8338383: Implement JEP 491: Synchronize Virtual Threads without Pinning

Co-authored-by: Patricio Chilano Mateo <pchilanomate@openjdk.org>
Co-authored-by: Alan Bateman <alanb@openjdk.org>
Co-authored-by: Andrew Haley <aph@openjdk.org>
Co-authored-by: Fei Yang <fyang@openjdk.org>
Co-authored-by: Coleen Phillimore <coleenp@openjdk.org>
Co-authored-by: Richard Reingruber <rrich@openjdk.org>
Co-authored-by: Martin Doerr <mdoerr@openjdk.org>
Reviewed-by: aboldtch, dholmes, coleenp, fbredberg, dlong, sspitsyn

src/java.base/share/classes/sun/nio/ch/Poller.java

@@ -26,7 +26,9 @@ package sun.nio.ch;
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
@@ -40,7 +42,7 @@ import sun.security.action.GetPropertyAction;
  * Polls file descriptors. Virtual threads invoke the poll method to park
  * until a given file descriptor is ready for I/O.
  */
-abstract class Poller {
+public abstract class Poller {
     private static final Pollers POLLERS;
     static {
         try {
@@ -142,6 +144,20 @@ abstract class Poller {
         }
     }
 
+    /**
+     * Parks the current thread until a Selector's file descriptor is ready.
+     * @param fdVal the Selector's file descriptor
+     * @param nanos the waiting time or 0 to wait indefinitely
+     */
+    static void pollSelector(int fdVal, long nanos) throws IOException {
+        assert nanos >= 0L;
+        Poller poller = POLLERS.masterPoller();
+        if (poller == null) {
+            poller = POLLERS.readPoller(fdVal);
+        }
+        poller.poll(fdVal, nanos, () -> true);
+    }
+
     /**
      * If there is a thread polling the given file descriptor for the given event then
      * the thread is unparked.
@@ -258,6 +274,18 @@ abstract class Poller {
         }
     }
 
+    /**
+     * Returns the number I/O operations currently registered with this poller.
+     */
+    public int registered() {
+        return map.size();
+    }
+
+    @Override
+    public String toString() {
+        return Objects.toIdentityString(this) + " [registered = " + registered() + "]";
+    }
+
     /**
      * The Pollers used for read and write events.
      */
@@ -344,6 +372,13 @@ abstract class Poller {
             }
         }
 
+        /**
+         * Returns the master poller, or null if there is no master poller.
+         */
+        Poller masterPoller() {
+            return masterPoller;
+        }
+
         /**
          * Returns the read poller for the given file descriptor.
          */
@@ -360,6 +395,21 @@ abstract class Poller {
             return writePollers[index];
         }
 
+        /**
+         * Return the list of read pollers.
+         */
+        List<Poller> readPollers() {
+            return List.of(readPollers);
+        }
+
+        /**
+         * Return the list of write pollers.
+         */
+        List<Poller> writePollers() {
+            return List.of(writePollers);
+        }
+
+
         /**
          * Reads the given property name to get the poller count. If the property is
          * set then the value must be a power of 2. Returns 1 if the property is not

src/java.base/share/classes/sun/security/ssl/X509TrustManagerImpl.java

@@ -25,6 +25,7 @@
 
 package sun.security.ssl;
 
+import java.lang.invoke.MethodHandles;
 import java.net.Socket;
 import java.security.*;
 import java.security.cert.*;
@@ -51,6 +52,15 @@ import sun.security.validator.*;
 final class X509TrustManagerImpl extends X509ExtendedTrustManager
         implements X509TrustManager {
 
+    static {
+        // eagerly initialize to avoid pinning virtual thread during TLS handshake
+        try {
+            MethodHandles.lookup().ensureInitialized(AnchorCertificates.class);
+        } catch (IllegalAccessException e) {
+            throw new ExceptionInInitializerError(e);
+        }
+    }
+
     private final String validatorType;
 
     /**