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Commit 34057069 authored by Brad Fitzpatrick's avatar Brad Fitzpatrick
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http2: reduce the number of select cases in serverConn.server 

This drops the number of select cases in serverConn.server from 10 to
6. It was 7 in Go 1.7. It increased to 10 in Go 1.8.

* replace testing-only testHookCh with always-on grab-bag serveMsgCh
  to be used for both test purposes, and infrequently used message
  types

* remove the settingsTimer.C case for the initial settings timer
  and use serveMsgCh and time.AfterFunc instead

* ... and do the same for the idle timeout timer.

* ... and for the shutdown timer.

* remove wantStartPushCh and just send the *startPushRequest to
  serveMsgCh too

I could go further with this (and plan to, later), but these are the
safe and easy ones that don't require more work elsewhere.

The speed gets better the more the request/response go via the
serverConn.serve loop. (once per Request.Body.Read or
ResponseWriter.Flush):

  name            old time/op    new time/op  delta
  ServerGets-4    138µs ± 3%     134µs ± 2%   -2.54%   (p=0.002 n=10+10)
  ServerPosts-4   176µs ±27%     154µs ± 2%   -12.62%  (p=0.011 n=10+10)

Updates kubernetes/kubernetes#45216
Updates golang/go#20302

Change-Id: I18019554089d7e3d76355d7137b5957e9597e803
Reviewed-on: https://go-review.googlesource.com/43034
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarTom Bergan <tombergan@google.com>
parent 84f0e6f9
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Inline Side-by-side
Showing with 62 additions and 35 deletions
http2/server.go
View file @ 34057069
......@@ -292,7 +292,7 @@ func (s *Server) ServeConn(c net.Conn, opts *ServeConnOpts) {
streams: make(map[uint32]*stream),
readFrameCh: make(chan readFrameResult),
wantWriteFrameCh: make(chan FrameWriteRequest, 8),
wantStartPushCh: make(chan startPushRequest, 8),
serveMsgCh: make(chan interface{}, 8),
wroteFrameCh: make(chan frameWriteResult, 1), // buffered; one send in writeFrameAsync
bodyReadCh: make(chan bodyReadMsg), // buffering doesn't matter either way
doneServing: make(chan struct{}),
......@@ -405,10 +405,9 @@ type serverConn struct {
doneServing chan struct{} // closed when serverConn.serve ends
readFrameCh chan readFrameResult // written by serverConn.readFrames
wantWriteFrameCh chan FrameWriteRequest // from handlers -> serve
wantStartPushCh chan startPushRequest // from handlers -> serve
wroteFrameCh chan frameWriteResult // from writeFrameAsync -> serve, tickles more frame writes
bodyReadCh chan bodyReadMsg // from handlers -> serve
testHookCh chan func(int) // code to run on the serve loop
serveMsgCh chan interface{} // misc messages & code to send to / run on the serve loop
flow flow // conn-wide (not stream-specific) outbound flow control
inflow flow // conn-wide inbound flow control
tlsState *tls.ConnectionState // shared by all handlers, like net/http
......@@ -440,10 +439,8 @@ type serverConn struct {
inFrameScheduleLoop bool // whether we're in the scheduleFrameWrite loop
needToSendGoAway bool // we need to schedule a GOAWAY frame write
goAwayCode ErrCode
shutdownTimerCh <-chan time.Time // nil until used
shutdownTimer *time.Timer // nil until used
idleTimer *time.Timer // nil if unused
idleTimerCh <-chan time.Time // nil if unused
shutdownTimer *time.Timer // nil until used
idleTimer *time.Timer // nil if unused
// Owned by the writeFrameAsync goroutine:
headerWriteBuf bytes.Buffer
......@@ -748,9 +745,8 @@ func (sc *serverConn) serve() {
sc.setConnState(http.StateIdle)
if sc.srv.IdleTimeout != 0 {
sc.idleTimer = time.NewTimer(sc.srv.IdleTimeout)
sc.idleTimer = time.AfterFunc(sc.srv.IdleTimeout, sc.onIdleTimer)
defer sc.idleTimer.Stop()
sc.idleTimerCh = sc.idleTimer.C
}
var gracefulShutdownCh chan struct{}
......@@ -764,7 +760,9 @@ func (sc *serverConn) serve() {
go sc.readFrames() // closed by defer sc.conn.Close above
settingsTimer := time.NewTimer(firstSettingsTimeout)
settingsTimer := time.AfterFunc(firstSettingsTimeout, sc.onSettingsTimer)
defer settingsTimer.Stop()
loopNum := 0
for {
loopNum++
......@@ -775,8 +773,6 @@ func (sc *serverConn) serve() {
break
}
sc.writeFrame(wr)
case spr := <-sc.wantStartPushCh:
sc.startPush(spr)
case res := <-sc.wroteFrameCh:
sc.wroteFrame(res)
case res := <-sc.readFrameCh:
......@@ -784,26 +780,38 @@ func (sc *serverConn) serve() {
return
}
res.readMore()
if settingsTimer.C != nil {
if settingsTimer != nil {
settingsTimer.Stop()
settingsTimer.C = nil
settingsTimer = nil
}
case m := <-sc.bodyReadCh:
sc.noteBodyRead(m.st, m.n)
case <-settingsTimer.C:
sc.logf("timeout waiting for SETTINGS frames from %v", sc.conn.RemoteAddr())
return
case <-gracefulShutdownCh:
gracefulShutdownCh = nil
sc.startGracefulShutdown()
case <-sc.shutdownTimerCh:
sc.vlogf("GOAWAY close timer fired; closing conn from %v", sc.conn.RemoteAddr())
return
case <-sc.idleTimerCh:
sc.vlogf("connection is idle")
sc.goAway(ErrCodeNo)
case fn := <-sc.testHookCh:
fn(loopNum)
case msg := <-sc.serveMsgCh:
switch v := msg.(type) {
case func(int):
v(loopNum) // for testing
case *timerMessage:
switch v {
case settingsTimerMsg:
sc.logf("timeout waiting for SETTINGS frames from %v", sc.conn.RemoteAddr())
return
case idleTimerMsg:
sc.vlogf("connection is idle")
sc.goAway(ErrCodeNo)
case shutdownTimerMsg:
sc.vlogf("GOAWAY close timer fired; closing conn from %v", sc.conn.RemoteAddr())
return
default:
panic("unknown timer")
}
case *startPushRequest:
sc.startPush(v)
default:
panic(fmt.Sprintf("unexpected type %T", v))
}
}
if sc.inGoAway && sc.curOpenStreams() == 0 && !sc.needToSendGoAway && !sc.writingFrame {
......@@ -820,6 +828,27 @@ func (sc *serverConn) awaitGracefulShutdown(sharedCh <-chan struct{}, privateCh
}
}
type timerMessage int
// Timeout message values sent to serveMsgCh.
var (
settingsTimerMsg = new(timerMessage)
idleTimerMsg = new(timerMessage)
shutdownTimerMsg = new(timerMessage)
)
func (sc *serverConn) onSettingsTimer() { sc.sendServeMsg(settingsTimerMsg) }
func (sc *serverConn) onIdleTimer() { sc.sendServeMsg(idleTimerMsg) }
func (sc *serverConn) onShutdownTimer() { sc.sendServeMsg(shutdownTimerMsg) }
func (sc *serverConn) sendServeMsg(msg interface{}) {
sc.serveG.checkNotOn() // NOT
select {
case sc.serveMsgCh <- msg:
case <-sc.doneServing:
}
}
// readPreface reads the ClientPreface greeting from the peer
// or returns an error on timeout or an invalid greeting.
func (sc *serverConn) readPreface() error {
......@@ -1172,8 +1201,7 @@ func (sc *serverConn) goAwayIn(code ErrCode, forceCloseIn time.Duration) {
func (sc *serverConn) shutDownIn(d time.Duration) {
sc.serveG.check()
sc.shutdownTimer = time.NewTimer(d)
sc.shutdownTimerCh = sc.shutdownTimer.C
sc.shutdownTimer = time.AfterFunc(d, sc.onShutdownTimer)
}
func (sc *serverConn) resetStream(se StreamError) {
......@@ -2551,7 +2579,7 @@ func (w *responseWriter) push(target string, opts pushOptions) error {
return fmt.Errorf("method %q must be GET or HEAD", opts.Method)
}
msg := startPushRequest{
msg := &startPushRequest{
parent: st,
method: opts.Method,
url: u,
......@@ -2564,7 +2592,7 @@ func (w *responseWriter) push(target string, opts pushOptions) error {
return errClientDisconnected
case <-st.cw:
return errStreamClosed
case sc.wantStartPushCh <- msg:
case sc.serveMsgCh <- msg:
}
select {
......@@ -2586,7 +2614,7 @@ type startPushRequest struct {
done chan error
}
func (sc *serverConn) startPush(msg startPushRequest) {
func (sc *serverConn) startPush(msg *startPushRequest) {
sc.serveG.check()
// http://tools.ietf.org/html/rfc7540#section-6.6.
......
http2/server_push_test.go
View file @ 34057069
......@@ -508,7 +508,7 @@ func TestServer_Push_RejectAfterGoAway(t *testing.T) {
return
default:
}
st.sc.testHookCh <- func(loopNum int) {
st.sc.serveMsgCh <- func(loopNum int) {
if !st.sc.pushEnabled {
readyOnce.Do(func() { close(ready) })
}
......
http2/server_test.go
View file @ 34057069
......@@ -142,7 +142,6 @@ func newServerTester(t testing.TB, handler http.HandlerFunc, opts ...interface{}
st.scMu.Lock()
defer st.scMu.Unlock()
st.sc = v
st.sc.testHookCh = make(chan func(int))
}
log.SetOutput(io.MultiWriter(stderrv(), twriter{t: t, st: st}))
if !onlyServer {
......@@ -187,7 +186,7 @@ func (st *serverTester) addLogFilter(phrase string) {
func (st *serverTester) stream(id uint32) *stream {
ch := make(chan *stream, 1)
st.sc.testHookCh <- func(int) {
st.sc.serveMsgCh <- func(int) {
ch <- st.sc.streams[id]
}
return <-ch
......@@ -195,7 +194,7 @@ func (st *serverTester) stream(id uint32) *stream {
func (st *serverTester) streamState(id uint32) streamState {
ch := make(chan streamState, 1)
st.sc.testHookCh <- func(int) {
st.sc.serveMsgCh <- func(int) {
state, _ := st.sc.state(id)
ch <- state
}
......@@ -205,7 +204,7 @@ func (st *serverTester) streamState(id uint32) streamState {
// loopNum reports how many times this conn's select loop has gone around.
func (st *serverTester) loopNum() int {
lastc := make(chan int, 1)
st.sc.testHookCh <- func(loopNum int) {
st.sc.serveMsgCh <- func(loopNum int) {
lastc <- loopNum
}
return <-lastc
......
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