GERONIMO-6591 - Adding fallback support.

safeguard-impl/src/main/java/org/apache/safeguard/impl/FailsafeExecutionManager.java

@@ -44,20 +44,20 @@ public FailsafeExecutionManager() {
 
     public Object execute(InvocationContext invocationContext) {
         Method method = invocationContext.getMethod();
-        return executionPlanFactory.locateExecutionPlan(method).execute(invocationContext::proceed);
+        return executionPlanFactory.locateExecutionPlan(method).execute(invocationContext::proceed, invocationContext);
     }
 
     @Override
     public <T> T execute(String name, Callable<T> callable) {
-        return executionPlanFactory.locateExecutionPlan(name, null, false).execute(callable);
+        return executionPlanFactory.locateExecutionPlan(name, null, false).execute(callable, null);
     }
 
     public <T> T executeAsync(String name, Callable<T> callable) {
-        return executionPlanFactory.locateExecutionPlan(name, null, true).execute(callable);
+        return executionPlanFactory.locateExecutionPlan(name, null, true).execute(callable, null);
     }
 
     public <T> T executeAsync(String name, Callable<T> callable, Duration timeout) {
-        return executionPlanFactory.locateExecutionPlan(name, timeout, true).execute(callable);
+        return executionPlanFactory.locateExecutionPlan(name, timeout, true).execute(callable, null);
     }
 
     public ExecutionPlanFactory getExecutionPlanFactory() {

safeguard-impl/src/main/java/org/apache/safeguard/impl/executionPlans/AsyncFailsafeExecutionPlan.java

@@ -22,31 +22,32 @@
 import net.jodah.failsafe.AsyncFailsafe;
 import net.jodah.failsafe.CircuitBreakerOpenException;
 import org.apache.safeguard.impl.circuitbreaker.FailsafeCircuitBreaker;
+import org.apache.safeguard.impl.fallback.FallbackRunner;
 import org.apache.safeguard.impl.retry.FailsafeRetryDefinition;
 
+import javax.interceptor.InvocationContext;
 import java.time.Duration;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.TimeoutException;
 
 public class AsyncFailsafeExecutionPlan extends SyncFailsafeExecutionPlan {
     private final ScheduledExecutorService executorService;
     private final Duration timeout;
 
     public AsyncFailsafeExecutionPlan(FailsafeRetryDefinition retryDefinition,
                                       FailsafeCircuitBreaker failsafeCircuitBreaker,
+                                      FallbackRunner fallback,
                                       ScheduledExecutorService executorService,
                                       Duration timeout) {
-        super(retryDefinition, failsafeCircuitBreaker);
+        super(retryDefinition, failsafeCircuitBreaker, fallback);
         this.executorService = executorService;
         this.timeout = timeout;
     }
 
     @Override
-    public <T> T execute(Callable<T> callable) {
-        AsyncFailsafe<?> asyncFailsafe = getSyncFailsafe().with(executorService);
+    public <T> T execute(Callable<T> callable, InvocationContext invocationContext) {
+        AsyncFailsafe<?> asyncFailsafe = getSyncFailsafe(invocationContext).with(executorService);
         try {
             if (this.timeout == null) {
                 return asyncFailsafe.get(callable).get();

safeguard-impl/src/main/java/org/apache/safeguard/impl/executionPlans/AsyncOnlyExecutionPlan.java

@@ -21,6 +21,7 @@
 
 import org.apache.safeguard.exception.AsyncException;
 
+import javax.interceptor.InvocationContext;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
@@ -34,7 +35,7 @@ class AsyncOnlyExecutionPlan implements ExecutionPlan {
     }
 
     @Override
-    public <T> T execute(Callable<T> callable) {
+    public <T> T execute(Callable<T> callable, InvocationContext invocationContext) {
         Future<T> submitted = executorService.submit(callable);
         try {
             return submitted.get();

safeguard-impl/src/main/java/org/apache/safeguard/impl/executionPlans/AsyncTimeoutExecutionPlan.java

@@ -19,6 +19,7 @@
 
 package org.apache.safeguard.impl.executionPlans;
 
+import javax.interceptor.InvocationContext;
 import java.time.Duration;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
@@ -37,7 +38,7 @@ class AsyncTimeoutExecutionPlan implements ExecutionPlan {
     }
 
     @Override
-    public <T> T execute(Callable<T> callable) {
+    public <T> T execute(Callable<T> callable, InvocationContext invocationContext) {
         Future<T> future = executorService.submit(callable);
         try {
             return future.get(timeout.toMillis(), TimeUnit.MILLISECONDS);

safeguard-impl/src/main/java/org/apache/safeguard/impl/executionPlans/ExecutionPlan.java

@@ -19,8 +19,9 @@
 
 package org.apache.safeguard.impl.executionPlans;
 
+import javax.interceptor.InvocationContext;
 import java.util.concurrent.Callable;
 
 public interface ExecutionPlan {
-    <T> T execute(Callable<T> callable);
+    <T> T execute(Callable<T> function, InvocationContext invocationContext);
 }

safeguard-impl/src/main/java/org/apache/safeguard/impl/executionPlans/ExecutionPlanFactory.java

@@ -22,20 +22,23 @@
 import org.apache.safeguard.impl.circuitbreaker.FailsafeCircuitBreaker;
 import org.apache.safeguard.impl.circuitbreaker.FailsafeCircuitBreakerBuilder;
 import org.apache.safeguard.impl.circuitbreaker.FailsafeCircuitBreakerManager;
+import org.apache.safeguard.impl.fallback.FallbackRunner;
 import org.apache.safeguard.impl.retry.FailsafeRetryBuilder;
 import org.apache.safeguard.impl.retry.FailsafeRetryDefinition;
 import org.apache.safeguard.impl.retry.FailsafeRetryManager;
 import org.apache.safeguard.impl.util.AnnotationUtil;
 import org.apache.safeguard.impl.util.NamingUtil;
 import org.eclipse.microprofile.faulttolerance.Asynchronous;
 import org.eclipse.microprofile.faulttolerance.CircuitBreaker;
+import org.eclipse.microprofile.faulttolerance.Fallback;
 import org.eclipse.microprofile.faulttolerance.Retry;
 import org.eclipse.microprofile.faulttolerance.Timeout;
 
 import java.lang.reflect.Method;
 import java.time.Duration;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.Callable;
 import java.util.concurrent.Executors;
 
 import static org.apache.safeguard.impl.executionPlans.MicroprofileAnnotationMapper.mapCircuitBreaker;
@@ -58,7 +61,7 @@ public ExecutionPlan locateExecutionPlan(String name, Duration timeout, boolean
             if (circuitBreaker == null && retryDefinition == null) {
                 return null;
             } else {
-                return new SyncFailsafeExecutionPlan(retryDefinition, circuitBreaker);
+                return new SyncFailsafeExecutionPlan(retryDefinition, circuitBreaker, null);
             }
         });
     }
@@ -76,6 +79,7 @@ public ExecutionPlan locateExecutionPlan(Method method) {
             }
             boolean isAsync = isAsync(method);
             Duration timeout = readTimeout(method);
+            FallbackRunner fallbackRunner = this.createFallback(method);
             if(circuitBreaker == null && retryDefinition == null && isAsync) {
                 if(timeout == null) {
                     return new AsyncOnlyExecutionPlan(null);
@@ -90,9 +94,9 @@ else if(circuitBreaker == null && retryDefinition == null && timeout != null) {
             }
             else {
                 if (isAsync || timeout != null) {
-                    return new AsyncFailsafeExecutionPlan(retryDefinition, circuitBreaker, Executors.newScheduledThreadPool(5), timeout);
+                    return new AsyncFailsafeExecutionPlan(retryDefinition, circuitBreaker, fallbackRunner, Executors.newScheduledThreadPool(5), timeout);
                 } else {
-                    return new SyncFailsafeExecutionPlan(retryDefinition, circuitBreaker);
+                    return new SyncFailsafeExecutionPlan(retryDefinition, circuitBreaker, fallbackRunner);
                 }
             }
         });
@@ -116,6 +120,15 @@ private FailsafeCircuitBreaker createCBDefinition(String name, Method method) {
         return new FailsafeCircuitBreaker(mapCircuitBreaker(circuitBreaker, circuitBreakerBuilder));
     }
 
+    private FallbackRunner createFallback(Method method) {
+        Fallback fallback = AnnotationUtil.getAnnotation(method, Fallback.class);
+        if(fallback == null) {
+            return null;
+        }
+        String methodName = "".equals(fallback.fallbackMethod()) ? null : fallback.fallbackMethod();
+        return new FallbackRunner(fallback.value(), methodName);
+    }
+
     private boolean isAsync(Method method) {
         return AnnotationUtil.getAnnotation(method, Asynchronous.class) != null;
     }

safeguard-impl/src/main/java/org/apache/safeguard/impl/executionPlans/SyncFailsafeExecutionPlan.java

@@ -23,17 +23,22 @@
 import net.jodah.failsafe.Failsafe;
 import net.jodah.failsafe.SyncFailsafe;
 import org.apache.safeguard.impl.circuitbreaker.FailsafeCircuitBreaker;
+import org.apache.safeguard.impl.fallback.FallbackRunner;
 import org.apache.safeguard.impl.retry.FailsafeRetryDefinition;
 
+import javax.interceptor.InvocationContext;
 import java.util.concurrent.Callable;
+import java.util.function.Function;
 
 public class SyncFailsafeExecutionPlan implements ExecutionPlan {
     private final FailsafeRetryDefinition retryDefinition;
     private final FailsafeCircuitBreaker failsafeCircuitBreaker;
+    private final FallbackRunner fallback;
 
-    SyncFailsafeExecutionPlan(FailsafeRetryDefinition retryDefinition, FailsafeCircuitBreaker failsafeCircuitBreaker) {
+    SyncFailsafeExecutionPlan(FailsafeRetryDefinition retryDefinition, FailsafeCircuitBreaker failsafeCircuitBreaker, FallbackRunner fallback) {
         this.retryDefinition = retryDefinition;
         this.failsafeCircuitBreaker = failsafeCircuitBreaker;
+        this.fallback = fallback;
         validateConfig();
     }
 
@@ -44,17 +49,18 @@ private void validateConfig() {
     }
 
     @Override
-    public <T> T execute(Callable<T> callable) {
-        SyncFailsafe<?> syncFailsafe = getSyncFailsafe();
+    public <T> T execute(Callable<T> callable, InvocationContext invocationContext) {
+        SyncFailsafe<?> syncFailsafe = getSyncFailsafe(invocationContext);
         try {
             return syncFailsafe.get(callable);
         } catch (CircuitBreakerOpenException e) {
             throw new org.eclipse.microprofile.faulttolerance.exceptions.CircuitBreakerOpenException(e);
         }
     }
 
-    SyncFailsafe<?> getSyncFailsafe() {
+    SyncFailsafe<?> getSyncFailsafe(InvocationContext invocationContext) {
         SyncFailsafe<?> syncFailsafe;
+        Callable callable = () -> fallback.executeFallback(invocationContext);
         if(retryDefinition == null) {
             syncFailsafe = Failsafe.with(failsafeCircuitBreaker.getDefinition().getCircuitBreaker());
         }
@@ -67,6 +73,9 @@ SyncFailsafe<?> getSyncFailsafe() {
                         .with(failsafeCircuitBreaker.getDefinition().getCircuitBreaker());
             }
         }
+        if(this.fallback != null) {
+            syncFailsafe = syncFailsafe.withFallback(callable);
+        }
         return syncFailsafe;
     }
 }

safeguard-impl/src/main/java/org/apache/safeguard/impl/fallback/FallbackRunner.java

@@ -0,0 +1,102 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+
+package org.apache.safeguard.impl.fallback;
+
+import org.eclipse.microprofile.faulttolerance.ExecutionContext;
+import org.eclipse.microprofile.faulttolerance.FallbackHandler;
+
+import javax.enterprise.inject.spi.CDI;
+import javax.interceptor.InvocationContext;
+import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+
+public class FallbackRunner {
+    private final Class<? extends FallbackHandler<?>> handlerClass;
+    private final String method;
+
+    public FallbackRunner(Class<? extends FallbackHandler<?>> handlerClass, String method) {
+        this.handlerClass = handlerClass;
+        this.method = method;
+    }
+
+    public Object executeFallback(InvocationContext invocationContext) {
+        if(method != null) {
+            try {
+                Method method = getMethod(invocationContext.getTarget().getClass());
+                Parameter[] parameters = method.getParameters();
+                if(parameters.length == 0) {
+                    return method.invoke(invocationContext.getTarget());
+                }
+                else {
+                    return method.invoke(invocationContext.getTarget(), invocationContext.getParameters());
+                }
+            } catch (Exception e) {
+                throw new IllegalArgumentException(e);
+            }
+        }
+        else {
+            SafeguardExecutionContext executionContext = new SafeguardExecutionContext(invocationContext.getMethod(),
+                    invocationContext.getParameters());
+            CDI<Object> cdi = CDI.current();
+            FallbackHandler fallbackHandler = null;
+            try {
+                fallbackHandler = cdi.select(handlerClass).get();
+            }
+            catch (Exception e) {
+                try {
+                    fallbackHandler = handlerClass.newInstance();
+                } catch (InstantiationException | IllegalAccessException e1) {
+                    throw new IllegalArgumentException(e);
+                }
+            }
+            return fallbackHandler.handle(executionContext);
+        }
+    }
+
+    private Method getMethod(Class<?> aClass) {
+        for(Method method : aClass.getMethods()) {
+            if(method.getName().equals(this.method)) {
+                return method;
+            }
+        }
+        return null;
+    }
+
+    private static class SafeguardExecutionContext implements ExecutionContext {
+
+        private final Method method;
+        private final Object[] parameters;
+
+        private SafeguardExecutionContext(Method method, Object[] parameters) {
+            this.method = method;
+            this.parameters = parameters;
+        }
+
+        @Override
+        public Method getMethod() {
+            return method;
+        }
+
+        @Override
+        public Object[] getParameters() {
+            return parameters;
+        }
+    }
+}

safeguard-impl/src/test/java/org/apache/safeguard/impl/executionPlans/AsyncOnlyExecutionPlanTest.java

@@ -32,7 +32,7 @@ public class AsyncOnlyExecutionPlanTest {
     public void shouldExecuteAsncWithoutTimeout() {
         AsyncOnlyExecutionPlan asyncOnlyExecutionPlan = new AsyncOnlyExecutionPlan(Executors.newFixedThreadPool(2));
         MyCallable callable = new MyCallable();
-        asyncOnlyExecutionPlan.execute(callable);
+        asyncOnlyExecutionPlan.execute(callable, null);
         assertThat(callable.calledThread).isNotEqualTo(Thread.currentThread().getName());
     }
 

safeguard-impl/src/test/java/org/apache/safeguard/impl/executionPlans/AsyncTimeoutExecutionPlanTest.java

@@ -35,7 +35,7 @@ public void shouldExecuteSimpleCallable() {
         AsyncTimeoutExecutionPlan asyncTimeoutExecutionPlan = new AsyncTimeoutExecutionPlan(Duration.ofMillis(1000), Executors.newSingleThreadExecutor());
         DelayedCaller callable = new DelayedCaller(200);
 
-        asyncTimeoutExecutionPlan.execute(callable);
+        asyncTimeoutExecutionPlan.execute(callable, null);
 
         String myThreadName = Thread.currentThread().getName();
         assertThat(callable.executedThread).isNotEqualTo(myThreadName);
@@ -46,7 +46,7 @@ public void shouldThrowTimeoutWhenDelayHit() {
         AsyncTimeoutExecutionPlan asyncTimeoutExecutionPlan = new AsyncTimeoutExecutionPlan(Duration.ofMillis(100), Executors.newSingleThreadExecutor());
         DelayedCaller callable = new DelayedCaller(200);
 
-        assertThatThrownBy(() -> asyncTimeoutExecutionPlan.execute(callable)).isInstanceOf(TimeoutException.class);
+        assertThatThrownBy(() -> asyncTimeoutExecutionPlan.execute(callable, null)).isInstanceOf(TimeoutException.class);
     }
 
     private static class DelayedCaller implements Callable<Object> {

safeguard-impl/src/test/java/org/apache/safeguard/impl/executionPlans/SyncFailsafeExecutionPlanTest.java

@@ -26,7 +26,7 @@
 public class SyncFailsafeExecutionPlanTest {
     @Test
     public void shouldThrowExceptionWithInvalidConfig() {
-        assertThatThrownBy(() -> new SyncFailsafeExecutionPlan(null, null))
+        assertThatThrownBy(() -> new SyncFailsafeExecutionPlan(null, null, null))
                 .isInstanceOf(IllegalStateException.class)
                 .hasMessage("For non-async invocations, must have at least one of RetryDefintion or CircuitBreaker defined");
     }