From c380ec810fe8a23d7d10114f4aaf03ffe7679dbc Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Sat, 16 Nov 2024 12:35:48 -0500
Subject: reliable multicast: add nonblocking receive methods

---
 .../derms/net/rmulticast/ReliableMulticast.java    | 23 ++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/main/java/derms/net/rmulticast/ReliableMulticast.java b/src/main/java/derms/net/rmulticast/ReliableMulticast.java
index 72b3019..039e790 100644
--- a/src/main/java/derms/net/rmulticast/ReliableMulticast.java
+++ b/src/main/java/derms/net/rmulticast/ReliableMulticast.java
@@ -5,10 +5,12 @@ import derms.net.Packet;
 
 import java.io.IOException;
 import java.net.*;
+import java.time.Duration;
 import java.util.Set;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
 
 /**
@@ -86,4 +88,25 @@ public class ReliableMulticast<T extends MessagePayload> {
         Message<T> msg = delivered.take(); // Blocks until a message becomes available.
         return msg.payload;
     }
+
+    /** Receive a message, or return null if none are available. */
+    public T tryReceive() {
+        Message<T> msg = delivered.poll();
+        if (msg == null)
+            return null;
+        return msg.payload;
+    }
+
+    /**
+     * Receive a message, waiting up to the specified wait time if necessary.
+     *
+     * @return A message received from the group, or null if the specified waiting
+     * time elapses before a message arrives.
+     */
+    public T tryReceive(Duration waitTime) throws InterruptedException {
+        Message<T> msg = delivered.poll(waitTime.toMillis(), TimeUnit.MILLISECONDS);
+        if (msg == null)
+            return null;
+        return msg.payload;
+    }
 }
-- 
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