expand HelloSignal example to send multiple signals (#1)

* expand HelloSignal example to send multiple signals

Author: halakaraki

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

@@ -27,6 +27,12 @@
 import com.uber.cadence.workflow.Workflow;
 import com.uber.cadence.workflow.WorkflowMethod;
 import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingDeque;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.CompletableFuture;
 
 /**
  * Demonstrates asynchronous signalling of a workflow. Requires a local instance of Cadence server
@@ -39,32 +45,53 @@ public class HelloSignal {
 
   /** Workflow interface must have a method annotated with @WorkflowMethod. */
   public interface GreetingWorkflow {
-    /** @return greeting string */
+    /** @return list of greeting strings that were received through the
+     * waitForNameMethod. This method will block until the number of greetings
+     * specified are received. */
     @WorkflowMethod
-    String getGreeting();
+    List<String> getGreetings();
 
     /** Receives name through an external signal. */
     @SignalMethod
     void waitForName(String name);
+
+    /** Receives name through an external signal. */
+    @SignalMethod
+    void exit();
   }
 
   /** GreetingWorkflow implementation that returns a greeting. */
   public static class GreetingWorkflowImpl implements GreetingWorkflow {
 
-    private final CompletablePromise<String> name = Workflow.newPromise();
+    List<String> messageQueue = new ArrayList<>(10);
+    boolean exit = false;
 
     @Override
-    public String getGreeting() {
-      return "Hello " + name.get() + "!";
+    public List<String> getGreetings() {
+      List<String> receivedMessages = new ArrayList<>(10);
+
+      while (true) {
+        Workflow.await(() -> !messageQueue.isEmpty() || exit);
+        if(messageQueue.isEmpty() && exit){
+          return receivedMessages;
+        }
+        String message = messageQueue.remove(0);
+        receivedMessages.add(message);
+      }
     }
 
     @Override
     public void waitForName(String name) {
-      this.name.complete(name);
+      messageQueue.add("Hello " + name + "!");
+    }
+
+    @Override
+    public void exit() {
+      exit = true;
     }
   }
 
-  public static void main(String[] args) {
+  public static void main(String[] args) throws Exception {
     // Start a worker that hosts the workflow implementation.
     Worker worker = new Worker(DOMAIN, TASK_LIST);
     worker.registerWorkflowImplementationTypes(GreetingWorkflowImpl.class);
@@ -80,17 +107,21 @@ public static void main(String[] args) {
             .build();
     GreetingWorkflow workflow =
         workflowClient.newWorkflowStub(GreetingWorkflow.class, workflowOptions);
+    workflow.wait();
     // Start workflow asynchronously to not use another thread to signal.
-    WorkflowClient.start(workflow::getGreeting);
+    WorkflowClient.start(workflow::getGreetings);
     // After start for getGreeting returns, the workflow is guaranteed to be started.
     // So we can send a signal to it using workflow stub.
+    // This workflow keeps receiving signals until exit is called
     workflow.waitForName("World");
+    workflow.waitForName("Universe");
+    workflow.exit();
     // Calling synchronous getGreeting after workflow has started reconnects to the existing
     // workflow and blocks until a result is available. Note that this behavior assumes that
     // WorkflowOptions are not configured with WorkflowIdReusePolicy.AllowDuplicate. In that case
     // the call would fail with WorkflowExecutionAlreadyStartedException.
-    String greeting = workflow.getGreeting();
-    System.out.println(greeting);
+    List<String> greetings = workflow.getGreetings();
+    System.out.println(greetings);
     System.exit(0);
   }
 }

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

@@ -25,6 +25,9 @@
 import com.uber.cadence.testing.TestWorkflowEnvironment;
 import com.uber.cadence.worker.Worker;
 import java.time.Duration;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Rule;
@@ -68,8 +71,8 @@ public void tearDown() {
     testEnv.close();
   }
 
-  @Test(timeout = 5000)
-  public void testSignal() {
+  @Test//(timeout = 5000)
+  public void testSignal() throws Exception {
     // Get a workflow stub using the same task list the worker uses.
     WorkflowOptions workflowOptions =
         new WorkflowOptions.Builder()
@@ -80,21 +83,25 @@ public void testSignal() {
         workflowClient.newWorkflowStub(GreetingWorkflow.class, workflowOptions);
 
     // Start workflow asynchronously to not use another thread to signal.
-    WorkflowClient.start(workflow::getGreeting);
+    WorkflowClient.start(workflow::getGreetings);
 
     // After start for getGreeting returns, the workflow is guaranteed to be started.
     // So we can send a signal to it using workflow stub immediately.
     // But just to demonstrate the unit testing of a long running workflow adding a long sleep here.
     testEnv.sleep(Duration.ofDays(1));
+    // This workflow keeps receiving signals until exit is called
     workflow.waitForName("World");
+    workflow.waitForName("Universe");
+    workflow.exit();
     // Calling synchronous getGreeting after workflow has started reconnects to the existing
     // workflow and
     // blocks until result is available. Note that this behavior assumes that WorkflowOptions are
     // not configured
     // with WorkflowIdReusePolicy.AllowDuplicate. In that case the call would fail with
     // WorkflowExecutionAlreadyStartedException.
-    String greeting = workflow.getGreeting();
-
-    assertEquals("Hello World!", greeting);
+    List<String> greetings = workflow.getGreetings();
+    assertEquals(2, greetings.size());
+    assertEquals("Hello World!", greetings.get(0));
+    assertEquals("Hello Universe!", greetings.get(1));
   }
 }