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Contributing to Eclipse iceoryx

Thanks for your interest in this project.

Project description

In domains like automotive, robotics or gaming, a huge amount of data must be transferred between different parts of the system. If these parts are actually different processes on a POSIX based operating system like Linux, this huge amount of data has to be transferred via an inter-process-communication (IPC) mechanism. Find more infos on the Eclipse site.

Eclipse Contributor Agreement

Before your contribution can be accepted by the project team, contributors must electronically sign the Eclipse Contributor Agreement (ECA).

Commits that are provided by non-committers must have a Signed-off-by field in the footer indicating that the author is aware of the terms by which the contribution has been provided to the project. The non-committer must additionally have an Eclipse Foundation account and must have a signed Eclipse Contributor Agreement (ECA) on file.

For more information, please see the Eclipse Committer Handbook.

Contact

Contact the project developers via the project's "dev" list.

Feature request and bugs

We love pull requests! The next sections try to cover most of the relevant questions. For larger contributions or architectural changes, we'd kindly ask you to either:

or

  • Create a design document and raise it in a separate pull request beforehand

If you would like to report a bug or propose a new feature, please raise an issue before raising a pull request. Please have a quick search upfront if a similar issue already exists. An release board is used to prioritize the issues for a specific release. This makes it easier to track the work-in-progress. If you have troubles getting an issue assigned to you please contact the maintainers via Gitter.

Please make sure you have:

  1. Signed the Eclipse Contributor Agreement
  2. Created an issue before creating a branch, e.g. Super duper feature with issue number 123
  3. All branches have the following naming format: iox-#[issue]-branch-name e.g. iox-#123-super-duper-feature
  4. All commits have the following naming format: iox-#[issue] commit message e.g. iox-#123 implemented super-duper feature
  5. All commits have been signed with git commit -s
  6. You open your pull request towards the base branch staging
  7. Link the pull request to the according Github issue and set the label accordingly

Coding style

We love the C++ core guidelines. If in doubt please try to follow them as well as our unwritten conventions in the existing parts of the code base. Please format your code with the provided clang-format and clang-tidy before raising a pull request. Lots of IDEs do read the clang-format file these days.

We created some convenient rules to highlight some bits that you might not be used to in other FOSS projects. They are helpful to build embedded systems for safety fields like automotive or avionics. It is possible that not the whole codebase follows these rules, things are work in progress.

  1. No heap is allowed, static memory management hugely decreases the complexity of your software (e.g. cxx::vector without heap)
  2. No exception are allowed, all function and methods need to have noexcept in their signature
  3. No undefined behavior, zero-cost abstract is not feasible in high safety environments
  4. Use C++14
  5. Rule of Five, if there is a non-default destructor needed, the rule of five has to be applied
  6. STL, we aim to be compatible towards the STL, but our code may contain additions which are not compatible with the STL (e.g. iox::cxx::vector::emplace_back() does return a bool)
  7. Always use iox::log::Logger, instead of printf()
  8. Always use iox::ErrorHandler(), instead of the direct STL calls

See error-handling.md for additional information about logging and error handling.

Naming conventions

  • File names with lower_snake_case: my_thing.hpp
  • Structs, classes and enum classes in UpperCamelCase: class MyClass{}
  • Methods and variables in lowerCamelCase: uint16_t myVariable
  • Compile time constants, also enum values in UPPER_SNAKE_CASE: static constexpr uint16_t MY_CONSTANT
  • Class members start with m_: m_myMember
    • Public members of structs and classes do not have the m_ prefix
  • Namespaces in lower_snake_case : my_namespace
  • Aliases have a _t postfix : using FooString_t = iox::cxx::string<100>;

Doxygen

Please use doxygen to document your code.

The following doxygen comments are required for public API headers:

/// @brief short description
/// @param[in] / [out] / [in,out] name description
/// @return description

A good example for code formatting and doxygen structure is at swe_docu_guidelines.md (WIP)

Folder structure

The folder structure boils down to:

  • iceoryx_COMPONENT
    • cmake: All cmakes files go here, needed for find_pkg()
    • doc: Manuals and documentation
    • include: public headers with stable API
      • internal: public headers with unstable API, which might change quite frequently
    • source: implementation files
    • test: unit and integration tests
    • CMakeLists.txt: Build the component separately
  • examples_iceoryx: Examples described in iceoryx_examples

All new code should follow the folder structure.

Testing

We use Google test for our unit and integration tests. We require compatibility with the version 1.8.1.

Unit tests (aka module tests)

Unit tests are black box tests that test the public interface of a class. They are required for all new code.

Integration tests

Integration tests are composition of more than one class and test their interaction. They are optional for new code.

Coverage Scan

To ensure that the provided testcode covers the productive code you can do a coverage scan with gcov. The reporting is done with lcov and htmlgen. You will need to install the following packages:

sudo apt install lcov

In iceoryx we have multiple testlevels for testcoverage: 'unit', 'integration', 'component' and ’all’ for all testlevels together. You can create reports for these different testlevels or for all tests. Coverage is done with gcc. The coverage scan applies to Quality level 3 and partly level 2 with branch coverage.

For having a coverage report iceoryx needs to be compiled with coverage flags and the tests needs to be executed. You can do this with one command in iceroyx folder like this:

./tools/iceoryx_build_test.sh clean build-all -c <testlevel>

Optionally you can use build-all option to get coverage for extensions like DDS or C-Binding. The -c flag indicates that you want to have a coverage report and you can pass there the needed testlevel. Per default the testlevel is set to 'all'. example:

./tools/iceoryx_build_test.sh build-all clean -c unit

For having only reports for unit-test. In the script tools/gcov/lcov_generate.sh is the initial scan, filtering and report generation automatically done.

All reports are stored in build/lcov as html report (index.html).

Legal & Compliance

Dependencies

  • POSIX Iceoryx aims to be fully POSIX-compliant towards the current revision POSIX.1-2017 (IEEE 1003.1-2017). Please write your code as portable as possible. Currently our focus is QNX (QCC 5.4) and Linux (GCC 7.5.0).

  • ACL

  • ncurses

Safety & security

We aim for ASIL-D compliance. The ISO26262 is also a good read-up if you want to learn more about automotive safety. A nice introduction video was presented on CppCon 2019.

If you want to report a vulnerability, please use the Eclipse process.

We have a partnership with Perforce and use Helix QAC++ 2019.2 to perform a static-code analysis.

Github labels are used to group issues into the rulesets:

Ruleset name Github issue label
MISRA C++ 2008 MISRA
Adaptive AUTOSAR C++14 AUTOSAR
SEI CERT C++ 2016 Coding Standard CERT

If one of the rules is not followed, a rationale is added in the following manner:

With a comment in the same line:

*mynullptr = foo; // PRQA S 4242 # Short description why

With a comment one line above (with the number after the warning number, next ’n’ lines are inclusive)

// PRQA S 4242 1 # Short description why
*mynullptr = foo;

Don't be afraid if you don't have Helix QAC++ available. As we want to make it easy for developers to contribute, please use the staging branch and we'll run the QAC++ scan and get back to you.

Results will be available on this Helix QAC dashboard. Please contact one of the maintainers, if you're interested in getting access.

It is possible that not the whole codebase follows these rules, things are work in progress. But this is where we want go. As of now we don't have any continuos integration checks implemented but will rely on reviews during the pull requests. We're planning to introduce continuos integration checks in the near future.

Header

Each source file needs to have this header:

    // Copyright (c) [DATE] by [INITIAL COPYRIGHT OWNER] [OTHER COPYRIGHT OWNERS]. All rights reserved.
    //
    // Licensed under the Apache License, Version 2.0 (the "License");
    // you may not use this file except in compliance with the License.
    // You may obtain a copy of the License at
    //
    //     http://www.apache.org/licenses/LICENSE-2.0
    //
    // Unless required by applicable law or agreed to in writing, software
    // distributed under the License is distributed on an "AS IS" BASIS,
    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    // See the License for the specific language governing permissions and
    // limitations under the License.

Note: DATE is either a year or a range of years with the first and last years of the range separated by a comma. So for example: "2004" or "2000, 2004". The first year is when the contents of the file were first created and the last year is when the contents were last modified.

Example:

    // Copyright (c) 2018, 2020 by ACME Corp, Globex. All rights reserved.
    //
    // Licensed under the Apache License, Version 2.0 (the "License");
    // you may not use this file except in compliance with the License.
    // You may obtain a copy of the License at
    //
    //     http://www.apache.org/licenses/LICENSE-2.0
    //
    // Unless required by applicable law or agreed to in writing, software
    // distributed under the License is distributed on an "AS IS" BASIS,
    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    // See the License for the specific language governing permissions and
    // limitations under the License.

Quality levels

CMake targets can be developed according to different quality levels. Despite developing some of our targets according to automotive standards like ISO26262, the code base standalone does NOT legitimize the usage in a safety critical system. All requirements of a lower quality level are included in higher quality levels e.g. quality level 4 is included in quality level 3.

Also see ROS quality levels.

Quality level 5

This quality level is the default quality level. It is meant for examples and helper tools.

  • Reviewed by two approver
  • License and copyright statement available
  • No version policy required
  • No unit tests required

Quality level 4

This quality level is meant for all targets that need tier 1 support in ROS2.

  • Basic unit tests are available

Quality level 3

  • No compiler warnings
  • Doxygen and documentation available
  • Test specification available
  • Version policy required
  • Level 8 and 9 warnings in Helix QAC addressed

Quality level 2

  • Unit tests have full statement and branch coverage

Quality level 1

  • Warnings in Helix QAC addressed
  • Code coverage according to MC/DC available

Training material recommended for contributors

  • Effective C++ by Scott Meyers
  • Unit Testing and the Arrange, Act and Assert (AAA) Pattern by Paulo Gomes
  • The C++ Standard Library by Nicolai M. Josuttis
  • Modern C++ Programming with Test-Driven Development: Code Better, Sleep Better by Jeff Langr
  • Modern C++ Design: Generic Programming and Design Patterns by Andrei Alexandrescu
  • Exceptional C++ by Herb Sutter
  • C++ Concurrency in Action by Anthony Williams