92 lines
2.9 KiB
Go
92 lines
2.9 KiB
Go
/*
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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 util
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// FloatSlidingWindow is a buffer with a fixed capacity. Elements are
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// inserted/removed in the FIFO order. Elements are removed from the buffer
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// only when it runs out of capacity and a new element is inserted.
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type FloatSlidingWindow interface {
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// Add a value to the end of the queue. On overflow returns true and the
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// oldest value, which is also removed from the buffer. Otherwise
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// returns (false, _).
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Push(value float64) (bool, float64)
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// Returns the elements in the buffer, ordered by time of insertion
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// (oldest first).
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Contents() []float64
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// Returns a pointer to the most recently added element. The pointer can
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// be used to modify the last element. It is only valid until the next
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// call to Push(). Return nil if called on an empty buffer.
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Head() *float64
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}
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// NewFloatSlidingWindow returns a new instance of FloatSlidingWindowImpl with a
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// given size.
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func NewFloatSlidingWindow(size int) FloatSlidingWindow {
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if size < 1 {
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panic("Buffer size must be at least 1")
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}
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return &floatSlidingWindow{make([]float64, 0), -1, size, false}
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}
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type floatSlidingWindow struct {
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buffer []float64
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// Index of the most recently added element.
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head int
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// Max number of elements.
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capacity int
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// Whether the buffer is full, i.e. the number of elements in the buffer
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// equals capacity.
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isFull bool
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}
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// Head returns a pointer to the most recently added element. The pointer can be
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// used to modify the last element. It is only valid until the next call to
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// Push(). Returns nil if called on an empty buffer.
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func (b *floatSlidingWindow) Head() *float64 {
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if b.head == -1 {
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return nil
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}
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return &b.buffer[b.head]
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}
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// Contents returns the elements in the buffer, ordered by time of insertion
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// (oldest first).
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func (b *floatSlidingWindow) Contents() []float64 {
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return append(b.buffer[b.head+1:], b.buffer[:b.head+1]...)
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}
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// Push adds a value to the end of the window. On overflow returns true and the
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// oldest value, which is also removed from the window. Otherwise returns
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// (false, _).
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func (b *floatSlidingWindow) Push(value float64) (bool, float64) {
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b.head++
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if b.head == b.capacity {
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b.head = 0
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b.isFull = true
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}
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if !b.isFull {
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b.buffer = append(b.buffer, value)
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return false, 0.0
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}
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// Buffer is full. Rewrite the oldest entry and return it.
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prevValue := b.buffer[b.head]
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b.buffer[b.head] = value
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return true, prevValue
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}
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