Add worker thread

Author: siri-varma

client/src/main/java/com/microsoft/durabletask/DurableTaskGrpcWorker.java

@@ -65,7 +65,7 @@ public final class DurableTaskGrpcWorker implements AutoCloseable {
         this.sidecarClient = TaskHubSidecarServiceGrpc.newBlockingStub(sidecarGrpcChannel);
         this.dataConverter = builder.dataConverter != null ? builder.dataConverter : new JacksonDataConverter();
         this.maximumTimerInterval = builder.maximumTimerInterval != null ? builder.maximumTimerInterval : DEFAULT_MAXIMUM_TIMER_INTERVAL;
-        this.workerPool = Executors.newCachedThreadPool();
+        this.workerPool = builder.executorService;
     }
 
     /**
@@ -86,20 +86,8 @@ public void start() {
      * configured.
      */
     public void close() {
-        this.closeSideCarChannel();
         this.shutDownWorkerPool();
-    }
-
-    private void closeSideCarChannel() {
-        if (this.managedSidecarChannel != null) {
-            try {
-                this.managedSidecarChannel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
-            } catch (InterruptedException e) {
-                // Best effort. Also note that AutoClose documentation recommends NOT having
-                // close() methods throw InterruptedException:
-                // https://docs.oracle.com/javase/7/docs/api/java/lang/AutoCloseable.html
-            }
-        }
+        this.closeSideCarChannel();
     }
 
     /**
@@ -213,6 +201,18 @@ public void stop() {
         this.close();
     }
 
+    private void closeSideCarChannel() {
+        if (this.managedSidecarChannel != null) {
+            try {
+                this.managedSidecarChannel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+            } catch (InterruptedException e) {
+                // Best effort. Also note that AutoClose documentation recommends NOT having
+                // close() methods throw InterruptedException:
+                // https://docs.oracle.com/javase/7/docs/api/java/lang/AutoCloseable.html
+            }
+        }
+    }
+
     private void shutDownWorkerPool() {
         this.workerPool.shutdown();
         try {

client/src/main/java/com/microsoft/durabletask/DurableTaskGrpcWorkerBuilder.java

@@ -6,6 +6,9 @@
 
 import java.time.Duration;
 import java.util.HashMap;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 /**
  * Builder object for constructing customized {@link DurableTaskGrpcWorker} instances.
@@ -17,6 +20,7 @@ public final class DurableTaskGrpcWorkerBuilder {
     Channel channel;
     DataConverter dataConverter;
     Duration maximumTimerInterval;
+    ExecutorService executorService;
 
     /**
      * Adds an orchestration factory to be used by the constructed {@link DurableTaskGrpcWorker}.
@@ -113,6 +117,17 @@ public DurableTaskGrpcWorkerBuilder maximumTimerInterval(Duration maximumTimerIn
         return this;
     }
 
+    /**
+     * Sets the executor service that will be used to execute threads.
+     *
+     * @param executorService {@link ExecutorService}.
+     * @return this builder object.
+     */
+    public DurableTaskGrpcWorkerBuilder withExecutorService(ExecutorService executorService) {
+        this.executorService = executorService;
+        return this;
+    }
+
     /**
      * Initializes a new {@link DurableTaskGrpcWorker} object with the settings specified in the current builder object.
      * @return a new {@link DurableTaskGrpcWorker} object