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.. regarding copyright ownership.  The ASF licenses this file
.. to you 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
..
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.. 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
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.. highlight:: none

How-to Commit
=============

If you are a committer, feel free to pick any process that works for you - so long as you are planning to commit the work yourself.

Patch based Contribution
------------------------

Here is how committing and merging will usually look for merging and pushing for tickets that follow the convention (if patch-based):

Hypothetical CASSANDRA-12345 ticket is a cassandra-3.0 based bug fix that requires different code for cassandra-3.11, cassandra-4.0, and trunk. Contributor Jackie supplied a patch for the root branch (12345-3.0.patch), and patches for the remaining branches (12345-3.11.patch, 12345-4.0.patch, 12345-trunk.patch).

On cassandra-3.0:
   #. ``git am -3 12345-3.0.patch`` (any problem b/c of CHANGES.txt not merging anymore, fix it in place)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)

On cassandra-3.11:
   #. ``git merge cassandra-3.0 -s ours``
   #. ``git apply -3 12345-3.11.patch`` (any issue with CHANGES.txt : fix and `git add CHANGES.txt`)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)
   #. ``git commit --amend`` (Notice this will squash the 3.11 applied patch into the forward merge commit)

On cassandra-4.0:
   #. ``git merge cassandra-3.11 -s ours``
   #. ``git apply -3 12345-4.0.patch`` (any issue with CHANGES.txt : fix and `git add CHANGES.txt`)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)
   #. ``git commit --amend`` (Notice this will squash the 4.0 applied patch into the forward merge commit)

On trunk:
   #. ``git merge cassandra-4.0 -s ours``
   #. ``git apply -3 12345-trunk.patch`` (any issue with CHANGES.txt : fix and `git add CHANGES.txt`)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)
   #. ``git commit --amend`` (Notice this will squash the trunk applied patch into the forward merge commit)

On any branch:
   #. ``git push origin cassandra-3.0 cassandra-3.11 cassandra-4.0 trunk --atomic -n`` (dryrun check)
   #. ``git push origin cassandra-3.0 cassandra-3.11 cassandra-4.0 trunk --atomic``


Git branch based Contribution
-----------------------------

Same scenario, but a branch-based contribution:

On cassandra-3.0:
   #. ``git cherry-pick <sha-of-3.0-commit>`` (any problem b/c of CHANGES.txt not merging anymore, fix it in place)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)

On cassandra-3.11:
   #. ``git merge cassandra-3.0 -s ours``
   #. ``git format-patch -1 <sha-of-3.11-commit>`` (alternative to format-patch and apply is `cherry-pick -n`)
   #. ``git apply -3 <sha-of-3.11-commit>.patch`` (any issue with CHANGES.txt : fix and `git add CHANGES.txt`)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)
   #. ``git commit --amend`` (Notice this will squash the 3.11 applied patch into the forward merge commit)

On cassandra-4.0:
   #. ``git merge cassandra-3.11 -s ours``
   #. ``git format-patch -1 <sha-of-4.0-commit>`` (alternative to format-patch and apply is `cherry-pick -n`)
   #. ``git apply -3 <sha-of-4.0-commit>.patch`` (any issue with CHANGES.txt : fix and `git add CHANGES.txt`)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)
   #. ``git commit --amend`` (Notice this will squash the 4.0 applied patch into the forward merge commit)

On trunk:
   #. ``git merge cassandra-4.0 -s ours``
   #. ``git format-patch -1 <sha-of-trunk-commit>`` (alternative to format-patch and apply is `cherry-pick -n`)
   #. ``git apply -3 <sha-of-trunk-commit>.patch`` (any issue with CHANGES.txt : fix and `git add CHANGES.txt`)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)
   #. ``git commit --amend`` (Notice this will squash the trunk applied patch into the forward merge commit)

On any branch:
   #. ``git push origin cassandra-3.0 cassandra-3.11 cassandra-4.0 trunk --atomic -n`` (dryrun check)
   #. ``git push origin cassandra-3.0 cassandra-3.11 cassandra-4.0 trunk --atomic``


Contributions only for release branches
---------------------------------------

If the patch is for an older branch, and doesn't impact later branches (such as trunk), we still need to merge up.

On cassandra-3.0:
   #. ``git cherry-pick <sha-of-3.0-commit>`` (any problem b/c of CHANGES.txt not merging anymore, fix it in place)
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)

On cassandra-3.11:
   #. ``git merge cassandra-3.0 -s ours``
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)

On cassandra-4.0:
   #. ``git merge cassandra-3.11 -s ours``
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)

On trunk:
   #. ``git merge cassandra-4.0 -s ours``
   #. ``ant realclean && ant jar build-test`` (rebuild to make sure code compiles)

On any branch:
   #. ``git push origin cassandra-3.0 cassandra-3.11 cassandra-4.0 trunk --atomic -n`` (dryrun check)
   #. ``git push origin cassandra-3.0 cassandra-3.11 cassandra-4.0 trunk --atomic``


Tips
----

.. tip::

   A template for commit messages:

  ::

      <One sentence description, usually Jira title or CHANGES.txt summary>
      <Optional lengthier description>

      patch by <Authors>; reviewed by <Reviewers> for CASSANDRA-#####


      Co-authored-by: Name1 <email1>
      Co-authored-by: Name2 <email2>

.. tip::

   Notes on git flags:
   ``-3`` flag to am and apply will instruct git to perform a 3-way merge for you. If a conflict is detected, you can either resolve it manually or invoke git mergetool - for both am and apply.

   ``--atomic`` flag to git push does the obvious thing: pushes all or nothing. Without the flag, the command is equivalent to running git push once per each branch. This is nifty in case a race condition happens - you won’t push half the branches, blocking other committers’ progress while you are resolving the issue.

.. tip::

   The fastest way to get a patch from someone’s commit in a branch on GH - if you don’t have their repo in remotes -  is to append .patch to the commit url, e.g.
   curl -O https://github.com/apache/cassandra/commit/7374e9b5ab08c1f1e612bf72293ea14c959b0c3c.patch

.. tip::

   ``git cherry-pick -n <sha-of-X.X-commit>`` can be used in place of the ``git format-patch -1 <sha-of-X.X-commit> ; git apply -3 <sha-of-X.X-commit>.patch`` steps.