maedhroz commented on code in PR #1723: URL: https://github.com/apache/cassandra/pull/1723#discussion_r997380361
########## src/java/org/apache/cassandra/db/memtable/AbstractShardedMemtable.java: ########## @@ -0,0 +1,103 @@ +/* + * 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.memtable; + +import java.util.concurrent.atomic.AtomicReference; + +import com.google.common.annotations.VisibleForTesting; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import org.apache.cassandra.db.commitlog.CommitLogPosition; +import org.apache.cassandra.schema.TableMetadataRef; +import org.apache.cassandra.utils.FBUtilities; +import org.apache.cassandra.utils.MBeanWrapper; +import org.github.jamm.Unmetered; + +public abstract class AbstractShardedMemtable extends AbstractAllocatorMemtable +{ + private static final Logger logger = LoggerFactory.getLogger(AbstractShardedMemtable.class); + + public static final String SHARDS_OPTION = "shards"; + @VisibleForTesting + public static final String DEFAULT_SHARD_COUNT_PROPERTY = "cassandra.memtable.shard.count"; + + public static final String SHARDED_MEMTABLE_CONFIG_OBJECT_NAME = "org.apache.cassandra.db:type=ShardedMemtableConfig"; + static + { + MBeanWrapper.instance.registerMBean(new ShardedMemtableConfig(), SHARDED_MEMTABLE_CONFIG_OBJECT_NAME, MBeanWrapper.OnException.LOG); + } + + // default shard count, used when a specific number of shards is not specified in the options + private static volatile int defaultShardCount = Integer.getInteger(DEFAULT_SHARD_COUNT_PROPERTY, FBUtilities.getAvailableProcessors()); + + // The boundaries for the keyspace as they were calculated when the memtable is created. + // The boundaries will be NONE for system keyspaces or if StorageService is not yet initialized. + // The fact this is fixed for the duration of the memtable lifetime, guarantees we'll always pick the same shard + // for a given key, even if we race with the StorageService initialization or with topology changes. + @Unmetered + protected final ShardBoundaries boundaries; + + AbstractShardedMemtable(AtomicReference<CommitLogPosition> commitLogLowerBound, + TableMetadataRef metadataRef, + Owner owner, + Integer shardCountOption) + { + super(commitLogLowerBound, metadataRef, owner); + int shardCount = shardCountOption != null ? shardCountOption : defaultShardCount; + this.boundaries = owner.localRangeSplits(shardCount); + } + + private static class ShardedMemtableConfig implements ShardedMemtableConfigMXBean + { + @Override + public void setDefaultShardCount(String shardCount) + { + if ("auto".equalsIgnoreCase(shardCount)) + { + defaultShardCount = FBUtilities.getAvailableProcessors(); + } + else + { + try + { + defaultShardCount = Integer.valueOf(shardCount); Review Comment: ```suggestion defaultShardCount = Integer.parseInt(shardCount); ``` Not that this is a hot path or anything :D -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
