wip: use continuation via Loom

Author: oraluben

substratevm/mx.substratevm/suite.py

@@ -272,6 +272,20 @@
         },
 
 
+        "com.oracle.svm.core.jdk19": {
+            "subDir": "src",
+            "sourceDirs": ["src"],
+            "dependencies": ["com.oracle.svm.core"],
+            "requiresConcealed" : {
+                "java.base" : [
+                ],
+            },
+            "javaCompliance": "19+",
+            "checkstyle": "com.oracle.svm.core",
+            "workingSets": "SVM",
+        },
+
+
         "com.oracle.svm.core.genscavenge": {
             "subDir": "src",
             "sourceDirs": [
@@ -1123,6 +1137,7 @@
                 "com.oracle.svm.hosted.jdk17",
                 "com.oracle.svm.core",
                 "com.oracle.svm.core.jdk17",
+                "com.oracle.svm.core.jdk19",
                 "com.oracle.svm.core.graal.amd64",
                 "com.oracle.svm.core.graal.aarch64",
                 "com.oracle.svm.core.posix",

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/thread/LoomVirtualThreads.java renamed to substratevm/src/com.oracle.svm.core.jdk19/src/com/oracle/svm/core/jdk19/LoomVirtualThreads.java

@@ -22,13 +22,16 @@
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
-package com.oracle.svm.core.thread;
+package com.oracle.svm.core.jdk19;
 
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 
 import java.util.concurrent.Executor;
 import java.util.concurrent.ThreadFactory;
 
+import com.oracle.svm.core.thread.Target_java_lang_Thread;
+import com.oracle.svm.core.thread.Target_java_lang_VirtualThread;
+import com.oracle.svm.core.thread.VirtualThreads;
 import org.graalvm.nativeimage.Platforms;
 
 import com.oracle.svm.core.SubstrateUtil;
@@ -49,7 +52,7 @@ private static Target_java_lang_VirtualThread cast(Thread thread) {
 
     @Override
     public ThreadFactory createFactory() {
-        throw VMError.unimplemented();
+        return Thread.ofVirtual().factory();
     }
 
     @Override
@@ -61,7 +64,7 @@ public boolean isVirtual(Thread thread) {
     public void join(Thread thread, long millis) throws InterruptedException {
         if (thread.isAlive()) {
             long nanos = MILLISECONDS.toNanos(millis);
-            cast(thread).joinNanos(nanos);
+//            cast(thread).joinNanos(nanos);
         }
     }
 

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/SubstrateOptions.java

@@ -47,6 +47,7 @@
 import org.graalvm.compiler.options.OptionStability;
 import org.graalvm.compiler.options.OptionType;
 import org.graalvm.compiler.options.OptionValues;
+import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
 import org.graalvm.nativeimage.ImageInfo;
 import org.graalvm.nativeimage.ImageSingletons;
 import org.graalvm.nativeimage.Platform;
@@ -134,11 +135,12 @@ protected void onValueUpdate(EconomicMap<OptionKey<?>, Object> values, Boolean o
     @Option(help = "Support continuations (without requiring a Project Loom JDK)") //
     public static final HostedOptionKey<Boolean> SupportContinuations = new HostedOptionKey<>(false);
 
-    @Option(help = "Build with Project Loom JDK") //
+    @Option(help = "Support continuations via Virtual Threads") //
     public static final HostedOptionKey<Boolean> UseLoom = new HostedOptionKey<>(false) {
         @Override
         protected void onValueUpdate(EconomicMap<OptionKey<?>, Object> values, Boolean oldValue, Boolean newValue) {
             if (newValue) {
+                assert JavaVersionUtil.JAVA_SPEC >= 19;
                 SupportContinuations.update(values, true);
             }
         }

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/thread/ContinuationsFeature.java

@@ -49,23 +49,27 @@ public void afterRegistration(AfterRegistrationAccess access) {
         if (Continuation.isSupported()) {
             VirtualThreads impl;
             if (LoomSupport.isEnabled()) {
-                impl = new LoomVirtualThreads();
+                try {
+                    impl = (VirtualThreads) Class.forName("com.oracle.svm.core.jdk19.LoomVirtualThreads").getDeclaredConstructor().newInstance();
+                } catch (Exception e) {
+                    throw UserError.abort(e, "Error initializing LoomVirtualThreads");
+                }
             } else {
                 /*
                  * GR-37518: ForkJoinPool on 11 syncs on a String which doesn't have its own monitor
                  * field, and unparking a virtual thread in additionalMonitorsLock.unlock causes a
                  * deadlock between carrier thread and virtual thread. 17 uses a ReentrantLock.
                  */
                 UserError.guarantee(JavaVersionUtil.JAVA_SPEC >= 17, "Continuations (%s) are currently supported only on JDK 17 and later.",
-                                SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"));
+                        SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"));
 
                 impl = new SubstrateVirtualThreads();
             }
             ImageSingletons.add(VirtualThreads.class, impl);
         } else {
             UserError.guarantee(!SubstrateOptions.UseLoom.getValue(), "%s cannot be enabled without option %s.",
-                            SubstrateOptionsParser.commandArgument(SubstrateOptions.UseLoom, "+"),
-                            SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"));
+                    SubstrateOptionsParser.commandArgument(SubstrateOptions.UseLoom, "+"),
+                    SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"));
         }
     }
 
@@ -77,7 +81,7 @@ public void beforeAnalysis(BeforeAnalysisAccess access) {
             }
 
             access.registerReachabilityHandler(a -> access.registerAsInHeap(StoredContinuation.class),
-                            ReflectionUtil.lookupMethod(StoredContinuationAccess.class, "allocate", int.class));
+                    ReflectionUtil.lookupMethod(StoredContinuationAccess.class, "allocate", int.class));
 
             if (LoomSupport.isEnabled()) {
                 RuntimeReflection.register(ReflectionUtil.lookupMethod(ForkJoinPool.class, "compensatedBlock", ForkJoinPool.ManagedBlocker.class));
@@ -90,8 +94,8 @@ public void beforeAnalysis(BeforeAnalysisAccess access) {
     static void abortIfUnsupported() {
         if (!Continuation.isSupported()) {
             throw UserError.abort("Continuation support is used, but not enabled. Use options %s or %s.",
-                            SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"),
-                            SubstrateOptionsParser.commandArgument(SubstrateOptions.UseLoom, "+"));
+                    SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"),
+                    SubstrateOptionsParser.commandArgument(SubstrateOptions.UseLoom, "+"));
         }
     }
 }