test/lib/jdk/test/lib/thread/VThreadScheduler.java

*** 21,12 ***
   * questions.
   */
  
  package jdk.test.lib.thread;
  
- import java.lang.reflect.Constructor;
  import java.lang.reflect.Field;
  import java.lang.reflect.InvocationTargetException;
  import java.util.concurrent.Executor;
  import java.util.concurrent.Executors;
  import java.util.concurrent.ThreadFactory;
  
--- 21,12 ---
   * questions.
   */
  
  package jdk.test.lib.thread;
  
  import java.lang.reflect.Field;
+ import java.lang.reflect.Method;
  import java.lang.reflect.InvocationTargetException;
  import java.util.concurrent.Executor;
  import java.util.concurrent.Executors;
  import java.util.concurrent.ThreadFactory;
  

*** 36,21 ***
   * Tests using this class need to open java.base/java.lang.
   */
  public class VThreadScheduler {
      private VThreadScheduler() { }
  
      /**
       * Returns the scheduler for the given virtual thread.
       */
!     public static Executor scheduler(Thread thread) {
          if (!thread.isVirtual())
              throw new IllegalArgumentException("Not a virtual thread");
          try {
              Field scheduler = Class.forName("java.lang.VirtualThread")
                      .getDeclaredField("scheduler");
              scheduler.setAccessible(true);
!             return (Executor) scheduler.get(thread);
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
  
--- 36,41 ---
   * Tests using this class need to open java.base/java.lang.
   */
  public class VThreadScheduler {
      private VThreadScheduler() { }
  
+     /**
+      * Returns the default virtual thread scheduler.
+      */
+     public static Thread.VirtualThreadScheduler defaultScheduler() {
+         try {
+             Method m = Class.forName("java.lang.VirtualThread")
+                     .getDeclaredMethod("defaultScheduler");
+             m.setAccessible(true);
+             return (Thread.VirtualThreadScheduler ) m.invoke(null);
+         } catch (InvocationTargetException e) {
+             Throwable cause = e.getCause();
+             if (cause instanceof RuntimeException re) {
+                 throw re;
+             }
+             throw new RuntimeException(e);
+         } catch (Exception e) {
+             throw new RuntimeException(e);
+         }
+     }
+ 
      /**
       * Returns the scheduler for the given virtual thread.
       */
!     public static Thread.VirtualThreadScheduler scheduler(Thread thread) {
          if (!thread.isVirtual())
              throw new IllegalArgumentException("Not a virtual thread");
          try {
              Field scheduler = Class.forName("java.lang.VirtualThread")
                      .getDeclaredField("scheduler");
              scheduler.setAccessible(true);
!             return (Thread.VirtualThreadScheduler) scheduler.get(thread);
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
  

*** 70,30 ***
  
      /**
       * Returns a builder to create virtual threads that use the given scheduler.
       * @throws UnsupportedOperationException if custom schedulers are not supported
       */
!     public static Thread.Builder.OfVirtual virtualThreadBuilder(Executor scheduler) {
!         try {
!             Class<?> clazz = Class.forName("java.lang.ThreadBuilders$VirtualThreadBuilder");
!             Constructor<?> ctor = clazz.getDeclaredConstructor(Executor.class);
!             ctor.setAccessible(true);
!             return (Thread.Builder.OfVirtual) ctor.newInstance(scheduler);
!         } catch (InvocationTargetException e) {
!             Throwable cause = e.getCause();
!             if (cause instanceof RuntimeException re) {
!                 throw re;
              }
!             throw new RuntimeException(e);
!         } catch (Exception e) {
!             throw new RuntimeException(e);
!         }
      }
  
      /**
       * Returns a ThreadFactory to create virtual threads that use the given scheduler.
       * @throws UnsupportedOperationException if custom schedulers are not supported
       */
!     public static ThreadFactory virtualThreadFactory(Executor scheduler) {
          return virtualThreadBuilder(scheduler).factory();
      }
  }
--- 90,36 ---
  
      /**
       * Returns a builder to create virtual threads that use the given scheduler.
       * @throws UnsupportedOperationException if custom schedulers are not supported
       */
!     @SuppressWarnings("restricted")
!     public static Thread.Builder.OfVirtual virtualThreadBuilder(Thread.VirtualThreadScheduler scheduler) {
!         return Thread.ofVirtual().scheduler(scheduler);
!     }
! 
!     public static Thread.Builder.OfVirtual virtualThreadBuilder(Executor executor) {
!         var scheduler = new Thread.VirtualThreadScheduler() {
!             @Override
!             public void onStart(Thread.VirtualThreadTask task) {
!                 executor.execute(task);
              }
!             @Override
!             public void onContinue(Thread.VirtualThreadTask task) {
!                 executor.execute(task);
!             }
+         };
+         return virtualThreadBuilder(scheduler);
      }
  
      /**
       * Returns a ThreadFactory to create virtual threads that use the given scheduler.
       * @throws UnsupportedOperationException if custom schedulers are not supported
       */
!     public static ThreadFactory virtualThreadFactory(Thread.VirtualThreadScheduler scheduler) {
          return virtualThreadBuilder(scheduler).factory();
      }
+ 
+     public static ThreadFactory virtualThreadFactory(Executor executor) {
+         return virtualThreadBuilder(executor).factory();
+     }
  }