Java tutorial
/* * Copyright 2016 The Netty Project * * The Netty Project 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 io.netty.util; import io.netty.util.internal.ObjectUtil; import io.netty.util.internal.PlatformDependent; import io.netty.util.internal.SystemPropertyUtil; import io.netty.util.internal.logging.InternalLogger; import io.netty.util.internal.logging.InternalLoggerFactory; import java.lang.reflect.Constructor; /** * This static factory should be used to load {@link ResourceLeakDetector}s as needed */ public abstract class ResourceLeakDetectorFactory { private static final InternalLogger logger = InternalLoggerFactory .getInstance(ResourceLeakDetectorFactory.class); private static volatile ResourceLeakDetectorFactory factoryInstance = new DefaultResourceLeakDetectorFactory(); /** * Get the singleton instance of this factory class. * * @return the current {@link ResourceLeakDetectorFactory} */ public static ResourceLeakDetectorFactory instance() { return factoryInstance; } /** * Set the factory's singleton instance. This has to be called before the static initializer of the * {@link ResourceLeakDetector} is called by all the callers of this factory. That is, before initializing a * Netty Bootstrap. * * @param factory the instance that will become the current {@link ResourceLeakDetectorFactory}'s singleton */ public static void setResourceLeakDetectorFactory(ResourceLeakDetectorFactory factory) { factoryInstance = ObjectUtil.checkNotNull(factory, "factory"); } /** * Returns a new instance of a {@link ResourceLeakDetector} with the given resource class. * * @param resource the resource class used to initialize the {@link ResourceLeakDetector} * @param <T> the type of the resource class * @return a new instance of {@link ResourceLeakDetector} */ public final <T> ResourceLeakDetector<T> newResourceLeakDetector(Class<T> resource) { return newResourceLeakDetector(resource, ResourceLeakDetector.SAMPLING_INTERVAL); } /** * @deprecated Use {@link #newResourceLeakDetector(Class, int)} instead. * <p> * Returns a new instance of a {@link ResourceLeakDetector} with the given resource class. * * @param resource the resource class used to initialize the {@link ResourceLeakDetector} * @param samplingInterval the interval on which sampling takes place * @param maxActive This is deprecated and will be ignored. * @param <T> the type of the resource class * @return a new instance of {@link ResourceLeakDetector} */ @Deprecated public abstract <T> ResourceLeakDetector<T> newResourceLeakDetector(Class<T> resource, int samplingInterval, long maxActive); /** * Returns a new instance of a {@link ResourceLeakDetector} with the given resource class. * * @param resource the resource class used to initialize the {@link ResourceLeakDetector} * @param samplingInterval the interval on which sampling takes place * @param <T> the type of the resource class * @return a new instance of {@link ResourceLeakDetector} */ @SuppressWarnings("deprecation") public <T> ResourceLeakDetector<T> newResourceLeakDetector(Class<T> resource, int samplingInterval) { return newResourceLeakDetector(resource, ResourceLeakDetector.SAMPLING_INTERVAL, Long.MAX_VALUE); } /** * Default implementation that loads custom leak detector via system property */ private static final class DefaultResourceLeakDetectorFactory extends ResourceLeakDetectorFactory { private final Constructor<?> obsoleteCustomClassConstructor; private final Constructor<?> customClassConstructor; DefaultResourceLeakDetectorFactory() { String customLeakDetector; try { customLeakDetector = SystemPropertyUtil.get("io.netty.customResourceLeakDetector"); } catch (Throwable cause) { logger.error("Could not access System property: io.netty.customResourceLeakDetector", cause); customLeakDetector = null; } if (customLeakDetector == null) { obsoleteCustomClassConstructor = customClassConstructor = null; } else { obsoleteCustomClassConstructor = obsoleteCustomClassConstructor(customLeakDetector); customClassConstructor = customClassConstructor(customLeakDetector); } } private static Constructor<?> obsoleteCustomClassConstructor(String customLeakDetector) { try { final Class<?> detectorClass = Class.forName(customLeakDetector, true, PlatformDependent.getSystemClassLoader()); if (ResourceLeakDetector.class.isAssignableFrom(detectorClass)) { return detectorClass.getConstructor(Class.class, int.class, long.class); } else { logger.error("Class {} does not inherit from ResourceLeakDetector.", customLeakDetector); } } catch (Throwable t) { logger.error("Could not load custom resource leak detector class provided: {}", customLeakDetector, t); } return null; } private static Constructor<?> customClassConstructor(String customLeakDetector) { try { final Class<?> detectorClass = Class.forName(customLeakDetector, true, PlatformDependent.getSystemClassLoader()); if (ResourceLeakDetector.class.isAssignableFrom(detectorClass)) { return detectorClass.getConstructor(Class.class, int.class); } else { logger.error("Class {} does not inherit from ResourceLeakDetector.", customLeakDetector); } } catch (Throwable t) { logger.error("Could not load custom resource leak detector class provided: {}", customLeakDetector, t); } return null; } @SuppressWarnings("deprecation") @Override public <T> ResourceLeakDetector<T> newResourceLeakDetector(Class<T> resource, int samplingInterval, long maxActive) { if (obsoleteCustomClassConstructor != null) { try { @SuppressWarnings("unchecked") ResourceLeakDetector<T> leakDetector = (ResourceLeakDetector<T>) obsoleteCustomClassConstructor .newInstance(resource, samplingInterval, maxActive); logger.debug("Loaded custom ResourceLeakDetector: {}", obsoleteCustomClassConstructor.getDeclaringClass().getName()); return leakDetector; } catch (Throwable t) { logger.error( "Could not load custom resource leak detector provided: {} with the given resource: {}", obsoleteCustomClassConstructor.getDeclaringClass().getName(), resource, t); } } ResourceLeakDetector<T> resourceLeakDetector = new ResourceLeakDetector<T>(resource, samplingInterval, maxActive); logger.debug("Loaded default ResourceLeakDetector: {}", resourceLeakDetector); return resourceLeakDetector; } @Override public <T> ResourceLeakDetector<T> newResourceLeakDetector(Class<T> resource, int samplingInterval) { if (customClassConstructor != null) { try { @SuppressWarnings("unchecked") ResourceLeakDetector<T> leakDetector = (ResourceLeakDetector<T>) customClassConstructor .newInstance(resource, samplingInterval); logger.debug("Loaded custom ResourceLeakDetector: {}", customClassConstructor.getDeclaringClass().getName()); return leakDetector; } catch (Throwable t) { logger.error( "Could not load custom resource leak detector provided: {} with the given resource: {}", customClassConstructor.getDeclaringClass().getName(), resource, t); } } ResourceLeakDetector<T> resourceLeakDetector = new ResourceLeakDetector<T>(resource, samplingInterval); logger.debug("Loaded default ResourceLeakDetector: {}", resourceLeakDetector); return resourceLeakDetector; } } }