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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.charset.Charset;
23  import java.util.Arrays;
24  import java.util.Collections;
25  import java.util.List;
26  import java.util.UUID;
27  import java.util.regex.Pattern;
28  
29  import org.apache.commons.lang.ArrayUtils;
30  import org.apache.hadoop.hbase.classification.InterfaceAudience;
31  import org.apache.hadoop.hbase.classification.InterfaceStability;
32  import org.apache.hadoop.hbase.util.Bytes;
33  
34  /**
35   * HConstants holds a bunch of HBase-related constants
36   */
37  @InterfaceAudience.Public
38  @InterfaceStability.Stable
39  public final class HConstants {
40    // NOTICE!!!! Please do not add a constants here, unless they are referenced by a lot of classes.
41  
42    //Bytes.UTF8_ENCODING should be updated if this changed
43    /** When we encode strings, we always specify UTF8 encoding */
44    public static final String UTF8_ENCODING = "UTF-8";
45  
46    //Bytes.UTF8_CHARSET should be updated if this changed
47    /** When we encode strings, we always specify UTF8 encoding */
48    public static final Charset UTF8_CHARSET = Charset.forName(UTF8_ENCODING);
49    /**
50     * Default block size for an HFile.
51     */
52    public final static int DEFAULT_BLOCKSIZE = 64 * 1024;
53  
54    /** Used as a magic return value while optimized index key feature enabled(HBASE-7845) */
55    public final static int INDEX_KEY_MAGIC = -2;
56    /*
57       * Name of directory that holds recovered edits written by the wal log
58       * splitting code, one per region
59       */
60    public static final String RECOVERED_EDITS_DIR = "recovered.edits";
61    /**
62     * The first four bytes of Hadoop RPC connections
63     */
64    public static final byte[] RPC_HEADER = new byte[] { 'H', 'B', 'a', 's' };
65    public static final byte RPC_CURRENT_VERSION = 0;
66  
67    // HFileBlock constants. TODO!!!! THESE DEFINES BELONG IN HFILEBLOCK, NOT UP HERE.
68    // Needed down in hbase-common though by encoders but these encoders should not be dealing
69    // in the internals of hfileblocks. Fix encapsulation.
70  
71    /** The size data structures with minor version is 0 */
72    public static final int HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM = MAGIC_LENGTH + 2 * Bytes.SIZEOF_INT
73        + Bytes.SIZEOF_LONG;
74    /** The size of a version 2 HFile block header, minor version 1.
75     * There is a 1 byte checksum type, followed by a 4 byte bytesPerChecksum
76     * followed by another 4 byte value to store sizeofDataOnDisk.
77     */
78    public static final int HFILEBLOCK_HEADER_SIZE = HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM +
79      Bytes.SIZEOF_BYTE + 2 * Bytes.SIZEOF_INT;
80    /** Just an array of bytes of the right size. */
81    public static final byte[] HFILEBLOCK_DUMMY_HEADER = new byte[HFILEBLOCK_HEADER_SIZE];
82    public static final String REGISTRY_IMPL_CONF_KEY = "hbase.client.registry.impl";
83  
84    //End HFileBlockConstants.
85  
86    /**
87     * Status codes used for return values of bulk operations.
88     */
89    @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
90    public enum OperationStatusCode {
91      NOT_RUN,
92      SUCCESS,
93      BAD_FAMILY,
94      SANITY_CHECK_FAILURE,
95      FAILURE;
96    }
97  
98    /** long constant for zero */
99    public static final Long ZERO_L = Long.valueOf(0L);
100   public static final String NINES = "99999999999999";
101   public static final String ZEROES = "00000000000000";
102 
103   // For migration
104 
105   /** name of version file */
106   public static final String VERSION_FILE_NAME = "hbase.version";
107 
108   /**
109    * Current version of file system.
110    * Version 4 supports only one kind of bloom filter.
111    * Version 5 changes versions in catalog table regions.
112    * Version 6 enables blockcaching on catalog tables.
113    * Version 7 introduces hfile -- hbase 0.19 to 0.20..
114    * Version 8 introduces namespace
115    */
116   // public static final String FILE_SYSTEM_VERSION = "6";
117   public static final String FILE_SYSTEM_VERSION = "8";
118 
119   // Configuration parameters
120 
121   //TODO: Is having HBase homed on port 60k OK?
122 
123   /** Cluster is in distributed mode or not */
124   public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";
125 
126   /** Config for pluggable load balancers */
127   public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";
128 
129   /** Config for balancing the cluster by table */
130   public static final String HBASE_MASTER_LOADBALANCE_BYTABLE = "hbase.master.loadbalance.bytable";
131 
132   /** Config for the max percent of regions in transition */
133   public static final String HBASE_MASTER_BALANCER_MAX_RIT_PERCENT =
134       "hbase.master.balancer.maxRitPercent";
135 
136   /** Default value for the max percent of regions in transition */
137   public static final double DEFAULT_HBASE_MASTER_BALANCER_MAX_RIT_PERCENT = 1.0;
138 
139   /** Config for the max balancing time */
140   public static final String HBASE_BALANCER_MAX_BALANCING = "hbase.balancer.max.balancing";
141 
142   /** Config for the balancer period */
143   public static final String HBASE_BALANCER_PERIOD = "hbase.balancer.period";
144 
145   /** Default value for the balancer period */
146   public static final int DEFAULT_HBASE_BALANCER_PERIOD = 300000;
147 
148   /** The name of the ensemble table */
149   public static final String ENSEMBLE_TABLE_NAME = "hbase:ensemble";
150 
151   /** Config for pluggable region normalizer */
152   public static final String HBASE_MASTER_NORMALIZER_CLASS =
153     "hbase.master.normalizer.class";
154 
155   /** Cluster is standalone or pseudo-distributed */
156   public static final boolean CLUSTER_IS_LOCAL = false;
157 
158   /** Cluster is fully-distributed */
159   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
160 
161   /** Default value for cluster distributed mode */
162   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
163 
164   /** default host address */
165   public static final String DEFAULT_HOST = "0.0.0.0";
166 
167   /** Parameter name for port master listens on. */
168   public static final String MASTER_PORT = "hbase.master.port";
169 
170   /** default port that the master listens on */
171   public static final int DEFAULT_MASTER_PORT = 16000;
172 
173   /** default port for master web api */
174   public static final int DEFAULT_MASTER_INFOPORT = 16010;
175 
176   /** Configuration key for master web API port */
177   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
178 
179   /** Configuration key for the list of master host:ports **/
180   public static final String MASTER_ADDRS_KEY = "hbase.masters";
181 
182   public static final String MASTER_ADDRS_DEFAULT =  "localhost:" + DEFAULT_MASTER_PORT;
183 
184   /** Parameter name for the master type being backup (waits for primary to go inactive). */
185   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
186 
187   /** by default every master is a possible primary master unless the conf explicitly overrides it */
188   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
189 
190   /** Name of ZooKeeper quorum configuration parameter. */
191   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
192 
193   /** Name of ZooKeeper config file in conf/ directory. */
194   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
195 
196   /** Common prefix of ZooKeeper configuration properties */
197   public static final String ZK_CFG_PROPERTY_PREFIX =
198       "hbase.zookeeper.property.";
199 
200   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
201       ZK_CFG_PROPERTY_PREFIX.length();
202 
203   /**
204    * The ZK client port key in the ZK properties map. The name reflects the
205    * fact that this is not an HBase configuration key.
206    */
207   public static final String CLIENT_PORT_STR = "clientPort";
208 
209   /** Parameter name for the client port that the zookeeper listens on */
210   public static final String ZOOKEEPER_CLIENT_PORT =
211       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
212 
213   /** Default client port that the zookeeper listens on */
214   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
215 
216   /** Parameter name for the wait time for the recoverable zookeeper */
217   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";
218 
219   /** Default wait time for the recoverable zookeeper */
220   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
221 
222   /** Parameter name for the root dir in ZK for this cluster */
223   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
224 
225   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
226 
227   /**
228    * Parameter name for the limit on concurrent client-side zookeeper
229    * connections
230    */
231   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
232       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
233 
234   /** Parameter name for the ZK data directory */
235   public static final String ZOOKEEPER_DATA_DIR =
236       ZK_CFG_PROPERTY_PREFIX + "dataDir";
237 
238   /** Parameter name for the ZK tick time */
239   public static final String ZOOKEEPER_TICK_TIME =
240       ZK_CFG_PROPERTY_PREFIX + "tickTime";
241 
242   /** Default limit on concurrent client-side zookeeper connections */
243   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
244 
245   /** Configuration key for ZooKeeper session timeout */
246   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
247 
248   /** Timeout for the ZK sync() call */
249   public static final String ZK_SYNC_BLOCKING_TIMEOUT_MS = "hbase.zookeeper.sync.timeout.millis";
250   // Choice of the default value is based on the following ZK recommendation (from docs). Keeping it
251   // lower lets the callers fail fast in case of any issues.
252   // "The clients view of the system is guaranteed to be up-to-date within a certain time bound.
253   // (On the order of tens of seconds.) Either system changes will be seen by a client within this
254   // bound, or the client will detect a service outage."
255   public static final long ZK_SYNC_BLOCKING_TIMEOUT_DEFAULT_MS = 30 * 1000;
256 
257   /** Default value for ZooKeeper session timeout */
258   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
259 
260   /** Configuration key for whether to use ZK.multi */
261   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
262 
263   /** Parameter name for port region server listens on. */
264   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
265 
266   /** Default port region server listens on. */
267   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
268 
269   /** default port for region server web api */
270   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
271 
272   /** A configuration key for regionserver info port */
273   public static final String REGIONSERVER_INFO_PORT =
274     "hbase.regionserver.info.port";
275 
276   /** A flag that enables automatic selection of regionserver info port */
277   public static final String REGIONSERVER_INFO_PORT_AUTO =
278       REGIONSERVER_INFO_PORT + ".auto";
279 
280   /** Parameter name for what region server implementation to use. */
281   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
282 
283   /** Parameter name for what master implementation to use. */
284   public static final String MASTER_IMPL= "hbase.master.impl";
285 
286   /** Parameter name for what hbase client implementation to use. */
287   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
288 
289   /** Parameter name for how often threads should wake up */
290   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
291 
292   /** Default value for thread wake frequency */
293   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
294 
295   /** Parameter name for how often we should try to write a version file, before failing */
296   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
297 
298   /** Parameter name for how often we should try to write a version file, before failing */
299   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
300 
301   /** Parameter name for how often a region should should perform a major compaction */
302   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
303 
304   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
305   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
306   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
307 
308   /** Parameter name for HBase instance root directory */
309   public static final String HBASE_DIR = "hbase.rootdir";
310 
311   /** Parameter name for HBase client IPC pool type */
312   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
313 
314   /** Parameter name for HBase client IPC pool size */
315   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
316 
317   /** Parameter name for HBase client operation timeout. */
318   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
319 
320   /** Parameter name for HBase client meta operation timeout. */
321   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
322     "hbase.client.meta.operation.timeout";
323 
324   /** Parameter name for HBase client max backoff across SASL relogin failure retries */
325   public static final String HBASE_RELOGIN_MAXBACKOFF = "hbase.security.relogin.maxbackoff";
326 
327   /** Parameter name for HBase client minimum time between forceful relogin attempts */
328   public static final String HBASE_MINTIME_BEFORE_FORCE_RELOGIN =
329       "hbase.mintime.before.force.relogin";
330 
331   /**
332    * Whether forceful relogin (explicit clearing of kerberos tickets) is enabled on SASL
333    * Authentication failure
334    */
335   public static final String HBASE_FORCE_RELOGIN_ENABLED = "hbase.security.force.relogin.enabled";
336 
337   /** Default HBase client operation timeout, which is tantamount to a blocking call */
338   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = 1200000;
339 
340   /** Parameter name for HBase client meta replica scan call timeout. */
341   public static final String HBASE_CLIENT_META_REPLICA_SCAN_TIMEOUT =
342       "hbase.client.meta.replica.scan.timeout";
343 
344   /** Default HBase client meta replica scan call timeout, 1 second */
345   public static final int HBASE_CLIENT_META_REPLICA_SCAN_TIMEOUT_DEFAULT = 1000000;
346 
347 
348   /** Used to construct the name of the log directory for a region server */
349   public static final String HREGION_LOGDIR_NAME = "WALs";
350 
351   /** Used to construct the name of the splitlog directory for a region server */
352   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
353 
354   /** Like the previous, but for old logs that are about to be deleted */
355   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
356 
357   public static final String CORRUPT_DIR_NAME = "corrupt";
358 
359   /** Used by HBCK to sideline backup data */
360   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
361 
362   /** Any artifacts left from migration can be moved here */
363   public static final String MIGRATION_NAME = ".migration";
364 
365   /**
366    * The directory from which co-processor/custom filter jars can be loaded
367    * dynamically by the region servers. This value can be overridden by the
368    * hbase.dynamic.jars.dir config.
369    */
370   public static final String LIB_DIR = "lib";
371 
372   /** Used to construct the name of the compaction directory during compaction */
373   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
374 
375   /** Conf key for the max file size after which we split the region */
376   public static final String HREGION_MAX_FILESIZE =
377       "hbase.hregion.max.filesize";
378 
379   /** Default maximum file size */
380   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
381 
382   /**
383    * Max size of single row for Get's or Scan's without in-row scanning flag set.
384    */
385   public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
386 
387   /**
388    * Default max row size (1 Gb).
389    */
390   public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
391 
392   /**
393    * The max number of threads used for opening and closing stores or store
394    * files in parallel
395    */
396   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
397     "hbase.hstore.open.and.close.threads.max";
398 
399   /**
400    * The default number for the max number of threads used for opening and
401    * closing stores or store files in parallel
402    */
403   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
404 
405   /**
406    * Block updates if memstore has hbase.hregion.memstore.block.multiplier
407    * times hbase.hregion.memstore.flush.size bytes.  Useful preventing
408    * runaway memstore during spikes in update traffic.
409    */
410   public static final String HREGION_MEMSTORE_BLOCK_MULTIPLIER =
411           "hbase.hregion.memstore.block.multiplier";
412 
413   /**
414    * Default value for hbase.hregion.memstore.block.multiplier
415    */
416   public static final int DEFAULT_HREGION_MEMSTORE_BLOCK_MULTIPLIER = 4;
417 
418   /** Conf key for the memstore size at which we flush the memstore */
419   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
420       "hbase.hregion.memstore.flush.size";
421 
422   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
423       "hbase.hregion.edits.replay.skip.errors";
424 
425   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
426       false;
427 
428   /** Maximum value length, enforced on KeyValue construction */
429   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
430 
431   /** name of the file for unique cluster ID */
432   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
433 
434   /** Default value for cluster ID */
435   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
436 
437   /** Parameter name for # days to keep MVCC values during a major compaction */
438   public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
439   /** At least to keep MVCC values in hfiles for 5 days */
440   public static final int MIN_KEEP_SEQID_PERIOD = 5;
441 
442   // Always store the location of the root table's HRegion.
443   // This HRegion is never split.
444 
445   // region name = table + startkey + regionid. This is the row key.
446   // each row in the root and meta tables describes exactly 1 region
447   // Do we ever need to know all the information that we are storing?
448 
449   // Note that the name of the root table starts with "-" and the name of the
450   // meta table starts with "." Why? it's a trick. It turns out that when we
451   // store region names in memory, we use a SortedMap. Since "-" sorts before
452   // "." (and since no other table name can start with either of these
453   // characters, the root region will always be the first entry in such a Map,
454   // followed by all the meta regions (which will be ordered by their starting
455   // row key as well), followed by all user tables. So when the Master is
456   // choosing regions to assign, it will always choose the root region first,
457   // followed by the meta regions, followed by user regions. Since the root
458   // and meta regions always need to be on-line, this ensures that they will
459   // be the first to be reassigned if the server(s) they are being served by
460   // should go down.
461 
462 
463   /**
464    * The hbase:meta table's name.
465    * @deprecated For upgrades of 0.94 to 0.96
466    */
467   @Deprecated  // for compat from 0.94 -> 0.96.
468   public static final byte[] META_TABLE_NAME = TableName.META_TABLE_NAME.getName();
469 
470   public static final String BASE_NAMESPACE_DIR = "data";
471 
472   /** delimiter used between portions of a region name */
473   public static final int META_ROW_DELIMITER = ',';
474 
475   /** The catalog family as a string*/
476   public static final String CATALOG_FAMILY_STR = "info";
477 
478   /** The catalog family */
479   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
480 
481   /** The RegionInfo qualifier as a string */
482   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
483 
484   /** The regioninfo column qualifier */
485   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
486 
487   /** The server column qualifier */
488   public static final String SERVER_QUALIFIER_STR = "server";
489   /** The server column qualifier */
490   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes(SERVER_QUALIFIER_STR);
491 
492   /** The startcode column qualifier */
493   public static final String STARTCODE_QUALIFIER_STR = "serverstartcode";
494   /** The startcode column qualifier */
495   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes(STARTCODE_QUALIFIER_STR);
496 
497   /** The open seqnum column qualifier */
498   public static final String SEQNUM_QUALIFIER_STR = "seqnumDuringOpen";
499   /** The open seqnum column qualifier */
500   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes(SEQNUM_QUALIFIER_STR);
501 
502   /** The state column qualifier */
503   public static final String STATE_QUALIFIER_STR = "state";
504 
505   public static final byte [] STATE_QUALIFIER = Bytes.toBytes(STATE_QUALIFIER_STR);
506 
507   /**
508    * The serverName column qualifier. Its the server where the region is
509    * transitioning on, while column server is the server where the region is
510    * opened on. They are the same when the region is in state OPEN.
511    */
512   public static final String SERVERNAME_QUALIFIER_STR = "sn";
513 
514   public static final byte [] SERVERNAME_QUALIFIER = Bytes.toBytes(SERVERNAME_QUALIFIER_STR);
515 
516   /** The lower-half split region column qualifier */
517   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
518 
519   /** The upper-half split region column qualifier */
520   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
521 
522   /** The lower-half merge region column qualifier */
523   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
524 
525   /** The upper-half merge region column qualifier */
526   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
527 
528   /**
529    * The meta table version column qualifier.
530    * We keep current version of the meta table in this column in <code>-ROOT-</code>
531    * table: i.e. in the 'info:v' column.
532    */
533   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
534 
535   /**
536    * The current version of the meta table.
537    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
538    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
539    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
540    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
541    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
542    * byte[] serialization from Writables to Protobuf.
543    * See HRegionInfo.VERSION
544    */
545   public static final short META_VERSION = 1;
546 
547   // Other constants
548 
549   /**
550    * An empty instance.
551    */
552   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
553 
554   /**
555    * Used by scanners, etc when they want to start at the beginning of a region
556    */
557   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
558 
559   /**
560    * Last row in a table.
561    */
562   public static final byte [] EMPTY_END_ROW = EMPTY_BYTE_ARRAY;
563 
564   /**
565     * Used by scanners and others when they're trying to detect the end of a
566     * table
567     */
568   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
569 
570   /**
571    * Max length a row can have because of the limitation in TFile.
572    */
573   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
574 
575   /**
576    * Timestamp to use when we want to refer to the latest cell.
577    * This is the timestamp sent by clients when no timestamp is specified on
578    * commit.
579    */
580   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
581 
582   /**
583    * Timestamp to use when we want to refer to the oldest cell.
584    * Special! Used in fake Cells only. Should never be the timestamp on an actual Cell returned to
585    * a client.
586    * @deprecated Should not be public since hbase-1.3.0. For internal use only. Move internal to
587    * Scanners flagged as special timestamp value never to be returned as timestamp on a Cell.
588    */
589   @Deprecated
590   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
591 
592   /**
593    * LATEST_TIMESTAMP in bytes form
594    */
595   public static final byte [] LATEST_TIMESTAMP_BYTES = {
596     // big-endian
597     (byte) (LATEST_TIMESTAMP >>> 56),
598     (byte) (LATEST_TIMESTAMP >>> 48),
599     (byte) (LATEST_TIMESTAMP >>> 40),
600     (byte) (LATEST_TIMESTAMP >>> 32),
601     (byte) (LATEST_TIMESTAMP >>> 24),
602     (byte) (LATEST_TIMESTAMP >>> 16),
603     (byte) (LATEST_TIMESTAMP >>> 8),
604     (byte) LATEST_TIMESTAMP,
605   };
606 
607   /**
608    * Define for 'return-all-versions'.
609    */
610   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
611 
612   /**
613    * Unlimited time-to-live.
614    */
615 //  public static final int FOREVER = -1;
616   public static final int FOREVER = Integer.MAX_VALUE;
617 
618   /**
619    * Seconds in a week
620    */
621   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
622 
623   /**
624    * Seconds in a day, hour and minute
625    */
626   public static final int DAY_IN_SECONDS = 24 * 60 * 60;
627   public static final int HOUR_IN_SECONDS = 60 * 60;
628   public static final int MINUTE_IN_SECONDS = 60;
629 
630   //TODO: although the following are referenced widely to format strings for
631   //      the shell. They really aren't a part of the public API. It would be
632   //      nice if we could put them somewhere where they did not need to be
633   //      public. They could have package visibility
634   public static final String NAME = "NAME";
635   public static final String VERSIONS = "VERSIONS";
636   public static final String IN_MEMORY = "IN_MEMORY";
637   public static final String METADATA = "METADATA";
638   public static final String CONFIGURATION = "CONFIGURATION";
639 
640   /**
641    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
642    * run out of array items.  Retries beyond this use the last number in the array.  So, for
643    * example, if hbase.client.pause is 1 second, and maximum retries count
644    * hbase.client.retries.number is 10, we will retry at the following intervals:
645    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
646    * With 100ms, a back-off of 200 means 20s
647    */
648   public static final int [] RETRY_BACKOFF = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
649 
650   public static final String REGION_IMPL = "hbase.hregion.impl";
651 
652   /** modifyTable op for replacing the table descriptor */
653   @InterfaceAudience.Private
654   public static enum Modify {
655     CLOSE_REGION,
656     TABLE_COMPACT,
657     TABLE_FLUSH,
658     TABLE_MAJOR_COMPACT,
659     TABLE_SET_HTD,
660     TABLE_SPLIT
661   }
662 
663   /**
664    * Scope tag for locally scoped data.
665    * This data will not be replicated.
666    */
667   public static final int REPLICATION_SCOPE_LOCAL = 0;
668 
669   /**
670    * Scope tag for globally scoped data.
671    * This data will be replicated to all peers.
672    */
673   public static final int REPLICATION_SCOPE_GLOBAL = 1;
674 
675   /**
676    * Default cluster ID, cannot be used to identify a cluster so a key with
677    * this value means it wasn't meant for replication.
678    */
679   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
680 
681   /**
682    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
683    * Controlled by the client.
684    */
685   public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
686       "hbase.client.scanner.max.result.size";
687 
688   /**
689    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
690    * Controlled by the server.
691    */
692   public static final String HBASE_SERVER_SCANNER_MAX_RESULT_SIZE_KEY =
693       "hbase.server.scanner.max.result.size";
694 
695   /**
696    * Maximum number of bytes returned when calling a scanner's next method.
697    * Note that when a single row is larger than this limit the row is still
698    * returned completely.
699    *
700    * The default value is 2MB.
701    */
702   public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
703 
704   /**
705    * Maximum number of bytes returned when calling a scanner's next method.
706    * Note that when a single row is larger than this limit the row is still
707    * returned completely.
708    * Safety setting to protect the region server.
709    *
710    * The default value is 100MB. (a client would rarely request larger chunks on purpose)
711    */
712   public static final long DEFAULT_HBASE_SERVER_SCANNER_MAX_RESULT_SIZE = 100 * 1024 * 1024;
713 
714   /**
715    * Parameter name for client pause value, used mostly as value to wait
716    * before running a retry of a failed get, region lookup, etc.
717    */
718   public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
719 
720   /**
721    * Default value of {@link #HBASE_CLIENT_PAUSE}.
722    */
723   public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
724 
725   /*
726    * Parameter name for client pause value for special case such as call queue too big, etc.
727    */
728   public static final String HBASE_CLIENT_PAUSE_FOR_CQTBE = "hbase.client.pause.cqtbe";
729 
730   /**
731    * The maximum number of concurrent connections the client will maintain.
732    */
733   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
734 
735   /**
736    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
737    */
738   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
739 
740   /**
741    * The maximum number of concurrent connections the client will maintain to a single
742    * RegionServer.
743    */
744   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
745 
746   /**
747    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
748    */
749   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
750 
751   /**
752    * The maximum number of concurrent connections the client will maintain to a single
753    * Region.
754    */
755   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
756 
757   /**
758    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
759    */
760   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
761 
762   /**
763    * The maximum number of concurrent pending RPC requests for one server in process level.
764    */
765   public static final String HBASE_CLIENT_PERSERVER_REQUESTS_THRESHOLD =
766       "hbase.client.perserver.requests.threshold";
767 
768   /**
769    * Default value of {@link #HBASE_CLIENT_PERSERVER_REQUESTS_THRESHOLD}.
770    */
771   public static final int DEFAULT_HBASE_CLIENT_PERSERVER_REQUESTS_THRESHOLD = Integer.MAX_VALUE;
772 
773 
774   /**
775    * Parameter name for server pause value, used mostly as value to wait before
776    * running a retry of a failed operation.
777    */
778   public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
779 
780   /**
781    * Default value of {@link #HBASE_SERVER_PAUSE}.
782    */
783   public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
784 
785   /**
786    * Parameter name for maximum retries, used as maximum for all retryable
787    * operations such as fetching of the root region from root region server,
788    * getting a cell's value, starting a row update, etc.
789    */
790   public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
791 
792   /**
793    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
794    */
795   public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
796 
797   /**
798    * Parameter name to set the default scanner caching for all clients.
799    */
800   public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
801 
802   /**
803    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
804    */
805   public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = Integer.MAX_VALUE;
806 
807   /**
808    * Parameter name for number of versions, kept by meta table.
809    */
810   public static String HBASE_META_VERSIONS = "hbase.meta.versions";
811 
812   /**
813    * Default value of {@link #HBASE_META_VERSIONS}.
814    */
815   public static int DEFAULT_HBASE_META_VERSIONS = 3;
816 
817   /**
818    * Parameter name for number of versions, kept by meta table.
819    */
820   public static String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
821 
822   /**
823    * Default value of {@link #HBASE_META_BLOCK_SIZE}.
824    */
825   public static int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
826 
827   /**
828    * Parameter name for number of rows that will be fetched when calling next on
829    * a scanner if it is not served from memory. Higher caching values will
830    * enable faster scanners but will eat up more memory and some calls of next
831    * may take longer and longer times when the cache is empty.
832    */
833   public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
834 
835   /**
836    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
837    */
838   public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
839 
840   /**
841    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
842    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
843    * for all intents and purposes, are the same except for their instance ids, then they will not be
844    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
845    * even if the instance ids are the same, it could result in non-shared
846    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
847    * differ.
848    */
849   public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
850 
851   /**
852    * The client scanner timeout period in milliseconds.
853    */
854   public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
855 
856   /**
857    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
858    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
859    */
860   @Deprecated
861   public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
862       "hbase.regionserver.lease.period";
863 
864   /**
865    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
866    */
867   public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
868 
869   /**
870    * timeout for each RPC
871    * @deprecated Use {@link #HBASE_RPC_READ_TIMEOUT_KEY} or {@link #HBASE_RPC_WRITE_TIMEOUT_KEY}
872    * instead.
873    */
874   @Deprecated
875   public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
876 
877   /**
878    * timeout for each read RPC
879    */
880   public static final String HBASE_RPC_READ_TIMEOUT_KEY = "hbase.rpc.read.timeout";
881 
882   /**
883    * timeout for each write RPC
884    */
885   public static final String HBASE_RPC_WRITE_TIMEOUT_KEY = "hbase.rpc.write.timeout";
886 
887   /**
888    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
889    */
890   public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
891 
892   /**
893    * timeout for short operation RPC
894    */
895   public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY =
896       "hbase.rpc.shortoperation.timeout";
897 
898   /**
899    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
900    */
901   public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
902 
903   /**
904    * Value indicating the server name was saved with no sequence number.
905    */
906   public static final long NO_SEQNUM = -1;
907 
908 
909   /*
910    * cluster replication constants.
911    */
912   public static final String
913       REPLICATION_ENABLE_KEY = "hbase.replication";
914   public static final boolean
915       REPLICATION_ENABLE_DEFAULT = true;
916   public static final String
917       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
918   public static final String
919       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
920   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
921     "org.apache.hadoop.hbase.replication.regionserver.Replication";
922   public static final String REPLICATION_BULKLOAD_ENABLE_KEY = "hbase.replication.bulkload.enabled";
923   public static final boolean REPLICATION_BULKLOAD_ENABLE_DEFAULT = false;
924   /** Replication cluster id of source cluster which uniquely identifies itself with peer cluster */
925   public static final String REPLICATION_CLUSTER_ID = "hbase.replication.cluster.id";
926   /**
927    * Max total size of buffered entries in all replication peers. It will prevent server getting
928    * OOM if there are many peers. Default value is 256MB which is four times to default
929    * replication.source.size.capacity.
930    */
931   public static final String REPLICATION_SOURCE_TOTAL_BUFFER_KEY = "replication.total.buffer.quota";
932   public static final int REPLICATION_SOURCE_TOTAL_BUFFER_DFAULT = 256 * 1024 * 1024;
933 
934 
935   /**
936    * Directory where the source cluster file system client configuration are placed which is used by
937    * sink cluster to copy HFiles from source cluster file system
938    */
939   public static final String REPLICATION_CONF_DIR = "hbase.replication.conf.dir";
940 
941   /** Maximum time to retry for a failed bulk load request */
942   public static final String BULKLOAD_MAX_RETRIES_NUMBER = "hbase.bulkload.retries.number";
943 
944   /** HBCK special code name used as server name when manipulating ZK nodes */
945   public static final String HBCK_CODE_NAME = "HBCKServerName";
946 
947   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
948     "hbase.regionserver.hostname.seen.by.master";
949 
950   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
951       "hbase.master.logcleaner.plugins";
952 
953   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
954     "hbase.regionserver.region.split.policy";
955 
956   /** Whether nonces are enabled; default is true. */
957   public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
958 
959   /**
960    * Configuration key for the size of the block cache
961    */
962   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
963     "hfile.block.cache.size";
964 
965   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
966 
967   /*
968     * Minimum percentage of free heap necessary for a successful cluster startup.
969     */
970   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
971 
972   public static final Pattern CP_HTD_ATTR_KEY_PATTERN =
973       Pattern.compile("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
974 
975   /**
976    * Pattern that matches a coprocessor specification. Form is:
977    * <code>
978    *&lt;coprocessor jar file location> '|' &lt;class name> ['|' &lt;priority> ['|' &lt;arguments>]]
979    * </code>
980    * ...where arguments are <code>&lt;KEY> '=' &lt;VALUE> [,...]</code>
981    * <p>For example: <code>hdfs:///foo.jar|com.foo.FooRegionObserver|1001|arg1=1,arg2=2</code>
982    */
983   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
984       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
985 
986   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
987   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
988   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
989       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
990       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
991   public static final String CP_HTD_ATTR_INCLUSION_KEY =
992       "hbase.coprocessor.classloader.included.classes";
993 
994   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
995   public static final int SOCKET_RETRY_WAIT_MS = 200;
996 
997   /** Host name of the local machine */
998   public static final String LOCALHOST = "localhost";
999 
1000   /**
1001    * If this parameter is set to true, then hbase will read
1002    * data and then verify checksums. Checksum verification
1003    * inside hdfs will be switched off.  However, if the hbase-checksum
1004    * verification fails, then it will switch back to using
1005    * hdfs checksums for verifiying data that is being read from storage.
1006    *
1007    * If this parameter is set to false, then hbase will not
1008    * verify any checksums, instead it will depend on checksum verification
1009    * being done in the hdfs client.
1010    */
1011   public static final String HBASE_CHECKSUM_VERIFICATION =
1012       "hbase.regionserver.checksum.verify";
1013 
1014   public static final String LOCALHOST_IP = "127.0.0.1";
1015 
1016   /** Conf key that enables unflushed WAL edits directly being replayed to region servers
1017    */
1018   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
1019   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = false;
1020   public static final String DISALLOW_WRITES_IN_RECOVERING =
1021       "hbase.regionserver.disallow.writes.when.recovering";
1022   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
1023 
1024   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
1025   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
1026 
1027   /*
1028    * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
1029    * -1  => Disable aborting
1030    * 0   => Abort if even a single handler has died
1031    * 0.x => Abort only when this percent of handlers have died
1032    * 1   => Abort only all of the handers have died
1033    */
1034   public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
1035       "hbase.regionserver.handler.abort.on.error.percent";
1036   public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
1037 
1038   //High priority handlers to deal with admin requests and system table operation requests
1039   public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
1040       "hbase.regionserver.metahandler.count";
1041   public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 20;
1042 
1043   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
1044       "hbase.regionserver.replication.handler.count";
1045   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
1046 
1047   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
1048   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
1049 
1050   /** Conf key that specifies timeout value to wait for a region ready */
1051   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
1052       "hbase.master.log.replay.wait.region.timeout";
1053 
1054   /** Conf key for enabling meta replication */
1055   public static final String USE_META_REPLICAS = "hbase.meta.replicas.use";
1056   public static final boolean DEFAULT_USE_META_REPLICAS = false;
1057   public static final String META_REPLICAS_NUM = "hbase.meta.replica.count";
1058   public static final int DEFAULT_META_REPLICA_NUM = 1;
1059 
1060   /**
1061    * The name of the configuration parameter that specifies
1062    * the number of bytes in a newly created checksum chunk.
1063    */
1064   public static final String BYTES_PER_CHECKSUM =
1065       "hbase.hstore.bytes.per.checksum";
1066 
1067   /**
1068    * The name of the configuration parameter that specifies
1069    * the name of an algorithm that is used to compute checksums
1070    * for newly created blocks.
1071    */
1072   public static final String CHECKSUM_TYPE_NAME =
1073       "hbase.hstore.checksum.algorithm";
1074 
1075   /** Enable file permission modification from standard hbase */
1076   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
1077   /** File permission umask to use when creating hbase data files */
1078   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
1079 
1080   /** Configuration name of WAL Compression */
1081   public static final String ENABLE_WAL_COMPRESSION =
1082     "hbase.regionserver.wal.enablecompression";
1083 
1084   /** Configuration name of WAL storage policy
1085    * Valid values are: HOT, COLD, WARM, ALL_SSD, ONE_SSD, LAZY_PERSIST
1086    * See http://hadoop.apache.org/docs/r2.7.3/hadoop-project-dist/hadoop-hdfs/ArchivalStorage.html*/
1087   public static final String WAL_STORAGE_POLICY = "hbase.wal.storage.policy";
1088   /**
1089    * "NONE" is not a valid storage policy and means we defer the policy to HDFS. @see
1090    * <a href="https://issues.apache.org/jira/browse/HBASE-20691">HBASE-20691</a>
1091    */
1092   public static final String DEFER_TO_HDFS_STORAGE_POLICY = "NONE";
1093   /** By default we defer the WAL storage policy to HDFS */
1094   public static final String DEFAULT_WAL_STORAGE_POLICY = DEFER_TO_HDFS_STORAGE_POLICY;
1095 
1096   /** Region in Transition metrics threshold time */
1097   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD =
1098       "hbase.metrics.rit.stuck.warning.threshold";
1099 
1100   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
1101 
1102   /** delimiter used between portions of a region name */
1103   public static final int DELIMITER = ',';
1104   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
1105       "hbase.config.read.zookeeper.config";
1106   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
1107       false;
1108 
1109   /**
1110    * QOS attributes: these attributes are used to demarcate RPC call processing
1111    * by different set of handlers. For example, HIGH_QOS tagged methods are
1112    * handled by high priority handlers.
1113    */
1114   // normal_QOS < QOS_threshold < replication_QOS < replay_QOS < admin_QOS < high_QOS
1115   public static final int PRIORITY_UNSET = -1;
1116   public static final int NORMAL_QOS = 0;
1117   public static final int QOS_THRESHOLD = 10;
1118   public static final int HIGH_QOS = 200;
1119   public static final int REPLICATION_QOS = 5;
1120   public static final int REPLAY_QOS = 6;
1121   public static final int ADMIN_QOS = 100;
1122   public static final int SYSTEMTABLE_QOS = HIGH_QOS;
1123 
1124   /** Directory under /hbase where archived hfiles are stored */
1125   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
1126 
1127   /**
1128    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
1129    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
1130    * uni-directional.
1131    */
1132   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
1133 
1134   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
1135   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
1136 
1137   /** Temporary directory used for table creation and deletion */
1138   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
1139   /**
1140    * The period (in milliseconds) between computing region server point in time metrics
1141    */
1142   public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
1143   public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
1144   /** Directories that are not HBase table directories */
1145   public static final List<String> HBASE_NON_TABLE_DIRS =
1146     Collections.unmodifiableList(Arrays.asList(new String[] {
1147       HBCK_SIDELINEDIR_NAME, HBASE_TEMP_DIRECTORY, MIGRATION_NAME
1148     }));
1149 
1150   /** Directories that are not HBase user table directories */
1151   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
1152     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
1153       new String[] { TableName.META_TABLE_NAME.getNameAsString() },
1154       HBASE_NON_TABLE_DIRS.toArray())));
1155 
1156   /** Health script related settings. */
1157   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
1158   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
1159   public static final String HEALTH_CHORE_WAKE_FREQ =
1160       "hbase.node.health.script.frequency";
1161   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
1162   /**
1163    * The maximum number of health check failures a server can encounter consecutively.
1164    */
1165   public static final String HEALTH_FAILURE_THRESHOLD =
1166       "hbase.node.health.failure.threshold";
1167   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
1168 
1169   public static final String EXECUTOR_STATUS_COLLECT_ENABLED =
1170       "hbase.executors.status.collect.enabled";
1171   public static final boolean DEFAULT_EXECUTOR_STATUS_COLLECT_ENABLED = true;
1172 
1173   /**
1174    * Setting to activate, or not, the publication of the status by the master. Default
1175    *  notification is by a multicast message.
1176    */
1177   public static final String STATUS_PUBLISHED = "hbase.status.published";
1178   public static final boolean STATUS_PUBLISHED_DEFAULT = false;
1179 
1180   /**
1181    * IP to use for the multicast status messages between the master and the clients.
1182    * The default address is chosen as one among others within the ones suitable for multicast
1183    * messages.
1184    */
1185   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
1186   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
1187 
1188   /**
1189    * The address to use for binding the local socket for receiving multicast. Defaults to
1190    * 0.0.0.0.
1191    * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
1192    */
1193   public static final String STATUS_MULTICAST_BIND_ADDRESS =
1194       "hbase.status.multicast.bind.address.ip";
1195   public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
1196 
1197   /**
1198    * The port to use for the multicast messages.
1199    */
1200   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
1201   public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
1202 
1203   public static final long NO_NONCE = 0;
1204 
1205   /** Default cipher for encryption */
1206   public static final String CIPHER_AES = "AES";
1207 
1208   /** Configuration key for the crypto algorithm provider, a class name */
1209   public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
1210 
1211   /** Configuration key for the crypto key provider, a class name */
1212   public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
1213 
1214   /** Configuration key for the crypto key provider parameters */
1215   public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
1216       "hbase.crypto.keyprovider.parameters";
1217 
1218   /** Configuration key for the name of the master key for the cluster, a string */
1219   public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
1220 
1221   /** Configuration key for the name of the alternate master key for the cluster, a string */
1222   public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
1223     "hbase.crypto.master.alternate.key.name";
1224 
1225   /** Configuration key for the algorithm to use when encrypting the WAL, a string */
1226   public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
1227 
1228   /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
1229   public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
1230 
1231   /** Configuration key for the algorithm used for creating jks key, a string */
1232   public static final String CRYPTO_KEY_ALGORITHM_CONF_KEY = "hbase.crypto.key.algorithm";
1233 
1234   /** Configuration key for the name of the alternate cipher algorithm for the cluster, a string */
1235   public static final String CRYPTO_ALTERNATE_KEY_ALGORITHM_CONF_KEY =
1236       "hbase.crypto.alternate.key.algorithm";
1237 
1238   /** Configuration key for enabling WAL encryption, a boolean */
1239   public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
1240 
1241   /** Configuration key for setting RPC codec class name */
1242   public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
1243 
1244   /** Configuration key for setting replication codec class name */
1245   public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
1246 
1247   /** Maximum number of threads used by the replication source for shipping edits to the sinks */
1248   public static final String REPLICATION_SOURCE_MAXTHREADS_KEY =
1249       "hbase.replication.source.maxthreads";
1250 
1251   /** Drop edits for tables that been deleted from the replication source and target */
1252   public static final String REPLICATION_DROP_ON_DELETED_TABLE_KEY =
1253       "hbase.replication.drop.on.deleted.table";
1254 
1255   /** Maximum number of threads used by the replication source for shipping edits to the sinks */
1256   public static final int REPLICATION_SOURCE_MAXTHREADS_DEFAULT = 10;
1257 
1258   /** Config for pluggable consensus provider */
1259   public static final String HBASE_COORDINATED_STATE_MANAGER_CLASS =
1260     "hbase.coordinated.state.manager.class";
1261 
1262   /** Configuration key for SplitLog manager timeout */
1263   public static final String HBASE_SPLITLOG_MANAGER_TIMEOUT = "hbase.splitlog.manager.timeout";
1264 
1265   /**
1266    * Configuration keys for Bucket cache
1267    */
1268   // TODO moving these bucket cache implementation specific configs to this level is violation of
1269   // encapsulation. But as these has to be referred from hbase-common and bucket cache
1270   // sits in hbase-server, there were no other go! Can we move the cache implementation to
1271   // hbase-common?
1272 
1273   /**
1274    * Current ioengine options in include: heap, offheap and file:PATH (where PATH is the path
1275    * to the file that will host the file-based cache.  See BucketCache#getIOEngineFromName() for
1276    * list of supported ioengine options.
1277    * <p>Set this option and a non-zero {@link #BUCKET_CACHE_SIZE_KEY} to enable bucket cache.
1278    */
1279   public static final String BUCKET_CACHE_IOENGINE_KEY = "hbase.bucketcache.ioengine";
1280 
1281   /**
1282    * When using bucket cache, this is a float that EITHER represents a percentage of total heap
1283    * memory size to give to the cache (if &lt; 1.0) OR, it is the capacity in
1284    * megabytes of the cache.
1285    */
1286   public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1287 
1288   /**
1289    * HConstants for fast fail on the client side follow
1290    */
1291   /**
1292    * Config for enabling/disabling the fast fail mode.
1293    */
1294   public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1295       "hbase.client.fast.fail.mode.enabled";
1296 
1297   public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT =
1298       false;
1299 
1300   public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1301       "hbase.client.fastfail.threshold";
1302 
1303   public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT =
1304       60000;
1305 
1306   public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1307       "hbase.client.fast.fail.cleanup.duration";
1308 
1309   public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT =
1310       600000;
1311 
1312   public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1313       "hbase.client.fast.fail.interceptor.impl";
1314 
1315   /** Config key for if the server should send backpressure and if the client should listen to
1316    * that backpressure from the server */
1317   public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1318   public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1319 
1320   public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1321       "hbase.heap.occupancy.low_water_mark";
1322   public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1323   public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1324       "hbase.heap.occupancy.high_water_mark";
1325   public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1326 
1327   /**
1328    * The max number of threads used for splitting storefiles in parallel during
1329    * the region split process.
1330    */
1331   public static final String REGION_SPLIT_THREADS_MAX =
1332     "hbase.regionserver.region.split.threads.max";
1333 
1334   /** Canary config keys */
1335   public static final String HBASE_CANARY_WRITE_DATA_TTL_KEY = "hbase.canary.write.data.ttl";
1336 
1337   public static final String HBASE_CANARY_WRITE_PERSERVER_REGIONS_LOWERLIMIT_KEY =
1338       "hbase.canary.write.perserver.regions.lowerLimit";
1339 
1340   public static final String HBASE_CANARY_WRITE_PERSERVER_REGIONS_UPPERLIMIT_KEY =
1341       "hbase.canary.write.perserver.regions.upperLimit";
1342 
1343   public static final String HBASE_CANARY_WRITE_VALUE_SIZE_KEY = "hbase.canary.write.value.size";
1344 
1345   public static final String HBASE_CANARY_WRITE_TABLE_CHECK_PERIOD_KEY =
1346       "hbase.canary.write.table.check.period";
1347   
1348   public static final String HBASE_CANARY_READ_RAW_SCAN_KEY = "hbase.canary.read.raw.enabled";
1349 
1350   /**
1351    * Configuration keys for programmatic JAAS configuration for secured ZK interaction
1352    */
1353   public static final String ZK_CLIENT_KEYTAB_FILE = "hbase.zookeeper.client.keytab.file";
1354   public static final String ZK_CLIENT_KERBEROS_PRINCIPAL =
1355       "hbase.zookeeper.client.kerberos.principal";
1356   public static final String ZK_SERVER_KEYTAB_FILE = "hbase.zookeeper.server.keytab.file";
1357   public static final String ZK_SERVER_KERBEROS_PRINCIPAL =
1358       "hbase.zookeeper.server.kerberos.principal";
1359 
1360   /** Config key for hbase temporary directory in hdfs */
1361   public static final String TEMPORARY_FS_DIRECTORY_KEY = "hbase.fs.tmp.dir";
1362   public static final String DEFAULT_TEMPORARY_HDFS_DIRECTORY = "/user/"
1363       + System.getProperty("user.name") + "/hbase-staging";
1364   public static final String DEFAULT_LOSSY_COUNTING_ERROR_RATE =
1365       "hbase.util.default.lossycounting.errorrate";
1366 
1367   // Default TTL - FOREVER
1368   public static final long DEFAULT_SNAPSHOT_TTL = 0;
1369 
1370   // User defined Default TTL config key
1371   public static final String DEFAULT_SNAPSHOT_TTL_CONFIG_KEY = "hbase.master.snapshot.ttl";
1372 
1373   // Regions Recovery based on high storeFileRefCount threshold value
1374   public static final String STORE_FILE_REF_COUNT_THRESHOLD =
1375     "hbase.regions.recovery.store.file.ref.count";
1376 
1377   // default -1 indicates there is no threshold on high storeRefCount
1378   public static final int DEFAULT_STORE_FILE_REF_COUNT_THRESHOLD = -1;
1379 
1380   public static final String REGIONS_RECOVERY_INTERVAL =
1381     "hbase.master.regions.recovery.check.interval";
1382 
1383   public static final int DEFAULT_REGIONS_RECOVERY_INTERVAL = 1200 * 1000; // Default 20 min
1384 
1385   /**
1386    * Configurations for master executor services.
1387    */
1388   public static final String MASTER_OPEN_REGION_THREADS =
1389       "hbase.master.executor.openregion.threads";
1390   public static final int MASTER_OPEN_REGION_THREADS_DEFAULT = 5;
1391 
1392   public static final String MASTER_CLOSE_REGION_THREADS =
1393       "hbase.master.executor.closeregion.threads";
1394   public static final int MASTER_CLOSE_REGION_THREADS_DEFAULT = 5;
1395 
1396   public static final String MASTER_SERVER_OPERATIONS_THREADS =
1397       "hbase.master.executor.serverops.threads";
1398   public static final int MASTER_SERVER_OPERATIONS_THREADS_DEFAULT = 5;
1399 
1400   /**
1401    * Number of threads used to dispatch merge operations to the regionservers.
1402    */
1403   public static final String MASTER_MERGE_DISPATCH_THREADS =
1404       "hbase.master.executor.merge.dispatch.threads";
1405   public static final int MASTER_MERGE_DISPATCH_THREADS_DEFAULT = 2;
1406 
1407   public static final String MASTER_META_SERVER_OPERATIONS_THREADS =
1408       "hbase.master.executor.meta.serverops.threads";
1409   public static final int MASTER_META_SERVER_OPERATIONS_THREADS_DEFAULT = 5;
1410 
1411   public static final String MASTER_LOG_REPLAY_OPS_THREADS =
1412       "hbase.master.executor.logreplayops.threads";
1413   public static final int MASTER_LOG_REPLAY_OPS_THREADS_DEFAULT = 10;
1414 
1415   /**
1416    * Number of rows in a batch operation above which a warning will be logged.
1417    */
1418   public static final String BATCH_ROWS_THRESHOLD_NAME = "hbase.rpc.rows.warning.threshold";
1419 
1420   /**
1421    * Default value of {@link #BATCH_ROWS_THRESHOLD_NAME}
1422    */
1423   public static final int BATCH_ROWS_THRESHOLD_DEFAULT = 5000;
1424 
1425   public static final int DEFAULT_SLOW_LOG_RING_BUFFER_SIZE = 256;
1426 
1427   public static final String SLOW_LOG_BUFFER_ENABLED_KEY =
1428     "hbase.regionserver.slowlog.buffer.enabled";
1429   public static final boolean DEFAULT_ONLINE_LOG_PROVIDER_ENABLED = false;
1430 
1431   /** The slowlog info family as a string*/
1432   private static final String SLOWLOG_INFO_FAMILY_STR = "info";
1433 
1434   /** The slowlog info family */
1435   public static final byte [] SLOWLOG_INFO_FAMILY = Bytes.toBytes(SLOWLOG_INFO_FAMILY_STR);
1436 
1437   public static final String SLOW_LOG_SYS_TABLE_ENABLED_KEY =
1438     "hbase.regionserver.slowlog.systable.enabled";
1439   public static final boolean DEFAULT_SLOW_LOG_SYS_TABLE_ENABLED_KEY = false;
1440 
1441   /**
1442    * This config is for experts: don't set its value unless you really know what you are doing.
1443    * When set to true, HBase client using SASL Kerberos will skip reverse DNS lookup and use
1444    * provided hostname of the destination for the principal instead.
1445    * See https://issues.apache.org/jira/browse/HBASE-25665 for more details.
1446    */
1447   @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
1448   public static final String UNSAFE_HBASE_CLIENT_KERBEROS_HOSTNAME_DISABLE_REVERSEDNS =
1449     "hbase.unsafe.client.kerberos.hostname.disable.reversedns";
1450   public static final boolean DEFAULT_UNSAFE_HBASE_CLIENT_KERBEROS_HOSTNAME_DISABLE_REVERSEDNS =
1451     false;
1452 
1453   private HConstants() {
1454     // Can't be instantiated with this ctor.
1455   }
1456 }