Add support for virtual threads with IVMTaskScheduler

Introduce `IVMTaskScheduler` to enable virtual thread scheduling, improving thread management when `swiftmq.jac.active` is enabled. Updated `DefaultPoolManager` to initialize thread pools with `IVMTaskScheduler` when the JAC mode is active.

Author: iitsoftware

src/main/java/com/swiftmq/client/thread/DefaultPoolManager.java

@@ -23,6 +23,7 @@
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 public class DefaultPoolManager extends PoolManager {
+    public static final String PROP_JAC_ACTIVE = "swiftmq.jac.active";
     public static final String PROP_CONNECTOR_POOL_MIN_THREADS = "swiftmq.pool.connector.threads.min";
     public static final String PROP_CONNECTOR_POOL_MAX_THREADS = "swiftmq.pool.connector.threads.max";
     public static final String PROP_CONNECTOR_POOL_PRIO = "swiftmq.pool.connector.priority";
@@ -45,6 +46,16 @@ public class DefaultPoolManager extends PoolManager {
     ThreadPool connectionPool = null;
     ThreadPool sessionPool = null;
     ThreadPool connectorPool = null;
+    boolean JAC_ACTIVE = System.getProperty(PROP_JAC_ACTIVE, "false").equals("true");
+
+    public DefaultPoolManager() {
+        if (JAC_ACTIVE) {
+            ThreadPool pool = new IVMTaskScheduler();
+            connectionPool = pool;
+            sessionPool = pool;
+            connectorPool = pool;
+        }
+    }
 
     ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
 

src/main/java/com/swiftmq/client/thread/IVMTaskScheduler.java

@@ -0,0 +1,106 @@
+package com.swiftmq.client.thread;
+
+import com.swiftmq.swiftlet.SwiftletManager;
+import com.swiftmq.swiftlet.threadpool.AsyncTask;
+import com.swiftmq.swiftlet.threadpool.ThreadPool;
+import com.swiftmq.swiftlet.threadpool.ThreadpoolSwiftlet;
+import com.swiftmq.swiftlet.threadpool.event.FreezeCompletionListener;
+
+public class IVMTaskScheduler implements ThreadPool {
+
+    ThreadpoolSwiftlet threadpoolSwiftlet = null;
+
+    public IVMTaskScheduler() {
+        threadpoolSwiftlet = (ThreadpoolSwiftlet) SwiftletManager.getInstance().getSwiftlet("sys$threadpool");
+        if (threadpoolSwiftlet == null)
+            System.err.println("[" + this + "] Failed to get ThreadpoolSwiftlet");
+        else
+            System.out.println("[" + this + "] App uses virtual threads, scheduled in: adhocvirtual");
+    }
+
+    /**
+     * Closes the pool.
+     * Internal use only.
+     */
+    @Override
+    public void close() {
+
+    }
+
+    /**
+     * Returns the pool name.
+     *
+     * @return pool name.
+     */
+    @Override
+    public String getPoolName() {
+        return toString();
+    }
+
+    /**
+     * Returns the number of currently idling threads.
+     * Used from management tools only.
+     *
+     * @return number of idling threads.
+     */
+    @Override
+    public int getNumberIdlingThreads() {
+        return 0;
+    }
+
+    /**
+     * Returns the number of currently running threads.
+     * Used from management tools only.
+     *
+     * @return number of running threads.
+     */
+    @Override
+    public int getNumberRunningThreads() {
+        return 0;
+    }
+
+    /**
+     * Dispatch a task into the pool.
+     *
+     * @param asyncTask the task to dispatch.
+     */
+    @Override
+    public void dispatchTask(AsyncTask asyncTask) {
+        threadpoolSwiftlet.runAsync(asyncTask, true);
+    }
+
+    /**
+     * Freezes this pool. That is, the current running tasks are completed but
+     * no further tasks will be scheduled until unfreeze() is called. It is possible
+     * to dispatch tasks during freeze. However, these will be executed after unfreeze()
+     * is called.
+     *
+     * @param listener will be called when the pool is freezed.
+     */
+    @Override
+    public void freeze(FreezeCompletionListener listener) {
+
+    }
+
+    /**
+     * Unfreezes this pool.
+     */
+    @Override
+    public void unfreeze() {
+
+    }
+
+    /**
+     * Stops the pool.
+     * Internal use only.
+     */
+    @Override
+    public void stop() {
+
+    }
+
+    @Override
+    public String toString() {
+        return IVMTaskScheduler.class.getSimpleName();
+    }
+}