hadoop AvroFSInput 源码
haddop AvroFSInput 代码
文件路径：/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/AvroFSInput.java
/**
* 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;
import java.io.Closeable;
import java.io.IOException;
import org.apache.avro.file.SeekableInput;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY;
import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY_SEQUENTIAL;
import static org.apache.hadoop.util.functional.FutureIO.awaitFuture;
/** Adapts an {@link FSDataInputStream} to Avro's SeekableInput interface. */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class AvroFSInput implements Closeable, SeekableInput {
private final FSDataInputStream stream;
private final long len;
/**
* Construct given an {@link FSDataInputStream} and its length.
*
* @param in inputstream.
* @param len len.
*/
public AvroFSInput(final FSDataInputStream in, final long len) {
this.stream = in;
this.len = len;
}
/** Construct given a {@link FileContext} and a {@link Path}.
* @param fc filecontext.
* @param p the path.
* @throws IOException If an I/O error occurred.
* */
public AvroFSInput(final FileContext fc, final Path p) throws IOException {
FileStatus status = fc.getFileStatus(p);
this.len = status.getLen();
this.stream = awaitFuture(fc.openFile(p)
.opt(FS_OPTION_OPENFILE_READ_POLICY,
FS_OPTION_OPENFILE_READ_POLICY_SEQUENTIAL)
.withFileStatus(status)
.build());
fc.open(p);
}
@Override
public long length() {
return len;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
return stream.read(b, off, len);
}
@Override
public void seek(long p) throws IOException {
stream.seek(p);
}
@Override
public long tell() throws IOException {
return stream.getPos();
}
@Override
public void close() throws IOException {
stream.close();
}
}
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