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// +build go1.1
package quantile_test
import (
"bufio"
"fmt"
"log"
"os"
"strconv"
"time"
"github.com/beorn7/perks/quantile"
)
func Example_simple() {
ch := make(chan float64)
go sendFloats(ch)
// Compute the 50th, 90th, and 99th percentile.
q := quantile.NewTargeted(map[float64]float64{
0.50: 0.005,
0.90: 0.001,
0.99: 0.0001,
})
for v := range ch {
q.Insert(v)
}
fmt.Println("perc50:", q.Query(0.50))
fmt.Println("perc90:", q.Query(0.90))
fmt.Println("perc99:", q.Query(0.99))
fmt.Println("count:", q.Count())
// Output:
// perc50: 5
// perc90: 16
// perc99: 223
// count: 2388
}
func Example_mergeMultipleStreams() {
// Scenario:
// We have multiple database shards. On each shard, there is a process
// collecting query response times from the database logs and inserting
// them into a Stream (created via NewTargeted(0.90)), much like the
// Simple example. These processes expose a network interface for us to
// ask them to serialize and send us the results of their
// Stream.Samples so we may Merge and Query them.
//
// NOTES:
// * These sample sets are small, allowing us to get them
// across the network much faster than sending the entire list of data
// points.
//
// * For this to work correctly, we must supply the same quantiles
// a priori the process collecting the samples supplied to NewTargeted,
// even if we do not plan to query them all here.
ch := make(chan quantile.Samples)
getDBQuerySamples(ch)
q := quantile.NewTargeted(map[float64]float64{0.90: 0.001})
for samples := range ch {
q.Merge(samples)
}
fmt.Println("perc90:", q.Query(0.90))
}
func Example_window() {
// Scenario: We want the 90th, 95th, and 99th percentiles for each
// minute.
ch := make(chan float64)
go sendStreamValues(ch)
tick := time.NewTicker(1 * time.Minute)
q := quantile.NewTargeted(map[float64]float64{
0.90: 0.001,
0.95: 0.0005,
0.99: 0.0001,
})
for {
select {
case t := <-tick.C:
flushToDB(t, q.Samples())
q.Reset()
case v := <-ch:
q.Insert(v)
}
}
}
func sendStreamValues(ch chan float64) {
// Use your imagination
}
func flushToDB(t time.Time, samples quantile.Samples) {
// Use your imagination
}
// This is a stub for the above example. In reality this would hit the remote
// servers via http or something like it.
func getDBQuerySamples(ch chan quantile.Samples) {}
func sendFloats(ch chan<- float64) {
f, err := os.Open("exampledata.txt")
if err != nil {
log.Fatal(err)
}
sc := bufio.NewScanner(f)
for sc.Scan() {
b := sc.Bytes()
v, err := strconv.ParseFloat(string(b), 64)
if err != nil {
log.Fatal(err)
}
ch <- v
}
if sc.Err() != nil {
log.Fatal(sc.Err())
}
close(ch)
}
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