[kylebarron]

Note

This PR was written by Claude (Claude Code), not by @kylebarron.

MosaicLayer passed renderSource the signal of the item's open. Both its docs example and the naip-mosaic example passed it on to each COGLayer's signal. That signal can't do what passing it suggests, and it can leave an item blank:

• It can't stop a layer's tile loads. deck.gl doesn't abort a tile once it has loaded, and renderSource only draws items whose open has finished.
• It can arrive already aborted. Say an item's open is aborted while more than maxRequests opens are in flight, and its getSource finishes anyway. Then deck.gl keeps the source, together with the aborted signal.
  • naip-mosaic's shared per-URL cache allows that: a later load's abort doesn't reject the promise that an earlier load started.
  • When the item is drawn again, its COGLayer gets the aborted signal, and every tile load aborts at once. The item stays blank for as long as its mosaic tile stays cached.

renderSource now gets only { source }. A COGLayer already aborts its loads that leave the view (#809). It aborts the rest when MosaicLayer evicts its item and the layer is finalized (#728).

Migration

Drop signal from renderSource's options. 0.10 already changes them from { data } to { source }.

// Before
renderSource: (item, { source, signal }) =>
  new COGLayer({ id: item.url, source, signal }),

// After
renderSource: (item, { source }) => new COGLayer({ id: item.url, source }),

Tests

• The bug, in deck.gl's LayerManager. The test reproduces it step by step:

  1. With maxRequests: 1, item A's open is aborted when A leaves the view while F's starts.
  2. A's getSource finishes anyway.
  3. A comes back into view.

  Before the fix, renderSource got an aborted signal. Now it gets { source }.

• A type test: renderSource's options are exactly { source?: SourceT }. It fails if signal is added back.

• The workspace typecheck passes, naip-mosaic included.

• In Chrome: naip-mosaic draws as before (924 NAIP items over Denver), with no new console messages.

🤖 Written by Claude Code

[kylebarron]

I see, so we only supply signal in getSource? Because renderSource shouldn't be loading headers (that's getSource's job), and then the tile reads happen inside the downstream layer (i.e. COGLayer)?

[kylebarron]

Note

This reply was written by Claude (Claude Code), not by @kylebarron.

Yes, exactly.

• getSource is the only async work MosaicLayer does for an item: opening its source, which reads the headers. So it's the only place a signal can cancel anything. deck.gl aborts it when it cancels the item's load: when the layer is removed, or when the item leaves view while more than maxRequests opens are in flight.
• renderSource is synchronous. It only builds layers from the opened source and loads nothing itself.
• The tile reads happen inside the layer it returns. COGLayer's inner TileLayer gives each tile load its own signal. That signal aborts when the tile leaves the view (feat(deck.gl-geotiff): coalesce COG tile reads by default #809) or the layer is removed (fix(deck.gl-raster): destroy tile textures when a raster layer is removed #728). COGLayer's own signal prop stays, for an app that wants to cancel all of a layer's tile loads itself.

🤖 Written by Claude Code

[kylebarron]

✅