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72 lines
1.9 KiB
72 lines
1.9 KiB
/* |
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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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