..
    Copyright (c) 2007-2019 Louisiana State University

    SPDX-License-Identifier: BSL-1.0
    Distributed under the Boost Software License, Version 1.0. (See accompanying
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

|circleci_status| |zenodo_doi| |codacy|

Documentation: `latest
<https://stellar-group.github.io/hpx/docs/sphinx/latest/html/index.html>`_,
`development (master)
<https://stellar-group.github.io/hpx/docs/sphinx/branches/master/html/index.html>`_

===
HPX
===

HPX is a C++ Standard Library for Concurrency and Parallelism. It implements all
of the corresponding facilities as defined by the C++ Standard. Additionally, in
HPX we implement functionalities proposed as part of the ongoing C++
standardization process. We also extend the C++ Standard APIs to the distributed
case.

The goal of HPX is to create a high quality, freely available, open source
implementation of a new programming model for conventional systems, such as
classic Linux based Beowulf clusters or multi-socket highly parallel SMP nodes.
At the same time, we want to have a very modular and well designed runtime
system architecture which would allow us to port our implementation onto new
computer system architectures. We want to use real-world applications to drive
the development of the runtime system, coining out required functionalities and
converging onto a stable API which will provide a smooth migration path for
developers.

The API exposed by HPX is not only modeled after the interfaces defined by the
C++11/14/17/20 ISO standard, it also adheres to the programming guidelines used
by the Boost collection of C++ libraries. We aim to improve the scalability of
today's applications and to expose new levels of parallelism which are necessary
to take advantage of the exascale systems of the future.

What's so special about HPX?
============================

* HPX exposes a uniform, standards-oriented API for ease of programming parallel
  and distributed applications.
* It enables programmers to write fully asynchronous code using hundreds of
  millions of threads.
* HPX provides unified syntax and semantics for local and remote operations.
* HPX makes concurrency manageable with dataflow and future based
  synchronization.
* It implements a rich set of runtime services supporting a broad range of use
  cases.
* HPX exposes a uniform, flexible, and extendable performance counter framework
  which can enable runtime adaptivity
* It is designed to solve problems conventionally considered to be
  scaling-impaired.
* HPX has been designed and developed for systems of any scale, from hand-held
  devices to very large scale systems.
* It is the first fully functional implementation of the ParalleX execution
  model.
* HPX is published under a liberal open-source license and has an open, active,
  and thriving developer community.

Documentation
=============

If you plan to use HPX we suggest to start with the latest released version
which can be downloaded `here <https://stellar.cct.lsu.edu/downloads/>`_.

To quickly get started with HPX on most Linux distributions you can read the
quick start guide `here
<https://stellar-group.github.io/hpx/docs/sphinx/latest/html/quickstart.html>`_.
Detailed instructions on building and installing HPX on various platforms can be
found `here
<https://stellar-group.github.io/hpx/docs/sphinx/latest/html/manual/building_hpx.html>`_.
The full documentation for the latest release of HPX can always be found `here
<https://stellar-group.github.io/hpx/docs/sphinx/latest/html/index.html>`_.

If you would like to work with the cutting edge version of this repository
(``master`` branch) the documentation can be found `here
<https://stellar-group.github.io/hpx/docs/sphinx/branches/master/html/index.html>`_.
We strongly recommend that you follow the current health status of the master
branch by looking at our `continuous integration results website
<http://rostam.cct.lsu.edu/console>`_. While we try to keep the master branch
stable and usable, sometimes new bugs trick their way into the code base. The
`CircleCI <https://circleci.com/gh/STEllAR-GROUP/hpx>`_ continuous integration
service additionally tracks the current build status for the master branch:
|circleci_status|.

We use `Codacy <https://www.codacy.com/>`_ to assess the code quality of this
project: |codacy|.

If you can't find what you are looking for in the documentation or you suspect
you've found a bug in HPX we very much encourage and appreciate any issue
reports through the `issue tracker for this Github project
<https://github.com/STEllAR-GROUP/hpx/issues>`_.

If you have any questions feel free to ask it over at `StackOverflow
<https://stackoverflow.com>`_ and tag the question with `hpx
<https://stackoverflow.com/questions/tagged/hpx>`_.

For a full list of support options please see our `Support page
<https://github.com/STEllAR-GROUP/hpx/blob/master/.github/SUPPORT.md>`_.

Code of conduct
===============

We have adopted a `code of conduct
<https://github.com/STEllAR-GROUP/hpx/blob/master/.github/CODE_OF_CONDUCT.md>`_
for this project. Please refer to this document if you would like to know more
about the expectations for members of our community, with regard to how they
will behave toward each other.

Please find the project's gpg key, which is used to sign HPX releases
`here
<https://pgp.mit.edu/pks/lookup?op=get&search=0xE18AE35E86BB194F>`_.

Citing
======

In publications the latest release of HPX can be cited as: |zenodo_doi|.

Acknowledgements
================

We would like to acknowledge the NSF, DoE, DTIC, DARPA, the Center for
Computation and Technology (CCT) at Louisiana State University, and the
Department of Computer Science 3 - Computer Architecture at the University of
Erlangen Nuremberg who fund and support our work.

We would also like to thank the following organizations for granting us
allocations of their compute resources: LSU HPC, LONI, XSEDE, NERSC, CSCS/ETHZ,
and the Gauss Center for Supercomputing.

HPX is currently funded by

* The National Science Foundation through awards 1240655 (STAR), 1339782
  (STORM), and 1737785 (Phylanx).

  Any opinions, findings, and conclusions or recommendations expressed in this
  material are those of the author(s) and do not necessarily reflect the views
  of the National Science Foundation.

* The Department of Energy (DoE) through the awards DE-AC52-06NA25396 (FLeCSI)
  and DE-NA0003525 (Resilience).

  Neither the United States Government nor any agency thereof, nor any of their
  employees makes any warranty, express or implied, or assumes any legal
  liability or responsibility for the accuracy, completeness, or usefulness of
  any information, apparatus, product, or process disclosed, or represents that
  its use would not infringe privately owned rights. Reference herein to any
  specific commercial product, process, or service by trade name, trademark,
  manufacturer, or otherwise does not necessarily constitute or imply its
  endorsement, recommendation, or favoring by the United States Government or
  any agency thereof. The views and opinions of authors expressed herein do not
  necessarily state or reflect those of the United States Government or any
  agency thereof.

* The Defense Technical Information Center (DTIC) under contract
  FA8075-14-D-0002/0007

  Neither the United States Government nor any agency thereof, nor any of their
  employees makes any warranty, express or implied, or assumes any legal
  liability or responsibility for the accuracy, completeness, or usefulness of
  any information, apparatus, product, or process disclosed, or represents that
  its use would not infringe privately owned rights.

* The Bavarian Research Foundation (Bayerische Forschungsstiftung) through the
  grant AZ-987-11.

* The European Commission's Horizon 2020 programme through the grant
  H2020-EU.1.2.2. 671603 (AllScale).

.. |circleci_status| image:: https://circleci.com/gh/STEllAR-GROUP/hpx/tree/master.svg?style=svg
     :target: https://circleci.com/gh/STEllAR-GROUP/hpx/tree/master
     :alt: HPX master branch build status

.. |zenodo_doi| image:: https://zenodo.org/badge/DOI/10.5281/zenodo.598202.svg
     :target: https://doi.org/10.5281/zenodo.598202

.. |codacy| image:: https://api.codacy.com/project/badge/Grade/fef52e7a84d04123921152e35fbb1594
     :target: https://www.codacy.com/app/STEllAR-GROUP/hpx
     :alt: HPX Code Quality Assessment
