Support http service graceful restart (#416)

* support http service graceful restart

* fix dependencies

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}
-		err = server.ListenAndServeTLS(setting.CertFile, setting.KeyFile)
+		config := &tls.Config{
+			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:

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.

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)
+```
+
+

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{}
+}

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()
+}

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)
+}

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.

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.

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
+}

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.

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.

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.

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
+}

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")
+}

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.

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.

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

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
+}

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)
+}

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",