Parametrize compression level

app/multitenant/aws_collector.go

@@ -2,6 +2,7 @@ package multitenant
 
 import (
 	"bytes"
+	"compress/gzip"
 	"crypto/md5"
 	"fmt"
 	"io"
@@ -346,7 +347,7 @@ func (c *awsCollector) Add(ctx context.Context, rep report.Report) error {
 
 	// first, encode the report into a buffer and record its size
 	var buf bytes.Buffer
-	rep.WriteBinary(&buf)
+	rep.WriteBinary(&buf, gzip.BestCompression)
 	reportSizeHistogram.Observe(float64(buf.Len()))
 
 	// second, put the report on s3

probe/appclient/report_publisher.go

@@ -2,6 +2,7 @@ package appclient
 
 import (
 	"bytes"
+	"compress/gzip"
 	"github.com/weaveworks/scope/report"
 )
 
@@ -28,6 +29,6 @@ func (p *ReportPublisher) Publish(r report.Report) error {
 		})
 	}
 	buf := &bytes.Buffer{}
-	r.WriteBinary(buf)
+	r.WriteBinary(buf, gzip.BestCompression)
 	return p.publisher.Publish(buf)
 }

report/marshal.go

@@ -9,8 +9,8 @@ import (
 )
 
 // WriteBinary writes a Report as a gzipped msgpack.
-func (rep Report) WriteBinary(w io.Writer) error {
-	gzwriter, err := gzip.NewWriterLevel(w, gzip.BestCompression)
+func (rep Report) WriteBinary(w io.Writer, compressionLevel int) error {
+	gzwriter, err := gzip.NewWriterLevel(w, compressionLevel)
 	if err != nil {
 		return err
 	}

report/marshal_test.go

@@ -2,6 +2,7 @@ package report_test
 
 import (
 	"bytes"
+	"compress/gzip"
 	"reflect"
 	"testing"
 
@@ -11,7 +12,7 @@ import (
 func TestRoundtrip(t *testing.T) {
 	var buf bytes.Buffer
 	r1 := report.MakeReport()
-	r1.WriteBinary(&buf)
+	r1.WriteBinary(&buf, gzip.BestCompression)
 	r2, err := report.MakeFromBinary(&buf)
 	if err != nil {
 		t.Error(err)
@@ -20,3 +21,29 @@ func TestRoundtrip(t *testing.T) {
 		t.Errorf("%v != %v", r1, *r2)
 	}
 }
+
+func TestRoundtripNoCompression(t *testing.T) {
+	// Make sure that we can use our standard routines for decompressing
+	// something with '0' level compression.
+	var buf bytes.Buffer
+	r1 := report.MakeReport()
+	r1.WriteBinary(&buf, 0)
+	r2, err := report.MakeFromBinary(&buf)
+	if err != nil {
+		t.Error(err)
+	}
+	if !reflect.DeepEqual(r1, *r2) {
+		t.Errorf("%v != %v", r1, *r2)
+	}
+}
+
+func TestMoreCompressionMeansSmaller(t *testing.T) {
+	// Make sure that 0 level compression actually does compress less.
+	var buf1, buf2 bytes.Buffer
+	r := report.MakeReport()
+	r.WriteBinary(&buf1, gzip.BestCompression)
+	r.WriteBinary(&buf2, 0)
+	if buf1.Len() >= buf2.Len() {
+		t.Errorf("Compression doesn't change size: %v >= %v", buf1.Len(), buf2.Len())
+	}
+}