Fix 'chunks.HeadReadWriter: maxt of the files are not set' error (#7856)

* Fix chunks.HeadReadWriter: maxt of the files are not set
Signed-off-by: NGanesh Vernekar <cs15btech11018@iith.ac.in>

tsdb/chunks/head_chunks.go

@@ -539,9 +539,7 @@ func (cdm *ChunkDiskMapper) IterateAllChunks(f func(seriesRef, chunkRef uint64,
 	defer cdm.writePathMtx.Unlock()
 
 	defer func() {
-		if err == nil {
-			cdm.fileMaxtSet = true
-		}
+		cdm.fileMaxtSet = true
 	}()
 
 	chkCRC32 := newCRC32()

tsdb/chunks/head_chunks_test.go

@@ -15,6 +15,7 @@ package chunks
 
 import (
 	"encoding/binary"
+	"errors"
 	"io/ioutil"
 	"math/rand"
 	"os"
@@ -25,10 +26,9 @@ import (
 )
 
 func TestHeadReadWriter_WriteChunk_Chunk_IterateChunks(t *testing.T) {
-	hrw, close := testHeadReadWriter(t)
+	hrw := testHeadReadWriter(t)
 	defer func() {
 		testutil.Ok(t, hrw.Close())
-		close()
 	}()
 
 	expectedBytes := []byte{}
@@ -162,10 +162,9 @@ func TestHeadReadWriter_WriteChunk_Chunk_IterateChunks(t *testing.T) {
 // * Empty current file does not lead to creation of another file after truncation.
 // * Non-empty current file leads to creation of another file after truncation.
 func TestHeadReadWriter_Truncate(t *testing.T) {
-	hrw, close := testHeadReadWriter(t)
+	hrw := testHeadReadWriter(t)
 	defer func() {
 		testutil.Ok(t, hrw.Close())
-		close()
 	}()
 
 	timeRange := 0
@@ -268,10 +267,9 @@ func TestHeadReadWriter_Truncate(t *testing.T) {
 // the truncation used to check all the files for deletion and end up
 // deleting empty files in between and breaking the sequence.
 func TestHeadReadWriter_Truncate_NoUnsequentialFiles(t *testing.T) {
-	hrw, close := testHeadReadWriter(t)
+	hrw := testHeadReadWriter(t)
 	defer func() {
 		testutil.Ok(t, hrw.Close())
-		close()
 	}()
 
 	timeRange := 0
@@ -337,17 +335,47 @@ func TestHeadReadWriter_Truncate_NoUnsequentialFiles(t *testing.T) {
 	verifyFiles([]int{3, 4, 5, 6, 7})
 }
 
-func testHeadReadWriter(t *testing.T) (hrw *ChunkDiskMapper, close func()) {
+// TestHeadReadWriter_TruncateAfterIterateChunksError tests for
+// https://github.com/prometheus/prometheus/issues/7753
+func TestHeadReadWriter_TruncateAfterFailedIterateChunks(t *testing.T) {
+	hrw := testHeadReadWriter(t)
+	defer func() {
+		testutil.Ok(t, hrw.Close())
+	}()
+
+	// Write a chunks to iterate on it later.
+	_, err := hrw.WriteChunk(1, 0, 1000, randomChunk(t))
+	testutil.Ok(t, err)
+
+	dir := hrw.dir.Name()
+	testutil.Ok(t, hrw.Close())
+
+	// Restarting to recreate https://github.com/prometheus/prometheus/issues/7753.
+	hrw, err = NewChunkDiskMapper(dir, chunkenc.NewPool())
+	testutil.Ok(t, err)
+
+	// Forcefully failing IterateAllChunks.
+	testutil.NotOk(t, hrw.IterateAllChunks(func(_, _ uint64, _, _ int64, _ uint16) error {
+		return errors.New("random error")
+	}))
+
+	// Truncation call should not return error after IterateAllChunks fails.
+	testutil.Ok(t, hrw.Truncate(2000))
+}
+
+func testHeadReadWriter(t *testing.T) *ChunkDiskMapper {
 	tmpdir, err := ioutil.TempDir("", "data")
 	testutil.Ok(t, err)
-	hrw, err = NewChunkDiskMapper(tmpdir, chunkenc.NewPool())
+	t.Cleanup(func() {
+		testutil.Ok(t, os.RemoveAll(tmpdir))
+	})
+
+	hrw, err := NewChunkDiskMapper(tmpdir, chunkenc.NewPool())
 	testutil.Ok(t, err)
 	testutil.Assert(t, !hrw.fileMaxtSet, "")
 	testutil.Ok(t, hrw.IterateAllChunks(func(_, _ uint64, _, _ int64, _ uint16) error { return nil }))
 	testutil.Assert(t, hrw.fileMaxtSet, "")
-	return hrw, func() {
-		testutil.Ok(t, os.RemoveAll(tmpdir))
-	}
+	return hrw
 }
 
 func randomChunk(t *testing.T) chunkenc.Chunk {

tsdb/head.go

@@ -652,7 +652,7 @@ func (h *Head) Init(minValidTime int64) error {
 		}
 		// If this fails, data will be recovered from WAL.
 		// Hence we wont lose any data (given WAL is not corrupt).
-		h.removeCorruptedMmappedChunks(err)
+		mmappedChunks = h.removeCorruptedMmappedChunks(err)
 	}
 
 	level.Info(h.logger).Log("msg", "On-disk memory mappable chunks replay completed", "duration", time.Since(start).String())