fix: preserve externally provided earcut pool (#218) (#219)

Author: MarkusTomio

packages/deck.gl-geoarrow/src/layers/solid-polygon-layer.ts

@@ -199,6 +199,7 @@ export class GeoArrowSolidPolygonLayer<
     triangles: Uint32Array | null;
     earcutWorkerPool: Pool<FunctionThread> | null;
     earcutWorkerRequest: Promise<string> | null;
+    ownsEarcutWorkerPool: boolean;
   };
 
   override initializeState(_context: LayerContext): void {
@@ -211,6 +212,7 @@ export class GeoArrowSolidPolygonLayer<
           ? null
           : fetch(this.props.earcutWorkerUrl).then((resp) => resp.text()),
       earcutWorkerPool: this.props.earcutWorkerPool || null,
+      ownsEarcutWorkerPool: false,
     };
   }
 
@@ -243,14 +245,17 @@ export class GeoArrowSolidPolygonLayer<
         this.props.earcutWorkerPoolSize || 1,
       );
       this.state.earcutWorkerPool = pool;
+      this.state.ownsEarcutWorkerPool = true;
       return this.state.earcutWorkerPool;
     } catch (_err) {
       return null;
     }
   }
 
   override async finalizeState(_context: LayerContext): Promise<void> {
-    await this.state?.earcutWorkerPool?.terminate();
+    if (this.state?.ownsEarcutWorkerPool) {
+      await this.state?.earcutWorkerPool?.terminate();
+    }
     console.log("terminated");
   }
 

packages/deck.gl-geoarrow/tests/solid-polygon-layer.test.ts

@@ -0,0 +1,24 @@
+import type { FunctionThread, Pool } from "threads";
+import { describe, expect, it, vi } from "vitest";
+import { GeoArrowSolidPolygonLayer } from "../src/layers/solid-polygon-layer.js";
+
+describe("GeoArrowSolidPolygonLayer earcut worker pool lifecycle", () => {
+  it("does not terminate an externally provided worker pool", async () => {
+    const terminate = vi.fn(async () => {});
+
+    const externalPool = {
+      terminate,
+    } as unknown as Pool<FunctionThread>;
+
+    const layer = new GeoArrowSolidPolygonLayer({
+      id: "test-layer",
+      data: null as never,
+      earcutWorkerPool: externalPool,
+    });
+
+    layer.initializeState({} as never);
+    await layer.finalizeState({} as never);
+
+    expect(terminate).not.toHaveBeenCalled();
+  });
+});