This rewrites the top-level loop of hydra-evaluator in C++. The Perl
stuff is moved into hydra-eval-jobset. (Rewriting the entire evaluator
would be nice but is a bit too much work.) The new version has some
advantages:
* It can run multiple jobset evaluations in parallel.
* It uses PostgreSQL notifications so it doesn't have to poll the
database. So if a jobset is triggered via the web interface or from
a GitHub / Bitbucket webhook, evaluation of the jobset will start
almost instantaneously (assuming the evaluator is not at its
concurrency limit).
* It imposes a timeout on evaluations. So if e.g. hydra-eval-jobset
hangs connecting to a Mercurial server, it will eventually be
killed.
The catalyst-action-rest branch from shlevy/hydra was an exploration of
using Catalyst::Action::REST to create a JSON API for hydra. This commit
merges in the best bits from that experiment, with the goal that further
API endpoints can be added incrementally.
In addition to migrating more endpoints, there is potential for
improvement in what's already been done:
* The web interface can be updated to use the same non-GET endpoints as
the JSON interface (using x-tunneled-method) instead of having a
separate endpoint
* The web rendering should use the $c->stash->{resource} data structure
where applicable rather than putting the same data in two places in
the stash
* Which columns to render for each endpoint is a completely debatable
question
* Hydra::Component::ToJSON should turn has_many relations that have
strings as their primary keys into objects instead of arrays
FixesNixOS/hydra#98
Signed-off-by: Shea Levy <shea@shealevy.com>
