eclipse#220 backoff

Signed-off-by: Emily Jiang <[email protected]>

api/src/main/java/org/eclipse/microprofile/faulttolerance/Retry.java

@@ -45,6 +45,9 @@
  * @see #maxRetries()
  * @see #delay()
  * @see #delayUnit()
+ * @see #delayFactor()
+ * @see #maxDelay()
+ * @see #maxDelayUnit()
  * @see #maxDuration()
  * @see #durationUnit()
  * @see #jitter()
@@ -87,6 +90,29 @@
     @Nonbinding
     ChronoUnit delayUnit() default ChronoUnit.MILLIS;
 
+    /**
+     * The delay factor for {@link #delay}, which exponentially backing off to the maxDelay and multiplying successive delays by the delayFactor. Defaults to 1 if not set.
+     *
+     * @return the delay unit
+     */
+    @Nonbinding
+    double delayFactor() default 1;
+
+    /**
+     * The max delay. Defaults to 60000.
+     * @return the max delay
+     */
+    @Nonbinding
+    long maxDelay() default 60000;
+
+      /**
+     * The maxDelay unit for {@link #maxDelay}. Defaults to {@link java.time.temporal.ChronoUnit#MILLIS} if not set.
+     *
+     * @return the duration unit
+     */
+    @Nonbinding
+    ChronoUnit maxDelayUnit() default ChronoUnit.MILLIS;
+
     /**
      * The max duration. The max duration must be greater than the delay duration if set. 0 means not set.
      *

spec/src/main/asciidoc/retry.asciidoc

@@ -26,13 +26,16 @@ The `Retry` policy allows to configure :
 * `maxRetries`: the maximum retries
 * `delay`: delays between each retry
 * `delayUnit`: the delay unit
+* `delayFactor`: the delay factor, which exponentially backs off to the maxDelay and multiplying successive delays by the delayFactor
+* `maxDelay`: the maximum delay between the retries
+* `maxDelayUnit`: the maximum delay unit
 * `maxDuration`: maximum duration to perform the retry for.
-* `durationUnit`: duration unit
+* `durationUnit`: maximum duration unit
 * `jitter`: the random vary of retry delays
 * `jitterDelayUnit`: the jitter unit
 * `retryOn`: specify the failures to retry on
 * `abortOn`: specify the failures to abort on
-
+The delay between the retries will be affected by `delay`, `jitter` and `delayFactor`. After applying the policies, if the delay exceeds the `maxDelay`, the value of `maxDelay` will be used.
 === Retry usage
 
 `@Retry` can be applied to the class or method level.