eth/filters, ethclient/gethclient: add fullTx option to pending tx filter (#25186)

This PR adds a way to subscribe to the _full_ pending transactions, as opposed to just being notified about hashes. 

In use cases where client subscribes to newPendingTransactions and gets txhashes only to then request the actual transaction, the caller can now shortcut that flow and obtain the transactions directly. 
Co-authored-by: Felix Lange <fjl@twurst.com>

eth/filters/api.go

@@ -38,6 +38,7 @@ type filter struct {
 	typ      Type
 	deadline *time.Timer // filter is inactive when deadline triggers
 	hashes   []common.Hash
+	txs      []*types.Transaction
 	crit     FilterCriteria
 	logs     []*types.Log
 	s        *Subscription // associated subscription in event system
@@ -96,28 +97,28 @@ func (api *FilterAPI) timeoutLoop(timeout time.Duration) {
 	}
 }
 
-// NewPendingTransactionFilter creates a filter that fetches pending transaction hashes
+// NewPendingTransactionFilter creates a filter that fetches pending transactions
 // as transactions enter the pending state.
 //
 // It is part of the filter package because this filter can be used through the
 // `eth_getFilterChanges` polling method that is also used for log filters.
 func (api *FilterAPI) NewPendingTransactionFilter() rpc.ID {
 	var (
-		pendingTxs   = make(chan []common.Hash)
+		pendingTxs   = make(chan []*types.Transaction)
 		pendingTxSub = api.events.SubscribePendingTxs(pendingTxs)
 	)
 
 	api.filtersMu.Lock()
-	api.filters[pendingTxSub.ID] = &filter{typ: PendingTransactionsSubscription, deadline: time.NewTimer(api.timeout), hashes: make([]common.Hash, 0), s: pendingTxSub}
+	api.filters[pendingTxSub.ID] = &filter{typ: PendingTransactionsSubscription, deadline: time.NewTimer(api.timeout), txs: make([]*types.Transaction, 0), s: pendingTxSub}
 	api.filtersMu.Unlock()
 
 	go func() {
 		for {
 			select {
-			case ph := <-pendingTxs:
+			case pTx := <-pendingTxs:
 				api.filtersMu.Lock()
 				if f, found := api.filters[pendingTxSub.ID]; found {
-					f.hashes = append(f.hashes, ph...)
+					f.txs = append(f.txs, pTx...)
 				}
 				api.filtersMu.Unlock()
 			case <-pendingTxSub.Err():
@@ -132,9 +133,10 @@ func (api *FilterAPI) NewPendingTransactionFilter() rpc.ID {
 	return pendingTxSub.ID
 }
 
-// NewPendingTransactions creates a subscription that is triggered each time a transaction
-// enters the transaction pool and was signed from one of the transactions this nodes manages.
-func (api *FilterAPI) NewPendingTransactions(ctx context.Context) (*rpc.Subscription, error) {
+// NewPendingTransactions creates a subscription that is triggered each time a
+// transaction enters the transaction pool. If fullTx is true the full tx is
+// sent to the client, otherwise the hash is sent.
+func (api *FilterAPI) NewPendingTransactions(ctx context.Context, fullTx *bool) (*rpc.Subscription, error) {
 	notifier, supported := rpc.NotifierFromContext(ctx)
 	if !supported {
 		return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
@@ -143,16 +145,20 @@ func (api *FilterAPI) NewPendingTransactions(ctx context.Context) (*rpc.Subscrip
 	rpcSub := notifier.CreateSubscription()
 
 	go func() {
-		txHashes := make(chan []common.Hash, 128)
-		pendingTxSub := api.events.SubscribePendingTxs(txHashes)
+		txs := make(chan []*types.Transaction, 128)
+		pendingTxSub := api.events.SubscribePendingTxs(txs)
 
 		for {
 			select {
-			case hashes := <-txHashes:
+			case txs := <-txs:
 				// To keep the original behaviour, send a single tx hash in one notification.
 				// TODO(rjl493456442) Send a batch of tx hashes in one notification
-				for _, h := range hashes {
-					notifier.Notify(rpcSub.ID, h)
+				for _, tx := range txs {
+					if fullTx != nil && *fullTx {
+						notifier.Notify(rpcSub.ID, tx)
+					} else {
+						notifier.Notify(rpcSub.ID, tx.Hash())
+					}
 				}
 			case <-rpcSub.Err():
 				pendingTxSub.Unsubscribe()
@@ -411,10 +417,14 @@ func (api *FilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error) {
 		f.deadline.Reset(api.timeout)
 
 		switch f.typ {
-		case PendingTransactionsSubscription, BlocksSubscription:
+		case BlocksSubscription:
 			hashes := f.hashes
 			f.hashes = nil
 			return returnHashes(hashes), nil
+		case PendingTransactionsSubscription:
+			txs := f.txs
+			f.txs = nil
+			return txs, nil
 		case LogsSubscription, MinedAndPendingLogsSubscription:
 			logs := f.logs
 			f.logs = nil

eth/filters/filter_system.go

@@ -124,8 +124,8 @@ const (
 	PendingLogsSubscription
 	// MinedAndPendingLogsSubscription queries for logs in mined and pending blocks.
 	MinedAndPendingLogsSubscription
-	// PendingTransactionsSubscription queries tx hashes for pending
-	// transactions entering the pending state
+	// PendingTransactionsSubscription queries for pending transactions entering
+	// the pending state
 	PendingTransactionsSubscription
 	// BlocksSubscription queries hashes for blocks that are imported
 	BlocksSubscription
@@ -151,7 +151,7 @@ type subscription struct {
 	created   time.Time
 	logsCrit  ethereum.FilterQuery
 	logs      chan []*types.Log
-	hashes    chan []common.Hash
+	txs       chan []*types.Transaction
 	headers   chan *types.Header
 	installed chan struct{} // closed when the filter is installed
 	err       chan error    // closed when the filter is uninstalled
@@ -244,7 +244,7 @@ func (sub *Subscription) Unsubscribe() {
 			case sub.es.uninstall <- sub.f:
 				break uninstallLoop
 			case <-sub.f.logs:
-			case <-sub.f.hashes:
+			case <-sub.f.txs:
 			case <-sub.f.headers:
 			}
 		}
@@ -311,7 +311,7 @@ func (es *EventSystem) subscribeMinedPendingLogs(crit ethereum.FilterQuery, logs
 		logsCrit:  crit,
 		created:   time.Now(),
 		logs:      logs,
-		hashes:    make(chan []common.Hash),
+		txs:       make(chan []*types.Transaction),
 		headers:   make(chan *types.Header),
 		installed: make(chan struct{}),
 		err:       make(chan error),
@@ -328,7 +328,7 @@ func (es *EventSystem) subscribeLogs(crit ethereum.FilterQuery, logs chan []*typ
 		logsCrit:  crit,
 		created:   time.Now(),
 		logs:      logs,
-		hashes:    make(chan []common.Hash),
+		txs:       make(chan []*types.Transaction),
 		headers:   make(chan *types.Header),
 		installed: make(chan struct{}),
 		err:       make(chan error),
@@ -345,7 +345,7 @@ func (es *EventSystem) subscribePendingLogs(crit ethereum.FilterQuery, logs chan
 		logsCrit:  crit,
 		created:   time.Now(),
 		logs:      logs,
-		hashes:    make(chan []common.Hash),
+		txs:       make(chan []*types.Transaction),
 		headers:   make(chan *types.Header),
 		installed: make(chan struct{}),
 		err:       make(chan error),
@@ -361,7 +361,7 @@ func (es *EventSystem) SubscribeNewHeads(headers chan *types.Header) *Subscripti
 		typ:       BlocksSubscription,
 		created:   time.Now(),
 		logs:      make(chan []*types.Log),
-		hashes:    make(chan []common.Hash),
+		txs:       make(chan []*types.Transaction),
 		headers:   headers,
 		installed: make(chan struct{}),
 		err:       make(chan error),
@@ -369,15 +369,15 @@ func (es *EventSystem) SubscribeNewHeads(headers chan *types.Header) *Subscripti
 	return es.subscribe(sub)
 }
 
-// SubscribePendingTxs creates a subscription that writes transaction hashes for
+// SubscribePendingTxs creates a subscription that writes transactions for
 // transactions that enter the transaction pool.
-func (es *EventSystem) SubscribePendingTxs(hashes chan []common.Hash) *Subscription {
+func (es *EventSystem) SubscribePendingTxs(txs chan []*types.Transaction) *Subscription {
 	sub := &subscription{
 		id:        rpc.NewID(),
 		typ:       PendingTransactionsSubscription,
 		created:   time.Now(),
 		logs:      make(chan []*types.Log),
-		hashes:    hashes,
+		txs:       txs,
 		headers:   make(chan *types.Header),
 		installed: make(chan struct{}),
 		err:       make(chan error),
@@ -421,12 +421,8 @@ func (es *EventSystem) handleRemovedLogs(filters filterIndex, ev core.RemovedLog
 }
 
 func (es *EventSystem) handleTxsEvent(filters filterIndex, ev core.NewTxsEvent) {
-	hashes := make([]common.Hash, 0, len(ev.Txs))
-	for _, tx := range ev.Txs {
-		hashes = append(hashes, tx.Hash())
-	}
 	for _, f := range filters[PendingTransactionsSubscription] {
-		f.hashes <- hashes
+		f.txs <- ev.Txs
 	}
 }
 

eth/filters/filter_system_test.go

@@ -240,7 +240,7 @@ func TestPendingTxFilter(t *testing.T) {
 			types.NewTransaction(4, common.HexToAddress("0xb794f5ea0ba39494ce83a213fffba74279579268"), new(big.Int), 0, new(big.Int), nil),
 		}
 
-		hashes []common.Hash
+		txs []*types.Transaction
 	)
 
 	fid0 := api.NewPendingTransactionFilter()
@@ -255,9 +255,9 @@ func TestPendingTxFilter(t *testing.T) {
 			t.Fatalf("Unable to retrieve logs: %v", err)
 		}
 
-		h := results.([]common.Hash)
-		hashes = append(hashes, h...)
-		if len(hashes) >= len(transactions) {
+		tx := results.([]*types.Transaction)
+		txs = append(txs, tx...)
+		if len(txs) >= len(transactions) {
 			break
 		}
 		// check timeout
@@ -268,13 +268,13 @@ func TestPendingTxFilter(t *testing.T) {
 		time.Sleep(100 * time.Millisecond)
 	}
 
-	if len(hashes) != len(transactions) {
-		t.Errorf("invalid number of transactions, want %d transactions(s), got %d", len(transactions), len(hashes))
+	if len(txs) != len(transactions) {
+		t.Errorf("invalid number of transactions, want %d transactions(s), got %d", len(transactions), len(txs))
 		return
 	}
-	for i := range hashes {
-		if hashes[i] != transactions[i].Hash() {
-			t.Errorf("hashes[%d] invalid, want %x, got %x", i, transactions[i].Hash(), hashes[i])
+	for i := range txs {
+		if txs[i].Hash() != transactions[i].Hash() {
+			t.Errorf("hashes[%d] invalid, want %x, got %x", i, transactions[i].Hash(), txs[i].Hash())
 		}
 	}
 }
@@ -705,11 +705,11 @@ func TestPendingTxFilterDeadlock(t *testing.T) {
 		fids[i] = fid
 		// Wait for at least one tx to arrive in filter
 		for {
-			hashes, err := api.GetFilterChanges(fid)
+			txs, err := api.GetFilterChanges(fid)
 			if err != nil {
 				t.Fatalf("Filter should exist: %v\n", err)
 			}
-			if len(hashes.([]common.Hash)) > 0 {
+			if len(txs.([]*types.Transaction)) > 0 {
 				break
 			}
 			runtime.Gosched()

ethclient/gethclient/gethclient.go

@@ -166,7 +166,12 @@ func (ec *Client) GetNodeInfo(ctx context.Context) (*p2p.NodeInfo, error) {
 	return &result, err
 }
 
-// SubscribePendingTransactions subscribes to new pending transactions.
+// SubscribeFullPendingTransactions subscribes to new pending transactions.
+func (ec *Client) SubscribeFullPendingTransactions(ctx context.Context, ch chan<- *types.Transaction) (*rpc.ClientSubscription, error) {
+	return ec.c.EthSubscribe(ctx, ch, "newPendingTransactions", true)
+}
+
+// SubscribePendingTransactions subscribes to new pending transaction hashes.
 func (ec *Client) SubscribePendingTransactions(ctx context.Context, ch chan<- common.Hash) (*rpc.ClientSubscription, error) {
 	return ec.c.EthSubscribe(ctx, ch, "newPendingTransactions")
 }

ethclient/gethclient/gethclient_test.go

@@ -122,8 +122,11 @@ func TestGethClient(t *testing.T) {
 			"TestSetHead",
 			func(t *testing.T) { testSetHead(t, client) },
 		}, {
-			"TestSubscribePendingTxs",
+			"TestSubscribePendingTxHashes",
 			func(t *testing.T) { testSubscribePendingTransactions(t, client) },
+		}, {
+			"TestSubscribePendingTxs",
+			func(t *testing.T) { testSubscribeFullPendingTransactions(t, client) },
 		}, {
 			"TestCallContract",
 			func(t *testing.T) { testCallContract(t, client) },
@@ -303,6 +306,40 @@ func testSubscribePendingTransactions(t *testing.T, client *rpc.Client) {
 	}
 }
 
+func testSubscribeFullPendingTransactions(t *testing.T, client *rpc.Client) {
+	ec := New(client)
+	ethcl := ethclient.NewClient(client)
+	// Subscribe to Transactions
+	ch := make(chan *types.Transaction)
+	ec.SubscribeFullPendingTransactions(context.Background(), ch)
+	// Send a transaction
+	chainID, err := ethcl.ChainID(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Create transaction
+	tx := types.NewTransaction(1, common.Address{1}, big.NewInt(1), 22000, big.NewInt(1), nil)
+	signer := types.LatestSignerForChainID(chainID)
+	signature, err := crypto.Sign(signer.Hash(tx).Bytes(), testKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	signedTx, err := tx.WithSignature(signer, signature)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Send transaction
+	err = ethcl.SendTransaction(context.Background(), signedTx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Check that the transaction was send over the channel
+	tx = <-ch
+	if tx.Hash() != signedTx.Hash() {
+		t.Fatalf("Invalid tx hash received, got %v, want %v", tx.Hash(), signedTx.Hash())
+	}
+}
+
 func testCallContract(t *testing.T, client *rpc.Client) {
 	ec := New(client)
 	msg := ethereum.CallMsg{