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103 lines
2.3 KiB
Go
103 lines
2.3 KiB
Go
// Package estimator implements a packet and byte rate estimator.
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package estimator
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import (
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"sync"
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"time"
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"github.com/jech/galene/rtptime"
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)
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type Estimator struct {
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interval uint64
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mu sync.Mutex
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time uint64
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bytes uint32
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packets uint32
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totalBytes uint64
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totalPackets uint64
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rate uint32
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packetRate uint32
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}
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// New creates a new estimator that estimates rate over the last interval.
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func New(interval time.Duration) *Estimator {
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return new(rtptime.Now(rtptime.JiffiesPerSec), interval)
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}
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func new(now uint64, interval time.Duration) *Estimator {
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return &Estimator{
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interval: uint64(
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rtptime.FromDuration(interval, rtptime.JiffiesPerSec),
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),
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time: now,
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}
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}
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// called locked
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func (e *Estimator) swap(now uint64) {
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jiffies := now - e.time
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bytes := e.bytes
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e.bytes = 0
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packets := e.packets
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e.packets = 0
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e.totalBytes += uint64(bytes)
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e.totalPackets += uint64(packets)
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var rate, packetRate uint32
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if jiffies >= rtptime.JiffiesPerSec/1000 {
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rate = uint32((uint64(bytes)*rtptime.JiffiesPerSec + jiffies/2) / jiffies)
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packetRate = uint32((uint64(packets)*rtptime.JiffiesPerSec + jiffies/2) / jiffies)
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}
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e.rate = rate
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e.packetRate = packetRate
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e.time = now
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}
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// Accumulate records one packet of size bytes
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func (e *Estimator) Accumulate(bytes uint32) {
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e.mu.Lock()
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if e.bytes < ^uint32(0)-bytes {
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e.bytes += bytes
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}
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if e.packets < ^uint32(0)-1 {
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e.packets += 1
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}
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e.mu.Unlock()
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}
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// called locked
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func (e *Estimator) estimate(now uint64) (uint32, uint32) {
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if now < e.time {
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// time went backwards
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if e.time-now > e.interval {
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e.time = now
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e.packets = 0
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e.bytes = 0
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}
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} else if now-e.time >= e.interval {
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e.swap(now)
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}
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return e.rate, e.packetRate
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}
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// Estimate returns an estimate of the rate over the last interval.
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// It starts a new interval if the last interval is larger than the value
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// passed to New. It returns the byte rate and the packet rate, in units
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// per second.
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func (e *Estimator) Estimate() (uint32, uint32) {
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e.mu.Lock()
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defer e.mu.Unlock()
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return e.estimate(rtptime.Now(rtptime.JiffiesPerSec))
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}
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// Totals returns the total number of bytes and packets accumulated.
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func (e *Estimator) Totals() (uint64, uint64) {
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e.mu.Lock()
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defer e.mu.Unlock()
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return e.totalPackets + uint64(e.packets),
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e.totalBytes + uint64(e.bytes)
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}
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