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Files
redis/examples/cpp20_resolve_with_sentinel.cpp
2023-03-14 20:11:22 +01:00

73 lines
2.2 KiB
C++

/* Copyright (c) 2018-2022 Marcelo Zimbres Silva (mzimbres@gmail.com)
*
* Distributed under the Boost Software License, Version 1.0. (See
* accompanying file LICENSE.txt)
*/
#include <boost/redis/run.hpp>
#include <boost/asio/use_awaitable.hpp>
#include <boost/asio/redirect_error.hpp>
#include <boost/asio/experimental/awaitable_operators.hpp>
#include <iostream>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
namespace net = boost::asio;
using namespace net::experimental::awaitable_operators;
using endpoints = net::ip::tcp::resolver::results_type;
using boost::redis::request;
using boost::redis::response;
using boost::redis::ignore_t;
using boost::redis::async_run;
using connection = boost::asio::use_awaitable_t<>::as_default_on_t<boost::redis::connection>;
auto redir(boost::system::error_code& ec)
{ return net::redirect_error(net::use_awaitable, ec); }
struct address {
std::string host;
std::string port;
};
// For more info see
// - https://redis.io/docs/manual/sentinel.
// - https://redis.io/docs/reference/sentinel-clients.
auto resolve_master_address(std::vector<address> const& endpoints) -> net::awaitable<address>
{
request req;
req.push("SENTINEL", "get-master-addr-by-name", "mymaster");
req.push("QUIT");
auto conn = std::make_shared<connection>(co_await net::this_coro::executor);
response<std::optional<std::array<std::string, 2>>, ignore_t> addr;
for (auto ep : endpoints) {
boost::system::error_code ec;
co_await (async_run(*conn, ep.host, ep.port) && conn->async_exec(req, addr, redir(ec)));
conn->reset_stream();
if (std::get<0>(addr))
co_return address{std::get<0>(addr).value().value().at(0), std::get<0>(addr).value().value().at(1)};
}
co_return address{};
}
auto co_main(std::string host, std::string port) -> net::awaitable<void>
{
// A list of sentinel addresses from which only one is responsive.
// This simulates sentinels that are down.
std::vector<address> const endpoints
{ {"foo", "26379"}
, {"bar", "26379"}
, {host, port}
};
auto const ep = co_await resolve_master_address(endpoints);
std::clog
<< "Host: " << ep.host << "\n"
<< "Port: " << ep.port << "\n"
<< std::flush;
}
#endif // defined(BOOST_ASIO_HAS_CO_AWAIT)