pyzmq recommends the use of a single context for all objects in the same
application:
https://pyzmq.readthedocs.io/en/latest/api/zmq.html#zmq.Context.instance

More importantly, each context creates at least one thread, resulting in
a lot of threads with a lot of open file descriptors. This path reduces
that number by quite a bit.

Code refactoring in Container management

See merge request !54

Add a container runtime that doesn't create containers, but can still
launch commands.

That should make it possible, once we figure out how to change it in the
configuration, to actually run the NRM without a setuid binary.

Extract the container runtime interface from the container manager, and
use a hierarchy of classes to enforce a runtime interface that makes
sense.

This will allow us to create alternative runtime implementations without
major changes to the container manager code.

Missing checks in aci resulted in features absent from the manifest to
be counted as enabled.

Just to make it easy to debug binding issues.

!27 replaced the resource field of the `container` named tuple by a
dictionary. Restore the old type, a `resources` named tuple and make
sure to propagate this across all the code.

Refactor the container creation code to isolate the building/retrieving
of a container namedtuple out of the core container creation code.

This simplifies quite a bit the different branches of this code, and
makes the core create method almost entirely dedicated to just launching
a command.

Some of these commands prefix were in a bit of a weird order. In
particular, it makes sense to have perfwrapper at the end.

!27 caused the perfwrapper to only be activated for the command that
creates a container, and never for the other commands launched in an
already running container. This patch restore this feature.

The container creation code was starting to repeat the same logic for
testing that a container manifest was enabling a specific feature.

Instead we add a method to the image manifest to check for that.
Also adds tests for that feature.

Bump CI.

See merge request !56

Refactors Nix code to be even simpler.

See merge request !53

nix-shell -A nrm for a nrm development environment.
nix-shell -A test for an versioned integration test environment.
nix-build -A <tab> to build a package from the versioned test environment.
nix-shell -A <tab> for other shell options.
nix-build -A <tab> for other build options.

Resolve "Tests are too permissive -> master broken"

Closes #28

See merge request !52

The last merge changed the API visual style to increase readability.

The manual merging was not done in a proper way however, and some of the
changes from its previous merges were reverted. This commit fixes this.

[refactor] messaging code style + cmd_listen application_uuid relaxing

See merge request !48

container.

This commit does two things:
- re-indents the message schema to be more readable
- lets `cmd listen --filter` print any incoming message, without
discriminating on container_uuid. This makes cmd listen usable until
a proper application_uuid management is written into nrm.

[fix] stylecheck issues

See merge request !50

Some inconsistencies in the CI let a merge request go through without
stylechecking.

[ci] Removes branch filtering based on `wip-*`.

See merge request !49

Aggregative Downstream API integration and Support for Process/Task pinning

See merge request !47

Made necesseary fixes required to make the aggregative downstream api
integration to work with the new downstream messaging layer.

Also,fixed the case where daemon crashed when an application message
(from libnrm using pmpi) was received after container was killed

run_policy on all containers removed as the controller no longer has
application manager info

Any other refactoring and fixes required (check merge request
discussion)

See Issues #13, #20 and Merge !41

Added support for pinning process/task to a core. This is important for
allowing the use of power policies that use contextual information from an
application phase and use it for computing frequency levels for the next phase.
In absence of process/task pinning, the contextual information obtained does
not serve any value as it is not representative of application phase behavior
on a core as the processes and task can migrate during the next phase.

See Issue #20

Fixes NRM not returning the first N resources (cpu and memory). This
is important for reproducibility and reducing variation

Fixed the interaction of the multi-node support feature (#17) with the new
messaging layer feature. Also, added any other fixes required to make the
libnrm work with the Aggregative downstream API

Adds support for aggregation of phase context information for an
application. The damper value (in nanoseconds in the manifest file)
decides the minimum phase length for which the phase context
information is sent to the NRM (implemented in 'libnrm' repo
[See Issue 2]). This will limit the number of msgs sent to the NRM.

See Issue #13

Refactored diff calculation code to work without needing changes in
coolr module (Patch for Commit 36401a84)

[fix] Fixes `cmd listen --filter` for power messages.

See merge request !46

[feature] Adds a --filter option to `cmd` for pretty-printing.

See merge request !44

The option accepts a message type and prints the values in the csv
format:
msgtype, time, payload if the --filter option is recognized
msgtype, time otherwise
The print is force-flushed on stdout.
This switches CI to the "refactored" CI identifier at argotests/tests

Integration power

See merge request !45