Revert "Improving Performance on the API Gzip Handler (#12363)"

This reverts commit dfae954dc1.

Signed-off-by: Julien Pivotto <roidelapluie@o11y.eu>

go.mod

@@ -34,7 +34,6 @@ require (
 	github.com/hetznercloud/hcloud-go v1.45.1
 	github.com/ionos-cloud/sdk-go/v6 v6.1.7
 	github.com/json-iterator/go v1.1.12
-	github.com/klauspost/compress v1.16.5
 	github.com/kolo/xmlrpc v0.0.0-20220921171641-a4b6fa1dd06b
 	github.com/linode/linodego v1.17.0
 	github.com/miekg/dns v1.1.54

go.sum

@@ -507,8 +507,6 @@ github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvW
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/compress v1.13.6/go.mod h1:/3/Vjq9QcHkK5uEr5lBEmyoZ1iFhe47etQ6QUkpK6sk=
-github.com/klauspost/compress v1.16.5 h1:IFV2oUNUzZaz+XyusxpLzpzS8Pt5rh0Z16For/djlyI=
-github.com/klauspost/compress v1.16.5/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
 github.com/kolo/xmlrpc v0.0.0-20220921171641-a4b6fa1dd06b h1:udzkj9S/zlT5X367kqJis0QP7YMxobob6zhzq6Yre00=
 github.com/kolo/xmlrpc v0.0.0-20220921171641-a4b6fa1dd06b/go.mod h1:pcaDhQK0/NJZEvtCO0qQPPropqV0sJOJ6YW7X+9kRwM=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=

util/httputil/compression.go

@@ -14,11 +14,11 @@
 package httputil
 
 import (
+	"compress/gzip"
+	"compress/zlib"
+	"io"
 	"net/http"
 	"strings"
-
-	"github.com/klauspost/compress/gzhttp"
-	"github.com/klauspost/compress/zlib"
 )
 
 const (
@@ -28,27 +28,53 @@ const (
 	deflateEncoding       = "deflate"
 )
 
-// Wrapper around http.ResponseWriter which adds deflate compression
-type deflatedResponseWriter struct {
+// Wrapper around http.Handler which adds suitable response compression based
+// on the client's Accept-Encoding headers.
+type compressedResponseWriter struct {
 	http.ResponseWriter
-	writer *zlib.Writer
+	writer io.Writer
 }
 
 // Writes HTTP response content data.
-func (c *deflatedResponseWriter) Write(p []byte) (int, error) {
+func (c *compressedResponseWriter) Write(p []byte) (int, error) {
 	return c.writer.Write(p)
 }
 
-// Close Closes the deflatedResponseWriter and ensures to flush all data before.
-func (c *deflatedResponseWriter) Close() {
-	c.writer.Close()
+// Closes the compressedResponseWriter and ensures to flush all data before.
+func (c *compressedResponseWriter) Close() {
+	if zlibWriter, ok := c.writer.(*zlib.Writer); ok {
+		zlibWriter.Flush()
+	}
+	if gzipWriter, ok := c.writer.(*gzip.Writer); ok {
+		gzipWriter.Flush()
+	}
+	if closer, ok := c.writer.(io.Closer); ok {
+		defer closer.Close()
+	}
 }
 
-// Constructs a new deflatedResponseWriter to compress the original writer using 'deflate' compression.
-func newDeflateResponseWriter(writer http.ResponseWriter) *deflatedResponseWriter {
-	return &deflatedResponseWriter{
+// Constructs a new compressedResponseWriter based on client request headers.
+func newCompressedResponseWriter(writer http.ResponseWriter, req *http.Request) *compressedResponseWriter {
+	encodings := strings.Split(req.Header.Get(acceptEncodingHeader), ",")
+	for _, encoding := range encodings {
+		switch strings.TrimSpace(encoding) {
+		case gzipEncoding:
+			writer.Header().Set(contentEncodingHeader, gzipEncoding)
+			return &compressedResponseWriter{
+				ResponseWriter: writer,
+				writer:         gzip.NewWriter(writer),
+			}
+		case deflateEncoding:
+			writer.Header().Set(contentEncodingHeader, deflateEncoding)
+			return &compressedResponseWriter{
+				ResponseWriter: writer,
+				writer:         zlib.NewWriter(writer),
+			}
+		}
+	}
+	return &compressedResponseWriter{
 		ResponseWriter: writer,
-		writer:         zlib.NewWriter(writer),
+		writer:         writer,
 	}
 }
 
@@ -60,21 +86,7 @@ type CompressionHandler struct {
 
 // ServeHTTP adds compression to the original http.Handler's ServeHTTP() method.
 func (c CompressionHandler) ServeHTTP(writer http.ResponseWriter, req *http.Request) {
-	encodings := strings.Split(req.Header.Get(acceptEncodingHeader), ",")
-	for _, encoding := range encodings {
-		switch strings.TrimSpace(encoding) {
-		case gzipEncoding:
-			gzhttp.GzipHandler(c.Handler).ServeHTTP(writer, req)
-			return
-		case deflateEncoding:
-			compWriter := newDeflateResponseWriter(writer)
-			writer.Header().Set(contentEncodingHeader, deflateEncoding)
-			c.Handler.ServeHTTP(compWriter, req)
-			compWriter.Close()
-			return
-		default:
-			c.Handler.ServeHTTP(writer, req)
-			return
-		}
-	}
+	compWriter := newCompressedResponseWriter(writer, req)
+	c.Handler.ServeHTTP(compWriter, req)
+	compWriter.Close()
 }

util/httputil/compression_test.go

@@ -17,30 +17,23 @@ import (
 	"bytes"
 	"compress/gzip"
 	"compress/zlib"
-	"encoding/json"
-	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
-	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
-
-	"github.com/prometheus/prometheus/model/labels"
 )
 
 var (
-	mux      *http.ServeMux
-	server   *httptest.Server
-	respBody = strings.Repeat("Hello World!", 500)
+	mux    *http.ServeMux
+	server *httptest.Server
 )
 
 func setup() func() {
 	mux = http.NewServeMux()
 	server = httptest.NewServer(mux)
 	return func() {
-		server.CloseClientConnections()
 		server.Close()
 	}
 }
@@ -48,7 +41,7 @@ func setup() func() {
 func getCompressionHandlerFunc() CompressionHandler {
 	hf := func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusOK)
-		w.Write([]byte(respBody))
+		w.Write([]byte("Hello World!"))
 	}
 	return CompressionHandler{
 		Handler: http.HandlerFunc(hf),
@@ -74,8 +67,9 @@ func TestCompressionHandler_PlainText(t *testing.T) {
 	contents, err := io.ReadAll(resp.Body)
 	require.NoError(t, err, "unexpected error while creating the response body reader")
 
+	expected := "Hello World!"
 	actual := string(contents)
-	require.Equal(t, respBody, actual, "expected response with content")
+	require.Equal(t, expected, actual, "expected response with content")
 }
 
 func TestCompressionHandler_Gzip(t *testing.T) {
@@ -109,7 +103,8 @@ func TestCompressionHandler_Gzip(t *testing.T) {
 	require.NoError(t, err, "unexpected error while reading the response body")
 
 	actual := buf.String()
-	require.Equal(t, respBody, actual, "unexpected response content")
+	expected := "Hello World!"
+	require.Equal(t, expected, actual, "unexpected response content")
 }
 
 func TestCompressionHandler_Deflate(t *testing.T) {
@@ -143,98 +138,6 @@ func TestCompressionHandler_Deflate(t *testing.T) {
 	require.NoError(t, err, "unexpected error while reading the response body")
 
 	actual := buf.String()
-	require.Equal(t, respBody, actual, "expected response with content")
-}
-
-func Benchmark_compression(b *testing.B) {
-	client := &http.Client{
-		Transport: &http.Transport{
-			DisableCompression: true,
-		},
-	}
-
-	cases := map[string]struct {
-		enc            string
-		numberOfLabels int
-	}{
-		"gzip-10-labels": {
-			enc:            gzipEncoding,
-			numberOfLabels: 10,
-		},
-		"gzip-100-labels": {
-			enc:            gzipEncoding,
-			numberOfLabels: 100,
-		},
-		"gzip-1K-labels": {
-			enc:            gzipEncoding,
-			numberOfLabels: 1000,
-		},
-		"gzip-10K-labels": {
-			enc:            gzipEncoding,
-			numberOfLabels: 10000,
-		},
-		"gzip-100K-labels": {
-			enc:            gzipEncoding,
-			numberOfLabels: 100000,
-		},
-		"gzip-1M-labels": {
-			enc:            gzipEncoding,
-			numberOfLabels: 1000000,
-		},
-	}
-
-	for name, tc := range cases {
-		b.Run(name, func(b *testing.B) {
-			tearDown := setup()
-			defer tearDown()
-			labels := labels.ScratchBuilder{}
-
-			for i := 0; i < tc.numberOfLabels; i++ {
-				labels.Add(fmt.Sprintf("Name%v", i), fmt.Sprintf("Value%v", i))
-			}
-
-			respBody, err := json.Marshal(labels.Labels())
-			require.NoError(b, err)
-
-			hf := func(w http.ResponseWriter, r *http.Request) {
-				w.WriteHeader(http.StatusOK)
-				w.Write(respBody)
-			}
-			h := CompressionHandler{
-				Handler: http.HandlerFunc(hf),
-			}
-
-			mux.Handle("/foo_endpoint", h)
-
-			req, _ := http.NewRequest("GET", server.URL+"/foo_endpoint", nil)
-			req.Header.Set(acceptEncodingHeader, tc.enc)
-
-			b.ReportAllocs()
-			b.ResetTimer()
-
-			// Reusing the array to read the body and avoid allocation on the test
-			encRespBody := make([]byte, len(respBody))
-
-			for i := 0; i < b.N; i++ {
-				resp, err := client.Do(req)
-
-				require.NoError(b, err)
-
-				require.NoError(b, err, "client get failed with unexpected error")
-				responseBodySize := 0
-				for {
-					n, err := resp.Body.Read(encRespBody)
-					responseBodySize += n
-					if err == io.EOF {
-						break
-					}
-				}
-
-				b.ReportMetric(float64(responseBodySize), "ContentLength")
-				resp.Body.Close()
-			}
-
-			client.CloseIdleConnections()
-		})
-	}
+	expected := "Hello World!"
+	require.Equal(t, expected, actual, "expected response with content")
 }