mirror of
https://github.com/restic/restic.git
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853 lines
21 KiB
Go
853 lines
21 KiB
Go
/*
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*
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* Copyright 2014 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package transport
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import (
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"bytes"
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"fmt"
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"runtime"
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"sync"
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"golang.org/x/net/http2"
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"golang.org/x/net/http2/hpack"
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)
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var updateHeaderTblSize = func(e *hpack.Encoder, v uint32) {
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e.SetMaxDynamicTableSizeLimit(v)
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}
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type itemNode struct {
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it interface{}
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next *itemNode
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}
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type itemList struct {
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head *itemNode
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tail *itemNode
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}
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func (il *itemList) enqueue(i interface{}) {
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n := &itemNode{it: i}
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if il.tail == nil {
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il.head, il.tail = n, n
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return
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}
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il.tail.next = n
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il.tail = n
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}
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// peek returns the first item in the list without removing it from the
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// list.
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func (il *itemList) peek() interface{} {
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return il.head.it
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}
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func (il *itemList) dequeue() interface{} {
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if il.head == nil {
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return nil
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}
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i := il.head.it
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il.head = il.head.next
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if il.head == nil {
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il.tail = nil
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}
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return i
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}
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func (il *itemList) dequeueAll() *itemNode {
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h := il.head
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il.head, il.tail = nil, nil
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return h
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}
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func (il *itemList) isEmpty() bool {
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return il.head == nil
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}
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// The following defines various control items which could flow through
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// the control buffer of transport. They represent different aspects of
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// control tasks, e.g., flow control, settings, streaming resetting, etc.
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// registerStream is used to register an incoming stream with loopy writer.
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type registerStream struct {
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streamID uint32
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wq *writeQuota
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}
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// headerFrame is also used to register stream on the client-side.
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type headerFrame struct {
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streamID uint32
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hf []hpack.HeaderField
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endStream bool // Valid on server side.
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initStream func(uint32) (bool, error) // Used only on the client side.
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onWrite func()
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wq *writeQuota // write quota for the stream created.
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cleanup *cleanupStream // Valid on the server side.
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onOrphaned func(error) // Valid on client-side
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}
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type cleanupStream struct {
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streamID uint32
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rst bool
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rstCode http2.ErrCode
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onWrite func()
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}
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type dataFrame struct {
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streamID uint32
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endStream bool
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h []byte
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d []byte
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// onEachWrite is called every time
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// a part of d is written out.
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onEachWrite func()
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}
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type incomingWindowUpdate struct {
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streamID uint32
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increment uint32
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}
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type outgoingWindowUpdate struct {
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streamID uint32
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increment uint32
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}
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type incomingSettings struct {
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ss []http2.Setting
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}
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type outgoingSettings struct {
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ss []http2.Setting
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}
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type incomingGoAway struct {
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}
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type goAway struct {
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code http2.ErrCode
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debugData []byte
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headsUp bool
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closeConn bool
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}
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type ping struct {
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ack bool
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data [8]byte
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}
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type outFlowControlSizeRequest struct {
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resp chan uint32
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}
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type outStreamState int
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const (
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active outStreamState = iota
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empty
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waitingOnStreamQuota
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)
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type outStream struct {
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id uint32
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state outStreamState
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itl *itemList
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bytesOutStanding int
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wq *writeQuota
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next *outStream
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prev *outStream
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}
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func (s *outStream) deleteSelf() {
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if s.prev != nil {
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s.prev.next = s.next
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}
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if s.next != nil {
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s.next.prev = s.prev
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}
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s.next, s.prev = nil, nil
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}
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type outStreamList struct {
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// Following are sentinel objects that mark the
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// beginning and end of the list. They do not
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// contain any item lists. All valid objects are
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// inserted in between them.
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// This is needed so that an outStream object can
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// deleteSelf() in O(1) time without knowing which
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// list it belongs to.
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head *outStream
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tail *outStream
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}
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func newOutStreamList() *outStreamList {
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head, tail := new(outStream), new(outStream)
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head.next = tail
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tail.prev = head
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return &outStreamList{
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head: head,
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tail: tail,
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}
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}
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func (l *outStreamList) enqueue(s *outStream) {
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e := l.tail.prev
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e.next = s
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s.prev = e
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s.next = l.tail
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l.tail.prev = s
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}
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// remove from the beginning of the list.
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func (l *outStreamList) dequeue() *outStream {
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b := l.head.next
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if b == l.tail {
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return nil
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}
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b.deleteSelf()
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return b
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}
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// controlBuffer is a way to pass information to loopy.
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// Information is passed as specific struct types called control frames.
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// A control frame not only represents data, messages or headers to be sent out
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// but can also be used to instruct loopy to update its internal state.
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// It shouldn't be confused with an HTTP2 frame, although some of the control frames
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// like dataFrame and headerFrame do go out on wire as HTTP2 frames.
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type controlBuffer struct {
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ch chan struct{}
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done <-chan struct{}
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mu sync.Mutex
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consumerWaiting bool
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list *itemList
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err error
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}
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func newControlBuffer(done <-chan struct{}) *controlBuffer {
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return &controlBuffer{
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ch: make(chan struct{}, 1),
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list: &itemList{},
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done: done,
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}
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}
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func (c *controlBuffer) put(it interface{}) error {
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_, err := c.executeAndPut(nil, it)
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return err
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}
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func (c *controlBuffer) executeAndPut(f func(it interface{}) bool, it interface{}) (bool, error) {
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var wakeUp bool
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c.mu.Lock()
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if c.err != nil {
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c.mu.Unlock()
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return false, c.err
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}
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if f != nil {
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if !f(it) { // f wasn't successful
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c.mu.Unlock()
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return false, nil
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}
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}
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if c.consumerWaiting {
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wakeUp = true
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c.consumerWaiting = false
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}
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c.list.enqueue(it)
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c.mu.Unlock()
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if wakeUp {
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select {
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case c.ch <- struct{}{}:
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default:
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}
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}
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return true, nil
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}
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// Note argument f should never be nil.
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func (c *controlBuffer) execute(f func(it interface{}) bool, it interface{}) (bool, error) {
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c.mu.Lock()
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if c.err != nil {
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c.mu.Unlock()
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return false, c.err
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}
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if !f(it) { // f wasn't successful
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c.mu.Unlock()
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return false, nil
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}
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c.mu.Unlock()
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return true, nil
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}
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func (c *controlBuffer) get(block bool) (interface{}, error) {
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for {
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c.mu.Lock()
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if c.err != nil {
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c.mu.Unlock()
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return nil, c.err
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}
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if !c.list.isEmpty() {
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h := c.list.dequeue()
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c.mu.Unlock()
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return h, nil
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}
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if !block {
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c.mu.Unlock()
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return nil, nil
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}
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c.consumerWaiting = true
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c.mu.Unlock()
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select {
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case <-c.ch:
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case <-c.done:
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c.finish()
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return nil, ErrConnClosing
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}
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}
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}
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func (c *controlBuffer) finish() {
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c.mu.Lock()
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if c.err != nil {
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c.mu.Unlock()
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return
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}
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c.err = ErrConnClosing
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// There may be headers for streams in the control buffer.
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// These streams need to be cleaned out since the transport
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// is still not aware of these yet.
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for head := c.list.dequeueAll(); head != nil; head = head.next {
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hdr, ok := head.it.(*headerFrame)
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if !ok {
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continue
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}
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if hdr.onOrphaned != nil { // It will be nil on the server-side.
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hdr.onOrphaned(ErrConnClosing)
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}
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}
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c.mu.Unlock()
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}
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type side int
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const (
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clientSide side = iota
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serverSide
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)
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// Loopy receives frames from the control buffer.
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// Each frame is handled individually; most of the work done by loopy goes
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// into handling data frames. Loopy maintains a queue of active streams, and each
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// stream maintains a queue of data frames; as loopy receives data frames
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// it gets added to the queue of the relevant stream.
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// Loopy goes over this list of active streams by processing one node every iteration,
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// thereby closely resemebling to a round-robin scheduling over all streams. While
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// processing a stream, loopy writes out data bytes from this stream capped by the min
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// of http2MaxFrameLen, connection-level flow control and stream-level flow control.
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type loopyWriter struct {
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side side
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cbuf *controlBuffer
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sendQuota uint32
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oiws uint32 // outbound initial window size.
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// estdStreams is map of all established streams that are not cleaned-up yet.
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// On client-side, this is all streams whose headers were sent out.
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// On server-side, this is all streams whose headers were received.
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estdStreams map[uint32]*outStream // Established streams.
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// activeStreams is a linked-list of all streams that have data to send and some
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// stream-level flow control quota.
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// Each of these streams internally have a list of data items(and perhaps trailers
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// on the server-side) to be sent out.
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activeStreams *outStreamList
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framer *framer
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hBuf *bytes.Buffer // The buffer for HPACK encoding.
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hEnc *hpack.Encoder // HPACK encoder.
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bdpEst *bdpEstimator
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draining bool
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// Side-specific handlers
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ssGoAwayHandler func(*goAway) (bool, error)
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}
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func newLoopyWriter(s side, fr *framer, cbuf *controlBuffer, bdpEst *bdpEstimator) *loopyWriter {
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var buf bytes.Buffer
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l := &loopyWriter{
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side: s,
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cbuf: cbuf,
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sendQuota: defaultWindowSize,
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oiws: defaultWindowSize,
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estdStreams: make(map[uint32]*outStream),
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activeStreams: newOutStreamList(),
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framer: fr,
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hBuf: &buf,
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hEnc: hpack.NewEncoder(&buf),
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bdpEst: bdpEst,
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}
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return l
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}
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const minBatchSize = 1000
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// run should be run in a separate goroutine.
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// It reads control frames from controlBuf and processes them by:
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// 1. Updating loopy's internal state, or/and
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// 2. Writing out HTTP2 frames on the wire.
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//
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// Loopy keeps all active streams with data to send in a linked-list.
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// All streams in the activeStreams linked-list must have both:
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// 1. Data to send, and
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// 2. Stream level flow control quota available.
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//
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// In each iteration of run loop, other than processing the incoming control
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// frame, loopy calls processData, which processes one node from the activeStreams linked-list.
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// This results in writing of HTTP2 frames into an underlying write buffer.
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// When there's no more control frames to read from controlBuf, loopy flushes the write buffer.
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// As an optimization, to increase the batch size for each flush, loopy yields the processor, once
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// if the batch size is too low to give stream goroutines a chance to fill it up.
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func (l *loopyWriter) run() (err error) {
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defer func() {
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if err == ErrConnClosing {
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// Don't log ErrConnClosing as error since it happens
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// 1. When the connection is closed by some other known issue.
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// 2. User closed the connection.
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// 3. A graceful close of connection.
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infof("transport: loopyWriter.run returning. %v", err)
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err = nil
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}
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}()
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for {
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it, err := l.cbuf.get(true)
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if err != nil {
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return err
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}
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if err = l.handle(it); err != nil {
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return err
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}
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if _, err = l.processData(); err != nil {
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return err
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}
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gosched := true
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hasdata:
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for {
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it, err := l.cbuf.get(false)
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if err != nil {
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return err
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}
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if it != nil {
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if err = l.handle(it); err != nil {
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return err
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}
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if _, err = l.processData(); err != nil {
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return err
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}
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continue hasdata
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}
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isEmpty, err := l.processData()
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if err != nil {
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return err
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}
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if !isEmpty {
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continue hasdata
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}
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if gosched {
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gosched = false
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if l.framer.writer.offset < minBatchSize {
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runtime.Gosched()
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continue hasdata
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}
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}
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l.framer.writer.Flush()
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break hasdata
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}
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}
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}
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func (l *loopyWriter) outgoingWindowUpdateHandler(w *outgoingWindowUpdate) error {
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return l.framer.fr.WriteWindowUpdate(w.streamID, w.increment)
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}
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func (l *loopyWriter) incomingWindowUpdateHandler(w *incomingWindowUpdate) error {
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// Otherwise update the quota.
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if w.streamID == 0 {
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l.sendQuota += w.increment
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return nil
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}
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// Find the stream and update it.
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if str, ok := l.estdStreams[w.streamID]; ok {
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str.bytesOutStanding -= int(w.increment)
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if strQuota := int(l.oiws) - str.bytesOutStanding; strQuota > 0 && str.state == waitingOnStreamQuota {
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str.state = active
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l.activeStreams.enqueue(str)
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return nil
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}
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}
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return nil
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}
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func (l *loopyWriter) outgoingSettingsHandler(s *outgoingSettings) error {
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return l.framer.fr.WriteSettings(s.ss...)
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}
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func (l *loopyWriter) incomingSettingsHandler(s *incomingSettings) error {
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if err := l.applySettings(s.ss); err != nil {
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return err
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}
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return l.framer.fr.WriteSettingsAck()
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}
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func (l *loopyWriter) registerStreamHandler(h *registerStream) error {
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str := &outStream{
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id: h.streamID,
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state: empty,
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itl: &itemList{},
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wq: h.wq,
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}
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l.estdStreams[h.streamID] = str
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return nil
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}
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func (l *loopyWriter) headerHandler(h *headerFrame) error {
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if l.side == serverSide {
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str, ok := l.estdStreams[h.streamID]
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if !ok {
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warningf("transport: loopy doesn't recognize the stream: %d", h.streamID)
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return nil
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}
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// Case 1.A: Server is responding back with headers.
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if !h.endStream {
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return l.writeHeader(h.streamID, h.endStream, h.hf, h.onWrite)
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}
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// else: Case 1.B: Server wants to close stream.
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if str.state != empty { // either active or waiting on stream quota.
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// add it str's list of items.
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str.itl.enqueue(h)
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return nil
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}
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if err := l.writeHeader(h.streamID, h.endStream, h.hf, h.onWrite); err != nil {
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return err
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}
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return l.cleanupStreamHandler(h.cleanup)
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}
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// Case 2: Client wants to originate stream.
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str := &outStream{
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id: h.streamID,
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state: empty,
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itl: &itemList{},
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wq: h.wq,
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}
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str.itl.enqueue(h)
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return l.originateStream(str)
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}
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func (l *loopyWriter) originateStream(str *outStream) error {
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hdr := str.itl.dequeue().(*headerFrame)
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sendPing, err := hdr.initStream(str.id)
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if err != nil {
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if err == ErrConnClosing {
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return err
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}
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// Other errors(errStreamDrain) need not close transport.
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return nil
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}
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if err = l.writeHeader(str.id, hdr.endStream, hdr.hf, hdr.onWrite); err != nil {
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return err
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}
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l.estdStreams[str.id] = str
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if sendPing {
|
|
return l.pingHandler(&ping{data: [8]byte{}})
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *loopyWriter) writeHeader(streamID uint32, endStream bool, hf []hpack.HeaderField, onWrite func()) error {
|
|
if onWrite != nil {
|
|
onWrite()
|
|
}
|
|
l.hBuf.Reset()
|
|
for _, f := range hf {
|
|
if err := l.hEnc.WriteField(f); err != nil {
|
|
warningf("transport: loopyWriter.writeHeader encountered error while encoding headers:", err)
|
|
}
|
|
}
|
|
var (
|
|
err error
|
|
endHeaders, first bool
|
|
)
|
|
first = true
|
|
for !endHeaders {
|
|
size := l.hBuf.Len()
|
|
if size > http2MaxFrameLen {
|
|
size = http2MaxFrameLen
|
|
} else {
|
|
endHeaders = true
|
|
}
|
|
if first {
|
|
first = false
|
|
err = l.framer.fr.WriteHeaders(http2.HeadersFrameParam{
|
|
StreamID: streamID,
|
|
BlockFragment: l.hBuf.Next(size),
|
|
EndStream: endStream,
|
|
EndHeaders: endHeaders,
|
|
})
|
|
} else {
|
|
err = l.framer.fr.WriteContinuation(
|
|
streamID,
|
|
endHeaders,
|
|
l.hBuf.Next(size),
|
|
)
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *loopyWriter) preprocessData(df *dataFrame) error {
|
|
str, ok := l.estdStreams[df.streamID]
|
|
if !ok {
|
|
return nil
|
|
}
|
|
// If we got data for a stream it means that
|
|
// stream was originated and the headers were sent out.
|
|
str.itl.enqueue(df)
|
|
if str.state == empty {
|
|
str.state = active
|
|
l.activeStreams.enqueue(str)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *loopyWriter) pingHandler(p *ping) error {
|
|
if !p.ack {
|
|
l.bdpEst.timesnap(p.data)
|
|
}
|
|
return l.framer.fr.WritePing(p.ack, p.data)
|
|
|
|
}
|
|
|
|
func (l *loopyWriter) outFlowControlSizeRequestHandler(o *outFlowControlSizeRequest) error {
|
|
o.resp <- l.sendQuota
|
|
return nil
|
|
}
|
|
|
|
func (l *loopyWriter) cleanupStreamHandler(c *cleanupStream) error {
|
|
c.onWrite()
|
|
if str, ok := l.estdStreams[c.streamID]; ok {
|
|
// On the server side it could be a trailers-only response or
|
|
// a RST_STREAM before stream initialization thus the stream might
|
|
// not be established yet.
|
|
delete(l.estdStreams, c.streamID)
|
|
str.deleteSelf()
|
|
}
|
|
if c.rst { // If RST_STREAM needs to be sent.
|
|
if err := l.framer.fr.WriteRSTStream(c.streamID, c.rstCode); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
if l.side == clientSide && l.draining && len(l.estdStreams) == 0 {
|
|
return ErrConnClosing
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *loopyWriter) incomingGoAwayHandler(*incomingGoAway) error {
|
|
if l.side == clientSide {
|
|
l.draining = true
|
|
if len(l.estdStreams) == 0 {
|
|
return ErrConnClosing
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *loopyWriter) goAwayHandler(g *goAway) error {
|
|
// Handling of outgoing GoAway is very specific to side.
|
|
if l.ssGoAwayHandler != nil {
|
|
draining, err := l.ssGoAwayHandler(g)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
l.draining = draining
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *loopyWriter) handle(i interface{}) error {
|
|
switch i := i.(type) {
|
|
case *incomingWindowUpdate:
|
|
return l.incomingWindowUpdateHandler(i)
|
|
case *outgoingWindowUpdate:
|
|
return l.outgoingWindowUpdateHandler(i)
|
|
case *incomingSettings:
|
|
return l.incomingSettingsHandler(i)
|
|
case *outgoingSettings:
|
|
return l.outgoingSettingsHandler(i)
|
|
case *headerFrame:
|
|
return l.headerHandler(i)
|
|
case *registerStream:
|
|
return l.registerStreamHandler(i)
|
|
case *cleanupStream:
|
|
return l.cleanupStreamHandler(i)
|
|
case *incomingGoAway:
|
|
return l.incomingGoAwayHandler(i)
|
|
case *dataFrame:
|
|
return l.preprocessData(i)
|
|
case *ping:
|
|
return l.pingHandler(i)
|
|
case *goAway:
|
|
return l.goAwayHandler(i)
|
|
case *outFlowControlSizeRequest:
|
|
return l.outFlowControlSizeRequestHandler(i)
|
|
default:
|
|
return fmt.Errorf("transport: unknown control message type %T", i)
|
|
}
|
|
}
|
|
|
|
func (l *loopyWriter) applySettings(ss []http2.Setting) error {
|
|
for _, s := range ss {
|
|
switch s.ID {
|
|
case http2.SettingInitialWindowSize:
|
|
o := l.oiws
|
|
l.oiws = s.Val
|
|
if o < l.oiws {
|
|
// If the new limit is greater make all depleted streams active.
|
|
for _, stream := range l.estdStreams {
|
|
if stream.state == waitingOnStreamQuota {
|
|
stream.state = active
|
|
l.activeStreams.enqueue(stream)
|
|
}
|
|
}
|
|
}
|
|
case http2.SettingHeaderTableSize:
|
|
updateHeaderTblSize(l.hEnc, s.Val)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// processData removes the first stream from active streams, writes out at most 16KB
|
|
// of its data and then puts it at the end of activeStreams if there's still more data
|
|
// to be sent and stream has some stream-level flow control.
|
|
func (l *loopyWriter) processData() (bool, error) {
|
|
if l.sendQuota == 0 {
|
|
return true, nil
|
|
}
|
|
str := l.activeStreams.dequeue() // Remove the first stream.
|
|
if str == nil {
|
|
return true, nil
|
|
}
|
|
dataItem := str.itl.peek().(*dataFrame) // Peek at the first data item this stream.
|
|
// A data item is represented by a dataFrame, since it later translates into
|
|
// multiple HTTP2 data frames.
|
|
// Every dataFrame has two buffers; h that keeps grpc-message header and d that is acutal data.
|
|
// As an optimization to keep wire traffic low, data from d is copied to h to make as big as the
|
|
// maximum possilbe HTTP2 frame size.
|
|
|
|
if len(dataItem.h) == 0 && len(dataItem.d) == 0 { // Empty data frame
|
|
// Client sends out empty data frame with endStream = true
|
|
if err := l.framer.fr.WriteData(dataItem.streamID, dataItem.endStream, nil); err != nil {
|
|
return false, err
|
|
}
|
|
str.itl.dequeue() // remove the empty data item from stream
|
|
if str.itl.isEmpty() {
|
|
str.state = empty
|
|
} else if trailer, ok := str.itl.peek().(*headerFrame); ok { // the next item is trailers.
|
|
if err := l.writeHeader(trailer.streamID, trailer.endStream, trailer.hf, trailer.onWrite); err != nil {
|
|
return false, err
|
|
}
|
|
if err := l.cleanupStreamHandler(trailer.cleanup); err != nil {
|
|
return false, nil
|
|
}
|
|
} else {
|
|
l.activeStreams.enqueue(str)
|
|
}
|
|
return false, nil
|
|
}
|
|
var (
|
|
idx int
|
|
buf []byte
|
|
)
|
|
if len(dataItem.h) != 0 { // data header has not been written out yet.
|
|
buf = dataItem.h
|
|
} else {
|
|
idx = 1
|
|
buf = dataItem.d
|
|
}
|
|
size := http2MaxFrameLen
|
|
if len(buf) < size {
|
|
size = len(buf)
|
|
}
|
|
if strQuota := int(l.oiws) - str.bytesOutStanding; strQuota <= 0 { // stream-level flow control.
|
|
str.state = waitingOnStreamQuota
|
|
return false, nil
|
|
} else if strQuota < size {
|
|
size = strQuota
|
|
}
|
|
|
|
if l.sendQuota < uint32(size) { // connection-level flow control.
|
|
size = int(l.sendQuota)
|
|
}
|
|
// Now that outgoing flow controls are checked we can replenish str's write quota
|
|
str.wq.replenish(size)
|
|
var endStream bool
|
|
// If this is the last data message on this stream and all of it can be written in this iteration.
|
|
if dataItem.endStream && size == len(buf) {
|
|
// buf contains either data or it contains header but data is empty.
|
|
if idx == 1 || len(dataItem.d) == 0 {
|
|
endStream = true
|
|
}
|
|
}
|
|
if dataItem.onEachWrite != nil {
|
|
dataItem.onEachWrite()
|
|
}
|
|
if err := l.framer.fr.WriteData(dataItem.streamID, endStream, buf[:size]); err != nil {
|
|
return false, err
|
|
}
|
|
buf = buf[size:]
|
|
str.bytesOutStanding += size
|
|
l.sendQuota -= uint32(size)
|
|
if idx == 0 {
|
|
dataItem.h = buf
|
|
} else {
|
|
dataItem.d = buf
|
|
}
|
|
|
|
if len(dataItem.h) == 0 && len(dataItem.d) == 0 { // All the data from that message was written out.
|
|
str.itl.dequeue()
|
|
}
|
|
if str.itl.isEmpty() {
|
|
str.state = empty
|
|
} else if trailer, ok := str.itl.peek().(*headerFrame); ok { // The next item is trailers.
|
|
if err := l.writeHeader(trailer.streamID, trailer.endStream, trailer.hf, trailer.onWrite); err != nil {
|
|
return false, err
|
|
}
|
|
if err := l.cleanupStreamHandler(trailer.cleanup); err != nil {
|
|
return false, err
|
|
}
|
|
} else if int(l.oiws)-str.bytesOutStanding <= 0 { // Ran out of stream quota.
|
|
str.state = waitingOnStreamQuota
|
|
} else { // Otherwise add it back to the list of active streams.
|
|
l.activeStreams.enqueue(str)
|
|
}
|
|
return false, nil
|
|
}
|