Add support for Fallback.onFailedAttempt.

Fixes #248.

Author: jhalterman

src/main/java/net/jodah/failsafe/Fallback.java

@@ -16,13 +16,17 @@
 package net.jodah.failsafe;
 
 import net.jodah.failsafe.event.ExecutionAttemptedEvent;
-import net.jodah.failsafe.function.*;
+import net.jodah.failsafe.function.CheckedConsumer;
+import net.jodah.failsafe.function.CheckedFunction;
+import net.jodah.failsafe.function.CheckedRunnable;
+import net.jodah.failsafe.function.CheckedSupplier;
+import net.jodah.failsafe.internal.EventListener;
 import net.jodah.failsafe.internal.util.Assert;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 
-import static net.jodah.failsafe.Functions.*;
+import static net.jodah.failsafe.Functions.toFn;
 
 /**
  * A Policy that handles failures using a fallback function or result.
@@ -42,6 +46,7 @@ public class Fallback<R> extends FailurePolicy<Fallback<R>, R> {
   private final CheckedFunction<ExecutionAttemptedEvent, R> fallback;
   private final CheckedFunction<ExecutionAttemptedEvent, CompletableFuture<R>> fallbackStage;
   private boolean async;
+  private EventListener failedAttemptListener;
 
   private Fallback() {
     this(null, null, false);
@@ -211,6 +216,17 @@ public boolean isAsync() {
     return async;
   }
 
+  /**
+   * Registers the {@code listener} to be called when an execution attempt fails. You can also use {@link
+   * #onFailure(CheckedConsumer) onFailure} to determine when the execution attempt fails <i>and</i> and the fallback
+   * result fails.
+   * <p>Note: Any exceptions that are thrown from within the {@code listener} are ignored.</p>
+   */
+  public Fallback<R> onFailedAttempt(CheckedConsumer<? extends ExecutionAttemptedEvent<R>> listener) {
+    failedAttemptListener = EventListener.ofAttempt(Assert.notNull(listener, "listener"));
+    return this;
+  }
+
   /**
    * Returns the applied fallback result.
    */
@@ -229,6 +245,6 @@ CompletableFuture<R> applyStage(R result, Throwable failure, ExecutionContext co
 
   @Override
   public PolicyExecutor toExecutor(AbstractExecution execution) {
-    return new FallbackExecutor(this, execution);
+    return new FallbackExecutor(this, execution, failedAttemptListener);
   }
 }

src/main/java/net/jodah/failsafe/FallbackExecutor.java

@@ -15,6 +15,7 @@
  */
 package net.jodah.failsafe;
 
+import net.jodah.failsafe.internal.EventListener;
 import net.jodah.failsafe.util.concurrent.Scheduler;
 
 import java.util.concurrent.*;
@@ -24,8 +25,11 @@
  * A PolicyExecutor that handles failures according to a {@link Fallback}.
  */
 class FallbackExecutor extends PolicyExecutor<Fallback> {
-  FallbackExecutor(Fallback fallback, AbstractExecution execution) {
+  private final EventListener failedAttemptListener;
+
+  FallbackExecutor(Fallback fallback, AbstractExecution execution,   EventListener failedAttemptListener) {
     super(fallback, execution);
+    this.failedAttemptListener = failedAttemptListener;
   }
 
   /**
@@ -92,4 +96,11 @@ protected Supplier<CompletableFuture<ExecutionResult>> supplyAsync(
       return postExecuteAsync(result, scheduler, future);
     });
   }
+
+  @Override
+  protected ExecutionResult onFailure(ExecutionResult result) {
+    if (failedAttemptListener != null)
+      failedAttemptListener.handle(result, execution);
+    return result;
+  }
 }

src/main/java/net/jodah/failsafe/RetryPolicy.java

@@ -229,7 +229,9 @@ public RetryPolicy<R> onAbort(CheckedConsumer<? extends ExecutionCompletedEvent<
   }
 
   /**
-   * Registers the {@code listener} to be called when an execution attempt fails.
+   * Registers the {@code listener} to be called when an execution attempt fails. You can also use {@link
+   * #onFailure(CheckedConsumer) onFailure} to determine when the execution attempt fails <i>and</i> and all retries
+   * have failed.
    * <p>Note: Any exceptions that are thrown from within the {@code listener} are ignored.</p>
    */
   public RetryPolicy<R> onFailedAttempt(CheckedConsumer<? extends ExecutionAttemptedEvent<R>> listener) {

src/main/java/net/jodah/failsafe/RetryPolicyExecutor.java

@@ -41,10 +41,10 @@ class RetryPolicyExecutor extends PolicyExecutor<RetryPolicy> {
   private volatile long delayNanos = -1;
 
   // Listeners
-  private EventListener abortListener;
-  private EventListener failedAttemptListener;
-  private EventListener retriesExceededListener;
-  private EventListener retryListener;
+  private final EventListener abortListener;
+  private final EventListener failedAttemptListener;
+  private final EventListener retriesExceededListener;
+  private final EventListener retryListener;
 
   RetryPolicyExecutor(RetryPolicy retryPolicy, AbstractExecution execution, EventListener abortListener,
     EventListener failedAttemptListener, EventListener retriesExceededListener, EventListener retryListener) {
@@ -148,6 +148,9 @@ else if (postResult != null) {
   @Override
   @SuppressWarnings("unchecked")
   protected ExecutionResult onFailure(ExecutionResult result) {
+    if (failedAttemptListener != null)
+      failedAttemptListener.handle(result, execution);
+
     failedAttempts++;
     long waitNanos = delayNanos;
 
@@ -175,10 +178,6 @@ protected ExecutionResult onFailure(ExecutionResult result) {
     boolean completed = isAbortable || !shouldRetry;
     boolean success = completed && result.isSuccess() && !isAbortable;
 
-    // Call attempt listeners
-    if (failedAttemptListener != null && !success)
-      failedAttemptListener.handle(result, execution);
-
     // Call completion listeners
     if (abortListener != null && isAbortable)
       abortListener.handle(result, execution);

src/test/java/net/jodah/failsafe/ListenersTest.java

@@ -39,6 +39,7 @@ public class ListenersTest {
   Waiter waiter;
 
   // RetryPolicy listener counters
+  ListenerCounter rpHandle = new ListenerCounter();
   ListenerCounter rpAbort = new ListenerCounter();
   ListenerCounter rpFailedAttempt = new ListenerCounter();
   ListenerCounter rpRetriesExceeded = new ListenerCounter();
@@ -54,6 +55,7 @@ public class ListenersTest {
   ListenerCounter cbFailure = new ListenerCounter();
 
   // Fallback listener counters
+  ListenerCounter fbFailedAttempt = new ListenerCounter();
   ListenerCounter fbSuccess = new ListenerCounter();
   ListenerCounter fbFailure = new ListenerCounter();
 
@@ -99,6 +101,7 @@ void beforeMethod() {
     cbSuccess.reset();
     cbFailure.reset();
 
+    fbFailedAttempt.reset();
     fbSuccess.reset();
     fbFailure.reset();
 
@@ -127,6 +130,7 @@ private <T> FailsafeExecutor<T> registerListeners(RetryPolicy<T> retryPolicy, Ci
     circuitBreaker.onFailure(e -> cbFailure.record());
 
     if (fallback != null) {
+      fallback.onFailedAttempt(e -> fbFailedAttempt.record());
       fallback.onSuccess(e -> fbSuccess.record());
       fallback.onFailure(e -> fbFailure.record());
     }
@@ -173,6 +177,7 @@ private void assertForSuccess(boolean sync) throws Throwable {
     cbSuccess.assertEquals(1);
     cbFailure.assertEquals(4);
 
+    fbFailedAttempt.assertEquals(0);
     fbSuccess.assertEquals(1);
     fbFailure.assertEquals(0);
 
@@ -351,6 +356,7 @@ private void assertForFailingRetryPolicy(boolean sync) throws Throwable {
     cbSuccess.assertEquals(3);
     cbFailure.assertEquals(0);
 
+    fbFailedAttempt.assertEquals(0);
     fbSuccess.assertEquals(1);
     fbFailure.assertEquals(0);
 
@@ -392,6 +398,7 @@ private void assertForFailingCircuitBreaker(boolean sync) throws Throwable {
     cbSuccess.assertEquals(0);
     cbFailure.assertEquals(1);
 
+    fbFailedAttempt.assertEquals(0);
     fbSuccess.assertEquals(1);
     fbFailure.assertEquals(0);
 
@@ -433,6 +440,7 @@ private void assertForFailingFallback(boolean sync) throws Throwable {
     cbSuccess.assertEquals(1);
     cbFailure.assertEquals(0);
 
+    fbFailedAttempt.assertEquals(1);
     fbSuccess.assertEquals(0);
     fbFailure.assertEquals(1);
 

src/test/java/net/jodah/failsafe/issues/Issue284Test.java

@@ -7,35 +7,44 @@
 import org.testng.annotations.Test;
 
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.testng.Assert.*;
 
 @Test
 public class Issue284Test {
+  AtomicInteger failedAttempt;
   AtomicBoolean success;
   AtomicBoolean failure;
   AtomicBoolean executed;
   Fallback<String> fallback;
   RetryPolicy<String> retryPolicy = new RetryPolicy<String>().handleResult(null)
+    .onFailedAttempt(e -> failedAttempt.incrementAndGet())
     .onSuccess(e -> success.set(true))
     .onFailure(e -> failure.set(true));
 
   @BeforeMethod
   protected void beforeMethod() {
+    failedAttempt = new AtomicInteger();
     success = new AtomicBoolean();
     failure = new AtomicBoolean();
     executed = new AtomicBoolean();
   }
 
   private Fallback<String> fallbackFor(String result) {
-    return Fallback.of(result).handleResult(null).onSuccess(e -> success.set(true)).onFailure(e -> failure.set(true));
+    return Fallback.of(result)
+      .handleResult(null)
+      .onFailedAttempt(e -> failedAttempt.incrementAndGet())
+      .onSuccess(e -> success.set(true))
+      .onFailure(e -> failure.set(true));
   }
 
   public void testFallbackSuccess() {
     fallback = fallbackFor("hello");
     String result = Failsafe.with(fallback).get(() -> null);
 
     assertEquals(result, "hello");
+    assertEquals(failedAttempt.get(), 0);
     assertTrue(success.get(), "Fallback should have been successful");
   }
 
@@ -44,20 +53,23 @@ public void testFallbackFailure() {
     String result = Failsafe.with(fallback).get(() -> null);
 
     assertNull(result);
+    assertEquals(failedAttempt.get(), 1);
     assertTrue(failure.get(), "Fallback should have failed");
   }
 
   public void testRetryPolicySuccess() {
     String result = Failsafe.with(retryPolicy).get(() -> !executed.getAndSet(true) ? null : "hello");
 
     assertEquals(result, "hello");
+    assertEquals(failedAttempt.get(), 1);
     assertTrue(success.get(), "RetryPolicy should have been successful");
   }
 
   public void testRetryPolicyFailure() {
     String result = Failsafe.with(retryPolicy).get(() -> null);
 
     assertNull(result);
+    assertEquals(failedAttempt.get(), 3);
     assertTrue(failure.get(), "RetryPolicy should have failed");
   }
 }