From 05c4e2b5770133228daff7c262945f078a4e4456 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Sat, 16 Nov 2024 14:28:13 -0500
Subject: ReliableMulticast.close()

---
 .../derms/net/rmulticast/ReliableMulticast.java    | 36 +++++++++++++---------
 1 file changed, 21 insertions(+), 15 deletions(-)

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

diff --git a/src/main/java/derms/net/rmulticast/ReliableMulticast.java b/src/main/java/derms/net/rmulticast/ReliableMulticast.java
index dd2991a..6edab5d 100644
--- a/src/main/java/derms/net/rmulticast/ReliableMulticast.java
+++ b/src/main/java/derms/net/rmulticast/ReliableMulticast.java
@@ -7,10 +7,7 @@ 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.concurrent.*;
 import java.util.logging.Logger;
 
 /**
@@ -20,6 +17,8 @@ import java.util.logging.Logger;
  * Distributed Systems" in IEEE Transactions on Parallel and Distributed Systems, vol. 1, no. 1, 1990.
  */
 public class ReliableMulticast<T extends MessagePayload> {
+    private static final Duration terminationTimeout = Duration.ofSeconds(1);
+
     private final SocketAddress group;
     private final InetAddress laddr; // Local address.
     private final Set<MessageID> acks; // Positively acknowledged messages.
@@ -30,6 +29,7 @@ public class ReliableMulticast<T extends MessagePayload> {
     private final ConcurrentMulticastSocket outSock;
     private final BlockingQueue<Message<T>> delivered;
     private final Logger log;
+    private final ExecutorService pool;
 
     /**
      * Join the specified multicast group.
@@ -54,20 +54,26 @@ public class ReliableMulticast<T extends MessagePayload> {
 
         this.log = Logger.getLogger(this.getClass().getName());
 
-        ConcurrentMulticastSocket inSock = new ConcurrentMulticastSocket(group.getPort());
-        inSock.joinGroup(group.getAddress());
-        (new Thread(new Receive<T>(inSock, acks, nacks, received, retransmissions, groupMembers, delivered))).start();
-
-        (new Thread(new Retransmit<T>(retransmissions, outSock, group))).start();
-
-        (new Thread(new Prune<T>(received, groupMembers))).start();
+        this.pool = Executors.newCachedThreadPool();
+        pool.execute(new Receive<T>(group, acks, nacks, received, retransmissions, groupMembers, delivered));
+        pool.execute(new Retransmit<T>(retransmissions, outSock, group));
+        pool.execute(new Prune<T>(received, groupMembers));
+        pool.execute(new Heartbeat(group, laddr, acks, nacks, outSock));
+    }
 
+    public void close() {
+        log.info("Shutting down...");
+        pool.shutdownNow();
         try {
-            (new Thread(new Heartbeat(group, laddr, acks, nacks, outSock))).start();
-        } catch (IOException e) {
-            log.severe("Failed to start heartbeat thread: " + e.getMessage());
-            throw e;
+            if (!pool.awaitTermination(terminationTimeout.toMillis(), TimeUnit.MILLISECONDS))
+                log.warning("Thread pool did not terminate after " + terminationTimeout);
+        } catch (InterruptedException e) {
+            log.warning("Interrupted while terminating thread pool: " + e.getMessage());
+            // Preserve interrupt status.
+            Thread.currentThread().interrupt();
         }
+        outSock.close();
+        log.info("Finished shutting down.");
     }
 
     /** Send a message to the group. */
-- 
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