WIP: async awesomeness

[bbangert]

Description:

WIP: NOT READY FOR MERGE YET

This replaces the primary mechanism by which HASS runs.

The existing architecture exposes 3 core.py API objects, EventBus, StateMachine, and ServiceRegistry. These are called from a variety of threads and are all blocking calls that attempt to acquire per-object locks to fully execute.

This change retains the existing thread-safe blocking API for use by all components, as well as the blocking nature of component setup. However, it starts up an asyncio event loop on start, which is where the actual work is done. The thread-safe API calls schedule the async API variant version into the event loop, then blocks waiting until it has run to completion.

EventBus registrations that are marked as coroutines run on the event loop and may directly run async versions of the appropriate API's. To retain similar call characteristics as before, EventBus's async_fire schedules coroutines to run later on the event loop while sending non-coroutines to the thread-pool as before. This does mean that coroutine listeners are guaranteed to run after all listeners were located, while non-coroutines may start executing immediately in the other thread.

This WIP uses Python 3.4.4 functionality as a proving ground for the approach, using earlier 3.4 should be fine with a backported function or two for asyncio features needed (such as run_coroutine_threadsafe).

[balloobbot]

farcy v1.1

• 1: F401 'asyncio' imported but unused

[balloob]

I really like this and I think this will be great change.

I looked at the first failing test, tests/test_bootstrap.py::TestBootstrap::test_platform_specific_config_validation and that seems to be because we pass the wrong arguments to MockPlatform on line 283. It should be MockPlatform(platform_schema=platform_schema)). However, that seems to fail while waiting for the result of setting up listening for a discovery:

Traceback (most recent call last):
  File "/Users/paulus/dev/python/home-assistant/homeassistant/bootstrap.py", line 102, in _setup_component
    result = component.setup(hass, config)
  File "/Users/paulus/dev/python/home-assistant/homeassistant/components/switch/__init__.py", line 76, in setup
    component.setup(config)
  File "/Users/paulus/dev/python/home-assistant/homeassistant/helpers/entity_component.py", line 63, in setup
    component_platform_discovered)
  File "/Users/paulus/dev/python/home-assistant/homeassistant/helpers/discovery.py", line 60, in listen_platform
    hass.bus.listen(EVENT_PLATFORM_DISCOVERED, discovery_platform_listener)
  File "/Users/paulus/dev/python/home-assistant/homeassistant/core.py", line 340, in listen
    future.result()
[…snip…]

I'm down to help with fixing the tests and the other issues. Shall we move the branch to the HA repo so we can both push to it?

[balloob]

btw, I have added the fix for the bootstrap test to #3196 as it contained some other misc fixes.