HOW_TO_SNAPSHOT

Developers of Kokkos (those who commit modifications to Kokkos)
must maintain the snapshot of Kokkos in the Trilinos repository.

This file contains instructions for how to
snapshot Kokkos from github.com/kokkos to Trilinos.

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*** EVERYTHING GOES RIGHT WORKFLOW ***

1) Given a 'git clone' of Kokkos and of Trilinos repositories.
1.1) Let ${KOKKOS} be the absolute path to the Kokkos clone.
     This path *must* terminate with the directory name 'kokkos';
     e.g., ${HOME}/kokkos .
1.2) Let ${TRILINOS} be the absolute path to the Trilinos directory.

2) Given that the Kokkos build & test is clean and
   changes are committed to the Kokkos clone.

3) Snapshot the current commit in the Kokkos clone into the Trilinos clone.
   This overwrites ${TRILINOS}/packages/kokkos with the content of ${KOKKOS}:
	${KOKKOS}/config/snapshot.py --verbose ${KOKKOS} ${TRILINOS}/packages

4) Verify the snapshot commit happened as expected
	cd ${TRILINOS}/packages/kokkos
	git log -1 --name-only

5) Modify, build, and test Trilinos with the Kokkos snapshot.

6) Given that that the Trilinos build & test is clean and
   changes are committed to the Trilinos clone.

7) Attempt push to the Kokkos repository.
   If push fails then you must 'remove the Kokkos snapshot'
   from your Trilinos clone.
   See below.

8) Attempt to push to the Trilinos repository.
   If updating for a failed push requires you to change Kokkos you must
   'remove the Kokkos snapshot' from your Trilinos clone.
   See below.

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*** WHEN SOMETHING GOES WRONG AND YOU MUST              ***
*** REMOVE THE KOKKOS SNAPSHOT FROM YOUR TRILINOS CLONE ***

1) Query the Trilinos clone commit log.
	git log --oneline

2) Note the <SHA1> of the commit to the Trillinos clone
   immediately BEFORE the Kokkos snapshot commit.
   Copy this <SHA1> for use in the next command.

3) IF more than one outstanding commit then you can remove just the
   Kokkos snapshot commit with 'git rebase -i'.  Edit the rebase file.
   Remove or comment out the Kokkos snapshot commit entry.
	git rebase -i <SHA1>

4) IF the Kokkos snapshot commit is the one and only
   outstanding commit then remove just than commit.
	git reset --hard HEAD~1

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*** REGARDING 'snapshot.py' TOOL ***

The 'snapshot.py' tool is developed and maintained by the
Center for Computing Research (CCR)
Software Engineering, Maintenance, and Support (SEMS) team.

Contact Brent Perschbacher <bmpersc@sandia.gov> for questions>

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