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Server functionality for HBase
/*
* 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.hadoop.hbase.regionserver;
import java.io.IOException;
import java.util.List;
import java.util.Optional;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.hbase.HBaseInterfaceAudience;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
/**
* A split policy determines when a Region should be split.
* @see SteppingSplitPolicy Default split policy since 2.0.0
* @see IncreasingToUpperBoundRegionSplitPolicy Default split policy since 0.94.0
* @see ConstantSizeRegionSplitPolicy Default split policy before 0.94.0
*/
@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
public abstract class RegionSplitPolicy extends Configured {
private static final Class DEFAULT_SPLIT_POLICY_CLASS =
SteppingSplitPolicy.class;
/**
* The region configured for this split policy. As of hbase-2.0.0, RegionSplitPolicy can be
* instantiated on the Master-side so the Phoenix local-indexer can block default hbase behavior.
* This is an exotic usage. Should not trouble any other users of RegionSplitPolicy.
*/
protected HRegion region;
/**
* Upon construction, this method will be called with the region to be governed. It will be called
* once and only once.
*/
protected void configureForRegion(HRegion region) {
Preconditions.checkState(this.region == null, "Policy already configured for region {}",
this.region);
this.region = region;
}
/** Returns true if the specified region should be split. */
protected abstract boolean shouldSplit();
/** Returns {@code true} if the specified region can be split. */
protected boolean canSplit() {
return !region.getRegionInfo().isMetaRegion() && region.isAvailable()
&& !TableName.NAMESPACE_TABLE_NAME.equals(region.getRegionInfo().getTable())
&& region.getStores().stream().allMatch(HStore::canSplit);
}
/**
* @return the key at which the region should be split, or null if it cannot be split. This will
* only be called if shouldSplit previously returned true.
*/
protected byte[] getSplitPoint() {
List stores = region.getStores();
byte[] splitPointFromLargestStore = null;
long largestStoreSize = 0;
for (HStore s : stores) {
Optional splitPoint = s.getSplitPoint();
// Store also returns null if it has references as way of indicating it is not splittable
long storeSize = s.getSize();
if (splitPoint.isPresent() && largestStoreSize < storeSize) {
splitPointFromLargestStore = splitPoint.get();
largestStoreSize = storeSize;
}
}
return splitPointFromLargestStore;
}
/**
* Create the RegionSplitPolicy configured for the given table.
* @return a RegionSplitPolicy
*/
public static RegionSplitPolicy create(HRegion region, Configuration conf) throws IOException {
Preconditions.checkNotNull(region, "Region should not be null.");
Class clazz =
getSplitPolicyClass(region.getTableDescriptor(), conf);
RegionSplitPolicy policy = ReflectionUtils.newInstance(clazz, conf);
policy.configureForRegion(region);
return policy;
}
public static Class getSplitPolicyClass(TableDescriptor htd,
Configuration conf) throws IOException {
String className = htd.getRegionSplitPolicyClassName();
if (className == null) {
className =
conf.get(HConstants.HBASE_REGION_SPLIT_POLICY_KEY, DEFAULT_SPLIT_POLICY_CLASS.getName());
}
try {
Class clazz =
Class.forName(className).asSubclass(RegionSplitPolicy.class);
return clazz;
} catch (Exception e) {
throw new IOException("Unable to load configured region split policy '" + className
+ "' for table '" + htd.getTableName() + "'", e);
}
}
/**
* In
* {@link HRegionFileSystem#splitStoreFile(org.apache.hadoop.hbase.client.RegionInfo, String, HStoreFile, byte[], boolean, RegionSplitPolicy)}
* we are not creating the split reference if split row does not lie inside the StoreFile range.
* But in some use cases we may need to create the split reference even when the split row does
* not lie inside the StoreFile range. This method can be used to decide, whether to skip the the
* StoreFile range check or not.
*
* This method is not for general use. It is a mechanism put in place by Phoenix local indexing to
* defeat standard hbase behaviors. Phoenix local indices are very likely the only folks who would
* make use of this method. On the Master-side, we will instantiate a RegionSplitPolicy instance
* and run this method ONLY... none of the others make sense on the Master-side.
*
* TODO: Shutdown this phoenix specialization or do it via some other means.
* @return whether to skip the StoreFile range check or not
*/
protected boolean skipStoreFileRangeCheck(String familyName) {
return false;
}
}