Added ConcurrentTileLoader to facilitate simultaneous loading of tile…

… data from multiple data sources

Signed-off-by: Tim Deubler <[email protected]>

packages/core/src/loaders/ConcurrentTileLoader.ts

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2019-2024 HERE Europe B.V.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * License-Filename: LICENSE
+ */
+
+import TileLoader from './TileLoader';
+import {Tile} from '../tile/Tile';
+
+type Callback = (data: any) => void;
+
+class ConcurrentTileLoader implements TileLoader {
+    private loaders: { [key: string]: TileLoader };
+    private length: number = 0;
+
+    constructor(loaders: { [key: string]: TileLoader }) {
+        this.loaders = loaders;
+        for (let key in loaders) this.length++;
+    };
+
+    abort(tile: Tile): void {
+        let {loaders} = this;
+        for (let key in loaders) {
+            loaders[key].abort(tile);
+        }
+    }
+
+    load(tile: Tile, success: Callback, error: Callback): void {
+        let {loaders, length} = this;
+        const data = {};
+
+        for (let key in loaders) {
+            const loader = loaders[key];
+            loader.load(tile, (d) => {
+                data[key] = d;
+                if (!--length) {
+                    success(data);
+                }
+            }, (e) => {
+                length = -1;
+                this.abort(tile);
+                error(e);
+            });
+        }
+    }
+};
+
+export {ConcurrentTileLoader};