Java tutorial
/* * 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.flink.runtime.state; import org.apache.flink.core.fs.FSDataInputStream; import java.io.IOException; import java.io.InputStream; /** * Wrapper around a FSDataInputStream to limit the maximum read offset. * * Based on the implementation from org.apache.commons.io.input.BoundedInputStream */ public class BoundedInputStream extends InputStream { private final FSDataInputStream delegate; private long endOffsetExclusive; private long position; private long mark; public BoundedInputStream(FSDataInputStream delegate, long endOffsetExclusive) throws IOException { this.position = delegate.getPos(); this.mark = -1L; this.endOffsetExclusive = endOffsetExclusive; this.delegate = delegate; } public int read() throws IOException { if (endOffsetExclusive >= 0L && position >= endOffsetExclusive) { return -1; } else { int result = delegate.read(); ++position; return result; } } public int read(byte[] b) throws IOException { return read(b, 0, b.length); } public int read(byte[] b, int off, int len) throws IOException { if (endOffsetExclusive >= 0L && position >= endOffsetExclusive) { return -1; } else { long maxRead = endOffsetExclusive >= 0L ? Math.min((long) len, endOffsetExclusive - position) : (long) len; int bytesRead = delegate.read(b, off, (int) maxRead); if (bytesRead == -1) { return -1; } else { position += (long) bytesRead; return bytesRead; } } } public long skip(long n) throws IOException { long toSkip = endOffsetExclusive >= 0L ? Math.min(n, endOffsetExclusive - position) : n; long skippedBytes = delegate.skip(toSkip); position += skippedBytes; return skippedBytes; } public int available() throws IOException { return endOffsetExclusive >= 0L && position >= endOffsetExclusive ? 0 : delegate.available(); } public String toString() { return delegate.toString(); } public void close() throws IOException { delegate.close(); } public synchronized void reset() throws IOException { delegate.reset(); position = mark; } public synchronized void mark(int readlimit) { delegate.mark(readlimit); mark = position; } public long getEndOffsetExclusive() { return endOffsetExclusive; } public void setEndOffsetExclusive(long endOffsetExclusive) { this.endOffsetExclusive = endOffsetExclusive; } public boolean markSupported() { return delegate.markSupported(); } }