gradle-master/subprojects/persistent-cache/src/main/java/org/gradle/cache/internal/FileIntegrityViolationSuppressingObjectHolderDecorator.java
/*
 * Copyright 2012 the original author or authors.
 *
 * 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.
 */

package org.gradle.cache.internal;

import org.gradle.cache.FileIntegrityViolationException;
import org.gradle.cache.ObjectHolder;
import org.gradle.internal.Factory;

public class FileIntegrityViolationSuppressingObjectHolderDecorator<T> implements ObjectHolder<T> {

    private final ObjectHolder<T> delegate;

    public FileIntegrityViolationSuppressingObjectHolderDecorator(ObjectHolder<T> delegate) {
        this.delegate = delegate;
    }

    @Override
    public T get() {
        try {
            return delegate.get();
        } catch (FileIntegrityViolationException e) {
            return null;
        }
    }

    @Override
    public void set(T newValue) {
        delegate.set(newValue);
    }

    @Override
    public T update(final UpdateAction<T> updateAction) {
        return doUpdate(updateAction, new Factory<T>() {
            @Override
            public T create() {
                return delegate.update(updateAction);
            }
        });
    }

    @Override
    public T maybeUpdate(final UpdateAction<T> updateAction) {
        return doUpdate(updateAction, new Factory<T>() {
            @Override
            public T create() {
                return delegate.maybeUpdate(updateAction);
            }
        });
    }

    private T doUpdate(UpdateAction<T> updateAction, Factory<T> work) {
        try {
            return work.create();
        } catch (FileIntegrityViolationException e) {
            T newValue = updateAction.update(null);
            set(newValue);
            return newValue;
        }
    }
}
