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From: NicoK <git@git.apache.org>
To: issues@flink.incubator.apache.org
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Subject: [GitHub] flink pull request #5105: [FLINK-8178][network] Introduce not threadsafe wri...
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Message-Id: <20171212170547.BED61E96ED@git1-us-west.apache.org>
Date: Tue, 12 Dec 2017 17:05:47 +0000 (UTC)
archived-at: Tue, 12 Dec 2017 17:05:56 -0000

Github user NicoK commented on a diff in the pull request:

    https://github.com/apache/flink/pull/5105#discussion_r156418759
  
    --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/buffer/BufferBuilder.java ---
    @@ -0,0 +1,80 @@
    +/*
    + * 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.io.network.buffer;
    +
    +import org.apache.flink.core.memory.MemorySegment;
    +
    +import javax.annotation.concurrent.NotThreadSafe;
    +
    +import java.nio.ByteBuffer;
    +
    +import static org.apache.flink.util.Preconditions.checkNotNull;
    +import static org.apache.flink.util.Preconditions.checkState;
    +
    +/**
    + * Not thread safe class for filling in the initial content of the {@link Buffer}. Once writing to the builder
    + * is complete, {@link Buffer} instance can be built and shared across multiple threads.
    + */
    +@NotThreadSafe
    +public class BufferBuilder {
    +	private final MemorySegment memorySegment;
    +
    +	private final BufferRecycler recycler;
    +
    +	private int position = 0;
    +
    +	private boolean built = false;
    +
    +	public BufferBuilder(MemorySegment memorySegment, BufferRecycler recycler) {
    +		this.memorySegment = checkNotNull(memorySegment);
    +		this.recycler = checkNotNull(recycler);
    +	}
    +
    +	public void append(ByteBuffer source) {
    +		checkState(!built);
    +
    +		int needed = source.remaining();
    +		int available = limit() - position;
    +		int toCopy = Math.min(needed, available);
    +
    +		memorySegment.put(position, source, toCopy);
    +		position += toCopy;
    +	}
    --- End diff --
    
    in a test, please also verify that we cannot add to a full buffer - in that case, you can also drop the `checkState` in the `isFull()` method below


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