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>
Previously, for scheduled builds, "timestamp" contained the time the
build was added to the queue, while for finished builds, it was the
time the build finished. Now it's always the former.
This caused exceptions like:
Caught exception in Hydra::Controller::Build->view_build "writing to file: Broken pipe at /nix/store/ihdb3widsq1dk7sbl5vqjxfcxb5ypad4-hydra-0.1pre1297-8158093/libexec/hydra/lib/Hydra/Controller/Build.pm line 59."
because the connection to the Nix daemon would be terminated due to a
protocol violation (calling queryPathInfo with an empty string).
Because of the way DBIx::Class does prepared statements, even
innocuous queries such
$c->model('DB::Builds)->search({finished => 0})
can be extremely slow. This is because DBIx::Class prepares a
PostgreSQL statement
select ... from Builds where finished = ?
and since Builds is very large and there is a large fraction of rows
with "finished = 1", the PostgreSQL query planner decides to implement
this query with a sequential scan of the Builds table (despite the
existence of an index on "finished"), which is extremely slow. It
would be nice if we could tell DBIx::Class that constants should be
part of the prepared statement, i.e.
select ... from Builds where finished = 0
but AFAIK we can't.
Prepared statements are sometimes much slower than unprepared
statements, because the planner doesn't have access to the query
parameters. This is the case for the active build steps query (in
/status), where a prepared statement is three orders of magnitude
slower. So disable the use of prepared statements in this case.
(Since the query parameters are constant here, it would be nicer if we
could tell DBIx::Class to prepare a statement with those parameters
fixed. But I don't know an easy way to do so.)
