update condy dependency

.github/workflows/ci-latest-kernel.yml

@@ -99,6 +99,7 @@ jobs:
               -DUBLKCPP_BUILD_TESTS=ON \
               -DUBLKCPP_BUILD_UBLKCTL=ON \
               -DUBLKCPP_TESTS_STATIC_LINK=ON \
+              -DCONDY_LINK_STDEXEC=ON \
               -DCMAKE_C_COMPILER=clang \
               -DCMAKE_CXX_COMPILER=clang++ \
               -DCMAKE_BUILD_TYPE=Release

.github/workflows/ci-main.yml

@@ -54,7 +54,7 @@ jobs:
               -DUBLKCPP_BUILD_TESTS=ON \
               -DUBLKCPP_BUILD_UBLKCTL=ON \
               -DUBLKCPP_BUILD_EXAMPLES=ON \
-              -DUBLKCPP_EXECUTION_BACKEND=stdexec \
+              -DCONDY_LINK_STDEXEC=ON \
               $SANITIZER_FLAG \
               -DCMAKE_C_COMPILER=${{matrix.compiler.cc}} \
               -DCMAKE_CXX_COMPILER=${{matrix.compiler.cxx}} \

.github/workflows/ci-static-check.yml

@@ -39,6 +39,7 @@ jobs:
           cmake -B ${{github.workspace}}/build \
               -DUBLKCPP_BUILD_TESTS=ON \
               -DUBLKCPP_BUILD_UBLKCTL=ON \
+              -DCONDY_LINK_STDEXEC=ON \
               -DCMAKE_C_COMPILER=clang \
               -DCMAKE_CXX_COMPILER=clang++ \
               -DCMAKE_BUILD_TYPE=Debug \

.github/workflows/ci-toolchain.yml

@@ -20,7 +20,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        backend: [ "stdexec", "beman" ]
+        backend: [ STDEXEC, BEMAN ]
         compiler:
           - { cc: gcc, cxx: g++ }
           - { cc: clang, cxx: clang++ }
@@ -49,7 +49,7 @@ jobs:
               -DUBLKCPP_BUILD_TESTS=ON \
               -DUBLKCPP_BUILD_UBLKCTL=ON \
               -DUBLKCPP_BUILD_EXAMPLES=ON \
-              -DUBLKCPP_EXECUTION_BACKEND=${{ matrix.backend }} \
+              -DCONDY_LINK_${{ matrix.backend }}=ON \
               -DCMAKE_C_COMPILER=${{matrix.compiler.cc}} \
               -DCMAKE_CXX_COMPILER=${{matrix.compiler.cxx}} \
               -DCMAKE_BUILD_TYPE=Debug

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.13)
+cmake_minimum_required(VERSION 3.24)
 
 # Version is defined once in the version header.
 set(UBLKCPP_VERSION_HEADER include/ublk/version.hpp)
@@ -20,8 +20,6 @@ option(UBLKCPP_USE_URING_CMD128 "Use IORING_OP_URING_CMD128 for control commands
 option(UBLKCPP_TESTS_STATIC_LINK "Use static linking for tests" OFF)
 option(UBLKCPP_TESTS_ASAN "Enable address and undefined behavior sanitizers for tests" OFF)
 option(UBLKCPP_TESTS_TSAN "Enable thread sanitizer for tests" OFF)
-set(UBLKCPP_EXECUTION_BACKEND "stdexec" CACHE STRING
-    "std::execution implementation used via Condy: stdexec (default) or beman")
 
 include(FetchContent)
 
@@ -47,23 +45,11 @@ FetchContent_Declare(
 
 add_library(ublkcpp INTERFACE)
 target_include_directories(ublkcpp INTERFACE include)
-target_compile_features(ublkcpp INTERFACE cxx_std_23) # TODO: cxx_std_26
+target_compile_features(ublkcpp INTERFACE cxx_std_20)
 if(UBLKCPP_USE_URING_CMD128)
     target_compile_definitions(ublkcpp INTERFACE UBLKCPP_USE_URING_CMD128)
 endif()
 
-if(UBLKCPP_EXECUTION_BACKEND STREQUAL "beman")
-    set(CONDY_ENABLE_STDEXEC OFF)
-    set(CONDY_ENABLE_BEMAN ON)
-elseif(UBLKCPP_EXECUTION_BACKEND STREQUAL "stdexec")
-    set(CONDY_ENABLE_STDEXEC ON)
-    set(CONDY_ENABLE_BEMAN OFF)
-else()
-    message(FATAL_ERROR
-        "UBLKCPP_EXECUTION_BACKEND must be 'stdexec' or 'beman', got '"
-        "${UBLKCPP_EXECUTION_BACKEND}'")
-endif()
-message(STATUS "ublkcpp: execution backend: ${UBLKCPP_EXECUTION_BACKEND}")
 add_subdirectory(third_party/condy)
 target_link_libraries(ublkcpp INTERFACE condy)
 

README.md

@@ -1,6 +1,6 @@
 # ublk-cpp
 
-![C++](https://img.shields.io/badge/C++-26-blue)
+![C++](https://img.shields.io/badge/C++-20-blue)
 ![License](https://img.shields.io/github/license/condy-cpp/ublk-cpp)
 ![Release](https://img.shields.io/github/v/release/condy-cpp/ublk-cpp)
 ![Stars](https://img.shields.io/github/stars/condy-cpp/ublk-cpp?style=social)
@@ -10,21 +10,17 @@
 ![CI (Static Check)](https://github.com/condy-cpp/ublk-cpp/actions/workflows/ci-static-check.yml/badge.svg?branch=master)
 ![Deploy Docs](https://github.com/condy-cpp/ublk-cpp/actions/workflows/deploy-docs.yml/badge.svg?branch=master)
 
-ublk-cpp is a C++ library for writing [ublk servers](https://docs.kernel.org/block/ublk.html), targeting the C++26 `std::execution` sender model:
+ublk-cpp is a C++ library for writing [ublk servers](https://docs.kernel.org/block/ublk.html), built on the `std::execution` sender model:
 
 - **Comprehensive ublk Support**
   Full coverage of the ublk userspace interface — device lifecycle management, per-queue I/O loops, and advanced features such as user recovery and shm buffer registration.
 
 - **Full io_uring Ecosystem**
   Built on top of [Condy](https://github.com/condy-cpp/condy), all io_uring operations can be used directly inside your ublk server.
 
-- **C++26 Sender Model**
+- **Sender Model**
   The API is built on `std::execution` senders — composable with standard algorithms and interoperable with any asynchronous driver.
 
-> [!NOTE]
-> This repository is experimental and will not reach a stable state until
-> `std::execution` (C++26) is finalized.
-
 ## Documentation
 
 - **[Online Docs (GitHub Pages)](https://condy-cpp.github.io/ublk-cpp/)**

bin/ublkctl.cpp

@@ -11,16 +11,17 @@
 #include <cstdlib>
 #include <fcntl.h>
 #include <filesystem>
+#include <format>
 #include <iostream>
-#include <print>
 #include <sched.h>
+#include <stdexcept>
 #include <string>
 #include <ublk.hpp>
 #include <unistd.h>
 #include <utility>
 #include <variant>
 
-namespace ex = condy::detail::ex;
+namespace ex = ublk::detail::ex;
 
 struct AddCmd {
     uint32_t dev_id = -1;
@@ -127,18 +128,20 @@ std::string flags_str(uint64_t flags) noexcept {
 
 void dump_dev_info(uint32_t dev_id, const ublksrv_ctrl_dev_info &info,
                    const ublk_params &params) {
-    std::println("dev id {}: nr_hw_queues {} queue_depth {} block size {} "
-                 "dev_capacity {}",
-                 dev_id, info.nr_hw_queues, info.queue_depth,
-                 1U << params.basic.logical_bs_shift, params.basic.dev_sectors);
-    std::println("\tmax rq size {} daemon pid {} state {}",
-                 info.max_io_buf_bytes, info.ublksrv_pid,
-                 state_str(info.state));
-    std::println("\tflags 0x{:x} [{}]", info.flags, flags_str(info.flags));
-    std::println("\tublkc: {}:{} ublkb: {}:{} owner: {}:{}",
-                 params.devt.char_major, params.devt.char_minor,
-                 params.devt.disk_major, params.devt.disk_minor, info.owner_uid,
-                 info.owner_gid);
+    std::cout << std::format("dev id {}: nr_hw_queues {} queue_depth {} block "
+                             "size {} dev_capacity {}\n",
+                             dev_id, info.nr_hw_queues, info.queue_depth,
+                             1U << params.basic.logical_bs_shift,
+                             params.basic.dev_sectors);
+    std::cout << std::format("\tmax rq size {} daemon pid {} state {}\n",
+                             info.max_io_buf_bytes, info.ublksrv_pid,
+                             state_str(info.state));
+    std::cout << std::format("\tflags 0x{:x} [{}]\n", info.flags,
+                             flags_str(info.flags));
+    std::cout << std::format("\tublkc: {}:{} ublkb: {}:{} owner: {}:{}\n",
+                             params.devt.char_major, params.devt.char_minor,
+                             params.devt.disk_major, params.devt.disk_minor,
+                             info.owner_uid, info.owner_gid);
 }
 
 std::string cpu_str(const cpu_set_t &cpuset) noexcept {
@@ -171,7 +174,8 @@ ex::task<void> dump_queue_affinity(int ctrl_fd,
     for (uint16_t q_id = 0; q_id < info.nr_hw_queues; q_id++) {
         cpu_set_t cpuset;
         co_await ublk::get_queue_affinity(ctrl_fd, info.dev_id, q_id, &cpuset);
-        std::println("\tqueue {}: affinity({})", q_id, cpu_str(cpuset));
+        std::cout << std::format("\tqueue {}: affinity({})\n", q_id,
+                                 cpu_str(cpuset));
     }
 }
 
@@ -253,10 +257,11 @@ ex::task<void> run_cmd(int ctrl_fd, const FeaturesCmd &) {
     uint64_t features = 0;
     co_await ublk::get_features(ctrl_fd, &features);
 
-    std::println("ublk_drv features: 0x{:x}", features);
+    std::cout << std::format("ublk_drv features: 0x{:x}\n", features);
     for (const auto &e : FLAG_TABLE) {
         if (features & e.flag)
-            std::println("\t{:<20s}: 0x{:x}", e.short_name, e.flag);
+            std::cout << std::format("\t{:<20s}: 0x{:x}\n", e.short_name,
+                                     e.flag);
     }
 }
 
@@ -367,7 +372,7 @@ Cmd parse_args(int argc, char *argv[]) {
     } else if (app.got_subcommand("quiesce")) {
         return quiesce_opts;
     } else {
-        std::unreachable();
+        throw std::runtime_error("unhandled subcommand");
     }
 }
 
@@ -391,10 +396,10 @@ int main(int argc, char *argv[]) noexcept(false) {
             std::visit([&](const auto &c) { return run_cmd(ctrl_fd, c); },
                        cmd)));
     } catch (const std::system_error &e) {
-        std::println(std::cerr, "ublkctl: {}", e.what());
+        std::cerr << std::format("ublkctl: {}\n", e.what());
         return e.code().value();
     } catch (const std::exception &e) {
-        std::println(std::cerr, "ublkctl: {}", e.what());
+        std::cerr << std::format("ublkctl: {}\n", e.what());
         return 1;
     }
     return 0;

docs/Doxyfile.in

@@ -54,7 +54,7 @@ PROJECT_NUMBER         = @UBLKCPP_VERSION_STRING@
 # for a project that appears at the top of each page and should give viewers a
 # quick idea about the purpose of the project. Keep the description short.
 
-PROJECT_BRIEF          = A ublk library targeting C++26 std::execution.
+PROJECT_BRIEF          = A ublk library for std::execution.
 
 # With the PROJECT_LOGO tag one can specify a logo or an icon that is included
 # in the documentation. The maximum height of the logo should not exceed 55

docs/build.md

@@ -3,7 +3,7 @@
 @brief How to build and integrate ublk-cpp in your project.
 
 > [!NOTE]
-> ublk-cpp currently depends on condy's **experimental execution integration**, which can be backed by either **stdexec** (default) or **beman/execution**. Once `std::execution` is finalized in C++26, it will migrate to the standard library implementation.
+> ublk-cpp requires condy with `std::execution` support. Condy uses the standard library implementation when available, or a fetched backend ([stdexec](https://github.com/NVIDIA/stdexec) or [beman/execution](https://github.com/bemanproject/execution)) enabled through condy's `CONDY_LINK_STDEXEC` / `CONDY_LINK_BEMAN` options.
 
 ## Using ublk-cpp as a Submodule
 
@@ -42,7 +42,7 @@ target_link_libraries(my_app PRIVATE ublkcpp)
 
 Condy fetches and **statically links liburing** by default (`CONDY_LINK_LIBURING=ON`). To use the liburing installed on your system instead, configure with `CONDY_LINK_LIBURING=OFF`.
 
-ublk-cpp currently also fetches and depends on **[stdexec](https://github.com/NVIDIA/stdexec)**, or **[beman/execution](https://github.com/bemanproject/execution)** when enabled via the `UBLKCPP_EXECUTION_BACKEND` option. Once `std::execution` is finalized in C++26, this dependency is expected to be replaced by the standard library implementation.
+ublk-cpp requires condy with `std::execution` support. When the standard library provides it, condy detects it automatically. Otherwise enable a fetched backend with `CONDY_LINK_STDEXEC=ON` ([stdexec](https://github.com/NVIDIA/stdexec)) or `CONDY_LINK_BEMAN=ON` ([beman/execution](https://github.com/bemanproject/execution)).
 
 ## Building
 
@@ -55,15 +55,13 @@ ublk-cpp provides CMake options to build tests, the `ublkctl` tool, examples, an
 | `UBLKCPP_BUILD_EXAMPLES` | Build examples | OFF |
 | `UBLKCPP_BUILD_DOCS` | Build Doxygen documentation | OFF |
 | `UBLKCPP_USE_URING_CMD128` | Use `IORING_OP_URING_CMD128` for control commands | ON |
-| `UBLKCPP_TESTS_STATIC_LINK` | Use static linking for tests | OFF |
-| `UBLKCPP_TESTS_ASAN` | Enable ASan/UBSan for tests | OFF |
-| `UBLKCPP_EXECUTION_BACKEND` | `std::execution` implementation used via Condy: `stdexec` or `beman` | `stdexec` |
 
 ```bash
 cmake -B build -S . \
     -DUBLKCPP_BUILD_TESTS=ON \
     -DUBLKCPP_BUILD_UBLKCTL=ON \
     -DUBLKCPP_BUILD_EXAMPLES=ON \
+    -DCONDY_LINK_STDEXEC=ON \
     -DCMAKE_BUILD_TYPE=Release
 cmake --build build -j$(nproc)
 ```

docs/guide.md

@@ -9,6 +9,7 @@ ublk is a kernel framework for implementing block device drivers in userspace. I
 The runtime is represented by `condy::Runtime`, and a scheduler object can be obtained via `condy::get_scheduler()`. All interfaces provided by ublk-cpp are required to run on that scheduler.
 
 ```cpp
+namespace ex = std::execution; // or stdexec / beman::execution
 // sqe128 is required for ublk control cmd
 condy::Runtime runtime(condy::RuntimeOptions().enable_sqe128());
 std::jthread loop([&]() { runtime.run(); });
@@ -180,15 +181,16 @@ Then run `ublk::daemon::run()` and `ublk::daemon::start()` concurrently. After `
 ```cpp
 ex::task<void> wait_signal(int ctrl_fd, int signal_fd, uint32_t dev_id,
                            ex::inplace_stop_source &source) {
-    std::println("ublk-nop: ublk device {} is running...", dev_id);
+    std::cout << std::format("ublk-nop: ublk device {} is running...\n",
+                             dev_id);
     auto parent_token = co_await ex::read_env(ex::get_stop_token);
     ex::inplace_stop_callback cb{parent_token,
-                                 [&] noexcept { source.request_stop(); }};
+                                 [&]() noexcept { source.request_stop(); }};
     signalfd_siginfo si;
     co_await (condy::async_read(signal_fd, condy::buffer(&si, sizeof(si)), 0) |
               ex::write_env(ex::prop{ex::get_stop_token, source.get_token()}));
-    std::println("ublk-nop: received signal {}, shutting down...",
-                 si.ssi_signo);
+    std::cout << std::format(
+        "ublk-nop: received signal {}, shutting down...\n", si.ssi_signo);
     co_await ublk::stop_dev(ctrl_fd, dev_id);
 }
 // ...