From 9484ecbfbc588efe7135b2656999a82fb1f31818 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Wed, 14 May 2014 17:13:02 -0400
Subject: [PATCH] Noddy pingpong tests of erlang and plain racket thread IPC

---
 pingpong.erl | 41 +++++++++++++++++++++++++++++++++++++++++
 pingpong.rkt | 24 ++++++++++++++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 pingpong.erl
 create mode 100644 pingpong.rkt

diff --git a/pingpong.erl b/pingpong.erl
new file mode 100644
index 0000000..bb88459
--- /dev/null
+++ b/pingpong.erl
@@ -0,0 +1,41 @@
+-module(pingpong).
+-export([oneway/0, consumer/0, pingpong/0]).
+
+oneway() ->
+    N = 10000000,
+    Pid = spawn(?MODULE, consumer, []),
+    Start = erlang:now(),
+    dotimes(N - 1, fun () -> Pid ! message end),
+    Pid ! {done, self()},
+    receive ok -> ok end,
+    Stop = erlang:now(),
+    N / time_diff(Start, Stop).
+
+pingpong() ->
+    N = 10000000,
+    Pid = spawn(?MODULE, consumer, []),
+    Start = erlang:now(),
+    Message = {ping, self()},
+    dotimes(N, fun () ->
+                       Pid ! Message,
+                       receive pong -> ok end
+               end),
+    Stop = erlang:now(),
+    N / time_diff(Start, Stop).
+
+consumer() ->
+    receive
+        message -> consumer();
+        {done, Pid} -> Pid ! ok;
+        {ping, Pid} ->
+            Pid ! pong,
+            consumer()
+    end.
+
+dotimes(0, _) -> done;
+dotimes(N, F) ->
+    F(),
+    dotimes(N - 1, F).
+
+time_diff({A1,A2,A3}, {B1,B2,B3}) ->
+    (B1 - A1) * 1000000 + (B2 - A2) + (B3 - A3) / 1000000.0 .
diff --git a/pingpong.rkt b/pingpong.rkt
new file mode 100644
index 0000000..40d02a3
--- /dev/null
+++ b/pingpong.rkt
@@ -0,0 +1,24 @@
+#lang racket
+
+(define echoer
+  (thread
+   (lambda ()
+     (let loop ()
+       (define source (thread-receive))
+       (thread-send source #t)
+       (loop)))))
+
+(define LIMIT 10000000)
+(define start-time (current-inexact-milliseconds))
+(let loop ((n 0))
+  (when (< n LIMIT)
+    (thread-send echoer (current-thread))
+    (thread-receive)
+    (loop (+ n 1))))
+(define stop-time (current-inexact-milliseconds))
+(define deltasec (/ (- stop-time start-time) 1000.0))
+(define roundtrip-hz (/ LIMIT deltasec))
+(printf "~v roundtrips/sec, i.e. ~v messages/sec\n"
+	roundtrip-hz
+	(* 2 roundtrip-hz))
+(printf "That's a per-message latency of ~v\n" (/ (* 2 roundtrip-hz)))