From 91967cbd407254358ab768e74ebcfda8d4a30bc8 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Fri, 22 Nov 2024 10:32:53 -0500
Subject: reliable unicast pseudocode

---
 doc/runicast.pseudo | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 doc/runicast.pseudo

(limited to 'doc/runicast.pseudo')

diff --git a/doc/runicast.pseudo b/doc/runicast.pseudo
new file mode 100644
index 0000000..1721025
--- /dev/null
+++ b/doc/runicast.pseudo
@@ -0,0 +1,67 @@
+type Message[T] struct {
+	seq int
+	data T
+}
+
+type Ack int
+
+class sender[T] {
+	const ackTimeout = 500ms
+
+	var (
+		next := 0 // Next sequence number.
+		unacked := 0 // Sequence number of first unacked message.
+		sent Queue[Message[T]]
+		sock Socket
+	)
+
+	func send(data) {
+		msg := Message{next, data}
+		sock.send(msg)
+		sent.add(msg)
+		next++
+	}
+
+	thread retransmit() {
+		wait(ackTimeout)
+
+		if unacked < next {
+			forall msg in sent s.t. msg.seq >= unacked {
+				sock.send(msg)
+			}
+		}
+	}
+
+	thread recvAcks() {
+		ack := sock.receive()
+
+		if ack >= unacked {
+			unacked = ack+1
+		}
+
+		while sent.peek().seq <= ack {
+			sent.pop()
+		}
+	}
+}
+
+class receiver[T] {
+	var (
+		seq := 0 // Next sequence number.
+		sock Socket
+		delivered Queue[T]
+	)
+
+	thread recv() {
+		msg := sock.receive()
+		if msg.seq == seq {
+			delivered.add(msg.data)
+			sock.send(Ack(seq))
+			seq++
+		}
+	}
+
+	func deliver() T {
+		return delivered.pop()
+	}
+}
-- 
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