com.forerunnergames.tools.common.pool.AutoDisposable.java Source code

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Here is the source code for com.forerunnergames.tools.common.pool.AutoDisposable.java

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/*
 * Copyright  2013 - 2016 Forerunner Games, LLC
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.forerunnergames.tools.common.pool;

import com.forerunnergames.tools.common.Arguments;

import com.google.common.base.Optional;

import java.io.Closeable;
import java.io.IOException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * An automated delegate type for wrapping non-Disposable types. A DisposableCallback can be provided to be to which the
 * AutoDisposable will delegate a call to {@link #dispose()}.
 *
 * @see DisposableCallback
 */
public class AutoDisposable<T> implements Disposable {
    private static final Logger log = LoggerFactory.getLogger(AutoDisposable.class);
    private final T objRef;
    private final DisposableCallback<T> disposableCallback;

    @Override
    public void dispose() throws Exception {
        disposableCallback.dispose(objRef);
    }

    @Override
    public int hashCode() {
        return objRef.hashCode();
    }

    @Override
    public boolean equals(final Object obj) {
        Arguments.checkIsNotNull(obj, "obj");

        return obj instanceof AutoDisposable && objRef.equals(((AutoDisposable<?>) obj).unpack());
    }

    /**
     * Creates an AutoDisposable with the given object instance and an empty callback task.
     */
    public static <T> AutoDisposable<T> forObject(final T objRef) {
        Arguments.checkIsNotNull(objRef, "objRef");

        return new AutoDisposable<>(objRef, new DisposableCallback<T>() {
            @Override
            public void dispose(final T objRef) {
                Arguments.checkIsNotNull(objRef, "objRef");

            }
        });
    }

    /**
     * Wraps the given object factory with an AutoDisposable factory.
     */
    public static <T> PoolFactory<AutoDisposable<T>> forObject(final PoolFactory<T> factory) {
        Arguments.checkIsNotNull(factory, "factory");

        return new PoolFactory<AutoDisposable<T>>() {
            @Override
            public AutoDisposable<T> make() {
                return forObject(factory.make());
            }
        };
    }

    public static <T extends Closeable> AutoDisposable<T> forCloseable(final T objRef) {
        Arguments.checkIsNotNull(objRef, "objRef");

        return new AutoDisposable<>(objRef, new DisposableCallback<T>() {
            @Override
            public void dispose(final T objRef) {
                Arguments.checkIsNotNull(objRef, "objRef");

                try {
                    objRef.close();
                } catch (final IOException e) {
                    log.error("Caught error from closeable: ", e);
                }
            }
        });
    }

    public static <T extends Closeable> PoolFactory<AutoDisposable<T>> forCloseable(final PoolFactory<T> factory) {
        Arguments.checkIsNotNull(factory, "factory");

        return new PoolFactory<AutoDisposable<T>>() {
            @Override
            public AutoDisposable<T> make() {
                return forCloseable(factory.make());
            }
        };
    }

    /**
     * @param objRef
     *          the object instance to wrap
     * @param disposableCallback
     *          the callback task to invoke when {@link #dispose()} is called on AutoDisposable.
     */
    public static <T> AutoDisposable<T> forObjectWith(final T objRef,
            final DisposableCallback<T> disposableCallback) {
        Arguments.checkIsNotNull(objRef, "objRef");
        Arguments.checkIsNotNull(disposableCallback, "disposableCallback");

        return new AutoDisposable<>(objRef, disposableCallback);
    }

    public static <T> PoolFactory<AutoDisposable<T>> forObjectWith(final PoolFactory<T> factory,
            final DisposableCallback<T> disposableCallback) {
        Arguments.checkIsNotNull(factory, "factory");
        Arguments.checkIsNotNull(disposableCallback, "disposableCallback");

        return new PoolFactory<AutoDisposable<T>>() {
            @Override
            public AutoDisposable<T> make() {
                return forObjectWith(factory.make(), disposableCallback);
            }
        };
    }

    /**
     * Acquires an AutoDisposable from the given pool and unpacks the reference, returning it as an Optional of the
     * AutoDisposable's parameterized type.
     */
    public static <T> Optional<T> acquireFrom(final ObjectPool<AutoDisposable<T>> pool) {
        Arguments.checkIsNotNull(pool, "pool");

        final Optional<AutoDisposable<T>> ref = pool.acquire();
        if (ref.isPresent())
            return Optional.of(ref.get().unpack());
        return Optional.absent();
    }

    /**
     * @return the object reference; guaranteed to be non-null.
     */
    public T unpack() {
        return objRef;
    }

    private AutoDisposable(final T objRef, final DisposableCallback<T> disposableCallback) {
        this.objRef = objRef;
        this.disposableCallback = disposableCallback;
    }

    public interface DisposableCallback<R> {
        void dispose(final R objRef);
    }
}