docs: spec for coalescing tile fetches through deck.gl getTileData#556
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docs: spec for coalescing tile fetches through deck.gl getTileData#556kylebarron wants to merge 6 commits into
kylebarron wants to merge 6 commits into
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Design for #273: a TileBatcher in deck.gl-raster that coalesces deck.gl's per-tile getTileData calls into one getMultiTileData (-> geotiff.fetchTiles) call per zoom level, plus a chunkd request-scheduler middleware in geotiff so maxRequests bounds actual concurrent HTTP requests. No public fetchTiles API change; no loaders.gl dependency in geotiff. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
A minimal slot-acquisition contract — `acquire(signal?): Promise<() => void>` where an abort while queued drops the request without firing it — plus: - `limitFetch(fetch, limiter)`: wraps a Source.fetch to hold a slot for its duration, forwarding the call's signal to acquire(). - `Semaphore`: a FIFO concrete impl. - `defaultLimiterForOrigin(url)`: returns a per-origin shared Semaphore (`maxRequests = 6`) cached across calls, so multiple sources targeting the same host (multiple GeoTIFF.fromUrl, plus future Zarr etc.) share one cap — the relevant constraint is the browser's HTTP/1.1 per-origin connection limit, which is global to the page, not per-layer. No loaders.gl / @chunkd dependency; geotiff stays self-contained. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
When supplied, the data source's fetch is wrapped via limitFetch so every tile-data and mask HTTP request is gated by the limiter. Header/metadata reads are not gated — small, mostly at open time, served from the header cache. GeoTIFF.fromUrl defaults the limiter to defaultLimiterForOrigin(url) — so two `fromUrl` calls (or any other source-level caller) targeting the same origin automatically share one cap. Pass an explicit limiter to override; pass `null` to disable gating. fetchTile / fetchTiles / coalesceRanges are untouched. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The cap that matters is the browser's HTTP/1.1 concurrent-connections- per-origin limit (~6 on Chrome), which is *global to the page* — not per-layer. The earlier design had RasterTileLayer create a layer-scoped RequestScheduler, which can't enforce that cap across multiple layers sharing an origin (two COGLayers on one S3 bucket would each get 6 slots → 12 in flight → browser queues, and stale-after-pan requests block fresh ones). Pivot: - Decouple concurrency limiting from multi-tile coalescing. They were always two concerns; the spec now treats them as independent pieces that can ship and be reasoned about separately. - Move the limiter to the source layer (geotiff). GeoTIFF.fromUrl defaults its concurrencyLimiter to defaultLimiterForOrigin(url), a shared per-origin Semaphore (max=6). Two `fromUrl` calls (or any other source-level caller, future Zarr included) targeting the same origin automatically share one cap, zero setup. - Drop the chunkd SourceMiddleware framing; gate just the data source's .fetch via limitFetch. No SourceView, no chunkd-vs-cogeotiff Source- type cast. - Drop the loaders.gl RequestScheduler adapter from deck.gl-raster. The layer no longer owns or threads a limiter. - Add `signal` to ConcurrencyLimiter.acquire so queued aborts drop rather than fire stale requests after a pan. The TileBatcher work (the deck.gl-raster half) is unchanged in spirit but no longer creates a limiter; it just runs the batcher and sets the inner TileLayer's maxRequests: 0. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Like fetchTiles, but a single missing tile or a single tile's decode
failure becomes a { error } entry in its slot rather than throwing. A
network-level failure inside a coalesced range still rejects the whole
call (those bytes are gone for every tile in the merged range). Composes
the existing coalesced byte-fetch + per-tile assembleTile pieces; adds a
collect-not-throw variant of fetchCogBytesMultiple. New method on
GeoTIFF + Overview. SettledTile type re-exported from the package.
For the deck.gl batched-fetch path so one bad tile can't blank a viewport.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Buffers per-item fetch() calls and dispatches one batched call per group key on a setTimeout(_, 0); per-item Error distribution; composite "abort-when-all" signal; finalize() rejects what's buffered. Pure coalescer — no limiter ownership, no scheduler — that's the source layer's concern. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Design for #273: a TileBatcher in deck.gl-raster that coalesces deck.gl's per-tile getTileData calls into one getMultiTileData (-> geotiff.fetchTiles) call per zoom level, plus a chunkd request-scheduler middleware in geotiff so maxRequests bounds actual concurrent HTTP requests. No public fetchTiles API change; no loaders.gl dependency in geotiff.