the given http.Server. It is equivalent
 // to ListenAndServe from the standard library, but returns immediately.
 // Requests will be accepted in a background goroutine. If the http.Server has
 // a non-nil TLSConfig, a TLS enabled listener will be setup.
 func (h HTTP) ListenAndServe(s *http.Server) (Server, error) {
 	addr := s.Addr
 	if addr == "" {
 		if s.TLSConfig == nil {
 			addr = ":http"
 		} else {
 			addr = ":https"
 		}
 	}
 	l, err := net.Listen("tcp", addr)
 	if err != nil {
 		stats.BumpSum(h.Stats, "listen.error", 1)
 		return nil, err
 	}
 	if s.TLSConfig != nil {
 		l = tls.NewListener(l, s.TLSConfig)
 	}
 	return h.Serve(s, l), nil
 }
 // server manages the serving process and allows for gracefully stopping it.
 type server struct {
 	stopTimeout time.Duration
 	killTimeout time.Duration
 	stats       stats.Client
 	clock       clock.Clock
 	oldConnState func(net.Conn, http.ConnState)
 	server       *http.Server
 	serveDone    chan struct{}
 	serveErr     chan error
 	listener     net.Listener
 	new    chan net.Conn
 	active chan net.Conn
 	idle   chan net.Conn
 	closed chan net.Conn
 	stop   chan chan struct{}
 	kill   chan chan struct{}
 	stopOnce sync.Once
 	stopErr  error
 }
 func (s *server) connState(c net.Conn, cs http.ConnState) {
 	if s.oldConnState != nil {
 		s.oldConnState(c, cs)
 	}
 	switch cs {
 	case http.StateNew:
 		s.new <- c
 	case http.StateActive:
 		s.active <- c
 	case http.StateIdle:
 		s.idle <- c
 	case http.StateHijacked, http.StateClosed:
 		s.closed <- c
 	}
 }
 func (s *server) manage() {
 	defer func() {
 		close(s.new)
 		close(s.active)
 		close(s.idle)
 		close(s.closed)
 		close(s.stop)
 		close(s.kill)
 	}()
 	var stopDone chan struct{}
 	conns := map[net.Conn]http.ConnState{}
 	var countNew, countActive, countIdle float64
 	// decConn decrements the count associated with the current state of the
 	// given connection.
 	decConn := func(c net.Conn) {
 		switch conns[c] {
 		default:
 			panic(fmt.Errorf("unknown existing connection: %s", c))
 		case http.StateNew:
 			countNew--
 		case http.StateActive:
 			countActive--
 		case http.StateIdle:
 			countIdle--
 		}
 	}
 	// setup a ticker to report various values every minute. if we don't have a
 	// Stats implementation provided, we Stop it so it never ticks.
 	statsTicker := s.clock.Ticker(time.Minute)
 	if s.stats == nil {
 		statsTicker.Stop()
 	}
 	for {
 		select {
 		case <-statsTicker.C:
 			// we'll only get here when s.stats is not nil
 			s.stats.BumpAvg("http-state.new", countNew)
 			s.stats.BumpAvg("http-state.active", countActive)
 			s.stats.BumpAvg("http-state.idle", countIdle)
 			s.stats.BumpAvg("http-state.total", countNew+countActive+countIdle)
 		case c := <-s.new:
 			conns[c] = http.StateNew
 			countNew++
 		case c := <-s.active:
 			decConn(c)
 			countActive++
 			conns[c] = http.StateActive
 		case c := <-s.idle:
 			decConn(c)
 			countIdle++
 			conns[c] = http.StateIdle
 			// if we're already stopping, close it
 			if stopDone != nil {
 				c.Close()
 			}
 		case c := <-s.closed:
 			stats.BumpSum(s.stats, "conn.closed", 1)
 			decConn(c)
 			delete(conns, c)
 			// if we're waiting to stop and are all empty, we just closed the last
 			// connection and we're done.
 			if stopDone != nil && len(conns) == 0 {
 				close(stopDone)
 				return
 			}
 		case stopDone = <-s.stop:
 			// if we're already all empty, we're already done
 			if len(conns) == 0 {
 				close(stopDone)
 				return
 			}
 			// close current idle connections right away
 			for c, cs := range conns {
 				if cs == http.StateIdle {
 					c.Close()
 				}
 			}
 			// continue the loop and wait for all the ConnState updates which will
 			// eventually close(stopDone) and return from this goroutine.
 		case killDone := <-s.kill:
 			// force close all connections
 			stats.BumpSum(s.stats, "kill.conn.count", float64(len(conns)))
 			for c := range conns {
 				c.Close()
 			}
 			// don't block the kill.
 			close(killDone)
 			// continue the loop and we wait for all the ConnState updates and will
 			// return from this goroutine when we're all done. otherwise we'll try to
 			// send those ConnState updates on closed channels.
 		}
 	}
 }
 func (s *server) serve() {
 	stats.BumpSum(s.stats, "serve", 1)
 	s.serveErr <- s.server.Serve(s.listener)
 	close(s.serveDone)
 	close(s.serveErr)
 }
 func (s *server) Wait() error {
 	if err := <-s.serveErr; !isUseOfClosedError(err) {
 		return err
 	}
 	return nil
 }
 func (s *server) Stop() error {
 	s.stopOnce.Do(func() {
 		defer stats.BumpTime(s.stats, "stop.time").End()
 		stats.BumpSum(s.stats, "stop", 1)
 		// first disable keep-alive for new connections
 		s.server.SetKeepAlivesEnabled(false)
 		// then close the listener so new connections can't connect come thru
 		closeErr := s.listener.Close()
 		<-s.serveDone
 		// then trigger the background goroutine to stop and wait for it
 		stopDone := make(chan struct{})
 		s.stop <- stopDone
 		// wait for stop
 		select {
 		case <-stopDone:
 		case <-s.clock.After(s.stopTimeout):
 			defer stats.BumpTime(s.stats, "kill.time").End()
 			stats.BumpSum(s.stats, "kill", 1)
 			// stop timed out, wait for kill
 			killDone := make(chan struct{})
 			s.kill <- killDone
 			select {
 			case <-killDone:
 			case <-s.clock.After(s.killTimeout):
 				// kill timed out, give up
 				stats.BumpSum(s.stats, "kill.timeout", 1)
 			}
 		}
 		if closeErr != nil && !isUseOfClosedError(closeErr) {
 			stats.BumpSum(s.stats, "listener.close.error", 1)
 			s.stopErr = closeErr
 		}
 	})
 	return s.stopErr
 }
 func isUseOfClosedError(err error) bool {
 	if err == nil {
 		return false
 	}
 	if opErr, ok := err.(*net.OpError); ok {
 		err = opErr.Err
 	}
 	return err.Error() == "use of closed network connection"
 }
 // ListenAndServe is a convenience function to serve and wait for a SIGTERM
 // or SIGINT before shutting down.
 func ListenAndServe(s *http.Server, hd *HTTP) error {
 	if hd == nil {
 		hd = &HTTP{}
 	}
 	hs, err := hd.ListenAndServe(s)
 	if err != nil {
 		return err
 	}
 	waiterr := make(chan error, 1)
 	go func() {
 		defer close(waiterr)
 		waiterr <- hs.Wait()
 	}()
 	signals := make(chan os.Signal, 10)
 	signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT)
 	select {
 	case err := <-waiterr:
 		if err != nil {
 			return err
 		}
 	case <-signals:
 		signal.Stop(signals)
 		if err := hs.Stop(); err != nil {
 			return err
 		}
 		if err := <-waiterr; err != nil {
 			return err
 		}
 	}
 	return nil
 }
--- a/vendor/github.com/facebookgo/httpdown/license
+++ b/vendor/github.com/facebookgo/httpdown/license
@ -0,0 +1,30 @@
 BSD License
 For httpdown software
 Copyright (c) 2015, Facebook, Inc. All rights reserved.
 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 * Neither the name Facebook nor the names of its contributors may be used to
   endorse or promote products derived from this software without specific
   prior written permission.
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--- a/vendor/github.com/facebookgo/httpdown/patents
+++ b/vendor/github.com/facebookgo/httpdown/patents
@ -0,0 +1,33 @@
 Additional Grant of Patent Rights Version 2
 "Software" means the httpdown software distributed by Facebook, Inc.
 Facebook, Inc. ("Facebook") hereby grants to each recipient of the Software
 ("you") a perpetual, worldwide, royalty-free, non-exclusive, irrevocable
 (subject to the termination provision below) license under any Necessary
 Claims, to make, have made, use, sell, offer to sell, import, and otherwise
 transfer the Software. For avoidance of doubt, no license is granted under
 Facebook’s rights in any patent claims that are infringed by (i) modifications
 to the Software made by you or any third party or (ii) the Software in
 combination with any software or other technology.
 The license granted hereunder will terminate, automatically and without notice,
 if you (or any of your subsidiaries, corporate affiliates or agents) initiate
 directly or indirectly, or take a direct financial interest in, any Patent
 Assertion: (i) against Facebook or any of its subsidiaries or corporate
 affiliates, (ii) against any party if such Patent Assertion arises in whole or
 in part from any software, technology, product or service of Facebook or any of
 its subsidiaries or corporate affiliates, or (iii) against any party relating
 to the Software. Notwithstanding the foregoing, if Facebook or any of its
 subsidiaries or corporate affiliates files a lawsuit alleging patent
 infringement against you in the first instance, and you respond by filing a
 patent infringement counterclaim in that lawsuit against that party that is
 unrelated to the Software, the license granted hereunder will not terminate
 under section (i) of this paragraph due to such counterclaim.
 A "Necessary Claim" is a claim of a patent owned by Facebook that is
 necessarily infringed by the Software standing alone.
 A "Patent Assertion" is any lawsuit or other action alleging direct, indirect,
 or contributory infringement or inducement to infringe any patent, including a
 cross-claim or counterclaim.
--- a/vendor/github.com/facebookgo/httpdown/readme.md
+++ b/vendor/github.com/facebookgo/httpdown/readme.md
@ -0,0 +1,41 @@
 httpdown [![Build Status](https://secure.travis-ci.org/facebookgo/httpdown.png)](https://travis-ci.org/facebookgo/httpdown)
 ========
 Documentation: https://godoc.org/github.com/facebookgo/httpdown
 Package httpdown provides a library that makes it easy to build a HTTP server
 that can be shutdown gracefully (that is, without dropping any connections).
 If you want graceful restart and not just graceful shutdown, look at the
 [grace](https://github.com/facebookgo/grace) package which uses this package
 underneath but also provides graceful restart.
 Usage
 -----
 Demo HTTP Server with graceful termination:
 https://github.com/facebookgo/httpdown/blob/master/httpdown_example/main.go
 1. Install the demo application
        go get github.com/facebookgo/httpdown/httpdown_example
 1. Start it in the first terminal
        httpdown_example
   This will output something like:
        2014/11/18 21:57:50 serving on http://127.0.0.1:8080/ with pid 17
 1. In a second terminal start a slow HTTP request
        curl 'http://localhost:8080/?duration=20s'
 1. In a third terminal trigger a graceful shutdown (using the pid from your output):
        kill -TERM 17
 This will demonstrate that the slow request was served before the server was
 shutdown. You could also have used `Ctrl-C` instead of `kill` as the example
 application triggers graceful shutdown on TERM or INT signals.
--- a/vendor/github.com/facebookgo/stats/aggregation.go
+++ b/vendor/github.com/facebookgo/stats/aggregation.go
@ -0,0 +1,35 @@
 package stats
 import "sort"
 // Average returns the average value
 func Average(values []float64) float64 {
 	if len(values) == 0 {
 		return 0
 	}
 	var val float64
 	for _, point := range values {
 		val += point
 	}
 	return val / float64(len(values))
 }
 // Sum returns the sum of all the given values
 func Sum(values []float64) float64 {
 	var val float64
 	for _, point := range values {
 		val += point
 	}
 	return val
 }
 // Percentiles returns a map containing the asked for percentiles
 func Percentiles(values []float64, percentiles map[string]float64) map[string]float64 {
 	sort.Float64s(values)
 	results := map[string]float64{}
 	for label, p := range percentiles {
 		results[label] = values[int(float64(len(values))*p)]
 	}
 	return results
 }
--- a/vendor/github.com/facebookgo/stats/counter.go
+++ b/vendor/github.com/facebookgo/stats/counter.go
@ -0,0 +1,112 @@
 package stats
 import "fmt"
 // Type is the type of aggregation of apply
 type Type int
 const (
 	AggregateAvg Type = iota
 	AggregateSum
 	AggregateHistogram
 )
 var (
 	// HistogramPercentiles is used to determine which percentiles to return for
 	// SimpleCounter.Aggregate
 	HistogramPercentiles = map[string]float64{
 		"p50": 0.5,
 		"p95": 0.95,
 		"p99": 0.99,
 	}
 	// MinSamplesForPercentiles is used by SimpleCounter.Aggregate to determine
 	// what the minimum number of samples is required for percentile analysis
 	MinSamplesForPercentiles = 10
 )
 // Aggregates can be used to merge counters together. This is not goroutine safe
 type Aggregates map[string]Counter
 // Add adds the counter for aggregation. This is not goroutine safe
 func (a Aggregates) Add(c Counter) error {
 	key := c.FullKey()
 	if counter, ok := a[key]; ok {
 		if counter.GetType() != c.GetType() {
 			return fmt.Errorf("stats: mismatched aggregation type for: %s", key)
 		}
 		counter.AddValues(c.GetValues()...)
 	} else {
 		a[key] = c
 	}
 	return nil
 }
 // Counter is the interface used by Aggregates to merge counters together
 type Counter interface {
 	// FullKey is used to uniquely identify the counter
 	FullKey() string
 	// AddValues adds values for aggregation
 	AddValues(...float64)
 	// GetValues returns the values for aggregation
 	GetValues() []float64
 	// GetType returns the type of aggregation to apply
 	GetType() Type
 }
 // SimpleCounter is a basic implementation of the Counter interface
 type SimpleCounter struct {
 	Key    string
 	Values []float64
 	Type   Type
 }
 // FullKey is part of the Counter interace
 func (s *SimpleCounter) FullKey() string {
 	return s.Key
 }
 // GetValues is part of the Counter interface
 func (s *SimpleCounter) GetValues() []float64 {
 	return s.Values
 }
 // AddValues is part of the Counter interface
 func (s *SimpleCounter) AddValues(vs ...float64) {
 	s.Values = append(s.Values, vs...)
 }
 // GetType is part of the Counter interface
 func (s *SimpleCounter) GetType() Type {
 	return s.Type
 }
 // Aggregate aggregates the provided values appropriately, returning a map
 // from key to value. If AggregateHistogram is specified, the map will contain
 // the relevant percentiles as specified by HistogramPercentiles
 func (s *SimpleCounter) Aggregate() map[string]float64 {
 	switch s.Type {
 	case AggregateAvg:
 		return map[string]float64{
 			s.Key: Average(s.Values),
 		}
 	case AggregateSum:
 		return map[string]float64{
 			s.Key: Sum(s.Values),
 		}
 	case AggregateHistogram:
 		histogram := map[string]float64{
 			s.Key: Average(s.Values),
 		}
 		if len(s.Values) > MinSamplesForPercentiles {
 			for k, v := range Percentiles(s.Values, HistogramPercentiles) {
 				histogram[fmt.Sprintf("%s.%s", s.Key, k)] = v
 			}
 		}
 		return histogram
 	}
 	panic("stats: unsupported aggregation type")
 }
--- a/vendor/github.com/facebookgo/stats/license
+++ b/vendor/github.com/facebookgo/stats/license
@ -0,0 +1,30 @@
 BSD License
 For stats software
 Copyright (c) 2015, Facebook, Inc. All rights reserved.
 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 * Neither the name Facebook nor the names of its contributors may be used to
   endorse or promote products derived from this software without specific
   prior written permission.
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--- a/vendor/github.com/facebookgo/stats/patents
+++ b/vendor/github.com/facebookgo/stats/patents
@ -0,0 +1,33 @@
 Additional Grant of Patent Rights Version 2
 "Software" means the stats software distributed by Facebook, Inc.
 Facebook, Inc. ("Facebook") hereby grants to each recipient of the Software
 ("you") a perpetual, worldwide, royalty-free, non-exclusive, irrevocable
 (subject to the termination provision below) license under any Necessary
 Claims, to make, have made, use, sell, offer to sell, import, and otherwise
 transfer the Software. For avoidance of doubt, no license is granted under
 Facebook’s rights in any patent claims that are infringed by (i) modifications
 to the Software made by you or any third party or (ii) the Software in
 combination with any software or other technology.
 The license granted hereunder will terminate, automatically and without notice,
 if you (or any of your subsidiaries, corporate affiliates or agents) initiate
 directly or indirectly, or take a direct financial interest in, any Patent
 Assertion: (i) against Facebook or any of its subsidiaries or corporate
 affiliates, (ii) against any party if such Patent Assertion arises in whole or
 in part from any software, technology, product or service of Facebook or any of
 its subsidiaries or corporate affiliates, or (iii) against any party relating
 to the Software. Notwithstanding the foregoing, if Facebook or any of its
 subsidiaries or corporate affiliates files a lawsuit alleging patent
 infringement against you in the first instance, and you respond by filing a
 patent infringement counterclaim in that lawsuit against that party that is
 unrelated to the Software, the license granted hereunder will not terminate
 under section (i) of this paragraph due to such counterclaim.
 A "Necessary Claim" is a claim of a patent owned by Facebook that is
 necessarily infringed by the Software standing alone.
 A "Patent Assertion" is any lawsuit or other action alleging direct, indirect,
 or contributory infringement or inducement to infringe any patent, including a
 cross-claim or counterclaim.
--- a/vendor/github.com/facebookgo/stats/readme.md
+++ b/vendor/github.com/facebookgo/stats/readme.md
@ -0,0 +1,4 @@
 stats [![Build Status](https://secure.travis-ci.org/facebookgo/stats.png)](https://travis-ci.org/facebookgo/stats)
 =====
 Documentation: https://godoc.org/github.com/facebookgo/stats
--- a/vendor/github.com/facebookgo/stats/stats.go
+++ b/vendor/github.com/facebookgo/stats/stats.go
@ -0,0 +1,166 @@
 // Package stats defines a lightweight interface for collecting statistics. It
 // doesn't provide an implementation, just the shared interface.
 package stats
 // Client provides methods to collection statistics.
 type Client interface {
 	// BumpAvg bumps the average for the given key.
 	BumpAvg(key string, val float64)
 	// BumpSum bumps the sum for the given key.
 	BumpSum(key string, val float64)
 	// BumpHistogram bumps the histogram for the given key.
 	BumpHistogram(key string, val float64)
 	// BumpTime is a special version of BumpHistogram which is specialized for
 	// timers. Calling it starts the timer, and it returns a value on which End()
 	// can be called to indicate finishing the timer. A convenient way of
 	// recording the duration of a function is calling it like such at the top of
 	// the function:
 	//
 	//     defer s.BumpTime("my.function").End()
 	BumpTime(key string) interface {
 		End()
 	}
 }
 // PrefixClient adds multiple keys for the same value, with each prefix
 // added to the key and calls the underlying client.
 func PrefixClient(prefixes []string, client Client) Client {
 	return &prefixClient{
 		Prefixes: prefixes,
 		Client:   client,
 	}
 }
 type prefixClient struct {
 	Prefixes []string
 	Client   Client
 }
 func (p *prefixClient) BumpAvg(key string, val float64) {
 	for _, prefix := range p.Prefixes {
 		p.Client.BumpAvg(prefix+key, val)
 	}
 }
 func (p *prefixClient) BumpSum(key string, val float64) {
 	for _, prefix := range p.Prefixes {
 		p.Client.BumpSum(prefix+key, val)
 	}
 }
 func (p *prefixClient) BumpHistogram(key string, val float64) {
 	for _, prefix := range p.Prefixes {
 		p.Client.BumpHistogram(prefix+key, val)
 	}
 }
 func (p *prefixClient) BumpTime(key string) interface {
 	End()
 } {
 	var m multiEnder
 	for _, prefix := range p.Prefixes {
 		m = append(m, p.Client.BumpTime(prefix+key))
 	}
 	return m
 }
 // multiEnder combines many enders together.
 type multiEnder []interface {
 	End()
 }
 func (m multiEnder) End() {
 	for _, e := range m {
 		e.End()
 	}
 }
 // HookClient is useful for testing. It provides optional hooks for each
 // expected method in the interface, which if provided will be called. If a
 // hook is not provided, it will be ignored.
 type HookClient struct {
 	BumpAvgHook       func(key string, val float64)
 	BumpSumHook       func(key string, val float64)
 	BumpHistogramHook func(key string, val float64)
 	BumpTimeHook      func(key string) interface {
 		End()
 	}
 }
 // BumpAvg will call BumpAvgHook if defined.
 func (c *HookClient) BumpAvg(key string, val float64) {
 	if c.BumpAvgHook != nil {
 		c.BumpAvgHook(key, val)
 	}
 }
 // BumpSum will call BumpSumHook if defined.
 func (c *HookClient) BumpSum(key string, val float64) {
 	if c.BumpSumHook != nil {
 		c.BumpSumHook(key, val)
 	}
 }
 // BumpHistogram will call BumpHistogramHook if defined.
 func (c *HookClient) BumpHistogram(key string, val float64) {
 	if c.BumpHistogramHook != nil {
 		c.BumpHistogramHook(key, val)
 	}
 }
 // BumpTime will call BumpTimeHook if defined.
 func (c *HookClient) BumpTime(key string) interface {
 	End()
 } {
 	if c.BumpTimeHook != nil {
 		return c.BumpTimeHook(key)
 	}
 	return NoOpEnd
 }
 type noOpEnd struct{}
 func (n noOpEnd) End() {}
 // NoOpEnd provides a dummy value for use in tests as valid return value for
 // BumpTime().
 var NoOpEnd = noOpEnd{}
 // BumpAvg calls BumpAvg on the Client if it isn't nil. This is useful when a
 // component has an optional stats.Client.
 func BumpAvg(c Client, key string, val float64) {
 	if c != nil {
 		c.BumpAvg(key, val)
 	}
 }
 // BumpSum calls BumpSum on the Client if it isn't nil. This is useful when a
 // component has an optional stats.Client.
 func BumpSum(c Client, key string, val float64) {
 	if c != nil {
 		c.BumpSum(key, val)
 	}
 }
 // BumpHistogram calls BumpHistogram on the Client if it isn't nil. This is
 // useful when a component has an optional stats.Client.
 func BumpHistogram(c Client, key string, val float64) {
 	if c != nil {
 		c.BumpHistogram(key, val)
 	}
 }
 // BumpTime calls BumpTime on the Client if it isn't nil. If the Client is nil
 // it still returns a valid return value which will be a no-op. This is useful
 // when a component has an optional stats.Client.
 func BumpTime(c Client, key string) interface {
 	End()
 } {
 	if c != nil {
 		return c.BumpTime(key)
 	}
 	return NoOpEnd
 }
--- a/vendor/github.com/facebookgo/stats/stopper.go
+++ b/vendor/github.com/facebookgo/stats/stopper.go
@ -0,0 +1,17 @@
 package stats
 import "time"
 // Stopper calls Client.BumpSum and Client.BumpHistogram when End'ed
 type Stopper struct {
 	Key    string
 	Start  time.Time
 	Client Client
 }
 // End the Stopper
 func (s *Stopper) End() {
 	since := time.Since(s.Start).Seconds() * 1000.0
 	s.Client.BumpSum(s.Key+".total", since)
 	s.Client.BumpHistogram(s.Key, since)
 }
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@ -92,6 +92,36 @@
 			"revision": "57eb5e1fc594ad4b0b1dbea7b286d299e0cb43c2",
 			"revisionTime": "2015-12-24T04:54:52Z"
 		},
 		{
 			"checksumSHA1": "imR2wF388/0fBU6RRWx8RvTi8Q8=",
 			"path": "github.com/facebookgo/clock",
 			"revision": "600d898af40aa09a7a93ecb9265d87b0504b6f03",
 			"revisionTime": "2015-04-10T01:09:13Z"
 		},
 		{
 			"checksumSHA1": "j2O1k8Kvw6btFkJKt45nQQuAHM0=",
 			"path": "github.com/facebookgo/grace/gracehttp",
 			"revision": "5729e484473f52048578af1b80d0008c7024089b",
 			"revisionTime": "2016-09-26T23:17:15Z"
 		},
 		{
 			"checksumSHA1": "nj3ykV8Em7WOfvHNIo/XNTT9LOM=",
 			"path": "github.com/facebookgo/grace/gracenet",
 			"revision": "5729e484473f52048578af1b80d0008c7024089b",
 			"revisionTime": "2016-09-26T23:17:15Z"
 		},
 		{
 			"checksumSHA1": "8SgB/r3Cf+OvXmg8bIPnlEq03Bs=",
 			"path": "github.com/facebookgo/httpdown",
 			"revision": "a3b1354551a26449fbe05f5d855937f6e7acbd71",
 			"revisionTime": "2016-03-23T22:10:27Z"
 		},
 		{
 			"checksumSHA1": "SzXvrWxavFo8HD/2hnbdu17C3VE=",
 			"path": "github.com/facebookgo/stats",
 			"revision": "1b76add642e42c6ffba7211ad7b3939ce654526e",
 			"revisionTime": "2015-10-06T22:16:25Z"
 		},
 		{
 			"checksumSHA1": "qTJizMr1DBhDTZiRNmC+khEClz8=",
 			"path": "github.com/go-macaron/bindata",