add initial implementation of cloudflare worker

serverless/cloudflare/worker.ts

@@ -0,0 +1,119 @@
+import { PMTiles, Source } from "../../js";
+
+interface Env {
+  BUCKET: R2Bucket;
+  CACHE_TTL: string;
+}
+
+interface CacheEntry {
+  lastUsed: number;
+  buffer: DataView;
+}
+
+export class LRUCache {
+  entries: Map<string, CacheEntry>;
+  counter: number;
+
+  constructor() {
+    this.entries = new Map<string, CacheEntry>();
+    this.counter = 0;
+  }
+
+  async get(
+    bucket: R2Bucket,
+    key: string,
+    offset: number,
+    length: number
+  ): Promise<[boolean, DataView]> {
+    let cacheKey = key + ":" + offset + "-" + length;
+    let val = this.entries.get(cacheKey);
+    if (val) {
+      val.lastUsed = this.counter++;
+      return [true, val.buffer];
+    }
+
+    let resp = await bucket.get(key, {
+      range: { offset: offset, length: length },
+    });
+    let a = await (resp as R2ObjectBody).arrayBuffer();
+    let d = new DataView(a);
+
+    this.entries.set(cacheKey, {
+      lastUsed: this.counter++,
+      buffer: d,
+    });
+    if (this.entries.size > 128) {
+      let minUsed = Infinity;
+      let minKey = undefined;
+      this.entries.forEach((val, key) => {
+        if (val.lastUsed < minUsed) {
+          minUsed = val.lastUsed;
+          minKey = key;
+        }
+      });
+      if (minKey) this.entries.delete(minKey);
+    }
+
+    return [false, d];
+  }
+}
+
+let worker_cache = new LRUCache();
+
+const TILE = new RegExp(
+  /^\/([0-9a-zA-Z\/!\-_\.\*\'\(\)]+)\/(\d+)\/(\d+)\/(\d+).pbf$/
+);
+
+export default {
+  async fetch(
+    request: Request,
+    env: Env,
+    context: ExecutionContext
+  ): Promise<Response> {
+    let url = new URL(request.url);
+
+    let match = url.pathname.match(TILE);
+
+    let subrequests = 1;
+
+    if (match) {
+      class TempSource {
+        getKey() {
+          return "";
+        }
+
+        async getBytes(offset: number, length: number) {
+          let result = await worker_cache.get(
+            env.BUCKET,
+            match![1] + ".pmtiles",
+            offset,
+            length
+          );
+
+          if (!result[0]) subrequests++;
+
+          return result[1];
+        }
+      }
+
+      let source = new TempSource();
+
+      let p = new PMTiles(source);
+      let entry = await p.getZxy(+match[2], +match[3], +match[4]);
+      if (entry) {
+        let tile = await env.BUCKET.get(match![1] + ".pmtiles", {
+          range: { offset: entry.offset, length: entry.length },
+        });
+
+        let headers = new Headers();
+        headers.set("Access-Control-Allow-Origin", "*");
+        headers.set("Content-Type", "application/x-protobuf");
+        headers.set("X-Pmap-Subrequests", subrequests.toString());
+        return new Response((tile as R2ObjectBody).body, {
+          headers: headers,
+        });
+      }
+    }
+    return new Response("Not Found");
+  },
+};