com.mycila.hc.io.DelegatingContentProvider.groovy Maven / Gradle / Ivy

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/**
 * Copyright (C) 2013 Mycila ([email protected])
 *
 * 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 com.mycila.hc.io

import java.nio.ByteBuffer

/**
 * @author Mathieu Carbou ([email protected])
 * @date 2014-02-17
 */
class DelegatingContentProvider implements ContentProvider {

    protected final ContentProviderFactory factory
    protected volatile ContentProvider _contentProvider

    DelegatingContentProvider(ContentProviderFactory factory) {
        this.factory = factory
    }

    @Override
    void close() throws IOException {
        _contentProvider?.close()
        _contentProvider = null
    }

    @Override
    long getLength() {
        contentProvider.length
    }

    @Override
    Iterator iterator() {
        contentProvider.iterator()
    }

    protected ContentProvider getContentProvider() {
        if (_contentProvider == null) {
            synchronized (factory) {
                if (_contentProvider == null) {
                    _contentProvider = factory.create()
                }
            }
        }
        return _contentProvider
    }

}