From 15ce18ddac0b18e687a13f21ea6e8efde104a45a Mon Sep 17 00:00:00 2001 From: Ladislav Thon Date: Tue, 30 Jan 2024 17:08:05 +0100 Subject: [PATCH] WELD-2765 Introduce WeldInvokerBuilder Upgrade CDI API to Beta1 --- pom.xml | 6 +- .../jboss/weld/invoke/WeldInvokerBuilder.java | 330 ++++++++++++++++++ 2 files changed, 333 insertions(+), 3 deletions(-) create mode 100644 weld/src/main/java/org/jboss/weld/invoke/WeldInvokerBuilder.java diff --git a/pom.xml b/pom.xml index 0269180c..e30f8f96 100644 --- a/pom.xml +++ b/pom.xml @@ -7,11 +7,11 @@ org.jboss.weld weld-parent - 47 + 49 - 3.0 + 3.8 Weld APIs Parent @@ -102,7 +102,7 @@ 2.1.1 2.0.1 - 4.1.0-M1 + 4.1.0.Beta1 4.0.1 3.1.0 3.1.0 diff --git a/weld/src/main/java/org/jboss/weld/invoke/WeldInvokerBuilder.java b/weld/src/main/java/org/jboss/weld/invoke/WeldInvokerBuilder.java new file mode 100644 index 00000000..69021556 --- /dev/null +++ b/weld/src/main/java/org/jboss/weld/invoke/WeldInvokerBuilder.java @@ -0,0 +1,330 @@ +package org.jboss.weld.invoke; + +import jakarta.enterprise.invoke.Invoker; +import jakarta.enterprise.invoke.InvokerBuilder; + +/** + * Builder of {@link Invoker}s that allows configuring input lookups, input and output + * transformations, and invoker wrapping. The method for which the invoker is built is + * called the target method. If a lookup is configured, the corresponding input + * of the invoker is ignored and an instance is looked up from the CDI container before + * the target method is invoked. If a transformation is configured, the corresponding input + * or output of the invoker is modified in certain way before or after the target method + * is invoked. If a wrapper is configured, the invoker is passed to custom code for getting + * invoked. As a result, the built {@code Invoker} instance may have more complex behavior + * than just directly calling the target method. + *

+ * Transformations and wrapping are expressed by ordinary methods that must have + * a pre-defined signature, as described below. Such methods are called + * transformers and wrappers. + *

+ * Invokers may only be built during deployment. It is not possible to build new invokers + * at application runtime. + * + *

Example

+ * + * Before describing in detail how lookups, transformers and wrappers work, let's take + * a look at an example. Say we have the following bean with a method: + * + * 
+ * class MyService {
+ *     String hello(String name) {
+ *         return "Hello " + name + "!";
+ *     }
+ * }
+ *
+ * + * And we want to build an invoker that looks up {@code MyService} from the CDI container, + * always passes the argument to {@code hello()} as all upper-case, and repeats the return + * value twice. To transform the argument, we can use the zero-parameter method + * {@code String.toUpperCase()}, and to transform the return value, we write a transformer + * as a simple {@code static} method: + * + * 
+ * class Transformations {
+ *     static String repeatTwice(String str) {
+ *         return str + " " + str;
+ *     }
+ * }
+ *
+ * + * Then, assuming we have obtained the {@code InvokerBuilder} for {@code MyService.hello()}, + * we can set up the lookup and transformations and build an invoker like so: + * + * 
+ * builder.setInstanceLookup()
+ *         .setArgumentTransformer(0, String.class, "toUpperCase")
+ *         .setReturnValueTransformer(Transformations.class, "repeatTwice")
+ *         .build();
+ *
+ * + * The resulting invoker will be equivalent to the following class: + * + * 
+ * class TheInvoker implements Invoker<MyService, String> {
+ *     String invoke(MyService ignored, Object[] arguments) {
+ *         MyService instance = CDI.current().select(MyService.class).get();
+ *         String argument = (String) arguments[0];
+ *         String transformedArgument = argument.toUpperCase();
+ *         String result = instance.hello(transformedArgument);
+ *         String transformedResult = Transformations.repeatTwice(result);
+ *         return transformedResult;
+ *     }
+ * }
+ *
+ * + * The caller of this invoker may pass {@code null} as the target instance, because + * the invoker will lookup the target instance on its own. Therefore, calling + * {@code invoker.invoke(null, new Object[] {"world"})} will return + * {@code "Hello WORLD! Hello WORLD!"}. + * + *

General requirements

+ * + * To refer to a transformer or a wrapper, all methods in this builder accept: + * 1. the {@code Class} that that declares the method, and 2. the {@code String} name + * of the method. + *

+ * Transformers may be {@code static}, in which case they must be declared directly + * on the given class, or they may be instance methods, in which case they may be declared + * on the given class or inherited from any of its supertypes. + *

+ * It is possible to register only one transformer of each kind, or for each argument + * position in case of argument transformers. Attempting to register a second transformer + * of the same kind, or for the same argument position, leads to an exception. + *

+ * Wrappers must be {@code static} and must be declared directly on the given class. + * It is possible to register only one wrapper. Attempting to register a second wrapper + * leads to an exception. + *

+ * It is a deployment problem if no method with given name and valid signature is found, + * or if multiple methods with given name and different valid signatures are found. It is + * a deployment problem if a registered transformer or wrapper is not {@code public}. + *

+ * Transformers and wrappers may declare the {@code throws} clause. The declared exception + * types are ignored when searching for the method. + *

+ * For the purpose of the specification of transformers and wrappers below, the term + * any-type is recursively defined as: the {@code java.lang.Object} class type, + * or a type variable that has no bound, or a type variable whose first bound is + * any-type. + * + *

Input lookups

+ * + * For the target instance and for each argument, it is possible to specify that the value + * passed to {@code Invoker.invoke()} should be ignored and a value should be looked up + * from the CDI container instead. + *

+ * For the target instance, a CDI lookup is performed with the required type equal to the bean + * class of the bean to which the target method belongs, and required qualifiers equal to the set + * of all qualifier annotations present on the bean class of the bean to which the target method + * belongs. When the target method is {@code static}, the target instance lookup is skipped. + *

+ * For an argument, a CDI lookup is performed with the required type equal to the type of + * the corresponding parameter of the target method, and required qualifiers equal to the set + * of all qualifier annotations present on the corresponding parameter of the target method. + *

+ * Implementations are required to resolve all lookups during deployment. It is a deployment + * problem if the lookup ends up unresolved or ambiguous. + *

+ * If the looked up bean is {@code @Dependent}, it is guaranteed that the instance will be + * destroyed after the target method is invoked but before the the invoker returns. The order + * in which the looked up {@code @Dependent} beans are destroyed is not specified. + *

+ * The order in which input lookups are performed in not specified and must not be relied upon. + * + *

Input transformations

+ * + * The target method has 2 kinds of inputs: the target instance (unless the target method is + * {@code static}, in which case the target instance is ignored and should be {@code null} + * by convention) and arguments. These inputs correspond to the parameters of + * {@link Invoker#invoke(Object, Object[]) Invoker.invoke()}. + *

+ * Each input can be transformed by a transformer that has one of the following signatures, + * where {@code X} and {@code Y} are types: + * + *

+ * + * An input transformer must produce a type that can be consumed by the target method. + * Specifically: when {@code X} is any-type, it is not type checked during deployment. + * Otherwise, it is a deployment problem if {@code X} is not assignable to the corresponding type + * in the declaration of the target method (that is the bean class in case of target instance + * transformers, or the corresponding parameter type in case of argument transformers). {@code Y} + * is not type checked during deployment, so that input transformers may consume arbitrary types. + *

+ * When a transformer is registered for given input, it is called before the target method is + * invoked, and the outcome of the transformer is used in the invocation instead of the original + * value passed to the invoker by its caller. + *

+ * If the transformer declares the {@code Consumer} parameter, and the execution + * of the transformer calls {@code Consumer.accept()} with some {@code Runnable}, it is + * guaranteed that the {@code Runnable} will be called after the target method is invoked but + * before the invoker returns. These {@code Runnable}s are called cleanup tasks. + * The order of cleanup task execution is not specified. Passing a {@code null} cleanup task + * to the {@code Consumer} is permitted, but has no effect. + *

+ * If an input transformation is configured for an input for which a lookup is also configured, + * the lookup is performed first and the transformation is applied to the looked up value. + * If the looked up bean for some input is {@code @Dependent}, it is guaranteed that all + * cleanup tasks registered by a transformer for that input are called before that looked up + * {@code @Dependent} bean is destroyed. + *

+ * The order in which input transformations are performed in not specified and must not + * be relied upon. + * + *

Output transformations

+ * + * The target method has 2 kinds of outputs: the return value and the thrown exception. These + * outputs correspond to the return value of {@link Invoker#invoke(Object, Object[]) Invoker.invoke()} + * or its thrown exception, respectively. + *

+ * Each output can be transformed by a transformer that has one of the following signatures, + * where {@code X} and {@code Y} are types: + * + *

+ * + * An output transformer must consume a type that can be produced by the target method. + * Specifically: when {@code Y} is any-type, it is not type checked during deployment. + * Otherwise, it is a deployment problem if {@code Y} is not assignable from the return type of + * the target method in case of return value transformers, or from {@code java.lang.Throwable} + * in case of exception transformers. {@code X} is not type checked during deployment, so that + * output transformers may produce arbitrary types. + *

+ * When a transformer is registered for given output, it is called after the target method + * is invoked, and the outcome of the transformer is passed back to the caller of the invoker + * instead of the original output produced by the target method. + *

+ * If the target method returns normally, any registered exception transformer is ignored; only + * the return value transformer is called. The return value transformer may throw, in which case + * the invoker will rethrow the exception. If the invoker is supposed to return normally, + * the return value transformer must return normally. + *

+ * Similarly, if the target method throws, any registered return value transformer is ignored; + * only the exception transformer is called. The exception transformer may return normally, + * in which case the invoker will return the return value of the exception transformer. If + * the invoker is supposed to throw an exception, the exception transformer must throw. + * + *

Invoker wrapping

+ * + * An invoker, possibly utilizing input lookups and input/output transformations, may be wrapped + * by a custom piece of code for maximum flexibility. A wrapper must have the following signature, + * where {@code X}, {@code Y} and {@code Z} are types: + * + * + * + * A wrapper must operate on a matching instance type. Specifically: when {@code X} is + * any-type, it is not type checked during deployment. Otherwise, it is a deployment + * problem if {@code X} is not assignable from the class type of the bean class to which + * the target method belongs. {@code Y} and {@code Z} are not type checked during deployment. + *

+ * When a wrapper is registered, 2 invokers for the same method are created. The inner + * invoker applies all lookups and transformations, as described in previous sections, and + * invokes the target method. The outer invoker calls the wrapper with the passed + * instance and arguments and an instance of the inner invoker. The outer invoker is returned + * by this invoker builder. + *

+ * In other words, the outer invoker is equivalent to the following class: + * + * 

+ * class InvokerWrapper implements Invoker<X, Z> {
+ *     Z invoke(X instance, Object[] arguments) {
+ *         // obtain the invoker as if no wrapper existed
+ *         Invoker<X, Y> invoker = obtainInvoker();
+ *         return SomeClass.wrap(instance, arguments, invoker);
+ *     }
+ * }
+ *
+ * + * If the wrapper returns normally, the outer invoker returns its return value, unless the wrapper + * is declared {@code void}, in which case the outer invoker returns {@code null}. If the wrapper + * throws an exception, the outer invoker rethrows it directly. + *

+ * The wrapper is supposed to call the invoker it is passed, but does not necessarily have to. + * The wrapper may call the invoker multiple times. The wrapper must not use the invoker + * in any other way; specifically, it is forbidden to store the invoker instance anywhere + * or pass it to other methods that do not follow these rules. Doing so leads to non-portable + * behavior. + * + *

Type checking

+ * + * An invoker created by this builder has relaxed type checking rules, when compared to + * the description in {@link Invoker#invoke(Object, Object[]) Invoker.invoke()}, depending + * on configured lookups, transformers and wrapper. Some types are checked during + * deployment, as described in previous sections. Other types are checked during invocation, + * at the very least due to the type checks performed implicitly by the JVM. The lookups, + * transformers and the wrapper must arrange the inputs and outputs so that when the method + * is eventually invoked, the rules described in + */ +public interface WeldInvokerBuilder extends InvokerBuilder { + @Override + WeldInvokerBuilder withInstanceLookup(); + + @Override + WeldInvokerBuilder withArgumentLookup(int position); + + /** + * Registers a transformer for the instance on which the invoker will be called. + *

+ * Transformer method needs to be a static method of an accessible class. + * + * @param clazz Class which declares the transformer method + * @param methodName transformer method name represented as a String + * @return self + */ + WeldInvokerBuilder withInstanceTransformer(Class clazz, String methodName); + + /** + * Registers a transformer for a single argument of the target method. + *

+ * Transformer method needs to be a static method of an accessible class. + * + * @param position position of an argument in the invoker's target method that should be transformed + * @param clazz Class which declares the transformer method + * @param methodName transformer method name represented as a String + * @return self + */ + WeldInvokerBuilder withArgumentTransformer(int position, Class clazz, String methodName); + + /** + * Registers a transformer for return value of the target method. + *

+ * Transformer method needs to be a static method of an accessible class. + * + * @param clazz Class which declares the transformer method + * @param methodName transformer method name represented as a String + * @return self + */ + WeldInvokerBuilder withReturnValueTransformer(Class clazz, String methodName); + + /** + * Registers an exception transformer for a possible exception thrown by the target method. + *

+ * Transformer method needs to be a static method of an accessible class. + * + * @param clazz Class which declares the transformer method + * @param methodName transformer method name represented as a String + * @return self + */ + WeldInvokerBuilder withExceptionTransformer(Class clazz, String methodName); + + /** + * Registers an invocation wrapper for given invoker. + *

+ * Transformer method needs to be a static method of an accessible class. + * + * @param clazz Class which declares the transformer method + * @param methodName transformer method name represented as a String + * @return self + */ + WeldInvokerBuilder withInvocationWrapper(Class clazz, String methodName); +}