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88 lines
2.4 KiB
C++
88 lines
2.4 KiB
C++
/* Copyright (c) 2019 - 2021 Marcelo Zimbres Silva (mzimbres at gmail dot com)
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/.
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*/
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#include <iostream>
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#include <chrono>
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#include <optional>
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#include <aedis/aedis.hpp>
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#include "utils.ipp"
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using aedis::command;
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using aedis::resp3::serializer;
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using aedis::resp3::async_read;
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using aedis::resp3::adapt;
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using aedis::resp3::node;
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namespace net = aedis::net;
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using net::async_write;
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using net::buffer;
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/* Shows how to deal with keys that may not exist.
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When accessing a key that does not exist, for example due to
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expiration, redis will return null. Aedis supports these usecases
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through std::optional.
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*/
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net::awaitable<void> key_expiration()
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{
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try {
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auto socket = co_await connect();
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// Creates and sends the first request.
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serializer<command> sr;
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sr.push(command::hello, 3);
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sr.push(command::flushall);
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sr.push(command::set, "key", "Some payload", "EX", "2");
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sr.push(command::get, "key");
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co_await async_write(socket, buffer(sr.request()));
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// Will hold the response to get.
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std::optional<std::string> get;
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// Reads the responses.
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std::string aux_buffer;
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co_await async_read(socket, aux_buffer); // hello
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co_await async_read(socket, aux_buffer); // flushall
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co_await async_read(socket, aux_buffer);
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co_await async_read(socket, aux_buffer, adapt(get));
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std::cout
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<< "Before expiration: " << get.has_value() << ", "
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<< *get << "\n";
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// Waits some seconds for the key to expire.
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timer tm{socket.get_executor(), std::chrono::seconds{3}};
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co_await tm.async_wait();
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// Creates and sends the second request, after expiration.
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get.reset(); sr.clear();
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sr.push(command::get, "key");
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sr.push(command::quit);
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co_await async_write(socket, buffer(sr.request()));
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// Reads the response to the second request.
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co_await async_read(socket, aux_buffer, adapt(get));
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co_await async_read(socket, aux_buffer);
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std::cout << "After expiration: " << get.has_value() << "\n";
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} catch (std::exception const& e) {
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std::cerr << e.what() << std::endl;
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}
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}
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int main()
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{
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net::io_context ioc;
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co_spawn(ioc, key_expiration(), net::detached);
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ioc.run();
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}
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/// \example key_expiration.cpp
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