001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 package org.apache.hadoop.hdfs.protocol;
019
020 import org.apache.hadoop.classification.InterfaceAudience;
021 import org.apache.hadoop.hdfs.DFSConfigKeys;
022 import org.apache.hadoop.hdfs.HdfsConfiguration;
023
024 /************************************
025 * Some handy constants
026 *
027 ************************************/
028 @InterfaceAudience.Private
029 public class HdfsConstants {
030 /* Hidden constructor */
031 protected HdfsConstants() {
032 }
033
034 /**
035 * HDFS Protocol Names:
036 */
037 public static final String CLIENT_NAMENODE_PROTOCOL_NAME =
038 "org.apache.hadoop.hdfs.protocol.ClientProtocol";
039 public static final String CLIENT_DATANODE_PROTOCOL_NAME =
040 "org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol";
041
042
043 public static int MIN_BLOCKS_FOR_WRITE = 5;
044
045 // Long that indicates "leave current quota unchanged"
046 public static final long QUOTA_DONT_SET = Long.MAX_VALUE;
047 public static final long QUOTA_RESET = -1L;
048
049 //
050 // Timeouts, constants
051 //
052 public static final long LEASE_SOFTLIMIT_PERIOD = 60 * 1000;
053 public static final long LEASE_HARDLIMIT_PERIOD = 60 * LEASE_SOFTLIMIT_PERIOD;
054 public static final long LEASE_RECOVER_PERIOD = 10 * 1000; // in ms
055
056 // We need to limit the length and depth of a path in the filesystem.
057 // HADOOP-438
058 // Currently we set the maximum length to 8k characters and the maximum depth
059 // to 1k.
060 public static int MAX_PATH_LENGTH = 8000;
061 public static int MAX_PATH_DEPTH = 1000;
062
063 // TODO should be conf injected?
064 public static final int DEFAULT_DATA_SOCKET_SIZE = 128 * 1024;
065 public static final int IO_FILE_BUFFER_SIZE = new HdfsConfiguration().getInt(
066 DFSConfigKeys.IO_FILE_BUFFER_SIZE_KEY,
067 DFSConfigKeys.IO_FILE_BUFFER_SIZE_DEFAULT);
068 // Used for writing header etc.
069 public static final int SMALL_BUFFER_SIZE = Math.min(IO_FILE_BUFFER_SIZE / 2,
070 512);
071
072 public static final int BYTES_IN_INTEGER = Integer.SIZE / Byte.SIZE;
073
074 // SafeMode actions
075 public static enum SafeModeAction {
076 SAFEMODE_LEAVE, SAFEMODE_ENTER, SAFEMODE_GET;
077 }
078
079 // type of the datanode report
080 public static enum DatanodeReportType {
081 ALL, LIVE, DEAD
082 }
083
084 // An invalid transaction ID that will never be seen in a real namesystem.
085 public static final long INVALID_TXID = -12345;
086
087 /**
088 * URI Scheme for hdfs://namenode/ URIs.
089 */
090 public static final String HDFS_URI_SCHEME = "hdfs";
091
092 /**
093 * A prefix put before the namenode URI inside the "service" field
094 * of a delgation token, indicating that the URI is a logical (HA)
095 * URI.
096 */
097 public static final String HA_DT_SERVICE_PREFIX = "ha-hdfs:";
098
099
100 /**
101 * Please see {@link LayoutVersion} on adding new layout version.
102 */
103 public static final int LAYOUT_VERSION = LayoutVersion
104 .getCurrentLayoutVersion();
105 }