Overhaul OptimizeBaskets algorithm.

[bbockelm]

This is an overhaul of the optimize baskets algorithm, primarily done by Ilija Vukotic and extended by David Smith.

Goal of this algorithm is to minimize overall memory size when writing and number of baskets in a cluster.

Since this work predates ROOT moving to GitHub, it appears the patches primarily are floating around in various people's inbox. This is my attempt to "capture" the knowledge and ideas, even if we don't decide to go this direction.

@pcanal @smithdh

[phsft-bot]

Can one of the admins verify this patch?

[Teemperor]

@phsft-bot build

[phsft-bot]

Starting build on gcc49/centos7, native/mac1012, gcc49/slc6, gcc62/slc6, native/ubuntu14 with flags -Dvc=OFF -Dimt=ON -Dccache=ON
How to customize builds

[phsft-bot]

Build failed on ubuntu14/native.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[phsft-bot]

Build failed on mac1012/native.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[phsft-bot]

Build failed on centos7/gcc49.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[phsft-bot]

Build failed on slc6/gcc49.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[phsft-bot]

Build failed on slc6/gcc62.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[amadio]

@phsft-bot build

[phsft-bot]

Starting build on centos7/gcc49, mac1012/native, slc6/gcc49, slc6/gcc62, ubuntu14/native with flags -Dvc=OFF -Dimt=ON -Dccache=ON
How to customize builds

[phsft-bot]

Build failed on ubuntu14/native.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[amadio]

@bbockelm Could you please check the errors reported by Jenkins? The test failure does seem to be caused by the changes in this PR.

[phsft-bot]

Build failed on mac1012/native.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[phsft-bot]

Build failed on centos7/gcc49.
See console output.

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[phsft-bot]

Build failed on slc6/gcc62.
See console output.

Errors:

• ERROR: Timeout after 10 minutes
• ERROR: Error fetching remote repo 'origin'
• stderr: error: RPC failed; result=18, HTTP code = 200
• ERROR: Error fetching remote repo 'origin'

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[phsft-bot]

Build failed on slc6/gcc49.
See console output.

Errors:

• ERROR: Timeout after 10 minutes
• ERROR: Error fetching remote repo 'origin'
• stderr: error: RPC failed; result=18, HTTP code = 200
• ERROR: Error fetching remote repo 'origin'

Failing tests:

• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache

[bbockelm]

Closing this PR -- now that it's recorded in GitHub instead of personal email threads, we can revisit at any time in the future.