Hephaestus

Hephaestus is a C++ framework designed to facilitate robotics development by providing commonly needed functionality and abstractions.

The goal of Hephaestus is to support the deployment of robotic code in production. This means:

• Simple, stable, performant functionalities.
• No focus on simplifying experimentation and no-nonsense functionality.
  • New features will be added if they make production code better (faster/stable/simpler), not for making running experiments faster (I am looking at you ROS).
• Abstract from the developer as much of the complexity of writing C++ code as possible:
  • Memory managment.
  • Parallelism and multi/threading.
  • Containers and basic algorithm.

Hephaestus provides functionalities that cover the following domains:

• Inter Process Comunication (IPC).
• Data serialization for IPC and storage.
• Multi-threading, e.g. thread pools and parallelism primitive.
• Containers, e.g. thread safe containers for sharing data across threads.
• Memory pool.
• Functionalities to run real-time code.

NOTE: most of the above functionalities are still work in progress.

Build

Env

The best way to build hephaestus is to do it inside the docker container provided in the docker folder. You can build the container with build.sh and start it using run.sh.

Compilation

Hephaestus uses CMake to build, the build infrastructure is copied and adapted from grape.

To build it:

cd hephaestus
mkdir build && cd build
cmake --preset default
ninja all examples

To compile and run the unit test

ninja check

TODO: add section on the different flags and options.

Build system

You can use the build system of hephaestus in your own project by importing the CMake files and recreating the required folder structure.

Create the top level CMakeLists.txt as:

cmake_minimum_required(VERSION 3.22.1)
project(my_project LANGUAGES CXX C)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

include(FetchContent)
FetchContent_Declare(
    hephaestus
    GIT_REPOSITORY "https://github.com/olympus-robotics/hephaestus.git"
    GIT_TAG "main"
)
FetchContent_GetProperties(hephaestus)
if(NOT hephaestus_POPULATED)
  FetchContent_Populate(hephaestus)
endif()

# If you want to use hephaestus toolchain add:
# set(CMAKE_TOOLCHAIN_FILE ${hephaestus_SOURCE_DIR}/toolchains/toolchain_clang.cmake)

# Include the Cmake functions.
include(${hephaestus_SOURCE_DIR}/cmake/build.cmake)

Create the modules folder and add your modules. You can use the hephaestus script by calling:

cd modules
python3 ../build/_deps/hephaestus-src/cmake/create_module.py my_module

Create the external folder and add a CMakeLists.txt file as:

cmake_minimum_required(VERSION 3.27.3)
project(my_project-external LANGUAGES C CXX)

include(${CMAKE_TEMPLATE_DIR}/external.cmake)

# Add your desired dependencies:
# add_cmake_dependency(
#     NAME hephaestus
#     GIT_REPOSITORY "https://github.com/olympus-robotics/hephaestus.git"
#     GIT_TAG "main"
#     CMAKE_ARGS -DBUILD_MODULES="utils"
# )

Using Hephaestus

There are multiple ways to use Hephaestus in your repo.

Global installation

Install hephaestus in a known folder, e.g. /install. When you compile your project pass -DCMAKE_PREFIX_PATH=/install and in your CMakeLists.txt:

find_package(hephaestus REQUIRED <component1> <component2>) # e.g. find_package(hephaestus REQUIRED ipc serdes)

add_library(my-lib ...)
target_link_libraries(my-lib
    PUBLIC hephaestus::ipc hephaestus::serdes
)

Use Hephaestus CMake build system

Using Hephaestus build system build hephaestus together with your project:

add_cmake_dependency(
    NAME hephaestus
    GIT_REPOSITORY "https://github.com/olympus-robotics/hephaestus.git"
    GIT_TAG "main"
    CMAKE_ARGS -DBUILD_MODULES="utils"
)

and in your library CMakeLists.txt:

find_package(hephaestus REQUIRED <component1> <component2>) # e.g. find_package(hephaestus REQUIRED ipc serdes)

add_library(my-lib ...)
target_link_libraries(my-lib
    PUBLIC hephaestus::ipc hephaestus::serdes
)

Include Hephaestus as a submodule

Add Hephaestus as a git submodule to your project (e.g. in third_party/hephaestus) and in the root CMakeLists.txt before adding your libraries add:

set(BUILD_MODULES "ipc;serdes") # or `all` if you want to build all of it.
add_subdirectory(third_party/hephaestus)

if you are using Hephaestus build system for your project you need to backup the modules list to keep it separate between the Hephaestus ones and yours:

set(hephaestus_SOURCE_DIR ${CMAKE_SOURCE_DIR}/third_party/hephaestus)

set(BUILD_MODULES_BAK ${BUILD_MODULES})
set(BUILD_MODULES "utils")
add_subdirectory(${hephaestus_SOURCE_DIR})

set(BUILD_MODULES ${BUILD_MODULES_BAK})
include(${hephaestus_SOURCE_DIR}/cmake/build.cmake)

Notes

Initially this repo was supporting C++23, but to maximise compatibilty we reverted back to C++20.

When switching again back to C++23 it will be possible to remove fmt and ranges-v3. The transition will be easy, just rename fmt:: -> std:: and remove fmt::formatter.

TODO

Hephaestus is under active development. The list of tasks to be carried out can be found under the Hephaestus Masterplan project.