51 lines
957 B
Go
51 lines
957 B
Go
// Copyright (C) 2018 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package model
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import "sync"
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type byteSemaphore struct {
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max int
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available int
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mut sync.Mutex
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cond *sync.Cond
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}
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func newByteSemaphore(max int) *byteSemaphore {
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s := byteSemaphore{
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max: max,
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available: max,
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}
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s.cond = sync.NewCond(&s.mut)
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return &s
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}
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func (s *byteSemaphore) take(bytes int) {
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if bytes > s.max {
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bytes = s.max
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}
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s.mut.Lock()
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for bytes > s.available {
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s.cond.Wait()
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}
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s.available -= bytes
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s.mut.Unlock()
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}
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func (s *byteSemaphore) give(bytes int) {
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if bytes > s.max {
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bytes = s.max
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}
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s.mut.Lock()
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if s.available+bytes > s.max {
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panic("bug: can never give more than max")
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}
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s.available += bytes
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s.cond.Broadcast()
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s.mut.Unlock()
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}
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