Implementation for newPendingTransactions (eth_subscribe) (#1787)

* Implementation for  newPendingTransactions(eth_subscribe)

jsonrpc/dispatcher.go

@@ -209,6 +209,8 @@ func (d *Dispatcher) handleSubscribe(req Request, conn wsConn) (string, Error) {
 			return "", NewInternalError(err.Error())
 		}
 		filterID = d.filterManager.NewLogFilter(logQuery, conn)
+	} else if subscribeMethod == "newPendingTransactions" {
+		filterID = d.filterManager.NewPendingTxFilter(conn)
 	} else {
 		return "", NewSubscriptionNotFoundError(subscribeMethod)
 	}

jsonrpc/dispatcher_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/0xPolygon/polygon-edge/txpool/proto"
 	"github.com/0xPolygon/polygon-edge/types"
 	"github.com/hashicorp/go-hclog"
 	"github.com/stretchr/testify/assert"
@@ -60,29 +61,29 @@ func expectBatchJSONResult(data []byte, v interface{}) error {
 func TestDispatcher_HandleWebsocketConnection_EthSubscribe(t *testing.T) {
 	t.Parallel()
 
-	t.Run("clients should be able to receive \"newHeads\" event thru eth_subscribe", func(t *testing.T) {
+	store := newMockStore()
+	dispatcher := newTestDispatcher(t,
+		hclog.NewNullLogger(),
+		store,
+		&dispatcherParams{
+			chainID:                 0,
+			priceLimit:              0,
+			jsonRPCBatchLengthLimit: 20,
+			blockRangeLimit:         1000,
+		},
+	)
+
+	t.Run("clients should be able to receive \"newHeads\" event through eth_subscribe", func(t *testing.T) {
 		t.Parallel()
 
-		store := newMockStore()
-		dispatcher := newTestDispatcher(t,
-			hclog.NewNullLogger(),
-			store,
-			&dispatcherParams{
-				chainID:                 0,
-				priceLimit:              0,
-				jsonRPCBatchLengthLimit: 20,
-				blockRangeLimit:         1000,
-			},
-		)
 		mockConnection, msgCh := newMockWsConnWithMsgCh()
 
 		req := []byte(`{
 		"method": "eth_subscribe",
 		"params": ["newHeads"]
 	}`)
-		if _, err := dispatcher.HandleWs(req, mockConnection); err != nil {
-			t.Fatal(err)
-		}
+		_, err := dispatcher.HandleWs(req, mockConnection)
+		require.NoError(t, err)
 
 		store.emitEvent(&mockEvent{
 			NewChain: []*mockHeader{
@@ -100,6 +101,27 @@ func TestDispatcher_HandleWebsocketConnection_EthSubscribe(t *testing.T) {
 			t.Fatal("\"newHeads\" event not received in 2 seconds")
 		}
 	})
+
+	t.Run("clients should be able to receive \"newPendingTransactions\" event through eth_subscribe", func(t *testing.T) {
+		t.Parallel()
+
+		mockConnection, msgCh := newMockWsConnWithMsgCh()
+
+		req := []byte(`{
+		"method": "eth_subscribe",
+		"params": ["newPendingTransactions"]
+	}`)
+		_, err := dispatcher.HandleWs(req, mockConnection)
+		require.NoError(t, err)
+
+		store.emitTxPoolEvent(proto.EventType_ADDED, "evt1")
+
+		select {
+		case <-msgCh:
+		case <-time.After(2 * time.Second):
+			t.Fatal("\"newPendingTransactions\" event not received in 2 seconds")
+		}
+	})
 }
 
 func TestDispatcher_WebsocketConnection_RequestFormats(t *testing.T) {
@@ -289,7 +311,7 @@ func TestDispatcherFuncDecode(t *testing.T) {
 	for _, c := range cases {
 		res := handleReq(c.typ, c.msg)
 		if !reflect.DeepEqual(res, c.res) {
-			t.Fatal("bad")
+			t.Fatal("no tx pool events received in the predefined time slot")
 		}
 	}
 }

jsonrpc/eth_blockchain_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/0xPolygon/polygon-edge/helper/hex"
 	"github.com/0xPolygon/polygon-edge/helper/progress"
 	"github.com/0xPolygon/polygon-edge/state/runtime"
+	"github.com/0xPolygon/polygon-edge/txpool/proto"
 	"github.com/0xPolygon/polygon-edge/types"
 	"github.com/stretchr/testify/assert"
 )
@@ -589,6 +590,10 @@ func (m *mockBlockStore) FilterExtra(extra []byte) ([]byte, error) {
 	return extra, nil
 }
 
+func (m *mockBlockStore) TxPoolSubscribe(request *proto.SubscribeRequest) (<-chan *proto.TxPoolEvent, func(), error) {
+	return nil, nil, nil
+}
+
 func newTestBlock(number uint64, hash types.Hash) *types.Block {
 	return &types.Block{
 		Header: &types.Header{

jsonrpc/filter_manager.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/0xPolygon/polygon-edge/blockchain"
+	"github.com/0xPolygon/polygon-edge/txpool/proto"
 	"github.com/0xPolygon/polygon-edge/types"
 	"github.com/google/uuid"
 	"github.com/gorilla/websocket"
@@ -25,6 +26,7 @@ var (
 	ErrIncorrectBlockRange              = errors.New("incorrect range")
 	ErrBlockRangeTooHigh                = errors.New("block range too high")
 	ErrNoWSConnection                   = errors.New("no websocket connection")
+	ErrUnknownSubscriptionType          = errors.New("unknown subscription type")
 )
 
 // defaultTimeout is the timeout to remove the filters that don't have a web socket stream
@@ -35,6 +37,16 @@ const (
 	NoIndexInHeap = -1
 )
 
+// subscriptionType determines which event type the filter is subscribed to
+type subscriptionType byte
+
+const (
+	// Blocks represents subscription type for blockchain events
+	Blocks subscriptionType = iota
+	// PendingTransactions represents subscription type for tx pool events
+	PendingTransactions
+)
+
 // filter is an interface that BlockFilter and LogFilter implement
 type filter interface {
 	// hasWSConn returns the flag indicating the filter has web socket stream
@@ -43,6 +55,9 @@ type filter interface {
 	// getFilterBase returns filterBase that has common fields
 	getFilterBase() *filterBase
 
+	// getSubscriptionType returns the type of the event the filter is subscribed to
+	getSubscriptionType() subscriptionType
+
 	// getUpdates returns stored data in a JSON serializable form
 	getUpdates() (interface{}, error)
 
@@ -159,6 +174,11 @@ func (f *blockFilter) sendUpdates() error {
 	return nil
 }
 
+// getSubscriptionType returns the type of the event the filter is subscribed to
+func (f *blockFilter) getSubscriptionType() subscriptionType {
+	return Blocks
+}
+
 // logFilter is a filter to store logs that meet the conditions in query
 type logFilter struct {
 	filterBase
@@ -212,6 +232,63 @@ func (f *logFilter) sendUpdates() error {
 	return nil
 }
 
+// getSubscriptionType returns the type of the event the filter is subscribed to
+func (f *logFilter) getSubscriptionType() subscriptionType {
+	return Blocks
+}
+
+// pendingTxFilter is a filter to store pending tx
+type pendingTxFilter struct {
+	filterBase
+	sync.Mutex
+
+	txHashes []string
+}
+
+// appendPendingTxHashes appends new pending tx hash to tx hashes
+func (f *pendingTxFilter) appendPendingTxHashes(txHash string) {
+	f.Lock()
+	defer f.Unlock()
+
+	f.txHashes = append(f.txHashes, txHash)
+}
+
+// takePendingTxsUpdates returns all saved pending tx hashes in filter and sets a new slice
+func (f *pendingTxFilter) takePendingTxsUpdates() []string {
+	f.Lock()
+	defer f.Unlock()
+
+	txHashes := f.txHashes
+	f.txHashes = []string{}
+
+	return txHashes
+}
+
+// getSubscriptionType returns the type of the event the filter is subscribed to
+func (f *pendingTxFilter) getSubscriptionType() subscriptionType {
+	return PendingTransactions
+}
+
+// getUpdates returns stored pending tx hashes
+func (f *pendingTxFilter) getUpdates() (interface{}, error) {
+	pendingTxHashes := f.takePendingTxsUpdates()
+
+	return pendingTxHashes, nil
+}
+
+// sendUpdates write the hashes for all pending transactions to web socket stream
+func (f *pendingTxFilter) sendUpdates() error {
+	pendingTxHashes := f.takePendingTxsUpdates()
+
+	for _, txHash := range pendingTxHashes {
+		if err := f.writeMessageToWs(txHash); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 // filterManagerStore provides methods required by FilterManager
 type filterManagerStore interface {
 	// Header returns the current header of the chain (genesis if empty)
@@ -228,6 +305,9 @@ type filterManagerStore interface {
 
 	// GetBlockByNumber returns a block using the provided number
 	GetBlockByNumber(num uint64, full bool) (*types.Block, bool)
+
+	// TxPoolSubscribe subscribes for tx pool events
+	TxPoolSubscribe(request *proto.SubscribeRequest) (<-chan *proto.TxPoolEvent, func(), error)
 }
 
 // FilterManager manages all running filters
@@ -279,18 +359,32 @@ func NewFilterManager(logger hclog.Logger, store filterManagerStore, blockRangeL
 // Run starts worker process to handle events
 func (f *FilterManager) Run() {
 	// watch for new events in the blockchain
-	watchCh := make(chan *blockchain.Event)
+	blockWatchCh := make(chan *blockchain.Event)
 
 	go func() {
 		for {
 			evnt := f.subscription.GetEvent()
 			if evnt == nil {
 				return
 			}
-			watchCh <- evnt
+			blockWatchCh <- evnt
 		}
 	}()
 
+	// watch for new events in the tx pool
+	txRequest := &proto.SubscribeRequest{
+		Types: []proto.EventType{proto.EventType_ADDED},
+	}
+
+	txWatchCh, txPoolUnsubscribe, err := f.store.TxPoolSubscribe(txRequest)
+	if err != nil {
+		f.logger.Error("Unable to subscribe to tx pool")
+
+		return
+	}
+
+	defer txPoolUnsubscribe()
+
 	var timeoutCh <-chan time.Time
 
 	for {
@@ -303,10 +397,16 @@ func (f *FilterManager) Run() {
 		}
 
 		select {
-		case evnt := <-watchCh:
+		case evnt := <-blockWatchCh:
 			// new blockchain event
 			if err := f.dispatchEvent(evnt); err != nil {
-				f.logger.Error("failed to dispatch event", "err", err)
+				f.logger.Error("failed to dispatch block event", "err", err)
+			}
+
+		case evnt := <-txWatchCh:
+			// new tx pool event
+			if err := f.dispatchEvent(evnt); err != nil {
+				f.logger.Error("failed to dispatch tx pool event", "err", err)
 			}
 
 		case <-timeoutCh:
@@ -359,6 +459,20 @@ func (f *FilterManager) NewLogFilter(logQuery *LogQuery, ws wsConn) string {
 	return f.addFilter(filter)
 }
 
+// NewPendingTxFilter adds new PendingTxFilter
+func (f *FilterManager) NewPendingTxFilter(ws wsConn) string {
+	filter := &pendingTxFilter{
+		filterBase: newFilterBase(ws),
+		txHashes:   []string{},
+	}
+
+	if filter.hasWSConn() {
+		ws.SetFilterID(filter.id)
+	}
+
+	return f.addFilter(filter)
+}
+
 // Exists checks the filter with given ID exists
 func (f *FilterManager) Exists(id string) bool {
 	f.RLock()
@@ -621,20 +735,34 @@ func (f *FilterManager) nextTimeoutFilter() (string, time.Time) {
 }
 
 // dispatchEvent is an event handler for new block event
-func (f *FilterManager) dispatchEvent(evnt *blockchain.Event) error {
+func (f *FilterManager) dispatchEvent(evnt interface{}) error {
+	var subType subscriptionType
+
 	// store new event in each filters
-	f.processEvent(evnt)
+	switch evt := evnt.(type) {
+	case *blockchain.Event:
+		f.processBlockEvent(evt)
+
+		subType = Blocks
+	case *proto.TxPoolEvent:
+		f.processTxEvent(evt)
+
+		subType = PendingTransactions
+
+	default:
+		return ErrUnknownSubscriptionType
+	}
 
 	// send data to web socket stream
-	if err := f.flushWsFilters(); err != nil {
+	if err := f.flushWsFilters(subType); err != nil {
 		return err
 	}
 
 	return nil
 }
 
 // processEvent makes each filter append the new data that interests them
-func (f *FilterManager) processEvent(evnt *blockchain.Event) {
+func (f *FilterManager) processBlockEvent(evnt *blockchain.Event) {
 	f.RLock()
 	defer f.RUnlock()
 
@@ -710,15 +838,27 @@ func (f *FilterManager) appendLogsToFilters(header *block) error {
 	return nil
 }
 
+// processTxEvent makes each filter refresh the pending tx hashes
+func (f *FilterManager) processTxEvent(evnt *proto.TxPoolEvent) {
+	f.RLock()
+	defer f.RUnlock()
+
+	for _, f := range f.filters {
+		if txFilter, ok := f.(*pendingTxFilter); ok {
+			txFilter.appendPendingTxHashes(evnt.TxHash)
+		}
+	}
+}
+
 // flushWsFilters make each filters with web socket connection write the updates to web socket stream
 // flushWsFilters also removes the filters if flushWsFilters notices the connection is closed
-func (f *FilterManager) flushWsFilters() error {
+func (f *FilterManager) flushWsFilters(subType subscriptionType) error {
 	closedFilterIDs := make([]string, 0)
 
 	f.RLock()
 
 	for id, filter := range f.filters {
-		if !filter.hasWSConn() {
+		if !filter.hasWSConn() || filter.getSubscriptionType() != subType {
 			continue
 		}