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//
// Copyright (c) 2017 anygone contributors (see AUTHORS file)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * Neither the name of anygone nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
package satp
import (
"errors"
"sync"
)
type SequenceWindow struct {
size int
head uint64
body []uint32
mtx *sync.RWMutex
}
func (w *SequenceWindow) Size() int {
return w.size
}
func (w *SequenceWindow) Top() uint32 {
w.mtx.RLock()
defer w.mtx.RUnlock()
// return uint32(atomic.LoadUint64(&w.head) >> 32)
return uint32(w.head >> 32)
}
func (w *SequenceWindow) Check(sequenceNumber uint32) (bool, error) {
if w.size <= 0 {
return false, nil
}
w.mtx.RLock()
defer w.mtx.RUnlock()
// TODO: implement this
return false, nil
}
func (w *SequenceWindow) CheckAndSet(sequenceNumber uint32) (bool, error) {
if w.size <= 0 {
return false, nil
}
w.mtx.Lock()
defer w.mtx.Unlock()
// TODO: implement this
return false, nil
}
func NewSequenceWindow(size int, top uint32) (w *SequenceWindow, err error) {
if size < 0 {
return nil, errors.New("invalid sequence window size")
}
w = &SequenceWindow{size: size, head: uint64(top) << 32, mtx: &sync.RWMutex{}}
if w.size > 0 {
bodyLen := w.size / 32
if (w.size % 32) != 0 {
bodyLen++
}
w.body = make([]uint32, bodyLen, bodyLen)
remain := uint(top % 32)
for i := uint(0); i < remain; i++ {
w.head |= 1 << i
}
for i := range w.body {
w.body[i] = 0xFFFFFFFF
}
}
return
}
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