Add a function to cleanup tombstones.

Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>

block.go

@@ -335,6 +335,20 @@ Outer:
 	return writeMetaFile(pb.dir, &pb.meta)
 }
 
+// CleanTombstones will rewrite the block if there any tombstones to remove them
+// and returns if there was a re-write.
+func (pb *Block) CleanTombstones(dest string, c Compactor) (bool, error) {
+	if len(pb.tombstones) == 0 {
+		return false, nil
+	}
+
+	if err := c.Write(dest, pb, pb.meta.MinTime, pb.meta.MaxTime); err != nil {
+		return false, err
+	}
+
+	return true, nil
+}
+
 // Snapshot creates snapshot of the block into dir.
 func (pb *Block) Snapshot(dir string) error {
 	blockDir := filepath.Join(dir, pb.meta.ULID.String())

db.go

@@ -122,6 +122,7 @@ type dbMetrics struct {
 	reloads              prometheus.Counter
 	reloadsFailed        prometheus.Counter
 	compactionsTriggered prometheus.Counter
+	tombCleanTimer       prometheus.Histogram
 }
 
 func newDBMetrics(db *DB, r prometheus.Registerer) *dbMetrics {
@@ -147,6 +148,10 @@ func newDBMetrics(db *DB, r prometheus.Registerer) *dbMetrics {
 		Name: "prometheus_tsdb_compactions_triggered_total",
 		Help: "Total number of triggered compactions for the partition.",
 	})
+	m.tombCleanTimer = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Name: "prometheus_tsdb_tombstone_cleanup_seconds",
+		Help: "The time taken to recompact blocks to remove tombstones.",
+	})
 
 	if r != nil {
 		r.MustRegister(
@@ -154,6 +159,7 @@ func newDBMetrics(db *DB, r prometheus.Registerer) *dbMetrics {
 			m.reloads,
 			m.reloadsFailed,
 			m.compactionsTriggered,
+			m.tombCleanTimer,
 		)
 	}
 	return m
@@ -686,6 +692,37 @@ func (db *DB) Delete(mint, maxt int64, ms ...labels.Matcher) error {
 	return nil
 }
 
+// CleanTombstones re-writes any blocks with tombstones.
+func (db *DB) CleanTombstones() error {
+	db.cmtx.Lock()
+	defer db.cmtx.Unlock()
+
+	start := time.Now()
+	defer db.metrics.tombCleanTimer.Observe(float64(time.Since(start).Seconds()))
+
+	db.mtx.RLock()
+	blocks := db.blocks[:]
+	db.mtx.RUnlock()
+
+	deleted := []string{}
+	for _, b := range blocks {
+		ok, err := b.CleanTombstones(db.Dir(), db.compactor)
+		if err != nil {
+			return errors.Wrapf(err, "clean tombstones: %s", b.Dir())
+		}
+
+		if ok {
+			deleted = append(deleted, b.Dir())
+		}
+	}
+
+	if len(deleted) == 0 {
+		return nil
+	}
+
+	return errors.Wrap(db.reload(deleted...), "reload blocks")
+}
+
 func intervalOverlap(amin, amax, bmin, bmax int64) bool {
 	// Checks Overlap: http://stackoverflow.com/questions/3269434/
 	return amin <= bmax && bmin <= amax

db_test.go

@@ -551,3 +551,93 @@ func TestWALFlushedOnDBClose(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, values, []string{"labelvalue"})
 }
+
+func TestTombstoneClean(t *testing.T) {
+	numSamples := int64(10)
+
+	db, close := openTestDB(t, nil)
+	defer close()
+
+	app := db.Appender()
+
+	smpls := make([]float64, numSamples)
+	for i := int64(0); i < numSamples; i++ {
+		smpls[i] = rand.Float64()
+		app.Add(labels.Labels{{"a", "b"}}, i, smpls[i])
+	}
+
+	require.NoError(t, app.Commit())
+	cases := []struct {
+		intervals Intervals
+		remaint   []int64
+	}{
+		{
+			intervals: Intervals{{1, 3}, {4, 7}},
+			remaint:   []int64{0, 8, 9},
+		},
+	}
+
+	for _, c := range cases {
+		// Delete the ranges.
+
+		// create snapshot
+		snap, err := ioutil.TempDir("", "snap")
+		require.NoError(t, err)
+		require.NoError(t, db.Snapshot(snap))
+		require.NoError(t, db.Close())
+
+		// reopen DB from snapshot
+		db, err = Open(snap, nil, nil, nil)
+		require.NoError(t, err)
+
+		for _, r := range c.intervals {
+			require.NoError(t, db.Delete(r.Mint, r.Maxt, labels.NewEqualMatcher("a", "b")))
+		}
+
+		// All of the setup for THIS line.
+		require.NoError(t, db.CleanTombstones())
+
+		// Compare the result.
+		q, err := db.Querier(0, numSamples)
+		require.NoError(t, err)
+
+		res := q.Select(labels.NewEqualMatcher("a", "b"))
+
+		expSamples := make([]sample, 0, len(c.remaint))
+		for _, ts := range c.remaint {
+			expSamples = append(expSamples, sample{ts, smpls[ts]})
+		}
+
+		expss := newListSeriesSet([]Series{
+			newSeries(map[string]string{"a": "b"}, expSamples),
+		})
+
+		if len(expSamples) == 0 {
+			require.False(t, res.Next())
+			continue
+		}
+
+		for {
+			eok, rok := expss.Next(), res.Next()
+			require.Equal(t, eok, rok, "next")
+
+			if !eok {
+				break
+			}
+			sexp := expss.At()
+			sres := res.At()
+
+			require.Equal(t, sexp.Labels(), sres.Labels(), "labels")
+
+			smplExp, errExp := expandSeriesIterator(sexp.Iterator())
+			smplRes, errRes := expandSeriesIterator(sres.Iterator())
+
+			require.Equal(t, errExp, errRes, "samples error")
+			require.Equal(t, smplExp, smplRes, "samples")
+		}
+
+		for _, b := range db.blocks {
+			Equals(t, 0, len(b.tombstones))
+		}
+	}
+}