factor our state diff fetcher for more general use (e.g. by the super node)

libraries/shared/fetcher/state_diff_fetcher.go

@@ -0,0 +1,72 @@
+// 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 fetcher
+
+import (
+	"github.com/ethereum/go-ethereum/statediff"
+
+	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
+)
+
+// IStateDiffFetcher is the state diff fetching interface
+type IStateDiffFetcher interface {
+	FetchStateDiffsAt(blockHeights []uint64) ([]*statediff.Payload, error)
+}
+
+// BatchClient is an interface to a batch-fetching geth rpc client; created to allow mock insertion
+type BatchClient interface {
+	BatchCall(batch []client.BatchElem) error
+}
+
+// StateDiffFetcher is the state diff fetching struct
+type StateDiffFetcher struct {
+	client BatchClient
+}
+
+const method = "statediff_stateDiffAt"
+
+// NewStateDiffFetcher returns a IStateDiffFetcher
+func NewStateDiffFetcher(bc BatchClient) IStateDiffFetcher {
+	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) {
+	batch := make([]client.BatchElem, 0)
+	for _, height := range blockHeights {
+		batch = append(batch, client.BatchElem{
+			Method: method,
+			Args:   []interface{}{height},
+			Result: new(statediff.Payload),
+		})
+	}
+	batchErr := sdf.client.BatchCall(batch)
+	if batchErr != nil {
+		return nil, batchErr
+	}
+	results := make([]*statediff.Payload, 0, len(blockHeights))
+	for _, batchElem := range batch {
+		if batchElem.Error != nil {
+			return nil, batchElem.Error
+		}
+		results = append(results, batchElem.Result.(*statediff.Payload))
+	}
+	return results, nil
+}

libraries/shared/fetcher/state_diff_fetcher_test.go

@@ -0,0 +1,117 @@
+// 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 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/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
+			stateDiffFetcher fetcher.IStateDiffFetcher
+		)
+		BeforeEach(func() {
+			mc = new(mockClient)
+			setDiffAtErr1 := mc.SetReturnDiffAt(test_data.BlockNumber.Uint64(), test_data.MockStatediffPayload)
+			Expect(setDiffAtErr1).ToNot(HaveOccurred())
+			setDiffAtErr2 := mc.SetReturnDiffAt(test_data.BlockNumber2.Uint64(), test_data.MockStatediffPayload2)
+			Expect(setDiffAtErr2).ToNot(HaveOccurred())
+			stateDiffFetcher = fetcher.NewStateDiffFetcher(mc)
+		})
+		It("Batch calls statediff_stateDiffAt", func() {
+			blockHeights := []uint64{
+				test_data.BlockNumber.Uint64(),
+				test_data.BlockNumber2.Uint64(),
+			}
+			stateDiffPayloads, fetchErr := stateDiffFetcher.FetchStateDiffsAt(blockHeights)
+			Expect(fetchErr).ToNot(HaveOccurred())
+			Expect(len(stateDiffPayloads)).To(Equal(2))
+			// 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
+			expectedPayloadsStruct := struct {
+				payloads []*statediff.Payload
+			}{
+				[]*statediff.Payload{
+					&test_data.MockStatediffPayload,
+					&test_data.MockStatediffPayload2,
+				},
+			}
+			expectedPayloadsBytes, rlpErr1 := rlp.EncodeToBytes(expectedPayloadsStruct)
+			Expect(rlpErr1).ToNot(HaveOccurred())
+			receivedPayloadsStruct := struct {
+				payloads []*statediff.Payload
+			}{
+				stateDiffPayloads,
+			}
+			receivedPayloadsBytes, rlpErr2 := rlp.EncodeToBytes(receivedPayloadsStruct)
+			Expect(rlpErr2).ToNot(HaveOccurred())
+			Expect(bytes.Equal(expectedPayloadsBytes, receivedPayloadsBytes)).To(BeTrue())
+		})
+	})
+})

libraries/shared/storage/backfill.go

@@ -27,8 +27,8 @@ import (
 	"github.com/ethereum/go-ethereum/statediff"
 	"github.com/sirupsen/logrus"
 
+	"github.com/vulcanize/vulcanizedb/libraries/shared/fetcher"
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
-	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
 )
 
 // IBackFiller is the backfilling interface
@@ -36,14 +36,9 @@ type IBackFiller interface {
 	BackFill(bfa BackFillerArgs) (map[common.Hash][]utils.StorageDiff, error)
 }
 
-// BatchClient is an interface to a batch-fetching geth rpc client; created to allow mock insertion
-type BatchClient interface {
-	BatchCall(batch []client.BatchElem) error
-}
-
 // BackFiller is the backfilling struct
 type BackFiller struct {
-	client BatchClient
+	sdf fetcher.IStateDiffFetcher
 }
 
 // BackFillerArgs are used to pass configuration params to the backfiller
@@ -54,12 +49,10 @@ type BackFillerArgs struct {
 	EndingBlock   uint64
 }
 
-const method = "statediff_stateDiffAt"
-
 // NewStorageBackFiller returns a IBackFiller
-func NewStorageBackFiller(bc BatchClient) IBackFiller {
+func NewStorageBackFiller(bc fetcher.BatchClient) IBackFiller {
 	return &BackFiller{
-		client: bc,
+		sdf: fetcher.NewStateDiffFetcher(bc),
 	}
 }
 
@@ -70,23 +63,15 @@ func (bf *BackFiller) BackFill(bfa BackFillerArgs) (map[common.Hash][]utils.Stor
 	if bfa.EndingBlock < bfa.StartingBlock {
 		return nil, errors.New("backfill: ending block number needs to be greater than starting block number")
 	}
-	batch := make([]client.BatchElem, 0)
+	blockHeights := make([]uint64, 0, bfa.EndingBlock-bfa.StartingBlock+1)
 	for i := bfa.StartingBlock; i <= bfa.EndingBlock; i++ {
-		batch = append(batch, client.BatchElem{
-			Method: method,
-			Args:   []interface{}{i},
-			Result: new(statediff.Payload),
-		})
+		blockHeights = append(blockHeights, i)
 	}
-	batchErr := bf.client.BatchCall(batch)
-	if batchErr != nil {
-		return nil, batchErr
+	payloads, err := bf.sdf.FetchStateDiffsAt(blockHeights)
+	if err != nil {
+		return nil, err
 	}
-	for _, batchElem := range batch {
-		payload := batchElem.Result.(*statediff.Payload)
-		if batchElem.Error != nil {
-			return nil, batchElem.Error
-		}
+	for _, payload := range payloads {
 		block := new(types.Block)
 		blockDecodeErr := rlp.DecodeBytes(payload.BlockRlp, block)
 		if blockDecodeErr != nil {