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Contributing to pmemkv

Opening New Issues

Please log bugs or suggestions as GitHub issues. Details such as OS and PMDK version are always appreciated.

Code Style

  • Start with Google C++ Style
  • Indent 4 spaces, 8 spaces for continuation
  • Max 120 chars per line
  • Space after '*' and '&' (rather than before)

Submitting Pull Requests

We take outside code contributions to pmemkv through GitHub pull requests.

NOTE: If you do decide to implement code changes and contribute them, please make sure you agree your contribution can be made available under the BSD-style License used for the PMDK.

NOTE: Submitting your changes also means that you certify the following:

Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

In case of any doubt, the gatekeeper may ask you to certify the above in writing, i.e. via email or by including a Signed-off-by: line at the bottom of your commit comments.

To improve tracking of who is the author of a contribution, we kindly ask you to use your real name (not an alias) when committing your changes to the NVM Library:

Author: Random J Developer <>

Creating New Engines

There are several motivations to create a pmemkv storage engine:

  • Using a completely different implementation strategy than already exists
  • Trying out a signifcant change to an existing engine without disruption
  • Sharing an experimental engine that isn't even finished yet

Next we'll walk you through the steps of creating a new engine.

Picking Engine Name

  • Relatively short (users will have to type this!)
  • Formatted in all lower-case
  • No whitespace or special characters
  • For this example: mytree

Creating Engine Header

  • Create src/engines/mytree.h header file
  • For new engines, use blackhole.h as a template
  • Use pmemkv::mytree namespace to define internal types
  • Define ENGINE constant in namespace to export engine name
  • Use camel-case for implementation class name (class MyTree)

Creating Engine Implementation

  • Create src/engines/ implementation file
  • For new engines, use as a template
  • Use pmemkv::mytree namespace defined by the header

Providing Unit Test

  • Create tests/engines/ for unit tests
  • For new engines, use as a template
  • For stable engines, just copy existing tests (eventually replace the original)

Updating Build System

  • In CMakeLists.txt:
    • Add src/engines/mytree.h and src/engines/ to SOURCE_FILES
    • Add tests/ to pmemkv_test executable
    • Use pkg_check_modules and/or find_package for upstream libraries
  • make should now run to completion without errors

Updating KVEngine

  • In src/
    • Add #include "engines/mytree.h"
    • Update KVEngine::Open to return new MyTree instances
    • Update KVEngine::Close to delete MyTree instances
  • make & verify engine now works with high-level bindings


  • In, add mytree section
  • In, link mytree in the table of supported engines