diff options
Diffstat (limited to 'kube2msb/src/vendor/golang.org/x/net/http2/writesched.go')
-rw-r--r-- | kube2msb/src/vendor/golang.org/x/net/http2/writesched.go | 283 |
1 files changed, 0 insertions, 283 deletions
diff --git a/kube2msb/src/vendor/golang.org/x/net/http2/writesched.go b/kube2msb/src/vendor/golang.org/x/net/http2/writesched.go deleted file mode 100644 index c24316c..0000000 --- a/kube2msb/src/vendor/golang.org/x/net/http2/writesched.go +++ /dev/null @@ -1,283 +0,0 @@ -// 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" - -// frameWriteMsg is a request to write a frame. -type frameWriteMsg struct { - // write is the interface value that does the writing, once the - // writeScheduler (below) has decided to select this frame - // to write. The write functions are all defined in write.go. - write writeFramer - - stream *stream // used for prioritization. nil for non-stream frames. - - // 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 -} - -// for debugging only: -func (wm frameWriteMsg) String() string { - var streamID uint32 - if wm.stream != nil { - streamID = wm.stream.id - } - var des string - if s, ok := wm.write.(fmt.Stringer); ok { - des = s.String() - } else { - des = fmt.Sprintf("%T", wm.write) - } - return fmt.Sprintf("[frameWriteMsg stream=%d, ch=%v, type: %v]", streamID, wm.done != nil, des) -} - -// writeScheduler tracks pending frames to write, priorities, and decides -// the next one to use. It is not thread-safe. -type writeScheduler struct { - // zero are frames not associated with a specific stream. - // They're sent before any stream-specific freams. - zero writeQueue - - // maxFrameSize is the maximum size of a DATA frame - // we'll write. Must be non-zero and between 16K-16M. - maxFrameSize uint32 - - // sq contains the stream-specific queues, keyed by stream ID. - // when a stream is idle, it's deleted from the map. - sq map[uint32]*writeQueue - - // canSend is a slice of memory that's reused between frame - // scheduling decisions to hold the list of writeQueues (from sq) - // which have enough flow control data to send. After canSend is - // built, the best is selected. - canSend []*writeQueue - - // pool of empty queues for reuse. - queuePool []*writeQueue -} - -func (ws *writeScheduler) putEmptyQueue(q *writeQueue) { - if len(q.s) != 0 { - panic("queue must be empty") - } - ws.queuePool = append(ws.queuePool, q) -} - -func (ws *writeScheduler) getEmptyQueue() *writeQueue { - ln := len(ws.queuePool) - if ln == 0 { - return new(writeQueue) - } - q := ws.queuePool[ln-1] - ws.queuePool = ws.queuePool[:ln-1] - return q -} - -func (ws *writeScheduler) empty() bool { return ws.zero.empty() && len(ws.sq) == 0 } - -func (ws *writeScheduler) add(wm frameWriteMsg) { - st := wm.stream - if st == nil { - ws.zero.push(wm) - } else { - ws.streamQueue(st.id).push(wm) - } -} - -func (ws *writeScheduler) streamQueue(streamID uint32) *writeQueue { - if q, ok := ws.sq[streamID]; ok { - return q - } - if ws.sq == nil { - ws.sq = make(map[uint32]*writeQueue) - } - q := ws.getEmptyQueue() - ws.sq[streamID] = q - return q -} - -// take returns the most important frame to write and removes it from the scheduler. -// It is illegal to call this if the scheduler is empty or if there are no connection-level -// flow control bytes available. -func (ws *writeScheduler) take() (wm frameWriteMsg, ok bool) { - if ws.maxFrameSize == 0 { - panic("internal error: ws.maxFrameSize not initialized or invalid") - } - - // If there any frames not associated with streams, prefer those first. - // These are usually SETTINGS, etc. - if !ws.zero.empty() { - return ws.zero.shift(), true - } - if len(ws.sq) == 0 { - return - } - - // Next, prioritize frames on streams that aren't DATA frames (no cost). - for id, q := range ws.sq { - if q.firstIsNoCost() { - return ws.takeFrom(id, q) - } - } - - // Now, all that remains are DATA frames with non-zero bytes to - // send. So pick the best one. - if len(ws.canSend) != 0 { - panic("should be empty") - } - for _, q := range ws.sq { - if n := ws.streamWritableBytes(q); n > 0 { - ws.canSend = append(ws.canSend, q) - } - } - if len(ws.canSend) == 0 { - return - } - defer ws.zeroCanSend() - - // TODO: find the best queue - q := ws.canSend[0] - - return ws.takeFrom(q.streamID(), q) -} - -// zeroCanSend is defered from take. -func (ws *writeScheduler) zeroCanSend() { - for i := range ws.canSend { - ws.canSend[i] = nil - } - ws.canSend = ws.canSend[:0] -} - -// streamWritableBytes returns the number of DATA bytes we could write -// from the given queue's stream, if this stream/queue were -// selected. It is an error to call this if q's head isn't a -// *writeData. -func (ws *writeScheduler) streamWritableBytes(q *writeQueue) int32 { - wm := q.head() - ret := wm.stream.flow.available() // max we can write - if ret == 0 { - return 0 - } - if int32(ws.maxFrameSize) < ret { - ret = int32(ws.maxFrameSize) - } - if ret == 0 { - panic("internal error: ws.maxFrameSize not initialized or invalid") - } - wd := wm.write.(*writeData) - if len(wd.p) < int(ret) { - ret = int32(len(wd.p)) - } - return ret -} - -func (ws *writeScheduler) takeFrom(id uint32, q *writeQueue) (wm frameWriteMsg, ok bool) { - wm = q.head() - // If the first item in this queue costs flow control tokens - // and we don't have enough, write as much as we can. - if wd, ok := wm.write.(*writeData); ok && len(wd.p) > 0 { - allowed := wm.stream.flow.available() // max we can write - if allowed == 0 { - // No quota available. Caller can try the next stream. - return frameWriteMsg{}, false - } - if int32(ws.maxFrameSize) < allowed { - allowed = int32(ws.maxFrameSize) - } - // TODO: further restrict the allowed size, because even if - // the peer says it's okay to write 16MB data frames, we might - // want to write smaller ones to properly weight competing - // streams' priorities. - - if len(wd.p) > int(allowed) { - wm.stream.flow.take(allowed) - chunk := wd.p[:allowed] - wd.p = wd.p[allowed:] - // Make up a new write message of a valid size, rather - // than shifting one off the queue. - return frameWriteMsg{ - stream: wm.stream, - write: &writeData{ - streamID: wd.streamID, - p: chunk, - // even if the original had endStream set, there - // arebytes remaining because len(wd.p) > allowed, - // so we know endStream is false: - endStream: false, - }, - // our caller is blocking on the final DATA frame, not - // these intermediates, so no need to wait: - done: nil, - }, true - } - wm.stream.flow.take(int32(len(wd.p))) - } - - q.shift() - if q.empty() { - ws.putEmptyQueue(q) - delete(ws.sq, id) - } - return wm, true -} - -func (ws *writeScheduler) forgetStream(id uint32) { - q, ok := ws.sq[id] - if !ok { - return - } - delete(ws.sq, id) - - // But keep it for others later. - for i := range q.s { - q.s[i] = frameWriteMsg{} - } - q.s = q.s[:0] - ws.putEmptyQueue(q) -} - -type writeQueue struct { - s []frameWriteMsg -} - -// streamID returns the stream ID for a non-empty stream-specific queue. -func (q *writeQueue) streamID() uint32 { return q.s[0].stream.id } - -func (q *writeQueue) empty() bool { return len(q.s) == 0 } - -func (q *writeQueue) push(wm frameWriteMsg) { - q.s = append(q.s, wm) -} - -// head returns the next item that would be removed by shift. -func (q *writeQueue) head() frameWriteMsg { - if len(q.s) == 0 { - panic("invalid use of queue") - } - return q.s[0] -} - -func (q *writeQueue) shift() frameWriteMsg { - if len(q.s) == 0 { - panic("invalid use of queue") - } - wm := q.s[0] - // TODO: less copy-happy queue. - copy(q.s, q.s[1:]) - q.s[len(q.s)-1] = frameWriteMsg{} - q.s = q.s[:len(q.s)-1] - return wm -} - -func (q *writeQueue) firstIsNoCost() bool { - if df, ok := q.s[0].write.(*writeData); ok { - return len(df.p) == 0 - } - return true -} |