Java tutorial
/** * 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.server.blockmanagement; import com.google.common.annotations.VisibleForTesting; import com.google.common.base.Preconditions; import com.google.common.collect.Lists; import org.apache.hadoop.fs.StorageType; import org.apache.hadoop.fs.XAttr; import org.apache.hadoop.hdfs.XAttrHelper; import org.apache.hadoop.hdfs.protocol.BlockStoragePolicy; import org.apache.hadoop.hdfs.protocol.HdfsConstants; import org.apache.hadoop.util.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.List; /** A collection of block storage policies. */ public class BlockStoragePolicySuite { static final Logger LOG = LoggerFactory.getLogger(BlockStoragePolicySuite.class); public static final String STORAGE_POLICY_XATTR_NAME = "hsm.block.storage.policy.id"; public static final XAttr.NameSpace XAttrNS = XAttr.NameSpace.SYSTEM; public static final int ID_BIT_LENGTH = 4; @VisibleForTesting public static BlockStoragePolicySuite createDefaultSuite() { final BlockStoragePolicy[] policies = new BlockStoragePolicy[1 << ID_BIT_LENGTH]; final byte lazyPersistId = HdfsConstants.MEMORY_STORAGE_POLICY_ID; policies[lazyPersistId] = new BlockStoragePolicy(lazyPersistId, HdfsConstants.MEMORY_STORAGE_POLICY_NAME, new StorageType[] { StorageType.RAM_DISK, StorageType.DISK }, new StorageType[] { StorageType.DISK }, new StorageType[] { StorageType.DISK }, true); // Cannot be changed on regular files, but inherited. final byte allssdId = HdfsConstants.ALLSSD_STORAGE_POLICY_ID; policies[allssdId] = new BlockStoragePolicy(allssdId, HdfsConstants.ALLSSD_STORAGE_POLICY_NAME, new StorageType[] { StorageType.SSD }, new StorageType[] { StorageType.DISK }, new StorageType[] { StorageType.DISK }); final byte onessdId = HdfsConstants.ONESSD_STORAGE_POLICY_ID; policies[onessdId] = new BlockStoragePolicy(onessdId, HdfsConstants.ONESSD_STORAGE_POLICY_NAME, new StorageType[] { StorageType.SSD, StorageType.DISK }, new StorageType[] { StorageType.SSD, StorageType.DISK }, new StorageType[] { StorageType.SSD, StorageType.DISK }); final byte hotId = HdfsConstants.HOT_STORAGE_POLICY_ID; policies[hotId] = new BlockStoragePolicy(hotId, HdfsConstants.HOT_STORAGE_POLICY_NAME, new StorageType[] { StorageType.DISK }, StorageType.EMPTY_ARRAY, new StorageType[] { StorageType.ARCHIVE }); final byte warmId = HdfsConstants.WARM_STORAGE_POLICY_ID; policies[warmId] = new BlockStoragePolicy(warmId, HdfsConstants.WARM_STORAGE_POLICY_NAME, new StorageType[] { StorageType.DISK, StorageType.ARCHIVE }, new StorageType[] { StorageType.DISK, StorageType.ARCHIVE }, new StorageType[] { StorageType.DISK, StorageType.ARCHIVE }); final byte coldId = HdfsConstants.COLD_STORAGE_POLICY_ID; policies[coldId] = new BlockStoragePolicy(coldId, HdfsConstants.COLD_STORAGE_POLICY_NAME, new StorageType[] { StorageType.ARCHIVE }, StorageType.EMPTY_ARRAY, StorageType.EMPTY_ARRAY); final byte providedId = HdfsConstants.PROVIDED_STORAGE_POLICY_ID; policies[providedId] = new BlockStoragePolicy(providedId, HdfsConstants.PROVIDED_STORAGE_POLICY_NAME, new StorageType[] { StorageType.PROVIDED, StorageType.DISK }, new StorageType[] { StorageType.PROVIDED, StorageType.DISK }, new StorageType[] { StorageType.PROVIDED, StorageType.DISK }); return new BlockStoragePolicySuite(hotId, policies); } private final byte defaultPolicyID; private final BlockStoragePolicy[] policies; public BlockStoragePolicySuite(byte defaultPolicyID, BlockStoragePolicy[] policies) { this.defaultPolicyID = defaultPolicyID; this.policies = policies; } /** @return the corresponding policy. */ public BlockStoragePolicy getPolicy(byte id) { // id == 0 means policy not specified. return id == 0 ? getDefaultPolicy() : policies[id]; } /** @return the default policy. */ public BlockStoragePolicy getDefaultPolicy() { return getPolicy(defaultPolicyID); } public BlockStoragePolicy getPolicy(String policyName) { Preconditions.checkNotNull(policyName); if (policies != null) { for (BlockStoragePolicy policy : policies) { if (policy != null && policy.getName().equalsIgnoreCase(policyName)) { return policy; } } } return null; } public BlockStoragePolicy[] getAllPolicies() { List<BlockStoragePolicy> list = Lists.newArrayList(); if (policies != null) { for (BlockStoragePolicy policy : policies) { if (policy != null) { list.add(policy); } } } return list.toArray(new BlockStoragePolicy[list.size()]); } public static String buildXAttrName() { return StringUtils.toLowerCase(XAttrNS.toString()) + "." + STORAGE_POLICY_XATTR_NAME; } public static XAttr buildXAttr(byte policyId) { final String name = buildXAttrName(); return XAttrHelper.buildXAttr(name, new byte[] { policyId }); } public static String getStoragePolicyXAttrPrefixedName() { return XAttrHelper.getPrefixedName(XAttrNS, STORAGE_POLICY_XATTR_NAME); } }