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https://issues.apache.org/jira/browse/FLINK-8178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16292518#comment-16292518
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ASF GitHub Bot commented on FLINK-8178:
---------------------------------------
Github user pnowojski commented on a diff in the pull request:
https://github.com/apache/flink/pull/5105#discussion_r157154679
--- 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 --
I will add the test, but I would prefer to leave the `checkState` since
it's purpose is to find bugs and provide early warning about them.
> Introduce not threadsafe write only BufferBuilder
> -------------------------------------------------
>
> Key: FLINK-8178
> URL: https://issues.apache.org/jira/browse/FLINK-8178
> Project: Flink
> Issue Type: Improvement
> Components: Network
> Reporter: Piotr Nowojski
> Assignee: Piotr Nowojski
> Fix For: 1.5.0
>
>
> While Buffer class is used in multithreaded context it requires
> synchronisation. Now it is miss-leading/unclear and suggesting that
> RecordSerializer should take into account synchronisation of the Buffer
> that's holding. With NotThreadSafe BufferBuilder there would be clear
> separation between single-threaded writing/creating a BufferBuilder and
> multithreaded Buffer handling/retaining/recycling.
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