feat: retry logic catches thrown errors (#774)

docs/generated/changelog.html

@@ -12,6 +12,7 @@ <h1>Agent-JS Changelog</h1>
     <section>
       <h2>Version x.x.x</h2>
       <ul>
+        <li>feat: retry logic will catch and retry for thrown errors</li>
         <li>
           feat!: adds certificate logic to decode subnet and node key paths from the hashtree.
           Changes the interface for `lookup_path` to allow returning a HashTree, but also constrains

packages/agent/src/agent/http/http.test.ts

@@ -811,3 +811,20 @@ describe('default host', () => {
     }
   });
 });
+
+test('retry requests that fail due to a network failure', async () => {
+  const mockFetch: jest.Mock = jest.fn(() => {
+    throw new Error('Network failure');
+  });
+
+  const agent = new HttpAgent({ host: HTTP_AGENT_HOST, fetch: mockFetch });
+  try {
+    await agent.call(Principal.managementCanister(), {
+      methodName: 'test',
+      arg: new Uint8Array().buffer,
+    });
+  } catch (error) {
+    // One try + three retries
+    expect(mockFetch.mock.calls.length).toBe(4);
+  }
+});

packages/agent/src/agent/http/index.ts

@@ -365,7 +365,20 @@ export class HttpAgent implements Agent {
   }
 
   private async _requestAndRetry(request: () => Promise<Response>, tries = 0): Promise<Response> {
-    const response = await request();
+    let response: Response;
+    try {
+      response = await request();
+    } catch (error) {
+      if (this._retryTimes > tries) {
+        console.warn(
+          `Caught exception while attempting to make request:\n` +
+            `  ${error}\n` +
+            `  Retrying request.`,
+        );
+        return await this._requestAndRetry(request, tries + 1);
+      }
+      throw error;
+    }
     if (response.ok) {
       return response;
     }