Abort during delay

source/exponential-backoff.ts

@@ -263,7 +263,31 @@ export class ExponentialBackoff {
 
             // Wait before going to the next attempt
             const delay = this.#calculateDelay(this.#options, attempt);
-            await new Promise((resolve) => setTimeout(resolve, delay));
+
+            // Wait for the delay or the abort signal
+            await new Promise((resolve, reject) => {
+                // Set a timeout to resolve the promise after the delay
+                let timeout: ReturnType<typeof setTimeout>;
+
+                // Handle the abort signal
+                const abortHandler = () => {
+                    clearTimeout(timeout);
+                    abortController.signal.removeEventListener('abort', abortHandler);
+                    reject(new ExponentialBackoffStoppedRetriesError(abortController.signal.reason));
+                };
+
+                // Handle the timeout
+                const timeoutHandler = () => {
+                    abortController.signal.removeEventListener('abort', abortHandler);
+                    resolve(undefined);
+                };
+
+                // Set the timeout
+                timeout = setTimeout(timeoutHandler, delay);
+
+                // Add the abort handler to the abort signal
+                abortController.signal.addEventListener('abort', abortHandler);
+            })
 
             attempt++;
         }

test/exponential-backoff.test.ts

@@ -299,6 +299,49 @@ const testExponentialBackoffRunAbortedStringCreatesError = async (): Promise<voi
     expect(abortAndThrowStringFn).not.toHaveResolved();
 };
 
+/**
+ * Tests that the delay is aborted when the abort signal is activated.
+ */
+const testExponentialBackoffRunDelayAbortedWhenAbortSignal = async (): Promise<void> => {
+    vi.useFakeTimers();
+
+    try {
+        let abort: (reason: unknown) => void;
+
+        const taskFn = vi.fn(async ({ stopRetries }) => { 
+            abort = stopRetries;
+            throw new Error('error message');
+        });
+
+        // Start the exponential backoff and wait for it to complete
+        const result = ExponentialBackoff.run(taskFn, () => {}, {
+            baseDelay: 1000,
+            jitter: 0,
+            maxAttempts: 0,
+        });
+
+        // Advance the timer by 500 (mid delay)
+        await vi.advanceTimersByTimeAsync(500);
+
+        // Make sure the abort function is defined (That the taskFn was called)
+        if (!abort!) {
+            throw new Error('abort is not defined');
+        }
+
+        // Check that the rsult is still pending
+        expect(result).not.resolves;
+        expect(abort).toBeDefined();
+
+        // Abort the exponential backoff
+        abort?.(new Error('exponential backoff aborted'));
+
+        // Expect the result to be rejected with an ExponentialBackoffStoppedRetriesError
+        await expect(result).rejects.toThrow(ExponentialBackoffStoppedRetriesError);
+    }
+    finally {
+        vi.useRealTimers();
+    }
+};
 /**
  * Tests the {@link ExponentialBackoff.from} factory and subsequent instance {@link ExponentialBackoff.run}
  * as an alternative to the static helper.
@@ -617,6 +660,7 @@ const runTests = async (): Promise<void> => {
     test('ExponentialBackoff: succeeds and aborts with abort signal', testExponentialBackoffRunSuccessAndAbortSignal);
     test('ExponentialBackoff: aborts with abort signal', testExponentialBackoffRunWithAbortSignal);
     test('ExponentialBackoff: aborts with aborted string creates error', testExponentialBackoffRunAbortedStringCreatesError);
+    test('ExponentialBackoff: aborts with abort signal, skipping delay', testExponentialBackoffRunDelayAbortedWhenAbortSignal);
     test('ExponentialBackoff: works via from and instance run', testExponentialBackoffFromAndInstanceRun);
     test('ExponentialBackoff: retries indefinitely when maxAttempts is 0', testExponentialBackoffRetriesIndefinitelyWhenMaxAttemptsIsZero);
     test('ExponentialBackoff: increases delay exponentially between attempts', testExponentialBackoffIncreasesDelayExponentially);