From 19fcec84d8d7d21e796c7624e521b60d28ee21ed Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 7 Apr 2024 20:45:59 +0200
Subject: Adding upstream version 16.2.11+ds.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 src/seastar/demos/udp_zero_copy_demo.cc | 153 ++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 src/seastar/demos/udp_zero_copy_demo.cc

(limited to 'src/seastar/demos/udp_zero_copy_demo.cc')

diff --git a/src/seastar/demos/udp_zero_copy_demo.cc b/src/seastar/demos/udp_zero_copy_demo.cc
new file mode 100644
index 000000000..a0d7733a3
--- /dev/null
+++ b/src/seastar/demos/udp_zero_copy_demo.cc
@@ -0,0 +1,153 @@
+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  You may not use this file except in compliance with the License.
+ *
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*
+ * Copyright (C) 2014 Cloudius Systems, Ltd.
+ */
+
+#include <seastar/core/seastar.hh>
+#include <seastar/core/app-template.hh>
+#include <seastar/core/scattered_message.hh>
+#include <seastar/core/vector-data-sink.hh>
+#include <seastar/core/shared_ptr.hh>
+#include <seastar/core/units.hh>
+#include <seastar/core/timer.hh>
+#include <seastar/net/api.hh>
+#include <random>
+#include <iomanip>
+#include <iostream>
+
+using namespace seastar;
+using namespace net;
+using namespace std::chrono_literals;
+namespace bpo = boost::program_options;
+
+template <typename Duration>
+typename Duration::rep to_seconds(Duration d) {
+    return std::chrono::duration_cast<std::chrono::seconds>(d).count();
+}
+
+class server {
+private:
+    udp_channel _chan;
+    timer<> _stats_timer;
+    uint64_t _n_sent {};
+    size_t _chunk_size;
+    bool _copy;
+    std::vector<packet> _packets;
+    std::unique_ptr<output_stream<char>> _out;
+    steady_clock_type::time_point _last;
+    sstring _key;
+    size_t _packet_size = 8*KB;
+    char* _mem;
+    size_t _mem_size;
+    std::mt19937 _rnd;
+    std::random_device _randem_dev;
+    std::uniform_int_distribution<size_t> _chunk_distribution;
+private:
+    char* next_chunk() {
+        return _mem + _chunk_distribution(_rnd);
+    }
+public:
+    server()
+        : _rnd(std::random_device()()) {
+    }
+    future<> send(ipv4_addr dst, packet p) {
+        return _chan.send(dst, std::move(p)).then([this] {
+            _n_sent++;
+        });
+    }
+    void start(int chunk_size, bool copy, size_t mem_size) {
+        ipv4_addr listen_addr{10000};
+        _chan = make_udp_channel(listen_addr);
+
+        std::cout << "Listening on " << listen_addr << std::endl;
+
+        _last = steady_clock_type::now();
+        _stats_timer.set_callback([this] {
+            auto now = steady_clock_type::now();
+            std::cout << "Out: "
+                << std::setprecision(2) << std::fixed
+                << (double)_n_sent / to_seconds(now - _last)
+                << " pps" << std::endl;
+            _last = now;
+            _n_sent = 0;
+        });
+        _stats_timer.arm_periodic(1s);
+
+        _chunk_size = chunk_size;
+        _copy = copy;
+        _key = sstring(new char[64], 64);
+
+        _out = std::make_unique<output_stream<char>>(
+            data_sink(std::make_unique<vector_data_sink>(_packets)), _packet_size);
+
+        _mem = new char[mem_size];
+        _mem_size = mem_size;
+
+        _chunk_distribution = std::uniform_int_distribution<size_t>(0, _mem_size - _chunk_size * 3);
+
+        assert(3 * _chunk_size <= _packet_size);
+
+        // Run sender in background.
+        (void)keep_doing([this] {
+            return _chan.receive().then([this] (udp_datagram dgram) {
+                auto chunk = next_chunk();
+                lw_shared_ptr<sstring> item;
+                if (_copy) {
+                    _packets.clear();
+                    // FIXME: future is discarded
+                    (void)_out->write(chunk, _chunk_size);
+                    chunk += _chunk_size;
+                    (void)_out->write(chunk, _chunk_size);
+                    chunk += _chunk_size;
+                    (void)_out->write(chunk, _chunk_size);
+                    (void)_out->flush();
+                    assert(_packets.size() == 1);
+                    return send(dgram.get_src(), std::move(_packets[0]));
+                } else {
+                    auto chunk = next_chunk();
+                    scattered_message<char> msg;
+                    msg.reserve(3);
+                    msg.append_static(chunk, _chunk_size);
+                    msg.append_static(chunk, _chunk_size);
+                    msg.append_static(chunk, _chunk_size);
+                    return send(dgram.get_src(), std::move(msg).release());
+                }
+            });
+        });
+    }
+};
+
+int main(int ac, char ** av) {
+    server s;
+    app_template app;
+    app.add_options()
+        ("chunk-size", bpo::value<int>()->default_value(1024),
+             "Chunk size")
+        ("mem-size", bpo::value<int>()->default_value(512),
+             "Memory pool size in MiB")
+        ("copy", "Copy data rather than send via zero-copy")
+        ;
+    return app.run_deprecated(ac, av, [&app, &s] {
+        auto&& config = app.configuration();
+        auto chunk_size = config["chunk-size"].as<int>();
+        auto mem_size = (size_t)config["mem-size"].as<int>() * MB;
+        auto copy = config.count("copy");
+        s.start(chunk_size, copy, mem_size);
+    });
+}
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