subscribe test

src/blockstore/fragment-gateway.ts

@@ -171,7 +171,27 @@ export class FragmentGateway implements bs.Gateway {
     if (this.innerGW.subscribe) {
       return this.innerGW.subscribe(url, callback);
     } else {
-      return Result.Err(this.logger.Error().Msg("Subscribe not supported").AsError());
+      let lastData: Uint8Array | undefined = undefined;
+      let interval = 100;
+      const fetchData = async () => {
+        const result = await this.innerGW.get(url);
+        if (result.isOk()) {
+          const data = result.Ok();
+          if (!lastData || !data.every((value, index) => lastData && value === lastData[index])) {
+            lastData = data;
+            callback(data);
+            interval = 100; // Reset interval when data changes
+          } else {
+            interval *= 2; // Double the interval when data is unchanged
+          }
+        }
+        timeoutId = setTimeout(fetchData, interval);
+      };
+      let timeoutId = setTimeout(fetchData, interval);
+
+      return Result.Ok(() => {
+        clearTimeout(timeoutId);
+      });
     }
   }
 

tests/fireproof/all-gateway.test.ts

@@ -297,6 +297,51 @@ describe("noop Gateway", function () {
   });
 });
 
+describe("noop Gateway subscribe", function () {
+  let db: Database;
+
+  let metaStore: ExtendedStore;
+
+  let metaGateway: ExtendedGateway;
+
+  afterEach(async function () {
+    await db.close();
+    await db.destroy();
+  });
+  beforeEach(async function () {
+    db = new Database("test-gateway-" + Math.random().toString(36).substring(7));
+
+    // Extract stores from the loader
+    metaStore = (await db.blockstore.loader?.metaStore()) as unknown as ExtendedStore;
+
+    metaGateway = metaStore?.gateway;
+  });
+  it("should subscribe to meta Gateway", async function () {
+    const metaUrl = await metaGateway?.buildUrl(metaStore?._url, "main");
+    await metaGateway?.start(metaStore?._url);
+
+    if (metaGateway.subscribe) {
+      let resolve: () => void;
+      let didCall = false;
+      const p = new Promise<void>((r) => {
+        resolve = r;
+      });
+      const metaSubscribeResult = await metaGateway?.subscribe?.(metaUrl?.Ok(), async (data: Uint8Array) => {
+        const decodedData = new TextDecoder().decode(data);
+        expect(decodedData).toContain("[]");
+        didCall = true;
+        resolve();
+      });
+      expect(metaSubscribeResult?.Ok()).toBeTruthy();
+      const ok = await db.put({ _id: "key1", hello: "world1" });
+      expect(ok).toBeTruthy();
+      expect(ok.id).toBe("key1");
+      await p;
+      expect(didCall).toBeTruthy();
+    }
+  });
+});
+
 describe("Gateway", function () {
   let db: Database;
   // let carStore: ExtendedStore;