com.facebook.hive.orc.StripeReader.java Source code

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Here is the source code for com.facebook.hive.orc.StripeReader.java

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//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.

/**
 * 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 com.facebook.hive.orc;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import com.facebook.hive.orc.OrcFile.KeyWrapper;
import com.facebook.hive.orc.OrcFile.ValueWrapper;

public class StripeReader {
    private final FSDataInputStream file;
    private final List<StripeInformation> stripes = new ArrayList<StripeInformation>();
    private StripeInformation currentStripe;
    private byte[] currentData;
    private int stripesRead = 0;

    StripeReader(Iterable<StripeInformation> stripes, FileSystem fileSystem, Path path, long offset, long length)
            throws IOException {
        this.file = fileSystem.open(path);
        for (StripeInformation stripe : stripes) {
            long stripeStart = stripe.getOffset();
            if (stripeStart >= offset && stripeStart < offset + length) {
                this.stripes.add(stripe);
            }
        }
    }

    private void readStripe() throws IOException {
        currentStripe = stripes.get(stripesRead);
        currentData = new byte[(int) (currentStripe.getIndexLength() + currentStripe.getDataLength()
                + currentStripe.getFooterLength())];
        file.seek(currentStripe.getOffset());
        file.readFully(currentData, 0, currentData.length);
    }

    public boolean hasNext() throws IOException {
        return stripesRead < stripes.size();
    }

    public boolean nextStripe(KeyWrapper keyWrapper, ValueWrapper valueWrapper) throws IOException {
        if (hasNext()) {
            readStripe();
            keyWrapper.key = currentStripe;
            valueWrapper.value = currentData;
            stripesRead += 1;
        }
        return hasNext();
    }

    public void close() throws IOException {
        file.close();
    }

    public long getPosition() throws IOException {
        return file.getPos();
    }

    /**
     * Return the fraction of stripes that have been read from the selected.
     * section of the file
     * @return fraction between 0.0 and 1.0 of stripes consumed
     */
    public float getProgress() {
        return ((float) stripesRead) / stripes.size();
    }
}