/**
* 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.IOException;
import java.nio.ByteBuffer;
/**
* Implementers of this interface provide a read API that writes to a
* ByteBuffer, not a byte[].
*/
public interface ByteBufferReadable {
/**
* Reads up to buf.remaining() bytes into buf. Callers should use
* buf.limit(..) to control the size of the desired read.
* <p/>
* After a successful call, buf.position() and buf.limit() should be
* unchanged, and therefore any data can be immediately read from buf.
* buf.mark() may be cleared or updated.
* <p/>
* In the case of an exception, the values of buf.position() and buf.limit()
* are undefined, and callers should be prepared to recover from this
* eventuality.
* <p/>
* Many implementations will throw {@link UnsupportedOperationException}, so
* callers that are not confident in support for this method from the
* underlying filesystem should be prepared to handle that exception.
* <p/>
* Implementations should treat 0-length requests as legitimate, and must not
* signal an error upon their receipt.
*
* @param buf
* the ByteBuffer to receive the results of the read operation. Up to
* buf.limit() - buf.position() bytes may be read.
* @return the number of bytes available to read from buf
* @throws IOException
* if there is some error performing the read
*/
public int read(ByteBuffer buf) throws IOException;
}