rpc method to get statediff at specific block; requires archival node or the block be within the pruning range

statediff/api.go

@@ -89,3 +89,8 @@ func (api *PublicStateDiffAPI) Stream(ctx context.Context) (*rpc.Subscription, e
 
 	return rpcSub, nil
 }
+
+// StateDiffAt returns a statediff payload at the specific blockheight
+func (api *PublicStateDiffAPI) StateDiffAt(ctx context.Context, blockNumber uint64) (*Payload, error) {
+	return api.sds.StateDiffAt(blockNumber)
+}

statediff/service.go

@@ -39,6 +39,7 @@ const chainEventChanSize = 20000
 type blockChain interface {
 	SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription
 	GetBlockByHash(hash common.Hash) *types.Block
+	GetBlockByNumber(number uint64) *types.Block
 	AddToStateDiffProcessedCollection(hash common.Hash)
 	GetReceiptsByHash(hash common.Hash) types.Receipts
 }
@@ -53,6 +54,8 @@ type IService interface {
 	Subscribe(id rpc.ID, sub chan<- Payload, quitChan chan<- bool)
 	// Method to unsubscribe from state diff processing
 	Unsubscribe(id rpc.ID) error
+	// Method to get statediff at specific block
+	StateDiffAt(blockNumber uint64) (*Payload, error)
 }
 
 // Service is the underlying struct for the state diffing service
@@ -132,9 +135,11 @@ func (sds *Service) Loop(chainEventCh chan core.ChainEvent) {
 				log.Error(fmt.Sprintf("Parent block is nil, skipping this block (%d)", currentBlock.Number()))
 				continue
 			}
-			if err := sds.processStateDiff(currentBlock, parentBlock); err != nil {
+			payload, err := sds.processStateDiff(currentBlock, parentBlock)
+			if err != nil {
 				log.Error(fmt.Sprintf("Error building statediff for block %d; error: ", currentBlock.Number()) + err.Error())
 			}
+			sds.send(*payload)
 		case err := <-errCh:
 			log.Warn("Error from chain event subscription, breaking loop", "error", err)
 			sds.close()
@@ -148,14 +153,14 @@ func (sds *Service) Loop(chainEventCh chan core.ChainEvent) {
 }
 
 // processStateDiff method builds the state diff payload from the current and parent block before sending it to listening subscriptions
-func (sds *Service) processStateDiff(currentBlock, parentBlock *types.Block) error {
+func (sds *Service) processStateDiff(currentBlock, parentBlock *types.Block) (*Payload, error) {
 	stateDiff, err := sds.Builder.BuildStateDiff(parentBlock.Root(), currentBlock.Root(), currentBlock.Number(), currentBlock.Hash())
 	if err != nil {
-		return err
+		return nil, err
 	}
 	stateDiffRlp, err := rlp.EncodeToBytes(stateDiff)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	payload := Payload{
 		StateDiffRlp: stateDiffRlp,
@@ -163,19 +168,17 @@ func (sds *Service) processStateDiff(currentBlock, parentBlock *types.Block) err
 	if sds.StreamBlock {
 		blockBuff := new(bytes.Buffer)
 		if err = currentBlock.EncodeRLP(blockBuff); err != nil {
-			return err
+			return nil, err
 		}
 		payload.BlockRlp = blockBuff.Bytes()
 		receiptBuff := new(bytes.Buffer)
 		receipts := sds.BlockChain.GetReceiptsByHash(currentBlock.Hash())
 		if err = rlp.Encode(receiptBuff, receipts); err != nil {
-			return err
+			return nil, err
 		}
 		payload.ReceiptsRlp = receiptBuff.Bytes()
 	}
-
-	sds.send(payload)
-	return nil
+	return &payload, nil
 }
 
 // Subscribe is used by the API to subscribe to the service loop
@@ -269,3 +272,12 @@ func (sds *Service) close() {
 	}
 	sds.Unlock()
 }
+
+// StateDiffAt returns a statediff payload at the specific blockheight
+// This operation cannot be performed back past the point of db pruning; it requires an archival node
+func (sds *Service) StateDiffAt(blockNumber uint64) (*Payload, error) {
+	currentBlock := sds.BlockChain.GetBlockByNumber(blockNumber)
+	parentBlock := sds.BlockChain.GetBlockByHash(currentBlock.ParentHash())
+	log.Info(fmt.Sprintf("sending state diff at %d", blockNumber))
+	return sds.processStateDiff(currentBlock, parentBlock)
+}

statediff/service_test.go

@@ -194,3 +194,75 @@ func testErrorInBlockLoop(t *testing.T) {
 		t.Logf("Actual does not equal expected.\nactual:%+v\nexpected: %+v", builder.NewStateRoot, testBlock1.Root())
 	}
 }
+
+func TestGetStateDiffAt(t *testing.T) {
+	testErrorInStateDiffAt(t)
+}
+
+func testErrorInStateDiffAt(t *testing.T) {
+	mockStateDiff := statediff.StateDiff{
+		BlockNumber: testBlock1.Number(),
+		BlockHash:   testBlock1.Hash(),
+	}
+	expectedStateDiffRlp, err := rlp.EncodeToBytes(mockStateDiff)
+	if err != nil {
+		t.Error(err)
+	}
+	expectedReceiptsRlp, err := rlp.EncodeToBytes(testReceipts1)
+	if err != nil {
+		t.Error(err)
+	}
+	expectedBlockRlp, err := rlp.EncodeToBytes(testBlock1)
+	if err != nil {
+		t.Error(err)
+	}
+	expectedStateDiffPayload := statediff.Payload{
+		StateDiffRlp: expectedStateDiffRlp,
+		ReceiptsRlp:  expectedReceiptsRlp,
+		BlockRlp:     expectedBlockRlp,
+	}
+	expectedStateDiffPayloadRlp, err := rlp.EncodeToBytes(expectedStateDiffPayload)
+	if err != nil {
+		t.Error(err)
+	}
+	builder := mocks.Builder{}
+	builder.SetStateDiffToBuild(mockStateDiff)
+	blockChain := mocks.BlockChain{}
+	blockMapping := make(map[common.Hash]*types.Block)
+	blockMapping[parentBlock1.Hash()] = parentBlock1
+	blockChain.SetParentBlocksToReturn(blockMapping)
+	blockChain.SetBlockForNumber(testBlock1, testBlock1.NumberU64())
+	blockChain.SetReceiptsForHash(testBlock1.Hash(), testReceipts1)
+	service := statediff.Service{
+		Mutex:         sync.Mutex{},
+		Builder:       &builder,
+		BlockChain:    &blockChain,
+		QuitChan:      make(chan bool),
+		Subscriptions: make(map[rpc.ID]statediff.Subscription),
+		StreamBlock:   true,
+	}
+	stateDiffPayload, err := service.StateDiffAt(testBlock1.NumberU64())
+	if err != nil {
+		t.Error(err)
+	}
+	stateDiffPayloadRlp, err := rlp.EncodeToBytes(stateDiffPayload)
+	if err != nil {
+		t.Error(err)
+	}
+	if !bytes.Equal(builder.BlockHash.Bytes(), testBlock1.Hash().Bytes()) {
+		t.Error("Test failure:", t.Name())
+		t.Logf("Actual does not equal expected.\nactual:%+v\nexpected: %+v", builder.BlockHash, testBlock1.Hash())
+	}
+	if !bytes.Equal(builder.OldStateRoot.Bytes(), parentBlock1.Root().Bytes()) {
+		t.Error("Test failure:", t.Name())
+		t.Logf("Actual does not equal expected.\nactual:%+v\nexpected: %+v", builder.OldStateRoot, parentBlock1.Root())
+	}
+	if !bytes.Equal(builder.NewStateRoot.Bytes(), testBlock1.Root().Bytes()) {
+		t.Error("Test failure:", t.Name())
+		t.Logf("Actual does not equal expected.\nactual:%+v\nexpected: %+v", builder.NewStateRoot, testBlock1.Root())
+	}
+	if !bytes.Equal(expectedStateDiffPayloadRlp, stateDiffPayloadRlp) {
+		t.Error("Test failure:", t.Name())
+		t.Logf("Actual does not equal expected.\nactual:%+v\nexpected: %+v", expectedStateDiffPayload, stateDiffPayload)
+	}
+}

statediff/testhelpers/mocks/api.go

@@ -185,3 +185,8 @@ func (sds *MockStateDiffService) Stop() error {
 	close(sds.QuitChan)
 	return nil
 }
+
+// StateDiffAt mock method
+func (sds *MockStateDiffService) StateDiffAt(blockNumber uint64) (*statediff.Payload, error) {
+	panic("implement me")
+}

statediff/testhelpers/mocks/blockchain.go

@@ -31,6 +31,7 @@ import (
 type BlockChain struct {
 	ParentHashesLookedUp         []common.Hash
 	parentBlocksToReturn         map[common.Hash]*types.Block
+	parentBlocksToReturnByNumber map[uint64]*types.Block
 	callCount                    int
 	ChainEvents                  []core.ChainEvent
 	Receipts                     map[common.Hash]types.Receipts
@@ -100,3 +101,16 @@ func (blockChain *BlockChain) SetReceiptsForHash(hash common.Hash, receipts type
 func (blockChain *BlockChain) GetReceiptsByHash(hash common.Hash) types.Receipts {
 	return blockChain.Receipts[hash]
 }
+
+// SetBlockForNumber mock method
+func (blockChain *BlockChain) SetBlockForNumber(block *types.Block, number uint64) {
+	if blockChain.parentBlocksToReturnByNumber == nil {
+		blockChain.parentBlocksToReturnByNumber = make(map[uint64]*types.Block)
+	}
+	blockChain.parentBlocksToReturnByNumber[number] = block
+}
+
+// GetBlockByNumber mock method
+func (blockChain *BlockChain) GetBlockByNumber(number uint64) *types.Block {
+	return blockChain.parentBlocksToReturnByNumber[number]
+}