Boost.Redis is a high-level Redis client library built on top of Boost.Asio that implements the Redis protocol RESP3.
Full documentation is here.
The requirements for using Boost.Redis are:
- Boost 1.84 or higher. Boost.Redis is included in Boost installations since Boost 1.84.
- C++17 or higher. Supported compilers include gcc 11 and later, clang 11 and later, and Visual Studio 16 (2019) and later.
- Redis 6 or higher (must support RESP3).
- OpenSSL.
The documentation assumes basic-level knowledge about Redis and Boost.Asio.
To use the library it is necessary to include the following:
#include <boost/redis/src.hpp>in exactly one source file in your applications. Otherwise, the library is header-only.
Boost.Redis unconditionally requires OpenSSL. Targets using Boost.Redis need to link to the OpenSSL libraries.
The code below uses a short-lived connection to ping a Redis server:
#include <boost/redis/connection.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/consign.hpp>
#include <boost/asio/detached.hpp>
#include <iostream>
namespace net = boost::asio;
using boost::redis::request;
using boost::redis::response;
using boost::redis::config;
using boost::redis::connection;
auto co_main(config const& cfg) -> net::awaitable<void>
{
auto conn = std::make_shared<connection>(co_await net::this_coro::executor);
conn->async_run(cfg, {}, net::consign(net::detached, conn));
// A request containing only a ping command.
request req;
req.push("PING", "Hello world");
// Response object.
response<std::string> resp;
// Executes the request.
co_await conn->async_exec(req, resp);
conn->cancel();
std::cout << "PING: " << std::get<0>(resp).value() << std::endl;
}The roles played by the async_run and async_exec functions are:
connection::async_exec: executes the commands contained in the request and stores the individual responses in the response object. Can be called from multiple places in your code concurrently.connection::async_run: keeps the connection healthy. It takes care of hostname resolution, session establishment, health-checks, reconnection and coordination of low-level read and write operations. It should be called only once per connection, regardless of the number of requests to execute.
Redis servers can also send a variety of pushes to the client. Some of them are:
The connection class supports server pushes by means of the
connection::async_receive function, which can be
called in the same connection that is being used to execute commands.
The coroutine below shows how to use it:
auto
receiver(std::shared_ptr<connection> conn) -> net::awaitable<void>
{
request req;
req.push("SUBSCRIBE", "channel");
generic_response resp;
conn->set_receive_response(resp);
// Loop while reconnection is enabled
while (conn->will_reconnect()) {
// Reconnect to channels.
co_await conn->async_exec(req, ignore);
// Loop reading Redis pushes.
for (;;) {
error_code ec;
co_await conn->async_receive(resp, net::redirect_error(net::use_awaitable, ec));
if (ec)
break; // Connection lost, break so we can reconnect to channels.
// Use the response resp in some way and then clear it.
...
consume_one(resp);
}
}
}Full documentation is here.