org.apache.hadoop.fs.s3.S3InputStream.java Source code

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Here is the source code for org.apache.hadoop.fs.s3.S3InputStream.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.hadoop.fs.s3;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.EOFException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSInputStream;
import org.apache.hadoop.fs.FileSystem;

@InterfaceAudience.Private
@InterfaceStability.Unstable
@Deprecated
class S3InputStream extends FSInputStream {

    private FileSystemStore store;

    private Block[] blocks;

    private boolean closed;

    private long fileLength;

    private long pos = 0;

    private File blockFile;

    private DataInputStream blockStream;

    private long blockEnd = -1;

    private FileSystem.Statistics stats;

    private static final Log LOG = LogFactory.getLog(S3InputStream.class.getName());

    @Deprecated
    public S3InputStream(Configuration conf, FileSystemStore store, INode inode) {
        this(conf, store, inode, null);
    }

    public S3InputStream(Configuration conf, FileSystemStore store, INode inode, FileSystem.Statistics stats) {

        this.store = store;
        this.stats = stats;
        this.blocks = inode.getBlocks();
        for (Block block : blocks) {
            this.fileLength += block.getLength();
        }
    }

    @Override
    public synchronized long getPos() throws IOException {
        return pos;
    }

    @Override
    public synchronized int available() throws IOException {
        return (int) (fileLength - pos);
    }

    @Override
    public synchronized void seek(long targetPos) throws IOException {
        String message = String.format("Cannot seek to %d", targetPos);
        if (targetPos > fileLength) {
            throw new EOFException(message + ": after EOF");
        }
        if (targetPos < 0) {
            throw new EOFException(message + ": negative");
        }
        pos = targetPos;
        blockEnd = -1;
    }

    @Override
    public synchronized boolean seekToNewSource(long targetPos) throws IOException {
        return false;
    }

    @Override
    public synchronized int read() throws IOException {
        if (closed) {
            throw new IOException("Stream closed");
        }
        int result = -1;
        if (pos < fileLength) {
            if (pos > blockEnd) {
                blockSeekTo(pos);
            }
            result = blockStream.read();
            if (result >= 0) {
                pos++;
            }
        }
        if (stats != null && result >= 0) {
            stats.incrementBytesRead(1);
        }
        return result;
    }

    @Override
    public synchronized int read(byte buf[], int off, int len) throws IOException {
        if (closed) {
            throw new IOException("Stream closed");
        }
        if (pos < fileLength) {
            if (pos > blockEnd) {
                blockSeekTo(pos);
            }
            int realLen = (int) Math.min((long) len, (blockEnd - pos + 1L));
            int result = blockStream.read(buf, off, realLen);
            if (result >= 0) {
                pos += result;
            }
            if (stats != null && result > 0) {
                stats.incrementBytesRead(result);
            }
            return result;
        }
        return -1;
    }

    private synchronized void blockSeekTo(long target) throws IOException {
        //
        // Compute desired block
        //
        int targetBlock = -1;
        long targetBlockStart = 0;
        long targetBlockEnd = 0;
        for (int i = 0; i < blocks.length; i++) {
            long blockLength = blocks[i].getLength();
            targetBlockEnd = targetBlockStart + blockLength - 1;

            if (target >= targetBlockStart && target <= targetBlockEnd) {
                targetBlock = i;
                break;
            } else {
                targetBlockStart = targetBlockEnd + 1;
            }
        }
        if (targetBlock < 0) {
            throw new IOException("Impossible situation: could not find target position " + target);
        }
        long offsetIntoBlock = target - targetBlockStart;

        // read block blocks[targetBlock] from position offsetIntoBlock

        this.blockFile = store.retrieveBlock(blocks[targetBlock], offsetIntoBlock);

        this.pos = target;
        this.blockEnd = targetBlockEnd;
        this.blockStream = new DataInputStream(new FileInputStream(blockFile));

    }

    @Override
    public void close() throws IOException {
        if (closed) {
            return;
        }
        if (blockStream != null) {
            blockStream.close();
            blockStream = null;
        }
        if (blockFile != null) {
            boolean b = blockFile.delete();
            if (!b) {
                LOG.warn("Ignoring failed delete");
            }
        }
        super.close();
        closed = true;
    }

    /**
     * We don't support marks.
     */
    @Override
    public boolean markSupported() {
        return false;
    }

    @Override
    public void mark(int readLimit) {
        // Do nothing
    }

    @Override
    public void reset() throws IOException {
        throw new IOException("Mark not supported");
    }

}