Revert "store: fix marshaling with sync.Pool (thanos-io#4593)"

This reverts commit 8b4c3c9.

Signed-off-by: Giedrius Statkevičius <giedrius.statkevicius@vinted.com>

pkg/store/storepb/custom.go

@@ -497,45 +497,32 @@ func (m *SeriesResponse) Marshal() (dAtA []byte, err error) {
 
 	var respBuf []byte
 
-	// Slow path with no sync.Pool.
+	// No pool defined, allocate directly.
 	if m.respPool == nil {
 		respBuf = make([]byte, size)
-
-		n, err := m.MarshalToSizedBuffer(respBuf)
-		if err != nil {
-			return nil, err
-		}
-		return respBuf[len(respBuf)-n:], nil
-	}
-
-	// Fast path with sync.Pool.
-	// m.respBuf must not be nil so that it would be returned to the pool.
-
-	// If no pre-allocated buffer has been passed then try to get a new one.
-	if m.respBuf == nil {
-		poolBuf := m.respPool.Get()
-		// No previous buffer found in the pool, try to allocate.
-		if poolBuf == nil {
-			respBuf = make([]byte, size)
-		} else {
-			// Found something, let's see if it is big enough.
-			respBuf = *(poolBuf.(*[]byte))
-		}
 	} else {
-		respBuf = *m.respBuf
-	}
-
-	// Last sanity check of the size before the marshaling.
-	if cap(respBuf) < size {
-		if m.respPool != nil {
-			m.respPool.Put(&respBuf)
+		if m.respBuf == nil {
+			poolBuf := m.respPool.Get()
+			if poolBuf == nil {
+				respBuf = make([]byte, size)
+				m.respBuf = &respBuf
+			} else {
+				m.respBuf = poolBuf.(*[]byte)
+				respBuf = *m.respBuf
+			}
+		} else {
+			if cap(*m.respBuf) < size {
+				if m.respPool != nil {
+					m.respPool.Put(m.respBuf)
+				}
+				respBuf = make([]byte, size)
+				m.respBuf = &respBuf
+			} else {
+				respBuf = *m.respBuf
+			}
 		}
-		respBuf = make([]byte, size)
 	}
-	m.respBuf = &respBuf
 
-	// Possibly trim it so that there wouldn't be left-over "garbage" in the slice.
-	// TODO: check if it is needed to always trim this.
 	marshalBuf := respBuf[:size]
 	n, err := m.MarshalToSizedBuffer(marshalBuf)
 	if err != nil {

pkg/store/storepb/custom_test.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"path/filepath"
 	"sort"
-	"sync"
 	"testing"
 
 	"github.com/pkg/errors"
@@ -526,47 +525,3 @@ func TestMatchersToString_Translate(t *testing.T) {
 
 	}
 }
-
-// Tests whether the Marshal() function properly checks the size
-// of a slice returned from a sync.Pool.
-// Regression test against https://github.com/thanos-io/thanos/issues/4591.
-func TestMarshalChecksSize(t *testing.T) {
-	var s Series
-
-	rawData := []rawSeries{
-		{
-			lset: labels.Labels{labels.Label{Name: "a", Value: "c"}},
-			chunks: [][]sample{
-				{{t: 11, v: 11}, {t: 12, v: 12}, {t: 13, v: 13}, {t: 14, v: 14}},
-				{{t: 1, v: 1}, {t: 2, v: 2}, {t: 3, v: 3}, {t: 4, v: 4}},
-				{{t: 20, v: 20}, {t: 21, v: 21}, {t: 22, v: 22}, {t: 24, v: 24}},
-				{{t: 11, v: 11}, {t: 12, v: 12}, {t: 13, v: 13}, {t: 14, v: 14}},
-				{{t: 15, v: 15}, {t: 16, v: 16}, {t: 17, v: 17}, {t: 18, v: 18}},
-				{{t: 20, v: 20}, {t: 21, v: 21}, {t: 22, v: 23}, {t: 24, v: 24}},
-				{{t: 11, v: 11}, {t: 12, v: 12}, {t: 13, v: 13}, {t: 14, v: 14}},
-			},
-		},
-	}
-
-	listSS := newListSeriesSet(t, rawData)
-	lset, chks := listSS.At()
-
-	s.Chunks = chks
-	s.Labels = labelpb.ZLabelsFromPromLabels(lset)
-
-	resp := NewSeriesResponse(&s)
-
-	smallPool := sync.Pool{
-		New: func() interface{} {
-			b := make([]byte, 1)
-			return &b
-		},
-	}
-	resp.respPool = &smallPool
-
-	d, err := resp.Marshal()
-	testutil.Ok(t, err)
-	testutil.Assert(t, d != nil)
-
-	resp.Close()
-}