eth_newBlockFilter and related functionality (#232)

* add filter types for block, pending tx, log
* implement pollForBlocks for block filters
* implement getFilterChanges for block filter
* implement uninstall filter by stopping polling

CHANGELOG.md

@@ -50,3 +50,11 @@ Ref: https://keepachangelog.com/en/1.0.0/
   * (app/ante) Moved `AnteHandler` implementation to `app/ante`
   * (keys) Marked `ExportEthKeyCommand` as **UNSAFE**
   * (x/evm) Moved `BeginBlock` and `EndBlock` to `x/evm/abci.go`
+
+## Features
+
+* (rpc) [\#231](https://github.com/ChainSafe/ethermint/issues/231) Implement NewBlockFilter in rpc/filters.go which instantiates a polling block filter
+	* Polls for new blocks via BlockNumber rpc call; if block number changes, it requests the new block via GetBlockByNumber rpc call and adds it to its internal list of blocks
+	* Update uninstallFilter and getFilterChanges accordingly
+	* uninstallFilter stops the polling goroutine
+	* getFilterChanges returns the filter's internal list of block hashes and resets it

rpc/filter_api.go

@@ -52,7 +52,6 @@ func (e *PublicFilterAPI) NewPendingTransactionFilter() rpc.ID {
 
 // UninstallFilter uninstalls a filter with the given ID.
 func (e *PublicFilterAPI) UninstallFilter(id rpc.ID) bool {
-	// TODO
 	e.filters[id].uninstallFilter()
 	delete(e.filters, id)
 	return true
@@ -62,7 +61,7 @@ func (e *PublicFilterAPI) UninstallFilter(id rpc.ID) bool {
 // If the filter is a log filter, it returns an array of Logs.
 // If the filter is a block filter, it returns an array of block hashes.
 // If the filter is a pending transaction filter, it returns an array of transaction hashes.
-func (e *PublicFilterAPI) GetFilterChanges(id rpc.ID) interface{} {
+func (e *PublicFilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error) {
 	return e.filters[id].getFilterChanges()
 }
 

rpc/filters.go

@@ -1,9 +1,11 @@
 package rpc
 
 import (
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth/filters"
 )
@@ -13,13 +15,24 @@ import (
 	Used to set the criteria passed in from RPC params
 */
 
-// Filter can be used to retrieve and filter logs.
+const blockFilter = "block"
+const pendingTxFilter = "pending"
+const logFilter = "log"
+
+// Filter can be used to retrieve and filter logs, blocks, or pending transactions.
 type Filter struct {
 	backend            Backend
 	fromBlock, toBlock *big.Int         // start and end block numbers
 	addresses          []common.Address // contract addresses to watch
 	topics             [][]common.Hash  // log topics to watch for
 	blockHash          *common.Hash     // Block hash if filtering a single block
+
+	typ     string
+	hashes  []common.Hash   // filtered block or transaction hashes
+	logs    []*ethtypes.Log //nolint // filtered logs
+	stopped bool            // set to true once filter in uninstalled
+
+	err error
 }
 
 // NewFilter returns a new Filter
@@ -30,6 +43,8 @@ func NewFilter(backend Backend, criteria *filters.FilterCriteria) *Filter {
 		toBlock:   criteria.ToBlock,
 		addresses: criteria.Addresses,
 		topics:    criteria.Topics,
+		typ:       logFilter,
+		stopped:   false,
 	}
 }
 
@@ -42,33 +57,92 @@ func NewFilterWithBlockHash(backend Backend, criteria *filters.FilterCriteria) *
 		addresses: criteria.Addresses,
 		topics:    criteria.Topics,
 		blockHash: criteria.BlockHash,
+		typ:       logFilter,
 	}
 }
 
 // NewBlockFilter creates a new filter that notifies when a block arrives.
 func NewBlockFilter(backend Backend) *Filter {
-	// TODO: finish
-	filter := NewFilter(backend, nil)
+	filter := NewFilter(backend, &filters.FilterCriteria{})
+	filter.typ = blockFilter
+
+	go func() {
+		err := filter.pollForBlocks()
+		if err != nil {
+			filter.err = err
+		}
+	}()
+
 	return filter
 }
 
+func (f *Filter) pollForBlocks() error {
+	prev := hexutil.Uint64(0)
+
+	for {
+		if f.stopped {
+			return nil
+		}
+
+		num, err := f.backend.BlockNumber()
+		if err != nil {
+			return err
+		}
+
+		if num == prev {
+			continue
+		}
+
+		block, err := f.backend.GetBlockByNumber(BlockNumber(num), false)
+		if err != nil {
+			return err
+		}
+
+		hashBytes, ok := block["hash"].(hexutil.Bytes)
+		if !ok {
+			return errors.New("could not convert block hash to hexutil.Bytes")
+		}
+
+		hash := common.BytesToHash([]byte(hashBytes))
+		f.hashes = append(f.hashes, hash)
+
+		prev = num
+
+		// TODO: should we add a delay?
+	}
+}
+
 // NewPendingTransactionFilter creates a new filter that notifies when a pending transaction arrives.
 func NewPendingTransactionFilter(backend Backend) *Filter {
 	// TODO: finish
 	filter := NewFilter(backend, nil)
+	filter.typ = pendingTxFilter
 	return filter
 }
 
 func (f *Filter) uninstallFilter() {
-	// TODO
+	f.stopped = true
 }
 
-func (f *Filter) getFilterChanges() interface{} {
+func (f *Filter) getFilterChanges() (interface{}, error) {
+	switch f.typ {
+	case blockFilter:
+		if f.err != nil {
+			return nil, f.err
+		}
+
+		blocks := make([]common.Hash, len(f.hashes))
+		copy(blocks, f.hashes)
+		f.hashes = []common.Hash{}
+
+		return blocks, nil
+	case pendingTxFilter:
 		// TODO
-	// we might want to use an interface for Filters themselves because of this function, it may return an array of logs
-	// or an array of hashes, depending of whether Filter is a log filter or a block/transaction filter.
-	// or, we can add a type field to Filter.
-	return nil
+	case logFilter:
+		// TODO
+	}
+
+	return nil, nil
 }
 
 func (f *Filter) getFilterLogs() []*ethtypes.Log {

rpc/tester/tester_test.go

@@ -33,7 +33,7 @@ var addr = fmt.Sprintf("http://%s:%d", host, port)
 type Request struct {
 	Version string      `json:"jsonrpc"`
 	Method  string      `json:"method"`
-	Params  []string `json:"params"`
+	Params  interface{} `json:"params"`
 	ID      int         `json:"id"`
 }
 
@@ -49,7 +49,7 @@ type Response struct {
 	Result json.RawMessage `json:"result,omitempty"`
 }
 
-func createRequest(method string, params []string) Request {
+func createRequest(method string, params interface{}) Request {
 	return Request{
 		Version: "2.0",
 		Method:  method,
@@ -58,7 +58,7 @@ func createRequest(method string, params []string) Request {
 	}
 }
 
-func call(method string, params []string) (*Response, error) {
+func call(t *testing.T, method string, params interface{}) (*Response, error) {
 	req, err := json.Marshal(createRequest(method, params))
 	if err != nil {
 		return nil, err
@@ -67,23 +67,23 @@ func call(method string, params []string) (*Response, error) {
 	/* #nosec */
 	res, err := http.Post(addr, "application/json", bytes.NewBuffer(req))
 	if err != nil {
-		return nil, err
+		t.Fatal(err)
 	}
 
 	decoder := json.NewDecoder(res.Body)
 	var rpcRes *Response
 	err = decoder.Decode(&rpcRes)
 	if err != nil {
-		return nil, err
+		t.Fatal(err)
 	}
 
 	if rpcRes.Error != nil {
-		return nil, errors.New(rpcRes.Error.Message)
+		t.Fatal(errors.New(rpcRes.Error.Message))
 	}
 
 	err = res.Body.Close()
 	if err != nil {
-		return nil, err
+		t.Fatal(err)
 	}
 
 	return rpcRes, nil
@@ -92,7 +92,7 @@ func call(method string, params []string) (*Response, error) {
 func TestEth_protocolVersion(t *testing.T) {
 	expectedRes := hexutil.Uint(version.ProtocolVersion)
 
-	rpcRes, err := call("eth_protocolVersion", []string{})
+	rpcRes, err := call(t, "eth_protocolVersion", []string{})
 	require.NoError(t, err)
 
 	var res hexutil.Uint
@@ -104,7 +104,7 @@ func TestEth_protocolVersion(t *testing.T) {
 }
 
 func TestEth_blockNumber(t *testing.T) {
-	rpcRes, err := call("eth_blockNumber", []string{})
+	rpcRes, err := call(t, "eth_blockNumber", []string{})
 	require.NoError(t, err)
 
 	var res hexutil.Uint64
@@ -115,7 +115,7 @@ func TestEth_blockNumber(t *testing.T) {
 }
 
 func TestEth_GetBalance(t *testing.T) {
-	rpcRes, err := call("eth_getBalance", []string{addrA, "0x0"})
+	rpcRes, err := call(t, "eth_getBalance", []string{addrA, "0x0"})
 	require.NoError(t, err)
 
 	var res hexutil.Big
@@ -132,7 +132,7 @@ func TestEth_GetBalance(t *testing.T) {
 
 func TestEth_GetStorageAt(t *testing.T) {
 	expectedRes := hexutil.Bytes{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
-	rpcRes, err := call("eth_getStorageAt", []string{addrA, string(addrAStoreKey), "0x0"})
+	rpcRes, err := call(t, "eth_getStorageAt", []string{addrA, string(addrAStoreKey), "0x0"})
 	require.NoError(t, err)
 
 	var storage hexutil.Bytes
@@ -146,7 +146,7 @@ func TestEth_GetStorageAt(t *testing.T) {
 
 func TestEth_GetCode(t *testing.T) {
 	expectedRes := hexutil.Bytes{}
-	rpcRes, err := call("eth_getCode", []string{addrA, "0x0"})
+	rpcRes, err := call(t, "eth_getCode", []string{addrA, "0x0"})
 	require.NoError(t, err)
 
 	var code hexutil.Bytes
@@ -157,3 +157,15 @@ func TestEth_GetCode(t *testing.T) {
 	t.Logf("Got code [%X] for %s\n", code, addrA)
 	require.True(t, bytes.Equal(expectedRes, code), "expected: %X got: %X", expectedRes, code)
 }
+
+func TestEth_NewFilter(t *testing.T) {
+	param := make([]map[string][]string, 1)
+	param[0] = make(map[string][]string)
+	param[0]["topics"] = []string{"0x0000000000000000000000000000000000000000000000000000000012341234"}
+	rpcRes, err := call(t, "eth_newFilter", param)
+	require.NoError(t, err)
+
+	var code hexutil.Bytes
+	err = code.UnmarshalJSON(rpcRes.Result)
+	require.NoError(t, err)
+}

x/evm/client/cli/query.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/context"
+	"github.com/cosmos/cosmos-sdk/client/flags"
 	"github.com/cosmos/cosmos-sdk/codec"
 
 	"github.com/cosmos/ethermint/x/evm/types"
@@ -22,7 +23,7 @@ func GetQueryCmd(moduleName string, cdc *codec.Codec) *cobra.Command {
 		SuggestionsMinimumDistance: 2,
 		RunE:                       client.ValidateCmd,
 	}
-	evmQueryCmd.AddCommand(client.GetCommands(
+	evmQueryCmd.AddCommand(flags.GetCommands(
 		GetCmdGetStorageAt(moduleName, cdc),
 		GetCmdGetCode(moduleName, cdc),
 	)...)

x/evm/client/cli/tx.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/context"
+	"github.com/cosmos/cosmos-sdk/client/flags"
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
@@ -33,7 +34,7 @@ func GetTxCmd(storeKey string, cdc *codec.Codec) *cobra.Command {
 		RunE:                       client.ValidateCmd,
 	}
 
-	evmTxCmd.AddCommand(client.PostCommands(
+	evmTxCmd.AddCommand(flags.PostCommands(
 		GetCmdGenTx(cdc),
 		GetCmdGenCreateTx(cdc),
 	)...)
@@ -73,7 +74,7 @@ func GetCmdGenTx(cdc *codec.Codec) *cobra.Command {
 
 				data, err = hexutil.Decode(payload)
 				if err != nil {
-					fmt.Println(err)
+					return err
 				}
 			}
 
@@ -117,7 +118,7 @@ func GetCmdGenCreateTx(cdc *codec.Codec) *cobra.Command {
 
 			data, err := hexutil.Decode(payload)
 			if err != nil {
-				fmt.Println(err)
+				return err
 			}
 
 			var amount int64

x/evm/keeper/keeper.go

@@ -97,10 +97,6 @@ func (k *Keeper) GetBlockBloomMapping(ctx sdk.Context, height int64) (ethtypes.B
 	}
 
 	bloom := store.Get(types.BloomKey(bz))
-	if len(bloom) == 0 {
-		return ethtypes.BytesToBloom([]byte{}), fmt.Errorf("block with bloombits %v not found", bloom)
-	}
-
 	return ethtypes.BytesToBloom(bloom), nil
 }