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https://issues.apache.org/jira/browse/CASSANDRA-14556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16553030#comment-16553030
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ASF GitHub Bot commented on CASSANDRA-14556:
--------------------------------------------
Github user iamaleksey commented on a diff in the pull request:
https://github.com/apache/cassandra/pull/239#discussion_r204457225
--- Diff:
src/java/org/apache/cassandra/db/streaming/CassandraBlockStreamReader.java ---
@@ -0,0 +1,184 @@
+/*
+ * 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.cassandra.db.streaming;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+import java.util.Set;
+
+import com.google.common.base.Throwables;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.cassandra.db.ColumnFamilyStore;
+import org.apache.cassandra.db.DecoratedKey;
+import org.apache.cassandra.db.Directories;
+import org.apache.cassandra.db.SerializationHeader;
+import org.apache.cassandra.db.lifecycle.LifecycleTransaction;
+import org.apache.cassandra.io.sstable.Component;
+import org.apache.cassandra.io.sstable.Descriptor;
+import org.apache.cassandra.io.sstable.SSTableMultiWriter;
+import org.apache.cassandra.io.sstable.format.SSTableFormat;
+import org.apache.cassandra.io.sstable.format.Version;
+import org.apache.cassandra.io.sstable.format.big.BigTableBlockWriter;
+import org.apache.cassandra.io.util.DataInputPlus;
+import org.apache.cassandra.schema.TableId;
+import org.apache.cassandra.streaming.ProgressInfo;
+import org.apache.cassandra.streaming.StreamReceiver;
+import org.apache.cassandra.streaming.StreamSession;
+import org.apache.cassandra.streaming.messages.StreamMessageHeader;
+import org.apache.cassandra.utils.Collectors3;
+import org.apache.cassandra.utils.FBUtilities;
+
+/**
+ * CassandraBlockStreamReader reads SSTable off the wire and writes it to
disk.
+ */
+public class CassandraBlockStreamReader implements IStreamReader
+{
+ private static final Logger logger =
LoggerFactory.getLogger(CassandraBlockStreamReader.class);
+ protected final TableId tableId;
+ protected final StreamSession session;
+ protected final int sstableLevel;
--- End diff --
It has taken me some time (and @krummas's help) to prove that this wasn't a
correctness issue, but at its best this is confusing/misleading code.
We extract `sstableLevel` from the header, but don't use it anywhere.
Instead, since we stream `StatsMetadata` directly, we also inherit the level
from there - regardless of whether `CassandraOutgoingStream.keepSSTableLevel`
is set to `true`. If `LeveledManifest.canAddSSTable` check didn't exist, we'd
be in trouble here. For clarity, I would probably look at that flag, and
explicitly reset the level to `L0` if `keepSSTableLevel` is set to `false`.
P.S. What's the deal with all these `protected` fields?
> Optimize streaming path in Cassandra
> ------------------------------------
>
> Key: CASSANDRA-14556
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14556
> Project: Cassandra
> Issue Type: Improvement
> Components: Streaming and Messaging
> Reporter: Dinesh Joshi
> Assignee: Dinesh Joshi
> Priority: Major
> Labels: Performance
> Fix For: 4.x
>
>
> During streaming, Cassandra reifies the sstables into objects. This creates
> unnecessary garbage and slows down the whole streaming process as some
> sstables can be transferred as a whole file rather than individual
> partitions. The objective of the ticket is to detect when a whole sstable can
> be transferred and skip the object reification. We can also use a zero-copy
> path to avoid bringing data into user-space on both sending and receiving
> side.
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