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// Copyright (C) 2018 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package model
import (
"sync"
)
type byteSemaphore struct {
max int
available int
mut sync.Mutex
cond *sync.Cond
}
func newByteSemaphore(max int) *byteSemaphore {
s := byteSemaphore{
max: max,
available: max,
}
s.cond = sync.NewCond(&s.mut)
return &s
}
func (s *byteSemaphore) take(bytes int) {
s.mut.Lock()
if bytes > s.max {
bytes = s.max
}
for bytes > s.available {
s.cond.Wait()
if bytes > s.max {
bytes = s.max
}
}
s.available -= bytes
s.mut.Unlock()
}
func (s *byteSemaphore) give(bytes int) {
s.mut.Lock()
if bytes > s.max {
bytes = s.max
}
if s.available+bytes > s.max {
s.available = s.max
} else {
s.available += bytes
}
s.cond.Broadcast()
s.mut.Unlock()
}
func (s *byteSemaphore) setCapacity(cap int) {
s.mut.Lock()
diff := cap - s.max
s.max = cap
s.available += diff
if s.available < 0 {
s.available = 0
} else if s.available > s.max {
s.available = s.max
}
s.cond.Broadcast()
s.mut.Unlock()
}
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