org.apache.lucene.store.IndexOutput.java Source code

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Here is the source code for org.apache.lucene.store.IndexOutput.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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 org.apache.lucene.store;

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

/**
 * A {@link DataOutput} for appending data to a file in a {@link Directory}.
 *
 * Instances of this class are <b>not</b> thread-safe.
 *
 * @see Directory
 * @see IndexInput
 */
public abstract class IndexOutput extends DataOutput implements Closeable {

    /** Full description of this output, e.g. which class such as {@code FSIndexOutput}, and the full path to the file */
    private final String resourceDescription;

    /** Just the name part from {@code resourceDescription} */
    private final String name;

    /** Sole constructor.  resourceDescription should be non-null, opaque string
     *  describing this resource; it's returned from {@link #toString}. */
    protected IndexOutput(String resourceDescription, String name) {
        if (resourceDescription == null) {
            throw new IllegalArgumentException("resourceDescription must not be null");
        }
        this.resourceDescription = resourceDescription;
        this.name = name;
    }

    /** Returns the name used to create this {@code IndexOutput}.  This is especially useful when using
     * {@link Directory#createTempOutput}. */
    // TODO: can we somehow use this as the default resource description or something?
    public String getName() {
        return name;
    }

    /** Closes this stream to further operations. */
    @Override
    public abstract void close() throws IOException;

    /** Returns the current position in this file, where the next write will
     * occur.
     */
    public abstract long getFilePointer();

    /** Returns the current checksum of bytes written so far */
    public abstract long getChecksum() throws IOException;

    @Override
    public String toString() {
        return resourceDescription;
    }
}