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6970f725c9
An extra sync.Pool was added during a refactor which caused some 64 bit, atomically accessed variables to no longer be 64 bit aligned. By moving all atomically accessed variables to the beginning of the struct they are guaranteed to be 64 bit aligned. Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>
71 lines
1.9 KiB
Go
71 lines
1.9 KiB
Go
// Copyright 2013 The Prometheus 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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package remote
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import (
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"sync"
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"sync/atomic"
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"time"
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)
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// ewmaRate tracks an exponentially weighted moving average of a per-second rate.
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type ewmaRate struct {
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// Keep all 64bit atomically accessed variables at the top of this struct.
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// See https://golang.org/pkg/sync/atomic/#pkg-note-BUG for more info.
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newEvents int64
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alpha float64
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interval time.Duration
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lastRate float64
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init bool
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mutex sync.Mutex
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}
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// newEWMARate always allocates a new ewmaRate, as this guarantees the atomically
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// accessed int64 will be aligned on ARM. See prometheus#2666.
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func newEWMARate(alpha float64, interval time.Duration) *ewmaRate {
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return &ewmaRate{
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alpha: alpha,
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interval: interval,
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}
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}
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// rate returns the per-second rate.
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func (r *ewmaRate) rate() float64 {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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return r.lastRate
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}
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// tick assumes to be called every r.interval.
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func (r *ewmaRate) tick() {
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newEvents := atomic.SwapInt64(&r.newEvents, 0)
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instantRate := float64(newEvents) / r.interval.Seconds()
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r.mutex.Lock()
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defer r.mutex.Unlock()
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if r.init {
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r.lastRate += r.alpha * (instantRate - r.lastRate)
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} else if newEvents > 0 {
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r.init = true
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r.lastRate = instantRate
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}
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}
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// inc counts one event.
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func (r *ewmaRate) incr(incr int64) {
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atomic.AddInt64(&r.newEvents, incr)
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}
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