Merge pull request #145 from boostorg/138-use-stdfunction-to-type-erase-the-adapter

Uses std::function to type erase the response adapter

Author: mzimbres

CMakePresets.json

@@ -90,6 +90,23 @@
         "DOXYGEN_OUTPUT_DIRECTORY": "${sourceDir}/build/clang++-13/doc/"
       }
     },
+    {
+      "name": "clang++-14",
+      "generator": "Unix Makefiles",
+      "hidden": false,
+      "inherits": ["cmake-pedantic"],
+      "binaryDir": "${sourceDir}/build/clang++-14",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Debug",
+        "CMAKE_CXX_EXTENSIONS": "OFF",
+        "CMAKE_CXX_FLAGS": "-Wall -Wextra -fsanitize=address",
+        "CMAKE_CXX_COMPILER": "clang++-14",
+        "CMAKE_SHARED_LINKER_FLAGS": "-fsanitize=address",
+        "CMAKE_CXX_STANDARD_REQUIRED": "ON",
+        "PROJECT_BINARY_DIR": "${sourceDir}/build/clang++-14",
+        "DOXYGEN_OUTPUT_DIRECTORY": "${sourceDir}/build/clang++-14/doc/"
+      }
+    },
     {
       "name": "libc++-14-cpp17",
       "generator": "Unix Makefiles",
@@ -143,6 +160,7 @@
      { "name": "g++-11", "configurePreset": "g++-11" },
      { "name": "g++-11-release", "configurePreset": "g++-11-release" },
      { "name": "clang++-13", "configurePreset": "clang++-13" },
+     { "name": "clang++-14", "configurePreset": "clang++-14" },
      { "name": "libc++-14-cpp17", "configurePreset": "libc++-14-cpp17" },
      { "name": "libc++-14-cpp20", "configurePreset": "libc++-14-cpp20" },
      { "name": "clang-tidy", "configurePreset": "clang-tidy" }
@@ -158,6 +176,7 @@
      { "name": "g++-11",          "configurePreset": "g++-11",           "inherits": ["test"] },
      { "name": "g++-11-release",  "configurePreset": "g++-11-release",   "inherits": ["test"] },
      { "name": "clang++-13",      "configurePreset": "clang++-13",       "inherits": ["test"] },
+     { "name": "clang++-14",      "configurePreset": "clang++-14",       "inherits": ["test"] },
      { "name": "libc++-14-cpp17", "configurePreset": "libc++-14-cpp17",  "inherits": ["test"] },
      { "name": "libc++-14-cpp20", "configurePreset": "libc++-14-cpp20",  "inherits": ["test"] },
      { "name": "clang-tidy",      "configurePreset": "clang-tidy",       "inherits": ["test"] }

README.md

@@ -676,6 +676,18 @@ https://lists.boost.org/Archives/boost/2023/01/253944.php.
 
 ### develop (incorporates changes to conform the boost review and more)
 
+* Deprecates the `async_receive` overload that takes a response. Users
+  should now first call `set_receive_response` to avoid contantly seting
+  the same response.
+
+* Uses `std::function` to type erase the response adapter. This change
+  should not influence users in any way but allowed important
+  simplification in the connections internals. This resulted in big
+  performance improvement where one of my benchmark programs passed
+  from 190k/s to 473k/s.
+
+### v1.4.2 (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.

examples/cpp20_chat_room.cpp

@@ -39,15 +39,17 @@ receiver(std::shared_ptr<connection> conn) -> net::awaitable<void>
    request req;
    req.push("SUBSCRIBE", "channel");
 
+   generic_response resp;
+   conn->set_receive_response(resp);
+
    while (conn->will_reconnect()) {
 
       // Subscribe to channels.
       co_await conn->async_exec(req, ignore, net::deferred);
 
       // Loop reading Redis push messages.
-      for (generic_response resp;;) {
-         error_code ec;
-         co_await conn->async_receive(resp, redirect_error(use_awaitable, ec));
+      for (error_code ec;;) {
+         co_await conn->async_receive(redirect_error(use_awaitable, ec));
          if (ec)
             break; // Connection lost, break so we can reconnect to channels.
          std::cout

examples/cpp20_subscriber.cpp

@@ -52,16 +52,18 @@ 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, net::deferred);
 
       // Loop reading Redis pushs messages.
-      for (generic_response resp;;) {
-         error_code ec;
-         co_await conn->async_receive(resp, net::redirect_error(net::use_awaitable, ec));
+      for (error_code ec;;) {
+         co_await conn->async_receive(net::redirect_error(net::use_awaitable, ec));
          if (ec)
             break; // Connection lost, break so we can reconnect to channels.
          std::cout

examples/main.cpp

@@ -30,7 +30,7 @@ auto main(int argc, char * argv[]) -> int
       }
 
       net::io_context ioc;
-      net::co_spawn(ioc, std::move(co_main(cfg)), [](std::exception_ptr p) {
+      net::co_spawn(ioc, co_main(cfg), [](std::exception_ptr p) {
          if (p)
             std::rethrow_exception(p);
       });

include/boost/redis/connection.hpp

@@ -184,10 +184,15 @@ class basic_connection {
     *  Where the second parameter is the size of the push received in
     *  bytes.
     */
+   template <class CompletionToken = asio::default_completion_token_t<executor_type>>
+   auto async_receive(CompletionToken token = CompletionToken{})
+      { return impl_.async_receive(std::move(token)); }
+
    template <
       class Response = ignore_t,
       class CompletionToken = asio::default_completion_token_t<executor_type>
    >
+   [[deprecated("Set the response with set_receive_response and use the other overload.")]]
    auto
    async_receive(
       Response& response,
@@ -282,6 +287,11 @@ class basic_connection {
    auto const& next_layer() const noexcept
       { return impl_.next_layer(); }
 
+   /// Sets the response object of `async_receive` operations.
+   template <class Response>
+   void set_receive_response(Response& response)
+      { impl_.set_receive_response(response); }
+
 private:
    using timer_type =
       asio::basic_waitable_timer<
@@ -342,11 +352,17 @@ class connection {
 
    /// Calls `boost::redis::basic_connection::async_receive`.
    template <class Response, class CompletionToken>
+   [[deprecated("Set the response with set_receive_response and use the other overload.")]]
    auto async_receive(Response& response, CompletionToken token)
    {
       return impl_.async_receive(response, std::move(token));
    }
 
+   /// Calls `boost::redis::basic_connection::async_receive`.
+   template <class CompletionToken>
+   auto async_receive(CompletionToken token)
+      { return impl_.async_receive(std::move(token)); }
+
    /// Calls `boost::redis::basic_connection::async_exec`.
    template <class Response, class CompletionToken>
    auto async_exec(request const& req, Response& resp, CompletionToken token)
@@ -373,6 +389,11 @@ class connection {
    void reset_stream()
       { impl_.reset_stream();}
 
+   /// Sets the response object of `async_receive` operations.
+   template <class Response>
+   void set_receive_response(Response& response)
+      { impl_.set_receive_response(response); }
+
 private:
    void
    async_run_impl(