mirror of
https://github.com/ceph/ceph-csi.git
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73 lines
1.9 KiB
Go
73 lines
1.9 KiB
Go
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/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package buffer
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// RingGrowing is a growing ring buffer.
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// Not thread safe.
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type RingGrowing struct {
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data []interface{}
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n int // Size of Data
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beg int // First available element
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readable int // Number of data items available
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}
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// NewRingGrowing constructs a new RingGrowing instance with provided parameters.
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func NewRingGrowing(initialSize int) *RingGrowing {
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return &RingGrowing{
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data: make([]interface{}, initialSize),
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n: initialSize,
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}
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}
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// ReadOne reads (consumes) first item from the buffer if it is available, otherwise returns false.
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func (r *RingGrowing) ReadOne() (data interface{}, ok bool) {
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if r.readable == 0 {
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return nil, false
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}
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r.readable--
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element := r.data[r.beg]
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r.data[r.beg] = nil // Remove reference to the object to help GC
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if r.beg == r.n-1 {
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// Was the last element
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r.beg = 0
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} else {
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r.beg++
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}
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return element, true
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}
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// WriteOne adds an item to the end of the buffer, growing it if it is full.
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func (r *RingGrowing) WriteOne(data interface{}) {
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if r.readable == r.n {
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// Time to grow
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newN := r.n * 2
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newData := make([]interface{}, newN)
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to := r.beg + r.readable
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if to <= r.n {
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copy(newData, r.data[r.beg:to])
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} else {
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copied := copy(newData, r.data[r.beg:])
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copy(newData[copied:], r.data[:(to%r.n)])
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}
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r.beg = 0
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r.data = newData
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r.n = newN
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}
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r.data[(r.readable+r.beg)%r.n] = data
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r.readable++
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}
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