cpp20_containers.cpp

/* Copyright (c) 2018-2025 Marcelo Zimbres Silva (mzimbres@gmail.com)
 *
 * Distributed under the Boost Software License, Version 1.0. (See
 * accompanying file LICENSE.txt)
 */
 
#include <boost/redis/connection.hpp>
#include <boost/asio/detached.hpp>
#include <boost/asio/co_spawn.hpp>
#include <map>
#include <vector>
#include <iostream>
 
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
 
namespace asio = boost::asio;
using boost::redis::request;
using boost::redis::response;
using boost::redis::ignore_t;
using boost::redis::ignore;
using boost::redis::config;
using boost::redis::connection;
using boost::asio::awaitable;
using boost::asio::detached;
using boost::asio::consign;
 
template<class T>
std::ostream& operator<<(std::ostream& os, std::optional<T> const& opt)
{
    if (opt.has_value())
        std::cout << opt.value();
    else
        std::cout << "null";
 
    return os;
}
 
void print(std::map<std::string, std::string> const& cont)
{
   for (auto const& e: cont)
      std::cout << e.first << ": " << e.second << "\n";
}
 
template <class T>
void print(std::vector<T> const& cont)
{
   for (auto const& e: cont) std::cout << e << " ";
   std::cout << "\n";
}
 
// Stores the content of some STL containers in Redis.
auto store(std::shared_ptr<connection> conn) -> awaitable<void>
{
   std::vector<int> vec
      {1, 2, 3, 4, 5, 6};
 
   std::map<std::string, std::string> map
      {{"key1", "value1"}, {"key2", "value2"}, {"key3", "value3"}};
 
   request req;
   req.push_range("RPUSH", "rpush-key", vec);
   req.push_range("HSET", "hset-key", map);
   req.push("SET", "key", "value");
 
   co_await conn->async_exec(req, ignore);
}
 
auto hgetall(std::shared_ptr<connection> conn) -> awaitable<void>
{
   // A request contains multiple commands.
   request req;
   req.push("HGETALL", "hset-key");
 
   // Responses as tuple elements.
   response<std::map<std::string, std::string>> resp;
 
   // Executes the request and reads the response.
   co_await conn->async_exec(req, resp);
 
   print(std::get<0>(resp).value());
}
 
auto mget(std::shared_ptr<connection> conn) -> awaitable<void>
{
   // A request contains multiple commands.
   request req;
   req.push("MGET", "key", "non-existing-key");
 
   // Responses as tuple elements.
   response<std::vector<std::optional<std::string>>> resp;
 
   // Executes the request and reads the response.
   co_await conn->async_exec(req, resp);
 
   print(std::get<0>(resp).value());
}
 
// Retrieves in a transaction.
auto transaction(std::shared_ptr<connection> conn) -> awaitable<void>
{
   request req;
   req.push("MULTI");
   req.push("LRANGE", "rpush-key", 0, -1); // Retrieves
   req.push("HGETALL", "hset-key"); // Retrieves
   req.push("MGET", "key", "non-existing-key");
   req.push("EXEC");
 
   response<
      ignore_t, // multi
      ignore_t, // lrange
      ignore_t, // hgetall
      ignore_t, // mget
      response<
         std::optional<std::vector<int>>,
         std::optional<std::map<std::string, std::string>>,
         std::optional<std::vector<std::optional<std::string>>>
      > // exec
   > resp;
 
   co_await conn->async_exec(req, resp);
 
   print(std::get<0>(std::get<4>(resp).value()).value().value());
   print(std::get<1>(std::get<4>(resp).value()).value().value());
   print(std::get<2>(std::get<4>(resp).value()).value().value());
}
 
// Called from the main function (see main.cpp)
awaitable<void> co_main(config cfg)
{
   auto conn = std::make_shared<connection>(co_await asio::this_coro::executor);
   conn->async_run(cfg, {}, consign(detached, conn));
 
   co_await store(conn);
   co_await transaction(conn);
   co_await hgetall(conn);
   co_await mget(conn);
   conn->cancel();
}
 
#endif // defined(BOOST_ASIO_HAS_CO_AWAIT)