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>

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{