org.apache.hadoop.hdfs.protocol.SystemErasureCodingPolicies Maven / Gradle / Ivy
/**
* 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.hdfs.protocol;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.erasurecode.ErasureCodeConstants;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
/**
* The set of built-in erasure coding policies.
* Although this is a private class, EC policy IDs need to be treated like a
* stable interface. Adding, modifying, or removing built-in policies can cause
* inconsistencies with older clients.
*/
@InterfaceAudience.Private
@InterfaceStability.Stable
public final class SystemErasureCodingPolicies {
// Private constructor, this is a utility class.
private SystemErasureCodingPolicies() {}
// 1 MB
private static final int DEFAULT_CELLSIZE = 1024 * 1024;
public static final byte RS_6_3_POLICY_ID = 1;
private static final ErasureCodingPolicy SYS_POLICY1 =
new ErasureCodingPolicy(ErasureCodeConstants.RS_6_3_SCHEMA,
DEFAULT_CELLSIZE, RS_6_3_POLICY_ID);
public static final byte RS_3_2_POLICY_ID = 2;
private static final ErasureCodingPolicy SYS_POLICY2 =
new ErasureCodingPolicy(ErasureCodeConstants.RS_3_2_SCHEMA,
DEFAULT_CELLSIZE, RS_3_2_POLICY_ID);
public static final byte RS_6_3_LEGACY_POLICY_ID = 3;
private static final ErasureCodingPolicy SYS_POLICY3 =
new ErasureCodingPolicy(ErasureCodeConstants.RS_6_3_LEGACY_SCHEMA,
DEFAULT_CELLSIZE, RS_6_3_LEGACY_POLICY_ID);
public static final byte XOR_2_1_POLICY_ID = 4;
private static final ErasureCodingPolicy SYS_POLICY4 =
new ErasureCodingPolicy(ErasureCodeConstants.XOR_2_1_SCHEMA,
DEFAULT_CELLSIZE, XOR_2_1_POLICY_ID);
public static final byte RS_10_4_POLICY_ID = 5;
private static final ErasureCodingPolicy SYS_POLICY5 =
new ErasureCodingPolicy(ErasureCodeConstants.RS_10_4_SCHEMA,
DEFAULT_CELLSIZE, RS_10_4_POLICY_ID);
// REPLICATION policy is always enabled.
private static final ErasureCodingPolicy REPLICATION_POLICY =
new ErasureCodingPolicy(ErasureCodeConstants.REPLICATION_POLICY_NAME,
ErasureCodeConstants.REPLICATION_1_2_SCHEMA,
DEFAULT_CELLSIZE,
ErasureCodeConstants.REPLICATION_POLICY_ID);
private static final List SYS_POLICIES =
Collections.unmodifiableList(Arrays.asList(
SYS_POLICY1, SYS_POLICY2, SYS_POLICY3, SYS_POLICY4,
SYS_POLICY5));
/**
* System policies sorted by name for fast querying.
*/
private static final Map SYSTEM_POLICIES_BY_NAME;
/**
* System policies sorted by ID for fast querying.
*/
private static final Map SYSTEM_POLICIES_BY_ID;
/**
* Populate the lookup maps in a static block.
*/
static {
SYSTEM_POLICIES_BY_NAME = new TreeMap<>();
SYSTEM_POLICIES_BY_ID = new TreeMap<>();
for (ErasureCodingPolicy policy : SYS_POLICIES) {
SYSTEM_POLICIES_BY_NAME.put(policy.getName(), policy);
SYSTEM_POLICIES_BY_ID.put(policy.getId(), policy);
}
}
/**
* Get system defined policies.
* @return system policies
*/
public static List getPolicies() {
return SYS_POLICIES;
}
/**
* Get a policy by policy ID.
* @return ecPolicy, or null if not found
*/
public static ErasureCodingPolicy getByID(byte id) {
return SYSTEM_POLICIES_BY_ID.get(id);
}
/**
* Get a policy by policy name.
* @return ecPolicy, or null if not found
*/
public static ErasureCodingPolicy getByName(String name) {
return SYSTEM_POLICIES_BY_NAME.get(name);
}
/**
* Get the special REPLICATION policy.
*/
public static ErasureCodingPolicy getReplicationPolicy() {
return REPLICATION_POLICY;
}
}