8287186: JDK modules participating in preview

Reviewed-by: alanb, jlahoda

Author: Paul Sandoz

src/java.base/share/classes/jdk/internal/javac/ParticipatesInPreview.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.internal.javac;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Indicates, when declared on a module declaration, that the module participates
+ * in preview features and therefore does not need to be compiled with "--enable-preview".
+ */
+@Target(ElementType.MODULE)
+@Retention(RetentionPolicy.CLASS)
+public @interface ParticipatesInPreview {
+}

src/java.base/share/classes/module-info.java

@@ -141,9 +141,17 @@
         jdk.compiler;
     exports com.sun.security.ntlm to
         java.security.sasl;
+    // Note: all modules in the exported list participate in preview  features
+    // and therefore if they use preview features they do not need to be
+    // compiled with "--enable-preview".
+    // It is recommended for any modules that do participate that their
+    // module declaration be annotated with jdk.internal.javac.ParticipatesInPreview
     exports jdk.internal.javac to
         java.compiler,
+        java.management, // participates in preview features
         jdk.compiler,
+        jdk.incubator.concurrent, // participates in preview features
+        jdk.incubator.vector, // participates in preview features
         jdk.jdi,
         jdk.jfr,
         jdk.jshell,

src/java.management/share/classes/java/lang/management/ThreadInfo.java

@@ -29,8 +29,6 @@
 import javax.management.openmbean.CompositeData;
 import sun.management.ManagementFactoryHelper;
 import sun.management.ThreadInfoCompositeData;
-import sun.management.Util;
-import static java.lang.Thread.State.*;
 
 /**
  * Thread information. {@code ThreadInfo} contains the information
@@ -226,7 +224,7 @@ private void initialize(Thread t, int state, Object lockObj, Thread lockOwner,
                             StackTraceElement[] stackTrace,
                             MonitorInfo[] lockedMonitors,
                             LockInfo[] lockedSynchronizers) {
-        this.virtual = Util.isVirtual(t);
+        this.virtual = t.isVirtual();
         this.threadId = t.threadId();
         this.threadName = t.getName();
         this.threadState = ManagementFactoryHelper.toThreadState(state);

src/java.management/share/classes/module-info.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,6 +23,8 @@
  * questions.
  */
 
+import jdk.internal.javac.ParticipatesInPreview;
+
 /**
  * Defines the Java Management Extensions (JMX) API.
  * <P>
@@ -35,6 +37,7 @@
  * @moduleGraph
  * @since 9
  */
+@ParticipatesInPreview
 module java.management {
 
     exports java.lang.management;

src/java.management/share/classes/sun/management/ThreadImpl.java

@@ -31,7 +31,6 @@
 import java.util.stream.Stream;
 import javax.management.ObjectName;
 import java.util.Objects;
-import sun.management.Util;
 
 /**
  * Implementation for java.lang.management.ThreadMXBean as well as providing the
@@ -222,7 +221,7 @@ public void setThreadContentionMonitoringEnabled(boolean enable) {
 
     private boolean verifyCurrentThreadCpuTime() {
         // check if Thread CPU time measurement is supported.
-        if (Util.isVirtual(Thread.currentThread())) {
+        if (Thread.currentThread().isVirtual()) {
             throw new UnsupportedOperationException("Not supported by virtual threads");
         }
         if (!isCurrentThreadCpuTimeSupported()) {
@@ -284,7 +283,7 @@ protected long[] getThreadCpuTime(long[] ids) {
                 long id = ids[0];
                 Thread thread = Thread.currentThread();
                 if (id == thread.threadId()) {
-                    if (Util.isVirtual(thread)) {
+                    if (thread.isVirtual()) {
                         times[0] = -1;
                     } else {
                         times[0] = getThreadTotalCpuTime0(0);
@@ -327,7 +326,7 @@ protected long[] getThreadUserTime(long[] ids) {
                 long id = ids[0];
                 Thread thread = Thread.currentThread();
                 if (id == thread.threadId()) {
-                    if (Util.isVirtual(thread)) {
+                    if (thread.isVirtual()) {
                         times[0] = -1;
                     } else {
                         times[0] = getThreadUserCpuTime0(0);
@@ -361,7 +360,7 @@ public void setThreadCpuTimeEnabled(boolean enable) {
     }
 
     protected long getCurrentThreadAllocatedBytes() {
-        if (isThreadAllocatedMemoryEnabled() && !Util.isVirtual(Thread.currentThread())) {
+        if (isThreadAllocatedMemoryEnabled() && !Thread.currentThread().isVirtual()) {
             return getThreadAllocatedMemory0(0);
         }
         return -1;
@@ -377,7 +376,7 @@ protected long getThreadAllocatedBytes(long id) {
         if (verified) {
             Thread thread = Thread.currentThread();
             if (id == thread.threadId()) {
-                if (Util.isVirtual(thread)) {
+                if (thread.isVirtual()) {
                     return -1L;
                 } else {
                     return getThreadAllocatedMemory0(0);
@@ -577,7 +576,7 @@ public ObjectName getObjectName() {
      */
     private static long[] platformThreadIds(Thread[] threads) {
         return Stream.of(threads)
-                .filter(t -> !Util.isVirtual(t))
+                .filter(t -> !t.isVirtual())
                 .mapToLong(Thread::threadId)
                 .toArray();
     }

src/java.management/share/classes/sun/management/Util.java

@@ -25,7 +25,6 @@
 
 package sun.management;
 
-import java.lang.reflect.Method;
 import java.lang.reflect.Field;
 import java.lang.management.ManagementPermission;
 import java.lang.management.ThreadInfo;
@@ -88,20 +87,6 @@ public static void checkControlAccess() throws SecurityException {
         checkAccess(controlPermission);
     }
 
-    /**
-     * Returns true if the given Thread is a virtual thread.
-     *
-     * @implNote This method uses reflection because Thread::isVirtual is a preview API
-     * and the java.management module cannot be compiled with --enable-preview.
-     */
-    public static boolean isVirtual(Thread thread) {
-        try {
-            return (boolean) THREAD_IS_VIRTUAL.invoke(thread);
-        } catch (Exception e) {
-            throw new InternalError(e);
-        }
-    }
-
     /**
      * Returns true if the given ThreadInfo is for a virtual thread.
      */
@@ -113,16 +98,6 @@ public static boolean isVirtual(ThreadInfo threadInfo) {
         }
     }
 
-    @SuppressWarnings("removal")
-    private static Method threadIsVirtual() {
-        PrivilegedExceptionAction<Method> pa = () -> Thread.class.getMethod("isVirtual");
-        try {
-            return AccessController.doPrivileged(pa);
-        } catch (PrivilegedActionException e) {
-            throw new InternalError(e);
-        }
-    }
-
     @SuppressWarnings("removal")
     private static Field threadInfoVirtual() {
         PrivilegedExceptionAction<Field> pa = () -> {
@@ -137,6 +112,5 @@ private static Field threadInfoVirtual() {
         }
     }
 
-    private static final Method THREAD_IS_VIRTUAL = threadIsVirtual();
     private static final Field THREADINFO_VIRTUAL = threadInfoVirtual();
 }

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Preview.java

@@ -124,15 +124,22 @@ private Map<Integer, Source> initMajorVersionToSourceMap() {
      * Returns true if {@code s} is deemed to participate in the preview of {@code previewSymbol}, and
      * therefore no warnings or errors will be produced.
      *
+     * @parem syms the symbol table
      * @param s the symbol depending on the preview symbol
      * @param previewSymbol the preview symbol marked with @Preview
      * @return true if {@code s} is participating in the preview of {@code previewSymbol}
      */
-    public boolean participatesInPreview(Symbol s, Symbol previewSymbol) {
-        // Hardcode the incubating vector API module for now
-        // Will generalize with an annotation, @PreviewParticipating say, later
-        return previewSymbol.packge().modle == s.packge().modle ||
-                s.packge().modle.name == names.jdk_incubator_vector;
+    public boolean participatesInPreview(Symtab syms, Symbol s, Symbol previewSymbol) {
+        // All symbols in the same module as the preview symbol participate in the preview API
+        if (previewSymbol.packge().modle == s.packge().modle) {
+            return true;
+        }
+
+        // If java.base's jdk.internal.javac package is exported to s's module then
+        // s participates in the preview API
+        return syms.java_base.exports.stream()
+                .filter(ed -> ed.packge.fullname == names.jdk_internal_javac)
+                .anyMatch(ed -> ed.modules.contains(s.packge().modle));
     }
 
     /**

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java

@@ -3600,7 +3600,7 @@ void checkProfile(final DiagnosticPosition pos, final Symbol s) {
     }
 
     void checkPreview(DiagnosticPosition pos, Symbol other, Symbol s) {
-        if ((s.flags() & PREVIEW_API) != 0 && !preview.participatesInPreview(other, s)) {
+        if ((s.flags() & PREVIEW_API) != 0 && !preview.participatesInPreview(syms, other, s)) {
             if ((s.flags() & PREVIEW_REFLECTIVE) == 0) {
                 if (!preview.isEnabled()) {
                     log.error(pos, Errors.IsPreview(s));

src/jdk.compiler/share/classes/com/sun/tools/javac/util/Names.java

@@ -120,11 +120,11 @@ public static Names instance(Context context) {
     // package names
     public final Name java;
     public final Name java_lang;
+    public final Name jdk_internal_javac;
 
     // module names
     public final Name java_base;
     public final Name jdk_unsupported;
-    public final Name jdk_incubator_vector;
 
     // attribute names
     public final Name Annotation;
@@ -302,11 +302,11 @@ public Names(Context context) {
         // package names
         java = fromString("java");
         java_lang = fromString("java.lang");
+        jdk_internal_javac = fromString("jdk.internal.javac");
 
         // module names
         java_base = fromString("java.base");
         jdk_unsupported = fromString("jdk.unsupported");
-        jdk_incubator_vector = fromString("jdk.incubator.vector");
 
         // attribute names
         Annotation = fromString("Annotation");

src/jdk.incubator.concurrent/share/classes/jdk/incubator/concurrent/StructuredTaskScope.java

@@ -26,7 +26,6 @@
 
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.VarHandle;
-import java.lang.reflect.Method;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
 import java.time.Duration;
@@ -300,7 +299,7 @@ public StructuredTaskScope(String name, ThreadFactory factory) {
      */
     public StructuredTaskScope() {
         PreviewFeatures.ensureEnabled();
-        this.factory = FactoryHolder.VIRTUAL_THREAD_FACTORY;
+        this.factory = Thread.ofVirtual().factory();
         this.flock = ThreadFlock.open(null);
     }
 
@@ -839,7 +838,7 @@ public ShutdownOnSuccess(String name, ThreadFactory factory) {
          * name of {@code null} and a thread factory that creates virtual threads.
          */
         public ShutdownOnSuccess() {
-            super(null, FactoryHolder.VIRTUAL_THREAD_FACTORY);
+            super(null, Thread.ofVirtual().factory());
         }
 
         /**
@@ -1015,7 +1014,7 @@ public ShutdownOnFailure(String name, ThreadFactory factory) {
          * name of {@code null} and a thread factory that creates virtual threads.
          */
         public ShutdownOnFailure() {
-            super(null, FactoryHolder.VIRTUAL_THREAD_FACTORY);
+            super(null, Thread.ofVirtual().factory());
         }
 
         /**
@@ -1161,29 +1160,4 @@ void throwIfFailed(Function<Throwable, ? extends X> esf) throws X {
             }
         }
     }
-
-    /**
-     * Holder class for the virtual thread factory. It uses reflection to allow
-     * this class be compiled in an incubator module without also enabling preview
-     * features.
-     */
-    private static class FactoryHolder {
-        static final ThreadFactory VIRTUAL_THREAD_FACTORY = virtualThreadFactory();
-
-        @SuppressWarnings("removal")
-        private static ThreadFactory virtualThreadFactory() {
-            PrivilegedAction<ThreadFactory> pa = () -> {
-                try {
-                    Method ofVirtualMethod = Thread.class.getDeclaredMethod("ofVirtual");
-                    Object virtualThreadBuilder = ofVirtualMethod.invoke(null);
-                    Class<?> ofVirtualClass = Class.forName("java.lang.Thread$Builder$OfVirtual");
-                    Method factoryMethod = ofVirtualClass.getMethod("factory");
-                    return (ThreadFactory) factoryMethod.invoke(virtualThreadBuilder);
-                } catch (Exception e) {
-                    throw new InternalError(e);
-                }
-            };
-            return AccessController.doPrivileged(pa);
-        }
-    }
 }

src/jdk.incubator.concurrent/share/classes/module-info.java

@@ -23,12 +23,15 @@
  * questions.
  */
 
+import jdk.internal.javac.ParticipatesInPreview;
+
 /**
  * Defines non-final APIs for concurrent programming.
  * {@Incubating}
  *
  * @moduleGraph
  */
+@ParticipatesInPreview
 module jdk.incubator.concurrent {
     exports jdk.incubator.concurrent;
 }

src/jdk.incubator.vector/share/classes/module-info.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,6 +23,8 @@
  * questions.
  */
 
+import jdk.internal.javac.ParticipatesInPreview;
+
 /**
  * Defines an API for expressing computations that can be reliably compiled
  * at runtime into SIMD instructions, such as AVX instructions on x64, and
@@ -31,6 +33,7 @@
  *
  * @moduleGraph
  */
+@ParticipatesInPreview
 module jdk.incubator.vector {
     exports jdk.incubator.vector;
 }