BUG - Metakernel API times out for long durations

[pleasant-menlo]

Description of the issue

For time windows several months long, the metakernel API appears to time out, returning a "Service Unavailable" message.

Steps to reproduce the issue

Load the URL https://api.imap-mission.com/metakernel?start_time=813326400&end_time=825595200&list_files=true&file_types=leapseconds,spacecraft_clock,pointing_attitude,imap_frames,science_frames,planetary_ephemeris,ephemeris_reconstructed,planetary_constants

This is requesting a metakernel covering from 2025-10-10 to 2026-02-19.

It fails with a message {"message":"Service Unavailable"}

Expected vs Actual behavior

Expected a successful response with a list of kernel files.

[bryan-harter]

The problem was due to the fact that each DPS kernel has many gaps in it - every time there is a repointing, the API attempts to search all other DPS kernels for data, but only finds more gaps.

For now, we sped up the API by modifying how it searches the files. It's slightly slower for simple searches with relatively few gaps, but much much faster for many files + many gaps.

However, in the long run, what we'll do is ignore any gaps that occur at repointing times. That'll involve querying some files we get from the MOC so development will take a bit longer, and it'll be lower priority since the metakernel is sufficiently fast now.