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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.
// Flow control
package http2
// flow is the flow control window's size.
type flow struct {
// n is the number of DATA bytes we're allowed to send.
// A flow is kept both on a conn and a per-stream.
n int32
// conn points to the shared connection-level flow that is
// shared by all streams on that conn. It is nil for the flow
// that's on the conn directly.
conn *flow
}
func (f *flow) setConnFlow(cf *flow) { f.conn = cf }
func (f *flow) available() int32 {
n := f.n
if f.conn != nil && f.conn.n < n {
n = f.conn.n
}
return n
}
func (f *flow) take(n int32) {
if n > f.available() {
panic("internal error: took too much")
}
f.n -= n
if f.conn != nil {
f.conn.n -= n
}
}
// add adds n bytes (positive or negative) to the flow control window.
// It returns false if the sum would exceed 2^31-1.
func (f *flow) add(n int32) bool {
remain := (1<<31 - 1) - f.n
if n > remain {
return false
}
f.n += n
return true
}
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