Optimize handling of non-existing transactions in the Electrum client

pkg/bitcoin/electrum/electrum.go

@@ -88,7 +88,18 @@ func (c *Connection) GetTransaction(
 			// We cannot use `GetTransaction` to get the the transaction details
 			// as Esplora/Electrs doesn't support verbose transactions.
 			// See: https://github.com/Blockstream/electrs/pull/36
-			return client.GetRawTransaction(ctx, txID)
+			tx, err := client.GetRawTransaction(ctx, txID)
+			if err != nil {
+				if isTxNotFoundErr(err) {
+					// The transaction was not found on the chain. There is
+					// no point in retrying the request and losing time.
+					return "", nil
+				}
+
+				return "", err
+			}
+
+			return tx, nil
 		},
 		"GetRawTransaction",
 	)
@@ -99,6 +110,13 @@ func (c *Connection) GetTransaction(
 			err,
 		)
 	}
+	if len(rawTransaction) == 0 {
+		return nil, fmt.Errorf(
+			"failed to get raw transaction with ID [%s]: [%v]",
+			txID,
+			fmt.Errorf("not found"),
+		)
+	}
 
 	result, err := convertRawTransaction(rawTransaction)
 	if err != nil {
@@ -123,10 +141,21 @@ func (c *Connection) GetTransactionConfirmations(
 	rawTransaction, err := requestWithRetry(
 		c,
 		func(ctx context.Context, client *electrum.Client) (string, error) {
-			// We cannot use `GetTransaction` to get the the transaction details
+			// We cannot use `GetTransaction` to get the transaction details
 			// as Esplora/Electrs doesn't support verbose transactions.
 			// See: https://github.com/Blockstream/electrs/pull/36
-			return client.GetRawTransaction(ctx, txID)
+			tx, err := client.GetRawTransaction(ctx, txID)
+			if err != nil {
+				if isTxNotFoundErr(err) {
+					// The transaction was not found on the chain. There is
+					// no point in retrying the request and losing time.
+					return "", nil
+				}
+
+				return "", err
+			}
+
+			return tx, nil
 		},
 		"GetRawTransaction",
 	)
@@ -138,6 +167,13 @@ func (c *Connection) GetTransactionConfirmations(
 				err,
 			)
 	}
+	if len(rawTransaction) == 0 {
+		return 0, fmt.Errorf(
+			"failed to get raw transaction with ID [%s]: [%v]",
+			txID,
+			fmt.Errorf("not found"),
+		)
+	}
 
 	tx, err := decodeTransaction(rawTransaction)
 	if err != nil {
@@ -224,6 +260,24 @@ txOutLoop:
 	return 0, nil
 }
 
+func isTxNotFoundErr(err error) bool {
+	txNotFoundErrs := []string{
+		"no such mempool or blockchain transaction",
+		"missing transaction",
+		"transaction not found",
+	}
+
+	errStr := strings.ToLower(err.Error())
+
+	for _, txNotFoundErr := range txNotFoundErrs {
+		if strings.Contains(errStr, txNotFoundErr) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // BroadcastTransaction broadcasts the given transaction over the
 // network of the Bitcoin chain nodes. If the broadcast action could not be
 // done, this function returns an error. This function does not give any

pkg/bitcoin/electrum/electrum_integration_test.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"math"
+	"reflect"
 	"sort"
 	"strings"
 	"testing"
@@ -175,15 +176,19 @@ func TestGetTransaction_Negative_Integration(t *testing.T) {
 
 		_, err := electrum.GetTransaction(invalidTxID)
 
-		assertMissingTransactionError(
-			t,
-			testConfig.clientConfig,
-			fmt.Sprintf(
-				"failed to get raw transaction with ID [%s]",
-				invalidTxID.Hex(bitcoin.ReversedByteOrder),
-			),
-			err,
+		expectedErr := fmt.Errorf(
+			"failed to get raw transaction with ID [%s]: [not found]",
+			invalidTxID.Hex(bitcoin.ReversedByteOrder),
 		)
+		if !reflect.DeepEqual(expectedErr, err) {
+			t.Errorf(
+				"unexpected error\n"+
+					"expected: %v\n"+
+					"actual:   %v\n",
+				expectedErr,
+				err,
+			)
+		}
 	})
 }
 
@@ -221,15 +226,19 @@ func TestGetTransactionConfirmations_Negative_Integration(t *testing.T) {
 
 		_, err := electrum.GetTransactionConfirmations(invalidTxID)
 
-		assertMissingTransactionError(
-			t,
-			testConfig.clientConfig,
-			fmt.Sprintf(
-				"failed to get raw transaction with ID [%s]",
-				invalidTxID.Hex(bitcoin.ReversedByteOrder),
-			),
-			err,
+		expectedErr := fmt.Errorf(
+			"failed to get raw transaction with ID [%s]: [not found]",
+			invalidTxID.Hex(bitcoin.ReversedByteOrder),
 		)
+		if !reflect.DeepEqual(expectedErr, err) {
+			t.Errorf(
+				"unexpected error\n"+
+					"expected: %v\n"+
+					"actual:   %v\n",
+				expectedErr,
+				err,
+			)
+		}
 	})
 }
 
@@ -607,17 +616,11 @@ func assertNumberCloseTo(t *testing.T, expected uint, actual uint, delta uint) {
 }
 
 type expectedErrorMessages struct {
-	missingTransaction        []string
 	missingBlockHeader        []string
 	missingTransactionInBlock []string
 }
 
 var expectedServerErrorMessages = expectedErrorMessages{
-	missingTransaction: []string{
-		"errNo: 0, errMsg: missing transaction",
-		"errNo: 2, errMsg: daemon error: DaemonError({'code': -5, 'message': 'No such mempool or blockchain transaction. Use gettransaction for wallet transactions.'})",
-		"errNo: 2, errMsg: daemon error: DaemonError({'message': 'Transaction not found.', 'code': -1})",
-	},
 	missingBlockHeader: []string{
 		"errNo: 0, errMsg: missing header",
 		"errNo: 1, errMsg: height 4,294,967,295 out of range",
@@ -629,22 +632,6 @@ var expectedServerErrorMessages = expectedErrorMessages{
 		"errNo: 1, errMsg: No transaction matching the requested hash found at height 123456"},
 }
 
-func assertMissingTransactionError(
-	t *testing.T,
-	clientConfig electrum.Config,
-	clientErrorPrefix string,
-
-	actualError error,
-) {
-	assertServerError(
-		t,
-		clientConfig,
-		clientErrorPrefix,
-		expectedServerErrorMessages.missingTransaction,
-		actualError,
-	)
-}
-
 func assertMissingBlockHeaderError(
 	t *testing.T,
 	clientConfig electrum.Config,