Merge pull request #794 from CosmWasm/792_contract_state_callback

Use callback pattern for contract state iterator

Author: alpe

x/wasm/keeper/genesis.go

@@ -102,25 +102,18 @@ func ExportGenesis(ctx sdk.Context, keeper *Keeper) *types.GenesisState {
 	})
 
 	keeper.IterateContractInfo(ctx, func(addr sdk.AccAddress, contract types.ContractInfo) bool {
-		contractStateIterator := keeper.GetContractState(ctx, addr)
 		var state []types.Model
-		for ; contractStateIterator.Valid(); contractStateIterator.Next() {
-			m := types.Model{
-				Key:   contractStateIterator.Key(),
-				Value: contractStateIterator.Value(),
-			}
-			state = append(state, m)
-		}
+		keeper.IterateContractState(ctx, addr, func(key, value []byte) bool {
+			state = append(state, types.Model{Key: key, Value: value})
+			return false
+		})
 		// redact contract info
 		contract.Created = nil
 		genState.Contracts = append(genState.Contracts, types.Contract{
 			ContractAddress: addr.String(),
 			ContractInfo:    contract,
 			ContractState:   state,
 		})
-
-		contractStateIterator.Close()
-
 		return false
 	})
 

x/wasm/keeper/keeper.go

@@ -688,10 +688,19 @@ func (k Keeper) IterateContractInfo(ctx sdk.Context, cb func(sdk.AccAddress, typ
 	}
 }
 
-func (k Keeper) GetContractState(ctx sdk.Context, contractAddress sdk.AccAddress) sdk.Iterator {
+// IterateContractState iterates through all elements of the key value store for the given contract address and passes
+// them to the provided callback function. The callback method can return true to abort early.
+func (k Keeper) IterateContractState(ctx sdk.Context, contractAddress sdk.AccAddress, cb func(key, value []byte) bool) {
 	prefixStoreKey := types.GetContractStorePrefix(contractAddress)
 	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), prefixStoreKey)
-	return prefixStore.Iterator(nil, nil)
+	iter := prefixStore.Iterator(nil, nil)
+	defer iter.Close()
+
+	for ; iter.Valid(); iter.Next() {
+		if cb(iter.Key(), iter.Value()) {
+			break
+		}
+	}
 }
 
 func (k Keeper) importContractState(ctx sdk.Context, contractAddress sdk.AccAddress, models []types.Model) error {

x/wasm/keeper/legacy_querier.go

@@ -93,15 +93,10 @@ func queryContractState(ctx sdk.Context, bech, queryMethod string, data []byte,
 	case QueryMethodContractStateAll:
 		resultData := make([]types.Model, 0)
 		// this returns a serialized json object (which internally encoded binary fields properly)
-		iter := keeper.GetContractState(ctx, contractAddr)
-		defer iter.Close()
-
-		for ; iter.Valid(); iter.Next() {
-			resultData = append(resultData, types.Model{
-				Key:   iter.Key(),
-				Value: iter.Value(),
-			})
-		}
+		keeper.IterateContractState(ctx, contractAddr, func(key, value []byte) bool {
+			resultData = append(resultData, types.Model{Key: key, Value: value})
+			return false
+		})
 		bz, err := json.Marshal(resultData)
 		if err != nil {
 			return nil, sdkerrors.Wrap(sdkerrors.ErrJSONMarshal, err.Error())

x/wasm/types/exported_keepers.go

@@ -15,7 +15,7 @@ type ViewKeeper interface {
 	GetContractInfo(ctx sdk.Context, contractAddress sdk.AccAddress) *ContractInfo
 	IterateContractInfo(ctx sdk.Context, cb func(sdk.AccAddress, ContractInfo) bool)
 	IterateContractsByCode(ctx sdk.Context, codeID uint64, cb func(address sdk.AccAddress) bool)
-	GetContractState(ctx sdk.Context, contractAddress sdk.AccAddress) sdk.Iterator
+	IterateContractState(ctx sdk.Context, contractAddress sdk.AccAddress, cb func(key, value []byte) bool)
 	GetCodeInfo(ctx sdk.Context, codeID uint64) *CodeInfo
 	IterateCodeInfos(ctx sdk.Context, cb func(uint64, CodeInfo) bool)
 	GetByteCode(ctx sdk.Context, codeID uint64) ([]byte, error)