Add Error Simulation to the Core

[michalpiszczek]

Currently, running error experiments on the frontends exhibits weird behavior because the core only supports perfect (volume/2) splits.

It should be possible to specify the error profile of an entire session (or perhaps individual split calls) in the frontends, and have the Core exhibit that behavior.

Example: I want the split error factor to be drawn from N(1, 0.01). When I go to split a 1 volume droplet, and draw 1.2 as the error factor, both the frontend and backend should now see a droplet with volume=0.6 and a droplet with volume=0.4 (see https://github.com/michalpiszczek/puddle/blob/error/src/python/examples/error_dilution.py for the frontend behavior).

Notes:

• One quick way to do this is having expected volumes be a parameter on split calls, and the Core will simply assume those passed values are correct and assign them to the resulting droplets.
• Gaussian error should be sufficient.
• Perhaps we should simulate error for input() as well.

[mwillsey]

4c9a41a at least adds splitting error.

puddle/src/python/tests/test_basic.py

Line 50 in 4c9a41a

with puddle.mk_session(split_error=0.1) as session: