From 3ebcee7b335d0e23915f3ec8e15c9995cd8d3004 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Fri, 15 Nov 2024 11:39:46 -0500
Subject: reliable multicast: Receive

---
 src/main/java/derms/net/rmulticast/Receive.java    | 68 ++++++++++++++++++++++
 .../java/derms/net/rmulticast/ReceivedSet.java     | 25 ++++++++
 .../derms/net/rmulticast/ReliableMulticast.java    | 14 +----
 3 files changed, 96 insertions(+), 11 deletions(-)
 create mode 100644 src/main/java/derms/net/rmulticast/Receive.java
 create mode 100644 src/main/java/derms/net/rmulticast/ReceivedSet.java

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

diff --git a/src/main/java/derms/net/rmulticast/Receive.java b/src/main/java/derms/net/rmulticast/Receive.java
new file mode 100644
index 0000000..c8467c2
--- /dev/null
+++ b/src/main/java/derms/net/rmulticast/Receive.java
@@ -0,0 +1,68 @@
+package derms.net.rmulticast;
+
+import derms.net.ConcurrentMulticastSocket;
+import derms.net.Packet;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.net.DatagramPacket;
+import java.util.Set;
+import java.util.concurrent.BlockingQueue;
+import java.util.logging.Logger;
+
+class Receive<T extends Serializable & Hashable> implements Runnable {
+    private static final int bufSize = 8192;
+
+    private final ConcurrentMulticastSocket inSock;
+    private final Set<MessageID> positiveAcks;
+    private final Set<MessageID> negativeAcks;
+    private final ReceivedSet<T> received;
+    private final BlockingQueue<Message<T>> retransmissions;
+    private final Logger log;
+
+    Receive(ConcurrentMulticastSocket inSock, Set<MessageID> positiveAcks, Set<MessageID> negativeAcks, ReceivedSet<T> received, BlockingQueue<Message<T>> retransmissions) {
+        this.inSock = inSock;
+        this.positiveAcks = positiveAcks;
+        this.negativeAcks = negativeAcks;
+        this.received = received;
+        this.retransmissions = retransmissions;
+        this.log = Logger.getLogger(this.getClass().getName());
+    }
+
+    @Override
+    public void run() {
+        DatagramPacket pkt = new DatagramPacket(new byte[bufSize], bufSize);
+        Message<T> msg;
+        for (;;) {
+            try {
+                inSock.receive(pkt);
+                msg = Packet.decode(pkt, Message.class);
+                receive(msg);
+            } catch (IOException | ClassNotFoundException | ClassCastException e) {
+                log.warning(e.getMessage());
+            }
+        }
+    }
+
+    private void receive(Message<T> msg) {
+        positiveAcks.add(msg.id());
+        received.add(msg);
+
+        negativeAcks.remove(msg.id());
+        retransmissions.remove(msg);
+
+        for (MessageID mid : msg.positiveAcks) {
+            positiveAcks.remove(mid);
+            if (!received.contains(mid))
+                negativeAcks.add(mid);
+        }
+
+        for (MessageID mid : msg.negativeAcks) {
+            if (received.contains(mid)) {
+                retransmissions.add(msg);
+            } else {
+                negativeAcks.add(mid);
+            }
+        }
+    }
+}
diff --git a/src/main/java/derms/net/rmulticast/ReceivedSet.java b/src/main/java/derms/net/rmulticast/ReceivedSet.java
new file mode 100644
index 0000000..339a714
--- /dev/null
+++ b/src/main/java/derms/net/rmulticast/ReceivedSet.java
@@ -0,0 +1,25 @@
+package derms.net.rmulticast;
+
+import java.io.Serializable;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+class ReceivedSet<T extends Serializable & Hashable> {
+    private final Set<Message<T>> received;
+
+    ReceivedSet() {
+        this.received = new ConcurrentHashMap<Message<T>, Void>().keySet();
+    }
+
+    void add(Message<T> e) {
+        received.add(e);
+    }
+
+    // TODO: faster search.
+    boolean contains(MessageID mid) {
+        for (Message<T> msg : received)
+            if (msg.id().equals(mid))
+                return true;
+        return false;
+    }
+}
diff --git a/src/main/java/derms/net/rmulticast/ReliableMulticast.java b/src/main/java/derms/net/rmulticast/ReliableMulticast.java
index 85d4f31..44fc10c 100644
--- a/src/main/java/derms/net/rmulticast/ReliableMulticast.java
+++ b/src/main/java/derms/net/rmulticast/ReliableMulticast.java
@@ -18,7 +18,7 @@ import java.util.logging.Logger;
 public class ReliableMulticast<T extends Serializable & Hashable> {
     private final Set<MessageID> positiveAcks; // Positively acknowledged messages.
     private final Set<MessageID> negativeAcks; // Negatively acknowledged messages.
-    private final Set<Message<T>> received;
+    private final ReceivedSet<T> received;
     private final BlockingQueue<Message<T>> retransmissions; // Messages pending retransmission.
     private final AtomicReference<Instant> lastSend;
     private final SocketAddress group;
@@ -30,7 +30,7 @@ public class ReliableMulticast<T extends Serializable & Hashable> {
     public ReliableMulticast(InetSocketAddress group, InetAddress laddr) throws IOException {
         this.positiveAcks = new ConcurrentHashMap<MessageID, Void>().keySet();
         this.negativeAcks = new ConcurrentHashMap<MessageID, Void>().keySet();
-        this.received = new ConcurrentHashMap<Message<T>, Void>().keySet();
+        this.received = new ReceivedSet<T>();
         this.retransmissions = new LinkedBlockingQueue<Message<T>>();
         this.lastSend = new AtomicReference<Instant>(Instant.now());
 
@@ -48,7 +48,7 @@ public class ReliableMulticast<T extends Serializable & Hashable> {
 
         this.log = Logger.getLogger(this.getClass().getName());
 
-        (new Thread(new Receive())).start();
+        (new Thread(new Receive<T>(inSock, positiveAcks, negativeAcks, received, retransmissions))).start();
         (new Thread(new Retransmit<T>(retransmissions, outSock, group))).start();
     }
 
@@ -64,12 +64,4 @@ public class ReliableMulticast<T extends Serializable & Hashable> {
         (new Thread(new Timeout<T>(msg, positiveAcks, retransmissions))).start();
         lastSend.set(Instant.now());
     }
-
-    private class Receive implements Runnable {
-        @Override
-        public void run() {
-            // TODO
-        }
-    }
-
 }
-- 
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