Java tutorial
/** * 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 org.apache.drill.common.scanner.persistence; import static com.google.common.base.Preconditions.checkNotNull; import static java.lang.String.format; import static java.util.Arrays.asList; import static java.util.Collections.unmodifiableList; import static java.util.Collections.unmodifiableSet; import static java.util.concurrent.TimeUnit.MILLISECONDS; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import org.apache.drill.common.exceptions.DrillRuntimeException; import com.fasterxml.jackson.annotation.JsonCreator; import com.fasterxml.jackson.annotation.JsonProperty; import com.google.common.base.Stopwatch; import com.google.common.collect.HashMultimap; import com.google.common.collect.Multimap; /** * The root doc of the scan result */ public final class ScanResult { private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ScanResult.class); private final List<String> scannedPackages; private final Set<String> scannedClasses; private final Set<String> scannedAnnotations; private final List<AnnotatedClassDescriptor> annotatedClasses; private final List<ParentClassDescriptor> implementations; private final Map<String, ParentClassDescriptor> parentClassByName; private final Multimap<String, AnnotatedClassDescriptor> annotationsByName; @JsonCreator public ScanResult(@JsonProperty("scannedPackages") Collection<String> scannedPackages, @JsonProperty("scannedClasses") Collection<String> scannedClasses, @JsonProperty("scannedAnnotations") Collection<String> scannedAnnotations, @JsonProperty("annotatedClasses") Collection<AnnotatedClassDescriptor> annotatedClasses, @JsonProperty("implementations") Collection<ParentClassDescriptor> implementations) { this.scannedPackages = unmodifiableList(new ArrayList<>(checkNotNull(scannedPackages))); this.scannedClasses = unmodifiableSet(new HashSet<>(checkNotNull(scannedClasses))); this.scannedAnnotations = unmodifiableSet(new HashSet<>(checkNotNull(scannedAnnotations))); this.annotatedClasses = unmodifiableList(new ArrayList<>(checkNotNull(annotatedClasses))); this.implementations = unmodifiableList(new ArrayList<>(checkNotNull(implementations))); this.parentClassByName = new HashMap<>(); for (ParentClassDescriptor parentClassDescriptor : implementations) { this.parentClassByName.put(parentClassDescriptor.getName(), parentClassDescriptor); } this.annotationsByName = HashMultimap.create(); for (AnnotatedClassDescriptor annotated : annotatedClasses) { for (AnnotationDescriptor annotationDescriptor : annotated.getAnnotations()) { if (scannedAnnotations.contains(annotationDescriptor.getAnnotationType())) { this.annotationsByName.put(annotationDescriptor.getAnnotationType(), annotated); } } } } /** * @return packages that were scanned as defined in the drill configs */ public List<String> getScannedPackages() { return scannedPackages; } /** * @return functions annotated with configured annotations */ public List<AnnotatedClassDescriptor> getAnnotatedClasses() { return annotatedClasses; } /** * @return list of implementations per parent class */ public List<ParentClassDescriptor> getImplementations() { return implementations; } public Set<String> getScannedClasses() { return scannedClasses; } public Set<String> getScannedAnnotations() { return scannedAnnotations; } /** * @param c the parent class name * @return the descriptor for the implementations found */ public ParentClassDescriptor getImplementations(String c) { if (!scannedClasses.contains(c)) { throw new IllegalArgumentException(c + " is not scanned. " + "Only implementations for the following classes are scanned: " + scannedClasses); } return parentClassByName.get(c); } /** * This will load all the scanned classes for this parent as a side effect * @param c the parent * @return all the classes found */ public <T> Set<Class<? extends T>> getImplementations(Class<T> c) { ParentClassDescriptor p = getImplementations(c.getName()); Stopwatch watch = Stopwatch.createStarted(); Set<Class<? extends T>> result = new HashSet<>(); try { if (p != null) { for (ChildClassDescriptor child : p.getChildren()) { if (!child.isAbstract()) { try { result.add(Class.forName(child.getName()).asSubclass(c)); } catch (ClassNotFoundException e) { throw new DrillRuntimeException("scanned class could not be found: " + child.getName(), e); } } } } return result; } finally { logger.info(format("loading %d classes for %s took %dms", result.size(), c.getName(), watch.elapsed(MILLISECONDS))); } } /** * @param c the annotation class name * @return the descriptor of the annotated class */ public List<AnnotatedClassDescriptor> getAnnotatedClasses(String c) { if (!scannedAnnotations.contains(c)) { throw new IllegalArgumentException( c + " is not scanned. " + "Only the following Annotations are scanned: " + scannedAnnotations); } return new ArrayList<>(annotationsByName.get(c)); } @Override public String toString() { return "ScanResult [" + "scannedPackages=" + scannedPackages + ", " + "scannedClasses=" + scannedClasses + ", " + "scannedAnnotations=" + scannedAnnotations + ", " + "annotatedClasses=" + annotatedClasses + ", " + "implementations=" + implementations + "]"; } private <T> List<T> merge(Collection<T> a, Collection<T> b) { final List<T> newList = new ArrayList<>(a); newList.addAll(b); return newList; } /** * merges this and other together into a new result object * @param other * @return the resulting merge */ public ScanResult merge(ScanResult other) { final Multimap<String, ChildClassDescriptor> newImpls = HashMultimap.create(); for (Collection<ParentClassDescriptor> impls : asList(implementations, other.implementations)) { for (ParentClassDescriptor c : impls) { newImpls.putAll(c.getName(), c.getChildren()); } } List<ParentClassDescriptor> newImplementations = new ArrayList<>(); for (Entry<String, Collection<ChildClassDescriptor>> entry : newImpls.asMap().entrySet()) { newImplementations.add(new ParentClassDescriptor(entry.getKey(), new ArrayList<>(entry.getValue()))); } return new ScanResult(merge(scannedPackages, other.scannedPackages), merge(scannedClasses, other.scannedClasses), merge(scannedAnnotations, other.scannedAnnotations), merge(annotatedClasses, other.annotatedClasses), newImplementations); } }