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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase;
19  
20  import static org.apache.hadoop.hbase.io.hfile.BlockType.MAGIC_LENGTH;
21  
22  import java.nio.ByteBuffer;
23  import java.nio.charset.Charset;
24  import java.util.Arrays;
25  import java.util.Collections;
26  import java.util.List;
27  import java.util.UUID;
28  import java.util.regex.Pattern;
29  
30  import org.apache.commons.lang.ArrayUtils;
31  import org.apache.hadoop.classification.InterfaceAudience;
32  import org.apache.hadoop.classification.InterfaceStability;
33  import org.apache.hadoop.hbase.util.Bytes;
34  
35  /**
36   * HConstants holds a bunch of HBase-related constants
37   */
38  @InterfaceAudience.Public
39  @InterfaceStability.Stable
40  public final class HConstants {
41    //Bytes.UTF8_ENCODING should be updated if this changed
42    /** When we encode strings, we always specify UTF8 encoding */
43    public static final String UTF8_ENCODING = "UTF-8";
44  
45    //Bytes.UTF8_CHARSET should be updated if this changed
46    /** When we encode strings, we always specify UTF8 encoding */
47    public static final Charset UTF8_CHARSET = Charset.forName(UTF8_ENCODING);
48    /**
49     * Default block size for an HFile.
50     */
51    public final static int DEFAULT_BLOCKSIZE = 64 * 1024;
52  
53    /** Used as a magic return value while optimized index key feature enabled(HBASE-7845) */
54    public final static int INDEX_KEY_MAGIC = -2;
55    /*
56       * Name of directory that holds recovered edits written by the wal log
57       * splitting code, one per region
58       */
59    public static final String RECOVERED_EDITS_DIR = "recovered.edits";
60    /**
61     * The first four bytes of Hadoop RPC connections
62     */
63    public static final ByteBuffer RPC_HEADER = ByteBuffer.wrap("HBas".getBytes());
64    public static final byte RPC_CURRENT_VERSION = 0;
65  
66    // HFileBlock constants.
67  
68    /** The size data structures with minor version is 0 */
69    public static final int HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM = MAGIC_LENGTH + 2 * Bytes.SIZEOF_INT
70        + Bytes.SIZEOF_LONG;
71    /** The size of a version 2 HFile block header, minor version 1.
72     * There is a 1 byte checksum type, followed by a 4 byte bytesPerChecksum
73     * followed by another 4 byte value to store sizeofDataOnDisk.
74     */
75    public static final int HFILEBLOCK_HEADER_SIZE = HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM +
76      Bytes.SIZEOF_BYTE + 2 * Bytes.SIZEOF_INT;
77    /** Just an array of bytes of the right size. */
78    public static final byte[] HFILEBLOCK_DUMMY_HEADER = new byte[HFILEBLOCK_HEADER_SIZE];
79  
80    //End HFileBlockConstants.
81  
82    /**
83     * Status codes used for return values of bulk operations.
84     */
85    public enum OperationStatusCode {
86      NOT_RUN,
87      SUCCESS,
88      BAD_FAMILY,
89      SANITY_CHECK_FAILURE,
90      FAILURE;
91    }
92  
93    /** long constant for zero */
94    public static final Long ZERO_L = Long.valueOf(0L);
95    public static final String NINES = "99999999999999";
96    public static final String ZEROES = "00000000000000";
97  
98    // For migration
99  
100   /** name of version file */
101   public static final String VERSION_FILE_NAME = "hbase.version";
102 
103   /**
104    * Current version of file system.
105    * Version 4 supports only one kind of bloom filter.
106    * Version 5 changes versions in catalog table regions.
107    * Version 6 enables blockcaching on catalog tables.
108    * Version 7 introduces hfile -- hbase 0.19 to 0.20..
109    * Version 8 introduces namespace
110    */
111   // public static final String FILE_SYSTEM_VERSION = "6";
112   public static final String FILE_SYSTEM_VERSION = "8";
113 
114   // Configuration parameters
115 
116   //TODO: Is having HBase homed on port 60k OK?
117 
118   /** Cluster is in distributed mode or not */
119   public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";
120 
121   /** Config for pluggable load balancers */
122   public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";
123 
124   /** Cluster is standalone or pseudo-distributed */
125   public static final boolean CLUSTER_IS_LOCAL = false;
126 
127   /** Cluster is fully-distributed */
128   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
129 
130   /** Default value for cluster distributed mode */
131   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
132 
133   /** default host address */
134   public static final String DEFAULT_HOST = "0.0.0.0";
135 
136   /** Parameter name for port master listens on. */
137   public static final String MASTER_PORT = "hbase.master.port";
138 
139   /** default port that the master listens on */
140   public static final int DEFAULT_MASTER_PORT = 60000;
141 
142   /** default port for master web api */
143   public static final int DEFAULT_MASTER_INFOPORT = 60010;
144 
145   /** Configuration key for master web API port */
146   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
147 
148   /** Parameter name for the master type being backup (waits for primary to go inactive). */
149   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
150 
151   /** by default every master is a possible primary master unless the conf explicitly overrides it */
152   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
153 
154   /** Name of ZooKeeper quorum configuration parameter. */
155   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
156 
157   /** Name of ZooKeeper config file in conf/ directory. */
158   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
159 
160   /** Common prefix of ZooKeeper configuration properties */
161   public static final String ZK_CFG_PROPERTY_PREFIX =
162       "hbase.zookeeper.property.";
163 
164   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
165       ZK_CFG_PROPERTY_PREFIX.length();
166 
167   /**
168    * The ZK client port key in the ZK properties map. The name reflects the
169    * fact that this is not an HBase configuration key.
170    */
171   public static final String CLIENT_PORT_STR = "clientPort";
172 
173   /** Parameter name for the client port that the zookeeper listens on */
174   public static final String ZOOKEEPER_CLIENT_PORT =
175       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
176 
177   /** Default client port that the zookeeper listens on */
178   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
179 
180   /** Parameter name for the wait time for the recoverable zookeeper */
181   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";
182 
183   /** Default wait time for the recoverable zookeeper */
184   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
185 
186   /** Parameter name for the root dir in ZK for this cluster */
187   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
188 
189   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
190 
191   /**
192    * Parameter name for the limit on concurrent client-side zookeeper
193    * connections
194    */
195   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
196       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
197 
198   /** Parameter name for the ZK data directory */
199   public static final String ZOOKEEPER_DATA_DIR =
200       ZK_CFG_PROPERTY_PREFIX + "dataDir";
201 
202   /** Default limit on concurrent client-side zookeeper connections */
203   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
204 
205   /** Configuration key for ZooKeeper session timeout */
206   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
207 
208   /** Default value for ZooKeeper session timeout */
209   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
210 
211   /** Configuration key for whether to use ZK.multi */
212   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
213 
214   /** Parameter name for port region server listens on. */
215   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
216 
217   /** Default port region server listens on. */
218   public static final int DEFAULT_REGIONSERVER_PORT = 60020;
219 
220   /** default port for region server web api */
221   public static final int DEFAULT_REGIONSERVER_INFOPORT = 60030;
222 
223   /** A configuration key for regionserver info port */
224   public static final String REGIONSERVER_INFO_PORT =
225     "hbase.regionserver.info.port";
226 
227   /** A flag that enables automatic selection of regionserver info port */
228   public static final String REGIONSERVER_INFO_PORT_AUTO =
229       REGIONSERVER_INFO_PORT + ".auto";
230 
231   /** Parameter name for what region server implementation to use. */
232   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
233 
234   /** Parameter name for what master implementation to use. */
235   public static final String MASTER_IMPL= "hbase.master.impl";
236 
237   /** Parameter name for what hbase client implementation to use. */
238   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
239 
240   /** Parameter name for how often threads should wake up */
241   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
242 
243   /** Default value for thread wake frequency */
244   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
245 
246   /** Parameter name for how often we should try to write a version file, before failing */
247   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
248 
249   /** Parameter name for how often we should try to write a version file, before failing */
250   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
251 
252   /** Parameter name for how often a region should should perform a major compaction */
253   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
254 
255   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
256   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
257 
258   /** Parameter name for HBase instance root directory */
259   public static final String HBASE_DIR = "hbase.rootdir";
260 
261   /** Parameter name for HBase client IPC pool type */
262   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
263 
264   /** Parameter name for HBase client IPC pool size */
265   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
266 
267   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
268   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
269 
270   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
271   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
272     "hbase.client.meta.operation.timeout";
273 
274   /** Default HBase client operation timeout, which is tantamount to a blocking call */
275   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = Integer.MAX_VALUE;
276 
277   /** Used to construct the name of the log directory for a region server */
278   public static final String HREGION_LOGDIR_NAME = "WALs";
279 
280   /** Used to construct the name of the splitlog directory for a region server */
281   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
282 
283   /** Like the previous, but for old logs that are about to be deleted */
284   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
285 
286   public static final String CORRUPT_DIR_NAME = "corrupt";
287 
288   /** Used by HBCK to sideline backup data */
289   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
290 
291   /** Any artifacts left from migration can be moved here */
292   public static final String MIGRATION_NAME = ".migration";
293 
294   /** Used to construct the name of the compaction directory during compaction */
295   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
296 
297   /** Conf key for the max file size after which we split the region */
298   public static final String HREGION_MAX_FILESIZE =
299       "hbase.hregion.max.filesize";
300 
301   /** Default maximum file size */
302   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
303 
304   /**
305    * The max number of threads used for opening and closing stores or store
306    * files in parallel
307    */
308   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
309     "hbase.hstore.open.and.close.threads.max";
310 
311   /**
312    * The default number for the max number of threads used for opening and
313    * closing stores or store files in parallel
314    */
315   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
316 
317 
318   /** Conf key for the memstore size at which we flush the memstore */
319   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
320       "hbase.hregion.memstore.flush.size";
321 
322   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
323       "hbase.hregion.edits.replay.skip.errors";
324 
325   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
326       false;
327 
328   /** Maximum value length, enforced on KeyValue construction */
329   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
330 
331   /** name of the file for unique cluster ID */
332   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
333 
334   /** Default value for cluster ID */
335   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
336 
337   // Always store the location of the root table's HRegion.
338   // This HRegion is never split.
339 
340   // region name = table + startkey + regionid. This is the row key.
341   // each row in the root and meta tables describes exactly 1 region
342   // Do we ever need to know all the information that we are storing?
343 
344   // Note that the name of the root table starts with "-" and the name of the
345   // meta table starts with "." Why? it's a trick. It turns out that when we
346   // store region names in memory, we use a SortedMap. Since "-" sorts before
347   // "." (and since no other table name can start with either of these
348   // characters, the root region will always be the first entry in such a Map,
349   // followed by all the meta regions (which will be ordered by their starting
350   // row key as well), followed by all user tables. So when the Master is
351   // choosing regions to assign, it will always choose the root region first,
352   // followed by the meta regions, followed by user regions. Since the root
353   // and meta regions always need to be on-line, this ensures that they will
354   // be the first to be reassigned if the server(s) they are being served by
355   // should go down.
356 
357   public static final String BASE_NAMESPACE_DIR = "data";
358 
359   /** delimiter used between portions of a region name */
360   public static final int META_ROW_DELIMITER = ',';
361 
362   /** The catalog family as a string*/
363   public static final String CATALOG_FAMILY_STR = "info";
364 
365   /** The catalog family */
366   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
367 
368   /** The RegionInfo qualifier as a string */
369   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
370 
371   /** The regioninfo column qualifier */
372   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
373 
374   /** The server column qualifier */
375   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes("server");
376 
377   /** The startcode column qualifier */
378   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes("serverstartcode");
379 
380   /** The open seqnum column qualifier */
381   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes("seqnumDuringOpen");
382 
383   /** The lower-half split region column qualifier */
384   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
385 
386   /** The upper-half split region column qualifier */
387   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
388 
389   /** The lower-half merge region column qualifier */
390   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
391 
392   /** The upper-half merge region column qualifier */
393   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
394 
395   /**
396    * The meta table version column qualifier.
397    * We keep current version of the meta table in this column in <code>-ROOT-</code>
398    * table: i.e. in the 'info:v' column.
399    */
400   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
401 
402   /**
403    * The current version of the meta table.
404    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
405    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
406    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
407    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
408    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
409    * byte[] serialization from Writables to Protobuf.
410    * See HRegionInfo.VERSION
411    */
412   public static final short META_VERSION = 1;
413 
414   // Other constants
415 
416   /**
417    * An empty instance.
418    */
419   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
420 
421   /**
422    * Used by scanners, etc when they want to start at the beginning of a region
423    */
424   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
425 
426   /**
427    * Last row in a table.
428    */
429   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
430 
431   /**
432     * Used by scanners and others when they're trying to detect the end of a
433     * table
434     */
435   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
436 
437   /**
438    * Max length a row can have because of the limitation in TFile.
439    */
440   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
441 
442   /**
443    * Timestamp to use when we want to refer to the latest cell.
444    * This is the timestamp sent by clients when no timestamp is specified on
445    * commit.
446    */
447   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
448 
449   /**
450    * Timestamp to use when we want to refer to the oldest cell.
451    */
452   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
453 
454   /**
455    * LATEST_TIMESTAMP in bytes form
456    */
457   public static final byte [] LATEST_TIMESTAMP_BYTES = {
458     // big-endian
459     (byte) (LATEST_TIMESTAMP >>> 56),
460     (byte) (LATEST_TIMESTAMP >>> 48),
461     (byte) (LATEST_TIMESTAMP >>> 40),
462     (byte) (LATEST_TIMESTAMP >>> 32),
463     (byte) (LATEST_TIMESTAMP >>> 24),
464     (byte) (LATEST_TIMESTAMP >>> 16),
465     (byte) (LATEST_TIMESTAMP >>> 8),
466     (byte) LATEST_TIMESTAMP,
467   };
468 
469   /**
470    * Define for 'return-all-versions'.
471    */
472   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
473 
474   /**
475    * Unlimited time-to-live.
476    */
477 //  public static final int FOREVER = -1;
478   public static final int FOREVER = Integer.MAX_VALUE;
479 
480   /**
481    * Seconds in a week
482    */
483   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
484 
485   //TODO: although the following are referenced widely to format strings for
486   //      the shell. They really aren't a part of the public API. It would be
487   //      nice if we could put them somewhere where they did not need to be
488   //      public. They could have package visibility
489   public static final String NAME = "NAME";
490   public static final String VERSIONS = "VERSIONS";
491   public static final String IN_MEMORY = "IN_MEMORY";
492   public static final String METADATA = "METADATA";
493   public static final String CONFIGURATION = "CONFIGURATION";
494 
495   /**
496    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
497    * run out of array items.  Retries beyond this use the last number in the array.  So, for
498    * example, if hbase.client.pause is 1 second, and maximum retries count
499    * hbase.client.retries.number is 10, we will retry at the following intervals:
500    * 1, 2, 3, 10, 100, 100, 100, 100, 100, 100.
501    */
502   public static int RETRY_BACKOFF[] = { 1, 2, 3, 5, 10, 100 };
503 
504   public static final String REGION_IMPL = "hbase.hregion.impl";
505 
506   /** modifyTable op for replacing the table descriptor */
507   public static enum Modify {
508     CLOSE_REGION,
509     TABLE_COMPACT,
510     TABLE_FLUSH,
511     TABLE_MAJOR_COMPACT,
512     TABLE_SET_HTD,
513     TABLE_SPLIT
514   }
515 
516   /**
517    * Scope tag for locally scoped data.
518    * This data will not be replicated.
519    */
520   public static final int REPLICATION_SCOPE_LOCAL = 0;
521 
522   /**
523    * Scope tag for globally scoped data.
524    * This data will be replicated to all peers.
525    */
526   public static final int REPLICATION_SCOPE_GLOBAL = 1;
527 
528   /**
529    * Default cluster ID, cannot be used to identify a cluster so a key with
530    * this value means it wasn't meant for replication.
531    */
532   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
533 
534     /**
535      * Parameter name for maximum number of bytes returned when calling a
536      * scanner's next method.
537      */
538   public static String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY = "hbase.client.scanner.max.result.size";
539 
540   /**
541    * Maximum number of bytes returned when calling a scanner's next method.
542    * Note that when a single row is larger than this limit the row is still
543    * returned completely.
544    *
545    * The default value is unlimited.
546    */
547   public static long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = Long.MAX_VALUE;
548 
549   /**
550    * Parameter name for client pause value, used mostly as value to wait
551    * before running a retry of a failed get, region lookup, etc.
552    */
553   public static String HBASE_CLIENT_PAUSE = "hbase.client.pause";
554 
555   /**
556    * Default value of {@link #HBASE_CLIENT_PAUSE}.
557    */
558   public static long DEFAULT_HBASE_CLIENT_PAUSE = 1000;
559 
560   /**
561    * Parameter name for server pause value, used mostly as value to wait before
562    * running a retry of a failed operation.
563    */
564   public static String HBASE_SERVER_PAUSE = "hbase.server.pause";
565 
566   /**
567    * Default value of {@link #HBASE_SERVER_PAUSE}.
568    */
569   public static int DEFAULT_HBASE_SERVER_PAUSE = 1000;
570 
571   /**
572    * Parameter name for maximum retries, used as maximum for all retryable
573    * operations such as fetching of the root region from root region server,
574    * getting a cell's value, starting a row update, etc.
575    */
576   public static String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
577 
578   /**
579    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
580    */
581   public static int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
582 
583   /**
584    * Parameter name for client prefetch limit, used as the maximum number of regions
585    * info that will be prefetched.
586    */
587   public static String HBASE_CLIENT_PREFETCH_LIMIT = "hbase.client.prefetch.limit";
588 
589   /**
590    * Default value of {@link #HBASE_CLIENT_PREFETCH_LIMIT}.
591    */
592   public static int DEFAULT_HBASE_CLIENT_PREFETCH_LIMIT = 10;
593 
594   /**
595    * Parameter name to set the default scanner caching for all clients.
596    */
597   public static String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
598 
599   /**
600    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
601    */
602   public static int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = 100;
603 
604   /**
605    * Parameter name for number of rows that will be fetched when calling next on
606    * a scanner if it is not served from memory. Higher caching values will
607    * enable faster scanners but will eat up more memory and some calls of next
608    * may take longer and longer times when the cache is empty.
609    */
610   public static String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
611 
612   /**
613    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
614    */
615   public static int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
616 
617   /**
618    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
619    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
620    * for all intents and purposes, are the same except for their instance ids, then they will not be
621    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
622    * even if the instance ids are the same, it could result in non-shared
623    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
624    * differ.
625    */
626   public static String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
627 
628   /**
629    * The client scanner timeout period in milliseconds.
630    */
631   public static String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
632 
633   /**
634    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
635    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
636    */
637   @Deprecated
638   public static String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
639       "hbase.regionserver.lease.period";
640 
641   /**
642    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
643    */
644   public static int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
645 
646   /**
647    * timeout for each RPC
648    */
649   public static String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
650 
651   /**
652    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
653    */
654   public static int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
655 
656   /**
657    * timeout for short operation RPC
658    */
659   public static String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY = "hbase.rpc.shortoperation.timeout";
660 
661   /**
662    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
663    */
664   public static int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
665 
666   /**
667    * Value indicating the server name was saved with no sequence number.
668    */
669   public static final long NO_SEQNUM = -1;
670 
671 
672   /*
673    * cluster replication constants.
674    */
675   public static final String
676       REPLICATION_ENABLE_KEY = "hbase.replication";
677   public static final String
678       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
679   public static final String
680       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
681   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
682     "org.apache.hadoop.hbase.replication.regionserver.Replication";
683 
684   /** HBCK special code name used as server name when manipulating ZK nodes */
685   public static final String HBCK_CODE_NAME = "HBCKServerName";
686 
687   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
688     "hbase.regionserver.hostname.seen.by.master";
689 
690   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
691       "hbase.master.logcleaner.plugins";
692 
693   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
694     "hbase.regionserver.region.split.policy";
695 
696   /**
697    * Configuration key for the size of the block cache
698    */
699   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
700     "hfile.block.cache.size";
701 
702   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.25f;
703 
704   /*
705     * Minimum percentage of free heap necessary for a successful cluster startup.
706     */
707   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
708 
709   public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile
710       ("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
711   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
712       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
713 
714   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
715   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
716   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
717       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
718       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
719 
720   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
721   public static final int SOCKET_RETRY_WAIT_MS = 200;
722 
723   /** Host name of the local machine */
724   public static final String LOCALHOST = "localhost";
725 
726   /**
727    * If this parameter is set to true, then hbase will read
728    * data and then verify checksums. Checksum verification
729    * inside hdfs will be switched off.  However, if the hbase-checksum
730    * verification fails, then it will switch back to using
731    * hdfs checksums for verifiying data that is being read from storage.
732    *
733    * If this parameter is set to false, then hbase will not
734    * verify any checksums, instead it will depend on checksum verification
735    * being done in the hdfs client.
736    */
737   public static final String HBASE_CHECKSUM_VERIFICATION =
738       "hbase.regionserver.checksum.verify";
739 
740   public static final String LOCALHOST_IP = "127.0.0.1";
741 
742   /** Conf key that enables unflushed WAL edits directly being replayed to region servers */
743   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
744   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = false;
745   public static final String DISALLOW_WRITES_IN_RECOVERING =
746       "hbase.regionserver.disallow.writes.when.recovering";
747   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
748 
749   /** Conf key that specifies timeout value to wait for a region ready */
750   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
751       "hbase.master.log.replay.wait.region.timeout";
752 
753   /**
754    * The name of the configuration parameter that specifies
755    * the number of bytes in a newly created checksum chunk.
756    */
757   public static final String BYTES_PER_CHECKSUM =
758       "hbase.hstore.bytes.per.checksum";
759 
760   /**
761    * The name of the configuration parameter that specifies
762    * the name of an algorithm that is used to compute checksums
763    * for newly created blocks.
764    */
765   public static final String CHECKSUM_TYPE_NAME =
766       "hbase.hstore.checksum.algorithm";
767 
768   /** Enable file permission modification from standard hbase */
769   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
770   /** File permission umask to use when creating hbase data files */
771   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
772 
773   /** Configuration name of HLog Compression */
774   public static final String ENABLE_WAL_COMPRESSION =
775     "hbase.regionserver.wal.enablecompression";
776 
777   /** Region in Transition metrics threshold time */
778   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
779 
780   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
781 
782   /**
783    * The byte array represents for NO_NEXT_INDEXED_KEY;
784    * The actual value is irrelevant because this is always compared by reference.
785    */
786   public static final byte [] NO_NEXT_INDEXED_KEY = Bytes.toBytes("NO_NEXT_INDEXED_KEY");
787   /** delimiter used between portions of a region name */
788   public static final int DELIMITER = ',';
789   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
790       "hbase.config.read.zookeeper.config";
791   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
792       false;
793 
794   /**
795    * QOS attributes: these attributes are used to demarcate RPC call processing
796    * by different set of handlers. For example, HIGH_QOS tagged methods are
797    * handled by high priority handlers.
798    */
799   public static final int NORMAL_QOS = 0;
800   public static final int QOS_THRESHOLD = 10;
801   public static final int HIGH_QOS = 100;
802   public static final int REPLICATION_QOS = 5; // normal_QOS < replication_QOS < high_QOS
803   public static final int REPLAY_QOS = 6; // REPLICATION_QOS < REPLAY_QOS < high_QOS
804 
805   /** Directory under /hbase where archived hfiles are stored */
806   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
807 
808   /**
809    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
810    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
811    * uni-directional.
812    */
813   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
814 
815   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
816   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
817 
818   /** Temporary directory used for table creation and deletion */
819   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
820 
821   /** Directories that are not HBase table directories */
822   public static final List<String> HBASE_NON_TABLE_DIRS =
823     Collections.unmodifiableList(Arrays.asList(new String[] { HREGION_LOGDIR_NAME,
824       HREGION_OLDLOGDIR_NAME, CORRUPT_DIR_NAME, SPLIT_LOGDIR_NAME,
825       HBCK_SIDELINEDIR_NAME, HFILE_ARCHIVE_DIRECTORY, SNAPSHOT_DIR_NAME, HBASE_TEMP_DIRECTORY,
826       OLD_SNAPSHOT_DIR_NAME, BASE_NAMESPACE_DIR, MIGRATION_NAME}));
827 
828   /** Directories that are not HBase user table directories */
829   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
830     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
831       new String[] { TableName.META_TABLE_NAME.getNameAsString(), TableName.ROOT_TABLE_NAME.getNameAsString() },
832       HBASE_NON_TABLE_DIRS.toArray())));
833 
834   /** Health script related settings. */
835   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
836   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
837   public static final String HEALTH_CHORE_WAKE_FREQ =
838       "hbase.node.health.script.frequency";
839   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
840   /**
841    * The maximum number of health check failures a server can encounter consecutively.
842    */
843   public static final String HEALTH_FAILURE_THRESHOLD =
844       "hbase.node.health.failure.threshold";
845   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
846 
847 
848   /**
849    * IP to use for the multicast status messages between the master and the clients.
850    * The default address is chosen as one among others within the ones suitable for multicast
851    * messages.
852    */
853   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
854   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
855 
856   /**
857    * The port to use for the multicast messages.
858    */
859   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.port";
860   public static final int DEFAULT_STATUS_MULTICAST_PORT = 60100;
861 
862 
863 
864   private HConstants() {
865     // Can't be instantiated with this ctor.
866   }
867 }