fix: Export exportTSInSecs field in TSDB identifier to make sure co…

…rrect gap calculation (#13116)

 In summary, the Meta(now in loki/pkg/storage/stores/shipper/bloomshipper/client.go) structure contains a Sources []tsdb.SingleTenantTSDBIdentifier field, and within tsdb.SingleTenantTSDBIdentifier, there is an exportTSInSecs field. When Meta is serialized and written to OSS storage, the exportTSInSecs field is being set to its default value, false, which is not the expected behavior. It should retain its actual value; otherwise, this will lead to issues during subsequent gap calculations.

Co-authored-by: Christian Haudum <christian.haudum@gmail.com>

pkg/storage/stores/shipper/indexshipper/tsdb/identifier.go

@@ -64,11 +64,11 @@ func (p prefixedIdentifier) Name() string {
 // Identifier has all the information needed to resolve a TSDB index
 // Notably this abstracts away OS path separators, etc.
 type SingleTenantTSDBIdentifier struct {
-	// exportTSInSecs tells whether creation timestamp should be exported in unix seconds instead of nanoseconds.
+	// ExportTSInSecs tells whether creation timestamp should be exported in unix seconds instead of nanoseconds.
 	// timestamp in filename could be a unix second or a unix nanosecond so
 	// helps us to be able to reproduce filename back from parsed identifier.
 	// Should be true ideally for older files with creation timestamp in seconds.
-	exportTSInSecs bool
+	ExportTSInSecs bool
 	TS             time.Time
 	From, Through  model.Time
 	Checksum       uint32
@@ -83,7 +83,7 @@ func (i SingleTenantTSDBIdentifier) Hash(h hash.Hash32) (err error) {
 // str builds filename with format <file-creation-ts> + `-` + `compactor` + `-` + <oldest-chunk-start-ts> + `-` + <latest-chunk-end-ts> `-` + <index-checksum>
 func (i SingleTenantTSDBIdentifier) str() string {
 	ts := int64(0)
-	if i.exportTSInSecs {
+	if i.ExportTSInSecs {
 		ts = i.TS.Unix()
 	} else {
 		ts = i.TS.UnixNano()
@@ -151,7 +151,7 @@ func ParseSingleTenantTSDBPath(p string) (id SingleTenantTSDBIdentifier, ok bool
 		parsedTS = time.Unix(0, ts)
 	}
 	return SingleTenantTSDBIdentifier{
-		exportTSInSecs: len(elems[0]) <= 10,
+		ExportTSInSecs: len(elems[0]) <= 10,
 		TS:             parsedTS,
 		From:           model.Time(from),
 		Through:        model.Time(through),

pkg/storage/stores/shipper/indexshipper/tsdb/identifier_test.go

@@ -1,6 +1,7 @@
 package tsdb
 
 import (
+	"encoding/json"
 	"fmt"
 	"math"
 	"testing"
@@ -20,7 +21,7 @@ func TestParseSingleTenantTSDBPath(t *testing.T) {
 			desc:  "simple_works",
 			input: "1-compactor-1-10-ff.tsdb",
 			id: SingleTenantTSDBIdentifier{
-				exportTSInSecs: true,
+				ExportTSInSecs: true,
 				TS:             time.Unix(1, 0),
 				From:           1,
 				Through:        10,
@@ -32,7 +33,7 @@ func TestParseSingleTenantTSDBPath(t *testing.T) {
 			desc:  "simple_works_with_nanosecond",
 			input: "1712534400000000000-compactor-1-10-ff.tsdb",
 			id: SingleTenantTSDBIdentifier{
-				exportTSInSecs: false,
+				ExportTSInSecs: false,
 				TS:             time.Unix(0, 1712534400000000000),
 				From:           1,
 				Through:        10,
@@ -44,7 +45,7 @@ func TestParseSingleTenantTSDBPath(t *testing.T) {
 			desc:  "uint32_max_checksum_works",
 			input: fmt.Sprintf("1-compactor-1-10-%x.tsdb", math.MaxUint32),
 			id: SingleTenantTSDBIdentifier{
-				exportTSInSecs: true,
+				ExportTSInSecs: true,
 				TS:             time.Unix(1, 0),
 				From:           1,
 				Through:        10,
@@ -78,3 +79,29 @@ func TestParseSingleTenantTSDBPath(t *testing.T) {
 		})
 	}
 }
+
+func TestSingleTenantTSDBIdentifierSerialization(t *testing.T) {
+	for _, tc := range []struct {
+		desc  string
+		input SingleTenantTSDBIdentifier
+	}{
+		{
+			desc:  "simple_works",
+			input: SingleTenantTSDBIdentifier{ExportTSInSecs: true, TS: time.Unix(1, 0).UTC(), From: 1, Through: 10, Checksum: 255},
+		},
+		{
+			desc:  "simple_works_with_nanosecond",
+			input: SingleTenantTSDBIdentifier{ExportTSInSecs: false, TS: time.Unix(0, 1712534400000000000).UTC(), From: 1, Through: 10, Checksum: 255},
+		},
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			b, err := json.Marshal(tc.input)
+			require.NoError(t, err)
+
+			var id SingleTenantTSDBIdentifier
+			require.NoError(t, json.Unmarshal(b, &id))
+			require.Equal(t, tc.input.Name(), id.Name())
+			require.Equal(t, tc.input, id)
+		})
+	}
+}