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!
I didn't know this was possible until I was browsing through some golang
docs recently. This should hopefully make it clearer which the common
methods to all resources are (which don't need to be reimplemented each
time) and which ones are unique and need to be created for each
resource.
By adding the "kind" to the base resource, it is still identifiable even
when the resource specific elements are gone in calls that are only
defined in the base resource. This is also more logical for building
resources!
This also switches resources to use an Init() method. This will be
useful for when resources have more complex initialization to do.
This allows for resources to automatically add necessary edges to the
graph so that the event system doesn't have to work overtime due to
sub-optimal execution order.
This used to be GetType(), but since now things are "resources", we want
to know what "kind" they are, since asking what "type" they are is
confusing, and makes less logical sense than "Kind".
This simplifies the API, and reduces code duplication for most
resources. It became obvious when writing the pkg resource, that the two
operations should really be one. Hopefully this will last! Comments
welcome.
Naming the resources "type" was a stupid mistake, and is a huge source
of confusion when also talking about real types. Fix this before it gets
out of hand.
