Summary:
Importing a .grist document is implemented in a somewhat clunky way, in a multi-worker setup.
* First a random worker receives the upload, and updates Grist's various stores appropriately (database, redis, s3).
* Then a random worker is assigned to serve the document.
If the worker serving the document fails, there is a chance the it will end up assigned to the worker that handled its upload. Currently the worker will misbehave in this case. This diff:
* Ports a multi-worker test from test/home to run in test/s3, and adds a test simulating a bad scenario seen in the wild.
* Fixes persistence of any existing document checksum in redis when a worker is assigned.
* Adds a check when assigned a document to serve, and finding that document already cached locally. It isn't safe to rely only on the document checksum in redis, since that may have expired.
* Explicitly claims the document on the uploading worker, so this situation becomes even less likely to arise.
Test Plan: added test
Reviewers: dsagal
Reviewed By: dsagal
Subscribers: dsagal
Differential Revision: https://phab.getgrist.com/D3305
c4d3d7d3bb