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git-subtree-split: 57eee82fa5
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Roland Conybeare 2025-05-10 18:38:12 -05:00
commit 06981d4c29
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xo-subsys/.github/workflows/cmake-single-platform.yml vendored Normal file
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# This starter workflow is for a CMake project running on a single platform. There is a different starter workflow if you need cross-platform coverage.
# See: https://github.com/actions/starter-workflows/blob/main/ci/cmake-multi-platform.yml
name: CMake on a single platform
on:
push:
branches: [ "main" ]
pull_request:
branches: [ "main" ]
env:
# Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
BUILD_TYPE: Release
jobs:
build:
# The CMake configure and build commands are platform agnostic and should work equally well on Windows or Mac.
# You can convert this to a matrix build if you need cross-platform coverage.
# See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
# ----------------------------------------------------------------
- name: Clone xo-cmake
uses: actions/checkout@v3
with:
repository: Rconybea/xo-cmake
path: repo/xo-cmake
- name: Configure xo-cmake
run: cmake -B ${{github.workspace}}/build_xo-cmake -DCMAKE_INSTALL_PREFIX=${{github.workspace}}/local repo/xo-cmake
- name: Build xo-cmake (trivial)
run: cmake --build ${{github.workspace}}/build_xo-cmake --config ${{env.BUILD_TYPE}}
- name: Install xo-cmake
run: cmake --install ${{github.workspace}}/build_xo-cmake
# ----------------------------------------------------------------
- name: Configure self (subsys)
# Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
# See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
run: cmake -B ${{github.workspace}}/build -DCMAKE_MODULE_PATH=${{github.workspace}}/local/share/cmake -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}}
- name: Build self (subsys)
# Build your program with the given configuration
run: cmake --build ${{github.workspace}}/build --config ${{env.BUILD_TYPE}}
- name: Test self (subsys)
working-directory: ${{github.workspace}}/build
# Execute tests defined by the CMake configuration.
# See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more detail
run: ctest -C ${{env.BUILD_TYPE}}

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# emacs workspace config
.projectile
# symlink to ${mybuilddirectory}/compile_commands.json for LSP
compile_commands.json
# LSP keeps state here
.cache
# typical build directories
.build*

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xo-subsys/CMakeLists.txt Normal file
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# xo-subsys/CMakeLists.txt
cmake_minimum_required(VERSION 3.10)
project(subsys VERSION 0.1)
include(GNUInstallDirs)
include(cmake/xo-bootstrap-macros.cmake)
xo_cxx_toplevel_options2()
# ----------------------------------------------------------------
# cmake -DCMAKE_BUILD_TYPE=coverage
xo_toplevel_coverage_config2()
# ----------------------------------------------------------------
# cmake -DCMAKE_BUILD_TYPE=debug
xo_toplevel_debug_config2()
#set(XO_PROJECT_NAME subsys)
# ----------------------------------------------------------------
# installing header-only library
set(SELF_LIB subsys)
xo_add_headeronly_library(${SELF_LIB})
xo_install_library4(${SELF_LIB} ${PROJECT_NAME}Targets)
#add_library(subsys INTERFACE)
#xo_include_headeronly_options2(subsys)
#xo_install_library2(subsys)
# ----------------------------------------------------------------
# provide find_package() support
xo_export_cmake_config(${PROJECT_NAME} ${PROJECT_VERSION} ${PROJECT_NAME}Targets)
# end CMakeLists.txt

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xo-subsys/README.md Normal file
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# plugin initialization support
subsys is a small header-only library providing support for plugin initialization
## Features
- provide application control of initialization order across c++ libraries
- circumvents the 'static order initialization fiasco'
- ensure initialization code runs exactly once if subsystem is linked
- enforce initialization order constraints
- defend against static linker stripping essential initialization code
- designed to work cleanly for libraries integrating into existing executable like python, java runtime, ..
- initialization state browseable at runtime
## Getting Started
### build + install `indentlog` dependency
see [github/rconybea/indentlog](https://github.com/Rconybea/indentlog)
### copy `subsys` repository locally
```
$ git clone git@github.com:rconybea/subsys.git
$ ls -d subsys
subsys
```
### build + install
```
$ cd subsys
$ mkdir build
$ cd build
$ INSTALL_PREFIX=/usr/local # or wherever you prefer
$ cmake -DCMAKE_MODULE_PATH=${INSTALL_PREFIX}/share/cmake -DCMAKE_PREFIX_PATH=${INSTALL_PREFIX} -DCMAKE_INSTALL_PREFIX=${INSTALL_PREFIX} ..
$ make
$ make install
```
`CMAKE_PREFIX_PATH` should point to prefix where `indentlog` is installed
alternatively, if you're a nix user:
```
$ git clone git@github.com:rconybea/xo-nix.git
$ ls -d xo-nix
xo-nix
$ cd xo-nix
$ nix-build -A subsys
```
### build for unit test coverage
```
$ cd subsys
$ mkdir ccov
$ cd ccov
$ cmake -DCMAKE_PREFIX_PATH=${INSTALL_PREFIX} -DCODE_COVERAGE=ON -DCMAKE_BUILD_TYPE=Debug ..
```
## Examples
### 1
```
// initialization code in .hpp for a subsystem foo, that relies on related subsystem bar
#include "subsys/Subsystem.hpp"
enum S_foo_tag {}; /* tag to represent initialization of subsystem foo */
template<>
struct InitSubsys<S_foo_tag> {
static void init() {
// plugin initialization for subsystem foo
}
static InitEvidence require() {
InitEvidence retval;
// demand initialization of dependent subsystem bar,
// before initialization subsystem foo
//
retval ^= InitSubsys<S_bar_tag>::require();
// initialization of this subsystem foo
retval ^= Subsystem::provide<S_foo_tag>("foo", &init);
return retval;
}
};
```
```
// in application code that relies on foo (perhaps along with other subsystems),
// for example in a pybind11 module:
//
PYBIND11_MODULE(pyfoo, m) {
// include foo in initialization set
InitSubsys<S_foo_tag>::require();
// ensure foo + dependencies are initialized
Subsystem::initialize_all();
...
}
```

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xo-subsys/cmake/subsysConfig.cmake.in Normal file
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@PACKAGE_INIT@
include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
check_required_components("@PROJECT_NAME@")

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xo-subsys/cmake/xo-bootstrap-macros.cmake Normal file
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# ----------------------------------------------------------------
# for example:
# $ PREFIX=/usr/local # for example
# $ cmake -DCMAKE_MODULE_PATH=prefix -DCMAKE_INSTALL_PREFIX=$PREFIX -B .build
#
# will get
# CMAKE_MODULE_PATH
# from xo-cmake-config --cmake-module-path
#
# and expect .cmake macros in
# CMAKE_MODULE_PATH/xo_macros/xo_cxx.cmake
# ----------------------------------------------------------------
find_program(XO_CMAKE_CONFIG_EXECUTABLE NAMES xo-cmake-config REQUIRED)
if ("${XO_CMAKE_CONFIG_EXECUTABLE}" STREQUAL "XO_CMAKE_CONFIG_EXECUTABLE-NOT_FOUND")
message(FATAL "could not find xo-cmake-config executable")
endif()
message(STATUS "XO_CMAKE_CONFIG_EXECUTABLE=${XO_CMAKE_CONFIG_EXECUTABLE}")
if (NOT XO_SUBMODULE_BUILD)
if (("${CMAKE_MODULE_PATH}" STREQUAL "") OR ("${CMAKE_MODULE_PATH}" STREQUAL prefix))
# default to typical install location for xo-project-macros
execute_process(COMMAND ${XO_CMAKE_CONFIG_EXECUTABLE} --cmake-module-path OUTPUT_VARIABLE CMAKE_MODULE_PATH)
message(STATUS "CMAKE_MODULE_PATH=${CMAKE_MODULE_PATH}")
endif()
endif()
# needs to have been installed somewhere on CMAKE_MODULE_PATH,
# (e.g. from xo-cmake with the same value for CMAKE_INSTALL_PREFIX)
#
include(xo_macros/xo_cxx)
xo_cxx_bootstrap_message()

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xo-subsys/include/xo/subsys/Subsystem.hpp Normal file
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/* file Subsystem.hpp
*
* author: Roland Conybeare, Aug 2022
*/
#pragma once
#include "xo/indentlog/scope.hpp"
#include <iostream>
#include <functional>
#include <list>
#include <string_view>
#include <cstddef>
/* e.g. XO_SUBSYSTEM_TAG(simulator) => xo::S_simulator_tag */
#define XO_SUBSYSTEM_TAG(subsys_name) xo::S_ ## subsys_name ## _tag
/* e.g. XO_SUBSYSTEM_REQUIRE(simulator) =>
* xo::InitSubsys<xo::S_simulator_tag>::require()
*/
#define XO_SUBSYSTEM_REQUIRE(subsys_name) xo::InitSubsys<XO_SUBSYSTEM_TAG(subsys_name)>::require();
/* e.g. XO_SUBSYSTEM_PROVIDE(simulator, &init) =>
* xo::Subsystem::provide<xo::S_simulator_tag>("simulator", &init)
*/
#define XO_SUBSYSTEM_PROVIDE(subsys_name, init_addr) xo::Subsystem::provide<XO_SUBSYSTEM_TAG(subsys_name)>(STRINGIFY(subsys_name), init_addr)
//#define VERIFY_SUBSYSTEM(tag) Subsystem::verify_present<tag>(STRINGIFY(tag))
namespace xo {
using xo::tostr;
/* evidence that one or more subsystems have been initialized.
* Used to prevent static linker stripping must-run initialization code
*/
class InitEvidence {
public:
InitEvidence() = default;
InitEvidence(std::uint64_t x) : evidence_{x} {}
std::uint64_t evidence() const { return evidence_; }
InitEvidence operator^=(InitEvidence x) {
this->evidence_ ^= x.evidence_;
return *this;
} /*operator^=*/
InitEvidence operator^(InitEvidence x) {
return InitEvidence(this->evidence_ ^ x.evidence_);
}
private:
/* we don't care about the specific value computed here,
* purpose is to be sufficiently impenentrable to compiler such
* that static linker can't optimize it away
*/
std::uint64_t evidence_ = 0;
}; /*InitEvidence*/
inline std::ostream &
operator<<(std::ostream & os, InitEvidence x) {
os << "<init-evidence " << x.evidence() << ">";
return os;
} /*operator<<*/
/* Goals:
* 1. provide for code that must run once (and only once)
* to initialize subsystems
* 2. in executable, want to run such code after main() starts
* instead of relying on static initializers;
* that way init behavior can be parameterized based on
* program arguments
*
* Use
* // subsystem foo
*
* enum Foo_tag {};
*
* // guarantees that if anything gets initialized, then
* // foo_init() is included
* //
* template<>
* struct InitSubsys<Foo_tag> {
* static void foo_init() { ... }
*
* static InitEvidence require() {
* return Subsystem::require<Foo_tag>("foo", &foo_init);
* }
* };
*
* .. register other subsystems ..
*
* Subsystem::initialize_all(); // foo_init() has been called once
*
* If subsystem bar depends on supporting subsystem {foo, quux}, then write:
*
* enum Bar_tag {};
*
* template<>
* struct InitSubsys<Bar_tag> {
* static void bar_init() { ... }
*
* static InitEvidence require() {
* InitEvidence retval;
*
* retval ^= InitSubsys<Foo_tag>::require();
* retval ^= InitSubsys<Quux_tag>::require();
*
* retval ^= Subsystem::require<Bar_tag>("bar", &bar_init);
* }
* };
*
* If using subsystems from a shared library (so no access to cmdline args etc):
* e.g. in pyfoo.cpp:
*
* InitEvidence s_pyfoo_init = InitSubsys<Foo_tag>::require();
* or
* InitEvidence s_pyfoo_init = (InitSubsys<Foo_tag>::require()
* ^ InitSubsys<Bar_tag>::require());
*
* Note: Tag argument here no relation of BuildTag in SubsystemImpl<BuildTag> below
*/
template<typename Tag>
struct InitSubsys {};
/* BuildTag: placeholder; insisting on header-only library */
template <typename BuildTag>
class SubsystemImpl {
public:
SubsystemImpl() = default;
SubsystemImpl(bool require_flag,
std::string_view subsys_name,
std::function<void ()> init_fn)
: require_flag_{require_flag},
subsys_name_{subsys_name},
init_fn_{init_fn} {}
/* establish an empty Subsystem record for subsys_name.
* record is _not_ linked into s_subsys_l!
* idempotent.
*/
template<typename SubsystemTag>
static SubsystemImpl * establish() {
static SubsystemImpl s_subsys;
return &s_subsys;
} /*establish*/
template<typename SubsystemTag>
static bool verify_present(std::string subsys_tag) {
SubsystemImpl * subsys = establish<SubsystemTag>();
if (!subsys->require_flag()) {
throw std::runtime_error(tostr("subsystem not present."
"(missing InitSubsys<", subsys_tag, ">::require() ?)"));
return false;
}
return true;
} /*verify_present*/
/* provide (once only) initialization code for a subsystem with tag SubsystemTag.
* ideally this would be called just once for a particular tag;
* if called multiple times, calls after the first are no-ops.
*/
template<typename SubsystemTag>
static InitEvidence provide(std::string_view subsys_name,
std::function<void ()> init_fn) {
SubsystemImpl * subsys = establish<SubsystemTag>();
provide_aux(subsys_name, init_fn, subsys);
return InitEvidence(reinterpret_cast<std::uint64_t>(subsys));
} /*provide*/
/* throw exception if there's anything left for .initialize_all() to do,
* or subsystems have been added since last call to .initialize_all()
* Can use this to remind application author to call SubsystemImpl::initialize_all()
*/
static bool verify_all_initialized();
/* 1. initialize all subsystems: promise that for every preceding call
* to .require<tag>(), the corresponding initialization function has been
* run exactly once.
* 2. harmless to call this multiple times -- will not call any init_fn more than once
* 3. can interleave .initialize_all() with .require<tag>() as desired
*/
static InitEvidence initialize_all();
bool require_flag() const { return require_flag_; }
bool init_flag() const { return init_flag_; }
std::string_view subsys_name() const { return subsys_name_; }
InitEvidence initialize();
private:
/* helper for .provide<SubsystemTag>() */
static void provide_aux(std::string_view subsys_name,
std::function<void ()> init_fn,
SubsystemImpl * p_subsys);
private:
/* set to true iff .s_subsys_l has been extended since last call to .initialize_all() */
static bool s_dirty_flag;
/* one member for each unique call to .require() */
static std::list<SubsystemImpl *> s_subsys_l;
private:
/* set to true on 1st call to .require() */
bool require_flag_ = false;
/* set to true when .init_fn() invoked */
bool init_flag_ = false;
/* unique subsystem name */
std::string_view subsys_name_;
/* call this function once (at most) to initialize this subsystem */
std::function<void ()> init_fn_;
}; /*SubsystemImpl*/
template <typename BuildTag>
bool
SubsystemImpl<BuildTag>::s_dirty_flag = false;
template <typename BuildTag>
std::list<SubsystemImpl<BuildTag> *>
SubsystemImpl<BuildTag>::s_subsys_l;
template <typename BuildTag>
void
SubsystemImpl<BuildTag>::provide_aux(std::string_view subsys_name,
std::function<void ()> init_fn,
SubsystemImpl<BuildTag> * p_subsys)
{
if (!p_subsys->require_flag()) {
/* 1st call to .provide() for this SubsystemTag */
using xo::scope;
using xo::xtag;
scope log(XO_ENTER0(chatty),
xtag("subsys", subsys_name),
xtag("address", p_subsys));
*p_subsys = SubsystemImpl<BuildTag>(true /*require_flag*/,
subsys_name,
init_fn);
s_dirty_flag = true;
s_subsys_l.push_back(p_subsys);
}
} /*provide_aux*/
template <typename BuildTag>
bool
SubsystemImpl<BuildTag>::verify_all_initialized()
{
if (s_dirty_flag) {
scope log(XO_ENTER0(error), "required subsystems NOT initialized!?");
for (SubsystemImpl<BuildTag> * subsys : s_subsys_l) {
if (!subsys->init_flag()) {
log && log("missing InitSubsys<S_", subsys->subsys_name(), "_tag>::require()");
}
}
throw std::runtime_error("Subsystem::verify_initialized:"
" Subsystem::initialize_all() never called, or out-of-date");
return false;
}
return true;
} /*verify_all_initialized*/
template <typename BuildTag>
InitEvidence
SubsystemImpl<BuildTag>::initialize_all() {
scope log(XO_ENTER0(chatty));
InitEvidence retval;
if (s_dirty_flag) {
for (SubsystemImpl<BuildTag> * subsys : s_subsys_l) {
log && log("init", xtag("subsys", subsys->subsys_name()));
retval ^= subsys->initialize();
}
}
s_dirty_flag = false;
return retval;
} /*initialize_all*/
template <typename BuildTag>
InitEvidence
SubsystemImpl<BuildTag>::initialize()
{
if (!init_flag_) {
init_flag_ = true;
init_fn_();
}
return InitEvidence(reinterpret_cast<std::uint64_t>(this));
} /*initialize*/
using Subsystem = SubsystemImpl<class Subsystem_tag>;
} /*namespace xo*/
/* end Subsystem.hpp */