Add shadowing samples

Author: yux0

build.gradle

@@ -35,7 +35,7 @@ repositories {
 dependencies {
     errorproneJavac("com.google.errorprone:javac:9+181-r4173-1")
     errorprone("com.google.errorprone:error_prone_core:2.3.1")
-    compile group: 'com.uber.cadence', name: 'cadence-client', version: '3.0.0'
+    compile group: 'com.uber.cadence', name: 'cadence-client', version: '3.1.0'
     compile group: 'commons-configuration', name: 'commons-configuration', version: '1.9'
     compile group: 'ch.qos.logback', name: 'logback-classic', version: '1.2.3'
     compile group: 'com.uber.m3', name: 'tally-core', version: '0.10.0'

src/main/java/com/uber/cadence/samples/hello/HelloAsync.java

@@ -66,6 +66,7 @@ public static class GreetingWorkflowImpl implements GreetingWorkflow {
 
     @Override
     public String getGreeting(String name) {
+
       // Async.invoke takes method reference and activity parameters and returns Promise.
       Promise<String> hello = Async.function(activities::composeGreeting, "Hello", name);
       Promise<String> bye = Async.function(activities::composeGreeting, "Bye", name);

src/main/java/com/uber/cadence/samples/shadowing/README.md

@@ -0,0 +1,37 @@
+##Shadowing example:
+
+Shadowing worker uses for detecting workflow non-deterministic error 
+prior to the workflow code deployment to prod.
+
+More detail can be found: [design doc](https://github.com/uber/cadence/blob/master/docs/design/workflow-shadowing/2547-workflow-shadowing.md)
+
+1. To run this example, start a 0.21+ cadence server.
+
+2. Run a few HelloActivity workflow to generate workflow records.
+```
+./gradlew -q execute -PmainClass=com.uber.cadence.samples.hello.HelloActivity
+```
+
+3. Run the traffic shadowing
+```
+./gradlew -q execute -PmainClass=com.uber.cadence.samples.shadowing.ShadowTraffic
+```
+
+4. No non-deterministic error is expected in the stdout.
+
+5. Add a non backward compatible change to HelloActivity.
+```
+for example: add a timer between workflow start and activity schedule
+
+Workflow.sleep(1000);
+
+```
+
+6. Run the traffic shadowing
+```
+./gradlew -q execute -PmainClass=com.uber.cadence.samples.shadowing.ShadowTraffic
+```
+
+7. Non-deterministic error is expected in the stdout.
+
+

src/main/java/com/uber/cadence/samples/shadowing/ShadowTraffic.java

@@ -0,0 +1,59 @@
+package com.uber.cadence.samples.shadowing;
+
+import com.google.common.collect.Lists;
+import com.uber.cadence.client.WorkflowClient;
+import com.uber.cadence.client.WorkflowClientOptions;
+import com.uber.cadence.samples.hello.HelloActivity;
+import com.uber.cadence.serviceclient.ClientOptions;
+import com.uber.cadence.serviceclient.WorkflowServiceTChannel;
+import com.uber.cadence.shadower.ExitCondition;
+import com.uber.cadence.shadower.Mode;
+import com.uber.cadence.worker.ShadowingOptions;
+import com.uber.cadence.worker.ShadowingWorker;
+import com.uber.cadence.worker.WorkerOptions;
+import com.uber.cadence.worker.WorkflowStatus;
+
+import java.util.concurrent.CountDownLatch;
+
+import static com.uber.cadence.samples.common.SampleConstants.DOMAIN;
+
+public class ShadowTraffic {
+    public static void main(String[] args) throws InterruptedException {
+        // Get a new client
+        // NOTE: to set a different options, you can do like this:
+        // ClientOptions.newBuilder().setRpcTimeout(5 * 1000).build();
+        WorkflowClient workflowClient =
+                WorkflowClient.newInstance(
+                        new WorkflowServiceTChannel(ClientOptions.defaultInstance()),
+                        WorkflowClientOptions.newBuilder().setDomain(DOMAIN).build());
+        ShadowingOptions options = ShadowingOptions
+                .newBuilder()
+                .setDomain(DOMAIN)
+                .setShadowMode(Mode.Normal)
+                .setWorkflowTypes(Lists.newArrayList("GreetingWorkflow::getGreeting"))
+                .setWorkflowStatuses(Lists.newArrayList(WorkflowStatus.OPEN, WorkflowStatus.CLOSED))
+                .setExitCondition(new ExitCondition().setExpirationIntervalInSeconds(60))
+                .build();
+
+        ShadowingWorker shadowingWorker = new ShadowingWorker(
+                workflowClient,
+                "HelloActivity",
+                WorkerOptions.defaultInstance(),
+                options);
+        shadowingWorker.registerWorkflowImplementationTypes(HelloActivity.GreetingWorkflowImpl.class);
+
+        CountDownLatch latch = new CountDownLatch(1);
+        // Execute a workflow waiting for it to complete.
+        Runnable runnable = () -> {
+            try {
+                shadowingWorker.start();
+            } catch (Exception e) {
+                System.out.println("Failed to start shadowing workflow");
+                System.out.println(e);
+                latch.countDown();
+            }
+        };
+        runnable.run();
+        latch.await();
+    }
+}

src/test/java/com/uber/cadence/samples/hello/HelloWorkflowShadowingTest.java

@@ -0,0 +1,52 @@
+/*
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017-2021 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file 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.uber.cadence.samples.hello;
+
+import com.google.common.collect.Lists;
+import com.uber.cadence.serviceclient.ClientOptions;
+import com.uber.cadence.serviceclient.IWorkflowService;
+import com.uber.cadence.serviceclient.WorkflowServiceTChannel;
+import com.uber.cadence.shadower.ExitCondition;
+import com.uber.cadence.shadower.Mode;
+import com.uber.cadence.testing.WorkflowShadower;
+import com.uber.cadence.worker.ShadowingOptions;
+import com.uber.cadence.worker.WorkflowStatus;
+import org.junit.Test;
+
+import static com.uber.cadence.samples.common.SampleConstants.DOMAIN;
+import static com.uber.cadence.samples.hello.HelloActivity.TASK_LIST;
+
+public class HelloWorkflowShadowingTest {
+  @Test
+  public void testShadowing() throws Throwable {
+    IWorkflowService service = new WorkflowServiceTChannel(ClientOptions.defaultInstance());
+
+    ShadowingOptions options = ShadowingOptions
+            .newBuilder()
+            .setDomain(DOMAIN)
+            .setShadowMode(Mode.Normal)
+            .setWorkflowTypes(Lists.newArrayList("GreetingWorkflow::getGreeting"))
+            .setWorkflowStatuses(Lists.newArrayList(WorkflowStatus.OPEN, WorkflowStatus.CLOSED))
+            .setExitCondition(new ExitCondition().setExpirationIntervalInSeconds(60))
+            .build();
+    WorkflowShadower shadower = new WorkflowShadower(service, options, TASK_LIST);
+    shadower.registerWorkflowImplementationTypes(HelloActivity.GreetingWorkflowImpl.class);
+
+    shadower.run();
+  }
+}