integrate backfill into storage watcher; documentation for storage backfill

cmd/execute.go

@@ -17,21 +17,25 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"plugin"
 	syn "sync"
 	"time"
 
+	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/ethereum/go-ethereum/statediff"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 
 	"github.com/vulcanize/vulcanizedb/libraries/shared/constants"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/fetcher"
-	storageUtils "github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
+	"github.com/vulcanize/vulcanizedb/libraries/shared/storage"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/streamer"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/transformer"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/watcher"
+	"github.com/vulcanize/vulcanizedb/pkg/eth/client"
 	"github.com/vulcanize/vulcanizedb/pkg/fs"
 	"github.com/vulcanize/vulcanizedb/utils"
 )
@@ -186,13 +190,29 @@ func watchEthStorage(w watcher.IStorageWatcher, wg *syn.WaitGroup) {
 	defer wg.Done()
 	// Execute over the StorageTransformerInitializer set using the storage watcher
 	LogWithCommand.Info("executing storage transformers")
-	ticker := time.NewTicker(pollingInterval)
+	on := viper.GetBool("storageBackFill.on")
-	defer ticker.Stop()
+	if on {
-	for range ticker.C {
+		go backFillStorage(w)
-		errs := make(chan error)
-		diffs := make(chan storageUtils.StorageDiff)
-		w.Execute(diffs, errs, queueRecheckInterval)
 	}
+	w.Execute(queueRecheckInterval, on)
+}
+
+func backFillStorage(w watcher.IStorageWatcher) {
+	// configure archival rpc client
+	archivalRPCPath := viper.GetString("storageBackFill.rpcPath")
+	if archivalRPCPath == "" {
+		LogWithCommand.Fatal(errors.New("storage backfill is turned on but no rpc path is provided"))
+	}
+	rawRPCClient, dialErr := rpc.Dial(archivalRPCPath)
+	if dialErr != nil {
+		LogWithCommand.Fatal(dialErr)
+	}
+	rpcClient := client.NewRpcClient(rawRPCClient, archivalRPCPath)
+	// find min deployment block
+	minDeploymentBlock := viper.GetInt("storageBackFill.startingBlock")
+	stateDiffFetcher := fetcher.NewStateDiffFetcher(rpcClient)
+	backFiller := storage.NewStorageBackFiller(stateDiffFetcher)
+	w.BackFill(backFiller, minDeploymentBlock)
 }
 
 func watchEthContract(w *watcher.ContractWatcher, wg *syn.WaitGroup) {

documentation/custom-transformers.md

@@ -194,3 +194,19 @@ func (e exporter) Export() []interface1.EventTransformerInitializer, []interface
         }
 }
 ```
+
+### Storage backfilling
+Storage transformers stream data from a geth subscription or parity csv file where the storage diffs are produced and emitted as the
+full sync progresses. If the transformers have missed consuming a range of diffs due to lag in the startup of the processes or due to misalignment of the sync,
+we can configure our storage transformers to backfill missing diffs from a [modified archival geth client](https://github.com/vulcanize/go-ethereum/tree/statediff_at).
+
+To do so, add the following fields to the config file.
+```toml
+[storageBackFill]
+    on = false
+    rpcPath = ""
+    startingBlock = 0
+```
+- `on` is set to `true` to turn the backfill process on
+- `rpcPath` is the websocket or ipc path to the modified archival geth node that exposes the `StateDiffAt` rpc endpoint we can use to backfill storage diffs
+- `startingBlock` is the block height at which we want to begin the backfill process; the height of the earliest contract deployment

libraries/shared/fetcher/geth_rpc_storage_fetcher.go

@@ -1,17 +1,18 @@
-// Copyright 2019 Vulcanize
+// VulcanizeDB
-//
+// Copyright © 2019 Vulcanize
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
 
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
 package fetcher
 
 import (
@@ -62,14 +63,15 @@ func (fetcher GethRPCStorageFetcher) FetchStorageDiffs(out chan<- utils.StorageD
 			logrus.Trace(fmt.Sprintf("iterating through %d Storage values on account", len(account.Storage)))
 			for _, storage := range account.Storage {
 				diff, formatErr := utils.FromGethStateDiff(account, stateDiff, storage)
+				if formatErr != nil {
+					errs <- formatErr
+					continue
+				}
 				logrus.Trace("adding storage diff to out channel",
 					"keccak of address: ", diff.HashedAddress.Hex(),
 					"block height: ", diff.BlockHeight,
 					"storage key: ", diff.StorageKey.Hex(),
 					"storage value: ", diff.StorageValue.Hex())
-				if formatErr != nil {
-					errs <- formatErr
-				}
 
 				out <- diff
 			}

libraries/shared/fetcher/geth_rpc_storage_fetcher_test.go

@@ -1,16 +1,18 @@
-// Copyright 2019 Vulcanize
+// VulcanizeDB
-//
+// Copyright © 2019 Vulcanize
-// Licensed under the Apache License, Version 2.0 (the "License");
+
-// you may not use this file except in compliance with the License.
+// This program is free software: you can redistribute it and/or modify
-// You may obtain a copy of the License at
+// it under the terms of the GNU Affero General Public License as published by
-//
+// the Free Software Foundation, either version 3 of the License, or
-//      http://www.apache.org/licenses/LICENSE-2.0
+// (at your option) any later version.
-//
+
-// Unless required by applicable law or agreed to in writing, software
+// This program is distributed in the hope that it will be useful,
-// distributed under the License is distributed on an "AS IS" BASIS,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// See the License for the specific language governing permissions and
+// GNU Affero General Public License for more details.
-// limitations under the License.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 package fetcher_test
 
@@ -21,6 +23,7 @@ import (
 	"github.com/ethereum/go-ethereum/statediff"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
+
 	"github.com/vulcanize/vulcanizedb/libraries/shared/fetcher"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/test_data"

libraries/shared/fetcher/state_diff_fetcher.go

@@ -17,13 +17,14 @@
 package fetcher
 
 import (
+	"fmt"
 	"github.com/ethereum/go-ethereum/statediff"
 
-	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
+	"github.com/vulcanize/vulcanizedb/pkg/eth/client"
 )
 
-// IStateDiffFetcher is the state diff fetching interface
+// StateDiffFetcher is the state diff fetching interface
-type IStateDiffFetcher interface {
+type StateDiffFetcher interface {
 	FetchStateDiffsAt(blockHeights []uint64) ([]*statediff.Payload, error)
 }
 
@@ -32,23 +33,23 @@ type BatchClient interface {
 	BatchCall(batch []client.BatchElem) error
 }
 
-// StateDiffFetcher is the state diff fetching struct
+// stateDiffFetcher is the state diff fetching struct
-type StateDiffFetcher struct {
+type stateDiffFetcher struct {
 	client BatchClient
 }
 
 const method = "statediff_stateDiffAt"
 
 // NewStateDiffFetcher returns a IStateDiffFetcher
-func NewStateDiffFetcher(bc BatchClient) IStateDiffFetcher {
+func NewStateDiffFetcher(bc BatchClient) StateDiffFetcher {
-	return &StateDiffFetcher{
+	return &stateDiffFetcher{
 		client: bc,
 	}
 }
 
 // FetchStateDiffsAt fetches the statediff payloads at the given block heights
 // Calls StateDiffAt(ctx context.Context, blockNumber uint64) (*Payload, error)
-func (sdf *StateDiffFetcher) FetchStateDiffsAt(blockHeights []uint64) ([]*statediff.Payload, error) {
+func (fetcher *stateDiffFetcher) FetchStateDiffsAt(blockHeights []uint64) ([]*statediff.Payload, error) {
 	batch := make([]client.BatchElem, 0)
 	for _, height := range blockHeights {
 		batch = append(batch, client.BatchElem{
@@ -57,14 +58,14 @@ func (sdf *StateDiffFetcher) FetchStateDiffsAt(blockHeights []uint64) ([]*stated
 			Result: new(statediff.Payload),
 		})
 	}
-	batchErr := sdf.client.BatchCall(batch)
+	batchErr := fetcher.client.BatchCall(batch)
 	if batchErr != nil {
-		return nil, batchErr
+		return nil, fmt.Errorf("stateDiffFetcher err: %s", batchErr.Error())
 	}
 	results := make([]*statediff.Payload, 0, len(blockHeights))
 	for _, batchElem := range batch {
 		if batchElem.Error != nil {
-			return nil, batchElem.Error
+			return nil, fmt.Errorf("stateDiffFetcher err: %s", batchElem.Error.Error())
 		}
 		results = append(results, batchElem.Result.(*statediff.Payload))
 	}

libraries/shared/fetcher/state_diff_fetcher_test.go

@@ -18,66 +18,25 @@ package fetcher_test
 
 import (
 	"bytes"
-	"encoding/json"
-	"errors"
-
-	"github.com/vulcanize/vulcanizedb/libraries/shared/fetcher"
 
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/statediff"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 
+	"github.com/vulcanize/vulcanizedb/libraries/shared/fetcher"
+	"github.com/vulcanize/vulcanizedb/libraries/shared/mocks"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/test_data"
-	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
 )
 
-type mockClient struct {
-	MappedStateDiffAt map[uint64][]byte
-}
-
-// SetReturnDiffAt method to set what statediffs the mock client returns
-func (mc *mockClient) SetReturnDiffAt(height uint64, diffPayload statediff.Payload) error {
-	if mc.MappedStateDiffAt == nil {
-		mc.MappedStateDiffAt = make(map[uint64][]byte)
-	}
-	by, err := json.Marshal(diffPayload)
-	if err != nil {
-		return err
-	}
-	mc.MappedStateDiffAt[height] = by
-	return nil
-}
-
-// BatchCall mockClient method to simulate batch call to geth
-func (mc *mockClient) BatchCall(batch []client.BatchElem) error {
-	if mc.MappedStateDiffAt == nil {
-		return errors.New("mockclient needs to be initialized with statediff payloads and errors")
-	}
-	for _, batchElem := range batch {
-		if len(batchElem.Args) != 1 {
-			return errors.New("expected batch elem to contain single argument")
-		}
-		blockHeight, ok := batchElem.Args[0].(uint64)
-		if !ok {
-			return errors.New("expected batch elem argument to be a uint64")
-		}
-		err := json.Unmarshal(mc.MappedStateDiffAt[blockHeight], batchElem.Result)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
 var _ = Describe("StateDiffFetcher", func() {
 	Describe("FetchStateDiffsAt", func() {
 		var (
-			mc               *mockClient
+			mc               *mocks.BackFillerClient
-			stateDiffFetcher fetcher.IStateDiffFetcher
+			stateDiffFetcher fetcher.StateDiffFetcher
 		)
 		BeforeEach(func() {
-			mc = new(mockClient)
+			mc = new(mocks.BackFillerClient)
 			setDiffAtErr1 := mc.SetReturnDiffAt(test_data.BlockNumber.Uint64(), test_data.MockStatediffPayload)
 			Expect(setDiffAtErr1).ToNot(HaveOccurred())
 			setDiffAtErr2 := mc.SetReturnDiffAt(test_data.BlockNumber2.Uint64(), test_data.MockStatediffPayload2)

libraries/shared/mocks/backfiller.go

@@ -0,0 +1,39 @@
+// VulcanizeDB
+// Copyright © 2019 Vulcanize
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package mocks
+
+import "github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
+
+// BackFiller mock for tests
+type BackFiller struct {
+	StorageDiffsToReturn []utils.StorageDiff
+	BackFillErr          error
+	PassedStartingBlock  uint64
+	PassedEndingBlock    uint64
+}
+
+// SetStorageDiffsToReturn for tests
+func (backFiller *BackFiller) SetStorageDiffsToReturn(diffs []utils.StorageDiff) {
+	backFiller.StorageDiffsToReturn = diffs
+}
+
+// BackFill mock method
+func (backFiller *BackFiller) BackFill(startingBlock, endingBlock uint64) ([]utils.StorageDiff, error) {
+	backFiller.PassedStartingBlock = startingBlock
+	backFiller.PassedEndingBlock = endingBlock
+	return backFiller.StorageDiffsToReturn, backFiller.BackFillErr
+}

libraries/shared/mocks/batch_client.go

@@ -0,0 +1,64 @@
+// VulcanizeDB
+// Copyright © 2019 Vulcanize
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package mocks
+
+import (
+	"encoding/json"
+	"errors"
+
+	"github.com/ethereum/go-ethereum/statediff"
+	"github.com/vulcanize/vulcanizedb/pkg/eth/client"
+)
+
+// BackFillerClient is a mock client for use in backfiller tests
+type BackFillerClient struct {
+	MappedStateDiffAt map[uint64][]byte
+}
+
+// SetReturnDiffAt method to set what statediffs the mock client returns
+func (mc *BackFillerClient) SetReturnDiffAt(height uint64, diffPayload statediff.Payload) error {
+	if mc.MappedStateDiffAt == nil {
+		mc.MappedStateDiffAt = make(map[uint64][]byte)
+	}
+	by, err := json.Marshal(diffPayload)
+	if err != nil {
+		return err
+	}
+	mc.MappedStateDiffAt[height] = by
+	return nil
+}
+
+// BatchCall mockClient method to simulate batch call to geth
+func (mc *BackFillerClient) BatchCall(batch []client.BatchElem) error {
+	if mc.MappedStateDiffAt == nil {
+		return errors.New("mockclient needs to be initialized with statediff payloads and errors")
+	}
+	for _, batchElem := range batch {
+		if len(batchElem.Args) != 1 {
+			return errors.New("expected batch elem to contain single argument")
+		}
+		blockHeight, ok := batchElem.Args[0].(uint64)
+		if !ok {
+			return errors.New("expected batch elem argument to be a uint64")
+		}
+		err := json.Unmarshal(mc.MappedStateDiffAt[blockHeight], batchElem.Result)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}

libraries/shared/mocks/state_diff_fetcher.go

@@ -0,0 +1,48 @@
+// VulcanizeDB
+// Copyright © 2019 Vulcanize
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package mocks
+
+import (
+	"errors"
+
+	"github.com/ethereum/go-ethereum/statediff"
+)
+
+// StateDiffFetcher mock for tests
+type StateDiffFetcher struct {
+	PayloadsToReturn     map[uint64]*statediff.Payload
+	FetchErr             error
+	CalledAtBlockHeights [][]uint64
+}
+
+// SetPayloadsToReturn for tests
+func (fetcher *StateDiffFetcher) SetPayloadsToReturn(payloads map[uint64]*statediff.Payload) {
+	fetcher.PayloadsToReturn = payloads
+}
+
+// FetchStateDiffsAt mock method
+func (fetcher *StateDiffFetcher) FetchStateDiffsAt(blockHeights []uint64) ([]*statediff.Payload, error) {
+	fetcher.CalledAtBlockHeights = append(fetcher.CalledAtBlockHeights, blockHeights)
+	if fetcher.PayloadsToReturn == nil {
+		return nil, errors.New("MockStateDiffFetcher needs to be initialized with payloads to return")
+	}
+	results := make([]*statediff.Payload, 0, len(blockHeights))
+	for _, height := range blockHeights {
+		results = append(results, fetcher.PayloadsToReturn[height])
+	}
+	return results, nil
+}

libraries/shared/mocks/storage_fetcher.go

@@ -18,16 +18,19 @@ package mocks
 
 import "github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 
-type MockStorageFetcher struct {
+// ClosingStorageFetcher is a mock fetcher for use in tests without backfilling
+type ClosingStorageFetcher struct {
 	DiffsToReturn []utils.StorageDiff
 	ErrsToReturn  []error
 }
 
-func NewMockStorageFetcher() *MockStorageFetcher {
+// NewClosingStorageFetcher returns a new ClosingStorageFetcher
-	return &MockStorageFetcher{}
+func NewClosingStorageFetcher() *ClosingStorageFetcher {
+	return &ClosingStorageFetcher{}
 }
 
-func (fetcher *MockStorageFetcher) FetchStorageDiffs(out chan<- utils.StorageDiff, errs chan<- error) {
+// FetchStorageDiffs mock method
+func (fetcher *ClosingStorageFetcher) FetchStorageDiffs(out chan<- utils.StorageDiff, errs chan<- error) {
 	defer close(out)
 	defer close(errs)
 	for _, err := range fetcher.ErrsToReturn {
@@ -37,3 +40,24 @@ func (fetcher *MockStorageFetcher) FetchStorageDiffs(out chan<- utils.StorageDif
 		out <- diff
 	}
 }
+
+// StorageFetcher is a mock fetcher for use in tests with backfilling
+type StorageFetcher struct {
+	DiffsToReturn []utils.StorageDiff
+	ErrsToReturn  []error
+}
+
+// NewStorageFetcher returns a new StorageFetcher
+func NewStorageFetcher() *StorageFetcher {
+	return &StorageFetcher{}
+}
+
+// FetchStorageDiffs mock method
+func (fetcher *StorageFetcher) FetchStorageDiffs(out chan<- utils.StorageDiff, errs chan<- error) {
+	for _, err := range fetcher.ErrsToReturn {
+		errs <- err
+	}
+	for _, diff := range fetcher.DiffsToReturn {
+		out <- diff
+	}
+}

libraries/shared/mocks/storage_queue.go

@@ -20,27 +20,31 @@ import (
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 )
 
+// MockStorageQueue for tests
 type MockStorageQueue struct {
-	AddCalled      bool
+	AddCalled       bool
-	AddError       error
+	AddError        error
-	AddPassedDiff  utils.StorageDiff
+	AddPassedDiffs  []utils.StorageDiff
-	DeleteErr      error
+	DeleteErr       error
-	DeletePassedID int
+	DeletePassedIds []int
-	GetAllErr      error
+	GetAllErr       error
-	DiffsToReturn  []utils.StorageDiff
+	DiffsToReturn   []utils.StorageDiff
 }
 
+// Add mock method
 func (queue *MockStorageQueue) Add(diff utils.StorageDiff) error {
 	queue.AddCalled = true
-	queue.AddPassedDiff = diff
+	queue.AddPassedDiffs = append(queue.AddPassedDiffs, diff)
 	return queue.AddError
 }
 
+// Delete mock method
 func (queue *MockStorageQueue) Delete(id int) error {
-	queue.DeletePassedID = id
+	queue.DeletePassedIds = append(queue.DeletePassedIds, id)
 	return queue.DeleteErr
 }
 
+// GetAll mock method
 func (queue *MockStorageQueue) GetAll() ([]utils.StorageDiff, error) {
 	return queue.DiffsToReturn, queue.GetAllErr
 }

libraries/shared/mocks/storage_transformer.go

@@ -18,26 +18,31 @@ package mocks
 
 import (
 	"github.com/ethereum/go-ethereum/common"
+
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/transformer"
 	"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
 )
 
+// MockStorageTransformer for tests
 type MockStorageTransformer struct {
 	KeccakOfAddress common.Hash
 	ExecuteErr      error
-	PassedDiff      utils.StorageDiff
+	PassedDiffs     []utils.StorageDiff
 }
 
+// Execute mock method
 func (transformer *MockStorageTransformer) Execute(diff utils.StorageDiff) error {
-	transformer.PassedDiff = diff
+	transformer.PassedDiffs = append(transformer.PassedDiffs, diff)
 	return transformer.ExecuteErr
 }
 
+// KeccakContractAddress mock method
 func (transformer *MockStorageTransformer) KeccakContractAddress() common.Hash {
 	return transformer.KeccakOfAddress
 }
 
+// FakeTransformerInitializer mock method
 func (transformer *MockStorageTransformer) FakeTransformerInitializer(db *postgres.DB) transformer.StorageTransformer {
 	return transformer
 }

libraries/shared/repository/address_repository_test.go

@@ -17,14 +17,14 @@
 package repository_test
 
 import (
-	"github.com/vulcanize/vulcanizedb/libraries/shared/repository"
-	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 	"strings"
 
 	"github.com/jmoiron/sqlx"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 
+	"github.com/vulcanize/vulcanizedb/libraries/shared/repository"
+	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 	"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
 	"github.com/vulcanize/vulcanizedb/pkg/fakes"
 	"github.com/vulcanize/vulcanizedb/test_config"

libraries/shared/storage/backfill.go

@@ -17,12 +17,9 @@
 package storage
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
 
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/statediff"
 	"github.com/sirupsen/logrus"
@@ -31,52 +28,39 @@ import (
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 )
 
-// IBackFiller is the backfilling interface
+// BackFiller is the backfilling interface
-type IBackFiller interface {
+type BackFiller interface {
-	BackFill(bfa BackFillerArgs) (map[common.Hash][]utils.StorageDiff, error)
+	BackFill(startingBlock, endingBlock uint64) ([]utils.StorageDiff, error)
 }
 
-// BackFiller is the backfilling struct
+// backFiller is the backfilling struct
-type BackFiller struct {
+type backFiller struct {
-	sdf fetcher.IStateDiffFetcher
+	fetcher fetcher.StateDiffFetcher
 }
 
-// BackFillerArgs are used to pass configuration params to the backfiller
+// NewStorageBackFiller returns a BackFiller
-type BackFillerArgs struct {
+func NewStorageBackFiller(fetcher fetcher.StateDiffFetcher) BackFiller {
-	// mapping of hashed addresses to a list of the storage key hashes we want to collect at that address
+	return &backFiller{
-	WantedStorage map[common.Hash][]common.Hash
+		fetcher: fetcher,
-	StartingBlock uint64
-	EndingBlock   uint64
-}
-
-// NewStorageBackFiller returns a IBackFiller
-func NewStorageBackFiller(bc fetcher.BatchClient) IBackFiller {
-	return &BackFiller{
-		sdf: fetcher.NewStateDiffFetcher(bc),
 	}
 }
 
 // BackFill uses the provided config to fetch and return the state diff at the specified blocknumber
 // StateDiffAt(ctx context.Context, blockNumber uint64) (*Payload, error)
-func (bf *BackFiller) BackFill(bfa BackFillerArgs) (map[common.Hash][]utils.StorageDiff, error) {
+func (bf *backFiller) BackFill(startingBlock, endingBlock uint64) ([]utils.StorageDiff, error) {
-	results := make(map[common.Hash][]utils.StorageDiff, len(bfa.WantedStorage))
+	results := make([]utils.StorageDiff, 0)
-	if bfa.EndingBlock < bfa.StartingBlock {
+	if endingBlock < startingBlock {
 		return nil, errors.New("backfill: ending block number needs to be greater than starting block number")
 	}
-	blockHeights := make([]uint64, 0, bfa.EndingBlock-bfa.StartingBlock+1)
+	blockHeights := make([]uint64, 0, endingBlock-startingBlock+1)
-	for i := bfa.StartingBlock; i <= bfa.EndingBlock; i++ {
+	for i := startingBlock; i <= endingBlock; i++ {
 		blockHeights = append(blockHeights, i)
 	}
-	payloads, err := bf.sdf.FetchStateDiffsAt(blockHeights)
+	payloads, err := bf.fetcher.FetchStateDiffsAt(blockHeights)
 	if err != nil {
 		return nil, err
 	}
 	for _, payload := range payloads {
-		block := new(types.Block)
-		blockDecodeErr := rlp.DecodeBytes(payload.BlockRlp, block)
-		if blockDecodeErr != nil {
-			return nil, blockDecodeErr
-		}
 		stateDiff := new(statediff.StateDiff)
 		stateDiffDecodeErr := rlp.DecodeBytes(payload.StateDiffRlp, stateDiff)
 		if stateDiffDecodeErr != nil {
@@ -84,42 +68,20 @@ func (bf *BackFiller) BackFill(bfa BackFillerArgs) (map[common.Hash][]utils.Stor
 		}
 		accounts := utils.GetAccountsFromDiff(*stateDiff)
 		for _, account := range accounts {
-			if wantedHashedAddress(bfa.WantedStorage, common.BytesToHash(account.Key)) {
+			logrus.Trace(fmt.Sprintf("iterating through %d Storage values on account", len(account.Storage)))
-				logrus.Trace(fmt.Sprintf("iterating through %d Storage values on account", len(account.Storage)))
+			for _, storage := range account.Storage {
-				for _, storage := range account.Storage {
+				diff, formatErr := utils.FromGethStateDiff(account, stateDiff, storage)
-					if wantedHashedStorageKey(bfa.WantedStorage[common.BytesToHash(account.Key)], storage.Key) {
+				if formatErr != nil {
-						diff, formatErr := utils.FromGethStateDiff(account, stateDiff, storage)
+					return nil, formatErr
-						logrus.Trace("adding storage diff to out channel",
-							"keccak of address: ", diff.HashedAddress.Hex(),
-							"block height: ", diff.BlockHeight,
-							"storage key: ", diff.StorageKey.Hex(),
-							"storage value: ", diff.StorageValue.Hex())
-						if formatErr != nil {
-							return nil, formatErr
-						}
-						results[diff.HashedAddress] = append(results[diff.HashedAddress], diff)
-					}
 				}
+				logrus.Trace("adding storage diff to results",
+					"keccak of address: ", diff.HashedAddress.Hex(),
+					"block height: ", diff.BlockHeight,
+					"storage key: ", diff.StorageKey.Hex(),
+					"storage value: ", diff.StorageValue.Hex())
+				results = append(results, diff)
 			}
 		}
 	}
 	return results, nil
 }
-
-func wantedHashedAddress(wantedStorage map[common.Hash][]common.Hash, hashedKey common.Hash) bool {
-	for addrHash := range wantedStorage {
-		if bytes.Equal(addrHash.Bytes(), hashedKey.Bytes()) {
-			return true
-		}
-	}
-	return false
-}
-
-func wantedHashedStorageKey(wantedKeys []common.Hash, keyBytes []byte) bool {
-	for _, key := range wantedKeys {
-		if bytes.Equal(key.Bytes(), keyBytes) {
-			return true
-		}
-	}
-	return false
-}

libraries/shared/storage/backfill_test.go

@@ -18,94 +18,43 @@ package storage_test
 
 import (
 	"bytes"
-	"encoding/json"
-	"errors"
 
-	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/statediff"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 
+	"github.com/vulcanize/vulcanizedb/libraries/shared/mocks"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/test_data"
-	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
 )
 
-type mockClient struct {
-	MappedStateDiffAt map[uint64][]byte
-}
-
-// SetReturnDiffAt method to set what statediffs the mock client returns
-func (mc *mockClient) SetReturnDiffAt(height uint64, diffPayload statediff.Payload) error {
-	if mc.MappedStateDiffAt == nil {
-		mc.MappedStateDiffAt = make(map[uint64][]byte)
-	}
-	by, err := json.Marshal(diffPayload)
-	if err != nil {
-		return err
-	}
-	mc.MappedStateDiffAt[height] = by
-	return nil
-}
-
-// BatchCall mockClient method to simulate batch call to geth
-func (mc *mockClient) BatchCall(batch []client.BatchElem) error {
-	if mc.MappedStateDiffAt == nil {
-		return errors.New("mockclient needs to be initialized with statediff payloads and errors")
-	}
-	for _, batchElem := range batch {
-		if len(batchElem.Args) != 1 {
-			return errors.New("expected batch elem to contain single argument")
-		}
-		blockHeight, ok := batchElem.Args[0].(uint64)
-		if !ok {
-			return errors.New("expected batch elem argument to be a uint64")
-		}
-		err := json.Unmarshal(mc.MappedStateDiffAt[blockHeight], batchElem.Result)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
 var _ = Describe("BackFiller", func() {
 	Describe("BackFill", func() {
 		var (
-			mc         *mockClient
+			fetcher    *mocks.StateDiffFetcher
-			backFiller storage.IBackFiller
+			backFiller storage.BackFiller
 		)
 		BeforeEach(func() {
-			mc = new(mockClient)
+			fetcher = new(mocks.StateDiffFetcher)
-			setDiffAtErr1 := mc.SetReturnDiffAt(test_data.BlockNumber.Uint64(), test_data.MockStatediffPayload)
+			fetcher.SetPayloadsToReturn(map[uint64]*statediff.Payload{
-			Expect(setDiffAtErr1).ToNot(HaveOccurred())
+				test_data.BlockNumber.Uint64():  &test_data.MockStatediffPayload,
-			setDiffAtErr2 := mc.SetReturnDiffAt(test_data.BlockNumber2.Uint64(), test_data.MockStatediffPayload2)
+				test_data.BlockNumber2.Uint64(): &test_data.MockStatediffPayload2,
-			Expect(setDiffAtErr2).ToNot(HaveOccurred())
+			})
-			backFiller = storage.NewStorageBackFiller(mc)
+			backFiller = storage.NewStorageBackFiller(fetcher)
 		})
 		It("Batch calls statediff_stateDiffAt", func() {
-			backFillArgs := storage.BackFillerArgs{
+			backFillStorage, backFillErr := backFiller.BackFill(test_data.BlockNumber.Uint64(), test_data.BlockNumber2.Uint64())
-				WantedStorage: map[common.Hash][]common.Hash{
-					test_data.ContractLeafKey:        {common.BytesToHash(test_data.StorageKey)},
-					test_data.AnotherContractLeafKey: {common.BytesToHash(test_data.StorageKey)},
-				},
-				StartingBlock: test_data.BlockNumber.Uint64(),
-				EndingBlock:   test_data.BlockNumber2.Uint64(),
-			}
-			backFillStorage, backFillErr := backFiller.BackFill(backFillArgs)
 			Expect(backFillErr).ToNot(HaveOccurred())
-			Expect(len(backFillStorage)).To(Equal(2))
+			Expect(len(backFillStorage)).To(Equal(4))
-			Expect(len(backFillStorage[test_data.ContractLeafKey])).To(Equal(1))
-			Expect(len(backFillStorage[test_data.AnotherContractLeafKey])).To(Equal(3))
-			Expect(backFillStorage[test_data.ContractLeafKey][0]).To(Equal(test_data.CreatedExpectedStorageDiff))
 			// Can only rlp encode the slice of diffs as part of a struct
 			// Rlp encoding allows us to compare content of the slices when the order in the slice may vary
 			expectedDiffStruct := struct {
 				diffs []utils.StorageDiff
 			}{
 				[]utils.StorageDiff{
+					test_data.CreatedExpectedStorageDiff,
 					test_data.UpdatedExpectedStorageDiff,
 					test_data.UpdatedExpectedStorageDiff2,
 					test_data.DeletedExpectedStorageDiff,
@@ -116,40 +65,11 @@ var _ = Describe("BackFiller", func() {
 			receivedDiffStruct := struct {
 				diffs []utils.StorageDiff
 			}{
-				backFillStorage[test_data.AnotherContractLeafKey],
+				backFillStorage,
 			}
 			receivedDiffBytes, rlpErr2 := rlp.EncodeToBytes(receivedDiffStruct)
 			Expect(rlpErr2).ToNot(HaveOccurred())
 			Expect(bytes.Equal(expectedDiffBytes, receivedDiffBytes)).To(BeTrue())
 		})
-
-		It("Only returns storage for provided addresses (address hashes)", func() {
-			backFillArgs := storage.BackFillerArgs{
-				WantedStorage: map[common.Hash][]common.Hash{
-					test_data.ContractLeafKey: {common.BytesToHash(test_data.StorageKey)},
-				},
-				StartingBlock: test_data.BlockNumber.Uint64(),
-				EndingBlock:   test_data.BlockNumber2.Uint64(),
-			}
-			backFillStorage, backFillErr := backFiller.BackFill(backFillArgs)
-			Expect(backFillErr).ToNot(HaveOccurred())
-			Expect(len(backFillStorage)).To(Equal(1))
-			Expect(len(backFillStorage[test_data.ContractLeafKey])).To(Equal(1))
-			Expect(len(backFillStorage[test_data.AnotherContractLeafKey])).To(Equal(0))
-			Expect(backFillStorage[test_data.ContractLeafKey][0]).To(Equal(test_data.CreatedExpectedStorageDiff))
-		})
-
-		It("Only returns storage for provided storage keys", func() {
-			backFillArgs := storage.BackFillerArgs{
-				WantedStorage: map[common.Hash][]common.Hash{
-					test_data.ContractLeafKey: nil,
-				},
-				StartingBlock: test_data.BlockNumber.Uint64(),
-				EndingBlock:   test_data.BlockNumber2.Uint64(),
-			}
-			backFillStorage, backFillErr := backFiller.BackFill(backFillArgs)
-			Expect(backFillErr).ToNot(HaveOccurred())
-			Expect(len(backFillStorage)).To(Equal(0))
-		})
 	})
 })

libraries/shared/test_data/statediff.go

@@ -151,6 +151,7 @@ var (
 	}
 
 	CreatedExpectedStorageDiff = utils.StorageDiff{
+		Id:            1333,
 		HashedAddress: common.BytesToHash(ContractLeafKey[:]),
 		BlockHash:     common.HexToHash("0xfa40fbe2d98d98b3363a778d52f2bcd29d6790b9b3f3cab2b167fd12d3550f73"),
 		BlockHeight:   int(BlockNumber.Int64()),
@@ -158,6 +159,7 @@ var (
 		StorageValue:  common.BytesToHash(SmallStorageValue),
 	}
 	UpdatedExpectedStorageDiff = utils.StorageDiff{
+		Id:            1334,
 		HashedAddress: common.BytesToHash(AnotherContractLeafKey[:]),
 		BlockHash:     common.HexToHash("0xfa40fbe2d98d98b3363a778d52f2bcd29d6790b9b3f3cab2b167fd12d3550f73"),
 		BlockHeight:   int(BlockNumber.Int64()),
@@ -165,6 +167,7 @@ var (
 		StorageValue:  common.BytesToHash(LargeStorageValue),
 	}
 	UpdatedExpectedStorageDiff2 = utils.StorageDiff{
+		Id:            1335,
 		HashedAddress: common.BytesToHash(AnotherContractLeafKey[:]),
 		BlockHash:     common.HexToHash("0xfa40fbe2d98d98b3363a778d52f2bcd29d6790b9b3f3cab2b167fd12d3550f73"),
 		BlockHeight:   int(BlockNumber2.Int64()),
@@ -172,6 +175,7 @@ var (
 		StorageValue:  common.BytesToHash(SmallStorageValue),
 	}
 	DeletedExpectedStorageDiff = utils.StorageDiff{
+		Id:            1336,
 		HashedAddress: common.BytesToHash(AnotherContractLeafKey[:]),
 		BlockHash:     common.HexToHash("0xfa40fbe2d98d98b3363a778d52f2bcd29d6790b9b3f3cab2b167fd12d3550f73"),
 		BlockHeight:   int(BlockNumber.Int64()),

libraries/shared/watcher/storage_watcher.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/sirupsen/logrus"
+
 	"github.com/vulcanize/vulcanizedb/libraries/shared/fetcher"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
@@ -31,7 +32,8 @@ import (
 
 type IStorageWatcher interface {
 	AddTransformers(initializers []transformer.StorageTransformerInitializer)
-	Execute(diffsChan chan utils.StorageDiff, errsChan chan error, queueRecheckInterval time.Duration)
+	Execute(queueRecheckInterval time.Duration, backFill bool)
+	BackFill(backFiller storage.BackFiller, minDeploymentBlock int)
 }
 
 type StorageWatcher struct {
@@ -39,6 +41,9 @@ type StorageWatcher struct {
 	StorageFetcher            fetcher.IStorageFetcher
 	Queue                     storage.IStorageQueue
 	KeccakAddressTransformers map[common.Hash]transformer.StorageTransformer // keccak hash of an address => transformer
+	DiffsChan                 chan utils.StorageDiff
+	ErrsChan                  chan error
+	StartingSyncBlockChan     chan int
 }
 
 func NewStorageWatcher(fetcher fetcher.IStorageFetcher, db *postgres.DB) StorageWatcher {
@@ -47,6 +52,9 @@ func NewStorageWatcher(fetcher fetcher.IStorageFetcher, db *postgres.DB) Storage
 	return StorageWatcher{
 		db:                        db,
 		StorageFetcher:            fetcher,
+		DiffsChan:                 make(chan utils.StorageDiff),
+		ErrsChan:                  make(chan error),
+		StartingSyncBlockChan:     make(chan int),
 		Queue:                     queue,
 		KeccakAddressTransformers: transformers,
 	}
@@ -59,14 +67,33 @@ func (storageWatcher StorageWatcher) AddTransformers(initializers []transformer.
 	}
 }
 
-func (storageWatcher StorageWatcher) Execute(diffsChan chan utils.StorageDiff, errsChan chan error, queueRecheckInterval time.Duration) {
+// BackFill configures the StorageWatcher to backfill missed storage diffs using a modified archival geth client
+func (storageWatcher StorageWatcher) BackFill(backFiller storage.BackFiller, minDeploymentBlock int) {
+	// need to learn which block to perform the backfill process up to
+	// this blocks until the Execute process sends us the first block number it sees
+	startingSyncBlock := <-storageWatcher.StartingSyncBlockChan
+	backFilledDiffs, err := backFiller.BackFill(uint64(minDeploymentBlock), uint64(startingSyncBlock))
+	if err != nil {
+		storageWatcher.ErrsChan <- err
+	}
+	for _, storageDiff := range backFilledDiffs {
+		storageWatcher.DiffsChan <- storageDiff
+	}
+}
+
+func (storageWatcher StorageWatcher) Execute(queueRecheckInterval time.Duration, backFill bool) {
 	ticker := time.NewTicker(queueRecheckInterval)
-	go storageWatcher.StorageFetcher.FetchStorageDiffs(diffsChan, errsChan)
+	go storageWatcher.StorageFetcher.FetchStorageDiffs(storageWatcher.DiffsChan, storageWatcher.ErrsChan)
+	start := true
 	for {
 		select {
-		case fetchErr := <-errsChan:
+		case fetchErr := <-storageWatcher.ErrsChan:
 			logrus.Warn(fmt.Sprintf("error fetching storage diffs: %s", fetchErr))
-		case diff := <-diffsChan:
+		case diff := <-storageWatcher.DiffsChan:
+			if start && backFill {
+				storageWatcher.StartingSyncBlockChan <- diff.BlockHeight - 1
+				start = false
+			}
 			storageWatcher.processRow(diff)
 		case <-ticker.C:
 			storageWatcher.processQueue()

libraries/shared/watcher/storage_watcher_test.go

@@ -22,11 +22,14 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rlp"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	"github.com/sirupsen/logrus"
+
 	"github.com/vulcanize/vulcanizedb/libraries/shared/mocks"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
+	"github.com/vulcanize/vulcanizedb/libraries/shared/test_data"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/transformer"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/watcher"
 	"github.com/vulcanize/vulcanizedb/pkg/fakes"
@@ -38,7 +41,7 @@ var _ = Describe("Storage Watcher", func() {
 		It("adds transformers", func() {
 			fakeHashedAddress := utils.HexToKeccak256Hash("0x12345")
 			fakeTransformer := &mocks.MockStorageTransformer{KeccakOfAddress: fakeHashedAddress}
-			w := watcher.NewStorageWatcher(mocks.NewMockStorageFetcher(), test_config.NewTestDB(test_config.NewTestNode()))
+			w := watcher.NewStorageWatcher(mocks.NewClosingStorageFetcher(), test_config.NewTestDB(test_config.NewTestNode()))
 
 			w.AddTransformers([]transformer.StorageTransformerInitializer{fakeTransformer.FakeTransformerInitializer})
 
@@ -48,21 +51,17 @@ var _ = Describe("Storage Watcher", func() {
 
 	Describe("Execute", func() {
 		var (
-			errs            chan error
+			mockFetcher     *mocks.ClosingStorageFetcher
-			mockFetcher     *mocks.MockStorageFetcher
 			mockQueue       *mocks.MockStorageQueue
 			mockTransformer *mocks.MockStorageTransformer
 			csvDiff         utils.StorageDiff
-			diffs           chan utils.StorageDiff
 			storageWatcher  watcher.StorageWatcher
 			hashedAddress   common.Hash
 		)
 
 		BeforeEach(func() {
-			errs = make(chan error)
-			diffs = make(chan utils.StorageDiff)
 			hashedAddress = utils.HexToKeccak256Hash("0x0123456789abcdef")
-			mockFetcher = mocks.NewMockStorageFetcher()
+			mockFetcher = mocks.NewClosingStorageFetcher()
 			mockQueue = &mocks.MockStorageQueue{}
 			mockTransformer = &mocks.MockStorageTransformer{KeccakOfAddress: hashedAddress}
 			csvDiff = utils.StorageDiff{
@@ -85,7 +84,7 @@ var _ = Describe("Storage Watcher", func() {
 			defer os.Remove(tempFile.Name())
 			logrus.SetOutput(tempFile)
 
-			go storageWatcher.Execute(diffs, errs, time.Hour)
+			go storageWatcher.Execute(time.Hour, false)
 
 			Eventually(func() (string, error) {
 				logContent, err := ioutil.ReadFile(tempFile.Name())
@@ -103,25 +102,28 @@ var _ = Describe("Storage Watcher", func() {
 			})
 
 			It("executes transformer for recognized storage diff", func(done Done) {
-				go storageWatcher.Execute(diffs, errs, time.Hour)
+				go storageWatcher.Execute(time.Hour, false)
 
-				Eventually(func() utils.StorageDiff {
+				Eventually(func() []utils.StorageDiff {
-					return mockTransformer.PassedDiff
+					return mockTransformer.PassedDiffs
-				}).Should(Equal(csvDiff))
+				}).Should(Equal([]utils.StorageDiff{csvDiff}))
 				close(done)
 			})
 
 			It("queues diff for later processing if transformer execution fails", func(done Done) {
 				mockTransformer.ExecuteErr = fakes.FakeError
 
-				go storageWatcher.Execute(diffs, errs, time.Hour)
+				go storageWatcher.Execute(time.Hour, false)
 
-				Expect(<-errs).To(BeNil())
+				Expect(<-storageWatcher.ErrsChan).To(BeNil())
 				Eventually(func() bool {
 					return mockQueue.AddCalled
 				}).Should(BeTrue())
 				Eventually(func() utils.StorageDiff {
-					return mockQueue.AddPassedDiff
+					if len(mockQueue.AddPassedDiffs) > 0 {
+						return mockQueue.AddPassedDiffs[0]
+					}
+					return utils.StorageDiff{}
 				}).Should(Equal(csvDiff))
 				close(done)
 			})
@@ -134,7 +136,7 @@ var _ = Describe("Storage Watcher", func() {
 				defer os.Remove(tempFile.Name())
 				logrus.SetOutput(tempFile)
 
-				go storageWatcher.Execute(diffs, errs, time.Hour)
+				go storageWatcher.Execute(time.Hour, false)
 
 				Eventually(func() bool {
 					return mockQueue.AddCalled
@@ -156,19 +158,25 @@ var _ = Describe("Storage Watcher", func() {
 			})
 
 			It("executes transformer for storage diff", func(done Done) {
-				go storageWatcher.Execute(diffs, errs, time.Nanosecond)
+				go storageWatcher.Execute(time.Nanosecond, false)
 
 				Eventually(func() utils.StorageDiff {
-					return mockTransformer.PassedDiff
+					if len(mockTransformer.PassedDiffs) > 0 {
+						return mockTransformer.PassedDiffs[0]
+					}
+					return utils.StorageDiff{}
 				}).Should(Equal(csvDiff))
 				close(done)
 			})
 
 			It("deletes diff from queue if transformer execution successful", func(done Done) {
-				go storageWatcher.Execute(diffs, errs, time.Nanosecond)
+				go storageWatcher.Execute(time.Nanosecond, false)
 
 				Eventually(func() int {
-					return mockQueue.DeletePassedID
+					if len(mockQueue.DeletePassedIds) > 0 {
+						return mockQueue.DeletePassedIds[0]
+					}
+					return 0
 				}).Should(Equal(csvDiff.ID))
 				close(done)
 			})
@@ -180,7 +188,7 @@ var _ = Describe("Storage Watcher", func() {
 				defer os.Remove(tempFile.Name())
 				logrus.SetOutput(tempFile)
 
-				go storageWatcher.Execute(diffs, errs, time.Nanosecond)
+				go storageWatcher.Execute(time.Nanosecond, false)
 
 				Eventually(func() (string, error) {
 					logContent, err := ioutil.ReadFile(tempFile.Name())
@@ -196,10 +204,13 @@ var _ = Describe("Storage Watcher", func() {
 				}
 				mockQueue.DiffsToReturn = []utils.StorageDiff{obsoleteDiff}
 
-				go storageWatcher.Execute(diffs, errs, time.Nanosecond)
+				go storageWatcher.Execute(time.Nanosecond, false)
 
 				Eventually(func() int {
-					return mockQueue.DeletePassedID
+					if len(mockQueue.DeletePassedIds) > 0 {
+						return mockQueue.DeletePassedIds[0]
+					}
+					return 0
 				}).Should(Equal(obsoleteDiff.ID))
 				close(done)
 			})
@@ -216,7 +227,127 @@ var _ = Describe("Storage Watcher", func() {
 				defer os.Remove(tempFile.Name())
 				logrus.SetOutput(tempFile)
 
-				go storageWatcher.Execute(diffs, errs, time.Nanosecond)
+				go storageWatcher.Execute(time.Nanosecond, false)
+
+				Eventually(func() (string, error) {
+					logContent, err := ioutil.ReadFile(tempFile.Name())
+					return string(logContent), err
+				}).Should(ContainSubstring(fakes.FakeError.Error()))
+				close(done)
+			})
+		})
+	})
+
+	Describe("BackFill", func() {
+		var (
+			mockFetcher     *mocks.StorageFetcher
+			mockBackFiller  *mocks.BackFiller
+			mockQueue       *mocks.MockStorageQueue
+			mockTransformer *mocks.MockStorageTransformer
+			csvDiff         utils.StorageDiff
+			storageWatcher  watcher.StorageWatcher
+			hashedAddress   common.Hash
+		)
+
+		BeforeEach(func() {
+			mockBackFiller = new(mocks.BackFiller)
+			mockBackFiller.SetStorageDiffsToReturn([]utils.StorageDiff{
+				test_data.CreatedExpectedStorageDiff,
+				test_data.UpdatedExpectedStorageDiff,
+				test_data.UpdatedExpectedStorageDiff2,
+				test_data.DeletedExpectedStorageDiff})
+			hashedAddress = utils.HexToKeccak256Hash("0x0123456789abcdef")
+			mockFetcher = mocks.NewStorageFetcher()
+			mockQueue = &mocks.MockStorageQueue{}
+			mockTransformer = &mocks.MockStorageTransformer{KeccakOfAddress: hashedAddress}
+			csvDiff = utils.StorageDiff{
+				ID:            1337,
+				HashedAddress: hashedAddress,
+				BlockHash:     common.HexToHash("0xfedcba9876543210"),
+				BlockHeight:   int(test_data.BlockNumber2.Int64()) + 1,
+				StorageKey:    common.HexToHash("0xabcdef1234567890"),
+				StorageValue:  common.HexToHash("0x9876543210abcdef"),
+			}
+		})
+
+		Describe("transforming streamed and backfilled queued storage diffs", func() {
+			BeforeEach(func() {
+				mockFetcher.DiffsToReturn = []utils.StorageDiff{csvDiff}
+				mockQueue.DiffsToReturn = []utils.StorageDiff{csvDiff,
+					test_data.CreatedExpectedStorageDiff,
+					test_data.UpdatedExpectedStorageDiff,
+					test_data.UpdatedExpectedStorageDiff2,
+					test_data.DeletedExpectedStorageDiff}
+				storageWatcher = watcher.NewStorageWatcher(mockFetcher, test_config.NewTestDB(test_config.NewTestNode()))
+				storageWatcher.Queue = mockQueue
+				storageWatcher.AddTransformers([]transformer.StorageTransformerInitializer{mockTransformer.FakeTransformerInitializer})
+			})
+
+			It("executes transformer for storage diffs", func(done Done) {
+				go storageWatcher.BackFill(mockBackFiller, int(test_data.BlockNumber.Uint64()))
+				go storageWatcher.Execute(time.Nanosecond, true)
+				expectedDiffsStruct := struct {
+					diffs []utils.StorageDiff
+				}{
+					[]utils.StorageDiff{
+						csvDiff,
+						test_data.CreatedExpectedStorageDiff,
+						test_data.UpdatedExpectedStorageDiff,
+						test_data.UpdatedExpectedStorageDiff2,
+						test_data.DeletedExpectedStorageDiff,
+					},
+				}
+				expectedDiffsBytes, rlpErr1 := rlp.EncodeToBytes(expectedDiffsStruct)
+				Expect(rlpErr1).ToNot(HaveOccurred())
+				Eventually(func() []byte {
+					diffsStruct := struct {
+						diffs []utils.StorageDiff
+					}{
+						mockTransformer.PassedDiffs,
+					}
+					diffsBytes, rlpErr2 := rlp.EncodeToBytes(diffsStruct)
+					Expect(rlpErr2).ToNot(HaveOccurred())
+					return diffsBytes
+				}).Should(Equal(expectedDiffsBytes))
+				close(done)
+			})
+
+			It("deletes diffs from queue if transformer execution is successful", func(done Done) {
+				go storageWatcher.Execute(time.Nanosecond, false)
+				expectedIdsStruct := struct {
+					diffs []int
+				}{
+					[]int{
+						csvDiff.ID,
+						test_data.CreatedExpectedStorageDiff.ID,
+						test_data.UpdatedExpectedStorageDiff.ID,
+						test_data.UpdatedExpectedStorageDiff2.ID,
+						test_data.DeletedExpectedStorageDiff.ID,
+					},
+				}
+				expectedIdsBytes, rlpErr1 := rlp.EncodeToBytes(expectedIdsStruct)
+				Expect(rlpErr1).ToNot(HaveOccurred())
+				Eventually(func() []byte {
+					idsStruct := struct {
+						diffs []int
+					}{
+						mockQueue.DeletePassedIds,
+					}
+					idsBytes, rlpErr2 := rlp.EncodeToBytes(idsStruct)
+					Expect(rlpErr2).ToNot(HaveOccurred())
+					return idsBytes
+				}).Should(Equal(expectedIdsBytes))
+				close(done)
+			})
+
+			It("logs error if deleting persisted diff fails", func(done Done) {
+				mockQueue.DeleteErr = fakes.FakeError
+				tempFile, fileErr := ioutil.TempFile("", "log")
+				Expect(fileErr).NotTo(HaveOccurred())
+				defer os.Remove(tempFile.Name())
+				logrus.SetOutput(tempFile)
+
+				go storageWatcher.Execute(time.Nanosecond, false)
 
 				Eventually(func() (string, error) {
 					logContent, err := ioutil.ReadFile(tempFile.Name())