Github user squito commented on a diff in the pull request:
https://github.com/apache/spark/pull/5400#discussion_r31849284
--- Diff:
network/common/src/main/java/org/apache/spark/network/buffer/LargeByteBuffer.java
---
@@ -0,0 +1,135 @@
+/*
+* 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.spark.network.buffer;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.WritableByteChannel;
+
+/**
+ * A byte buffer which can hold over 2GB.
+ * <p/>
+ * This is roughly similar {@link java.nio.ByteBuffer}, with a limited set
of operations relevant
+ * to use in Spark, and without the capacity restrictions of a ByteBuffer.
+ * <p/>
+ * Unlike ByteBuffers, this is read-only, and only supports reading bytes
(with both single and bulk
+ * <code>get</code> methods). It supports random access via
<code>skip</code> to move around the
+ * buffer.
+ * <p/>
+ * In general, implementations are expected to support O(1) random access.
Furthermore,
+ * neighboring locations in the buffer are likely to be neighboring in
memory, so sequential access
+ * will avoid cache-misses. However, these are only rough guidelines
which may differ in
+ * implementations.
+ * <p/>
+ * Any code which expects a ByteBuffer can obtain one via {@link
#asByteBuffer} when possible -- see
+ * that method for a full description of its limitations.
+ * <p/>
+ * Instances of this class can be created with
+ * {@link org.apache.spark.network.buffer.LargeByteBufferHelper},
+ * with a LargeByteBufferOutputStream,
+ * or directly from the implementation
+ * {@link org.apache.spark.network.buffer.WrappedLargeByteBuffer}.
+ */
+public interface LargeByteBuffer {
+ public byte get();
+
+ /**
+ * Bulk copy data from this buffer into the given array. First checks
there is sufficient
+ * data in this buffer; if not, throws a {@link
java.nio.BufferUnderflowException}.
+ *
+ * @param dst
+ * @param offset
+ * @param length
+ */
+ public void get(byte[] dst, int offset, int length);
+
+ public LargeByteBuffer rewind();
+
+ /**
+ * Return a deep copy of this buffer.
+ * The returned buffer will have position == 0. The position
+ * of this buffer will not change as a result of copying.
+ *
+ * @return a new buffer with a full copy of this buffer's data
+ */
+ public LargeByteBuffer deepCopy();
+
+ /**
+ * Advance the position in this buffer by up to <code>n</code> bytes.
<code>n</code> may be
+ * positive or negative. It will move the full <code>n</code> unless
that moves
+ * it past the end (or beginning) of the buffer, in which case it will
move to the end
+ * (or beginning).
+ *
+ * @return the number of bytes moved forward (can be negative if
<code>n</code> is negative)
+ */
+ public long skip(long n);
+
+ public long position();
+
+ /**
+ * Creates a new byte buffer that shares this buffer's content.
+ * <p/>
+ * The content of the new buffer will be that of this buffer. Changes
+ * to this buffer's content will be visible in the new buffer, and vice
+ * versa; the two buffers' positions will be independent.
+ * <p/>
+ * The new buffer's position will be identical to those of this buffer
+ */
+ public LargeByteBuffer duplicate();
+
+ public long remaining();
+
+ /**
+ * Total number of bytes in this buffer
+ */
+ public long size();
+
+ /**
+ * Writes the data from the current <code>position()</code> to the end
of this buffer
+ * to the given channel. The <code>position()</code> will be moved to
the end of
+ * the buffer after this.
+ * <p/>
+ * Note that this method will continually attempt to push data to the
given channel. If the
+ * channel cannot accept more data, this will continuously retry until
the channel accepts
+ * the data.
+ *
+ * @param channel
+ * @return the number of bytes written to the channel
+ * @throws IOException
+ */
+ public long writeTo(WritableByteChannel channel) throws IOException;
+
+ /**
+ * Get the entire contents of this as one ByteBuffer, if possible. The
returned ByteBuffer
+ * will always have the position set to 0, and the limit set to the end
of the data. Each
+ * call will return a new ByteBuffer, but will not require copying the
data (eg., it will
+ * use ByteBuffer#duplicate()). The returned byte buffer will share
data with this buffer. The
+ * returned buffers will never be larger than
+ * {@link
org.apache.spark.network.buffer.LargeByteBufferHelper#MAX_CHUNK_SIZE}
+ *
+ * @throws BufferTooLargeException if this buffer is too large to fit in
one {@link ByteBuffer}
+ */
+ public ByteBuffer asByteBuffer() throws BufferTooLargeException;
--- End diff --
no problem @chenghao-intel , its good to talk, through this stuff, I have
gone back and forth on the design myself a little. you're input is definitely
helpful :)
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