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Metric grouping via @MetricGroup annotation (#33)
* Initial add of metric group annotation * Add class level default to handling * Utility to scan class for annotations on parent classes and interfaces * Fix parent annotation tracking inside Handler and tests * Test variations for AnnotationHelper * Document annotation helper * Implement global prefix across instrumented interfaces
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...etrics/src/main/java/com/palantir/tritium/event/metrics/annotations/AnnotationHelper.java
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| /* | ||
| * Copyright 2017 Palantir Technologies, Inc. All rights reserved. | ||
| * | ||
| * 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. | ||
| */ | ||
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| package com.palantir.tritium.event.metrics.annotations; | ||
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| import static com.google.common.base.Preconditions.checkNotNull; | ||
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| import com.google.common.annotations.VisibleForTesting; | ||
| import com.google.common.collect.ImmutableSet; | ||
| import java.lang.annotation.Annotation; | ||
| import java.lang.reflect.Method; | ||
| import java.util.Arrays; | ||
| import java.util.Set; | ||
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| public final class AnnotationHelper { | ||
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| private AnnotationHelper() { | ||
| throw new UnsupportedOperationException(); | ||
| } | ||
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| /** | ||
| * Annotation as implemented on passed in type or parent of that type, works for both super classes and interfaces. | ||
| * | ||
| * @param clazz - Class type to scan for annotations | ||
| * @param annotation - Annotation type to scan for | ||
| * @return - First matching annotation found in depth first search, or null if not found | ||
| */ | ||
| public static <T extends Annotation> T getSuperTypeAnnotation(Class<?> clazz, Class<T> annotation) { | ||
| if (clazz.isAnnotationPresent(annotation)) { | ||
| return clazz.getAnnotation(annotation); | ||
| } | ||
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| for (Class<?> ifaces : getParentClasses(clazz)) { | ||
| T superAnnotation = getSuperTypeAnnotation(ifaces, annotation); | ||
| if (superAnnotation != null) { | ||
| return superAnnotation; | ||
| } | ||
| } | ||
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| return null; | ||
| } | ||
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| /** | ||
| * Depth first search up the Type hierarchy to find a matching annotation, Types which do not implement the | ||
| * specified method signature are ignored. | ||
| * | ||
| * @param annotation - Annotation type to scan for | ||
| * @param clazz - Class type to scan for matching annotations | ||
| * @param methodSignature - Method to search annotation for | ||
| * @return - First found matching annotation or null | ||
| */ | ||
| public static <T extends Annotation> T getMethodAnnotation( | ||
| Class<T> annotation, Class<?> clazz, MethodSignature methodSignature) { | ||
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| Method method; | ||
| try { | ||
| method = clazz.getMethod(methodSignature.getMethodName(), methodSignature.getParameterTypes()); | ||
| } catch (NoSuchMethodException e) { | ||
| return null; | ||
| } | ||
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| if (method.isAnnotationPresent(annotation)) { | ||
| return method.getAnnotation(annotation); | ||
| } | ||
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| for (Class<?> iface : getParentClasses(clazz)) { | ||
| T foundAnnotation = getMethodAnnotation(annotation, iface, methodSignature); | ||
| if (foundAnnotation != null) { | ||
| return foundAnnotation; | ||
| } | ||
| } | ||
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| return null; | ||
| } | ||
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| @VisibleForTesting | ||
| static Set<Class<?>> getParentClasses(Class<?> clazz) { | ||
| ImmutableSet.Builder<Class<?>> builder = ImmutableSet.builder(); | ||
| builder.add(clazz.getInterfaces()); | ||
| Class<?> superclass = clazz.getSuperclass(); | ||
| while (superclass != null) { | ||
| builder.add(superclass.getInterfaces()); | ||
| builder.add(superclass); | ||
| superclass = superclass.getSuperclass(); | ||
| } | ||
| return builder.build(); | ||
| } | ||
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| public static final class MethodSignature { | ||
| private final String methodName; | ||
| private final Class<?>[] parameterTypes; | ||
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| private static final Class<?>[] NO_ARGS = new Class<?>[0]; | ||
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| private MethodSignature(String methodName, Class<?>... parameterTypes) { | ||
| this.methodName = checkNotNull(methodName); | ||
| this.parameterTypes = (parameterTypes == null || parameterTypes.length == 0) | ||
| ? NO_ARGS : parameterTypes.clone(); | ||
| } | ||
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| public String getMethodName() { | ||
| return methodName; | ||
| } | ||
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| public Class<?>[] getParameterTypes() { | ||
| return parameterTypes; | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| return "MethodSignature{" | ||
| + "methodName='" + methodName + '\'' | ||
| + ", parameterTypes=" + Arrays.toString(parameterTypes) | ||
| + '}'; | ||
| } | ||
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| @Override | ||
| public boolean equals(Object other) { | ||
| if (this == other) { | ||
| return true; | ||
| } | ||
| if (other == null || getClass() != other.getClass()) { | ||
| return false; | ||
| } | ||
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| MethodSignature that = (MethodSignature) other; | ||
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| if (getMethodName() != null ? !getMethodName().equals(that.getMethodName()) | ||
| : that.getMethodName() != null) { | ||
| return false; | ||
| } | ||
| // Probably incorrect - comparing Object[] arrays with Arrays.equals | ||
| return Arrays.equals(getParameterTypes(), that.getParameterTypes()); | ||
| } | ||
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| @Override | ||
| public int hashCode() { | ||
| int result = getMethodName() != null ? getMethodName().hashCode() : 0; | ||
| result = 31 * result + Arrays.hashCode(getParameterTypes()); | ||
| return result; | ||
| } | ||
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| public static MethodSignature of(Method method) { | ||
| return MethodSignature.of(method.getName(), method.getParameterTypes()); | ||
| } | ||
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| public static MethodSignature of(String methodName, Class<?>... parameterTypes) { | ||
| return new MethodSignature(methodName, parameterTypes); | ||
| } | ||
| } | ||
| } |
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