Add optimized ReadAll function (elastic#229)

* Add optimized ReadAll function

This adds an optimized io.ReadAll that uses a bytes.Buffer + io.Copy
internally, improving the buffer growth ratio over the runtime append
and taking advange of io.WriterTo when available.

The only scenario where this optimizes version is slower than io.ReadAll is
when reading < 512 bytes of a reader that does not implement io.WriterTo.

For now I only updated tests to use the new function as updating the code
requires more careful consideration.

While at it, migrate from the deprecated ioutil.ReadAll to io.ReadAll.

goos: linux
goarch: amd64
pkg: github.com/elastic/elastic-agent-libs/iobuf
cpu: Intel(R) Xeon(R) CPU E5-2697A v4 @ 2.60GHz
BenchmarkReadAll/size_32B/io.ReadAll/WriterTo-32         	 7479658	       162.4 ns/op	     512 B/op	       1 allocs/op
BenchmarkReadAll/size_32B/io.ReadAll/Reader-32           	 7000012	       169.3 ns/op	     512 B/op	       1 allocs/op
BenchmarkReadAll/size_32B/ReadAll/WriterTo-32            	10630838	       112.3 ns/op	     112 B/op	       2 allocs/op
BenchmarkReadAll/size_32B/ReadAll/Reader-32              	 2111246	       567.3 ns/op	    1584 B/op	       3 allocs/op
BenchmarkReadAll/size_64B/io.ReadAll/WriterTo-32         	 7154652	       163.2 ns/op	     512 B/op	       1 allocs/op
BenchmarkReadAll/size_64B/io.ReadAll/Reader-32           	 7223264	       166.1 ns/op	     512 B/op	       1 allocs/op
BenchmarkReadAll/size_64B/ReadAll/WriterTo-32            	10400562	       113.5 ns/op	     112 B/op	       2 allocs/op
BenchmarkReadAll/size_64B/ReadAll/Reader-32              	 2129949	       558.7 ns/op	    1584 B/op	       3 allocs/op
BenchmarkReadAll/size_512B/io.ReadAll/WriterTo-32        	 2843871	       419.1 ns/op	    1408 B/op	       2 allocs/op
BenchmarkReadAll/size_512B/io.ReadAll/Reader-32          	 2871580	       413.1 ns/op	    1408 B/op	       2 allocs/op
BenchmarkReadAll/size_512B/ReadAll/WriterTo-32           	 4976233	       241.5 ns/op	     560 B/op	       2 allocs/op
BenchmarkReadAll/size_512B/ReadAll/Reader-32             	 2183186	       552.9 ns/op	    1584 B/op	       3 allocs/op
BenchmarkReadAll/size_10KB/io.ReadAll/WriterTo-32        	  142633	      8235 ns/op	   46080 B/op	      10 allocs/op
BenchmarkReadAll/size_10KB/io.ReadAll/Reader-32          	  148326	      8229 ns/op	   46080 B/op	      10 allocs/op
BenchmarkReadAll/size_10KB/ReadAll/WriterTo-32           	  574903	      2210 ns/op	   10288 B/op	       2 allocs/op
BenchmarkReadAll/size_10KB/ReadAll/Reader-32             	  147210	      7995 ns/op	   32304 B/op	       7 allocs/op
BenchmarkReadAll/size_100KB/io.ReadAll/WriterTo-32       	   13171	     90853 ns/op	  514304 B/op	      18 allocs/op
BenchmarkReadAll/size_100KB/io.ReadAll/Reader-32         	   12892	     91787 ns/op	  514304 B/op	      18 allocs/op
BenchmarkReadAll/size_100KB/ReadAll/WriterTo-32          	   51472	     22420 ns/op	  106544 B/op	       2 allocs/op
BenchmarkReadAll/size_100KB/ReadAll/Reader-32            	   21568	     55070 ns/op	  261680 B/op	      10 allocs/op
BenchmarkReadAll/size_1MB/io.ReadAll/WriterTo-32         	    1220	    983276 ns/op	 5241098 B/op	      27 allocs/op
BenchmarkReadAll/size_1MB/io.ReadAll/Reader-32           	    1089	    990818 ns/op	 5241100 B/op	      27 allocs/op
BenchmarkReadAll/size_1MB/ReadAll/WriterTo-32            	    4153	    294507 ns/op	 1048627 B/op	       2 allocs/op
BenchmarkReadAll/size_1MB/ReadAll/Reader-32              	    1195	    944781 ns/op	 4193852 B/op	      14 allocs/op

* check error returned by Seek

* update ReadAll doc

* fix linter error in doc

* nolint for http.Serve

* fix license headers

* fix code duplication

* use t.TempDir instead of os.MkdirTemp

* remove os.CreateTemp

---------

Co-authored-by: Denis <denis@rdner.de>

api/npipe/listener_windows_test.go

@@ -21,10 +21,10 @@ package npipe
 
 import (
 	"fmt"
-	"io/ioutil"
 	"net/http"
 	"testing"
 
+	"github.com/elastic/elastic-agent-libs/transport/httpcommon"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -43,7 +43,8 @@ func TestHTTPOverNamedPipe(t *testing.T) {
 	})
 
 	go func() {
-		_ = http.Serve(l, mux)
+		_ = http.Serve(l, mux) //nolint:gosec // Serve does not support setting timeouts, it is fine for tests.
+
 	}()
 
 	c := http.Client{
@@ -52,10 +53,10 @@ func TestHTTPOverNamedPipe(t *testing.T) {
 		},
 	}
 
-	// nolint:noctx // for testing purposes
+	//nolint:noctx // for testing purposes
 	r, err := c.Get("http://npipe/echo-hello")
 	require.NoError(t, err)
-	body, err := ioutil.ReadAll(r.Body)
+	body, err := httpcommon.ReadAll(r)
 	require.NoError(t, err)
 	defer r.Body.Close()
 

api/server_test.go

@@ -20,8 +20,6 @@ package api
 import (
 	"context"
 	"fmt"
-	"io"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"os"
@@ -32,6 +30,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/elastic/elastic-agent-libs/config"
+	"github.com/elastic/elastic-agent-libs/transport/httpcommon"
 )
 
 const (
@@ -71,10 +70,7 @@ func TestSocket(t *testing.T) {
 	}
 
 	t.Run("socket doesn't exist before", func(t *testing.T) {
-		tmpDir, err := ioutil.TempDir("", "testsocket")
-		require.NoError(t, err)
-		defer os.RemoveAll(tmpDir)
-
+		tmpDir := t.TempDir()
 		sockFile := tmpDir + "/test.sock"
 
 		cfg := config.MustNewConfigFrom(map[string]interface{}{
@@ -102,11 +98,7 @@ func TestSocket(t *testing.T) {
 	})
 
 	t.Run("starting beat and recover a dangling socket file", func(t *testing.T) {
-		tmpDir, err := ioutil.TempDir("", "testsocket")
-		require.NoError(t, err)
-		defer os.RemoveAll(tmpDir)
-
-		sockFile := tmpDir + "/test.sock"
+		sockFile := t.TempDir() + "/test.sock"
 
 		// Create the socket before the server.
 		f, err := os.Create(sockFile)
@@ -161,7 +153,7 @@ func getResponse(t *testing.T, sockFile, url string) string {
 	require.NoError(t, err)
 	defer r.Body.Close()
 
-	body, err := ioutil.ReadAll(r.Body)
+	body, err := httpcommon.ReadAll(r)
 	require.NoError(t, err)
 	return string(body)
 }
@@ -188,7 +180,7 @@ func TestHTTP(t *testing.T) {
 		require.NoError(t, err)
 	}()
 
-	body, err := ioutil.ReadAll(r.Body)
+	body, err := httpcommon.ReadAll(r)
 	require.NoError(t, err)
 
 	assert.Equal(t, "ehlo!", string(body))
@@ -229,7 +221,7 @@ func TestAttachHandler(t *testing.T) {
 		require.NoError(t, err)
 	}()
 
-	body, err := io.ReadAll(r.Body)
+	body, err := httpcommon.ReadAll(r)
 	require.NoError(t, err)
 
 	assert.Equal(t, "test!", string(body))

api/server_windows_test.go

@@ -20,7 +20,6 @@
 package api
 
 import (
-	"io/ioutil"
 	"net/http"
 	"testing"
 
@@ -29,6 +28,7 @@ import (
 
 	"github.com/elastic/elastic-agent-libs/api/npipe"
 	"github.com/elastic/elastic-agent-libs/config"
+	"github.com/elastic/elastic-agent-libs/transport/httpcommon"
 )
 
 func TestNamedPipe(t *testing.T) {
@@ -52,12 +52,12 @@ func TestNamedPipe(t *testing.T) {
 		},
 	}
 
-	// nolint:noctx // for testing purposes
+	//nolint:noctx // for testing purposes
 	r, err := c.Get("http://npipe/echo-hello")
 	require.NoError(t, err)
 	defer r.Body.Close()
 
-	body, err := ioutil.ReadAll(r.Body)
+	body, err := httpcommon.ReadAll(r)
 	require.NoError(t, err)
 
 	assert.Equal(t, "ehlo!", string(body))

file/fileinfo_test.go

@@ -24,7 +24,6 @@
 package file_test
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -35,13 +34,14 @@ import (
 )
 
 func TestStat(t *testing.T) {
-	f, err := ioutil.TempFile("", "teststat")
+	tmpDir := t.TempDir()
+	f, err := os.Create(filepath.Join(tmpDir, "teststat"))
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer os.Remove(f.Name())
+	defer f.Close()
 
-	link := filepath.Join(os.TempDir(), "teststat-link")
+	link := filepath.Join(tmpDir, "teststat-link")
 	if err := os.Symlink(f.Name(), link); err != nil {
 		t.Fatal(err)
 	}

file/helper_test.go

@@ -20,7 +20,7 @@
 package file
 
 import (
-	"io/ioutil"
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -29,19 +29,15 @@ import (
 )
 
 func TestSafeFileRotateExistingFile(t *testing.T) {
-	tempdir, err := ioutil.TempDir("", "")
-	assert.NoError(t, err)
-	defer func() {
-		assert.NoError(t, os.RemoveAll(tempdir))
-	}()
+	tempdir := t.TempDir()
 
 	// create an existing registry file
-	err = ioutil.WriteFile(filepath.Join(tempdir, "registry"),
+	err := os.WriteFile(filepath.Join(tempdir, "registry"),
 		[]byte("existing filebeat"), 0x777)
 	assert.NoError(t, err)
 
 	// create a new registry.new file
-	err = ioutil.WriteFile(filepath.Join(tempdir, "registry.new"),
+	err = os.WriteFile(filepath.Join(tempdir, "registry.new"),
 		[]byte("new filebeat"), 0x777)
 	assert.NoError(t, err)
 
@@ -50,35 +46,23 @@ func TestSafeFileRotateExistingFile(t *testing.T) {
 		filepath.Join(tempdir, "registry.new"))
 	assert.NoError(t, err)
 
-	contents, err := ioutil.ReadFile(filepath.Join(tempdir, "registry"))
+	contents, err := os.ReadFile(filepath.Join(tempdir, "registry"))
 	assert.NoError(t, err)
 	assert.Equal(t, []byte("new filebeat"), contents)
 
-	// do it again to make sure we deal with deleting the old file
-
-	err = ioutil.WriteFile(filepath.Join(tempdir, "registry.new"),
-		[]byte("new filebeat 1"), 0x777)
-	assert.NoError(t, err)
-
-	err = SafeFileRotate(filepath.Join(tempdir, "registry"),
-		filepath.Join(tempdir, "registry.new"))
-	assert.NoError(t, err)
-
-	contents, err = ioutil.ReadFile(filepath.Join(tempdir, "registry"))
-	assert.NoError(t, err)
-	assert.Equal(t, []byte("new filebeat 1"), contents)
-
-	// and again for good measure
-
-	err = ioutil.WriteFile(filepath.Join(tempdir, "registry.new"),
-		[]byte("new filebeat 2"), 0x777)
-	assert.NoError(t, err)
-
-	err = SafeFileRotate(filepath.Join(tempdir, "registry"),
-		filepath.Join(tempdir, "registry.new"))
-	assert.NoError(t, err)
-
-	contents, err = ioutil.ReadFile(filepath.Join(tempdir, "registry"))
-	assert.NoError(t, err)
-	assert.Equal(t, []byte("new filebeat 2"), contents)
+	// do it twice to make sure we deal with deleting the old file
+	for i := 0; i < 2; i++ {
+		expectedContents := []byte(fmt.Sprintf("new filebeat %d", i))
+		err = os.WriteFile(filepath.Join(tempdir, "registry.new"),
+			expectedContents, 0x777)
+		assert.NoError(t, err)
+
+		err = SafeFileRotate(filepath.Join(tempdir, "registry"),
+			filepath.Join(tempdir, "registry.new"))
+		assert.NoError(t, err)
+
+		contents, err = os.ReadFile(filepath.Join(tempdir, "registry"))
+		assert.NoError(t, err)
+		assert.Equal(t, expectedContents, contents)
+	}
 }

iobuf/iobuf.go

@@ -0,0 +1,36 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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.
+
+package iobuf
+
+import (
+	"bytes"
+	"io"
+)
+
+// ReadAll reads all data from r and returns it as a byte slice.
+// A successful call returns err == nil, not err == EOF. It does not
+// treat an EOF as an error to be reported.
+//
+// This function is similar to io.ReadAll, but uses a bytes.Buffer to
+// accumulate the data, which has a more efficient growing algorithm and
+// uses io.WriterTo if r implements it.
+func ReadAll(r io.Reader) ([]byte, error) {
+	var buf bytes.Buffer
+	_, err := io.Copy(&buf, r)
+	return buf.Bytes(), err
+}