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diff --git a/vendor/golang.org/x/net/http2/writesched.go b/vendor/golang.org/x/net/http2/writesched.go
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+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package http2
+
+import "fmt"
+
+// WriteScheduler is the interface implemented by HTTP/2 write schedulers.
+// Methods are never called concurrently.
+type WriteScheduler interface {
+ // OpenStream opens a new stream in the write scheduler.
+ // It is illegal to call this with streamID=0 or with a streamID that is
+ // already open -- the call may panic.
+ OpenStream(streamID uint32, options OpenStreamOptions)
+
+ // CloseStream closes a stream in the write scheduler. Any frames queued on
+ // this stream should be discarded. It is illegal to call this on a stream
+ // that is not open -- the call may panic.
+ CloseStream(streamID uint32)
+
+ // AdjustStream adjusts the priority of the given stream. This may be called
+ // on a stream that has not yet been opened or has been closed. Note that
+ // RFC 7540 allows PRIORITY frames to be sent on streams in any state. See:
+ // https://tools.ietf.org/html/rfc7540#section-5.1
+ AdjustStream(streamID uint32, priority PriorityParam)
+
+ // Push queues a frame in the scheduler. In most cases, this will not be
+ // called with wr.StreamID()!=0 unless that stream is currently open. The one
+ // exception is RST_STREAM frames, which may be sent on idle or closed streams.
+ Push(wr FrameWriteRequest)
+
+ // Pop dequeues the next frame to write. Returns false if no frames can
+ // be written. Frames with a given wr.StreamID() are Pop'd in the same
+ // order they are Push'd.
+ Pop() (wr FrameWriteRequest, ok bool)
+}
+
+// OpenStreamOptions specifies extra options for WriteScheduler.OpenStream.
+type OpenStreamOptions struct {
+ // PusherID is zero if the stream was initiated by the client. Otherwise,
+ // PusherID names the stream that pushed the newly opened stream.
+ PusherID uint32
+}
+
+// FrameWriteRequest is a request to write a frame.
+type FrameWriteRequest struct {
+ // write is the interface value that does the writing, once the
+ // WriteScheduler has selected this frame to write. The write
+ // functions are all defined in write.go.
+ write writeFramer
+
+ // stream is the stream on which this frame will be written.
+ // nil for non-stream frames like PING and SETTINGS.
+ stream *stream
+
+ // done, if non-nil, must be a buffered channel with space for
+ // 1 message and is sent the return value from write (or an
+ // earlier error) when the frame has been written.
+ done chan error
+}
+
+// StreamID returns the id of the stream this frame will be written to.
+// 0 is used for non-stream frames such as PING and SETTINGS.
+func (wr FrameWriteRequest) StreamID() uint32 {
+ if wr.stream == nil {
+ if se, ok := wr.write.(StreamError); ok {
+ // (*serverConn).resetStream doesn't set
+ // stream because it doesn't necessarily have
+ // one. So special case this type of write
+ // message.
+ return se.StreamID
+ }
+ return 0
+ }
+ return wr.stream.id
+}
+
+// DataSize returns the number of flow control bytes that must be consumed
+// to write this entire frame. This is 0 for non-DATA frames.
+func (wr FrameWriteRequest) DataSize() int {
+ if wd, ok := wr.write.(*writeData); ok {
+ return len(wd.p)
+ }
+ return 0
+}
+
+// Consume consumes min(n, available) bytes from this frame, where available
+// is the number of flow control bytes available on the stream. Consume returns
+// 0, 1, or 2 frames, where the integer return value gives the number of frames
+// returned.
+//
+// If flow control prevents consuming any bytes, this returns (_, _, 0). If
+// the entire frame was consumed, this returns (wr, _, 1). Otherwise, this
+// returns (consumed, rest, 2), where 'consumed' contains the consumed bytes and
+// 'rest' contains the remaining bytes. The consumed bytes are deducted from the
+// underlying stream's flow control budget.
+func (wr FrameWriteRequest) Consume(n int32) (FrameWriteRequest, FrameWriteRequest, int) {
+ var empty FrameWriteRequest
+
+ // Non-DATA frames are always consumed whole.
+ wd, ok := wr.write.(*writeData)
+ if !ok || len(wd.p) == 0 {
+ return wr, empty, 1
+ }
+
+ // Might need to split after applying limits.
+ allowed := wr.stream.flow.available()
+ if n < allowed {
+ allowed = n
+ }
+ if wr.stream.sc.maxFrameSize < allowed {
+ allowed = wr.stream.sc.maxFrameSize
+ }
+ if allowed <= 0 {
+ return empty, empty, 0
+ }
+ if len(wd.p) > int(allowed) {
+ wr.stream.flow.take(allowed)
+ consumed := FrameWriteRequest{
+ stream: wr.stream,
+ write: &writeData{
+ streamID: wd.streamID,
+ p: wd.p[:allowed],
+ // Even if the original had endStream set, there
+ // are bytes remaining because len(wd.p) > allowed,
+ // so we know endStream is false.
+ endStream: false,
+ },
+ // Our caller is blocking on the final DATA frame, not
+ // this intermediate frame, so no need to wait.
+ done: nil,
+ }
+ rest := FrameWriteRequest{
+ stream: wr.stream,
+ write: &writeData{
+ streamID: wd.streamID,
+ p: wd.p[allowed:],
+ endStream: wd.endStream,
+ },
+ done: wr.done,
+ }
+ return consumed, rest, 2
+ }
+
+ // The frame is consumed whole.
+ // NB: This cast cannot overflow because allowed is <= math.MaxInt32.
+ wr.stream.flow.take(int32(len(wd.p)))
+ return wr, empty, 1
+}
+
+// String is for debugging only.
+func (wr FrameWriteRequest) String() string {
+ var des string
+ if s, ok := wr.write.(fmt.Stringer); ok {
+ des = s.String()
+ } else {
+ des = fmt.Sprintf("%T", wr.write)
+ }
+ return fmt.Sprintf("[FrameWriteRequest stream=%d, ch=%v, writer=%v]", wr.StreamID(), wr.done != nil, des)
+}
+
+// replyToWriter sends err to wr.done and panics if the send must block
+// This does nothing if wr.done is nil.
+func (wr *FrameWriteRequest) replyToWriter(err error) {
+ if wr.done == nil {
+ return
+ }
+ select {
+ case wr.done <- err:
+ default:
+ panic(fmt.Sprintf("unbuffered done channel passed in for type %T", wr.write))
+ }
+ wr.write = nil // prevent use (assume it's tainted after wr.done send)
+}
+
+// writeQueue is used by implementations of WriteScheduler.
+type writeQueue struct {
+ s []FrameWriteRequest
+}
+
+func (q *writeQueue) empty() bool { return len(q.s) == 0 }
+
+func (q *writeQueue) push(wr FrameWriteRequest) {
+ q.s = append(q.s, wr)
+}
+
+func (q *writeQueue) shift() FrameWriteRequest {
+ if len(q.s) == 0 {
+ panic("invalid use of queue")
+ }
+ wr := q.s[0]
+ // TODO: less copy-happy queue.
+ copy(q.s, q.s[1:])
+ q.s[len(q.s)-1] = FrameWriteRequest{}
+ q.s = q.s[:len(q.s)-1]
+ return wr
+}
+
+// consume consumes up to n bytes from q.s[0]. If the frame is
+// entirely consumed, it is removed from the queue. If the frame
+// is partially consumed, the frame is kept with the consumed
+// bytes removed. Returns true iff any bytes were consumed.
+func (q *writeQueue) consume(n int32) (FrameWriteRequest, bool) {
+ if len(q.s) == 0 {
+ return FrameWriteRequest{}, false
+ }
+ consumed, rest, numresult := q.s[0].Consume(n)
+ switch numresult {
+ case 0:
+ return FrameWriteRequest{}, false
+ case 1:
+ q.shift()
+ case 2:
+ q.s[0] = rest
+ }
+ return consumed, true
+}
+
+type writeQueuePool []*writeQueue
+
+// put inserts an unused writeQueue into the pool.
+func (p *writeQueuePool) put(q *writeQueue) {
+ for i := range q.s {
+ q.s[i] = FrameWriteRequest{}
+ }
+ q.s = q.s[:0]
+ *p = append(*p, q)
+}
+
+// get returns an empty writeQueue.
+func (p *writeQueuePool) get() *writeQueue {
+ ln := len(*p)
+ if ln == 0 {
+ return new(writeQueue)
+ }
+ x := ln - 1
+ q := (*p)[x]
+ (*p)[x] = nil
+ *p = (*p)[:x]
+ return q
+}