GROOVY-9381: Support async/await like ES7(backend)

Author: daniellansun

src/main/groovy/groovy/transform/Async.groovy

@@ -0,0 +1,40 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package groovy.transform
+
+import groovy.transform.stc.POJO
+
+import java.lang.annotation.Documented
+import java.lang.annotation.ElementType
+import java.lang.annotation.Retention
+import java.lang.annotation.RetentionPolicy
+import java.lang.annotation.Target
+
+/**
+ * Annotation used to mark async methods, closures and lambda expressions.
+ *
+ * @since 6.0.0
+ */
+@POJO
+@CompileStatic
+@Retention(RetentionPolicy.SOURCE)
+@Target([ElementType.METHOD, ElementType.LOCAL_VARIABLE, ElementType.FIELD])
+@Documented
+@interface Async {
+}

src/main/java/groovy/util/concurrent/async/AsyncHelper.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package groovy.util.concurrent.async;
+
+import org.apache.groovy.util.SystemUtil;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.function.Supplier;
+
+/**
+ * Helper class for async/await operations
+ *
+ * @since 6.0.0
+ */
+public class AsyncHelper {
+    private static final int PARALLELISM = SystemUtil.getIntegerSafe("groovy.async.parallelism", Runtime.getRuntime().availableProcessors() + 1);
+    private static final Executor DEFAULT_EXECUTOR;
+    private static int seq;
+
+    static {
+        Executor tmpExecutor;
+        try {
+            MethodHandles.Lookup lookup = MethodHandles.lookup();
+            MethodHandle mh = lookup.findStatic(
+                Executors.class,
+                "newVirtualThreadPerTaskExecutor",
+                MethodType.methodType(ExecutorService.class)
+            );
+            tmpExecutor = (Executor) mh.invoke();
+        } catch (Throwable throwable) {
+            // Fallback to default thread pool if virtual threads are not available
+            tmpExecutor = Executors.newFixedThreadPool(PARALLELISM, r -> {
+                Thread t = new Thread(r);
+                t.setName("async-thread-" + seq++);
+                return t;
+            });
+        }
+        DEFAULT_EXECUTOR = tmpExecutor;
+    }
+
+    /**
+     * Submits a supplier for asynchronous execution using the default executor
+     *
+     * @param supplier the supplier
+     * @param <T>      the result type
+     * @return the promise
+     */
+    public static <T> Promise<T> async(Supplier<T> supplier) {
+        return SimplePromise.of(supplier, DEFAULT_EXECUTOR);
+    }
+
+    /**
+     * Submits a supplier for asynchronous execution using the provided executor
+     *
+     * @param supplier the supplier
+     * @param executor the executor
+     * @param <T>      the result type
+     * @return the promise
+     */
+    public static <T> Promise<T> async(Supplier<T> supplier, Executor executor) {
+        return SimplePromise.of(supplier, executor);
+    }
+
+    /**
+     * Awaits the result of an awaitable
+     *
+     * @param awaitable the awaitable
+     * @param <T>       the result type
+     * @return the result
+     */
+    public static <T> T await(Awaitable<T> awaitable) {
+        return awaitable.await();
+    }
+
+    private AsyncHelper() {}
+}

src/main/java/groovy/util/concurrent/async/AwaitException.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package groovy.util.concurrent.async;
+
+/**
+ * Exception thrown when attempting to wait for the result of a promise
+ * that aborted by throwing an exception. This exception can be
+ * inspected using the {@link #getCause()} method.
+ *
+ * @see Promise
+ * @since 6.0.0
+ */
+public class AwaitException extends RuntimeException {
+    public AwaitException() {
+    }
+
+    public AwaitException(String message) {
+        super(message);
+    }
+
+    public AwaitException(Throwable cause) {
+        super(cause);
+    }
+
+    public AwaitException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

src/main/java/groovy/util/concurrent/async/Awaitable.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package groovy.util.concurrent.async;
+
+/**
+ * Represents a result of an asynchronous computation
+ *
+ * @since 6.0.0
+ */
+public interface Awaitable<T> {
+    /**
+     * Waits if necessary for the computation to complete, and then retrieves its
+     * result.
+     *
+     * @return the computed result
+     * @throws AwaitException if the computation was cancelled or completed
+     */
+    T await();
+}