Reuse CanonicalTile in TilePyramid

[asheemmamoowala]

Motivation

For over-zoomed and wrapped tiles, TilePyramid creates and maintains unique copies of the same canonical tile at multiple zooms and wraps. Each of these tiles needs a copy of the same raw data and has to re-parse it.

Reusing the tiles should allow caching more tiles and better performance when over-zooming.

For the ongoing custom vector sources, it would allow reusing the tile data without having to make a new fetchTile request.

Expectation

Raster tiles should be entirely reusable when over-zoomed. Once the raster data is parsed, the same bucket can be used for all zoom levels.

Vector tiles should reuse the raw data. The tile may hold separate buckets for different zoom levels, but may also be able to reuse the buckets when over-zooming.

cc @jfirebaugh @ChrisLoer @kkaefer

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[asheemmamoowala]

This is still useful to reduce memory consumption and improve performance

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.