Missing intervention definitions do not result in a 500 error

[rob-smallshire]

If an intervention definition is not found – for example because the interventions have not been installed – any attempt to run the simulator results in an error server side, but no error is apparently reported back to the client. I'd expect a 500 error of some sort.

$ pserve development.ini 
Starting server in PID 84091.
serving on http://0.0.0.0:6543
2015-11-02 21:20:07,060 ERROR [pyramid_debugtoolbar][waitress] Exception at http://0.0.0.0:6543/simulate
traceback url: http://0.0.0.0:6543/_debug_toolbar/exception?token=62275c7866355c783032795c7865325f4e2e5c786566325c78666127&tb=4428651208
multiprocessing.pool.RemoteTraceback: 
"""
Traceback (most recent call last):
  File "/Users/rjs/dev/bark-spider/bark_spider/intervention.py", line 40, in _parse_intervention
    cls = _interventions()[command]
KeyError: 'add'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/pool.py", line 119, in worker
    result = (True, func(*args, **kwds))
  File "/Users/rjs/dev/bark-spider/bark_spider/simulation/simulation.py", line 27, in run_simulation
    schedule = make_schedule(**params)
  File "/Users/rjs/dev/bark-spider/bark_spider/simulation/schedule.py", line 74, in make_schedule
    parse_interventions(StringIO(interventions)))
  File "/Users/rjs/dev/bark-spider/bark_spider/simulation/schedule.py", line 14, in __init__
    self._interventions = sorted(interventions, key=lambda i: i.time)
  File "/Users/rjs/dev/bark-spider/bark_spider/intervention.py", line 45, in _parse_intervention
    command, line))
ValueError: Unknown command "add" while parsing interventions. (full command=add 100 10)
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid_debugtoolbar/toolbar.py", line 192, in toolbar_tween
    response = _handler(request)
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid_debugtoolbar/panels/performance.py", line 57, in resource_timer_handler
    result = handler(request)
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid/tweens.py", line 21, in excview_tween
    response = handler(request)
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid/router.py", line 163, in handle_request
    response = view_callable(context, request)
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid/config/views.py", line 329, in attr_view
    return view(context, request)
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid/config/views.py", line 305, in predicate_wrapper
    return view(context, request)
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid/config/views.py", line 355, in rendered_view
    result = view(context, request)
  File "/Users/rjs/dev/virtualenvs/bark-spider/lib/python3.4/site-packages/pyramid/config/views.py", line 501, in _requestonly_view
    response = view(request)
  File "/Users/rjs/dev/bark-spider/bark_spider/views.py", line 42, in simulate_route
    lambda: _async_simulation(sim_params))
  File "/Users/rjs/dev/bark-spider/bark_spider/simulation_db.py", line 15, in add_results
    results = gen()
  File "/Users/rjs/dev/bark-spider/bark_spider/views.py", line 42, in <lambda>
    lambda: _async_simulation(sim_params))
  File "/Users/rjs/dev/bark-spider/bark_spider/views.py", line 24, in _async_simulation
    return result.get(timeout)
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/pool.py", line 599, in get
    raise self._value
ValueError: Unknown command "add" while parsing interventions. (full command=add 100 10)

[abingham]

The parsing-errors branch addresses this issue. I've decided to return HTTP/400 when there is a problem parsing interventions. Since I don't think we can distinguish between a mistyped intervention and one which is not installed, there's no condition under which I felt a 500 was correct.

Give it a try and let me know what you think.

[abingham]

Fixed at 5812938