From ba69c1ff291c1daface52bb01bf6307ffb6c822d Mon Sep 17 00:00:00 2001
From: Kim De Mey <kim.demey@gmail.com>
Date: Thu, 6 Oct 2022 13:34:35 +0200
Subject: [PATCH] Quickfix for a potential double future completion in rlpx
 (#538)

---
 eth/p2p/rlpx.nim | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/eth/p2p/rlpx.nim b/eth/p2p/rlpx.nim
index a69d06c..fc3b916 100644
--- a/eth/p2p/rlpx.nim
+++ b/eth/p2p/rlpx.nim
@@ -148,8 +148,10 @@ proc requestResolver[MsgType](msg: pointer, future: FutureBase) {.gcsafe.} =
 
 proc linkSendFailureToReqFuture[S, R](sendFut: Future[S], resFut: Future[R]) =
   sendFut.addCallback() do (arg: pointer):
-    if not sendFut.error.isNil:
-      resFut.fail(sendFut.error)
+    # Avoiding potentially double future completions
+    if not resFut.finished:
+      if sendFut.failed:
+        resFut.fail(sendFut.error)
 
 proc messagePrinter[MsgType](msg: pointer): string {.gcsafe.} =
   result = ""