1 | /** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one |
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3 | * or more contributor license agreements. See the NOTICE file |
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4 | * distributed with this work for additional information |
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5 | * regarding copyright ownership. The ASF licenses this file |
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6 | * to you under the Apache License, Version 2.0 (the |
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7 | * "License"); you may not use this file except in compliance |
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8 | * with the License. You may obtain a copy of the License at |
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9 | * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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11 | * |
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12 | * Unless required by applicable law or agreed to in writing, software |
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13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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15 | * See the License for the specific language governing permissions and |
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16 | * limitations under the License. |
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17 | */ |
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18 | package org.apache.hadoop.hdfs.server.namenode; |
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19 | |
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20 | import java.io.IOException; |
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21 | import java.util.ArrayList; |
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22 | import java.util.Collection; |
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23 | import java.util.List; |
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24 | import java.util.Map; |
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25 | import java.util.SortedMap; |
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26 | import java.util.SortedSet; |
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27 | import java.util.TreeMap; |
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28 | import java.util.TreeSet; |
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29 | |
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30 | import org.apache.commons.logging.Log; |
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31 | import org.apache.commons.logging.LogFactory; |
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32 | import org.apache.hadoop.fs.Path; |
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33 | import org.apache.hadoop.hdfs.protocol.FSConstants; |
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34 | |
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35 | /** |
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36 | * LeaseManager does the lease housekeeping for writing on files. |
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37 | * This class also provides useful static methods for lease recovery. |
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38 | * |
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39 | * Lease Recovery Algorithm |
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40 | * 1) Namenode retrieves lease information |
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41 | * 2) For each file f in the lease, consider the last block b of f |
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42 | * 2.1) Get the datanodes which contains b |
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43 | * 2.2) Assign one of the datanodes as the primary datanode p |
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44 | |
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45 | * 2.3) p obtains a new generation stamp form the namenode |
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46 | * 2.4) p get the block info from each datanode |
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47 | * 2.5) p computes the minimum block length |
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48 | * 2.6) p updates the datanodes, which have a valid generation stamp, |
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49 | * with the new generation stamp and the minimum block length |
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50 | * 2.7) p acknowledges the namenode the update results |
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51 | |
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52 | * 2.8) Namenode updates the BlockInfo |
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53 | * 2.9) Namenode removes f from the lease |
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54 | * and removes the lease once all files have been removed |
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55 | * 2.10) Namenode commit changes to edit log |
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56 | */ |
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57 | public class LeaseManager { |
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58 | public static final Log LOG = LogFactory.getLog(LeaseManager.class); |
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59 | |
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60 | private final FSNamesystem fsnamesystem; |
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61 | |
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62 | private long softLimit = FSConstants.LEASE_SOFTLIMIT_PERIOD; |
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63 | private long hardLimit = FSConstants.LEASE_HARDLIMIT_PERIOD; |
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64 | |
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65 | // |
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66 | // Used for handling lock-leases |
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67 | // Mapping: leaseHolder -> Lease |
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68 | // |
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69 | private SortedMap<String, Lease> leases = new TreeMap<String, Lease>(); |
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70 | // Set of: Lease |
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71 | private SortedSet<Lease> sortedLeases = new TreeSet<Lease>(); |
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72 | |
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73 | // |
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74 | // Map path names to leases. It is protected by the sortedLeases lock. |
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75 | // The map stores pathnames in lexicographical order. |
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76 | // |
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77 | private SortedMap<String, Lease> sortedLeasesByPath = new TreeMap<String, Lease>(); |
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78 | |
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79 | LeaseManager(FSNamesystem fsnamesystem) {this.fsnamesystem = fsnamesystem;} |
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80 | |
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81 | Lease getLease(String holder) { |
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82 | return leases.get(holder); |
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83 | } |
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84 | |
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85 | SortedSet<Lease> getSortedLeases() {return sortedLeases;} |
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86 | |
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87 | /** @return the lease containing src */ |
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88 | public Lease getLeaseByPath(String src) {return sortedLeasesByPath.get(src);} |
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89 | |
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90 | /** @return the number of leases currently in the system */ |
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91 | public synchronized int countLease() {return sortedLeases.size();} |
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92 | |
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93 | /** @return the number of paths contained in all leases */ |
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94 | synchronized int countPath() { |
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95 | int count = 0; |
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96 | for(Lease lease : sortedLeases) { |
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97 | count += lease.getPaths().size(); |
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98 | } |
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99 | return count; |
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100 | } |
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101 | |
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102 | /** |
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103 | * Adds (or re-adds) the lease for the specified file. |
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104 | */ |
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105 | synchronized void addLease(String holder, String src) { |
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106 | Lease lease = getLease(holder); |
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107 | if (lease == null) { |
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108 | lease = new Lease(holder); |
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109 | leases.put(holder, lease); |
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110 | sortedLeases.add(lease); |
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111 | } else { |
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112 | renewLease(lease); |
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113 | } |
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114 | sortedLeasesByPath.put(src, lease); |
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115 | lease.paths.add(src); |
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116 | } |
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117 | |
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118 | /** |
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119 | * Remove the specified lease and src. |
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120 | */ |
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121 | synchronized void removeLease(Lease lease, String src) { |
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122 | sortedLeasesByPath.remove(src); |
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123 | if (!lease.removePath(src)) { |
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124 | LOG.error(src + " not found in lease.paths (=" + lease.paths + ")"); |
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125 | } |
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126 | |
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127 | if (!lease.hasPath()) { |
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128 | leases.remove(lease.holder); |
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129 | if (!sortedLeases.remove(lease)) { |
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130 | LOG.error(lease + " not found in sortedLeases"); |
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131 | } |
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132 | } |
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133 | } |
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134 | |
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135 | /** |
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136 | * Remove the lease for the specified holder and src |
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137 | */ |
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138 | synchronized void removeLease(String holder, String src) { |
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139 | Lease lease = getLease(holder); |
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140 | if (lease != null) { |
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141 | removeLease(lease, src); |
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142 | } |
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143 | } |
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144 | |
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145 | /** |
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146 | * Finds the pathname for the specified pendingFile |
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147 | */ |
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148 | synchronized String findPath(INodeFileUnderConstruction pendingFile |
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149 | ) throws IOException { |
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150 | Lease lease = getLease(pendingFile.clientName); |
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151 | if (lease != null) { |
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152 | String src = lease.findPath(pendingFile); |
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153 | if (src != null) { |
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154 | return src; |
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155 | } |
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156 | } |
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157 | throw new IOException("pendingFile (=" + pendingFile + ") not found." |
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158 | + "(lease=" + lease + ")"); |
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159 | } |
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160 | |
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161 | /** |
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162 | * Renew the lease(s) held by the given client |
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163 | */ |
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164 | synchronized void renewLease(String holder) { |
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165 | renewLease(getLease(holder)); |
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166 | } |
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167 | synchronized void renewLease(Lease lease) { |
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168 | if (lease != null) { |
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169 | sortedLeases.remove(lease); |
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170 | lease.renew(); |
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171 | sortedLeases.add(lease); |
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172 | } |
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173 | } |
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174 | |
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175 | /************************************************************ |
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176 | * A Lease governs all the locks held by a single client. |
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177 | * For each client there's a corresponding lease, whose |
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178 | * timestamp is updated when the client periodically |
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179 | * checks in. If the client dies and allows its lease to |
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180 | * expire, all the corresponding locks can be released. |
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181 | *************************************************************/ |
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182 | class Lease implements Comparable<Lease> { |
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183 | private final String holder; |
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184 | private long lastUpdate; |
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185 | private final Collection<String> paths = new TreeSet<String>(); |
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186 | |
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187 | /** Only LeaseManager object can create a lease */ |
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188 | private Lease(String holder) { |
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189 | this.holder = holder; |
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190 | renew(); |
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191 | } |
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192 | /** Only LeaseManager object can renew a lease */ |
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193 | private void renew() { |
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194 | this.lastUpdate = FSNamesystem.now(); |
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195 | } |
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196 | |
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197 | /** @return true if the Hard Limit Timer has expired */ |
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198 | public boolean expiredHardLimit() { |
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199 | return FSNamesystem.now() - lastUpdate > hardLimit; |
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200 | } |
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201 | |
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202 | /** @return true if the Soft Limit Timer has expired */ |
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203 | public boolean expiredSoftLimit() { |
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204 | return FSNamesystem.now() - lastUpdate > softLimit; |
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205 | } |
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206 | |
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207 | /** |
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208 | * @return the path associated with the pendingFile and null if not found. |
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209 | */ |
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210 | private String findPath(INodeFileUnderConstruction pendingFile) { |
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211 | for(String src : paths) { |
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212 | if (fsnamesystem.dir.getFileINode(src) == pendingFile) { |
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213 | return src; |
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214 | } |
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215 | } |
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216 | return null; |
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217 | } |
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218 | |
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219 | /** Does this lease contain any path? */ |
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220 | boolean hasPath() {return !paths.isEmpty();} |
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221 | |
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222 | boolean removePath(String src) { |
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223 | return paths.remove(src); |
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224 | } |
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225 | |
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226 | /** {@inheritDoc} */ |
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227 | public String toString() { |
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228 | return "[Lease. Holder: " + holder |
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229 | + ", pendingcreates: " + paths.size() + "]"; |
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230 | } |
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231 | |
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232 | /** {@inheritDoc} */ |
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233 | public int compareTo(Lease o) { |
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234 | Lease l1 = this; |
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235 | Lease l2 = o; |
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236 | long lu1 = l1.lastUpdate; |
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237 | long lu2 = l2.lastUpdate; |
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238 | if (lu1 < lu2) { |
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239 | return -1; |
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240 | } else if (lu1 > lu2) { |
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241 | return 1; |
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242 | } else { |
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243 | return l1.holder.compareTo(l2.holder); |
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244 | } |
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245 | } |
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246 | |
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247 | /** {@inheritDoc} */ |
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248 | public boolean equals(Object o) { |
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249 | if (!(o instanceof Lease)) { |
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250 | return false; |
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251 | } |
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252 | Lease obj = (Lease) o; |
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253 | if (lastUpdate == obj.lastUpdate && |
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254 | holder.equals(obj.holder)) { |
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255 | return true; |
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256 | } |
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257 | return false; |
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258 | } |
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259 | |
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260 | /** {@inheritDoc} */ |
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261 | public int hashCode() { |
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262 | return holder.hashCode(); |
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263 | } |
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264 | |
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265 | Collection<String> getPaths() { |
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266 | return paths; |
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267 | } |
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268 | |
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269 | void replacePath(String oldpath, String newpath) { |
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270 | paths.remove(oldpath); |
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271 | paths.add(newpath); |
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272 | } |
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273 | } |
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274 | |
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275 | synchronized void changeLease(String src, String dst, |
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276 | String overwrite, String replaceBy) { |
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277 | if (LOG.isDebugEnabled()) { |
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278 | LOG.debug(getClass().getSimpleName() + ".changelease: " + |
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279 | " src=" + src + ", dest=" + dst + |
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280 | ", overwrite=" + overwrite + |
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281 | ", replaceBy=" + replaceBy); |
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282 | } |
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283 | |
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284 | final int len = overwrite.length(); |
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285 | for(Map.Entry<String, Lease> entry : findLeaseWithPrefixPath(src, sortedLeasesByPath)) { |
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286 | final String oldpath = entry.getKey(); |
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287 | final Lease lease = entry.getValue(); |
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288 | //overwrite must be a prefix of oldpath |
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289 | final String newpath = replaceBy + oldpath.substring(len); |
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290 | if (LOG.isDebugEnabled()) { |
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291 | LOG.debug("changeLease: replacing " + oldpath + " with " + newpath); |
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292 | } |
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293 | lease.replacePath(oldpath, newpath); |
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294 | sortedLeasesByPath.remove(oldpath); |
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295 | sortedLeasesByPath.put(newpath, lease); |
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296 | } |
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297 | } |
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298 | |
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299 | synchronized void removeLeaseWithPrefixPath(String prefix) { |
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300 | for(Map.Entry<String, Lease> entry : findLeaseWithPrefixPath(prefix, sortedLeasesByPath)) { |
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301 | if (LOG.isDebugEnabled()) { |
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302 | LOG.debug(LeaseManager.class.getSimpleName() |
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303 | + ".removeLeaseWithPrefixPath: entry=" + entry); |
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304 | } |
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305 | removeLease(entry.getValue(), entry.getKey()); |
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306 | } |
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307 | } |
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308 | |
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309 | static private List<Map.Entry<String, Lease>> findLeaseWithPrefixPath( |
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310 | String prefix, SortedMap<String, Lease> path2lease) { |
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311 | if (LOG.isDebugEnabled()) { |
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312 | LOG.debug(LeaseManager.class.getSimpleName() + ".findLease: prefix=" + prefix); |
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313 | } |
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314 | |
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315 | List<Map.Entry<String, Lease>> entries = new ArrayList<Map.Entry<String, Lease>>(); |
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316 | final int srclen = prefix.length(); |
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317 | |
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318 | for(Map.Entry<String, Lease> entry : path2lease.tailMap(prefix).entrySet()) { |
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319 | final String p = entry.getKey(); |
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320 | if (!p.startsWith(prefix)) { |
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321 | return entries; |
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322 | } |
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323 | if (p.length() == srclen || p.charAt(srclen) == Path.SEPARATOR_CHAR) { |
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324 | entries.add(entry); |
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325 | } |
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326 | } |
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327 | return entries; |
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328 | } |
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329 | |
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330 | public void setLeasePeriod(long softLimit, long hardLimit) { |
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331 | this.softLimit = softLimit; |
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332 | this.hardLimit = hardLimit; |
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333 | } |
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334 | |
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335 | /****************************************************** |
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336 | * Monitor checks for leases that have expired, |
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337 | * and disposes of them. |
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338 | ******************************************************/ |
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339 | class Monitor implements Runnable { |
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340 | final String name = getClass().getSimpleName(); |
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341 | |
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342 | /** Check leases periodically. */ |
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343 | public void run() { |
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344 | for(; fsnamesystem.isRunning(); ) { |
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345 | synchronized(fsnamesystem) { |
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346 | checkLeases(); |
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347 | } |
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348 | |
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349 | try { |
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350 | Thread.sleep(2000); |
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351 | } catch(InterruptedException ie) { |
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352 | if (LOG.isDebugEnabled()) { |
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353 | LOG.debug(name + " is interrupted", ie); |
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354 | } |
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355 | } |
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356 | } |
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357 | } |
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358 | } |
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359 | |
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360 | /** Check the leases beginning from the oldest. */ |
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361 | private synchronized void checkLeases() { |
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362 | for(; sortedLeases.size() > 0; ) { |
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363 | final Lease oldest = sortedLeases.first(); |
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364 | if (!oldest.expiredHardLimit()) { |
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365 | return; |
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366 | } |
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367 | |
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368 | LOG.info("Lease " + oldest + " has expired hard limit"); |
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369 | |
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370 | final List<String> removing = new ArrayList<String>(); |
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371 | // need to create a copy of the oldest lease paths, becuase |
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372 | // internalReleaseLease() removes paths corresponding to empty files, |
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373 | // i.e. it needs to modify the collection being iterated over |
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374 | // causing ConcurrentModificationException |
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375 | String[] leasePaths = new String[oldest.getPaths().size()]; |
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376 | oldest.getPaths().toArray(leasePaths); |
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377 | for(String p : leasePaths) { |
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378 | try { |
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379 | fsnamesystem.internalReleaseLease(oldest, p); |
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380 | } catch (IOException e) { |
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381 | LOG.error("Cannot release the path "+p+" in the lease "+oldest, e); |
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382 | removing.add(p); |
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383 | } |
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384 | } |
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385 | |
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386 | for(String p : removing) { |
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387 | removeLease(oldest, p); |
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388 | } |
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389 | } |
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390 | } |
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391 | |
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392 | /** {@inheritDoc} */ |
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393 | public synchronized String toString() { |
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394 | return getClass().getSimpleName() + "= {" |
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395 | + "\n leases=" + leases |
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396 | + "\n sortedLeases=" + sortedLeases |
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397 | + "\n sortedLeasesByPath=" + sortedLeasesByPath |
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398 | + "\n}"; |
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399 | } |
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400 | } |
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