Drop retry strategy and up cache time

inc/HttpClient/HttpClient.php

@@ -124,7 +124,7 @@ public static function retry_decider( int $retries, RequestInterface $request, ?
 
 		$should_retry = false;
 
-		if ( $response && $response->getStatusCode() >= 500 ) {
+		if ( $response && ( $response->getStatusCode() >= 500 || $response->getStatusCode() === 429 ) ) {
 			$should_retry = true;
 		}
 
@@ -143,9 +143,15 @@ public static function retry_decider( int $retries, RequestInterface $request, ?
 	 * @return int Number of milliseconds to delay.
 	 */
 	public static function retry_delay( int $retries, ?ResponseInterface $response ): int {
-		// Be default, implement a linear backoff strategy.
-		$retry_after = $retries;
-
+		// Implement an exponential backoff strategy with jitter, with the delay capped at 10s and a minimum of 1s.
+		// Full Jitter taken from https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/.
+		// Given we only retry 3 times, this will really never exceed 8s.
+		$retry_after_without_jitter = min( 10, 1 * pow( 2, $retries ) );
+		$retry_after = wp_rand( 1, $retry_after_without_jitter );
+
+		// If the response has a Retry-After header, use that value.
+		// If the value is a date, calculate the difference from now.
+		// If the value is a number, use that as the delay.
 		if ( $response instanceof ResponseInterface && $response->hasHeader( 'Retry-After' ) ) {
 			$retry_after = $response->getHeaderLine( 'Retry-After' );
 
@@ -154,6 +160,7 @@ public static function retry_delay( int $retries, ?ResponseInterface $response )
 			}
 		}
 
+		// Convert it to milliseconds.
 		$retry_after_ms = (int) $retry_after * 1000;
 		return apply_filters( 'remote_data_blocks_http_client_retry_delay', $retry_after_ms, $retries, $response );
 	}