Implements support for Nix's new Perl bindings[1]. The current state
basically does `openStore()`, but always uses `auto` and doesn't support
stores at other URIs.
Even though the stores are cached inside the Perl implementation, I
decided to instantiate those once in the Nix helper module. That way
store openings aren't cluttered across the entire codebase. Also, there
are two stores used later on - MACHINE_LOCAL_STORE for `auto`,
BINARY_CACHE_STORE for the one from `store_uri` in `hydra.conf` - and
using consistent names should make the intent clearer then.
This doesn't contain any behavioral changes, i.e. the build product
availability issue from #1352 isn't fixed. This patch only contains the
migration to the new API.
[1] https://github.com/NixOS/nix/pull/9863
There's currently no automatic recovery for disconnected databases in
the evaluator. This means if the database is ever temporarily
unavailable, hydra-evaluator will sit and spin with no work
accomplished.
If this condition is caught, the daemon will exit and systemd will be
responsible for resuming the service.
In the past, jobsets which are automatically evaluated are evaluated
regularly, on a schedule. This schedule means a new evaluation is
created every checkInterval seconds (assuming something changed.)
This model works well for architectures where our build farm can
easily keep up with demand.
This commit adds a new type of evaluation, called ONE_AT_A_TIME, which
only schedules a new evaluation if the previous evaluation of the
jobset has no unfinished builds.
This model of evaluation lets us have 'low-tier' architectures.
For example, we could now have a jobset for ARMv7l builds, where
the buildfarm only has a single, underpowered ARMv7l builder.
Configuring that jobset as ONE_AT_A_TIME will create an evaluation
and then won't schedule another evaluation until every job of
the existing evaluation is complete.
This way, the cache will have a complete collection of pre-built
software for some commits, but the underpowered architecture will
never become backlogged in ancient revisions.
Building on macOS with the latest nixpkgs master and NixOS/nixpkgs#77147
fails. It seems some `std::experimental` (optional) for instance are
not available as `experimental`, but are in `std`. Also `toJSON` is
missing for `atomic< unsigned long long >`.
* The "Jobset" page now shows when evaluations are in progress (rather
than just pending).
* Restored the ability to do a single evaluation from the command line
by doing "hydra-evaluator <project> <jobset>".
* Fix some consistency issues between jobset status in PostgreSQL and
in hydra-evaluator. In particular, "lastCheckedTime" was never
updated internally.
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.
