Transport Take Home Exercise
This repository contains source code for Sam Szuflita's application to Indigo Ag.
This code was tested against Python 3.9.4 and Flask 2.0.1. Other tools and dependencies are described in requirements.txt.
Commands
Run debug server:
FLASK_APP=app.main flask run
Run integration tests (Note: these use a rolling window of 1 second):
pytest
get.http and post.http contain sample HTTP requests that I used while developing this solution.
Source overview
All relevant logic for this application lives in main.py. At a high level, the application stores a list of (timestamp, value) tuples and a cached sum per key. On POST, a new value is appended to the appropriate list and the sum is updated. On GET, the app removes any values that are more than window old (default is 1 hour) and subtracts their value from the cached sum.
This design optimizes for a case in which the POST operation is more performance sensitive than the GET. The POST requires a constant number of operations, while a GET requires reading through N values to purge them. In my experience, it is much more likely that this kind of POST will wind up in a hot loop in code, and the GET will mostly happen when we are loading a dashboard. Given this, I chose to remove stale values in the GET request.