CNS-381: timerstore: add version to support migrations

common/timer.go

@@ -77,12 +77,33 @@ type TimerStore struct {
 	callbacks [2]TimerCallback // as per TimerType
 }
 
+func TimerVersion() uint64 {
+	return 1
+}
+
 // NewTimerStore returns a new TimerStore object
 func NewTimerStore(storeKey sdk.StoreKey, cdc codec.BinaryCodec, prefix string) *TimerStore {
 	tstore := TimerStore{storeKey: storeKey, cdc: cdc, prefix: prefix}
 	return &tstore
 }
 
+func (tstore *TimerStore) getVersion(ctx sdk.Context) uint64 {
+	store := prefix.NewStore(ctx.KVStore(tstore.storeKey), types.KeyPrefix(tstore.prefix))
+
+	b := store.Get(types.KeyPrefix(types.TimerVersionKey))
+	if b == nil {
+		return 1
+	}
+
+	return types.DecodeKey(b)
+}
+
+func (tstore *TimerStore) setVersion(ctx sdk.Context, val uint64) {
+	store := prefix.NewStore(ctx.KVStore(tstore.storeKey), types.KeyPrefix(tstore.prefix))
+	b := types.EncodeKey(val)
+	store.Set(types.KeyPrefix(types.TimerVersionKey), b)
+}
+
 func (tstore *TimerStore) WithCallbackByBlockHeight(callback func(ctx sdk.Context, data string)) *TimerStore {
 	tstoreNew := tstore
 	tstoreNew.callbacks[types.BlockHeight] = callback

common/timer_migrate.go

@@ -0,0 +1,37 @@
+package common
+
+import (
+	"fmt"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+)
+
+func (tstore *TimerStore) prefixForErrors(from uint64) string {
+	return fmt.Sprintf("TimerStore: migration from version %d", from)
+}
+
+var timerMigrators = map[int]func (sdk.Context, *TimerStore) error{
+	// fill with map entrys like "1: timerMigrate1to2"
+}
+
+func (tstore *TimerStore) MigrateVersion(ctx sdk.Context) (err error) {
+	from := tstore.getVersion(ctx)
+	to := TimerVersion()
+
+	for from < to {
+		function, ok := timerMigrators[int(from)]
+		if !ok {
+			return fmt.Errorf("%s not available", prefixForErrors(from))
+		}
+
+		err = function(ctx, tstore)
+		if err != nil {
+			return err
+		}
+
+		from += 1
+	}
+
+	tstore.setVersion(ctx, to)
+	return nil
+}

common/types/keys.go

@@ -24,6 +24,7 @@ const (
 )
 
 const (
+	TimerVersionKey = "Entry_Version"
 	NextTimerPrefix = "Timer_Next_"
 	TimerPrefix     = "Timer_Value_"
 )