Added API in Operation queue to add custom executor

Author: Dwivedi

src/com/kryonite/modules/operations/OperationQueue.java

@@ -14,6 +14,7 @@ public class OperationQueue {
     private long maxExecutionTime = -1;
     private int maxConcurrentOperations = 0;
     private ExecutorService executor = null;
+    private boolean terminateExecutorAutomatically = true;
     private boolean autoFinishOperationsOnCompletion = false;
     private OperationList operationList = new OperationList();
 
@@ -34,6 +35,15 @@ public OperationQueue(int maxConcurrentOperations) {
         setMaxConcurrentOperationsCount(maxConcurrentOperations);
     }
 
+    /**
+     * Initializes operation queue with a custom executor.
+     * @param customExecutor
+     */
+    public OperationQueue(ExecutorService customExecutor) {
+        this.executor = customExecutor;
+        terminateExecutorAutomatically = false;
+    }
+
     /**
      * Adds the specified operation to the queue and begins it's execution provided all its dependencies are satisfied.
      * @param operation
@@ -121,7 +131,7 @@ void executeOperation(Operation operation) {
     synchronized void notifyOperationComplete(Operation operation) {
         operationList.removeOperation(operation);
 
-        if (operationList.isEmpty()) {
+        if (operationList.isEmpty() && terminateExecutorAutomatically) {
             executor.shutdownNow();
         }
     }
@@ -136,4 +146,4 @@ private void trackOperation(Operation operation) {
     private synchronized void initExecutor() {
         this.executor = Executors.newFixedThreadPool(maxConcurrentOperations);
     }
-}
+}