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5b53aa1108
Wiser coders than myself have come to the conclusion that a `switch` statement is almost always superior to a statement that includes any `else if`. The exceptions that I have found in our codebase are just these two: * The `if else` is followed by an additional statement before the next condition (separated by a `;`). * The whole thing is within a `for` loop and `break` statements are used. In this case, using `switch` would require tagging the `for` loop, which probably tips the balance. Why are `switch` statements more readable? For one, fewer curly braces. But more importantly, the conditions all have the same alignment, so the whole thing follows the natural flow of going down a list of conditions. With `else if`, in contrast, all conditions but the first are "hidden" behind `} else if `, harder to spot and (for no good reason) presented differently from the first condition. I'm sure the aforemention wise coders can list even more reasons. In any case, I like it so much that I have found myself recommending it in code reviews. I would like to make it a habit in our code base, without making it a hard requirement that we would test on the CI. But for that, there has to be a role model, so this commit eliminates all `if else` occurrences, unless it is autogenerated code or fits one of the exceptions above. Signed-off-by: beorn7 <beorn@grafana.com>
71 lines
1.7 KiB
Go
71 lines
1.7 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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"time"
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"go.uber.org/atomic"
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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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newEvents atomic.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 := r.newEvents.Swap(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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switch {
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case r.init:
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r.lastRate += r.alpha * (instantRate - r.lastRate)
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case 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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r.newEvents.Add(incr)
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}
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