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/*
 * Copyright 2022 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:
 *
 *   https://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.netty5.util.internal;

import io.netty5.util.ReferenceCounted;
import io.netty5.util.Resource;
import io.netty5.util.internal.logging.InternalLogger;

/**
 * Utility class for disposing of {@linkplain Resource resources} without propagating any exception that
 * {@link Resource#close()} might throw.
 */
public final class SilentDispose {
    /**
     * Attempt to dispose of whatever the given object is.
     * 
     * This method works similarly to {@link Resource#dispose(Object)}, except any exception thrown will be logged
     * instead of propagated.
     * 

     * If the object is {@link AutoCloseable}, such as anything that implements {@link Resource},
     * then it will be closed.
     * If the object is {@link ReferenceCounted}, then it will be released once.
     * 

     * Any exceptions caused by this will be logged using the given logger.
     * The exception will be logged at log-level {@link io.netty5.util.internal.logging.InternalLogLevel#WARN WARN}.
     *
     * @param obj The object to dispose of.
     * @param logger The logger to use for recording any exceptions thrown by the disposal.
     */
    public static void dispose(Object obj, InternalLogger logger) {
        try {
            Resource.dispose(obj);
        } catch (Throwable throwable) {
            logger.warn("Failed to dispose object: {}.", obj, throwable);
        }
    }

    /**
     * Attempt to dispose of whatever the given object is, but only if it is disposable.
     * 

     * This method works similarly to {@link #dispose(Object, InternalLogger)}, except the object is only disposed of
     * if it is {@linkplain Resource#isAccessible(Object, boolean) accessible}.
     * 

     * Any exceptions caused by the disposal of the object will be logged using the given logger.
     * The exception will be logged at log-level {@link io.netty5.util.internal.logging.InternalLogLevel#WARN WARN}.
     *
     * @param obj The object to dispose of.
     * @param logger The logger to use for recording any exceptions thrown by the disposal.
     */
    public static void trySilentDispose(Object obj, InternalLogger logger) {
        if (Resource.isAccessible(obj, false)) {
            dispose(obj, logger);
        }
    }

    /**
     * Attempt to dispose of whatever the given object is, but only if it is disposable.
     * 

     * This method works similarly to {@link Resource#dispose(Object)}, except the object is only disposed of if it is
     * {@linkplain Resource#isAccessible(Object, boolean) accessible}.
     * 

     * Any exceptions caused the disposal will be allowed to propagate from this method, which is in contrast to how
     * {@link #dispose(Object, InternalLogger)} and {@link #trySilentDispose(Object, InternalLogger)} works.
     *
     * @param obj The object to dispose of.
     */
    public static void tryPropagatingDispose(Object obj) {
        if (Resource.isAccessible(obj, false)) {
            Resource.dispose(obj);
        }
    }

    /**
     * Return an {@link AutoCloseable} for the given object, which can be used to dispose of it using a
     * try-with-resources clause.
     * 

     * The benefit of this approach is that exceptions are correctly handled if both the try-body, and the resource
     * disposal, throws.
     * 
     * This is not a silent operation, in that exceptions from resource disposal will propagate.
     * However, the try-with-resources clause will guarantee that resource disposal exceptions won't shadow any
     * exceptions from the try-body
     *
     * @param obj The object to dispose of.
     * @return An {@link AutoCloseable} that will dispose of the given object when closed.
     */
    public static AutoCloseable autoClosing(Object obj) {
        if (obj instanceof AutoCloseable) {
            return (AutoCloseable) obj;
        }
        if (obj instanceof ReferenceCounted) {
            return () -> ((ReferenceCounted) obj).release();
        }
        // It is safe to use null in try-with-resources. We can use that for uncloseable/unreleasable things.
        return null;
    }

    private SilentDispose() {
    }
}