mirror of
https://github.com/chrislusf/seaweedfs
synced 2024-05-26 13:20:57 +02:00
75 lines
2.2 KiB
Java
75 lines
2.2 KiB
Java
/*
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* Copyright 2014 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package seaweedfs.client.btree;
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import com.google.common.io.CountingInputStream;
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import java.io.BufferedInputStream;
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import java.io.DataInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.RandomAccessFile;
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/**
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* Allows a stream of bytes to be read from a particular location of some backing byte stream.
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*/
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class ByteInput {
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private final RandomAccessFile file;
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private final ResettableBufferedInputStream bufferedInputStream;
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private CountingInputStream countingInputStream;
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public ByteInput(RandomAccessFile file) {
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this.file = file;
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bufferedInputStream = new ResettableBufferedInputStream(new RandomAccessFileInputStream(file));
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}
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/**
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* Starts reading from the given offset.
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*/
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public DataInputStream start(long offset) throws IOException {
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file.seek(offset);
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bufferedInputStream.clear();
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countingInputStream = new CountingInputStream(bufferedInputStream);
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return new DataInputStream(countingInputStream);
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}
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/**
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* Returns the number of bytes read since {@link #start(long)} was called.
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*/
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public long getBytesRead() {
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return countingInputStream.getCount();
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}
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/**
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* Finishes reading, resetting any buffered state.
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*/
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public void done() {
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countingInputStream = null;
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}
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private static class ResettableBufferedInputStream extends BufferedInputStream {
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ResettableBufferedInputStream(InputStream input) {
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super(input);
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}
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void clear() {
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count = 0;
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pos = 0;
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}
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}
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}
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