113 lines
2.5 KiB
Go
113 lines
2.5 KiB
Go
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// +build go1.1
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package quantile_test
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import (
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"bufio"
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"fmt"
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"github.com/bmizerany/perks/quantile"
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"log"
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"os"
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"strconv"
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"time"
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)
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func Example_simple() {
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ch := make(chan float64)
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go sendFloats(ch)
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// Compute the 50th, 90th, and 99th percentile.
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q := quantile.NewTargeted(0.50, 0.90, 0.99)
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for v := range ch {
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q.Insert(v)
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}
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fmt.Println("perc50:", q.Query(0.50))
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fmt.Println("perc90:", q.Query(0.90))
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fmt.Println("perc99:", q.Query(0.99))
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fmt.Println("count:", q.Count())
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// Output:
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// perc50: 5
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// perc90: 14
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// perc99: 40
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// count: 2388
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}
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func Example_mergeMultipleStreams() {
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// Scenario:
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// We have multiple database shards. On each shard, there is a process
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// collecting query response times from the database logs and inserting
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// them into a Stream (created via NewTargeted(0.90)), much like the
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// Simple example. These processes expose a network interface for us to
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// ask them to serialize and send us the results of their
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// Stream.Samples so we may Merge and Query them.
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//
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// NOTES:
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// * These sample sets are small, allowing us to get them
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// across the network much faster than sending the entire list of data
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// points.
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//
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// * For this to work correctly, we must supply the same quantiles
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// a priori the process collecting the samples supplied to NewTargeted,
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// even if we do not plan to query them all here.
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ch := make(chan quantile.Samples)
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getDBQuerySamples(ch)
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q := quantile.NewTargeted(0.90)
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for samples := range ch {
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q.Merge(samples)
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}
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fmt.Println("perc90:", q.Query(0.90))
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}
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func Example_window() {
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// Scenario: We want the 90th, 95th, and 99th percentiles for each
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// minute.
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ch := make(chan float64)
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go sendStreamValues(ch)
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tick := time.NewTicker(1 * time.Minute)
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q := quantile.NewTargeted(0.90, 0.95, 0.99)
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for {
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select {
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case t := <-tick.C:
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flushToDB(t, q.Samples())
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q.Reset()
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case v := <-ch:
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q.Insert(v)
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}
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}
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}
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func sendStreamValues(ch chan float64) {
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// Use your imagination
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}
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func flushToDB(t time.Time, samples quantile.Samples) {
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// Use your imagination
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}
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// This is a stub for the above example. In reality this would hit the remote
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// servers via http or something like it.
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func getDBQuerySamples(ch chan quantile.Samples) {}
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func sendFloats(ch chan<- float64) {
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f, err := os.Open("exampledata.txt")
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if err != nil {
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log.Fatal(err)
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}
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sc := bufio.NewScanner(f)
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for sc.Scan() {
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b := sc.Bytes()
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v, err := strconv.ParseFloat(string(b), 64)
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if err != nil {
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log.Fatal(err)
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}
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ch <- v
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}
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if sc.Err() != nil {
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log.Fatal(sc.Err())
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}
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close(ch)
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}
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