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    1. /*
    2.  * Licensed to the Apache Software Foundation (ASF) under one
    3.  * or more contributor license agreements.  See the NOTICE file
    4.  * distributed with this work for additional information
    5.  * regarding copyright ownership.  The ASF licenses this file
    6.  * to you under the Apache License, Version 2.0 (the
    7.  * "License"); you may not use this file except in compliance
    8.  * with the License.  You may obtain a copy of the License at
    9.  *
    10.  *     http://www.apache.org/licenses/LICENSE-2.0
    11.  *
    12.  * Unless required by applicable law or agreed to in writing, software
    13.  * distributed under the License is distributed on an "AS IS" BASIS,
    14.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    15.  * See the License for the specific language governing permissions and
    16.  * limitations under the License.
    17.  */
    19. package org.apache.flink.core.memory;
    21. import org.apache.flink.annotation.Public;
    23. import java.io.DataInput;
    24. import java.io.IOException;
    27. /**
    28.  * This interface defines a view over some memory that can be used to sequentially read the contents of the memory.
    29.  * The view is typically backed by one or more {@link org.apache.flink.core.memory.MemorySegment}.
    30.  */
    31. @Public
    32. public interface DataInputView extends DataInput {
    34.     /**
    35.      * Skips {@code numBytes} bytes of memory. In contrast to the {@link #skipBytes(int)} method,
    36.      * this method always skips the desired number of bytes or throws an {@link java.io.EOFException}.
    37.      *
    38.      * @param numBytes The number of bytes to skip.
    39.      *
    40.      * @throws IOException Thrown, if any I/O related problem occurred such that the input could not
    41.      *                     be advanced to the desired position.
    42.      */
    43.     void skipBytesToRead(int numBytes) throws IOException;
    45.     /**
    46.      * Reads up to {@code len} bytes of memory and stores it into {@code b} starting at offset {@code off}.
    47.      * It returns the number of read bytes or -1 if there is no more data left.
    48.      *
    49.      * @param b byte array to store the data to
    50.      * @param off offset into byte array
    51.      * @param len byte length to read
    52.      * @return the number of actually read bytes of -1 if there is no more data left
    53.      * @throws IOException
    54.      */
    55.     int read(byte[] b, int off, int len) throws IOException;
    57.     /**
    58.      * Tries to fill the given byte array {@code b}. Returns the actually number of read bytes or -1 if there is no
    59.      * more data.
    60.      *
    61.      * @param b byte array to store the data to
    62.      * @return the number of read bytes or -1 if there is no more data left
    63.      * @throws IOException
    64.      */
    65.     int read(byte[] b) throws IOException;
    66. }