Function TestL0GCBug

db2_test.go:610–690

The test ensures we don't lose data when badger is opened with KeepL0InMemory and GC is being done.

(t *testing.T)

// The test ensures we don't lose data when badger is opened with KeepL0InMemory and GC is being
// done.
func TestL0GCBug(t *testing.T) {
	dir, err := ioutil.TempDir("", "badger-test")
	require.NoError(t, err)
	defer removeDir(dir)

	// Do not change any of the options below unless it's necessary.
	opts := getTestOptions(dir)
	opts.NumLevelZeroTables = 50
	opts.NumLevelZeroTablesStall = 51
	opts.ValueLogMaxEntries = 2
	opts.ValueThreshold = 2
	opts.KeepL0InMemory = true
	// Setting LoadingMode to mmap seems to cause segmentation fault while closing DB.
	opts.ValueLogLoadingMode = options.FileIO
	opts.TableLoadingMode = options.FileIO

	db1, err := Open(opts)
	require.NoError(t, err)
	key := func(i int) []byte {
		return []byte(fmt.Sprintf("%10d", i))
	}
	val := []byte{1, 1, 1, 1, 1, 1, 1, 1}
	// Insert 100 entries. This will create about 50*3 vlog files and 6 SST files.
	for i := 0; i < 3; i++ {
		for j := 0; j < 100; j++ {
			err = db1.Update(func(txn *Txn) error {
				return txn.SetEntry(NewEntry(key(j), val))
			})
			require.NoError(t, err)
		}
	}
	// Run value log GC multiple times. This would ensure at least
	// one value log file is garbage collected.
	success := 0
	for i := 0; i < 10; i++ {
		err := db1.RunValueLogGC(0.01)
		if err == nil {
			success++
		}
		if err != nil && err != ErrNoRewrite {
			t.Fatalf(err.Error())
		}
	}
	// Ensure alteast one GC call was successful.
	require.NotZero(t, success)
	// CheckKeys reads all the keys previously stored.
	checkKeys := func(db *DB) {
		for i := 0; i < 100; i++ {
			err := db.View(func(txn *Txn) error {
				item, err := txn.Get(key(i))
				require.NoError(t, err)
				val1 := getItemValue(t, item)
				require.Equal(t, val, val1)
				return nil
			})
			require.NoError(t, err)
		}
	}