Removed Scheduler's reflective lookup of delayedExecutor

caffeine/src/main/java/com/github/benmanes/caffeine/cache/Scheduler.java

@@ -18,8 +18,6 @@
 import static java.util.Objects.requireNonNull;
 
 import java.io.Serializable;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
@@ -32,7 +30,6 @@
 
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.nullness.qual.NonNull;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A scheduler that submits a task to an executor after a given delay.
@@ -64,15 +61,13 @@ public interface Scheduler {
   }
 
   /**
-   * Returns a scheduler that uses the system-wide scheduling thread if available, or else returns
-   * {@link #disabledScheduler()} if not present. This scheduler is provided in Java 9 or above
-   * by using {@link CompletableFuture} {@code delayedExecutor}.
+   * Returns a scheduler that uses the system-wide scheduling thread by using
+   * {@link CompletableFuture#delayedExecutor}.
    *
-   * @return a scheduler that uses the system-wide scheduling thread if available, or else a
-   *         disabled scheduler
+   * @return a scheduler that uses the system-wide scheduling thread
    */
   static @NonNull Scheduler systemScheduler() {
-    return SystemScheduler.isPresent() ? SystemScheduler.INSTANCE : disabledScheduler();
+    return SystemScheduler.INSTANCE;
   }
 
   /**
@@ -101,35 +96,10 @@ public interface Scheduler {
 enum SystemScheduler implements Scheduler {
   INSTANCE;
 
-  static final @Nullable Method delayedExecutor = getDelayedExecutorMethod();
-
   @Override
-  @SuppressWarnings("NullAway")
   public Future<?> schedule(Executor executor, Runnable command, long delay, TimeUnit unit) {
-    requireNonNull(executor);
-    requireNonNull(command);
-    requireNonNull(unit);
-
-    try {
-      Executor scheduler = (Executor) delayedExecutor.invoke(
-          CompletableFuture.class, delay, unit, executor);
-      return CompletableFuture.runAsync(command, scheduler);
-    } catch (IllegalAccessException | InvocationTargetException e) {
-      throw new RuntimeException(e);
-    }
-  }
-
-  static @Nullable Method getDelayedExecutorMethod() {
-    try {
-      return CompletableFuture.class.getMethod(
-          "delayedExecutor", long.class, TimeUnit.class, Executor.class);
-    } catch (NoSuchMethodException | SecurityException e) {
-      return null;
-    }
-  }
-
-  static boolean isPresent() {
-    return (delayedExecutor != null);
+    Executor delayedExecutor = CompletableFuture.delayedExecutor(delay, unit, executor);
+    return CompletableFuture.runAsync(command, delayedExecutor);
   }
 }
 

caffeine/src/test/java/com/github/benmanes/caffeine/cache/SchedulerTest.java

@@ -36,7 +36,6 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.LogManager;
 
-import org.apache.commons.lang3.SystemUtils;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Mockito;
 import org.testng.annotations.DataProvider;
@@ -58,14 +57,6 @@ public final class SchedulerTest {
 
   private final NullPointerTester npeTester = new NullPointerTester();
 
-  @Test
-  public void hasSystemScheduler() {
-    Scheduler scheduler = SystemUtils.IS_JAVA_1_8
-        ? Scheduler.disabledScheduler()
-        : SystemScheduler.INSTANCE;
-    assertThat(Scheduler.systemScheduler(), is(scheduler));
-  }
-
   @Test(dataProvider = "schedulers")
   public void scheduler_null(Scheduler scheduler) {
     npeTester.testAllPublicInstanceMethods(scheduler);