122 lines
2.7 KiB
Go
122 lines
2.7 KiB
Go
// +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)
|
|
}
|