tsdb: Allow passing a custom compactor to override the default one (#14113)

* expose hook in tsdb to allow customizing compactor

Signed-off-by: Ben Ye <benye@amazon.com>

* address comment

Signed-off-by: Ben Ye <benye@amazon.com>

---------

Signed-off-by: Ben Ye <benye@amazon.com>

tsdb/db.go

@@ -189,8 +189,13 @@ type Options struct {
 
 	// EnableSharding enables query sharding support in TSDB.
 	EnableSharding bool
+
+	// NewCompactorFunc is a function that returns a TSDB compactor.
+	NewCompactorFunc NewCompactorFunc
 }
 
+type NewCompactorFunc func(ctx context.Context, r prometheus.Registerer, l log.Logger, ranges []int64, pool chunkenc.Pool, opts *Options) (Compactor, error)
+
 type BlocksToDeleteFunc func(blocks []*Block) map[ulid.ULID]struct{}
 
 // DB handles reads and writes of time series falling into
@@ -851,13 +856,17 @@ func open(dir string, l log.Logger, r prometheus.Registerer, opts *Options, rngs
 	}
 
 	ctx, cancel := context.WithCancel(context.Background())
-	db.compactor, err = NewLeveledCompactorWithOptions(ctx, r, l, rngs, db.chunkPool, LeveledCompactorOptions{
-		MaxBlockChunkSegmentSize:    opts.MaxBlockChunkSegmentSize,
-		EnableOverlappingCompaction: opts.EnableOverlappingCompaction,
-	})
+	if opts.NewCompactorFunc != nil {
+		db.compactor, err = opts.NewCompactorFunc(ctx, r, l, rngs, db.chunkPool, opts)
+	} else {
+		db.compactor, err = NewLeveledCompactorWithOptions(ctx, r, l, rngs, db.chunkPool, LeveledCompactorOptions{
+			MaxBlockChunkSegmentSize:    opts.MaxBlockChunkSegmentSize,
+			EnableOverlappingCompaction: opts.EnableOverlappingCompaction,
+		})
+	}
 	if err != nil {
 		cancel()
-		return nil, fmt.Errorf("create leveled compactor: %w", err)
+		return nil, fmt.Errorf("create compactor: %w", err)
 	}
 	db.compactCancel = cancel
 

tsdb/db_test.go

@@ -7125,3 +7125,35 @@ func TestAbortBlockCompactions(t *testing.T) {
 	require.True(t, db.head.compactable(), "head should be compactable")
 	require.Equal(t, 4, compactions, "expected 4 compactions to be completed")
 }
+
+func TestNewCompactorFunc(t *testing.T) {
+	opts := DefaultOptions()
+	block1 := ulid.MustNew(1, nil)
+	block2 := ulid.MustNew(2, nil)
+	opts.NewCompactorFunc = func(ctx context.Context, r prometheus.Registerer, l log.Logger, ranges []int64, pool chunkenc.Pool, opts *Options) (Compactor, error) {
+		return &mockCompactorFn{
+			planFn: func() ([]string, error) {
+				return []string{block1.String(), block2.String()}, nil
+			},
+			compactFn: func() (ulid.ULID, error) {
+				return block1, nil
+			},
+			writeFn: func() (ulid.ULID, error) {
+				return block2, nil
+			},
+		}, nil
+	}
+	db := openTestDB(t, opts, nil)
+	defer func() {
+		require.NoError(t, db.Close())
+	}()
+	plans, err := db.compactor.Plan("")
+	require.NoError(t, err)
+	require.Equal(t, []string{block1.String(), block2.String()}, plans)
+	ulid, err := db.compactor.Compact("", nil, nil)
+	require.NoError(t, err)
+	require.Equal(t, block1, ulid)
+	ulid, err = db.compactor.Write("", nil, 0, 1, nil)
+	require.NoError(t, err)
+	require.Equal(t, block2, ulid)
+}