Offline region download hits Mapbox API rate limits for sprites

[dpieri]

Platform: Android
Mapbox SDK version: 4.1.0

Steps to trigger behavior

1. Create a new offline region of any size using a style that relies on Mapbox-hosted sprites and tilesets.
2. Start downloading it.
3. Watch for error message Failed to load sprite: HTTP status code 429

Expected behavior

SDK does not trigger API rate limits.

Actual behavior

Sometimes, but not always, you see the 429 response, which must mean that the SDK is kicking off requests faster than the API allows.

Question

We are killing the offline download whenever an error occurs. For errors like this, does the SDK retry downloading the asset after reporting the 429 response, or is killing on the first error the correct way to handle them?

[1ec5]

I’m seeing the same thing on iOS, and it’s leading to a crash: #5827.

[1ec5]

As a temporary measure, we’ve increased the rate limit on non-tile resources (including sprites) on the server side.

[jfirebaugh]

Currently, a 429 response produces a response.error value of Error::Reason::Other, which is not retried.

We need to add an enumeration value to Response::Error::Reason representing a rate-limiting situation, include the value of any Retry-After response header somewhere (with a fallback to the non-standard x-rate-limit-reset header used by Mapbox APIs), and handle this situation in OnlineFileRequest by retrying according to the specified Retry-After value or a reasonable default.