eth/fetcher: remove dangling peers from alternates

eth/fetcher/tx_fetcher.go

@@ -816,6 +816,10 @@ func (f *TxFetcher) loop() {
 					if len(f.announced[hash]) == 0 {
 						delete(f.announced, hash)
 					}
+					delete(f.alternates[hash], drop.peer)
+					if len(f.alternates[hash]) == 0 {
+						delete(f.alternates, hash)
+					}
 				}
 				delete(f.announces, drop.peer)
 			}
@@ -879,7 +883,7 @@ func (f *TxFetcher) rescheduleWait(timer *mclock.Timer, trigger chan struct{}) {
 // This method is a bit "flaky" "by design". In theory the timeout timer only ever
 // should be rescheduled if some request is pending. In practice, a timeout will
 // cause the timer to be rescheduled every 5 secs (until the peer comes through or
-// disconnects). This is a limitation of the fetcher code because we don't trac
+// disconnects). This is a limitation of the fetcher code because we don't track
 // pending requests and timed out requests separately. Without double tracking, if
 // we simply didn't reschedule the timer on all-timeout then the timer would never
 // be set again since len(request) > 0 => something's running.

eth/fetcher/tx_fetcher_test.go

@@ -1858,6 +1858,56 @@ func TestBlobTransactionAnnounce(t *testing.T) {
 	})
 }
 
+func TestTransactionFetcherDropAlternates(t *testing.T) {
+	testTransactionFetcherParallel(t, txFetcherTest{
+		init: func() *TxFetcher {
+			return NewTxFetcher(
+				func(common.Hash) bool { return false },
+				func(txs []*types.Transaction) []error {
+					return make([]error, len(txs))
+				},
+				func(string, []common.Hash) error { return nil },
+				nil,
+			)
+		},
+		steps: []interface{}{
+			doTxNotify{peer: "A", hashes: []common.Hash{testTxsHashes[0]}, types: []byte{testTxs[0].Type()}, sizes: []uint32{uint32(testTxs[0].Size())}},
+			doWait{time: txArriveTimeout, step: true},
+			doTxNotify{peer: "B", hashes: []common.Hash{testTxsHashes[0]}, types: []byte{testTxs[0].Type()}, sizes: []uint32{uint32(testTxs[0].Size())}},
+
+			isScheduled{
+				tracking: map[string][]announce{
+					"A": {
+						{testTxsHashes[0], testTxs[0].Type(), uint32(testTxs[0].Size())},
+					},
+					"B": {
+						{testTxsHashes[0], testTxs[0].Type(), uint32(testTxs[0].Size())},
+					},
+				},
+				fetching: map[string][]common.Hash{
+					"A": {testTxsHashes[0]},
+				},
+			},
+			doDrop("B"),
+
+			isScheduled{
+				tracking: map[string][]announce{
+					"A": {
+						{testTxsHashes[0], testTxs[0].Type(), uint32(testTxs[0].Size())},
+					},
+				},
+				fetching: map[string][]common.Hash{
+					"A": {testTxsHashes[0]},
+				},
+			},
+			doDrop("A"),
+			isScheduled{
+				tracking: nil, fetching: nil,
+			},
+		},
+	})
+}
+
 func testTransactionFetcherParallel(t *testing.T, tt txFetcherTest) {
 	t.Parallel()
 	testTransactionFetcher(t, tt)