Add Annotation interface for ExecSegment

ratpack-base/src/main/java/ratpack/api/ExecSegment.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2013 the original author or authors.
+ *
+ * Licensed 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 ratpack.api;
+
+import java.lang.annotation.*;
+
+/**
+ * Declares that a method or function-like method parameter is wrapped in an Operation when executed and can freely use <a href="../exec/Promise.html">Promise</a> and other async constructs.
+ * <p>
+ * If this annotation is present on a method, it indicates that the method may be asynchronous.
+ * That is, it is not necessarily expected to have completed its logical work when the method returns.
+ * The method must however use <a href="../exec/Promise.html">Promise</a>, <a href="../exec/Operation.html">Operation</a>, or other execution mechanisms to perform asynchronous work.
+ * <p>
+ * Most such methods are invoked as part of Ratpack.
+ * If you need to invoke such a method, do so as part of a discrete <a href="../exec/Operation.html">Operation</a>.
+ * <p>
+ * If this annotation is present on a function type method parameter, it indicates that the annotated function may be asynchronous.
+ * Similarly, if you need to invoke such a parameter, do so as part of a discrete <a href="../exec/Operation.html">Operation</a>.
+ * <p>
+ *
+ * @since 2.0.0
+ */
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.METHOD, ElementType.PARAMETER})
+public @interface ExecSegment {
+}