/usr/share/gocode/src/github.com/jacobsa/gcloud/tools/gcs_speed/main.go is in golang-github-jacobsa-gcloud-dev 0.0~git20150709-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// A program that makes random reads within a large object on GCS, reporting
// throughput and latency information.
package main
import (
"errors"
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"math/rand"
"os"
"os/signal"
"sort"
"sync"
"time"
"golang.org/x/net/context"
"golang.org/x/oauth2/google"
"github.com/jacobsa/gcloud/gcs"
"github.com/jacobsa/syncutil"
)
var fBucket = flag.String("bucket", "", "The GCS bucket from which to read.")
var fObject = flag.String("object", "", "The object within which to read.")
var fSize = flag.Uint64("size", 1<<21, "The size of each read in bytes.")
var fWorkers = flag.Int("workers", 1, "The number of workers to run.")
////////////////////////////////////////////////////////////////////////
// Helpers
////////////////////////////////////////////////////////////////////////
type result struct {
BytesRead int
// Time taken from making the HTTP request to receiving the first byte of the
// response body.
FirstByteLatency time.Duration
// Time taken from making the HTTP request to receiving the last byte of the
// response body.
FullBodyDuration time.Duration
}
func readOnce(
ctx context.Context,
o *gcs.Object,
bucket gcs.Bucket) (r result, err error) {
// Is the object large enough?
if o.Size < *fSize {
err = fmt.Errorf(
"Object of size %d not large enough for read size %d",
o.Size,
*fSize)
return
}
// Set up an appropriate request.
req := &gcs.ReadObjectRequest{
Name: o.Name,
Generation: o.Generation,
Range: &gcs.ByteRange{},
}
req.Range.Start = uint64(rand.Int63n(int64(o.Size - *fSize)))
req.Range.Limit = req.Range.Start + *fSize
// Create the reader.
start := time.Now()
rc, err := bucket.NewReader(ctx, req)
if err != nil {
err = fmt.Errorf("NewReader: %v", err)
return
}
defer func() {
closeErr := rc.Close()
if err == nil && closeErr != nil {
err = fmt.Errorf("Close: %v", closeErr)
}
}()
// Measure the time to first byte.
_, err = rc.Read([]byte{0})
if err != nil {
err = fmt.Errorf("Read: %v", err)
return
}
r.FirstByteLatency = time.Since(start)
// And the time to read everything.
n, err := io.Copy(ioutil.Discard, rc)
if err != nil {
err = fmt.Errorf("Copy: %v", err)
return
}
r.FullBodyDuration = time.Since(start)
r.BytesRead = int(n + 1)
return
}
// Make random reads within the given object, writing results to the supplied
// channel. Stop when the stop channel is closed.
func makeReads(
ctx context.Context,
o *gcs.Object,
bucket gcs.Bucket,
results chan<- result,
stop <-chan struct{}) (err error) {
// Is the object large enough?
if o.Size < *fSize {
err = fmt.Errorf(
"Object of size %d not large enough for read size %d",
o.Size,
*fSize)
return
}
for {
// Stop?
select {
case <-stop:
return
default:
}
// Make a read.
var r result
r, err = readOnce(ctx, o, bucket)
if err != nil {
err = fmt.Errorf("readOnce %v", err)
return
}
log.Printf(
"Read %d bytes in %v (first byte latency %v)",
r.BytesRead,
r.FullBodyDuration,
r.FirstByteLatency)
// Write out the result.
select {
case <-ctx.Done():
err = ctx.Err()
return
case results <- r:
}
}
}
func getBucket(ctx context.Context) (b gcs.Bucket, err error) {
if *fBucket == "" {
err = errors.New("You must set --bucket.")
return
}
// Set up the token source.
const scope = gcs.Scope_ReadOnly
tokenSrc, err := google.DefaultTokenSource(context.Background(), scope)
if err != nil {
err = fmt.Errorf("DefaultTokenSource: %v", err)
return
}
// Use that to create a GCS connection.
cfg := &gcs.ConnConfig{
TokenSource: tokenSrc,
}
conn, err := gcs.NewConn(cfg)
if err != nil {
err = fmt.Errorf("NewConn: %v", err)
return
}
// Open the bucket.
b, err = conn.OpenBucket(ctx, *fBucket)
if err != nil {
err = fmt.Errorf("OpenBucket: %v", err)
return
}
return
}
func getObject(
ctx context.Context,
bucket gcs.Bucket) (o *gcs.Object, err error) {
if *fObject == "" {
err = errors.New("You must set --object.")
return
}
o, err = bucket.StatObject(
ctx,
&gcs.StatObjectRequest{Name: *fObject})
return
}
// Run workers until SIGINT is received. Return a slice of results.
func runWorkers(
ctx context.Context,
o *gcs.Object,
bucket gcs.Bucket) (results []result, err error) {
b := syncutil.NewBundle(ctx)
// Set up a channel that is closed upon SIGINT.
stop := make(chan struct{})
go func() {
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
<-c
log.Printf("SIGINT received. Stopping soon...")
close(stop)
}()
// Start several workers making random reads.
var wg sync.WaitGroup
resultChan := make(chan result)
for i := 0; i < *fWorkers; i++ {
wg.Add(1)
b.Add(func(ctx context.Context) (err error) {
defer wg.Done()
err = makeReads(ctx, o, bucket, resultChan, stop)
if err != nil {
err = fmt.Errorf("makeReads: %v", err)
return
}
return
})
}
go func() {
wg.Wait()
close(resultChan)
}()
// Accumulate results.
b.Add(func(ctx context.Context) (err error) {
for r := range resultChan {
results = append(results, r)
}
return
})
err = b.Join()
return
}
// REQUIRES: len(vals) > 0
// REQUIRES: 0 <= n <= 100
func percentile(
vals sort.IntSlice,
n int) (x int) {
// Special cases.
switch {
case n == 0:
x = vals[0]
return
case n == 100:
x = vals[len(vals)-1]
return
}
// Find the nearest, truncating (why not).
index := int((float64(n) / 100) * float64(len(vals)))
x = vals[index]
return
}
func describeResults(results []result) {
fmt.Printf("Made %d reads.\n\n", len(results))
ptiles := []int{0, 50, 95, 99, 100}
// Compute first byte latency percentiles.
var vals sort.IntSlice
for _, r := range results {
vals = append(vals, int(r.FirstByteLatency))
}
sort.Sort(vals)
fmt.Printf("First byte latency stats:\n")
for _, ptile := range ptiles {
fmt.Printf(
" %3d ptile: %v\n", ptile,
time.Duration(percentile(vals, ptile)))
}
// Compute overall duration percentiles.
vals = nil
for _, r := range results {
vals = append(vals, int(r.FullBodyDuration))
}
sort.Sort(vals)
fmt.Printf("\nFull body stats:\n")
for _, ptile := range ptiles {
d := time.Duration(percentile(vals, ptile))
bw := float64(*fSize) / (float64(d) / float64(time.Second))
fmt.Printf(" %3d ptile: %v (%f MB/s)\n", ptile, d, bw/1e6)
}
}
////////////////////////////////////////////////////////////////////////
// Main
////////////////////////////////////////////////////////////////////////
func run(ctx context.Context) (err error) {
// Open the bucket.
bucket, err := getBucket(ctx)
if err != nil {
err = fmt.Errorf("getBucket: %v", err)
return
}
// Stat the object.
o, err := getObject(ctx, bucket)
if err != nil {
err = fmt.Errorf("getObject: %v", err)
return
}
// Make reads.
results, err := runWorkers(ctx, o, bucket)
if err != nil {
err = fmt.Errorf("runWorkers: %v", err)
return
}
// Print information about the results.
describeResults(results)
return
}
func main() {
log.SetFlags(log.Lmicroseconds)
flag.Parse()
err := run(context.Background())
if err != nil {
log.Fatal(err)
}
}
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