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770e224917
- CI fix. - Renames request::fail_* to request::cancel_*. - Adds a second parameter to async_run. - Adds request::retry flag.
137 lines
4.1 KiB
C++
137 lines
4.1 KiB
C++
/* Copyright (c) 2018-2022 Marcelo Zimbres Silva (mzimbres@gmail.com)
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*
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* Distributed under the Boost Software License, Version 1.0. (See
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* accompanying file LICENSE.txt)
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*/
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#include <string>
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#include <vector>
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#include <iostream>
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#include <tuple>
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#include <boost/asio.hpp>
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#if defined(BOOST_ASIO_HAS_CO_AWAIT)
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#include <boost/asio/experimental/awaitable_operators.hpp>
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#include <aedis.hpp>
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#include "print.hpp"
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// Include this in no more than one .cpp file.
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#include <aedis/src.hpp>
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namespace net = boost::asio;
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using namespace net::experimental::awaitable_operators;
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using aedis::adapt;
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using aedis::resp3::request;
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using aedis::resp3::node;
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using aedis::endpoint;
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using tcp_socket = net::use_awaitable_t<>::as_default_on_t<net::ip::tcp::socket>;
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using stimer = net::use_awaitable_t<>::as_default_on_t<net::steady_timer>;
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using connection = aedis::connection<tcp_socket>;
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// Connects to a Redis instance over sentinel and performs failover in
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// case of disconnection, see
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// https://redis.io/docs/reference/sentinel-clients. This example
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// assumes a sentinel and a redis server running on localhost.
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net::awaitable<void> receive_pushes(std::shared_ptr<connection> conn)
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{
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for (std::vector<node<std::string>> resp;;) {
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co_await conn->async_receive(adapt(resp));
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print_push(resp);
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resp.clear();
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}
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}
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net::awaitable<endpoint> resolve()
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{
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// A list of sentinel addresses from which only one is responsive
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// to simulate sentinels that are down.
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std::vector<endpoint> const endpoints
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{ {"foo", "26379"}
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, {"bar", "26379"}
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, {"127.0.0.1", "26379"}
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};
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request req;
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req.get_config().cancel_if_not_connected = false;
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req.get_config().cancel_on_connection_lost = true;
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req.push("SENTINEL", "get-master-addr-by-name", "mymaster");
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req.push("QUIT");
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connection conn{co_await net::this_coro::executor};
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std::tuple<std::optional<std::array<std::string, 2>>, aedis::ignore> addr;
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for (auto ep : endpoints) {
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boost::system::error_code ec1, ec2;
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co_await (
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conn.async_run(ep, {}, net::redirect_error(net::use_awaitable, ec1)) &&
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conn.async_exec(req, adapt(addr), net::redirect_error(net::use_awaitable, ec2))
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);
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std::clog << "async_run: " << ec1.message() << "\n"
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<< "async_exec: " << ec2.message() << std::endl;
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conn.reset_stream();
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if (std::get<0>(addr))
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break;
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}
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endpoint ep;
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if (std::get<0>(addr)) {
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ep.host = std::get<0>(addr).value().at(0);
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ep.port = std::get<0>(addr).value().at(1);
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}
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co_return ep;
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}
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net::awaitable<void> reconnect(std::shared_ptr<connection> conn)
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{
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request req;
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req.get_config().cancel_if_not_connected = false;
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req.get_config().cancel_on_connection_lost = true;
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req.push("SUBSCRIBE", "channel");
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auto ex = co_await net::this_coro::executor;
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stimer timer{ex};
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for (;;) {
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auto ep = co_await net::co_spawn(ex, resolve(), net::use_awaitable);
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if (!aedis::is_valid(ep)) {
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std::clog << "Can't resolve master name" << std::endl;
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co_return;
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}
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boost::system::error_code ec1, ec2;
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co_await (
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conn->async_run(ep, {}, net::redirect_error(net::use_awaitable, ec1)) &&
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conn->async_exec(req, adapt(), net::redirect_error(net::use_awaitable, ec2))
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);
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std::clog << "async_run: " << ec1.message() << "\n"
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<< "async_exec: " << ec2.message() << "\n"
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<< "Starting the failover." << std::endl;
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timer.expires_after(std::chrono::seconds{1});
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co_await timer.async_wait();
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}
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}
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int main()
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{
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try {
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net::io_context ioc;
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auto conn = std::make_shared<connection>(ioc);
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net::co_spawn(ioc, receive_pushes(conn), net::detached);
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net::co_spawn(ioc, reconnect(conn), net::detached);
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net::signal_set signals(ioc, SIGINT, SIGTERM);
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signals.async_wait([&](auto, auto){ ioc.stop(); });
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ioc.run();
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} catch (std::exception const& e) {
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std::cerr << "Error: " << e.what() << std::endl;
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}
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}
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#else // defined(BOOST_ASIO_HAS_CO_AWAIT)
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int main() {std::cout << "Requires coroutine support." << std::endl; return 1;}
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#endif // defined(BOOST_ASIO_HAS_CO_AWAIT)
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