377 lines
9.0 KiB
Go
377 lines
9.0 KiB
Go
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// Package httpdown provides http.ConnState enabled graceful termination of
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// http.Server.
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package httpdown
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import (
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"crypto/tls"
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"fmt"
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"net"
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"net/http"
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"os"
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"os/signal"
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"sync"
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"syscall"
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"time"
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"github.com/facebookgo/clock"
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"github.com/facebookgo/stats"
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)
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const (
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defaultStopTimeout = time.Minute
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defaultKillTimeout = time.Minute
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)
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// A Server allows encapsulates the process of accepting new connections and
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// serving them, and gracefully shutting down the listener without dropping
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// active connections.
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type Server interface {
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// Wait waits for the serving loop to finish. This will happen when Stop is
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// called, at which point it returns no error, or if there is an error in the
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// serving loop. You must call Wait after calling Serve or ListenAndServe.
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Wait() error
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// Stop stops the listener. It will block until all connections have been
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// closed.
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Stop() error
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}
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// HTTP defines the configuration for serving a http.Server. Multiple calls to
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// Serve or ListenAndServe can be made on the same HTTP instance. The default
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// timeouts of 1 minute each result in a maximum of 2 minutes before a Stop()
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// returns.
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type HTTP struct {
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// StopTimeout is the duration before we begin force closing connections.
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// Defaults to 1 minute.
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StopTimeout time.Duration
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// KillTimeout is the duration before which we completely give up and abort
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// even though we still have connected clients. This is useful when a large
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// number of client connections exist and closing them can take a long time.
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// Note, this is in addition to the StopTimeout. Defaults to 1 minute.
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KillTimeout time.Duration
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// Stats is optional. If provided, it will be used to record various metrics.
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Stats stats.Client
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// Clock allows for testing timing related functionality. Do not specify this
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// in production code.
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Clock clock.Clock
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}
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// Serve provides the low-level API which is useful if you're creating your own
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// net.Listener.
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func (h HTTP) Serve(s *http.Server, l net.Listener) Server {
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stopTimeout := h.StopTimeout
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if stopTimeout == 0 {
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stopTimeout = defaultStopTimeout
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}
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killTimeout := h.KillTimeout
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if killTimeout == 0 {
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killTimeout = defaultKillTimeout
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}
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klock := h.Clock
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if klock == nil {
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klock = clock.New()
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}
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ss := &server{
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stopTimeout: stopTimeout,
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killTimeout: killTimeout,
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stats: h.Stats,
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clock: klock,
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oldConnState: s.ConnState,
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listener: l,
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server: s,
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serveDone: make(chan struct{}),
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serveErr: make(chan error, 1),
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new: make(chan net.Conn),
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active: make(chan net.Conn),
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idle: make(chan net.Conn),
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closed: make(chan net.Conn),
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stop: make(chan chan struct{}),
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kill: make(chan chan struct{}),
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}
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s.ConnState = ss.connState
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go ss.manage()
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go ss.serve()
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return ss
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}
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// ListenAndServe returns a Server for the given http.Server. It is equivalent
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// to ListenAndServe from the standard library, but returns immediately.
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// Requests will be accepted in a background goroutine. If the http.Server has
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// a non-nil TLSConfig, a TLS enabled listener will be setup.
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func (h HTTP) ListenAndServe(s *http.Server) (Server, error) {
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addr := s.Addr
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if addr == "" {
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if s.TLSConfig == nil {
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addr = ":http"
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} else {
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addr = ":https"
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}
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}
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l, err := net.Listen("tcp", addr)
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if err != nil {
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stats.BumpSum(h.Stats, "listen.error", 1)
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return nil, err
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}
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if s.TLSConfig != nil {
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l = tls.NewListener(l, s.TLSConfig)
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}
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return h.Serve(s, l), nil
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}
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// server manages the serving process and allows for gracefully stopping it.
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type server struct {
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stopTimeout time.Duration
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killTimeout time.Duration
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stats stats.Client
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clock clock.Clock
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oldConnState func(net.Conn, http.ConnState)
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server *http.Server
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serveDone chan struct{}
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serveErr chan error
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listener net.Listener
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new chan net.Conn
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active chan net.Conn
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idle chan net.Conn
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closed chan net.Conn
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stop chan chan struct{}
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kill chan chan struct{}
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stopOnce sync.Once
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stopErr error
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}
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func (s *server) connState(c net.Conn, cs http.ConnState) {
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if s.oldConnState != nil {
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s.oldConnState(c, cs)
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}
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switch cs {
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case http.StateNew:
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s.new <- c
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case http.StateActive:
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s.active <- c
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case http.StateIdle:
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s.idle <- c
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case http.StateHijacked, http.StateClosed:
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s.closed <- c
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}
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}
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func (s *server) manage() {
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defer func() {
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close(s.new)
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close(s.active)
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close(s.idle)
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close(s.closed)
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close(s.stop)
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close(s.kill)
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}()
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var stopDone chan struct{}
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conns := map[net.Conn]http.ConnState{}
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var countNew, countActive, countIdle float64
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// decConn decrements the count associated with the current state of the
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// given connection.
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decConn := func(c net.Conn) {
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switch conns[c] {
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default:
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panic(fmt.Errorf("unknown existing connection: %s", c))
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case http.StateNew:
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countNew--
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case http.StateActive:
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countActive--
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case http.StateIdle:
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countIdle--
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}
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}
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// setup a ticker to report various values every minute. if we don't have a
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// Stats implementation provided, we Stop it so it never ticks.
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statsTicker := s.clock.Ticker(time.Minute)
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if s.stats == nil {
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statsTicker.Stop()
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}
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for {
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select {
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case <-statsTicker.C:
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// we'll only get here when s.stats is not nil
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s.stats.BumpAvg("http-state.new", countNew)
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s.stats.BumpAvg("http-state.active", countActive)
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s.stats.BumpAvg("http-state.idle", countIdle)
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s.stats.BumpAvg("http-state.total", countNew+countActive+countIdle)
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case c := <-s.new:
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conns[c] = http.StateNew
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countNew++
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case c := <-s.active:
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decConn(c)
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countActive++
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conns[c] = http.StateActive
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case c := <-s.idle:
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decConn(c)
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countIdle++
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conns[c] = http.StateIdle
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// if we're already stopping, close it
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if stopDone != nil {
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c.Close()
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}
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case c := <-s.closed:
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stats.BumpSum(s.stats, "conn.closed", 1)
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decConn(c)
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delete(conns, c)
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// if we're waiting to stop and are all empty, we just closed the last
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// connection and we're done.
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if stopDone != nil && len(conns) == 0 {
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close(stopDone)
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return
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}
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case stopDone = <-s.stop:
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// if we're already all empty, we're already done
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if len(conns) == 0 {
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close(stopDone)
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return
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}
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// close current idle connections right away
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for c, cs := range conns {
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if cs == http.StateIdle {
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c.Close()
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}
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}
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// continue the loop and wait for all the ConnState updates which will
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// eventually close(stopDone) and return from this goroutine.
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case killDone := <-s.kill:
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// force close all connections
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stats.BumpSum(s.stats, "kill.conn.count", float64(len(conns)))
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for c := range conns {
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c.Close()
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}
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// don't block the kill.
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close(killDone)
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// continue the loop and we wait for all the ConnState updates and will
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// return from this goroutine when we're all done. otherwise we'll try to
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// send those ConnState updates on closed channels.
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}
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}
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}
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func (s *server) serve() {
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stats.BumpSum(s.stats, "serve", 1)
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s.serveErr <- s.server.Serve(s.listener)
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close(s.serveDone)
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close(s.serveErr)
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}
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func (s *server) Wait() error {
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if err := <-s.serveErr; !isUseOfClosedError(err) {
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return err
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}
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return nil
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}
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func (s *server) Stop() error {
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s.stopOnce.Do(func() {
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defer stats.BumpTime(s.stats, "stop.time").End()
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stats.BumpSum(s.stats, "stop", 1)
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// first disable keep-alive for new connections
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s.server.SetKeepAlivesEnabled(false)
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// then close the listener so new connections can't connect come thru
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closeErr := s.listener.Close()
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<-s.serveDone
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// then trigger the background goroutine to stop and wait for it
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stopDone := make(chan struct{})
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s.stop <- stopDone
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// wait for stop
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select {
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case <-stopDone:
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case <-s.clock.After(s.stopTimeout):
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defer stats.BumpTime(s.stats, "kill.time").End()
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stats.BumpSum(s.stats, "kill", 1)
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// stop timed out, wait for kill
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killDone := make(chan struct{})
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s.kill <- killDone
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select {
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case <-killDone:
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case <-s.clock.After(s.killTimeout):
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// kill timed out, give up
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stats.BumpSum(s.stats, "kill.timeout", 1)
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}
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}
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if closeErr != nil && !isUseOfClosedError(closeErr) {
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stats.BumpSum(s.stats, "listener.close.error", 1)
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s.stopErr = closeErr
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}
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})
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return s.stopErr
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}
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func isUseOfClosedError(err error) bool {
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if err == nil {
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return false
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}
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if opErr, ok := err.(*net.OpError); ok {
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err = opErr.Err
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}
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return err.Error() == "use of closed network connection"
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}
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// ListenAndServe is a convenience function to serve and wait for a SIGTERM
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// or SIGINT before shutting down.
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func ListenAndServe(s *http.Server, hd *HTTP) error {
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if hd == nil {
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hd = &HTTP{}
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}
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hs, err := hd.ListenAndServe(s)
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if err != nil {
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return err
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}
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waiterr := make(chan error, 1)
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go func() {
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defer close(waiterr)
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waiterr <- hs.Wait()
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}()
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signals := make(chan os.Signal, 10)
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signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT)
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select {
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case err := <-waiterr:
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if err != nil {
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return err
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}
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case <-signals:
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signal.Stop(signals)
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if err := hs.Stop(); err != nil {
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return err
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}
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if err := <-waiterr; err != nil {
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return err
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}
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}
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return nil
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}
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