mirror of
https://github.com/gravitational/teleport.git
synced 2026-09-21 14:35:22 +08:00
92 lines
2.1 KiB
Go
92 lines
2.1 KiB
Go
/*
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* Teleport
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* Copyright (C) 2023 Gravitational, Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package utils
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import (
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"sync"
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"github.com/gravitational/trace"
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)
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// CircularBuffer implements an in-memory circular buffer of predefined size
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type CircularBuffer struct {
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sync.Mutex
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buf []float64
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start int
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end int
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size int
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}
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// NewCircularBuffer returns a new instance of a circular buffer that will hold
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// size elements before it rotates
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func NewCircularBuffer(size int) (*CircularBuffer, error) {
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if size <= 0 {
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return nil, trace.BadParameter("circular buffer size should be > 0")
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}
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buf := &CircularBuffer{
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buf: make([]float64, size),
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start: -1,
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end: -1,
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size: 0,
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}
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return buf, nil
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}
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// Data returns the most recent n elements in the correct order
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func (t *CircularBuffer) Data(n int) []float64 {
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t.Lock()
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defer t.Unlock()
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if n <= 0 || t.size == 0 {
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return nil
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}
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// skip first N items so that the most recent are always provided
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start := t.start
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if n < t.size {
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start = (t.start + (t.size - n)) % len(t.buf)
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}
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if start <= t.end {
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return t.buf[start : t.end+1]
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}
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return append(t.buf[start:], t.buf[:t.end+1]...)
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}
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// Add pushes a new item onto the buffer
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func (t *CircularBuffer) Add(d float64) {
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t.Lock()
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defer t.Unlock()
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if t.size == 0 {
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t.start = 0
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t.end = 0
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t.size = 1
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} else if t.size < len(t.buf) {
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t.end++
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t.size++
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} else {
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t.end = t.start
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t.start = (t.start + 1) % len(t.buf)
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}
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t.buf[t.end] = d
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}
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