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Add resource auto grouping

Sorry for the size of this patch, I was busy hacking and plumbing away
and it got out of hand! I'm allowing this because there doesn't seem to
be anyone hacking away on parts of the code that this would break, since
the resource code is fairly stable in this change. In particular, it
revisits and refreshes some areas of the code that didn't see anything
new or innovative since the project first started. I've gotten rid of a
lot of cruft, and in particular cleaned up some things that I didn't
know how to do better before! Here's hoping I'll continue to learn and
have more to improve upon in the future! (Well let's not hope _too_ hard
though!)

The logical goal of this patch was to make logical grouping of resources
possible. For example, it might be more efficient to group three package
installations into a single transaction, instead of having to run three
separate transactions. This is because a package installation typically
has an initial one-time per run cost which shouldn't need to be
repeated.

Another future goal would be to group file resources sharing a common
base path under a common recursive fanotify watcher. Since this depends
on fanotify capabilities first, this hasn't been implemented yet, but
could be a useful method of reducing the number of separate watches
needed, since there is a finite limit.

It's worth mentioning that grouping resources typically _reduces_ the
parallel execution capability of a particular graph, but depending on
the cost/benefit tradeoff, this might be preferential. I'd submit it's
almost universally beneficial for pkg resources.

This monster patch includes:
* the autogroup feature
* the grouping interface
* a placeholder algorithm
* an extensive test case infrastructure to test grouping algorithms
* a move of some base resource methods into pgraph refactoring
* some config/compile clean ups to remove code duplication
* b64 encoding/decoding improvements
* a rename of the yaml "res" entries to "kind" (more logical)
* some docs
* small fixes
* and more!
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1 parent 9720812 commit 1b01f908e3ada686024ad144637ea0dd0ab64762 @purpleidea committed Mar 20, 2016
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@@ -32,6 +32,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
3. [Setup - Getting started with mgmt](#setup)
4. [Features - All things mgmt can do](#features)
* [Autoedges - Automatic resource relationships](#autoedges)
+ * [Autogrouping - Automatic resource grouping](#autogrouping)
5. [Usage/FAQ - Notes on usage and frequently asked questions](#usage-and-frequently-asked-questions)
6. [Reference - Detailed reference](#reference)
* [Graph definition file](#graph-definition-file)
@@ -94,8 +95,22 @@ order to handle this situation you can disable autoedges per resource and
explicitly declare that you want `my.cnf` to be written to disk before the
installation of the `mysql-server` package.
-You can disable autoedges for a resource by setting the `autoedge` key for
-the meta attributes of a resource to `false`.
+You can disable autoedges for a resource by setting the `autoedge` key on
+the meta attributes of that resource to `false`.
+
+###Autogrouping
+
+Automatic grouping or AutoGroup is the mechanism in mgmt by which it will
+automatically group multiple resource vertices into a single one. This is
+particularly useful for grouping multiple package resources into a single
+resource, since the multiple installations can happen together in a single
+transaction, which saves a lot of time because package resources typically have
+a large fixed cost to running (downloading and verifying the package repo) and
+if they are grouped they share this fixed cost. This grouping feature can be
+used for other use cases too.
+
+You can disable autogrouping for a resource by setting the `autogroup` key on
+the meta attributes of that resource to `false`.
##Usage and frequently asked questions
(Send your questions as a patch to this FAQ! I'll review it, merge it, and
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