mirror of
https://github.com/weaveworks/scope.git
synced 2026-08-18 20:07:06 +00:00
Matthias Radestock
43c84b38e2
for more efficient LatestMap merge Note that all the sorting and ID calculation code in the old SmartMerger was done so we could cache of intermediate results. But we disabled caching some time ago, so there is no point carrying around all the supporting code.
62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
package app
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import (
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"fmt"
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"github.com/spaolacci/murmur3"
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"github.com/weaveworks/scope/report"
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)
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// Merger is the type for a thing that can merge reports.
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type Merger interface {
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Merge([]report.Report) report.Report
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}
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type dumbMerger struct{}
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// MakeDumbMerger makes a Merger which merges together reports in the simplest possible way.
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func MakeDumbMerger() Merger {
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return dumbMerger{}
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}
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func (dumbMerger) Merge(reports []report.Report) report.Report {
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rpt := report.MakeReport()
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id := murmur3.New64()
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for _, r := range reports {
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rpt = rpt.Merge(r)
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id.Write([]byte(r.ID))
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}
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rpt.ID = fmt.Sprintf("%x", id.Sum64())
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return rpt
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}
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type smartMerger struct {
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}
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// NewSmartMerger makes a Merger which merges together reports as
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// a binary tree of reports. Speed up comes from the fact that
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// most merges are between small reports.
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func NewSmartMerger() Merger {
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return smartMerger{}
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}
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// Merge merges the reports as a binary tree. Crucially, it
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// effectively merges reports in reverse order. Typically reports are
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// ordered oldest-to-youngest, so this strategy merges older reports
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// "into" younger reports. This order is more efficient for some Merge
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// operations, in particular LatestMap.Merge.
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func (s smartMerger) Merge(reports []report.Report) report.Report {
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l := len(reports)
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switch l {
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case 0:
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return report.MakeReport()
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case 1:
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return reports[0]
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case 2:
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return reports[1].Merge(reports[0])
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}
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partition := l / 2
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return s.Merge(reports[partition:]).Merge(s.Merge(reports[:partition]))
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}
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