Merge pull request #134 from boostorg/123-automatically-select-databa…

…se-after-hello

123 automatically select database after hello

README.md

@@ -676,6 +676,15 @@ https://lists.boost.org/Archives/boost/2023/01/253944.php.
 
 ### develop (incorporates changes to conform the boost review and more)
 
+* Adds `boost::redis::config::database_index` to make it possible to
+ choose a database before starting running commands e.g. after an
+ automatic reconnection.
+
+* Massive performance improvement. One of my tests went from
+ 140k req/s to 390k/s. This was possible after a parser
+ simplification that reduced the number of reschedules and buffer
+ rotations.
+
 * Adds Redis stream example.
 
 * Renames the project to Boost.Redis and moves the code into namespace

examples/cpp20_streams.cpp

@@ -41,11 +41,11 @@ auto stream_reader(std::shared_ptr<connection> conn) -> net::awaitable<void>
  req.push("XREAD", "BLOCK", "0", "STREAMS", "test-topic", stream_id);
  co_await conn->async_exec(req, resp, net::deferred);
 
- // std::cout << "Response: ";
- // for (int i = 0; i < resp->value().size(); ++i) {
- //  std::cout << resp->value().at(i).value << ", ";
- // }
- // std::cout << std::endl;
+ //std::cout << "Response: ";
+ //for (auto i = 0UL; i < resp->size(); ++i) {
+ // std::cout << resp->at(i).value << ", ";
+ //}
+ //std::cout << std::endl;
 
  // The following approach was taken in order to be able to
  // deal with the responses, as generated by redis in the case

include/boost/redis/config.hpp

@@ -9,6 +9,7 @@
 
 #include <string>
 #include <chrono>
+#include <optional>
 
 namespace boost::redis
 {
@@ -48,6 +49,9 @@ struct config {
  /// Client name parameter of the [HELLO](https://redis.io/commands/hello/) command.
  std::string clientname = "Boost.Redis";
 
+ /// Database that will be passed to the [SELECT](https://redis.io/commands/hello/) command.
+ std::optional<int> database_index = 0;
+
  /// Message used by the health-checker in `boost::redis::connection::async_run`.
  std::string health_check_id = "Boost.Redis";
 

include/boost/redis/detail/runner.hpp

@@ -231,6 +231,9 @@ class runner {
  hello_req_.push("HELLO", "3", "AUTH", cfg_.username, cfg_.password);
  else
  hello_req_.push("HELLO", "3", "SETNAME", cfg_.clientname);
+
+ if (cfg_.database_index)
+ hello_req_.push("SELECT", cfg_.database_index.value());
  }
 
  resolver_type resv_;

tests/test_conn_exec.cpp

@@ -20,8 +20,10 @@ namespace net = boost::asio;
 using boost::redis::connection;
 using boost::redis::request;
 using boost::redis::response;
+using boost::redis::generic_response;
 using boost::redis::ignore;
 using boost::redis::operation;
+using boost::redis::config;
 
 // Sends three requests where one of them has a hello with a priority
 // set, which means it should be executed first.
@@ -117,3 +119,38 @@ BOOST_AUTO_TEST_CASE(cancel_request_if_not_connected)
 
  ioc.run();
 }
+
+BOOST_AUTO_TEST_CASE(correct_database)
+{
+ config cfg;
+ cfg.database_index = 2;
+
+ net::io_context ioc;
+
+ auto conn = std::make_shared<connection>(ioc);
+
+ request req;
+ req.push("CLIENT", "LIST");
+
+ generic_response resp;
+
+ conn->async_exec(req, resp, [&](auto ec, auto n){
+ BOOST_TEST(!ec);
+ std::clog << "async_exec has completed: " << n << std::endl;
+ conn->cancel();
+ });
+
+ conn->async_run(cfg, {}, [](auto){
+ std::clog << "async_run has exited." << std::endl;
+ });
+
+ ioc.run();
+
+ assert(!resp.value().empty());
+ auto const& value = resp.value().front().value;
+ auto const pos = value.find("db=");
+ auto const index_str = value.substr(pos + 3, 1);
+ auto const index = std::stoi(index_str);
+ BOOST_CHECK_EQUAL(cfg.database_index.value(), index);
+}
+