From 8bb580abfc0eb363d8c4d065f32797d85b88c3a4 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Fri, 5 Feb 2021 09:57:30 -0800
Subject: [PATCH] fix: use getObjectNInfo to avoid bytes.Buffer usage (#11428)

few places were still using legacy call GetObject()
which was mainly designed for client response writer,
use GetObjectNInfo() for internal calls instead.
---
 cmd/config-common.go    | 17 +++++++++++------
 cmd/data-crawler.go     | 12 ++++++++----
 cmd/data-usage.go       |  9 ++++-----
 cmd/metacache-bucket.go | 20 +++++++-------------
 4 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/cmd/config-common.go b/cmd/config-common.go
index c071ba4b0..9a4e82fc3 100644
--- a/cmd/config-common.go
+++ b/cmd/config-common.go
@@ -20,6 +20,8 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"io/ioutil"
+	"net/http"
 
 	"github.com/minio/minio/pkg/hash"
 )
@@ -27,9 +29,9 @@ import (
 var errConfigNotFound = errors.New("config file not found")
 
 func readConfig(ctx context.Context, objAPI ObjectLayer, configFile string) ([]byte, error) {
-	var buffer bytes.Buffer
 	// Read entire content by setting size to -1
-	if err := objAPI.GetObject(ctx, minioMetaBucket, configFile, 0, -1, &buffer, "", ObjectOptions{}); err != nil {
+	r, err := objAPI.GetObjectNInfo(ctx, minioMetaBucket, configFile, nil, http.Header{}, readLock, ObjectOptions{})
+	if err != nil {
 		// Treat object not found as config not found.
 		if isErrObjectNotFound(err) {
 			return nil, errConfigNotFound
@@ -37,13 +39,16 @@ func readConfig(ctx context.Context, objAPI ObjectLayer, configFile string) ([]b
 
 		return nil, err
 	}
+	defer r.Close()
 
-	// Return config not found on empty content.
-	if buffer.Len() == 0 {
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+	if len(buf) == 0 {
 		return nil, errConfigNotFound
 	}
-
-	return buffer.Bytes(), nil
+	return buf, nil
 }
 
 type objectDeleter interface {
diff --git a/cmd/data-crawler.go b/cmd/data-crawler.go
index f4666bafc..8c77c2bed 100644
--- a/cmd/data-crawler.go
+++ b/cmd/data-crawler.go
@@ -23,6 +23,7 @@ import (
 	"errors"
 	"math"
 	"math/rand"
+	"net/http"
 	"os"
 	"path"
 	"strings"
@@ -84,16 +85,19 @@ func runDataCrawler(ctx context.Context, objAPI ObjectLayer) {
 
 	// Load current bloom cycle
 	nextBloomCycle := intDataUpdateTracker.current() + 1
-	var buf bytes.Buffer
-	err := objAPI.GetObject(ctx, dataUsageBucket, dataUsageBloomName, 0, -1, &buf, "", ObjectOptions{})
+
+	br, err := objAPI.GetObjectNInfo(ctx, dataUsageBucket, dataUsageBloomName, nil, http.Header{}, readLock, ObjectOptions{})
 	if err != nil {
 		if !isErrObjectNotFound(err) && !isErrBucketNotFound(err) {
 			logger.LogIf(ctx, err)
 		}
 	} else {
-		if buf.Len() == 8 {
-			nextBloomCycle = binary.LittleEndian.Uint64(buf.Bytes())
+		if br.ObjInfo.Size == 8 {
+			if err = binary.Read(br, binary.LittleEndian, &nextBloomCycle); err != nil {
+				logger.LogIf(ctx, err)
+			}
 		}
+		br.Close()
 	}
 
 	crawlTimer := time.NewTimer(dataCrawlStartDelay)
diff --git a/cmd/data-usage.go b/cmd/data-usage.go
index 87e6e9851..5da9d8394 100644
--- a/cmd/data-usage.go
+++ b/cmd/data-usage.go
@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"net/http"
 
 	jsoniter "github.com/json-iterator/go"
 	"github.com/minio/minio/cmd/logger"
@@ -59,20 +60,18 @@ func storeDataUsageInBackend(ctx context.Context, objAPI ObjectLayer, dui <-chan
 }
 
 func loadDataUsageFromBackend(ctx context.Context, objAPI ObjectLayer) (DataUsageInfo, error) {
-	var dataUsageInfoJSON bytes.Buffer
-
-	err := objAPI.GetObject(ctx, dataUsageBucket, dataUsageObjName, 0, -1, &dataUsageInfoJSON, "", ObjectOptions{})
+	r, err := objAPI.GetObjectNInfo(ctx, dataUsageBucket, dataUsageObjName, nil, http.Header{}, readLock, ObjectOptions{})
 	if err != nil {
 		if isErrObjectNotFound(err) || isErrBucketNotFound(err) {
 			return DataUsageInfo{}, nil
 		}
 		return DataUsageInfo{}, toObjectErr(err, dataUsageBucket, dataUsageObjName)
 	}
+	defer r.Close()
 
 	var dataUsageInfo DataUsageInfo
 	var json = jsoniter.ConfigCompatibleWithStandardLibrary
-	err = json.Unmarshal(dataUsageInfoJSON.Bytes(), &dataUsageInfo)
-	if err != nil {
+	if err = json.NewDecoder(r).Decode(&dataUsageInfo); err != nil {
 		return DataUsageInfo{}, err
 	}
 
diff --git a/cmd/metacache-bucket.go b/cmd/metacache-bucket.go
index fead6473b..1e0aaa5f2 100644
--- a/cmd/metacache-bucket.go
+++ b/cmd/metacache-bucket.go
@@ -21,7 +21,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io"
+	"net/http"
 	"path"
 	"runtime/debug"
 	"strings"
@@ -95,25 +95,19 @@ func loadBucketMetaCache(ctx context.Context, bucket string) (*bucketMetacache,
 			logger.LogIf(ctx, fmt.Errorf("loadBucketMetaCache: object layer not ready. bucket: %q", bucket))
 		}
 	}
+
 	var meta bucketMetacache
 	var decErr error
-	var wg sync.WaitGroup
-	wg.Add(1)
-
-	r, w := io.Pipe()
-	go func() {
-		defer wg.Done()
+	// Use global context for this.
+	r, err := objAPI.GetObjectNInfo(GlobalContext, minioMetaBucket, pathJoin("buckets", bucket, ".metacache", "index.s2"), nil, http.Header{}, readLock, ObjectOptions{})
+	if err == nil {
 		dec := s2DecPool.Get().(*s2.Reader)
 		dec.Reset(r)
 		decErr = meta.DecodeMsg(msgp.NewReader(dec))
 		dec.Reset(nil)
+		r.Close()
 		s2DecPool.Put(dec)
-		r.CloseWithError(decErr)
-	}()
-	// Use global context for this.
-	err := objAPI.GetObject(GlobalContext, minioMetaBucket, pathJoin("buckets", bucket, ".metacache", "index.s2"), 0, -1, w, "", ObjectOptions{})
-	logger.LogIf(ctx, w.CloseWithError(err))
-	wg.Wait()
+	}
 	if err != nil {
 		switch err.(type) {
 		case ObjectNotFound: