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cpp20_subscriber.cpp
1/* Copyright (c) 2018-2022 Marcelo Zimbres Silva (mzimbres@gmail.com)
2 *
3 * Distributed under the Boost Software License, Version 1.0. (See
4 * accompanying file LICENSE.txt)
5 */
6
7#include <boost/redis/connection.hpp>
8#include <boost/redis/logger.hpp>
9
10#include <boost/asio/awaitable.hpp>
11#include <boost/asio/co_spawn.hpp>
12#include <boost/asio/consign.hpp>
13#include <boost/asio/detached.hpp>
14#include <boost/asio/redirect_error.hpp>
15#include <boost/asio/signal_set.hpp>
16#include <boost/asio/use_awaitable.hpp>
17
18#include <iostream>
19
20#if defined(BOOST_ASIO_HAS_CO_AWAIT)
21
22namespace asio = boost::asio;
23using namespace std::chrono_literals;
26using boost::redis::consume_one;
31using boost::system::error_code;
33using asio::signal_set;
34
35/* This example will subscribe and read pushes indefinitely.
36 *
37 * To test send messages with redis-cli
38 *
39 * $ redis-cli -3
40 * 127.0.0.1:6379> PUBLISH channel some-message
41 * (integer) 3
42 * 127.0.0.1:6379>
43 *
44 * To test reconnection try, for example, to close all clients currently
45 * connected to the Redis instance
46 *
47 * $ redis-cli
48 * > CLIENT kill TYPE pubsub
49 */
50
51// Receives server pushes.
52auto receiver(std::shared_ptr<connection> conn) -> asio::awaitable<void>
53{
54 request req;
55 req.push("SUBSCRIBE", "channel");
56
58 conn->set_receive_response(resp);
59
60 // Loop while reconnection is enabled
61 while (conn->will_reconnect()) {
62 // Reconnect to the channels.
63 co_await conn->async_exec(req, ignore);
64
65 // Loop reading Redis pushs messages.
66 for (error_code ec;;) {
67 // First tries to read any buffered pushes.
68 conn->receive(ec);
69 if (ec == error::sync_receive_push_failed) {
70 ec = {};
71 co_await conn->async_receive(asio::redirect_error(asio::use_awaitable, ec));
72 }
73
74 if (ec)
75 break; // Connection lost, break so we can reconnect to channels.
76
77 std::cout << resp.value().at(1).value << " " << resp.value().at(2).value << " "
78 << resp.value().at(3).value << std::endl;
79
80 consume_one(resp);
81 }
82 }
83}
84
85auto co_main(config cfg) -> asio::awaitable<void>
86{
87 auto ex = co_await asio::this_coro::executor;
88 auto conn = std::make_shared<connection>(ex);
89 asio::co_spawn(ex, receiver(conn), asio::detached);
90 conn->async_run(cfg, asio::consign(asio::detached, conn));
91
92 signal_set sig_set(ex, SIGINT, SIGTERM);
93 co_await sig_set.async_wait();
94
95 conn->cancel();
96}
97
98#endif // defined(BOOST_ASIO_HAS_CO_AWAIT)
A basic_connection that type erases the executor.
Creates Redis requests.
Definition request.hpp:46
error
Generic errors.
Definition error.hpp:18
ignore_t ignore
Global ignore object.
adapter::result< std::vector< resp3::node > > generic_response
A generic response to a request.
Definition response.hpp:35
Configure parameters used by the connection classes.
Definition config.hpp:30
Defines logging configuration.
Definition logger.hpp:20