Makefile

@@ -52,6 +52,7 @@ ios:
 
 .PHONY: statedifftest
 statedifftest: | $(GOOSE)
+	go get github.com/stretchr/testify/assert@v1.7.0
 	MODE=statediff go test ./statediff/... -v
 
 test: all

docker-compose.yml

@@ -3,7 +3,7 @@ version: '3.2'
 services:
   ipld-eth-db:
     restart: always
-    image: vulcanize/ipld-eth-db:v0.2.0
+    image: vulcanize/ipld-eth-db:v2.1.1
     environment:
       POSTGRES_USER: "vdbm"
       POSTGRES_DB: "vulcanize_public"

go.mod

@@ -68,6 +68,7 @@ require (
 	github.com/status-im/keycard-go v0.0.0-20190316090335-8537d3370df4
 	github.com/stretchr/testify v1.7.0
 	github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7
+	github.com/thoas/go-funk v0.9.1
 	github.com/tklauser/go-sysconf v0.3.5 // indirect
 	github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef
 	golang.org/x/crypto v0.0.0-20210513164829-c07d793c2f9a

go.sum

@@ -470,6 +470,8 @@ github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5Cc
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7 h1:epCh84lMvA70Z7CTTCmYQn2CKbY8j86K7/FAIr141uY=
 github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7/go.mod h1:q4W45IWZaF22tdD+VEXcAWRA037jwmWEB5VWYORlTpc=
+github.com/thoas/go-funk v0.9.1 h1:O549iLZqPpTUQ10ykd26sZhzD+rmR5pWhuElrhbC20M=
+github.com/thoas/go-funk v0.9.1/go.mod h1:+IWnUfUmFO1+WVYQWQtIJHeRRdaIyyYglZN7xzUPe4Q=
 github.com/tinylib/msgp v1.0.2/go.mod h1:+d+yLhGm8mzTaHzB+wgMYrodPfmZrzkirds8fDWklFE=
 github.com/tklauser/go-sysconf v0.3.5 h1:uu3Xl4nkLzQfXNsWn15rPc/HQCJKObbt1dKJeWp3vU4=
 github.com/tklauser/go-sysconf v0.3.5/go.mod h1:MkWzOF4RMCshBAMXuhXJs64Rte09mITnppBXY/rYEFI=

statediff/README.md

@@ -106,15 +106,13 @@ type Params struct {
 	IncludeTD                bool
 	IncludeCode              bool
 	WatchedAddresses         []common.Address
-	WatchedStorageSlots      []common.Hash
 }
 ```
 
 Using these params we can tell the service whether to include state and/or storage intermediate nodes; whether
 to include the associated block (header, uncles, and transactions); whether to include the associated receipts;
 whether to include the total difficulty for this block; whether to include the set of code hashes and code for
-contracts deployed in this block; whether to limit the diffing process to a list of specific addresses; and/or
+contracts deployed in this block; whether to limit the diffing process to a list of specific addresses.
-whether to limit the diffing process to a list of specific storage slot keys.
 
 #### Subscription endpoint
 A websocket supporting RPC endpoint is exposed for subscribing to state diff `StateObjects` that come off the head of the chain while the geth node syncs.

statediff/api.go

@@ -149,3 +149,8 @@ func (api *PublicStateDiffAPI) WriteStateDiffAt(ctx context.Context, blockNumber
 func (api *PublicStateDiffAPI) WriteStateDiffFor(ctx context.Context, blockHash common.Hash, params Params) error {
 	return api.sds.WriteStateDiffFor(blockHash, params)
 }
+
+// WatchAddress changes the list of watched addresses to which the direct indexing is restricted according to given operation
+func (api *PublicStateDiffAPI) WatchAddress(operation OperationType, args []WatchAddressArg) error {
+	return api.sds.WatchAddress(operation, args)
+}

statediff/builder.go

@@ -123,7 +123,7 @@ func (sdb *builder) buildStateTrie(it trie.NodeIterator) ([]StateNode, []CodeAnd
 			node.LeafKey = leafKey
 			if !bytes.Equal(account.CodeHash, nullCodeHash) {
 				var storageNodes []StorageNode
-				err := sdb.buildStorageNodesEventual(account.Root, nil, true, storageNodeAppender(&storageNodes))
+				err := sdb.buildStorageNodesEventual(account.Root, true, storageNodeAppender(&storageNodes))
 				if err != nil {
 					return nil, nil, fmt.Errorf("failed building eventual storage diffs for account %+v\r\nerror: %v", account, err)
 				}
@@ -202,7 +202,7 @@ func (sdb *builder) buildStateDiffWithIntermediateStateNodes(args StateRoots, pa
 	// a map of their leafkey to all the accounts that were touched and exist at A
 	diffAccountsAtA, err := sdb.deletedOrUpdatedState(
 		oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}),
-		diffPathsAtB, output)
+		diffPathsAtB, params.watchedAddressesLeafKeys, output)
 	if err != nil {
 		return fmt.Errorf("error collecting deletedOrUpdatedNodes: %v", err)
 	}
@@ -220,12 +220,12 @@ func (sdb *builder) buildStateDiffWithIntermediateStateNodes(args StateRoots, pa
 	// build the diff nodes for the updated accounts using the mappings at both A and B as directed by the keys found as the intersection of the two
 	err = sdb.buildAccountUpdates(
 		diffAccountsAtB, diffAccountsAtA, updatedKeys,
-		params.WatchedStorageSlots, params.IntermediateStorageNodes, output)
+		params.IntermediateStorageNodes, output)
 	if err != nil {
 		return fmt.Errorf("error building diff for updated accounts: %v", err)
 	}
 	// build the diff nodes for created accounts
-	err = sdb.buildAccountCreations(diffAccountsAtB, params.WatchedStorageSlots, params.IntermediateStorageNodes, output, codeOutput)
+	err = sdb.buildAccountCreations(diffAccountsAtB, params.IntermediateStorageNodes, output, codeOutput)
 	if err != nil {
 		return fmt.Errorf("error building diff for created accounts: %v", err)
 	}
@@ -247,7 +247,7 @@ func (sdb *builder) buildStateDiffWithoutIntermediateStateNodes(args StateRoots,
 	// and a slice of all the paths for the nodes in both of the above sets
 	diffAccountsAtB, diffPathsAtB, err := sdb.createdAndUpdatedState(
 		oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}),
-		params.WatchedAddresses)
+		params.watchedAddressesLeafKeys)
 	if err != nil {
 		return fmt.Errorf("error collecting createdAndUpdatedNodes: %v", err)
 	}
@@ -256,7 +256,7 @@ func (sdb *builder) buildStateDiffWithoutIntermediateStateNodes(args StateRoots,
 	// a map of their leafkey to all the accounts that were touched and exist at A
 	diffAccountsAtA, err := sdb.deletedOrUpdatedState(
 		oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}),
-		diffPathsAtB, output)
+		diffPathsAtB, params.watchedAddressesLeafKeys, output)
 	if err != nil {
 		return fmt.Errorf("error collecting deletedOrUpdatedNodes: %v", err)
 	}
@@ -274,12 +274,12 @@ func (sdb *builder) buildStateDiffWithoutIntermediateStateNodes(args StateRoots,
 	// build the diff nodes for the updated accounts using the mappings at both A and B as directed by the keys found as the intersection of the two
 	err = sdb.buildAccountUpdates(
 		diffAccountsAtB, diffAccountsAtA, updatedKeys,
-		params.WatchedStorageSlots, params.IntermediateStorageNodes, output)
+		params.IntermediateStorageNodes, output)
 	if err != nil {
 		return fmt.Errorf("error building diff for updated accounts: %v", err)
 	}
 	// build the diff nodes for created accounts
-	err = sdb.buildAccountCreations(diffAccountsAtB, params.WatchedStorageSlots, params.IntermediateStorageNodes, output, codeOutput)
+	err = sdb.buildAccountCreations(diffAccountsAtB, params.IntermediateStorageNodes, output, codeOutput)
 	if err != nil {
 		return fmt.Errorf("error building diff for created accounts: %v", err)
 	}
@@ -289,7 +289,7 @@ func (sdb *builder) buildStateDiffWithoutIntermediateStateNodes(args StateRoots,
 // createdAndUpdatedState returns
 // a mapping of their leafkeys to all the accounts that exist in a different state at B than A
 // and a slice of the paths for all of the nodes included in both
-func (sdb *builder) createdAndUpdatedState(a, b trie.NodeIterator, watchedAddresses []common.Address) (AccountMap, map[string]bool, error) {
+func (sdb *builder) createdAndUpdatedState(a, b trie.NodeIterator, watchedAddressesLeafKeys map[common.Hash]struct{}) (AccountMap, map[string]bool, error) {
 	diffPathsAtB := make(map[string]bool)
 	diffAcountsAtB := make(AccountMap)
 	it, _ := trie.NewDifferenceIterator(a, b)
@@ -313,7 +313,7 @@ func (sdb *builder) createdAndUpdatedState(a, b trie.NodeIterator, watchedAddres
 			valueNodePath := append(node.Path, partialPath...)
 			encodedPath := trie.HexToCompact(valueNodePath)
 			leafKey := encodedPath[1:]
-			if isWatchedAddress(watchedAddresses, leafKey) {
+			if isWatchedAddress(watchedAddressesLeafKeys, leafKey) {
 				diffAcountsAtB[common.Bytes2Hex(leafKey)] = accountWrapper{
 					NodeType:  node.NodeType,
 					Path:      node.Path,
@@ -386,7 +386,7 @@ func (sdb *builder) createdAndUpdatedStateWithIntermediateNodes(a, b trie.NodeIt
 
 // deletedOrUpdatedState returns a slice of all the pathes that are emptied at B
 // and a mapping of their leafkeys to all the accounts that exist in a different state at A than B
-func (sdb *builder) deletedOrUpdatedState(a, b trie.NodeIterator, diffPathsAtB map[string]bool, output StateNodeSink) (AccountMap, error) {
+func (sdb *builder) deletedOrUpdatedState(a, b trie.NodeIterator, diffPathsAtB map[string]bool, watchedAddressesLeafKeys map[common.Hash]struct{}, output StateNodeSink) (AccountMap, error) {
 	diffAccountAtA := make(AccountMap)
 	it, _ := trie.NewDifferenceIterator(b, a)
 	for it.Next(true) {
@@ -409,6 +409,7 @@ func (sdb *builder) deletedOrUpdatedState(a, b trie.NodeIterator, diffPathsAtB m
 			valueNodePath := append(node.Path, partialPath...)
 			encodedPath := trie.HexToCompact(valueNodePath)
 			leafKey := encodedPath[1:]
+			if isWatchedAddress(watchedAddressesLeafKeys, leafKey) {
 				diffAccountAtA[common.Bytes2Hex(leafKey)] = accountWrapper{
 					NodeType:  node.NodeType,
 					Path:      node.Path,
@@ -429,6 +430,7 @@ func (sdb *builder) deletedOrUpdatedState(a, b trie.NodeIterator, diffPathsAtB m
 						return nil, err
 					}
 				}
+			}
 		case Extension, Branch:
 			// if this node's path did not show up in diffPathsAtB
 			// that means the node at this path was deleted (or moved) in B
@@ -454,8 +456,7 @@ func (sdb *builder) deletedOrUpdatedState(a, b trie.NodeIterator, diffPathsAtB m
 // to generate the statediff node objects for all of the accounts that existed at both A and B but in different states
 // needs to be called before building account creations and deletions as this mutates
 // those account maps to remove the accounts which were updated
-func (sdb *builder) buildAccountUpdates(creations, deletions AccountMap, updatedKeys []string,
+func (sdb *builder) buildAccountUpdates(creations, deletions AccountMap, updatedKeys []string, intermediateStorageNodes bool, output StateNodeSink) error {
-	watchedStorageKeys []common.Hash, intermediateStorageNodes bool, output StateNodeSink) error {
 	var err error
 	for _, key := range updatedKeys {
 		createdAcc := creations[key]
@@ -465,7 +466,7 @@ func (sdb *builder) buildAccountUpdates(creations, deletions AccountMap, updated
 			oldSR := deletedAcc.Account.Root
 			newSR := createdAcc.Account.Root
 			err = sdb.buildStorageNodesIncremental(
-				oldSR, newSR, watchedStorageKeys, intermediateStorageNodes,
+				oldSR, newSR, intermediateStorageNodes,
 				storageNodeAppender(&storageDiffs))
 			if err != nil {
 				return fmt.Errorf("failed building incremental storage diffs for account with leafkey %s\r\nerror: %v", key, err)
@@ -489,7 +490,7 @@ func (sdb *builder) buildAccountUpdates(creations, deletions AccountMap, updated
 
 // buildAccountCreations returns the statediff node objects for all the accounts that exist at B but not at A
 // it also returns the code and codehash for created contract accounts
-func (sdb *builder) buildAccountCreations(accounts AccountMap, watchedStorageKeys []common.Hash, intermediateStorageNodes bool, output StateNodeSink, codeOutput CodeSink) error {
+func (sdb *builder) buildAccountCreations(accounts AccountMap, intermediateStorageNodes bool, output StateNodeSink, codeOutput CodeSink) error {
 	for _, val := range accounts {
 		diff := StateNode{
 			NodeType:  val.NodeType,
@@ -500,7 +501,7 @@ func (sdb *builder) buildAccountCreations(accounts AccountMap, watchedStorageKey
 		if !bytes.Equal(val.Account.CodeHash, nullCodeHash) {
 			// For contract creations, any storage node contained is a diff
 			var storageDiffs []StorageNode
-			err := sdb.buildStorageNodesEventual(val.Account.Root, watchedStorageKeys, intermediateStorageNodes, storageNodeAppender(&storageDiffs))
+			err := sdb.buildStorageNodesEventual(val.Account.Root, intermediateStorageNodes, storageNodeAppender(&storageDiffs))
 			if err != nil {
 				return fmt.Errorf("failed building eventual storage diffs for node %x\r\nerror: %v", val.Path, err)
 			}
@@ -528,7 +529,7 @@ func (sdb *builder) buildAccountCreations(accounts AccountMap, watchedStorageKey
 
 // buildStorageNodesEventual builds the storage diff node objects for a created account
 // i.e. it returns all the storage nodes at this state, since there is no previous state
-func (sdb *builder) buildStorageNodesEventual(sr common.Hash, watchedStorageKeys []common.Hash, intermediateNodes bool, output StorageNodeSink) error {
+func (sdb *builder) buildStorageNodesEventual(sr common.Hash, intermediateNodes bool, output StorageNodeSink) error {
 	if bytes.Equal(sr.Bytes(), emptyContractRoot.Bytes()) {
 		return nil
 	}
@@ -539,7 +540,7 @@ func (sdb *builder) buildStorageNodesEventual(sr common.Hash, watchedStorageKeys
 		return err
 	}
 	it := sTrie.NodeIterator(make([]byte, 0))
-	err = sdb.buildStorageNodesFromTrie(it, watchedStorageKeys, intermediateNodes, output)
+	err = sdb.buildStorageNodesFromTrie(it, intermediateNodes, output)
 	if err != nil {
 		return err
 	}
@@ -549,7 +550,7 @@ func (sdb *builder) buildStorageNodesEventual(sr common.Hash, watchedStorageKeys
 // buildStorageNodesFromTrie returns all the storage diff node objects in the provided node interator
 // if any storage keys are provided it will only return those leaf nodes
 // including intermediate nodes can be turned on or off
-func (sdb *builder) buildStorageNodesFromTrie(it trie.NodeIterator, watchedStorageKeys []common.Hash, intermediateNodes bool, output StorageNodeSink) error {
+func (sdb *builder) buildStorageNodesFromTrie(it trie.NodeIterator, intermediateNodes bool, output StorageNodeSink) error {
 	for it.Next(true) {
 		// skip value nodes
 		if it.Leaf() || bytes.Equal(nullHashBytes, it.Hash().Bytes()) {
@@ -565,7 +566,6 @@ func (sdb *builder) buildStorageNodesFromTrie(it trie.NodeIterator, watchedStora
 			valueNodePath := append(node.Path, partialPath...)
 			encodedPath := trie.HexToCompact(valueNodePath)
 			leafKey := encodedPath[1:]
-			if isWatchedStorageKey(watchedStorageKeys, leafKey) {
 			if err := output(StorageNode{
 				NodeType:  node.NodeType,
 				Path:      node.Path,
@@ -574,7 +574,6 @@ func (sdb *builder) buildStorageNodesFromTrie(it trie.NodeIterator, watchedStora
 			}); err != nil {
 				return err
 			}
-			}
 		case Extension, Branch:
 			if intermediateNodes {
 				if err := output(StorageNode{
@@ -593,7 +592,7 @@ func (sdb *builder) buildStorageNodesFromTrie(it trie.NodeIterator, watchedStora
 }
 
 // buildStorageNodesIncremental builds the storage diff node objects for all nodes that exist in a different state at B than A
-func (sdb *builder) buildStorageNodesIncremental(oldSR common.Hash, newSR common.Hash, watchedStorageKeys []common.Hash, intermediateNodes bool, output StorageNodeSink) error {
+func (sdb *builder) buildStorageNodesIncremental(oldSR common.Hash, newSR common.Hash, intermediateNodes bool, output StorageNodeSink) error {
 	if bytes.Equal(newSR.Bytes(), oldSR.Bytes()) {
 		return nil
 	}
@@ -609,19 +608,19 @@ func (sdb *builder) buildStorageNodesIncremental(oldSR common.Hash, newSR common
 
 	diffPathsAtB, err := sdb.createdAndUpdatedStorage(
 		oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}),
-		watchedStorageKeys, intermediateNodes, output)
+		intermediateNodes, output)
 	if err != nil {
 		return err
 	}
 	err = sdb.deletedOrUpdatedStorage(oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}),
-		diffPathsAtB, watchedStorageKeys, intermediateNodes, output)
+		diffPathsAtB, intermediateNodes, output)
 	if err != nil {
 		return err
 	}
 	return nil
 }
 
-func (sdb *builder) createdAndUpdatedStorage(a, b trie.NodeIterator, watchedKeys []common.Hash, intermediateNodes bool, output StorageNodeSink) (map[string]bool, error) {
+func (sdb *builder) createdAndUpdatedStorage(a, b trie.NodeIterator, intermediateNodes bool, output StorageNodeSink) (map[string]bool, error) {
 	diffPathsAtB := make(map[string]bool)
 	it, _ := trie.NewDifferenceIterator(a, b)
 	for it.Next(true) {
@@ -639,7 +638,6 @@ func (sdb *builder) createdAndUpdatedStorage(a, b trie.NodeIterator, watchedKeys
 			valueNodePath := append(node.Path, partialPath...)
 			encodedPath := trie.HexToCompact(valueNodePath)
 			leafKey := encodedPath[1:]
-			if isWatchedStorageKey(watchedKeys, leafKey) {
 			if err := output(StorageNode{
 				NodeType:  node.NodeType,
 				Path:      node.Path,
@@ -648,7 +646,6 @@ func (sdb *builder) createdAndUpdatedStorage(a, b trie.NodeIterator, watchedKeys
 			}); err != nil {
 				return nil, err
 			}
-			}
 		case Extension, Branch:
 			if intermediateNodes {
 				if err := output(StorageNode{
@@ -667,7 +664,7 @@ func (sdb *builder) createdAndUpdatedStorage(a, b trie.NodeIterator, watchedKeys
 	return diffPathsAtB, it.Error()
 }
 
-func (sdb *builder) deletedOrUpdatedStorage(a, b trie.NodeIterator, diffPathsAtB map[string]bool, watchedKeys []common.Hash, intermediateNodes bool, output StorageNodeSink) error {
+func (sdb *builder) deletedOrUpdatedStorage(a, b trie.NodeIterator, diffPathsAtB map[string]bool, intermediateNodes bool, output StorageNodeSink) error {
 	it, _ := trie.NewDifferenceIterator(b, a)
 	for it.Next(true) {
 		// skip value nodes
@@ -690,7 +687,6 @@ func (sdb *builder) deletedOrUpdatedStorage(a, b trie.NodeIterator, diffPathsAtB
 			valueNodePath := append(node.Path, partialPath...)
 			encodedPath := trie.HexToCompact(valueNodePath)
 			leafKey := encodedPath[1:]
-			if isWatchedStorageKey(watchedKeys, leafKey) {
 			if err := output(StorageNode{
 				NodeType:  Removed,
 				Path:      node.Path,
@@ -699,7 +695,6 @@ func (sdb *builder) deletedOrUpdatedStorage(a, b trie.NodeIterator, diffPathsAtB
 			}); err != nil {
 				return err
 			}
-			}
 		case Extension, Branch:
 			if intermediateNodes {
 				if err := output(StorageNode{
@@ -718,30 +713,12 @@ func (sdb *builder) deletedOrUpdatedStorage(a, b trie.NodeIterator, diffPathsAtB
 }
 
 // isWatchedAddress is used to check if a state account corresponds to one of the addresses the builder is configured to watch
-func isWatchedAddress(watchedAddresses []common.Address, stateLeafKey []byte) bool {
+func isWatchedAddress(watchedAddressesLeafKeys map[common.Hash]struct{}, stateLeafKey []byte) bool {
 	// If we aren't watching any specific addresses, we are watching everything
-	if len(watchedAddresses) == 0 {
+	if len(watchedAddressesLeafKeys) == 0 {
 		return true
 	}
-	for _, addr := range watchedAddresses {
-		addrHashKey := crypto.Keccak256(addr.Bytes())
-		if bytes.Equal(addrHashKey, stateLeafKey) {
-			return true
-		}
-	}
-	return false
-}
 
-// isWatchedStorageKey is used to check if a storage leaf corresponds to one of the storage slots the builder is configured to watch
+	_, ok := watchedAddressesLeafKeys[common.BytesToHash(stateLeafKey)]
-func isWatchedStorageKey(watchedKeys []common.Hash, storageLeafKey []byte) bool {
+	return ok
-	// If we aren't watching any specific addresses, we are watching everything
-	if len(watchedKeys) == 0 {
-		return true
-	}
-	for _, hashKey := range watchedKeys {
-		if bytes.Equal(hashKey.Bytes(), storageLeafKey) {
-			return true
-		}
-	}
-	return false
 }

statediff/builder_test.go

@@ -987,6 +987,7 @@ func TestBuilderWithWatchedAddressList(t *testing.T) {
 	params := statediff.Params{
 		WatchedAddresses: []common.Address{testhelpers.Account1Addr, testhelpers.ContractAddr},
 	}
+	params.ComputeWatchedAddressesLeafKeys()
 	builder = statediff.NewBuilder(chain.StateCache())
 
 	var tests = []struct {
@@ -1151,169 +1152,6 @@ func TestBuilderWithWatchedAddressList(t *testing.T) {
 	}
 }
 
-func TestBuilderWithWatchedAddressAndStorageKeyList(t *testing.T) {
-	blocks, chain := testhelpers.MakeChain(3, testhelpers.Genesis, testhelpers.TestChainGen)
-	contractLeafKey = testhelpers.AddressToLeafKey(testhelpers.ContractAddr)
-	defer chain.Stop()
-	block0 = testhelpers.Genesis
-	block1 = blocks[0]
-	block2 = blocks[1]
-	block3 = blocks[2]
-	params := statediff.Params{
-		WatchedAddresses:    []common.Address{testhelpers.Account1Addr, testhelpers.ContractAddr},
-		WatchedStorageSlots: []common.Hash{slot1StorageKey},
-	}
-	builder = statediff.NewBuilder(chain.StateCache())
-
-	var tests = []struct {
-		name              string
-		startingArguments statediff.Args
-		expected          *statediff.StateObject
-	}{
-		{
-			"testEmptyDiff",
-			statediff.Args{
-				OldStateRoot: block0.Root(),
-				NewStateRoot: block0.Root(),
-				BlockNumber:  block0.Number(),
-				BlockHash:    block0.Hash(),
-			},
-			&statediff.StateObject{
-				BlockNumber: block0.Number(),
-				BlockHash:   block0.Hash(),
-				Nodes:       emptyDiffs,
-			},
-		},
-		{
-			"testBlock0",
-			//10000 transferred from testBankAddress to account1Addr
-			statediff.Args{
-				OldStateRoot: testhelpers.NullHash,
-				NewStateRoot: block0.Root(),
-				BlockNumber:  block0.Number(),
-				BlockHash:    block0.Hash(),
-			},
-			&statediff.StateObject{
-				BlockNumber: block0.Number(),
-				BlockHash:   block0.Hash(),
-				Nodes:       emptyDiffs,
-			},
-		},
-		{
-			"testBlock1",
-			//10000 transferred from testBankAddress to account1Addr
-			statediff.Args{
-				OldStateRoot: block0.Root(),
-				NewStateRoot: block1.Root(),
-				BlockNumber:  block1.Number(),
-				BlockHash:    block1.Hash(),
-			},
-			&statediff.StateObject{
-				BlockNumber: block1.Number(),
-				BlockHash:   block1.Hash(),
-				Nodes: []sdtypes.StateNode{
-					{
-						Path:         []byte{'\x0e'},
-						NodeType:     sdtypes.Leaf,
-						LeafKey:      testhelpers.Account1LeafKey,
-						NodeValue:    account1AtBlock1LeafNode,
-						StorageNodes: emptyStorage,
-					},
-				},
-			},
-		},
-		{
-			"testBlock2",
-			//1000 transferred from testBankAddress to account1Addr
-			//1000 transferred from account1Addr to account2Addr
-			statediff.Args{
-				OldStateRoot: block1.Root(),
-				NewStateRoot: block2.Root(),
-				BlockNumber:  block2.Number(),
-				BlockHash:    block2.Hash(),
-			},
-			&statediff.StateObject{
-				BlockNumber: block2.Number(),
-				BlockHash:   block2.Hash(),
-				Nodes: []sdtypes.StateNode{
-					{
-						Path:      []byte{'\x06'},
-						NodeType:  sdtypes.Leaf,
-						LeafKey:   contractLeafKey,
-						NodeValue: contractAccountAtBlock2LeafNode,
-						StorageNodes: []sdtypes.StorageNode{
-							{
-								Path:      []byte{'\x0b'},
-								NodeType:  sdtypes.Leaf,
-								LeafKey:   slot1StorageKey.Bytes(),
-								NodeValue: slot1StorageLeafNode,
-							},
-						},
-					},
-					{
-						Path:         []byte{'\x0e'},
-						NodeType:     sdtypes.Leaf,
-						LeafKey:      testhelpers.Account1LeafKey,
-						NodeValue:    account1AtBlock2LeafNode,
-						StorageNodes: emptyStorage,
-					},
-				},
-				CodeAndCodeHashes: []sdtypes.CodeAndCodeHash{
-					{
-						Hash: testhelpers.CodeHash,
-						Code: testhelpers.ByteCodeAfterDeployment,
-					},
-				},
-			},
-		},
-		{
-			"testBlock3",
-			//the contract's storage is changed
-			//and the block is mined by account 2
-			statediff.Args{
-				OldStateRoot: block2.Root(),
-				NewStateRoot: block3.Root(),
-				BlockNumber:  block3.Number(),
-				BlockHash:    block3.Hash(),
-			},
-			&statediff.StateObject{
-				BlockNumber: block3.Number(),
-				BlockHash:   block3.Hash(),
-				Nodes: []sdtypes.StateNode{
-					{
-						Path:         []byte{'\x06'},
-						NodeType:     sdtypes.Leaf,
-						LeafKey:      contractLeafKey,
-						NodeValue:    contractAccountAtBlock3LeafNode,
-						StorageNodes: emptyStorage,
-					},
-				},
-			},
-		},
-	}
-
-	for _, test := range tests {
-		diff, err := builder.BuildStateDiffObject(test.startingArguments, params)
-		if err != nil {
-			t.Error(err)
-		}
-		receivedStateDiffRlp, err := rlp.EncodeToBytes(diff)
-		if err != nil {
-			t.Error(err)
-		}
-		expectedStateDiffRlp, err := rlp.EncodeToBytes(test.expected)
-		if err != nil {
-			t.Error(err)
-		}
-		sort.Slice(receivedStateDiffRlp, func(i, j int) bool { return receivedStateDiffRlp[i] < receivedStateDiffRlp[j] })
-		sort.Slice(expectedStateDiffRlp, func(i, j int) bool { return expectedStateDiffRlp[i] < expectedStateDiffRlp[j] })
-		if !bytes.Equal(receivedStateDiffRlp, expectedStateDiffRlp) {
-			t.Logf("Test failed: %s", test.name)
-			t.Errorf("actual state diff: %+v\nexpected state diff: %+v", diff, test.expected)
-		}
-	}
-}
-
 func TestBuilderWithRemovedAccountAndStorage(t *testing.T) {
 	blocks, chain := testhelpers.MakeChain(6, testhelpers.Genesis, testhelpers.TestChainGen)
 	contractLeafKey = testhelpers.AddressToLeafKey(testhelpers.ContractAddr)
@@ -1718,6 +1556,286 @@ func TestBuilderWithRemovedAccountAndStorageWithoutIntermediateNodes(t *testing.
 	}
 }
 
+func TestBuilderWithRemovedNonWatchedAccount(t *testing.T) {
+	blocks, chain := testhelpers.MakeChain(6, testhelpers.Genesis, testhelpers.TestChainGen)
+	contractLeafKey = testhelpers.AddressToLeafKey(testhelpers.ContractAddr)
+	defer chain.Stop()
+	block3 = blocks[2]
+	block4 = blocks[3]
+	block5 = blocks[4]
+	block6 = blocks[5]
+	params := statediff.Params{
+		WatchedAddresses: []common.Address{testhelpers.Account1Addr, testhelpers.Account2Addr},
+	}
+	params.ComputeWatchedAddressesLeafKeys()
+	builder = statediff.NewBuilder(chain.StateCache())
+
+	var tests = []struct {
+		name              string
+		startingArguments statediff.Args
+		expected          *statediff.StateObject
+	}{
+		{
+			"testBlock4",
+			statediff.Args{
+				OldStateRoot: block3.Root(),
+				NewStateRoot: block4.Root(),
+				BlockNumber:  block4.Number(),
+				BlockHash:    block4.Hash(),
+			},
+			&statediff.StateObject{
+				BlockNumber: block4.Number(),
+				BlockHash:   block4.Hash(),
+				Nodes: []sdtypes.StateNode{
+					{
+						Path:         []byte{'\x0c'},
+						NodeType:     sdtypes.Leaf,
+						LeafKey:      testhelpers.Account2LeafKey,
+						NodeValue:    account2AtBlock4LeafNode,
+						StorageNodes: emptyStorage,
+					},
+				},
+			},
+		},
+		{
+			"testBlock5",
+			statediff.Args{
+				OldStateRoot: block4.Root(),
+				NewStateRoot: block5.Root(),
+				BlockNumber:  block5.Number(),
+				BlockHash:    block5.Hash(),
+			},
+			&statediff.StateObject{
+				BlockNumber: block5.Number(),
+				BlockHash:   block5.Hash(),
+				Nodes: []sdtypes.StateNode{
+					{
+						Path:         []byte{'\x0e'},
+						NodeType:     sdtypes.Leaf,
+						LeafKey:      testhelpers.Account1LeafKey,
+						NodeValue:    account1AtBlock5LeafNode,
+						StorageNodes: emptyStorage,
+					},
+				},
+			},
+		},
+		{
+			"testBlock6",
+			statediff.Args{
+				OldStateRoot: block5.Root(),
+				NewStateRoot: block6.Root(),
+				BlockNumber:  block6.Number(),
+				BlockHash:    block6.Hash(),
+			},
+			&statediff.StateObject{
+				BlockNumber: block6.Number(),
+				BlockHash:   block6.Hash(),
+				Nodes: []sdtypes.StateNode{
+					{
+						Path:         []byte{'\x0c'},
+						NodeType:     sdtypes.Leaf,
+						LeafKey:      testhelpers.Account2LeafKey,
+						NodeValue:    account2AtBlock6LeafNode,
+						StorageNodes: emptyStorage,
+					},
+					{
+						Path:         []byte{'\x0e'},
+						NodeType:     sdtypes.Leaf,
+						LeafKey:      testhelpers.Account1LeafKey,
+						NodeValue:    account1AtBlock6LeafNode,
+						StorageNodes: emptyStorage,
+					},
+				},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		diff, err := builder.BuildStateDiffObject(test.startingArguments, params)
+		if err != nil {
+			t.Error(err)
+		}
+		receivedStateDiffRlp, err := rlp.EncodeToBytes(diff)
+		if err != nil {
+			t.Error(err)
+		}
+
+		expectedStateDiffRlp, err := rlp.EncodeToBytes(test.expected)
+		if err != nil {
+			t.Error(err)
+		}
+
+		sort.Slice(receivedStateDiffRlp, func(i, j int) bool { return receivedStateDiffRlp[i] < receivedStateDiffRlp[j] })
+		sort.Slice(expectedStateDiffRlp, func(i, j int) bool { return expectedStateDiffRlp[i] < expectedStateDiffRlp[j] })
+		if !bytes.Equal(receivedStateDiffRlp, expectedStateDiffRlp) {
+			t.Logf("Test failed: %s", test.name)
+			t.Errorf("actual state diff: %+v\r\n\r\n\r\nexpected state diff: %+v", diff, test.expected)
+		}
+	}
+}
+
+func TestBuilderWithRemovedWatchedAccount(t *testing.T) {
+	blocks, chain := testhelpers.MakeChain(6, testhelpers.Genesis, testhelpers.TestChainGen)
+	contractLeafKey = testhelpers.AddressToLeafKey(testhelpers.ContractAddr)
+	defer chain.Stop()
+	block3 = blocks[2]
+	block4 = blocks[3]
+	block5 = blocks[4]
+	block6 = blocks[5]
+	params := statediff.Params{
+		WatchedAddresses: []common.Address{testhelpers.Account1Addr, testhelpers.ContractAddr},
+	}
+	params.ComputeWatchedAddressesLeafKeys()
+	builder = statediff.NewBuilder(chain.StateCache())
+
+	var tests = []struct {
+		name              string
+		startingArguments statediff.Args
+		expected          *statediff.StateObject
+	}{
+		{
+			"testBlock4",
+			statediff.Args{
+				OldStateRoot: block3.Root(),
+				NewStateRoot: block4.Root(),
+				BlockNumber:  block4.Number(),
+				BlockHash:    block4.Hash(),
+			},
+			&statediff.StateObject{
+				BlockNumber: block4.Number(),
+				BlockHash:   block4.Hash(),
+				Nodes: []sdtypes.StateNode{
+					{
+						Path:      []byte{'\x06'},
+						NodeType:  sdtypes.Leaf,
+						LeafKey:   contractLeafKey,
+						NodeValue: contractAccountAtBlock4LeafNode,
+						StorageNodes: []sdtypes.StorageNode{
+							{
+								Path:      []byte{'\x04'},
+								NodeType:  sdtypes.Leaf,
+								LeafKey:   slot2StorageKey.Bytes(),
+								NodeValue: slot2StorageLeafNode,
+							},
+							{
+								Path:      []byte{'\x0b'},
+								NodeType:  sdtypes.Removed,
+								LeafKey:   slot1StorageKey.Bytes(),
+								NodeValue: []byte{},
+							},
+							{
+								Path:      []byte{'\x0c'},
+								NodeType:  sdtypes.Removed,
+								LeafKey:   slot3StorageKey.Bytes(),
+								NodeValue: []byte{},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			"testBlock5",
+			statediff.Args{
+				OldStateRoot: block4.Root(),
+				NewStateRoot: block5.Root(),
+				BlockNumber:  block5.Number(),
+				BlockHash:    block5.Hash(),
+			},
+			&statediff.StateObject{
+				BlockNumber: block5.Number(),
+				BlockHash:   block5.Hash(),
+				Nodes: []sdtypes.StateNode{
+					{
+						Path:      []byte{'\x06'},
+						NodeType:  sdtypes.Leaf,
+						LeafKey:   contractLeafKey,
+						NodeValue: contractAccountAtBlock5LeafNode,
+						StorageNodes: []sdtypes.StorageNode{
+							{
+								Path:      []byte{},
+								NodeType:  sdtypes.Leaf,
+								LeafKey:   slot0StorageKey.Bytes(),
+								NodeValue: slot0StorageLeafRootNode,
+							},
+							{
+								Path:      []byte{'\x02'},
+								NodeType:  sdtypes.Removed,
+								LeafKey:   slot0StorageKey.Bytes(),
+								NodeValue: []byte{},
+							},
+							{
+								Path:      []byte{'\x04'},
+								NodeType:  sdtypes.Removed,
+								LeafKey:   slot2StorageKey.Bytes(),
+								NodeValue: []byte{},
+							},
+						},
+					},
+					{
+						Path:         []byte{'\x0e'},
+						NodeType:     sdtypes.Leaf,
+						LeafKey:      testhelpers.Account1LeafKey,
+						NodeValue:    account1AtBlock5LeafNode,
+						StorageNodes: emptyStorage,
+					},
+				},
+			},
+		},
+		{
+			"testBlock6",
+			statediff.Args{
+				OldStateRoot: block5.Root(),
+				NewStateRoot: block6.Root(),
+				BlockNumber:  block6.Number(),
+				BlockHash:    block6.Hash(),
+			},
+			&statediff.StateObject{
+				BlockNumber: block6.Number(),
+				BlockHash:   block6.Hash(),
+				Nodes: []sdtypes.StateNode{
+					{
+						Path:      []byte{'\x06'},
+						NodeType:  sdtypes.Removed,
+						LeafKey:   contractLeafKey,
+						NodeValue: []byte{},
+					},
+					{
+						Path:         []byte{'\x0e'},
+						NodeType:     sdtypes.Leaf,
+						LeafKey:      testhelpers.Account1LeafKey,
+						NodeValue:    account1AtBlock6LeafNode,
+						StorageNodes: emptyStorage,
+					},
+				},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		diff, err := builder.BuildStateDiffObject(test.startingArguments, params)
+		if err != nil {
+			t.Error(err)
+		}
+		receivedStateDiffRlp, err := rlp.EncodeToBytes(diff)
+		if err != nil {
+			t.Error(err)
+		}
+
+		expectedStateDiffRlp, err := rlp.EncodeToBytes(test.expected)
+		if err != nil {
+			t.Error(err)
+		}
+
+		sort.Slice(receivedStateDiffRlp, func(i, j int) bool { return receivedStateDiffRlp[i] < receivedStateDiffRlp[j] })
+		sort.Slice(expectedStateDiffRlp, func(i, j int) bool { return expectedStateDiffRlp[i] < expectedStateDiffRlp[j] })
+		if !bytes.Equal(receivedStateDiffRlp, expectedStateDiffRlp) {
+			t.Logf("Test failed: %s", test.name)
+			t.Errorf("actual state diff: %+v\r\n\r\n\r\nexpected state diff: %+v", diff, test.expected)
+		}
+	}
+}
+
 var (
 	slot00StorageValue = common.Hex2Bytes("9471562b71999873db5b286df957af199ec94617f7") // prefixed TestBankAddress
 

statediff/helpers.go

@@ -20,8 +20,15 @@
 package statediff
 
 import (
+	"fmt"
 	"sort"
 	"strings"
+
+	"github.com/thoas/go-funk"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/statediff/indexer/postgres"
+	. "github.com/ethereum/go-ethereum/statediff/types"
 )
 
 func sortKeys(data AccountMap) []string {
@@ -69,5 +76,42 @@ func findIntersection(a, b []string) []string {
 			}
 		}
 	}
-
+}
+
+// loadWatchedAddresses is used to load watched addresses to in-memory write loop params from the db
+func loadWatchedAddresses(db *postgres.DB) error {
+	type Watched struct {
+		Address string `db:"address"`
+	}
+	var watched []Watched
+
+	pgStr := "SELECT address FROM eth_meta.watched_addresses"
+	err := db.Select(&watched, pgStr)
+	if err != nil {
+		return fmt.Errorf("error loading watched addresses: %v", err)
+	}
+
+	watchedAddresses := []common.Address{}
+	for _, entry := range watched {
+		watchedAddresses = append(watchedAddresses, common.HexToAddress(entry.Address))
+	}
+
+	writeLoopParams.Lock()
+	defer writeLoopParams.Unlock()
+	writeLoopParams.WatchedAddresses = watchedAddresses
+	writeLoopParams.ComputeWatchedAddressesLeafKeys()
+
+	return nil
+}
+
+// MapWatchAddressArgsToAddresses maps []WatchAddressArg to corresponding []common.Address
+func MapWatchAddressArgsToAddresses(args []WatchAddressArg) ([]common.Address, error) {
+	addresses, ok := funk.Map(args, func(arg WatchAddressArg) common.Address {
+		return common.HexToAddress(arg.Address)
+	}).([]common.Address)
+	if !ok {
+		return nil, fmt.Errorf(typeAssertionFailed)
+	}
+
+	return addresses, nil
 }

statediff/indexer/indexer.go

@@ -59,6 +59,12 @@ type Indexer interface {
 	PushStateNode(tx *BlockTx, stateNode sdtypes.StateNode) error
 	PushCodeAndCodeHash(tx *BlockTx, codeAndCodeHash sdtypes.CodeAndCodeHash) error
 	ReportDBMetrics(delay time.Duration, quit <-chan bool)
+
+	// Methods used by WatchAddress API/functionality.
+	InsertWatchedAddresses(addresses []sdtypes.WatchAddressArg, currentBlock *big.Int) error
+	RemoveWatchedAddresses(addresses []sdtypes.WatchAddressArg) error
+	SetWatchedAddresses(args []sdtypes.WatchAddressArg, currentBlockNumber *big.Int) error
+	ClearWatchedAddresses() error
 }
 
 // StateDiffIndexer satisfies the Indexer interface for ethereum statediff objects
@@ -549,3 +555,101 @@ func (sdi *StateDiffIndexer) PushCodeAndCodeHash(tx *BlockTx, codeAndCodeHash sd
 	}
 	return nil
 }
+
+// InsertWatchedAddresses inserts the given addresses in the database
+func (sdi *StateDiffIndexer) InsertWatchedAddresses(args []sdtypes.WatchAddressArg, currentBlockNumber *big.Int) error {
+	tx, err := sdi.dbWriter.db.Beginx()
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if p := recover(); p != nil {
+			shared.Rollback(tx)
+			panic(p)
+		} else if err != nil {
+			shared.Rollback(tx)
+		} else {
+			err = tx.Commit()
+		}
+	}()
+
+	for _, arg := range args {
+		_, err = tx.Exec(`INSERT INTO eth_meta.watched_addresses (address, created_at, watched_at) VALUES ($1, $2, $3) ON CONFLICT (address) DO NOTHING`,
+			arg.Address, arg.CreatedAt, currentBlockNumber.Uint64())
+		if err != nil {
+			return fmt.Errorf("error inserting watched_addresses entry: %v", err)
+		}
+	}
+
+	return err
+}
+
+// RemoveWatchedAddresses removes the given watched addresses from the database
+func (sdi *StateDiffIndexer) RemoveWatchedAddresses(args []sdtypes.WatchAddressArg) error {
+	tx, err := sdi.dbWriter.db.Beginx()
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if p := recover(); p != nil {
+			shared.Rollback(tx)
+			panic(p)
+		} else if err != nil {
+			shared.Rollback(tx)
+		} else {
+			err = tx.Commit()
+		}
+	}()
+
+	for _, arg := range args {
+		_, err = tx.Exec(`DELETE FROM eth_meta.watched_addresses WHERE address = $1`, arg.Address)
+		if err != nil {
+			return fmt.Errorf("error removing watched_addresses entry: %v", err)
+		}
+	}
+
+	return err
+}
+
+// SetWatchedAddresses clears and inserts the given addresses in the database
+func (sdi *StateDiffIndexer) SetWatchedAddresses(args []sdtypes.WatchAddressArg, currentBlockNumber *big.Int) error {
+	tx, err := sdi.dbWriter.db.Beginx()
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if p := recover(); p != nil {
+			shared.Rollback(tx)
+			panic(p)
+		} else if err != nil {
+			shared.Rollback(tx)
+		} else {
+			err = tx.Commit()
+		}
+	}()
+
+	_, err = tx.Exec(`DELETE FROM eth_meta.watched_addresses`)
+	if err != nil {
+		return fmt.Errorf("error setting watched_addresses table: %v", err)
+	}
+
+	for _, arg := range args {
+		_, err = tx.Exec(`INSERT INTO eth_meta.watched_addresses (address, created_at, watched_at) VALUES ($1, $2, $3) ON CONFLICT (address) DO NOTHING`,
+			arg.Address, arg.CreatedAt, currentBlockNumber.Uint64())
+		if err != nil {
+			return fmt.Errorf("error setting watched_addresses table: %v", err)
+		}
+	}
+
+	return err
+}
+
+// ClearWatchedAddresses clears all the watched addresses from the database
+func (sdi *StateDiffIndexer) ClearWatchedAddresses() error {
+	_, err := sdi.dbWriter.db.Exec(`DELETE FROM eth_meta.watched_addresses`)
+	if err != nil {
+		return fmt.Errorf("error clearing watched_addresses table: %v", err)
+	}
+
+	return nil
+}

statediff/indexer/indexer_test.go

@@ -19,6 +19,7 @@ package indexer_test
 import (
 	"bytes"
 	"fmt"
+	"math/big"
 	"os"
 	"testing"
 
@@ -32,6 +33,7 @@ import (
 	"github.com/ethereum/go-ethereum/statediff/indexer/models"
 	"github.com/ethereum/go-ethereum/statediff/indexer/postgres"
 	"github.com/ethereum/go-ethereum/statediff/indexer/shared"
+	sdtypes "github.com/ethereum/go-ethereum/statediff/types"
 	"github.com/ipfs/go-cid"
 	blockstore "github.com/ipfs/go-ipfs-blockstore"
 	dshelp "github.com/ipfs/go-ipfs-ds-help"
@@ -51,6 +53,9 @@ var (
 	rct1CID, rct2CID, rct3CID, rct4CID, rct5CID                                    cid.Cid
 	rctLeaf1, rctLeaf2, rctLeaf3, rctLeaf4, rctLeaf5                               []byte
 	state1CID, state2CID, storageCID                                               cid.Cid
+	contract1Address, contract2Address, contract3Address, contract4Address         string
+	contract1CreatedAt, contract2CreatedAt, contract3CreatedAt, contract4CreatedAt uint64
+	lastFilledAt, watchedAt1, watchedAt2, watchedAt3                               uint64
 )
 
 func expectTrue(t *testing.T, value bool) {
@@ -161,15 +166,33 @@ func init() {
 	rctLeaf3 = orderedRctLeafNodes[2]
 	rctLeaf4 = orderedRctLeafNodes[3]
 	rctLeaf5 = orderedRctLeafNodes[4]
+
+	contract1Address = "0x5d663F5269090bD2A7DC2390c911dF6083D7b28F"
+	contract2Address = "0x6Eb7e5C66DB8af2E96159AC440cbc8CDB7fbD26B"
+	contract3Address = "0xcfeB164C328CA13EFd3C77E1980d94975aDfedfc"
+	contract4Address = "0x0Edf0c4f393a628DE4828B228C48175b3EA297fc"
+	contract1CreatedAt = uint64(1)
+	contract2CreatedAt = uint64(2)
+	contract3CreatedAt = uint64(3)
+	contract4CreatedAt = uint64(4)
+
+	lastFilledAt = uint64(0)
+	watchedAt1 = uint64(10)
+	watchedAt2 = uint64(15)
+	watchedAt3 = uint64(20)
 }
 
-func setup(t *testing.T) {
+func setupIndexer(t *testing.T) {
 	db, err = shared.SetupDB()
 	if err != nil {
 		t.Fatal(err)
 	}
 	ind, err = indexer.NewStateDiffIndexer(mocks.TestConfig, db)
 	require.NoError(t, err)
+}
+
+func setup(t *testing.T) {
+	setupIndexer(t)
 	var tx *indexer.BlockTx
 	tx, err = ind.PushBlock(
 		mockBlock,
@@ -654,3 +677,297 @@ func TestPublishAndIndexer(t *testing.T) {
 		shared.ExpectEqual(t, data, []byte{})
 	})
 }
+
+func TestWatchAddressMethods(t *testing.T) {
+	setupIndexer(t)
+	defer tearDown(t)
+
+	type res struct {
+		Address      string `db:"address"`
+		CreatedAt    uint64 `db:"created_at"`
+		WatchedAt    uint64 `db:"watched_at"`
+		LastFilledAt uint64 `db:"last_filled_at"`
+	}
+	pgStr := "SELECT * FROM eth_meta.watched_addresses"
+
+	t.Run("Insert watched addresses", func(t *testing.T) {
+		args := []sdtypes.WatchAddressArg{
+			{
+				Address:   contract1Address,
+				CreatedAt: contract1CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		expectedData := []res{
+			{
+				Address:      contract1Address,
+				CreatedAt:    contract1CreatedAt,
+				WatchedAt:    watchedAt1,
+				LastFilledAt: lastFilledAt,
+			},
+			{
+				Address:      contract2Address,
+				CreatedAt:    contract2CreatedAt,
+				WatchedAt:    watchedAt1,
+				LastFilledAt: lastFilledAt,
+			},
+		}
+
+		ind.InsertWatchedAddresses(args, big.NewInt(int64(watchedAt1)))
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+
+	t.Run("Insert watched addresses (some already watched)", func(t *testing.T) {
+		args := []sdtypes.WatchAddressArg{
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		expectedData := []res{
+			{
+				Address:      contract1Address,
+				CreatedAt:    contract1CreatedAt,
+				WatchedAt:    watchedAt1,
+				LastFilledAt: lastFilledAt,
+			},
+			{
+				Address:      contract2Address,
+				CreatedAt:    contract2CreatedAt,
+				WatchedAt:    watchedAt1,
+				LastFilledAt: lastFilledAt,
+			},
+			{
+				Address:      contract3Address,
+				CreatedAt:    contract3CreatedAt,
+				WatchedAt:    watchedAt2,
+				LastFilledAt: lastFilledAt,
+			},
+		}
+
+		ind.InsertWatchedAddresses(args, big.NewInt(int64(watchedAt2)))
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+
+	t.Run("Remove watched addresses", func(t *testing.T) {
+		args := []sdtypes.WatchAddressArg{
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		expectedData := []res{
+			{
+				Address:      contract1Address,
+				CreatedAt:    contract1CreatedAt,
+				WatchedAt:    watchedAt1,
+				LastFilledAt: lastFilledAt,
+			},
+		}
+
+		ind.RemoveWatchedAddresses(args)
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+
+	t.Run("Remove watched addresses (some non-watched)", func(t *testing.T) {
+		args := []sdtypes.WatchAddressArg{
+			{
+				Address:   contract1Address,
+				CreatedAt: contract1CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		expectedData := []res{}
+
+		ind.RemoveWatchedAddresses(args)
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+
+	t.Run("Set watched addresses", func(t *testing.T) {
+		args := []sdtypes.WatchAddressArg{
+			{
+				Address:   contract1Address,
+				CreatedAt: contract1CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+		}
+		expectedData := []res{
+			{
+				Address:      contract1Address,
+				CreatedAt:    contract1CreatedAt,
+				WatchedAt:    watchedAt2,
+				LastFilledAt: lastFilledAt,
+			},
+			{
+				Address:      contract2Address,
+				CreatedAt:    contract2CreatedAt,
+				WatchedAt:    watchedAt2,
+				LastFilledAt: lastFilledAt,
+			},
+			{
+				Address:      contract3Address,
+				CreatedAt:    contract3CreatedAt,
+				WatchedAt:    watchedAt2,
+				LastFilledAt: lastFilledAt,
+			},
+		}
+
+		ind.SetWatchedAddresses(args, big.NewInt(int64(watchedAt2)))
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+
+	t.Run("Set watched addresses (some already watched)", func(t *testing.T) {
+		args := []sdtypes.WatchAddressArg{
+			{
+				Address:   contract4Address,
+				CreatedAt: contract4CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+		}
+		expectedData := []res{
+			{
+				Address:      contract4Address,
+				CreatedAt:    contract4CreatedAt,
+				WatchedAt:    watchedAt3,
+				LastFilledAt: lastFilledAt,
+			},
+			{
+				Address:      contract2Address,
+				CreatedAt:    contract2CreatedAt,
+				WatchedAt:    watchedAt3,
+				LastFilledAt: lastFilledAt,
+			},
+			{
+				Address:      contract3Address,
+				CreatedAt:    contract3CreatedAt,
+				WatchedAt:    watchedAt3,
+				LastFilledAt: lastFilledAt,
+			},
+		}
+
+		ind.SetWatchedAddresses(args, big.NewInt(int64(watchedAt3)))
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+
+	t.Run("Clear watched addresses", func(t *testing.T) {
+		expectedData := []res{}
+
+		ind.ClearWatchedAddresses()
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+
+	t.Run("Clear watched addresses (empty table)", func(t *testing.T) {
+		expectedData := []res{}
+
+		ind.ClearWatchedAddresses()
+
+		rows := []res{}
+		err = db.Select(&rows, pgStr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expectTrue(t, len(rows) == len(expectedData))
+		for idx, row := range rows {
+			shared.ExpectEqual(t, row, expectedData[idx])
+		}
+	})
+}

statediff/indexer/test_helpers.go

@@ -53,6 +53,10 @@ func TearDownDB(t *testing.T, db *postgres.DB) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	_, err = tx.Exec(`DELETE FROM eth_meta.watched_addresses`)
+	if err != nil {
+		t.Fatal(err)
+	}
 	err = tx.Commit()
 	if err != nil {
 		t.Fatal(err)

statediff/service.go

@@ -18,6 +18,7 @@ package statediff
 
 import (
 	"bytes"
+	"fmt"
 	"math/big"
 	"strconv"
 	"strings"
@@ -40,6 +41,7 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/ethereum/go-ethereum/trie"
+	"github.com/thoas/go-funk"
 
 	ind "github.com/ethereum/go-ethereum/statediff/indexer"
 	nodeinfo "github.com/ethereum/go-ethereum/statediff/indexer/node"
@@ -52,21 +54,26 @@ const (
 	genesisBlockNumber  = 0
 	defaultRetryLimit   = 3                   // default retry limit once deadlock is detected.
 	deadlockDetected    = "deadlock detected" // 40P01 https://www.postgresql.org/docs/current/errcodes-appendix.html
+	typeAssertionFailed = "type assertion failed"
+	unexpectedOperation = "unexpected operation"
 )
 
-var writeLoopParams = Params{
+var writeLoopParams = ParamsWithMutex{
+	Params: Params{
 		IntermediateStateNodes:   true,
 		IntermediateStorageNodes: true,
 		IncludeBlock:             true,
 		IncludeReceipts:          true,
 		IncludeTD:                true,
 		IncludeCode:              true,
+	},
 }
 
 var statediffMetrics = RegisterStatediffMetrics(metrics.DefaultRegistry)
 
 type blockChain interface {
 	SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription
+	CurrentBlock() *types.Block
 	GetBlockByHash(hash common.Hash) *types.Block
 	GetBlockByNumber(number uint64) *types.Block
 	GetReceiptsByHash(hash common.Hash) types.Receipts
@@ -101,6 +108,8 @@ type IService interface {
 	WriteStateDiffFor(blockHash common.Hash, params Params) error
 	// Event loop for progressively processing and writing diffs directly to DB
 	WriteLoop(chainEventCh chan core.ChainEvent)
+	// Method to change the addresses being watched in write loop params
+	WatchAddress(operation OperationType, args []WatchAddressArg) error
 }
 
 // Wraps consructor parameters
@@ -159,6 +168,8 @@ func NewBlockCache(max uint) blockCache {
 func New(stack *node.Node, ethServ *eth.Ethereum, cfg *ethconfig.Config, params ServiceParams) error {
 	blockChain := ethServ.BlockChain()
 	var indexer ind.Indexer
+	var db *postgres.DB
+	var err error
 	quitCh := make(chan bool)
 	if params.DBParams != nil {
 		info := nodeinfo.Info{
@@ -170,7 +181,7 @@ func New(stack *node.Node, ethServ *eth.Ethereum, cfg *ethconfig.Config, params
 		}
 
 		// TODO: pass max idle, open, lifetime?
-		db, err := postgres.NewDB(params.DBParams.ConnectionURL, postgres.ConnectionConfig{}, info)
+		db, err = postgres.NewDB(params.DBParams.ConnectionURL, postgres.ConnectionConfig{}, info)
 		if err != nil {
 			return err
 		}
@@ -200,6 +211,12 @@ func New(stack *node.Node, ethServ *eth.Ethereum, cfg *ethconfig.Config, params
 	}
 	stack.RegisterLifecycle(sds)
 	stack.RegisterAPIs(sds.APIs())
+
+	err = loadWatchedAddresses(db)
+	if err != nil {
+		return err
+	}
+
 	return nil
 }
 
@@ -278,7 +295,9 @@ func (sds *Service) WriteLoop(chainEventCh chan core.ChainEvent) {
 func (sds *Service) writeGenesisStateDiff(currBlock *types.Block, workerId uint) {
 	// For genesis block we need to return the entire state trie hence we diff it with an empty trie.
 	log.Info("Writing state diff", "block height", genesisBlockNumber, "worker", workerId)
-	err := sds.writeStateDiffWithRetry(currBlock, common.Hash{}, writeLoopParams)
+	writeLoopParams.RLock()
+	err := sds.writeStateDiffWithRetry(currBlock, common.Hash{}, writeLoopParams.Params)
+	writeLoopParams.RUnlock()
 	if err != nil {
 		log.Error("statediff.Service.WriteLoop: processing error", "block height",
 			genesisBlockNumber, "error", err.Error(), "worker", workerId)
@@ -307,7 +326,9 @@ func (sds *Service) writeLoopWorker(params workerParams) {
 			}
 
 			log.Info("Writing state diff", "block height", currentBlock.Number().Uint64(), "worker", params.id)
-			err := sds.writeStateDiffWithRetry(currentBlock, parentBlock.Root(), writeLoopParams)
+			writeLoopParams.RLock()
+			err := sds.writeStateDiffWithRetry(currentBlock, parentBlock.Root(), writeLoopParams.Params)
+			writeLoopParams.RUnlock()
 			if err != nil {
 				log.Error("statediff.Service.WriteLoop: processing error", "block height", currentBlock.Number().Uint64(), "error", err.Error(), "worker", params.id)
 				continue
@@ -402,6 +423,9 @@ func (sds *Service) streamStateDiff(currentBlock *types.Block, parentRoot common
 func (sds *Service) StateDiffAt(blockNumber uint64, params Params) (*Payload, error) {
 	currentBlock := sds.BlockChain.GetBlockByNumber(blockNumber)
 	log.Info("sending state diff", "block height", blockNumber)
+
+	params.ComputeWatchedAddressesLeafKeys()
+
 	if blockNumber == 0 {
 		return sds.processStateDiff(currentBlock, common.Hash{}, params)
 	}
@@ -414,6 +438,9 @@ func (sds *Service) StateDiffAt(blockNumber uint64, params Params) (*Payload, er
 func (sds *Service) StateDiffFor(blockHash common.Hash, params Params) (*Payload, error) {
 	currentBlock := sds.BlockChain.GetBlockByHash(blockHash)
 	log.Info("sending state diff", "block hash", blockHash)
+
+	params.ComputeWatchedAddressesLeafKeys()
+
 	if currentBlock.NumberU64() == 0 {
 		return sds.processStateDiff(currentBlock, common.Hash{}, params)
 	}
@@ -472,6 +499,9 @@ func (sds *Service) newPayload(stateObject []byte, block *types.Block, params Pa
 func (sds *Service) StateTrieAt(blockNumber uint64, params Params) (*Payload, error) {
 	currentBlock := sds.BlockChain.GetBlockByNumber(blockNumber)
 	log.Info("sending state trie", "block height", blockNumber)
+
+	params.ComputeWatchedAddressesLeafKeys()
+
 	return sds.processStateTrie(currentBlock, params)
 }
 
@@ -494,6 +524,9 @@ func (sds *Service) Subscribe(id rpc.ID, sub chan<- Payload, quitChan chan<- boo
 	if atomic.CompareAndSwapInt32(&sds.subscribers, 0, 1) {
 		log.Info("State diffing subscription received; beginning statediff processing")
 	}
+
+	params.ComputeWatchedAddressesLeafKeys()
+
 	// Subscription type is defined as the hash of the rlp-serialized subscription params
 	by, err := rlp.EncodeToBytes(params)
 	if err != nil {
@@ -543,7 +576,7 @@ func (sds *Service) Start() error {
 	go sds.Loop(chainEventCh)
 
 	if sds.enableWriteLoop {
-		log.Info("Starting statediff DB write loop", "params", writeLoopParams)
+		log.Info("Starting statediff DB write loop", "params", writeLoopParams.Params)
 		chainEventCh := make(chan core.ChainEvent, chainEventChanSize)
 		go sds.WriteLoop(chainEventCh)
 	}
@@ -640,6 +673,8 @@ func (sds *Service) StreamCodeAndCodeHash(blockNumber uint64, outChan chan<- Cod
 // This operation cannot be performed back past the point of db pruning; it requires an archival node
 // for historical data
 func (sds *Service) WriteStateDiffAt(blockNumber uint64, params Params) error {
+	params.ComputeWatchedAddressesLeafKeys()
+
 	currentBlock := sds.BlockChain.GetBlockByNumber(blockNumber)
 	parentRoot := common.Hash{}
 	if blockNumber != 0 {
@@ -653,6 +688,8 @@ func (sds *Service) WriteStateDiffAt(blockNumber uint64, params Params) error {
 // This operation cannot be performed back past the point of db pruning; it requires an archival node
 // for historical data
 func (sds *Service) WriteStateDiffFor(blockHash common.Hash, params Params) error {
+	params.ComputeWatchedAddressesLeafKeys()
+
 	currentBlock := sds.BlockChain.GetBlockByHash(blockHash)
 	parentRoot := common.Hash{}
 	if currentBlock.NumberU64() != 0 {
@@ -713,3 +750,102 @@ func (sds *Service) writeStateDiffWithRetry(block *types.Block, parentRoot commo
 	}
 	return err
 }
+
+// Performs one of following operations on the watched addresses in writeLoopParams and the db:
+// add | remove | set | clear
+func (sds *Service) WatchAddress(operation OperationType, args []WatchAddressArg) error {
+	// lock writeLoopParams for a write
+	writeLoopParams.Lock()
+	defer writeLoopParams.Unlock()
+
+	// get the current block number
+	currentBlockNumber := sds.BlockChain.CurrentBlock().Number()
+
+	switch operation {
+	case Add:
+		// filter out args having an already watched address with a warning
+		filteredArgs, ok := funk.Filter(args, func(arg WatchAddressArg) bool {
+			if funk.Contains(writeLoopParams.WatchedAddresses, common.HexToAddress(arg.Address)) {
+				log.Warn("Address already being watched", "address", arg.Address)
+				return false
+			}
+			return true
+		}).([]WatchAddressArg)
+		if !ok {
+			return fmt.Errorf("add: filtered args %s", typeAssertionFailed)
+		}
+
+		// get addresses from the filtered args
+		filteredAddresses, err := MapWatchAddressArgsToAddresses(filteredArgs)
+		if err != nil {
+			return fmt.Errorf("add: filtered addresses %s", err.Error())
+		}
+
+		// update the db
+		err = sds.indexer.InsertWatchedAddresses(filteredArgs, currentBlockNumber)
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		writeLoopParams.WatchedAddresses = append(writeLoopParams.WatchedAddresses, filteredAddresses...)
+		funk.ForEach(filteredAddresses, func(address common.Address) {
+			writeLoopParams.watchedAddressesLeafKeys[crypto.Keccak256Hash(address.Bytes())] = struct{}{}
+		})
+	case Remove:
+		// get addresses from args
+		argAddresses, err := MapWatchAddressArgsToAddresses(args)
+		if err != nil {
+			return fmt.Errorf("remove: mapped addresses %s", err.Error())
+		}
+
+		// remove the provided addresses from currently watched addresses
+		addresses, ok := funk.Subtract(writeLoopParams.WatchedAddresses, argAddresses).([]common.Address)
+		if !ok {
+			return fmt.Errorf("remove: filtered addresses %s", typeAssertionFailed)
+		}
+
+		// update the db
+		err = sds.indexer.RemoveWatchedAddresses(args)
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		writeLoopParams.WatchedAddresses = addresses
+		funk.ForEach(argAddresses, func(address common.Address) {
+			delete(writeLoopParams.watchedAddressesLeafKeys, crypto.Keccak256Hash(address.Bytes()))
+		})
+	case Set:
+		// get addresses from args
+		argAddresses, err := MapWatchAddressArgsToAddresses(args)
+		if err != nil {
+			return fmt.Errorf("set: mapped addresses %s", err.Error())
+		}
+
+		// update the db
+		err = sds.indexer.SetWatchedAddresses(args, currentBlockNumber)
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		writeLoopParams.WatchedAddresses = argAddresses
+		writeLoopParams.ComputeWatchedAddressesLeafKeys()
+	case Clear:
+		// update the db
+		err := sds.indexer.ClearWatchedAddresses()
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		writeLoopParams.WatchedAddresses = []common.Address{}
+		writeLoopParams.ComputeWatchedAddressesLeafKeys()
+
+	default:
+		return fmt.Errorf("%s %s", unexpectedOperation, operation)
+	}
+
+	return nil
+}

statediff/service_test.go

@@ -144,6 +144,7 @@ func testErrorInChainEventLoop(t *testing.T) {
 		}
 	}
 
+	defaultParams.ComputeWatchedAddressesLeafKeys()
 	if !reflect.DeepEqual(builder.Params, defaultParams) {
 		t.Error("Test failure:", t.Name())
 		t.Logf("Actual params does not equal expected.\nactual:%+v\nexpected: %+v", builder.Params, defaultParams)
@@ -195,6 +196,8 @@ func testErrorInBlockLoop(t *testing.T) {
 		}
 	}()
 	service.Loop(eventsChannel)
+
+	defaultParams.ComputeWatchedAddressesLeafKeys()
 	if !reflect.DeepEqual(builder.Params, defaultParams) {
 		t.Error("Test failure:", t.Name())
 		t.Logf("Actual params does not equal expected.\nactual:%+v\nexpected: %+v", builder.Params, defaultParams)
@@ -268,6 +271,8 @@ func testErrorInStateDiffAt(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
+
+	defaultParams.ComputeWatchedAddressesLeafKeys()
 	if !reflect.DeepEqual(builder.Params, defaultParams) {
 		t.Error("Test failure:", t.Name())
 		t.Logf("Actual params does not equal expected.\nactual:%+v\nexpected: %+v", builder.Params, defaultParams)

statediff/testhelpers/mocks/blockchain.go

@@ -39,6 +39,7 @@ type BlockChain struct {
 	Receipts               map[common.Hash]types.Receipts
 	TDByHash               map[common.Hash]*big.Int
 	TDByNum                map[uint64]*big.Int
+	currentBlock           *types.Block
 }
 
 // SetBlocksForHashes mock method
@@ -128,6 +129,16 @@ func (bc *BlockChain) GetTd(hash common.Hash, blockNum uint64) *big.Int {
 	return nil
 }
 
+// SetCurrentBlock test method
+func (bc *BlockChain) SetCurrentBlock(block *types.Block) {
+	bc.currentBlock = block
+}
+
+// CurrentBlock mock method
+func (bc *BlockChain) CurrentBlock() *types.Block {
+	return bc.currentBlock
+}
+
 func (bc *BlockChain) SetTd(hash common.Hash, blockNum uint64, td *big.Int) {
 	if bc.TDByHash == nil {
 		bc.TDByHash = make(map[common.Hash]*big.Int)

statediff/testhelpers/mocks/indexer.go

@@ -0,0 +1,59 @@
+// Copyright 2022 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package mocks
+
+import (
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/statediff/indexer"
+	sdtypes "github.com/ethereum/go-ethereum/statediff/types"
+)
+
+// Indexer is a mock state diff indexer
+type Indexer struct{}
+
+func (sdi *Indexer) PushBlock(block *types.Block, receipts types.Receipts, totalDifficulty *big.Int) (*indexer.BlockTx, error) {
+	return nil, nil
+}
+
+func (sdi *Indexer) PushStateNode(tx *indexer.BlockTx, stateNode sdtypes.StateNode) error {
+	return nil
+}
+
+func (sdi *Indexer) PushCodeAndCodeHash(tx *indexer.BlockTx, codeAndCodeHash sdtypes.CodeAndCodeHash) error {
+	return nil
+}
+
+func (sdi *Indexer) ReportDBMetrics(delay time.Duration, quit <-chan bool) {}
+
+func (sdi *Indexer) InsertWatchedAddresses(addresses []sdtypes.WatchAddressArg, currentBlock *big.Int) error {
+	return nil
+}
+
+func (sdi *Indexer) RemoveWatchedAddresses(addresses []sdtypes.WatchAddressArg) error {
+	return nil
+}
+
+func (sdi *Indexer) SetWatchedAddresses(args []sdtypes.WatchAddressArg, currentBlockNumber *big.Int) error {
+	return nil
+}
+
+func (sdi *Indexer) ClearWatchedAddresses() error {
+	return nil
+}

statediff/testhelpers/mocks/service.go

@@ -25,6 +25,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/thoas/go-funk"
 
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -32,9 +33,15 @@ import (
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/ethereum/go-ethereum/statediff"
+	ind "github.com/ethereum/go-ethereum/statediff/indexer"
 	sdtypes "github.com/ethereum/go-ethereum/statediff/types"
 )
 
+var (
+	typeAssertionFailed = "type assertion failed"
+	unexpectedOperation = "unexpected operation"
+)
+
 // MockStateDiffService is a mock state diff service
 type MockStateDiffService struct {
 	sync.Mutex
@@ -47,6 +54,8 @@ type MockStateDiffService struct {
 	QuitChan          chan bool
 	Subscriptions     map[common.Hash]map[rpc.ID]statediff.Subscription
 	SubscriptionTypes map[common.Hash]statediff.Params
+	Indexer           ind.Indexer
+	writeLoopParams   statediff.ParamsWithMutex
 }
 
 // Protocols mock method
@@ -332,3 +341,97 @@ func sendNonBlockingQuit(id rpc.ID, sub statediff.Subscription) {
 		log.Info("unable to close subscription %s; channel has no receiver", id)
 	}
 }
+
+// WatchAddress mock method
+func (sds *MockStateDiffService) WatchAddress(operation statediff.OperationType, args []sdtypes.WatchAddressArg) error {
+	// lock writeLoopParams for a write
+	sds.writeLoopParams.Lock()
+	defer sds.writeLoopParams.Unlock()
+
+	// get the current block number
+	currentBlockNumber := sds.BlockChain.CurrentBlock().Number()
+
+	switch operation {
+	case statediff.Add:
+		// filter out args having an already watched address with a warning
+		filteredArgs, ok := funk.Filter(args, func(arg sdtypes.WatchAddressArg) bool {
+			if funk.Contains(sds.writeLoopParams.WatchedAddresses, common.HexToAddress(arg.Address)) {
+				log.Warn("Address already being watched", "address", arg.Address)
+				return false
+			}
+			return true
+		}).([]sdtypes.WatchAddressArg)
+		if !ok {
+			return fmt.Errorf("add: filtered args %s", typeAssertionFailed)
+		}
+
+		// get addresses from the filtered args
+		filteredAddresses, err := statediff.MapWatchAddressArgsToAddresses(filteredArgs)
+		if err != nil {
+			return fmt.Errorf("add: filtered addresses %s", err.Error())
+		}
+
+		// update the db
+		err = sds.Indexer.InsertWatchedAddresses(filteredArgs, currentBlockNumber)
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		sds.writeLoopParams.WatchedAddresses = append(sds.writeLoopParams.WatchedAddresses, filteredAddresses...)
+		sds.writeLoopParams.ComputeWatchedAddressesLeafKeys()
+	case statediff.Remove:
+		// get addresses from args
+		argAddresses, err := statediff.MapWatchAddressArgsToAddresses(args)
+		if err != nil {
+			return fmt.Errorf("remove: mapped addresses %s", err.Error())
+		}
+
+		// remove the provided addresses from currently watched addresses
+		addresses, ok := funk.Subtract(sds.writeLoopParams.WatchedAddresses, argAddresses).([]common.Address)
+		if !ok {
+			return fmt.Errorf("remove: filtered addresses %s", typeAssertionFailed)
+		}
+
+		// update the db
+		err = sds.Indexer.RemoveWatchedAddresses(args)
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		sds.writeLoopParams.WatchedAddresses = addresses
+		sds.writeLoopParams.ComputeWatchedAddressesLeafKeys()
+	case statediff.Set:
+		// get addresses from args
+		argAddresses, err := statediff.MapWatchAddressArgsToAddresses(args)
+		if err != nil {
+			return fmt.Errorf("set: mapped addresses %s", err.Error())
+		}
+
+		// update the db
+		err = sds.Indexer.SetWatchedAddresses(args, currentBlockNumber)
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		sds.writeLoopParams.WatchedAddresses = argAddresses
+		sds.writeLoopParams.ComputeWatchedAddressesLeafKeys()
+	case statediff.Clear:
+		// update the db
+		err := sds.Indexer.ClearWatchedAddresses()
+		if err != nil {
+			return err
+		}
+
+		// update in-memory params
+		sds.writeLoopParams.WatchedAddresses = []common.Address{}
+		sds.writeLoopParams.ComputeWatchedAddressesLeafKeys()
+
+	default:
+		return fmt.Errorf("%s %s", unexpectedOperation, operation)
+	}
+
+	return nil
+}

statediff/testhelpers/mocks/service_test.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"math/big"
 	"os"
+	"reflect"
 	"sort"
 	"sync"
 	"testing"
@@ -87,6 +88,7 @@ func init() {
 func TestAPI(t *testing.T) {
 	testSubscriptionAPI(t)
 	testHTTPAPI(t)
+	testWatchAddressAPI(t)
 }
 
 func testSubscriptionAPI(t *testing.T) {
@@ -246,3 +248,286 @@ func testHTTPAPI(t *testing.T) {
 		t.Errorf("paylaod does not have the expected total difficulty\r\nactual td: %d\r\nexpected td: %d", payload.TotalDifficulty.Int64(), mockTotalDifficulty.Int64())
 	}
 }
+
+func testWatchAddressAPI(t *testing.T) {
+	blocks, chain := testhelpers.MakeChain(6, testhelpers.Genesis, testhelpers.TestChainGen)
+	defer chain.Stop()
+	block6 := blocks[5]
+
+	mockBlockChain := &BlockChain{}
+	mockBlockChain.SetCurrentBlock(block6)
+	mockIndexer := Indexer{}
+	mockService := MockStateDiffService{
+		BlockChain: mockBlockChain,
+		Indexer:    &mockIndexer,
+	}
+
+	// test data
+	var (
+		contract1Address   = "0x5d663F5269090bD2A7DC2390c911dF6083D7b28F"
+		contract2Address   = "0x6Eb7e5C66DB8af2E96159AC440cbc8CDB7fbD26B"
+		contract3Address   = "0xcfeB164C328CA13EFd3C77E1980d94975aDfedfc"
+		contract4Address   = "0x0Edf0c4f393a628DE4828B228C48175b3EA297fc"
+		contract1CreatedAt = uint64(1)
+		contract2CreatedAt = uint64(2)
+		contract3CreatedAt = uint64(3)
+		contract4CreatedAt = uint64(4)
+
+		args1 = []sdtypes.WatchAddressArg{
+			{
+				Address:   contract1Address,
+				CreatedAt: contract1CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		startingParams1 = statediff.Params{
+			WatchedAddresses: []common.Address{},
+		}
+		expectedParams1 = statediff.Params{
+			WatchedAddresses: []common.Address{
+				common.HexToAddress(contract1Address),
+				common.HexToAddress(contract2Address),
+			},
+		}
+
+		args2 = []sdtypes.WatchAddressArg{
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		startingParams2 = expectedParams1
+		expectedParams2 = statediff.Params{
+			WatchedAddresses: []common.Address{
+				common.HexToAddress(contract1Address),
+				common.HexToAddress(contract2Address),
+				common.HexToAddress(contract3Address),
+			},
+		}
+
+		args3 = []sdtypes.WatchAddressArg{
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		startingParams3 = expectedParams2
+		expectedParams3 = statediff.Params{
+			WatchedAddresses: []common.Address{
+				common.HexToAddress(contract1Address),
+			},
+		}
+
+		args4 = []sdtypes.WatchAddressArg{
+			{
+				Address:   contract1Address,
+				CreatedAt: contract1CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+		}
+		startingParams4 = expectedParams3
+		expectedParams4 = statediff.Params{
+			WatchedAddresses: []common.Address{},
+		}
+
+		args5 = []sdtypes.WatchAddressArg{
+			{
+				Address:   contract1Address,
+				CreatedAt: contract1CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+		}
+		startingParams5 = expectedParams4
+		expectedParams5 = statediff.Params{
+			WatchedAddresses: []common.Address{
+				common.HexToAddress(contract1Address),
+				common.HexToAddress(contract2Address),
+				common.HexToAddress(contract3Address),
+			},
+		}
+
+		args6 = []sdtypes.WatchAddressArg{
+			{
+				Address:   contract4Address,
+				CreatedAt: contract4CreatedAt,
+			},
+			{
+				Address:   contract2Address,
+				CreatedAt: contract2CreatedAt,
+			},
+			{
+				Address:   contract3Address,
+				CreatedAt: contract3CreatedAt,
+			},
+		}
+		startingParams6 = expectedParams5
+		expectedParams6 = statediff.Params{
+			WatchedAddresses: []common.Address{
+				common.HexToAddress(contract4Address),
+				common.HexToAddress(contract2Address),
+				common.HexToAddress(contract3Address),
+			},
+		}
+
+		args7           = []sdtypes.WatchAddressArg{}
+		startingParams7 = expectedParams6
+		expectedParams7 = statediff.Params{
+			WatchedAddresses: []common.Address{},
+		}
+
+		args8           = []sdtypes.WatchAddressArg{}
+		startingParams8 = expectedParams6
+		expectedParams8 = statediff.Params{
+			WatchedAddresses: []common.Address{},
+		}
+
+		args9           = []sdtypes.WatchAddressArg{}
+		startingParams9 = expectedParams8
+		expectedParams9 = statediff.Params{
+			WatchedAddresses: []common.Address{},
+		}
+	)
+
+	tests := []struct {
+		name           string
+		operation      statediff.OperationType
+		args           []sdtypes.WatchAddressArg
+		startingParams statediff.Params
+		expectedParams statediff.Params
+		expectedErr    error
+	}{
+		{
+			"testAddAddresses",
+			statediff.Add,
+			args1,
+			startingParams1,
+			expectedParams1,
+			nil,
+		},
+		{
+			"testAddAddressesSomeWatched",
+			statediff.Add,
+			args2,
+			startingParams2,
+			expectedParams2,
+			nil,
+		},
+		{
+			"testRemoveAddresses",
+			statediff.Remove,
+			args3,
+			startingParams3,
+			expectedParams3,
+			nil,
+		},
+		{
+			"testRemoveAddressesSomeWatched",
+			statediff.Remove,
+			args4,
+			startingParams4,
+			expectedParams4,
+			nil,
+		},
+		{
+			"testSetAddresses",
+			statediff.Set,
+			args5,
+			startingParams5,
+			expectedParams5,
+			nil,
+		},
+		{
+			"testSetAddressesSomeWatched",
+			statediff.Set,
+			args6,
+			startingParams6,
+			expectedParams6,
+			nil,
+		},
+		{
+			"testSetAddressesEmtpyArgs",
+			statediff.Set,
+			args7,
+			startingParams7,
+			expectedParams7,
+			nil,
+		},
+		{
+			"testClearAddresses",
+			statediff.Clear,
+			args8,
+			startingParams8,
+			expectedParams8,
+			nil,
+		},
+		{
+			"testClearAddressesEmpty",
+			statediff.Clear,
+			args9,
+			startingParams9,
+			expectedParams9,
+			nil,
+		},
+
+		// invalid args
+		{
+			"testInvalidOperation",
+			"WrongOp",
+			args9,
+			startingParams9,
+			statediff.Params{},
+			fmt.Errorf("%s WrongOp", unexpectedOperation),
+		},
+	}
+
+	for _, test := range tests {
+		// set indexing params
+		mockService.writeLoopParams = statediff.ParamsWithMutex{
+			Params: test.startingParams,
+		}
+		mockService.writeLoopParams.ComputeWatchedAddressesLeafKeys()
+
+		// make the API call to change watched addresses
+		err := mockService.WatchAddress(test.operation, test.args)
+		if test.expectedErr != nil {
+			if err.Error() != test.expectedErr.Error() {
+				t.Logf("Test failed: %s", test.name)
+				t.Errorf("actual err: %+v\nexpected err: %+v", err, test.expectedErr)
+			}
+
+			continue
+		}
+		if err != nil {
+			t.Error(err)
+		}
+
+		// check updated indexing params
+		test.expectedParams.ComputeWatchedAddressesLeafKeys()
+		updatedParams := mockService.writeLoopParams.Params
+		if !reflect.DeepEqual(updatedParams, test.expectedParams) {
+			t.Logf("Test failed: %s", test.name)
+			t.Errorf("actual params: %+v\nexpected params: %+v", updatedParams, test.expectedParams)
+		}
+	}
+}

statediff/types.go

@@ -22,9 +22,11 @@ package statediff
 import (
 	"encoding/json"
 	"math/big"
+	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
 	ctypes "github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/statediff/types"
 )
 
@@ -50,7 +52,21 @@ type Params struct {
 	IncludeTD                bool
 	IncludeCode              bool
 	WatchedAddresses         []common.Address
-	WatchedStorageSlots      []common.Hash
+	watchedAddressesLeafKeys map[common.Hash]struct{}
+}
+
+// ComputeWatchedAddressesLeafKeys populates a map with keys (Keccak256Hash) of each of the WatchedAddresses
+func (p *Params) ComputeWatchedAddressesLeafKeys() {
+	p.watchedAddressesLeafKeys = make(map[common.Hash]struct{}, len(p.WatchedAddresses))
+	for _, address := range p.WatchedAddresses {
+		p.watchedAddressesLeafKeys[crypto.Keccak256Hash(address.Bytes())] = struct{}{}
+	}
+}
+
+// ParamsWithMutex allows to lock the parameters while they are being updated | read from
+type ParamsWithMutex struct {
+	Params
+	sync.RWMutex
 }
 
 // Args bundles the arguments for the state diff builder
@@ -111,3 +127,13 @@ type accountWrapper struct {
 	NodeValue []byte
 	LeafKey   []byte
 }
+
+// OperationType for type of WatchAddress operation
+type OperationType string
+
+const (
+	Add    OperationType = "add"
+	Remove OperationType = "remove"
+	Set    OperationType = "set"
+	Clear  OperationType = "clear"
+)

statediff/types/types.go

@@ -74,3 +74,10 @@ type CodeAndCodeHash struct {
 type StateNodeSink func(StateNode) error
 type StorageNodeSink func(StorageNode) error
 type CodeSink func(CodeAndCodeHash) error
+
+// WatchAddressArg is a arg type for WatchAddress API
+type WatchAddressArg struct {
+	// Address represents common.Address
+	Address   string
+	CreatedAt uint64
+}