Invoke onSuccess and onFailure handlers properly for async methods

tritium-lib/src/main/java/com/palantir/tritium/proxy/InvocationEventProxy.java

@@ -19,6 +19,10 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.reflect.AbstractInvocationHandler;
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.MoreExecutors;
 import com.google.errorprone.annotations.CompileTimeConstant;
 import com.palantir.logsafe.SafeArg;
 import com.palantir.logsafe.UnsafeArg;
@@ -32,6 +36,7 @@
 import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.CompletableFuture;
 import javax.annotation.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -116,14 +121,52 @@ public final Object instrumentInvocation(Object instance, Method method, Object[
         InvocationContext context = handlePreInvocation(instance, method, args);
         try {
             Object result = execute(method, args);
-            return handleOnSuccess(context, result);
+            return handleResult(context, result);
         } catch (InvocationTargetException e) {
             throw handleOnFailure(context, e.getCause());
         } catch (Throwable t) {
             throw handleOnFailure(context, t);
         }
     }
 
+    private Object handleResult(InvocationContext context, Object result) {
+        if (result instanceof ListenableFuture) {
+            return handleFuture(context, (ListenableFuture) result);
+        } else if (result instanceof CompletableFuture) {
+            return handleFuture(context, (CompletableFuture) result);
+        } else {
+            return handleOnSuccess(context, result);
+        }
+    }
+
+    private CompletableFuture<?> handleFuture(InvocationContext context, CompletableFuture<?> future) {
+        future.handleAsync((result, throwable) -> {
+            if (throwable == null) {
+                return handleOnSuccess(context, result);
+            } else {
+                return handleOnFailure(context, throwable);
+            }
+        }, MoreExecutors.directExecutor());
+
+        return future;
+    }
+
+    private ListenableFuture<?> handleFuture(InvocationContext context, ListenableFuture<?> future) {
+        Futures.addCallback(future, new FutureCallback<Object>() {
+            @Override
+            public void onSuccess(Object result) {
+                handleOnSuccess(context, result);
+            }
+
+            @Override
+            public void onFailure(Throwable t) {
+                handleOnFailure(context, t);
+            }
+        }, MoreExecutors.directExecutor());
+
+        return future;
+    }
+
     @Nullable
     final InvocationContext handlePreInvocation(Object instance, Method method, Object[] args) {
         try {

tritium-lib/src/test/java/com/palantir/tritium/proxy/AsyncInvocationEventProxyTest.java

@@ -0,0 +1,136 @@
+/*
+ * (c) Copyright 2019 Palantir Technologies Inc. All rights reserved.
+ *
+ * Licensed 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 com.palantir.tritium.proxy;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.SettableFuture;
+import com.palantir.tritium.event.DefaultInvocationContext;
+import com.palantir.tritium.event.InvocationContext;
+import com.palantir.tritium.event.InvocationEventHandler;
+import java.lang.reflect.Method;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public final class AsyncInvocationEventProxyTest {
+    private static final String result = "Result";
+
+    @Mock private AsyncIface delegate;
+    @Mock private SimpleInvocationEventHandler handler;
+    private AsyncIface proxy;
+
+    @Before
+    public void before() {
+        proxy = Instrumentation.builder(AsyncIface.class, delegate)
+                .withHandler(handler)
+                .build();
+        when(handler.isEnabled()).thenCallRealMethod();
+        when(handler.preInvocation(any(), any(), any())).thenCallRealMethod();
+    }
+
+    @Test
+    public void testCfSuccess() throws ExecutionException, InterruptedException {
+        CompletableFuture<String> future = new CompletableFuture<>();
+        when(delegate.cf()).thenReturn(future);
+
+        CompletableFuture<String> ret = proxy.cf();
+        assertThat(ret.isDone()).isFalse();
+        verify(handler, never()).onSuccess(any(), any());
+
+        future.complete(result);
+        assertThat(ret.get()).isEqualTo(result);
+        verify(handler).onSuccess(any(), eq(result));
+    }
+
+    @Test
+    public void testCfThrows() {
+        RuntimeException exception = new RuntimeException();
+        CompletableFuture<String> future = new CompletableFuture<>();
+        when(delegate.cf()).thenReturn(future);
+
+        CompletableFuture<String> ret = proxy.cf();
+        assertThat(ret.isDone()).isFalse();
+        verify(handler, never()).onSuccess(any(), any());
+
+        future.completeExceptionally(exception);
+        assertThat(ret.isCompletedExceptionally()).isTrue();
+        verify(handler).onFailure(any(), eq(exception));
+    }
+
+    @Test
+    public void testLfSuccess() {
+        SettableFuture<String> future = SettableFuture.create();
+        when(delegate.lf()).thenReturn(future);
+
+        ListenableFuture<String> ret = proxy.lf();
+        assertThat(ret.isDone()).isFalse();
+        verify(handler, never()).onSuccess(any(), any());
+
+        future.set(result);
+        assertThat(ret.isDone()).isTrue();
+        verify(handler).onSuccess(any(), eq(result));
+    }
+
+    @Test
+    public void testLfThrows() {
+        RuntimeException exception = new RuntimeException();
+        SettableFuture<String> future = SettableFuture.create();
+        when(delegate.lf()).thenReturn(future);
+
+        ListenableFuture<String> ret = proxy.lf();
+        assertThat(ret.isDone()).isFalse();
+        verify(handler, never()).onFailure(any(), any());
+
+        future.setException(exception);
+        assertThat(ret.isDone()).isTrue();
+        verify(handler).onFailure(any(), eq(exception));
+    }
+
+    interface AsyncIface {
+        CompletableFuture<String> cf();
+
+        ListenableFuture<String> lf();
+    }
+
+    interface SimpleInvocationEventHandler extends InvocationEventHandler<InvocationContext> {
+        @Override
+        default boolean isEnabled() {
+            return true;
+        }
+
+        @Override
+        default InvocationContext preInvocation(Object instance, Method method, Object[] args) {
+            return DefaultInvocationContext.of(instance, method, args);
+        }
+    }
+}

tritium-lib/src/test/java/com/palantir/tritium/proxy/InvocationEventProxyTest.java

@@ -138,6 +138,11 @@ public void onFailure(@Nullable InvocationContext context, @Nonnull Throwable ca
         assertThat(throwable).isSameAs(expected);
     }
 
+    @Test
+    public void testInstrumentCompletableFuture() {
+
+    }
+
     @Test
     public void testToInvocationDebugString() throws Exception {
         Throwable cause = new RuntimeException("cause");