chore: Add idempotency example

Signed-off-by: Javier Aliaga <[email protected]>

Author: javier-aliaga

examples/src/main/java/io/dapr/examples/workflows/README.md

@@ -53,6 +53,8 @@ Those examples contain the following workflow patterns:
 4. [External Event Pattern](#external-event-pattern)
 5. [Child-workflow Pattern](#child-workflow-pattern)
 6. [Compensation Pattern](#compensation-pattern)
+6. [Suspend/resume Pattern](#suspendresume-pattern)
+7. [Idempotency Pattern](#idempotency-pattern) 
 
 ### Chaining Pattern
 In the chaining pattern, a sequence of activities executes in a specific order.
@@ -707,4 +709,6 @@ The client log:
 ```text
 Started a new external-event model workflow with instance ID: 23410d96-1afe-4698-9fcd-c01c1e0db255
 workflow instance with ID: 23410d96-1afe-4698-9fcd-c01c1e0db255 completed.
-```
+```
+
+### Idempotency Pattern

examples/src/main/java/io/dapr/examples/workflows/idempotency/IdempotencyClient.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2025 The Dapr Authors
+ * 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 io.dapr.examples.workflows.idempotency;
+
+import io.dapr.workflows.client.DaprWorkflowClient;
+import io.dapr.workflows.client.WorkflowInstanceStatus;
+import io.dapr.workflows.client.WorkflowRuntimeStatus;
+
+import java.util.ArrayList;
+import java.util.concurrent.TimeoutException;
+
+public class IdempotencyClient {
+  /**
+   * The main method to start the client.
+   *
+   * @param args Input arguments (unused).
+   * @throws InterruptedException If program has been interrupted.
+   */
+  public static void main(String[] args) {
+    try (DaprWorkflowClient client = new DaprWorkflowClient()) {
+      String instanceId = client.scheduleNewWorkflow(IdempotentWorkflow.class);
+      System.out.printf("Started a new chaining model workflow with instance ID: %s%n", instanceId);
+      WorkflowInstanceStatus workflowInstanceStatus =
+          client.waitForInstanceCompletion(instanceId, null, true);
+
+      if (workflowInstanceStatus == null) {
+        System.out.printf("workflow instance with ID: %s not found%n", instanceId);
+        return;
+      }
+
+      if (workflowInstanceStatus.getRuntimeStatus() != WorkflowRuntimeStatus.COMPLETED) {
+        System.out.printf("workflow instance with ID: %s failed",   instanceId);
+        return;
+      }
+
+      var result = workflowInstanceStatus.readOutputAs(ArrayList.class);
+        System.out.printf("workflow instance with ID: %s completed with result: %s%n", instanceId, result.toString());
+
+    } catch (TimeoutException | InterruptedException e) {
+      throw new RuntimeException(e);
+    }
+  }
+}

examples/src/main/java/io/dapr/examples/workflows/idempotency/IdempotencyWorker.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2025 The Dapr Authors
+ * 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 io.dapr.examples.workflows.idempotency;
+
+import io.dapr.workflows.runtime.WorkflowRuntime;
+import io.dapr.workflows.runtime.WorkflowRuntimeBuilder;
+
+public class IdempotencyWorker {
+  /**
+   * The main method of this app.
+   *
+   * @param args The port the app will listen on.
+   * @throws Exception An Exception.
+   */
+  public static void main(String[] args) throws Exception {
+    // Register the Workflow with the builder.
+    WorkflowRuntimeBuilder builder = new WorkflowRuntimeBuilder().registerWorkflow(IdempotentWorkflow.class);
+    builder.registerActivity(IdempotentActivity.class);
+
+    // Build and then start the workflow runtime pulling and executing tasks
+    WorkflowRuntime runtime = builder.build();
+    System.out.println("Start workflow runtime");
+    runtime.start();
+  }
+}

examples/src/main/java/io/dapr/examples/workflows/idempotency/IdempotentActivity.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2023 The Dapr Authors
+ * 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 io.dapr.examples.workflows.idempotency;
+
+import io.dapr.workflows.WorkflowActivity;
+import io.dapr.workflows.WorkflowActivityContext;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+public class IdempotentActivity implements WorkflowActivity {
+
+  Logger logger = LoggerFactory.getLogger(IdempotentActivity.class);
+
+  @Override
+  public Object run(WorkflowActivityContext ctx) {
+
+    logger.info("[{}] Starting Activity {} ", ctx.getTaskExecutionId(), ctx.getName());
+    var limit = ctx.getInput(Integer.class);
+
+    var counter = IdempotentWorkflow.getKeyStore().getOrDefault(ctx.getTaskExecutionId(), new AtomicInteger(0));
+    if (counter.get() != limit) {
+      logger.info("Task execution key[{}] with limit {}, incrementing counter {}",ctx.getTaskExecutionId(), limit, counter.get());
+      IdempotentWorkflow.getKeyStore().put(ctx.getTaskExecutionId(), new AtomicInteger(counter.incrementAndGet()));
+
+      throw new IllegalStateException("Task execution key not found");
+    }
+    
+    return counter.get();
+  }
+}

examples/src/main/java/io/dapr/examples/workflows/idempotency/IdempotentWorkflow.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2023 The Dapr Authors
+ * 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 io.dapr.examples.workflows.idempotency;
+
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+
+import io.dapr.workflows.Workflow;
+import io.dapr.workflows.WorkflowStub;
+import io.dapr.workflows.WorkflowTaskOptions;
+import io.dapr.workflows.WorkflowTaskRetryPolicy;
+
+
+public class IdempotentWorkflow implements Workflow {
+
+
+  private static Map<String, AtomicInteger> keyStore;
+    
+    
+    public static Map<String, AtomicInteger> getKeyStore() {
+        if (keyStore == null) {
+          synchronized (IdempotentWorkflow.class) {
+              if (keyStore == null) {
+                keyStore = new ConcurrentHashMap<>();
+              }
+          }
+      }
+      return keyStore;
+  }
+
+
+  @Override
+  public WorkflowStub create() {
+    return ctx -> {
+      ctx.getLogger().info("Starting Workflow: " + ctx.getName());
+
+      var result = new ArrayList<Integer>();
+
+      WorkflowTaskOptions options = new WorkflowTaskOptions(WorkflowTaskRetryPolicy.newBuilder()
+      .setMaxNumberOfAttempts(10)
+      .setFirstRetryInterval(Duration.ofSeconds(1))
+      .setMaxRetryInterval(Duration.ofSeconds(10))
+      .setBackoffCoefficient(2.0)  
+      .setRetryTimeout(Duration.ofSeconds(10))
+      .build());
+
+      result.add(ctx.callActivity(IdempotentActivity.class.getName(), 3, options, Integer.class).await());
+      result.add(ctx.callActivity(IdempotentActivity.class.getName(), 2, options, Integer.class).await());
+      result.add(ctx.callActivity(IdempotentActivity.class.getName(), 1, options, Integer.class).await());
+
+      result.forEach(r -> ctx.getLogger().info("Result: " + r));
+
+      ctx.complete(result);
+    };
+  }
+}

sdk-tests/src/test/java/io/dapr/it/testcontainers/KeyStore.java

@@ -12,12 +12,12 @@
 */
 package io.dapr.it.testcontainers;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 public class KeyStore {
 
-    private final Map<String, Boolean> keyStore = new HashMap<>();
+    private final Map<String, Boolean> keyStore = new ConcurrentHashMap<>();
 
     private static KeyStore instance;