forked from mirror/client_golang
52 lines
1.4 KiB
Go
52 lines
1.4 KiB
Go
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// Copyright (c) 2012, Matt T. Proud
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// All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// eviction.go provides several histogram bucket eviction strategies.
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package metrics
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import (
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"container/heap"
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"github.com/matttproud/golang_instrumentation/maths"
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"github.com/matttproud/golang_instrumentation/utility"
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"time"
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)
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// EvictionPolicy implements some sort of garbage collection methodology for
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// an underlying heap.Interface. This is presently only used for
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// AccumulatingBucket.
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type EvictionPolicy func(h heap.Interface)
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// As the name implies, this evicts the oldest x objects from the heap.
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func EvictOldest(count int) EvictionPolicy {
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return func(h heap.Interface) {
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for i := 0; i < count; i++ {
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heap.Pop(h)
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}
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}
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}
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// This factory produces an EvictionPolicy that applies some standardized
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// reduction methodology on the to-be-terminated values.
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//
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// TODO(mtp): Parameterize the priority generation since these tools are useful.
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func EvictAndReplaceWith(count int, reducer maths.ReductionMethod) EvictionPolicy {
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return func(h heap.Interface) {
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oldValues := make([]float64, count)
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for i := 0; i < count; i++ {
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oldValues[i] = heap.Pop(h).(*utility.Item).Value.(float64)
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}
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reduced := reducer(oldValues)
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heap.Push(h, &utility.Item{
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Value: reduced,
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Priority: -1 * time.Now().UnixNano(),
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})
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}
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}
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