feat: add initial retry delay, and set default to 100ms (#336)

README.md

@@ -126,6 +126,9 @@ gaxios.request({url: '/data'}).then(...);
 
     // When there is no response, the number of retries to attempt. Defaults to 2.
     noResponseRetries?: number;
+
+    // The amount of time to initially delay the retry, in ms.  Defaults to 100ms.
+    retryDelay?: number;
   },
 
   // Enables default configuration for retries.

src/common.ts

@@ -116,8 +116,7 @@ export interface RetryConfig {
   currentRetryAttempt?: number;
 
   /**
-   * The amount of time to initially delay the retry.  Defaults to 100.
-   * @deprecated
+   * The amount of time to initially delay the retry, in ms.  Defaults to 100ms.
    */
   retryDelay?: number;
 

src/retry.ts

@@ -60,8 +60,11 @@ export async function getRetryConfig(err: GaxiosError) {
   }
 
   // Calculate time to wait with exponential backoff.
-  // Formula: (2^c - 1 / 2) * 1000
-  const delay = ((Math.pow(2, config.currentRetryAttempt) - 1) / 2) * 1000;
+  // If this is the first retry, look for a configured retryDelay.
+  const retryDelay = config.currentRetryAttempt ? 0 : config.retryDelay ?? 100;
+  // Formula: retryDelay + ((2^c - 1 / 2) * 1000)
+  const delay =
+    retryDelay + ((Math.pow(2, config.currentRetryAttempt) - 1) / 2) * 1000;
 
   // We're going to retry!  Incremenent the counter.
   err.config.retryConfig!.currentRetryAttempt! += 1;

test/test.retry.ts

@@ -275,4 +275,30 @@ describe('🛸 retry & exponential backoff', () => {
     });
     scope.done();
   });
+
+  it('should delay the initial retry by 100ms by default', async () => {
+    const scope = nock(url).get('/').reply(500).get('/').reply(200, {});
+    const start = Date.now();
+    await request({
+      url,
+      retry: true,
+    });
+    const delay = Date.now() - start;
+    assert.ok(delay > 100 && delay < 150);
+    scope.done();
+  });
+
+  it('should respect the retryDelay if configured', async () => {
+    const scope = nock(url).get('/').reply(500).get('/').reply(200, {});
+    const start = Date.now();
+    await request({
+      url,
+      retryConfig: {
+        retryDelay: 500,
+      },
+    });
+    const delay = Date.now() - start;
+    assert.ok(delay > 500 && delay < 550);
+    scope.done();
+  });
 });