From 6bd335c7382c0da8486e94d253dffa28525ceec7 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Mon, 18 Nov 2024 10:35:22 -0500
Subject: reliable multicast: avoid receiving duplicate messages

---
 src/main/java/derms/net/rmulticast/Receive.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src/main/java/derms/net/rmulticast/Receive.java')

diff --git a/src/main/java/derms/net/rmulticast/Receive.java b/src/main/java/derms/net/rmulticast/Receive.java
index bf583dd..679df27 100644
--- a/src/main/java/derms/net/rmulticast/Receive.java
+++ b/src/main/java/derms/net/rmulticast/Receive.java
@@ -95,8 +95,8 @@ class Receive<T extends MessagePayload> implements Runnable {
     private void deliver(Message<T> msg) {
         acks.add(msg.id());
         nacks.remove(msg.id());
-        received.add(msg);
         retransmissions.remove(msg);
-        delivered.add(msg);
+        if (received.add(msg))
+            delivered.add(msg); // First time seeing this message; deliver it.
     }
 }
-- 
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