/*
 * 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) 2016 ScyllaDB
 */

#include "loopback_socket.hh"
#include "seastar/core/condition-variable.hh"
#include "seastar/core/temporary_buffer.hh"
#include <seastar/rpc/rpc.hh>
#include <seastar/rpc/rpc_types.hh>
#include <seastar/rpc/lz4_compressor.hh>
#include <seastar/rpc/lz4_fragmented_compressor.hh>
#include <seastar/rpc/multi_algo_compressor_factory.hh>
#include <seastar/testing/random.hh>
#include <seastar/testing/test_case.hh>
#include <seastar/testing/thread_test_case.hh>
#include <seastar/testing/test_runner.hh>
#include <seastar/core/thread.hh>
#include <seastar/core/sleep.hh>
#include <seastar/core/distributed.hh>
#include <seastar/core/loop.hh>
#include <seastar/core/metrics_api.hh>
#include <seastar/util/defer.hh>
#include <seastar/util/log.hh>
#include <seastar/util/closeable.hh>
#include <seastar/util/noncopyable_function.hh>
#include <seastar/util/later.hh>

#include <span>

using namespace seastar;

struct serializer {
};

template <typename T, typename Output>
inline
void write_arithmetic_type(Output& out, T v) {
    static_assert(std::is_arithmetic_v<T>, "must be arithmetic type");
    return out.write(reinterpret_cast<const char*>(&v), sizeof(T));
}

template <typename T, typename Input>
inline
T read_arithmetic_type(Input& in) {
    static_assert(std::is_arithmetic_v<T>, "must be arithmetic type");
    T v;
    in.read(reinterpret_cast<char*>(&v), sizeof(T));
    return v;
}

template <typename Output>
inline void write(serializer, Output& output, int32_t v) { return write_arithmetic_type(output, v); }
template <typename Output>
inline void write(serializer, Output& output, uint32_t v) { return write_arithmetic_type(output, v); }
template <typename Output>
inline void write(serializer, Output& output, int64_t v) { return write_arithmetic_type(output, v); }
template <typename Output>
inline void write(serializer, Output& output, uint64_t v) { return write_arithmetic_type(output, v); }
template <typename Output>
inline void write(serializer, Output& output, double v) { return write_arithmetic_type(output, v); }
template <typename Input>
inline int32_t read(serializer, Input& input, rpc::type<int32_t>) { return read_arithmetic_type<int32_t>(input); }
template <typename Input>
inline uint32_t read(serializer, Input& input, rpc::type<uint32_t>) { return read_arithmetic_type<uint32_t>(input); }
template <typename Input>
inline uint64_t read(serializer, Input& input, rpc::type<uint64_t>) { return read_arithmetic_type<uint64_t>(input); }
template <typename Input>
inline uint64_t read(serializer, Input& input, rpc::type<int64_t>) { return read_arithmetic_type<int64_t>(input); }
template <typename Input>
inline double read(serializer, Input& input, rpc::type<double>) { return read_arithmetic_type<double>(input); }

template <typename Output>
inline void write(serializer, Output& out, const sstring& v) {
    write_arithmetic_type(out, uint32_t(v.size()));
    out.write(v.c_str(), v.size());
}

template <typename Input>
inline sstring read(serializer, Input& in, rpc::type<sstring>) {
    auto size = read_arithmetic_type<uint32_t>(in);
    sstring ret = uninitialized_string(size);
    in.read(ret.data(), size);
    return ret;
}

using test_rpc_proto = rpc::protocol<serializer>;
using make_socket_fn = std::function<seastar::socket ()>;

class rpc_loopback_error_injector : public loopback_error_injector {
public:
    struct config {
        struct {
            int limit = 0;
            error kind = error::none;
        private:
            friend class rpc_loopback_error_injector;
            int _x = 0;
            error inject() {
                return _x++ >= limit ? kind : error::none;
            }
        } server_rcv = {}, server_snd = {}, client_rcv = {}, client_snd = {};
        error connect_kind = error::none;
        std::chrono::microseconds connect_delay = std::chrono::microseconds(0);
    };
private:
    config _cfg;
public:
    rpc_loopback_error_injector(config cfg) : _cfg(std::move(cfg)) {}

    error server_rcv_error() override {
        return _cfg.server_rcv.inject();
    }

    error server_snd_error() override {
        return _cfg.server_snd.inject();
    }

    error client_rcv_error() override {
        return _cfg.client_rcv.inject();
    }

    error client_snd_error() override {
        return _cfg.client_snd.inject();
    }

    error connect_error() override {
        return _cfg.connect_kind;
    }

    std::chrono::microseconds connect_delay() override {
        return _cfg.connect_delay;
    }
};

class rpc_socket_impl : public ::net::socket_impl {
    rpc_loopback_error_injector _error_injector;
    loopback_socket_impl _socket;
public:
    rpc_socket_impl(loopback_connection_factory& factory, std::optional<rpc_loopback_error_injector::config> inject_error)
            :
              _error_injector(inject_error.value_or(rpc_loopback_error_injector::config{})),
              _socket(factory, inject_error ? &_error_injector : nullptr) {
    }
    virtual future<connected_socket> connect(socket_address sa, socket_address local, transport proto = transport::TCP) override {
        return _socket.connect(sa, local, proto);
    }
    virtual void set_reuseaddr(bool reuseaddr) override {}
    virtual bool get_reuseaddr() const override { return false; };
    virtual void shutdown() override {
        _socket.shutdown();
    }
};

struct rpc_test_config {
    rpc::resource_limits resource_limits = {};
    rpc::server_options server_options = {};
    std::optional<rpc_loopback_error_injector::config> inject_error;
};

template<typename MsgType = int>
class rpc_test_env {
    struct rpc_test_service {
        test_rpc_proto _proto;
        test_rpc_proto::server _server;
        std::vector<MsgType> _handlers;

        rpc_test_service() = delete;
        explicit rpc_test_service(const rpc_test_config& cfg, loopback_connection_factory& lcf)
                : _proto(serializer())
                , _server(_proto, cfg.server_options, lcf.get_server_socket(), cfg.resource_limits)
        { }

        test_rpc_proto& proto() {
            return _proto;
        }

        test_rpc_proto::server& server() {
            return _server;
        }

        future<> stop() {
            return parallel_for_each(_handlers, [this] (auto t) {
                return proto().unregister_handler(t);
            }).finally([this] {
                return server().stop();
            });
        }

        template<typename Func>
        auto register_handler(MsgType t, scheduling_group sg, Func func) {
            _handlers.emplace_back(t);
            return proto().register_handler(t, sg, std::move(func));
        }

        future<> unregister_handler(MsgType t) {
            auto it = std::find(_handlers.begin(), _handlers.end(), t);
            assert(it != _handlers.end());
            _handlers.erase(it);
            return proto().unregister_handler(t);
        }
    };

    rpc_test_config _cfg;
    loopback_connection_factory _lcf;
    std::unique_ptr<sharded<rpc_test_service>> _service;

public:
    rpc_test_env() = delete;
    explicit rpc_test_env(rpc_test_config cfg)
        : _cfg(cfg), _service(std::make_unique<sharded<rpc_test_service>>())
    {
    }

    using test_fn = std::function<future<> (rpc_test_env<MsgType>& env)>;
    static future<> do_with(rpc_test_config cfg, test_fn&& func) {
        return seastar::do_with(rpc_test_env(cfg), [func] (rpc_test_env<MsgType>& env) {
            return env.start().then([&env, func] {
                return func(env);
            }).finally([&env] {
                return env.stop();
            });
        });
    }

    using thread_test_fn = std::function<void (rpc_test_env<MsgType>& env)>;
    static future<> do_with_thread(rpc_test_config cfg, thread_test_fn&& func) {
        return do_with(std::move(cfg), [func] (rpc_test_env<MsgType>& env) {
            return seastar::async([&env, func] {
                func(env);
            });
        });
    }

    using thread_test_fn_with_client = std::function<void (rpc_test_env<MsgType>& env, test_rpc_proto::client& cl)>;
    static future<> do_with_thread(rpc_test_config cfg, rpc::client_options co, thread_test_fn_with_client&& func) {
        return do_with(std::move(cfg), [func, co = std::move(co)] (rpc_test_env<MsgType>& env) {
            return seastar::async([&env, func, co = std::move(co)] {
                test_rpc_proto::client cl(env.proto(), co, env.make_socket(), ipv4_addr());
                auto stop = deferred_stop(cl);
                func(env, cl);
            });
        });
    }

    static future<> do_with_thread(rpc_test_config cfg, thread_test_fn_with_client&& func) {
        return do_with_thread(std::move(cfg), rpc::client_options(), std::move(func));
    }

    auto make_socket() {
        return seastar::socket(std::make_unique<rpc_socket_impl>(_lcf, _cfg.inject_error));
    };

    test_rpc_proto& proto() {
        return local_service().proto();
    }

    test_rpc_proto::server& server() {
        return local_service().server();
    }

    template<typename Func>
    future<> register_handler(MsgType t, scheduling_group sg, Func func) {
        return _service->invoke_on_all([t, func = std::move(func), sg] (rpc_test_service& s) mutable {
            s.register_handler(t, sg, std::move(func));
        });
    }

    template<typename Func>
    future<> register_handler(MsgType t, Func func) {
        return register_handler(t, scheduling_group(), std::move(func));
    }

    future<> unregister_handler(MsgType t) {
        return _service->invoke_on_all([t] (rpc_test_service& s) mutable {
            return s.unregister_handler(t);
        });
    }

private:
    rpc_test_service& local_service() {
        return _service->local();

    }

    future<> start() {
        return _service->start(std::cref(_cfg), std::ref(_lcf));
    }

    future<> stop() {
        return _service->stop().then([this] {
            return _lcf.destroy_all_shards();
        });
    }
};

struct cfactory : rpc::compressor::factory {
    mutable int use_compression = 0;
    const sstring name;
    cfactory(sstring name_ = "LZ4") : name(std::move(name_)) {}
    const sstring& supported() const override {
        return name;
    }
    class mylz4 : public rpc::lz4_compressor {
        sstring _name;
    public:
        mylz4(const sstring& n) : _name(n) {}
        sstring name() const override {
            return _name;
        }
    };
    std::unique_ptr<rpc::compressor> negotiate(sstring feature, bool is_server) const override {
        if (feature == name) {
            use_compression++;
            return std::make_unique<mylz4>(name);
        } else {
            return nullptr;
        }
    }
};

SEASTAR_TEST_CASE(test_rpc_connect) {
    std::vector<future<>> fs;

    for (auto i = 0; i < 2; i++) {
        for (auto j = 0; j < 4; j++) {
          for (bool with_delay : { true, false }) {
            auto factory = std::make_unique<cfactory>();
            rpc::server_options so;
            rpc::client_options co;
            if (i == 1) {
                so.compressor_factory = factory.get();
            }
            if (j & 1) {
                co.compressor_factory = factory.get();
            }
            co.send_timeout_data = j & 2;
            co.send_handler_duration = with_delay;
            rpc_test_config cfg;
            cfg.server_options = so;
            auto f = rpc_test_env<>::do_with_thread(cfg, co, [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
                env.register_handler(1, [](int a, int b) {
                    return make_ready_future<int>(a+b);
                }).get();
                auto sum = env.proto().make_client<int (int, int)>(1);
                auto result = sum(c1, 2, 3).get();
                BOOST_REQUIRE_EQUAL(result, 2 + 3);
            }).handle_exception([] (auto ep) {
                BOOST_FAIL("No exception expected");
            }).finally([factory = std::move(factory), i, j = j & 1] {
                if (i == 1 && j == 1) {
                    BOOST_REQUIRE_EQUAL(factory->use_compression, 2);
                } else {
                    BOOST_REQUIRE_EQUAL(factory->use_compression, 0);
                }
            });
            fs.emplace_back(std::move(f));
          }
        }
    }
    return when_all(fs.begin(), fs.end()).discard_result();
}

SEASTAR_TEST_CASE(test_rpc_connect_multi_compression_algo) {
    auto factory1 = std::make_unique<cfactory>();
    auto factory2 = std::make_unique<cfactory>("LZ4NEW");
    rpc::server_options so;
    rpc::client_options co;
    static rpc::multi_algo_compressor_factory server({factory1.get(), factory2.get()});
    static rpc::multi_algo_compressor_factory client({factory2.get(), factory1.get()});
    so.compressor_factory = &server;
    co.compressor_factory = &client;
    rpc_test_config cfg;
    cfg.server_options = so;
    return rpc_test_env<>::do_with_thread(cfg, co, [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        env.register_handler(1, [](int a, int b) {
            return make_ready_future<int>(a+b);
        }).get();
        auto sum = env.proto().make_client<int (int, int)>(1);
        auto result = sum(c1, 2, 3).get();
        BOOST_REQUIRE_EQUAL(result, 2 + 3);
    }).finally([factory1 = std::move(factory1), factory2 = std::move(factory2)] {
        BOOST_REQUIRE_EQUAL(factory1->use_compression, 0);
        BOOST_REQUIRE_EQUAL(factory2->use_compression, 2);
    });
}

SEASTAR_TEST_CASE(test_rpc_connect_abort) {
    rpc_test_config cfg;
    rpc_loopback_error_injector::config ecfg;
    ecfg.connect_kind = loopback_error_injector::error::abort;
    cfg.inject_error = ecfg;
    return rpc_test_env<>::do_with_thread(cfg, [] (rpc_test_env<>& env) {
        test_rpc_proto::client c1(env.proto(), {}, env.make_socket(), ipv4_addr());
        env.register_handler(1, []() { return make_ready_future<>(); }).get();
        auto f = env.proto().make_client<void ()>(1);
        auto fut = f(c1);
        c1.stop().get();
        try {
            fut.get();
            BOOST_REQUIRE(false);
        } catch (...) {}
        try {
            f(c1).get();
            BOOST_REQUIRE(false);
        } catch (...) {}
    });
}

SEASTAR_TEST_CASE(test_rpc_cancel) {
    using namespace std::chrono_literals;
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        bool rpc_executed = false;
        int good = 0;
        promise<> handler_called;
        future<> f_handler_called = handler_called.get_future();
        env.register_handler(1, [&rpc_executed, &handler_called] {
            handler_called.set_value(); rpc_executed = true; return sleep(1ms);
        }).get();
        auto call = env.proto().make_client<void ()>(1);
        promise<> cont;
        rpc::cancellable cancel;
        c1.suspend_for_testing(cont);
        auto f = call(c1, cancel);
        // cancel send side
        cancel.cancel();
        cont.set_value();
        try {
            f.get();
        } catch(rpc::canceled_error&) {
            good += !rpc_executed;
        };
        f = call(c1, cancel);
        // cancel wait side
        f_handler_called.then([&cancel] {
            cancel.cancel();
        }).get();
        try {
            f.get();
        } catch(rpc::canceled_error&) {
            good += 10*rpc_executed;
        };
        BOOST_REQUIRE_EQUAL(good, 11);
    });
}

SEASTAR_TEST_CASE(test_message_to_big) {
    rpc_test_config cfg;
    cfg.resource_limits = {0, 1, 100};
    return rpc_test_env<>::do_with_thread(cfg, [] (rpc_test_env<>& env, test_rpc_proto::client& c) {
        bool good = true;
        env.register_handler(1, [&] (sstring payload) mutable {
            good = false;
        }).get();
        auto call = env.proto().make_client<void (sstring)>(1);
        try {
            call(c, uninitialized_string(101)).get();
            good = false;
        } catch(std::runtime_error& err) {
        } catch(...) {
            good = false;
        }
        BOOST_REQUIRE_EQUAL(good, true);
    });
}

SEASTAR_TEST_CASE(test_rpc_remote_verb_error) {
    rpc_test_config cfg;
    return rpc_test_env<>::do_with_thread(cfg, [] (rpc_test_env<>& env) {
        test_rpc_proto::client c1(env.proto(), {}, env.make_socket(), ipv4_addr());
        env.register_handler(1, []() { throw std::runtime_error("error"); }).get();
        auto f = env.proto().make_client<void ()>(1);
        BOOST_REQUIRE_THROW(f(c1).get(), rpc::remote_verb_error);
        c1.stop().get();
    });
}

struct stream_test_result {
    bool client_source_closed = false;
    bool server_source_closed = false;
    bool sink_exception = false;
    bool sink_close_exception = false;
    bool source_done_exception = false;
    bool server_done_exception = false;
    bool client_stop_exception = false;
    bool server_stop_exception = false;
    int server_sum = 0;
    bool exception_while_creating_sink = false;
};

future<stream_test_result> stream_test_func(rpc_test_env<>& env, bool stop_client, bool stop_server, bool expect_connection_error = false) {
    return seastar::async([&env, stop_client, stop_server, expect_connection_error] {
        stream_test_result r;
        test_rpc_proto::client c(env.proto(), {}, env.make_socket(), ipv4_addr());
        future<> server_done = make_ready_future();
        env.register_handler(1, [&](int i, rpc::source<int> source) {
            BOOST_REQUIRE_EQUAL(i, 666);
            auto sink = source.make_sink<serializer, sstring>();
            auto sink_loop = seastar::async([sink] () mutable {
                for (auto i = 0; i < 100; i++) {
                    sink("seastar").get();
                    sleep(std::chrono::milliseconds(1)).get();
                }
            }).finally([sink] () mutable {
                return sink.flush();
            }).finally([sink] () mutable {
                return sink.close();
            }).finally([sink] {});

            auto source_loop = seastar::async([source, &r] () mutable {
                while (!r.server_source_closed) {
                    auto data = source().get();
                    if (data) {
                        r.server_sum += std::get<0>(*data);
                    } else {
                        r.server_source_closed = true;
                        try {
                          // check that reading after eos does not crash
                          // and throws correct exception
                           source().get();
                        } catch (rpc::stream_closed& ex) {
                          // expected
                        } catch (...) {
                           BOOST_FAIL("wrong exception on reading from a stream after eos");
                        }
                    }
                }
            });
            server_done = when_all_succeed(std::move(sink_loop), std::move(source_loop)).discard_result();
            return sink;
        }).get();
        auto call = env.proto().make_client<rpc::source<sstring> (int, rpc::sink<int>)>(1);
        struct failed_to_create_sync{};
        auto x = [&] {
            try {
                return c.make_stream_sink<serializer, int>(env.make_socket()).get();
            } catch (...) {
                c.stop().get();
                throw failed_to_create_sync{};
            }
        };
        try {
            auto sink = x();
            auto source = call(c, 666, sink).get();
            auto source_done = seastar::async([&] {
                while (!r.client_source_closed) {
                    auto data = source().get();
                    if (data) {
                        BOOST_REQUIRE_EQUAL(std::get<0>(*data), "seastar");
                    } else {
                        r.client_source_closed = true;
                    }
                }
            });
            auto check_exception = [] (auto f) {
                try {
                    f.get();
                } catch (...) {
                    return true;
                }
                return false;
            };
            future<> stop_client_future = make_ready_future();
            future<> stop_server_future = make_ready_future();
            // With a connection error sink() will eventually fail, but we
            // cannot guarantee when.
            int max = expect_connection_error ? std::numeric_limits<int>::max()  : 101;
            for (int i = 1; i < max; i++) {
                if (i == 50) {
                    if (stop_client) {
                        // stop client while stream is in use
                        stop_client_future = c.stop();
                    }
                    if (stop_server) {
                        // stop server while stream is in use
                        stop_server_future = env.server().shutdown();
                    }
                }
                sleep(std::chrono::milliseconds(1)).get();
                r.sink_exception = check_exception(sink(i));
                if (r.sink_exception) {
                    break;
                }
            }
            r.sink_close_exception = check_exception(sink.close());
            r.source_done_exception = check_exception(std::move(source_done));
            r.server_done_exception = check_exception(std::move(server_done));
            r.client_stop_exception = check_exception(!stop_client ? c.stop() : std::move(stop_client_future));
            r.server_stop_exception = check_exception(!stop_server ? make_ready_future<>() : std::move(stop_server_future));
            return r;
        } catch(failed_to_create_sync&) {
            r.exception_while_creating_sink = true;
            return r;
        }
    });
}

SEASTAR_TEST_CASE(test_stream_simple) {
    rpc::server_options so;
    so.streaming_domain = rpc::streaming_domain_type(1);
    rpc_test_config cfg;
    cfg.server_options = so;
    return rpc_test_env<>::do_with(cfg, [] (rpc_test_env<>& env) {
        return stream_test_func(env, false, false).then([] (stream_test_result r) {
            BOOST_REQUIRE(r.client_source_closed);
            BOOST_REQUIRE(r.server_source_closed);
            BOOST_REQUIRE(r.server_sum == 5050);
            BOOST_REQUIRE(!r.sink_exception);
            BOOST_REQUIRE(!r.sink_close_exception);
            BOOST_REQUIRE(!r.source_done_exception);
            BOOST_REQUIRE(!r.server_done_exception);
            BOOST_REQUIRE(!r.client_stop_exception);
        });
    });
}

SEASTAR_TEST_CASE(test_stream_stop_client) {
    rpc::server_options so;
    so.streaming_domain = rpc::streaming_domain_type(1);
    rpc_test_config cfg;
    cfg.server_options = so;
    return rpc_test_env<>::do_with(cfg, [] (rpc_test_env<>& env) {
        return stream_test_func(env, true, false).then([] (stream_test_result r) {
            BOOST_REQUIRE(!r.client_source_closed);
            BOOST_REQUIRE(!r.server_source_closed);
            BOOST_REQUIRE(r.sink_exception);
            BOOST_REQUIRE(r.sink_close_exception);
            BOOST_REQUIRE(r.source_done_exception);
            BOOST_REQUIRE(r.server_done_exception);
            BOOST_REQUIRE(!r.client_stop_exception);
        });
    });
}

SEASTAR_TEST_CASE(test_stream_stop_server) {
    rpc::server_options so;
    so.streaming_domain = rpc::streaming_domain_type(1);
    rpc_test_config cfg;
    cfg.server_options = so;
    return rpc_test_env<>::do_with(cfg, [] (rpc_test_env<>& env) {
        return stream_test_func(env, false, true).then([] (stream_test_result r) {
            BOOST_REQUIRE(!r.client_source_closed);
            BOOST_REQUIRE(!r.server_source_closed);
            BOOST_REQUIRE(r.sink_exception);
            BOOST_REQUIRE(r.sink_close_exception);
            BOOST_REQUIRE(r.source_done_exception);
            BOOST_REQUIRE(r.server_done_exception);
            BOOST_REQUIRE(!r.client_stop_exception);
            BOOST_REQUIRE(!r.server_stop_exception);
        });
    });
}

SEASTAR_TEST_CASE(test_stream_connection_error) {
    rpc::server_options so;
    so.streaming_domain = rpc::streaming_domain_type(1);
    rpc_test_config cfg;
    cfg.server_options = so;
    rpc_loopback_error_injector::config ecfg;
    ecfg.server_rcv.limit = 50;
    ecfg.server_rcv.kind = loopback_error_injector::error::abort;
    cfg.inject_error = ecfg;
    return rpc_test_env<>::do_with(cfg, [] (rpc_test_env<>& env) {
        return stream_test_func(env, false, false, true).then([] (stream_test_result r) {
            BOOST_REQUIRE(!r.client_source_closed);
            BOOST_REQUIRE(!r.server_source_closed);
            BOOST_REQUIRE(r.sink_exception);
            BOOST_REQUIRE(r.sink_close_exception);
            BOOST_REQUIRE(r.source_done_exception);
            BOOST_REQUIRE(r.server_done_exception);
            BOOST_REQUIRE(!r.client_stop_exception);
        });
    });
}

SEASTAR_TEST_CASE(test_stream_negotiation_error) {
    rpc::server_options so;
    so.streaming_domain = rpc::streaming_domain_type(1);
    rpc_test_config cfg;
    cfg.server_options = so;
    rpc_loopback_error_injector::config ecfg;
    ecfg.server_rcv.limit = 0;
    ecfg.server_rcv.kind = loopback_error_injector::error::abort;
    cfg.inject_error = ecfg;
    return rpc_test_env<>::do_with(cfg, [] (rpc_test_env<>& env) {
        return stream_test_func(env, false, false, true).then([] (stream_test_result r) {
            BOOST_REQUIRE(r.exception_while_creating_sink);
        });
    });
}

static future<> test_rpc_connection_send_glitch(bool on_client) {
    struct context {
        int limit;
        bool no_failures;
        bool on_client;
    };

    return do_with(context{0, false, on_client}, [] (auto& ctx) {
        return do_until([&ctx] {
            return ctx.no_failures;
        }, [&ctx] {
            fmt::print("======== 8< ========\n");
            fmt::print("  Checking {} limit\n", ctx.limit);
            rpc_test_config cfg;
            rpc_loopback_error_injector::config ecfg;
            if (ctx.on_client) {
                ecfg.client_snd.limit = ctx.limit;
                ecfg.client_snd.kind = loopback_error_injector::error::one_shot;
            } else {
                ecfg.server_snd.limit = ctx.limit;
                ecfg.server_snd.kind = loopback_error_injector::error::one_shot;
            }
            cfg.inject_error = ecfg;
            return rpc_test_env<>::do_with_thread(cfg, [&ctx] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
                env.register_handler(1, [] {
                    fmt::print("  reply\n");
                    return seastar::sleep(std::chrono::milliseconds(100)).then([] {
                        return make_ready_future<unsigned>(13);
                    });
                }).get();

                ctx.no_failures = true;

                for (int i = 0; i < 4; i++) {
                    auto call = env.proto().make_client<unsigned ()>(1);
                    fmt::print("  call {}\n", i);
                    try {
                        auto id = call(c1).get();
                        fmt::print("    response: {}\n", id);
                    } catch (...) {
                        fmt::print("    responce: ex {}\n", std::current_exception());
                        ctx.no_failures = false;
                        ctx.limit++;
                        break;
                    }
                    seastar::yield().get();
                }
            });
        });
    });
}

SEASTAR_TEST_CASE(test_rpc_client_send_glitch) {
    return test_rpc_connection_send_glitch(true);
}

SEASTAR_TEST_CASE(test_rpc_server_send_glitch) {
    return test_rpc_connection_send_glitch(false);
}

SEASTAR_TEST_CASE(test_rpc_scheduling) {
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        auto sg = create_scheduling_group("rpc", 100).get();
        env.register_handler(1, sg, [] () {
            return make_ready_future<unsigned>(internal::scheduling_group_index(current_scheduling_group()));
        }).get();
        auto call_sg_id = env.proto().make_client<unsigned ()>(1);
        auto id = call_sg_id(c1).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg));
    });
}

SEASTAR_THREAD_TEST_CASE(test_rpc_scheduling_connection_based) {
    auto sg1 = create_scheduling_group("sg1", 100).get();
    auto sg1_kill = defer([&] () noexcept { destroy_scheduling_group(sg1).get(); });
    auto sg2 = create_scheduling_group("sg2", 100).get();
    auto sg2_kill = defer([&] () noexcept { destroy_scheduling_group(sg2).get(); });
    rpc::resource_limits limits;
    limits.isolate_connection = [sg1, sg2] (sstring cookie) {
        auto sg = current_scheduling_group();
        if (cookie == "sg1") {
            sg = sg1;
        } else if (cookie == "sg2") {
            sg = sg2;
        }
        rpc::isolation_config cfg;
        cfg.sched_group = sg;
        return cfg;
    };
    rpc_test_config cfg;
    cfg.resource_limits = limits;
    rpc_test_env<>::do_with_thread(cfg, [sg1, sg2] (rpc_test_env<>& env) {
        rpc::client_options co1;
        co1.isolation_cookie = "sg1";
        test_rpc_proto::client c1(env.proto(), co1, env.make_socket(), ipv4_addr());
        rpc::client_options co2;
        co2.isolation_cookie = "sg2";
        test_rpc_proto::client c2(env.proto(), co2, env.make_socket(), ipv4_addr());
        env.register_handler(1, [] {
            return make_ready_future<unsigned>(internal::scheduling_group_index(current_scheduling_group()));
        }).get();
        auto call_sg_id = env.proto().make_client<unsigned ()>(1);
        unsigned id;
        id = call_sg_id(c1).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg1));
        id = call_sg_id(c2).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg2));
        c1.stop().get();
        c2.stop().get();
    }).get();
}

SEASTAR_THREAD_TEST_CASE(test_rpc_scheduling_connection_based_compatibility) {
    auto sg1 = create_scheduling_group("sg1", 100).get();
    auto sg1_kill = defer([&] () noexcept { destroy_scheduling_group(sg1).get(); });
    auto sg2 = create_scheduling_group("sg2", 100).get();
    auto sg2_kill = defer([&] () noexcept { destroy_scheduling_group(sg2).get(); });
    rpc::resource_limits limits;
    limits.isolate_connection = [sg1, sg2] (sstring cookie) {
        auto sg = current_scheduling_group();
        if (cookie == "sg1") {
            sg = sg1;
        } else if (cookie == "sg2") {
            sg = sg2;
        }
        rpc::isolation_config cfg;
        cfg.sched_group = sg;
        return cfg;
    };
    rpc_test_config cfg;
    cfg.resource_limits = limits;
    rpc_test_env<>::do_with_thread(cfg, [sg1, sg2] (rpc_test_env<>& env) {
        rpc::client_options co1;
        co1.isolation_cookie = "sg1";
        test_rpc_proto::client c1(env.proto(), co1, env.make_socket(), ipv4_addr());
        rpc::client_options co2;
        co2.isolation_cookie = "sg2";
        test_rpc_proto::client c2(env.proto(), co2, env.make_socket(), ipv4_addr());
        // An old client, that doesn't have an isolation cookie
        rpc::client_options co3;
        test_rpc_proto::client c3(env.proto(), co3, env.make_socket(), ipv4_addr());
        // A server that uses sg1 if the client is old
        env.register_handler(1, sg1, [] () {
            return make_ready_future<unsigned>(internal::scheduling_group_index(current_scheduling_group()));
        }).get();
        auto call_sg_id = env.proto().make_client<unsigned ()>(1);
        unsigned id;
        id = call_sg_id(c1).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg1));
        id = call_sg_id(c2).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg2));
        id = call_sg_id(c3).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg1));
        c1.stop().get();
        c2.stop().get();
        c3.stop().get();
    }).get();
}

SEASTAR_THREAD_TEST_CASE(test_rpc_scheduling_connection_based_async) {
    scheduling_group sg1 = default_scheduling_group();
    scheduling_group sg2 = default_scheduling_group();
    auto sg1_kill = defer([&] () noexcept {
        if (sg1 != default_scheduling_group())  {
            destroy_scheduling_group(sg1).get();
        }
    });
    auto sg2_kill = defer([&] () noexcept {
        if (sg2 != default_scheduling_group()) {
            destroy_scheduling_group(sg2).get();
        }
    });
    rpc::resource_limits limits;
    limits.isolate_connection = [&sg1, &sg2] (sstring cookie) {
        future<seastar::scheduling_group> get_scheduling_group = make_ready_future<>().then([&sg1, &sg2, cookie] {
            if (cookie == "sg1") {
                if (sg1 == default_scheduling_group()) {
                    return create_scheduling_group("sg1", 100).then([&sg1] (seastar::scheduling_group sg) {
                        sg1 = sg;
                        return sg;
                    });
                } else {
                    return make_ready_future<seastar::scheduling_group>(sg1);
                }
            } else if (cookie == "sg2") {
                if (sg2 == default_scheduling_group()) {
                    return create_scheduling_group("sg2", 100).then([&sg2] (seastar::scheduling_group sg) {
                        sg2 = sg;
                        return sg;
                    });
                } else {
                    return make_ready_future<seastar::scheduling_group>(sg2);
                }
            }
            return make_ready_future<seastar::scheduling_group>(current_scheduling_group());
        });

        return get_scheduling_group.then([] (scheduling_group sg) {
            rpc::isolation_config cfg;
            cfg.sched_group = sg;
            return cfg;
        });
    };
    rpc_test_config cfg;
    cfg.resource_limits = limits;
    rpc_test_env<>::do_with_thread(cfg, [&sg1, &sg2] (rpc_test_env<>& env) {
        rpc::client_options co1;
        co1.isolation_cookie = "sg1";
        test_rpc_proto::client c1(env.proto(), co1, env.make_socket(), ipv4_addr());
        rpc::client_options co2;
        co2.isolation_cookie = "sg2";
        test_rpc_proto::client c2(env.proto(), co2, env.make_socket(), ipv4_addr());
        env.register_handler(1, [] {
            return make_ready_future<unsigned>(internal::scheduling_group_index(current_scheduling_group()));
        }).get();
        auto call_sg_id = env.proto().make_client<unsigned ()>(1);
        unsigned id;
        id = call_sg_id(c1).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg1));
        id = call_sg_id(c2).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg2));
        c1.stop().get();
        c2.stop().get();
    }).get();
}

SEASTAR_THREAD_TEST_CASE(test_rpc_scheduling_connection_based_compatibility_async) {
    scheduling_group sg1 = default_scheduling_group();
    scheduling_group sg2 = default_scheduling_group();
    scheduling_group sg3 = create_scheduling_group("sg3", 100).get();
    auto sg1_kill = defer([&] () noexcept {
        if (sg1 != default_scheduling_group())  {
            destroy_scheduling_group(sg1).get();
        }
    });
    auto sg2_kill = defer([&] () noexcept {
        if (sg2 != default_scheduling_group()) {
            destroy_scheduling_group(sg2).get();
        }
    });
    auto sg3_kill = defer([&] () noexcept { destroy_scheduling_group(sg3).get(); });
    rpc::resource_limits limits;
    limits.isolate_connection = [&sg1, &sg2] (sstring cookie) {
        future<seastar::scheduling_group> get_scheduling_group = make_ready_future<>().then([&sg1, &sg2, cookie] {
            if (cookie == "sg1") {
                if (sg1 == default_scheduling_group()) {
                    return create_scheduling_group("sg1", 100).then([&sg1] (seastar::scheduling_group sg) {
                        sg1 = sg;
                        return sg;
                    });
                } else {
                    return make_ready_future<seastar::scheduling_group>(sg1);
                }
            } else if (cookie == "sg2") {
                if (sg2 == default_scheduling_group()) {
                    return create_scheduling_group("sg2", 100).then([&sg2] (seastar::scheduling_group sg) {
                        sg2 = sg;
                        return sg;
                    });
                } else {
                    return make_ready_future<seastar::scheduling_group>(sg2);
                }
            }
            return make_ready_future<seastar::scheduling_group>(current_scheduling_group());
        });

        return get_scheduling_group.then([] (scheduling_group sg) {
            rpc::isolation_config cfg;
            cfg.sched_group = sg;
            return cfg;
        });
    };
    rpc_test_config cfg;
    cfg.resource_limits = limits;
    rpc_test_env<>::do_with_thread(cfg, [&sg1, &sg2, &sg3] (rpc_test_env<>& env) {
        rpc::client_options co1;
        co1.isolation_cookie = "sg1";
        test_rpc_proto::client c1(env.proto(), co1, env.make_socket(), ipv4_addr());
        rpc::client_options co2;
        co2.isolation_cookie = "sg2";
        test_rpc_proto::client c2(env.proto(), co2, env.make_socket(), ipv4_addr());
        // An old client, that doesn't have an isolation cookie
        rpc::client_options co3;
        test_rpc_proto::client c3(env.proto(), co3, env.make_socket(), ipv4_addr());
        // A server that uses sg3 if the client is old
        env.register_handler(1, sg3, [] () {
            return make_ready_future<unsigned>(internal::scheduling_group_index(current_scheduling_group()));
        }).get();
        auto call_sg_id = env.proto().make_client<unsigned ()>(1);
        unsigned id;
        id = call_sg_id(c1).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg1));
        id = call_sg_id(c2).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg2));
        id = call_sg_id(c3).get();
        BOOST_REQUIRE(id == internal::scheduling_group_index(sg3));
        c1.stop().get();
        c2.stop().get();
        c3.stop().get();
    }).get();
}

void test_compressor(std::function<std::unique_ptr<seastar::rpc::compressor>()> compressor_factory) {
    using namespace seastar::rpc;

    auto linearize = [&] (const auto& buffer) {
        return seastar::visit(buffer.bufs,
            [] (const temporary_buffer<char>& buf) {
                return buf.clone();
            },
            [&] (const std::vector<temporary_buffer<char>>& bufs) {
                auto buf = temporary_buffer<char>(buffer.size);
                auto dst = buf.get_write();
                for (auto& b : bufs) {
                    dst = std::copy_n(b.get(), b.size(), dst);
                }
                return buf;
            }
        );
    };

    auto split_buffer = [&] (temporary_buffer<char> b, size_t chunk_size) {
        std::vector<temporary_buffer<char>> bufs;
        auto src = b.get();
        auto n = b.size();
        while (n) {
            auto this_chunk = std::min(chunk_size, n);
            bufs.emplace_back(this_chunk);
            std::copy_n(src, this_chunk, bufs.back().get_write());
            src += this_chunk;
            n -= this_chunk;
        }
        return bufs;
    };

    auto clone = [&] (const auto& buffer) {
        auto c = std::decay_t<decltype(buffer)>();
        c.size = buffer.size;
        c.bufs = seastar::visit(buffer.bufs,
            [] (const temporary_buffer<char>& buf) -> decltype(c.bufs) {
                return buf.clone();
            },
            [] (const std::vector<temporary_buffer<char>>& bufs) -> decltype(c.bufs) {
                std::vector<temporary_buffer<char>> c;
                c.reserve(bufs.size());
                for (auto& b : bufs) {
                    c.emplace_back(b.clone());
                }
                return c;
            }
        );
        return c;
    };

    auto compressor = compressor_factory();

    std::vector<noncopyable_function<std::tuple<sstring, size_t, snd_buf> ()>> inputs;

    auto add_input = [&] (auto func_returning_tuple) {
        inputs.emplace_back(std::move(func_returning_tuple));
    };

    auto& eng = testing::local_random_engine;
    auto dist = std::uniform_int_distribution<int>(0, std::numeric_limits<char>::max());

    auto snd = snd_buf(1);
    *snd.front().get_write() = 'a';
    add_input([snd = std::move(snd)] () mutable { return std::tuple(sstring("one byte, no headroom"), size_t(0), std::move(snd)); });

    snd = snd_buf(1);
    *snd.front().get_write() = 'a';
    add_input([snd = std::move(snd)] () mutable { return std::tuple(sstring("one byte, 128k of headroom"), size_t(128 * 1024), std::move(snd)); });

    auto gen_fill = [&](size_t s, sstring msg, std::optional<size_t> split = {}) {
        auto buf = temporary_buffer<char>(s);
        std::fill_n(buf.get_write(), s, 'a');

        auto snd = snd_buf();
        snd.size = s;
        if (split) {
            snd.bufs = split_buffer(buf.clone(), *split);
        } else {
            snd.bufs = buf.clone();
        }
        return std::tuple(msg, size_t(0), std::move(snd));
    };


    add_input(std::bind(gen_fill, 16 * 1024, "single 16 kB buffer of \'a\'"));

    auto gen_rand = [&](size_t s, sstring msg, std::optional<size_t> split = {}) {
        auto buf = temporary_buffer<char>(s);
        std::generate_n(buf.get_write(), s, [&] { return dist(eng); });

        auto snd = snd_buf();
        snd.size = s;
        if (split) {
            snd.bufs = split_buffer(buf.clone(), *split);
        } else {
            snd.bufs = buf.clone();
        }
        return std::tuple(msg, size_t(0), std::move(snd));
    };

    add_input(std::bind(gen_rand, 16 * 1024, "single 16 kB buffer of random"));

    auto gen_text = [&](size_t s, sstring msg, std::optional<size_t> split = {}) {
        static const std::string_view text = "The quick brown fox wants bananas for his long term health but sneaks bacon behind his wife's back. ";

        auto buf = temporary_buffer<char>(s);
        size_t n = 0;
        while (n < s) {
            auto rem = std::min(s - n, text.size());
            std::copy(text.data(), text.data() + rem, buf.get_write() + n);
            n += rem;
        }

        auto snd = snd_buf();
        snd.size = s;
        if (split) {
            snd.bufs = split_buffer(buf.clone(), *split);
        } else {
            snd.bufs = buf.clone();
        }
        return std::tuple(msg, size_t(0), std::move(snd));
    };

#ifndef SEASTAR_DEBUG
    auto buffer_sizes = { 1, 4 };
#else
    auto buffer_sizes = { 1 };
#endif

    for (auto s : buffer_sizes) {
        for (auto ss : { 32, 64, 128, 48, 56, 246, 511 }) {
            add_input(std::bind(gen_fill, s * 1024 * 1024, format("{} MB buffer of \'a\' split into {} kB - {}", s, ss, ss), ss * 1024 - ss));
            add_input(std::bind(gen_fill, s * 1024 * 1024, format("{} MB buffer of \'a\' split into {} kB", s, ss), ss * 1024));
            add_input(std::bind(gen_rand, s * 1024 * 1024, format("{} MB buffer of random split into {} kB", s, ss), ss * 1024));

            add_input(std::bind(gen_fill, s * 1024 * 1024 + 1, format("{} MB + 1B buffer of \'a\' split into {} kB", s, ss), ss * 1024));
            add_input(std::bind(gen_rand, s * 1024 * 1024 + 1, format("{} MB + 1B buffer of random split into {} kB", s, ss), ss * 1024));
        }

        for (auto ss : { 128, 246, 511, 3567, 2*1024, 8*1024 }) {
            add_input(std::bind(gen_fill, s * 1024 * 1024, format("{} MB buffer of \'a\' split into {} B", s, ss), ss));
            add_input(std::bind(gen_rand, s * 1024 * 1024, format("{} MB buffer of random split into {} B", s, ss), ss));
            add_input(std::bind(gen_text, s * 1024 * 1024, format("{} MB buffer of text split into {} B", s, ss), ss));
            add_input(std::bind(gen_fill, s * 1024 * 1024 - ss, format("{} MB - {}B buffer of \'a\' split into {} B", s, ss, ss), ss));
            add_input(std::bind(gen_rand, s * 1024 * 1024 - ss, format("{} MB - {}B buffer of random split into {} B", s, ss, ss), ss));
            add_input(std::bind(gen_text, s * 1024 * 1024 - ss, format("{} MB - {}B buffer of random split into {} B", s, ss, ss), ss));
        }
    }

    for (auto s : { 64*1024 + 5670, 16*1024 + 3421, 32*1024 - 321 }) {
        add_input(std::bind(gen_fill, s, format("{} bytes buffer of \'a\'", s)));
        add_input(std::bind(gen_rand, s, format("{} bytes buffer of random", s)));
        add_input(std::bind(gen_text, s, format("{} bytes buffer of text", s)));
    }

    std::vector<std::tuple<sstring, std::function<rcv_buf(snd_buf)>>> transforms {
        { "identity", [] (snd_buf snd) {
            rcv_buf rcv;
            rcv.size = snd.size;
            rcv.bufs = std::move(snd.bufs);
            return rcv;
        } },
        { "linearized", [&linearize] (snd_buf snd) {
            rcv_buf rcv;
            rcv.size = snd.size;
            rcv.bufs = linearize(snd);
            return rcv;
        } },
        { "split 1 B", [&] (snd_buf snd) {
            rcv_buf rcv;
            rcv.size = snd.size;
            rcv.bufs = split_buffer(linearize(snd), 1);
            return rcv;
        } },
        { "split 129 B", [&] (snd_buf snd) {
            rcv_buf rcv;
            rcv.size = snd.size;
            rcv.bufs = split_buffer(linearize(snd), 129);
            return rcv;
        } },
        { "split 4 kB", [&] (snd_buf snd) {
            rcv_buf rcv;
            rcv.size = snd.size;
            rcv.bufs = split_buffer(linearize(snd), 4096);
            return rcv;
        } },
        { "split 4 kB - 128", [&] (snd_buf snd) {
            rcv_buf rcv;
            rcv.size = snd.size;
            rcv.bufs = split_buffer(linearize(snd), 4096 - 128);
            return rcv;
        } },
    };

    auto sanity_check = [&] (const auto& buffer) {
        auto actual_size = seastar::visit(buffer.bufs,
            [] (const temporary_buffer<char>& buf) {
                return buf.size();
            },
            [] (const std::vector<temporary_buffer<char>>& bufs) {
                return boost::accumulate(bufs, size_t(0), [] (size_t sz, const temporary_buffer<char>& buf) {
                    return sz + buf.size();
                });
            }
        );
        BOOST_CHECK_EQUAL(actual_size, buffer.size);
    };

    for (auto& in_func : inputs) {
        auto in = in_func();
        BOOST_TEST_MESSAGE("Input: " << std::get<0>(in));
        auto headroom = std::get<1>(in);
        auto compressed = compressor->compress(headroom, clone(std::get<2>(in)));
        sanity_check(compressed);

        // Remove headroom
        BOOST_CHECK_GE(compressed.size, headroom);
        compressed.size -= headroom;
        seastar::visit(compressed.bufs,
            [&] (temporary_buffer<char>& buf) {
                BOOST_CHECK_GE(buf.size(), headroom);
                buf.trim_front(headroom);
            },
            [&] (std::vector<temporary_buffer<char>>& bufs) {
                while (headroom) {
                    BOOST_CHECK(!bufs.empty());
                    auto to_remove = std::min(bufs.front().size(), headroom);
                    bufs.front().trim_front(to_remove);
                    if (bufs.front().empty() && bufs.size() > 1) {
                        bufs.erase(bufs.begin());
                    }
                    headroom -= to_remove;
                }
            }
        );

        auto in_l = linearize(std::get<2>(in));

        for (auto& t : transforms) {
            BOOST_TEST_MESSAGE("  Transform: " << std::get<0>(t));
            auto received = std::get<1>(t)(clone(compressed));

            auto decompressed = compressor->decompress(std::move(received));
            sanity_check(decompressed);

            BOOST_CHECK_EQUAL(decompressed.size, std::get<2>(in).size);

            auto out_l = linearize(decompressed);

            BOOST_CHECK_EQUAL(in_l.size(), out_l.size());
            BOOST_CHECK(in_l == out_l);
        }
    }
}

SEASTAR_THREAD_TEST_CASE(test_lz4_compressor) {
    test_compressor([] { return std::make_unique<rpc::lz4_compressor>(); });
}

SEASTAR_THREAD_TEST_CASE(test_lz4_fragmented_compressor) {
    test_compressor([] { return std::make_unique<rpc::lz4_fragmented_compressor>(); });
}

// Test reproducing issue #671: If timeout is time_point::max(), translating
// it to relative timeout in the sender and then back in the receiver, when
// these calculations happen across a millisecond boundary, overflowed the
// integer and mislead the receiver to think the requested timeout was
// negative, and cause it drop its response, so the RPC call never completed.
SEASTAR_TEST_CASE(test_max_absolute_timeout) {
    // The typical failure of this test is a hang. So we use semaphore to
    // stop the test either when it succeeds, or after a long enough hang.
    auto success = make_lw_shared<bool>(false);
    auto done = make_lw_shared<semaphore>(0);
    auto abrt = make_lw_shared<abort_source>();
    (void) seastar::sleep_abortable(std::chrono::seconds(3), *abrt).then([done, success] {
        done->signal(1);
    }).handle_exception([] (std::exception_ptr) {});
    rpc::client_options co;
    co.send_timeout_data = 1;
    (void)rpc_test_env<>::do_with_thread(rpc_test_config(), co, [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        env.register_handler(1, [](int a, int b) {
            return make_ready_future<int>(a+b);
        }).get();
        auto sum = env.proto().make_client<int (int, int)>(1);
        // The bug only reproduces if the calculation done on the sender
        // and receiver sides, happened across a millisecond boundary.
        // We can't control when it happens, so we just need to loop many
        // times, at least many milliseconds, to increase the probability
        // that we catch the bug. Experimentally, if we loop for 200ms, we
        // catch the bug in #671 virtually every time.
        auto until = seastar::lowres_clock::now() + std::chrono::milliseconds(200);
        while (seastar::lowres_clock::now() <= until) {
            auto result = sum(c1, rpc::rpc_clock_type::time_point::max(), 2, 3).get();
            BOOST_REQUIRE_EQUAL(result, 2 + 3);
        }
    }).then([success, done, abrt] {
        *success = true;
        abrt->request_abort();
        done->signal();
    });
    return done->wait().then([done, success] {
        BOOST_REQUIRE(*success);
    });
}

// Similar to the above test: Test that a relative timeout duration::max()
// also works, and again doesn't cause the timeout wrapping around to the
// past and causing dropped responses.
SEASTAR_TEST_CASE(test_max_relative_timeout) {
    // The typical failure of this test is a hang. So we use semaphore to
    // stop the test either when it succeeds, or after a long enough hang.
    auto success = make_lw_shared<bool>(false);
    auto done = make_lw_shared<semaphore>(0);
    auto abrt = make_lw_shared<abort_source>();
    (void) seastar::sleep_abortable(std::chrono::seconds(3), *abrt).then([done, success] {
        done->signal(1);
    }).handle_exception([] (std::exception_ptr) {});
    rpc::client_options co;
    co.send_timeout_data = 1;
    (void)rpc_test_env<>::do_with_thread(rpc_test_config(), co, [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        env.register_handler(1, [](int a, int b) {
            return make_ready_future<int>(a+b);
        }).get();
        auto sum = env.proto().make_client<int (int, int)>(1);
        // The following call used to always hang, when max()+now()
        // overflowed and appeared to be a negative timeout.
        auto result = sum(c1, rpc::rpc_clock_type::duration::max(), 2, 3).get();
        BOOST_REQUIRE_EQUAL(result, 2 + 3);
    }).then([success, done, abrt] {
        *success = true;
        abrt->request_abort();
        done->signal();
    });
    return done->wait().then([done, success] {
        BOOST_REQUIRE(*success);
    });
}

SEASTAR_TEST_CASE(test_rpc_tuple) {
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        env.register_handler(1, [] () {
            return make_ready_future<rpc::tuple<int, long>>(rpc::tuple<int, long>(1, 0x7'0000'0000L));
        }).get();
        auto f1 = env.proto().make_client<rpc::tuple<int, long> ()>(1);
        auto result = f1(c1).get();
        BOOST_REQUIRE_EQUAL(std::get<0>(result), 1);
        BOOST_REQUIRE_EQUAL(std::get<1>(result), 0x7'0000'0000L);
    });
}

SEASTAR_TEST_CASE(test_rpc_nonvariadic_client_variadic_server) {
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        // Server is variadic
        env.register_handler(1, [] () {
            return make_ready_future<rpc::tuple<int, long>>(rpc::tuple(1, 0x7'0000'0000L));
        }).get();
        // Client is non-variadic
        auto f1 = env.proto().make_client<future<rpc::tuple<int, long>> ()>(1);
        auto result = f1(c1).get();
        BOOST_REQUIRE_EQUAL(std::get<0>(result), 1);
        BOOST_REQUIRE_EQUAL(std::get<1>(result), 0x7'0000'0000L);
    });
}

SEASTAR_TEST_CASE(test_rpc_variadic_client_nonvariadic_server) {
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        // Server is nonvariadic
        env.register_handler(1, [] () {
            return make_ready_future<rpc::tuple<int, long>>(rpc::tuple<int, long>(1, 0x7'0000'0000L));
        }).get();
        // Client is variadic
        auto f1 = env.proto().make_client<future<rpc::tuple<int, long>> ()>(1);
        auto result = f1(c1).get();
        BOOST_REQUIRE_EQUAL(std::get<0>(result), 1);
        BOOST_REQUIRE_EQUAL(std::get<1>(result), 0x7'0000'0000L);
    });
}

SEASTAR_TEST_CASE(test_handler_registration) {
    rpc_test_config cfg;
    rpc_loopback_error_injector::config ecfg;
    ecfg.connect_kind = loopback_error_injector::error::abort;
    cfg.inject_error = ecfg;
    return rpc_test_env<>::do_with_thread(cfg, [] (rpc_test_env<>& env) {
        auto& proto = env.proto();

        // new proto must be empty
        BOOST_REQUIRE(!proto.has_handlers());

        // non-existing handler should not be found
        BOOST_REQUIRE(!proto.has_handler(1));

        // unregistered non-existing handler should return ready future
        auto fut = proto.unregister_handler(1);
        BOOST_REQUIRE(fut.available() && !fut.failed());
        fut.get();

        // existing handler should be found
        auto handler = [] () { return make_ready_future<>(); };
        proto.register_handler(1, handler);
        BOOST_REQUIRE(proto.has_handler(1));

        // cannot register handler if already registered
        BOOST_REQUIRE_THROW(proto.register_handler(1, handler), std::runtime_error);

        // unregistered handler should not be found
        proto.unregister_handler(1).get();
        BOOST_REQUIRE(!proto.has_handler(1));

        // re-registering a handler should succeed
        proto.register_handler(1, handler);
        BOOST_REQUIRE(proto.has_handler(1));

        // proto with handlers must not be empty
        BOOST_REQUIRE(proto.has_handlers());
    });
}

SEASTAR_TEST_CASE(test_unregister_handler) {
    using namespace std::chrono_literals;
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        promise<> handler_called;
        future<> f_handler_called = handler_called.get_future();
        bool rpc_executed = false;
        bool rpc_completed = false;

        auto reset_state = [&f_handler_called, &rpc_executed, &rpc_completed] {
            if (f_handler_called.available()) {
                f_handler_called.get();
            }
            rpc_executed = false;
            rpc_completed = false;
        };

        auto get_handler = [&handler_called, &rpc_executed, &rpc_completed] {
            return [&handler_called, &rpc_executed, &rpc_completed] {
                handler_called.set_value();
                rpc_executed = true;
                return sleep(1ms).then([&rpc_completed] {
                    rpc_completed = true;
                });
            };
        };

        // handler should not run if unregistered before being called
        env.register_handler(1, get_handler()).get();
        env.unregister_handler(1).get();
        BOOST_REQUIRE(!f_handler_called.available());
        BOOST_REQUIRE(!rpc_executed);
        BOOST_REQUIRE(!rpc_completed);

        // verify normal execution path
        env.register_handler(1, get_handler()).get();
        auto call = env.proto().make_client<void ()>(1);
        call(c1).get();
        BOOST_REQUIRE(f_handler_called.available());
        BOOST_REQUIRE(rpc_executed);
        BOOST_REQUIRE(rpc_completed);
        reset_state();

        // call should fail after handler is unregistered
        env.unregister_handler(1).get();
        try {
            call(c1).get();
            BOOST_REQUIRE(false);
        } catch (rpc::unknown_verb_error&) {
            // expected
        } catch (...) {
            std::cerr << "call failed in an unexpected way: " << std::current_exception() << std::endl;
            BOOST_REQUIRE(false);
        }
        BOOST_REQUIRE(!f_handler_called.available());
        BOOST_REQUIRE(!rpc_executed);
        BOOST_REQUIRE(!rpc_completed);

        // unregistered is allowed while call is in flight
        auto delayed_unregister = [&env] {
            return sleep(500us).then([&env] {
                return env.unregister_handler(1);
            });
        };

        env.register_handler(1, get_handler()).get();
        try {
            when_all_succeed(call(c1), delayed_unregister()).get();
            reset_state();
        } catch (rpc::unknown_verb_error&) {
            // expected
        } catch (...) {
            std::cerr << "call failed in an unexpected way: " << std::current_exception() << std::endl;
            BOOST_REQUIRE(false);
        }

        // verify that unregister_handler waits for pending requests to finish
        {
            promise<> handler_reached_promise;
            promise<> handler_go_promise;
            sstring value_to_return = "before_unregister";
            env.register_handler(1, [&]() -> future<sstring> {
                handler_reached_promise.set_value();
                return handler_go_promise.get_future().then([&] { return value_to_return; });
            }).get();
            auto f = env.proto().make_client<future<sstring>()>(1);
            auto response_future = f(c1);
            handler_reached_promise.get_future().get();
            auto unregister_future = env.unregister_handler(1).then([&] {
                value_to_return = "after_unregister";
            });
            BOOST_REQUIRE(!unregister_future.available());
            sleep(1ms).get();
            BOOST_REQUIRE(!unregister_future.available());
            handler_go_promise.set_value();
            unregister_future.get();
            BOOST_REQUIRE_EQUAL(response_future.get(), "before_unregister");
        }
    });
}

SEASTAR_TEST_CASE(test_loggers) {
    static seastar::logger log("dummy");
    log.set_level(log_level::debug);
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env, test_rpc_proto::client& c1) {
        socket_address dummy_addr;
        auto& proto = env.proto();
        auto& logger = proto.get_logger();
        logger(dummy_addr, "Hello0");
        logger(dummy_addr, log_level::debug, "Hello1");
        proto.set_logger(&log);
        logger(dummy_addr, "Hello2");
        logger(dummy_addr, log_level::debug, "Hello3");
        // We *want* to test the deprecated API, don't spam warnings about it.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
        proto.set_logger([] (const sstring& str) {
            log.info("Test: {}", str);
        });
#pragma GCC diagnostic pop
        logger(dummy_addr, "Hello4");
        logger(dummy_addr, log_level::debug, "Hello5");
        proto.set_logger(nullptr);
        logger(dummy_addr, "Hello6");
        logger(dummy_addr, log_level::debug, "Hello7");
    });
}

SEASTAR_TEST_CASE(test_connection_id_format) {
    rpc::connection_id cid = rpc::connection_id::make_id(0x123, 1);
    std::string res = format("{}", cid);
    BOOST_REQUIRE_EQUAL(res, "1230001");
    return make_ready_future<>();
}

static_assert(std::is_same_v<decltype(rpc::tuple(1U, 1L)), rpc::tuple<unsigned, long>>, "rpc::tuple deduction guid not working");

SEASTAR_TEST_CASE(test_client_info) {
    return rpc_test_env<>::do_with(rpc_test_config(), [] (rpc_test_env<>& env) {
        rpc::client_info info{.server{env.server()}, .conn_id{0}};
        const rpc::client_info& const_info = *const_cast<rpc::client_info*>(&info);

        info.attach_auxiliary("key", 0);
        BOOST_REQUIRE_EQUAL(const_info.retrieve_auxiliary<int>("key"), 0);
        info.retrieve_auxiliary<int>("key") = 1;
        BOOST_REQUIRE_EQUAL(const_info.retrieve_auxiliary<int>("key"), 1);

        BOOST_REQUIRE_EQUAL(info.retrieve_auxiliary_opt<int>("key"), &info.retrieve_auxiliary<int>("key"));
        BOOST_REQUIRE_EQUAL(const_info.retrieve_auxiliary_opt<int>("key"), &const_info.retrieve_auxiliary<int>("key"));

        BOOST_REQUIRE_EQUAL(info.retrieve_auxiliary_opt<int>("missing"), nullptr);
        BOOST_REQUIRE_EQUAL(const_info.retrieve_auxiliary_opt<int>("missing"), nullptr);

        return make_ready_future<>();
    });
}

void send_messages_and_check_timeouts(rpc_test_env<>& env, test_rpc_proto::client& cln) {
    env.register_handler(1, [](int v) {
        return seastar::sleep(std::chrono::seconds(v)).then([v] {
            return make_ready_future<int>(v);
        });
    }).get();

    auto call = env.proto().template make_client<int(int)>(1);
    auto start = std::chrono::steady_clock::now();
    auto f1 = call(cln, std::chrono::milliseconds(400), 3).finally([start] {
        auto end = std::chrono::steady_clock::now();
        BOOST_REQUIRE(end - start < std::chrono::seconds(1));
    });
    auto f2 = call(cln, std::chrono::milliseconds(600), 3).finally([start] {
        auto end = std::chrono::steady_clock::now();
        BOOST_REQUIRE(end - start < std::chrono::seconds(1));
    });
    BOOST_REQUIRE_THROW(f1.get(), seastar::rpc::timeout_error);
    BOOST_REQUIRE_THROW(f2.get(), seastar::rpc::timeout_error);
}

SEASTAR_TEST_CASE(test_rpc_send_timeout) {
    rpc_test_config cfg;
    return rpc_test_env<>::do_with_thread(cfg, [] (auto& env, auto& cln) {
        send_messages_and_check_timeouts(env, cln);
    });
}

SEASTAR_TEST_CASE(test_rpc_send_timeout_on_connect) {
    rpc_test_config cfg;
    rpc_loopback_error_injector::config ecfg;
    ecfg.connect_delay = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::seconds(5));
    cfg.inject_error = ecfg;
    return rpc_test_env<>::do_with_thread(cfg, [] (auto& env, auto& cln) {
        send_messages_and_check_timeouts(env, cln);
    });
}

SEASTAR_TEST_CASE(test_rpc_abort_connection) {
    return rpc_test_env<>::do_with_thread(rpc_test_config(), [] (rpc_test_env<>& env) {
        test_rpc_proto::client c1(env.proto(), {}, env.make_socket(), ipv4_addr());
        int arrived = 0;
        env.register_handler(1, [&arrived] (rpc::client_info& cinfo, int x) {
            BOOST_REQUIRE_EQUAL(x, arrived++);
            if (arrived == 2) {
                cinfo.server.abort_connection(cinfo.conn_id);
            }
            // The third message won't arrive because we abort the connection.

            return 0;
        }).get();
        auto f = env.proto().make_client<int (int)>(1);
        BOOST_REQUIRE_EQUAL(f(c1, 0).get(), 0);
        BOOST_REQUIRE_THROW(f(c1, 1).get(), rpc::closed_error);
        BOOST_REQUIRE_THROW(f(c1, 2).get(), rpc::closed_error);
        BOOST_REQUIRE_EQUAL(arrived, 2);
        c1.stop().get();
    });
}

SEASTAR_THREAD_TEST_CASE(test_rpc_metric_domains) {
    auto do_one_echo = [] (rpc_test_env<>& env, test_rpc_proto::client& cln, int nr_calls) {
        env.register_handler(1, [] (int v) { return make_ready_future<int>(v); }).get();
        auto call = env.proto().template make_client<int(int)>(1);
        for (int i = 0; i < nr_calls; i++) {
            call(cln, i).get();
        }
    };

    rpc::client_options client_opt;

    client_opt.metrics_domain = "dom1";
    auto p1 = rpc_test_env<>::do_with_thread(rpc_test_config(), client_opt, [&] (auto& env, auto& cln) { do_one_echo(env, cln, 3); });
    client_opt.metrics_domain = "dom2";
    auto p2 = rpc_test_env<>::do_with_thread(rpc_test_config(), client_opt, [&] (auto& env, auto& cln) { do_one_echo(env, cln, 2); });
    auto p3 = rpc_test_env<>::do_with_thread(rpc_test_config(), client_opt, [&] (auto& env, auto& cln) { do_one_echo(env, cln, 5); });
    when_all(std::move(p1), std::move(p2), std::move(p3)).discard_result().get();

    auto get_metrics = [] (std::string name, std::string domain) -> int {
        const auto& values = seastar::metrics::impl::get_value_map();
        const auto& mf = values.find(name);
        BOOST_REQUIRE(mf != values.end());
        for (auto&& mi : mf->second) {
            for (auto&&li : mi.first) {
                if (li.first == "domain" && li.second == domain) {
                    return mi.second->get_function()().i();
                }
            }
        }
        BOOST_FAIL("cannot find requested metrics");
        return 0;
    };

    // Negotiation messages also count, so +1 for default domain and +2 for "dom" one
    BOOST_CHECK_EQUAL(get_metrics("rpc_client_sent_messages", "dom1"), 4);
    BOOST_CHECK_EQUAL(get_metrics("rpc_client_sent_messages", "dom2"), 9);
}

// Extract a piece of contiguous data from the front of the buffer (and trim the extracted front away).
template <typename T>
requires std::is_trivially_copyable_v<T>
T read_from_rcv_buf(rpc::rcv_buf& data) {
    if (data.size < sizeof(T)) {
        throw std::runtime_error("Truncated compressed RPC frame");
    }
    auto it = std::get_if<temporary_buffer<char>>(&data.bufs);
    if (!it) {
        it = std::get<std::vector<temporary_buffer<char>>>(data.bufs).data();
    }
    std::array<T, 1> out;
    auto out_span = std::as_writable_bytes(std::span(out)).subspan(0);
    while (out_span.size()) {
        size_t n = std::min<size_t>(out_span.size(), it->size());
        std::memcpy(static_cast<void*>(out_span.data()), it->get(), n);
        out_span = out_span.subspan(n);
        it->trim_front(n);
        ++it;
        data.size -= n;
    }
    return out[0];
}


// Test the use of empty compressed frames as a method of communication between compressors.
SEASTAR_THREAD_TEST_CASE(test_compressor_empty_frames) {
    static const sstring compressor_name = "TEST";
    struct tracker {
        struct compressor;
        compressor* _compressor;

        // When `send_metadata(x)` is called, this compressor sends a piece of metadata (x) to its peer,
        // by prepending it to an empty compressed frame.
        // It can be read from the peer with `receive_metadata()`.
        struct compressor : public rpc::compressor {
            tracker& _tracker;

            std::unique_ptr<rpc::compressor> _delegate;

            using metadata = uint64_t;
            std::deque<metadata> _send_queue;
            std::deque<metadata> _recv_queue;
            semaphore _metadata_received{0};

            std::function<future<>()> _send_empty_frame;
            condition_variable _needs_progress;
            future<> _progress_fiber;

            future<> start_progress_fiber() {
                while (true) {
                    co_await _needs_progress.when([&] { return !_send_queue.empty(); });
                    co_await _send_empty_frame();
                }
            }
            future<> close() noexcept override {
                _needs_progress.broken();
                return std::move(_progress_fiber).handle_exception([] (const auto&) {});
            }
            void send_metadata(metadata x) {
                _send_queue.push_back(x);
                _needs_progress.signal();
            }
            future<metadata> receive_metadata() {
                co_await _metadata_received.wait();
                auto x = _recv_queue.front();
                _recv_queue.pop_front();
                co_return x;
            }

            rpc::snd_buf compress(size_t head_space, rpc::snd_buf data) override {
                if (!_send_queue.empty()) {
                    auto x = _delegate->compress(head_space + 1 + sizeof(metadata), data.size ? std::move(data) : rpc::snd_buf(temporary_buffer<char>()));
                    seastar::write_be<uint8_t>(x.front().get_write()+head_space, 1);
                    seastar::write_be<uint64_t>(x.front().get_write()+head_space+1, _send_queue.front());
                    _send_queue.pop_front();
                    return x;
                } else {
                    auto x = _delegate->compress(head_space + 1, data.size ? std::move(data) : rpc::snd_buf(temporary_buffer<char>()));
                    seastar::write_be<uint8_t>(x.front().get_write()+head_space, 0);
                    return x;
                }
            }
            rpc::rcv_buf decompress(rpc::rcv_buf data) override {
                if (net::ntoh(read_from_rcv_buf<uint8_t>(data))) {
                    _recv_queue.push_back(net::ntoh(read_from_rcv_buf<uint64_t>(data)));
                    _metadata_received.signal();
                }
                return _delegate->decompress(std::move(data));
            }
            sstring name() const override {
                return compressor_name;
            }

            compressor(tracker& tracker, std::function<future<>()> send_empty_frame)
                : _tracker(tracker)
                , _delegate(std::make_unique<rpc::lz4_fragmented_compressor>())
                , _send_empty_frame(std::move(send_empty_frame))
                , _progress_fiber(start_progress_fiber())
            {
                _tracker._compressor = this;
            }
            ~compressor() {
                _tracker._compressor = nullptr;
            }
        };

        struct factory : public rpc::compressor::factory {
            tracker& _tracker;

            factory(tracker& tracker) : _tracker(tracker) {
            }
            const sstring& supported() const override {
                return compressor_name;
            }
            std::unique_ptr<rpc::compressor> negotiate(sstring feature, bool is_server, std::function<future<>()> send_empty_frame) const override {
                if (feature == supported()) {
                    return std::make_unique<compressor>(_tracker, std::move(send_empty_frame));
                }
                return nullptr;
            }
            std::unique_ptr<rpc::compressor> negotiate(sstring feature, bool is_server) const override {
                abort();
            }
        };
    };

    tracker server_tracker;
    tracker client_tracker;
    tracker::factory server_factory{server_tracker};
    tracker::factory client_factory{client_tracker};
    rpc::server_options so{.compressor_factory = &server_factory};
    rpc::client_options co{.compressor_factory = &client_factory};
    rpc_test_config cfg;
    cfg.server_options = so;

    rpc_test_env<>::do_with_thread(cfg, co, [&] (rpc_test_env<>& env, test_rpc_proto::client& c) {
        // Perform an RPC once to initialize the connection and compressors. 
        env.register_handler(1, []() { return 42; }).get();
        auto proto_client = env.proto().make_client<int()>(1);
        BOOST_REQUIRE_EQUAL(proto_client(c).get(), 42);
        BOOST_REQUIRE(client_tracker._compressor);
        BOOST_REQUIRE(server_tracker._compressor);
        // Check that both compressors can send metadata to each other.
        for (int i = 0; i < 3; ++i) {
            client_tracker._compressor->send_metadata(2*i);
            BOOST_REQUIRE_EQUAL(server_tracker._compressor->receive_metadata().get(), 2*i);
            server_tracker._compressor->send_metadata(2*i+1);
            BOOST_REQUIRE_EQUAL(client_tracker._compressor->receive_metadata().get(), 2*i+1);
        }
    }).get();
}