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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.
68  
69    /** The size data structures with minor version is 0 */
70    public static final int HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM = MAGIC_LENGTH + 2 * Bytes.SIZEOF_INT
71        + Bytes.SIZEOF_LONG;
72    /** The size of a version 2 HFile block header, minor version 1.
73     * There is a 1 byte checksum type, followed by a 4 byte bytesPerChecksum
74     * followed by another 4 byte value to store sizeofDataOnDisk.
75     */
76    public static final int HFILEBLOCK_HEADER_SIZE = HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM +
77      Bytes.SIZEOF_BYTE + 2 * Bytes.SIZEOF_INT;
78    /** Just an array of bytes of the right size. */
79    public static final byte[] HFILEBLOCK_DUMMY_HEADER = new byte[HFILEBLOCK_HEADER_SIZE];
80  
81    //End HFileBlockConstants.
82  
83    /**
84     * Status codes used for return values of bulk operations.
85     */
86    @InterfaceAudience.Private
87    public enum OperationStatusCode {
88      NOT_RUN,
89      SUCCESS,
90      BAD_FAMILY,
91      SANITY_CHECK_FAILURE,
92      FAILURE;
93    }
94  
95    /** long constant for zero */
96    public static final Long ZERO_L = Long.valueOf(0L);
97    public static final String NINES = "99999999999999";
98    public static final String ZEROES = "00000000000000";
99  
100   // For migration
101 
102   /** name of version file */
103   public static final String VERSION_FILE_NAME = "hbase.version";
104 
105   /**
106    * Current version of file system.
107    * Version 4 supports only one kind of bloom filter.
108    * Version 5 changes versions in catalog table regions.
109    * Version 6 enables blockcaching on catalog tables.
110    * Version 7 introduces hfile -- hbase 0.19 to 0.20..
111    * Version 8 introduces namespace
112    */
113   // public static final String FILE_SYSTEM_VERSION = "6";
114   public static final String FILE_SYSTEM_VERSION = "8";
115 
116   // Configuration parameters
117 
118   //TODO: Is having HBase homed on port 60k OK?
119 
120   /** Cluster is in distributed mode or not */
121   public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";
122 
123   /** Config for pluggable load balancers */
124   public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";
125 
126   /** Cluster is standalone or pseudo-distributed */
127   public static final boolean CLUSTER_IS_LOCAL = false;
128 
129   /** Cluster is fully-distributed */
130   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
131 
132   /** Default value for cluster distributed mode */
133   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
134 
135   /** default host address */
136   public static final String DEFAULT_HOST = "0.0.0.0";
137 
138   /** Parameter name for port master listens on. */
139   public static final String MASTER_PORT = "hbase.master.port";
140 
141   /** default port that the master listens on */
142   public static final int DEFAULT_MASTER_PORT = 16000;
143 
144   /** default port for master web api */
145   public static final int DEFAULT_MASTER_INFOPORT = 16010;
146 
147   /** Configuration key for master web API port */
148   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
149 
150   /** Parameter name for the master type being backup (waits for primary to go inactive). */
151   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
152 
153   /**
154    * by default every master is a possible primary master unless the conf explicitly overrides it
155    */
156   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
157 
158   /** Name of ZooKeeper quorum configuration parameter. */
159   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
160 
161   /** Name of ZooKeeper config file in conf/ directory. */
162   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
163 
164   /** Common prefix of ZooKeeper configuration properties */
165   public static final String ZK_CFG_PROPERTY_PREFIX =
166       "hbase.zookeeper.property.";
167 
168   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
169       ZK_CFG_PROPERTY_PREFIX.length();
170 
171   /**
172    * The ZK client port key in the ZK properties map. The name reflects the
173    * fact that this is not an HBase configuration key.
174    */
175   public static final String CLIENT_PORT_STR = "clientPort";
176 
177   /** Parameter name for the client port that the zookeeper listens on */
178   public static final String ZOOKEEPER_CLIENT_PORT =
179       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
180 
181   /** Default client port that the zookeeper listens on */
182   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
183 
184   /**
185    * Parameter name for the wait time for the recoverable zookeeper
186    */
187   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME =
188       "hbase.zookeeper.recoverable.waittime";
189 
190   /** Default wait time for the recoverable zookeeper */
191   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
192 
193   /** Parameter name for the root dir in ZK for this cluster */
194   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
195 
196   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
197 
198   /**
199    * Parameter name for the limit on concurrent client-side zookeeper
200    * connections
201    */
202   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
203       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
204 
205   /** Parameter name for the ZK data directory */
206   public static final String ZOOKEEPER_DATA_DIR =
207       ZK_CFG_PROPERTY_PREFIX + "dataDir";
208 
209   /** Parameter name for the ZK tick time */
210   public static final String ZOOKEEPER_TICK_TIME =
211       ZK_CFG_PROPERTY_PREFIX + "tickTime";
212 
213   /** Default limit on concurrent client-side zookeeper connections */
214   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
215 
216   /** Configuration key for ZooKeeper session timeout */
217   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
218 
219   /** Default value for ZooKeeper session timeout */
220   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
221 
222   /** Configuration key for whether to use ZK.multi */
223   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
224 
225   /** Parameter name for port region server listens on. */
226   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
227 
228   /** Default port region server listens on. */
229   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
230 
231   /** default port for region server web api */
232   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
233 
234   /** A configuration key for regionserver info port */
235   public static final String REGIONSERVER_INFO_PORT =
236     "hbase.regionserver.info.port";
237 
238   /** A flag that enables automatic selection of regionserver info port */
239   public static final String REGIONSERVER_INFO_PORT_AUTO =
240       REGIONSERVER_INFO_PORT + ".auto";
241 
242   /** Parameter name for what region server implementation to use. */
243   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
244 
245   /** Parameter name for what master implementation to use. */
246   public static final String MASTER_IMPL= "hbase.master.impl";
247 
248   /** Parameter name for what hbase client implementation to use. */
249   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
250 
251   /** Parameter name for how often threads should wake up */
252   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
253 
254   /** Default value for thread wake frequency */
255   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
256 
257   /** Parameter name for how often we should try to write a version file, before failing */
258   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
259 
260   /** Parameter name for how often we should try to write a version file, before failing */
261   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
262 
263   /** Parameter name for how often a region should should perform a major compaction */
264   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
265 
266   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
267   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
268   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
269 
270   /** Parameter name for HBase instance root directory */
271   public static final String HBASE_DIR = "hbase.rootdir";
272 
273   /** Parameter name for HBase client IPC pool type */
274   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
275 
276   /** Parameter name for HBase client IPC pool size */
277   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
278 
279   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
280   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
281 
282   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
283   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
284     "hbase.client.meta.operation.timeout";
285 
286   /** Default HBase client operation timeout, which is tantamount to a blocking call */
287   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = Integer.MAX_VALUE;
288 
289   /** Used to construct the name of the log directory for a region server */
290   public static final String HREGION_LOGDIR_NAME = "WALs";
291 
292   /** Used to construct the name of the splitlog directory for a region server */
293   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
294 
295   /** Like the previous, but for old logs that are about to be deleted */
296   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
297 
298   public static final String CORRUPT_DIR_NAME = "corrupt";
299 
300   /** Used by HBCK to sideline backup data */
301   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
302 
303   /** Any artifacts left from migration can be moved here */
304   public static final String MIGRATION_NAME = ".migration";
305 
306   /**
307    * The directory from which co-processor/custom filter jars can be loaded
308    * dynamically by the region servers. This value can be overridden by the
309    * hbase.dynamic.jars.dir config.
310    */
311   public static final String LIB_DIR = "lib";
312 
313   /** Used to construct the name of the compaction directory during compaction */
314   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
315 
316   /** Conf key for the max file size after which we split the region */
317   public static final String HREGION_MAX_FILESIZE =
318       "hbase.hregion.max.filesize";
319 
320   /** Default maximum file size */
321   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
322 
323   /**
324    * Max size of single row for Get's or Scan's without in-row scanning flag set.
325    */
326   public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
327 
328   /**
329    * Default max row size (1 Gb).
330    */
331   public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
332 
333   /**
334    * The max number of threads used for opening and closing stores or store
335    * files in parallel
336    */
337   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
338     "hbase.hstore.open.and.close.threads.max";
339 
340   /**
341    * The default number for the max number of threads used for opening and
342    * closing stores or store files in parallel
343    */
344   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
345 
346 
347   /** Conf key for the memstore size at which we flush the memstore */
348   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
349       "hbase.hregion.memstore.flush.size";
350 
351   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
352       "hbase.hregion.edits.replay.skip.errors";
353 
354   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
355       false;
356 
357   /** Maximum value length, enforced on KeyValue construction */
358   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
359 
360   /** name of the file for unique cluster ID */
361   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
362 
363   /** Default value for cluster ID */
364   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
365 
366   /** Parameter name for # days to keep MVCC values during a major compaction */
367   public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
368   /** At least to keep MVCC values in hfiles for 5 days */
369   public static final int MIN_KEEP_SEQID_PERIOD = 5;
370 
371   // Always store the location of the root table's HRegion.
372   // This HRegion is never split.
373 
374   // region name = table + startkey + regionid. This is the row key.
375   // each row in the root and meta tables describes exactly 1 region
376   // Do we ever need to know all the information that we are storing?
377 
378   // Note that the name of the root table starts with "-" and the name of the
379   // meta table starts with "." Why? it's a trick. It turns out that when we
380   // store region names in memory, we use a SortedMap. Since "-" sorts before
381   // "." (and since no other table name can start with either of these
382   // characters, the root region will always be the first entry in such a Map,
383   // followed by all the meta regions (which will be ordered by their starting
384   // row key as well), followed by all user tables. So when the Master is
385   // choosing regions to assign, it will always choose the root region first,
386   // followed by the meta regions, followed by user regions. Since the root
387   // and meta regions always need to be on-line, this ensures that they will
388   // be the first to be reassigned if the server(s) they are being served by
389   // should go down.
390 
391 
392   /**
393    * The hbase:meta table's name.
394    *
395    */
396   @Deprecated  // for compat from 0.94 -> 0.96.
397   public static final byte[] META_TABLE_NAME = TableName.META_TABLE_NAME.getName();
398 
399   public static final String BASE_NAMESPACE_DIR = "data";
400 
401   /** delimiter used between portions of a region name */
402   public static final int META_ROW_DELIMITER = ',';
403 
404   /** The catalog family as a string*/
405   public static final String CATALOG_FAMILY_STR = "info";
406 
407   /** The catalog family */
408   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
409 
410   /** The RegionInfo qualifier as a string */
411   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
412 
413   /** The regioninfo column qualifier */
414   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
415 
416   /** The server column qualifier */
417   public static final String SERVER_QUALIFIER_STR = "server";
418   /** The server column qualifier */
419   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes(SERVER_QUALIFIER_STR);
420 
421   /** The startcode column qualifier */
422   public static final String STARTCODE_QUALIFIER_STR = "serverstartcode";
423   /** The startcode column qualifier */
424   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes(STARTCODE_QUALIFIER_STR);
425 
426   /** The open seqnum column qualifier */
427   public static final String SEQNUM_QUALIFIER_STR = "seqnumDuringOpen";
428   /** The open seqnum column qualifier */
429   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes(SEQNUM_QUALIFIER_STR);
430 
431   /** The state column qualifier */
432   public static final String STATE_QUALIFIER_STR = "state";
433 
434   public static final byte [] STATE_QUALIFIER = Bytes.toBytes(STATE_QUALIFIER_STR);
435 
436   /**
437    * The serverName column qualifier. Its the server where the region is
438    * transitioning on, while column server is the server where the region is
439    * opened on. They are the same when the region is in state OPEN.
440    */
441   public static final String SERVERNAME_QUALIFIER_STR = "sn";
442 
443   public static final byte [] SERVERNAME_QUALIFIER = Bytes.toBytes(SERVERNAME_QUALIFIER_STR);
444 
445   /** The lower-half split region column qualifier */
446   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
447 
448   /** The upper-half split region column qualifier */
449   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
450 
451   /** The lower-half merge region column qualifier */
452   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
453 
454   /** The upper-half merge region column qualifier */
455   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
456 
457   /** The catalog family as a string*/
458   public static final String TABLE_FAMILY_STR = "table";
459 
460   /** The catalog family */
461   public static final byte [] TABLE_FAMILY = Bytes.toBytes(TABLE_FAMILY_STR);
462 
463   /** The serialized table state qualifier */
464   public static final byte[] TABLE_STATE_QUALIFIER = Bytes.toBytes("state");
465 
466 
467   /**
468    * The meta table version column qualifier.
469    * We keep current version of the meta table in this column in <code>-ROOT-</code>
470    * table: i.e. in the 'info:v' column.
471    */
472   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
473 
474   /**
475    * The current version of the meta table.
476    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
477    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
478    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
479    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
480    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
481    * byte[] serialization from Writables to Protobuf.
482    * See HRegionInfo.VERSION
483    */
484   public static final short META_VERSION = 1;
485 
486   // Other constants
487 
488   /**
489    * An empty instance.
490    */
491   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
492 
493   /**
494    * Used by scanners, etc when they want to start at the beginning of a region
495    */
496   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
497 
498   /**
499    * Last row in a table.
500    */
501   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
502 
503   /**
504     * Used by scanners and others when they're trying to detect the end of a
505     * table
506     */
507   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
508 
509   /**
510    * Max length a row can have because of the limitation in TFile.
511    */
512   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
513 
514   /**
515    * Timestamp to use when we want to refer to the latest cell.
516    * This is the timestamp sent by clients when no timestamp is specified on
517    * commit.
518    */
519   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
520 
521   /**
522    * Timestamp to use when we want to refer to the oldest cell.
523    */
524   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
525 
526   /**
527    * LATEST_TIMESTAMP in bytes form
528    */
529   public static final byte [] LATEST_TIMESTAMP_BYTES = {
530     // big-endian
531     (byte) (LATEST_TIMESTAMP >>> 56),
532     (byte) (LATEST_TIMESTAMP >>> 48),
533     (byte) (LATEST_TIMESTAMP >>> 40),
534     (byte) (LATEST_TIMESTAMP >>> 32),
535     (byte) (LATEST_TIMESTAMP >>> 24),
536     (byte) (LATEST_TIMESTAMP >>> 16),
537     (byte) (LATEST_TIMESTAMP >>> 8),
538     (byte) LATEST_TIMESTAMP,
539   };
540 
541   /**
542    * Define for 'return-all-versions'.
543    */
544   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
545 
546   /**
547    * Unlimited time-to-live.
548    */
549 //  public static final int FOREVER = -1;
550   public static final int FOREVER = Integer.MAX_VALUE;
551 
552   /**
553    * Seconds in a week
554    */
555   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
556 
557   /**
558    * Seconds in a day, hour and minute
559    */
560   public static final int DAY_IN_SECONDS = 24 * 60 * 60;
561   public static final int HOUR_IN_SECONDS = 60 * 60;
562   public static final int MINUTE_IN_SECONDS = 60;
563 
564   //TODO: although the following are referenced widely to format strings for
565   //      the shell. They really aren't a part of the public API. It would be
566   //      nice if we could put them somewhere where they did not need to be
567   //      public. They could have package visibility
568   public static final String NAME = "NAME";
569   public static final String VERSIONS = "VERSIONS";
570   public static final String IN_MEMORY = "IN_MEMORY";
571   public static final String METADATA = "METADATA";
572   public static final String CONFIGURATION = "CONFIGURATION";
573 
574   /**
575    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
576    * run out of array items.  Retries beyond this use the last number in the array.  So, for
577    * example, if hbase.client.pause is 1 second, and maximum retries count
578    * hbase.client.retries.number is 10, we will retry at the following intervals:
579    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
580    * With 100ms, a back-off of 200 means 20s
581    */
582   public static final int RETRY_BACKOFF[] = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
583 
584   public static final String REGION_IMPL = "hbase.hregion.impl";
585 
586   /** modifyTable op for replacing the table descriptor */
587   @InterfaceAudience.Private
588   public static enum Modify {
589     CLOSE_REGION,
590     TABLE_COMPACT,
591     TABLE_FLUSH,
592     TABLE_MAJOR_COMPACT,
593     TABLE_SET_HTD,
594     TABLE_SPLIT
595   }
596 
597   /**
598    * Scope tag for locally scoped data.
599    * This data will not be replicated.
600    */
601   public static final int REPLICATION_SCOPE_LOCAL = 0;
602 
603   /**
604    * Scope tag for globally scoped data.
605    * This data will be replicated to all peers.
606    */
607   public static final int REPLICATION_SCOPE_GLOBAL = 1;
608 
609   /**
610    * Default cluster ID, cannot be used to identify a cluster so a key with
611    * this value means it wasn't meant for replication.
612    */
613   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
614 
615     /**
616      * Parameter name for maximum number of bytes returned when calling a
617      * scanner's next method.
618      */
619   public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
620       "hbase.client.scanner.max.result.size";
621 
622   /**
623    * Maximum number of bytes returned when calling a scanner's next method.
624    * Note that when a single row is larger than this limit the row is still
625    * returned completely.
626    *
627    * The default value is 2MB.
628    */
629   public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
630 
631   /**
632    * Parameter name for client pause value, used mostly as value to wait
633    * before running a retry of a failed get, region lookup, etc.
634    */
635   public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
636 
637   /**
638    * Default value of {@link #HBASE_CLIENT_PAUSE}.
639    */
640   public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
641 
642   /**
643    * The maximum number of concurrent connections the client will maintain.
644    */
645   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
646 
647   /**
648    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
649    */
650   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
651 
652   /**
653    * The maximum number of concurrent connections the client will maintain to a single
654    * RegionServer.
655    */
656   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
657 
658   /**
659    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
660    */
661   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
662 
663   /**
664    * The maximum number of concurrent connections the client will maintain to a single
665    * Region.
666    */
667   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
668 
669   /**
670    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
671    */
672   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
673 
674   /**
675    * Parameter name for server pause value, used mostly as value to wait before
676    * running a retry of a failed operation.
677    */
678   public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
679 
680   /**
681    * Default value of {@link #HBASE_SERVER_PAUSE}.
682    */
683   public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
684 
685   /**
686    * Parameter name for maximum retries, used as maximum for all retryable
687    * operations such as fetching of the root region from root region server,
688    * getting a cell's value, starting a row update, etc.
689    */
690   public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
691 
692   /**
693    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
694    */
695   public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
696 
697   /**
698    * Parameter name to set the default scanner caching for all clients.
699    */
700   public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
701 
702   /**
703    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
704    */
705   public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = Integer.MAX_VALUE;
706 
707   /**
708    * Parameter name for number of rows that will be fetched when calling next on
709    * a scanner if it is not served from memory. Higher caching values will
710    * enable faster scanners but will eat up more memory and some calls of next
711    * may take longer and longer times when the cache is empty.
712    */
713   public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
714 
715   /**
716    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
717    */
718   public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
719 
720   /**
721    * Parameter name for number of versions, kept by meta table.
722    */
723   public static final String HBASE_META_VERSIONS = "hbase.meta.versions";
724 
725   /**
726    * Default value of {@link #HBASE_META_VERSIONS}.
727    */
728   public static final int DEFAULT_HBASE_META_VERSIONS = 3;
729 
730   /**
731    * Parameter name for number of versions, kept by meta table.
732    */
733   public static final String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
734 
735   /**
736    * Default value of {@link #HBASE_META_BLOCK_SIZE}.
737    */
738   public static final int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
739 
740   /**
741    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
742    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
743    * for all intents and purposes, are the same except for their instance ids, then they will not be
744    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
745    * even if the instance ids are the same, it could result in non-shared
746    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
747    * differ.
748    */
749   public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
750 
751   /**
752    * The client scanner timeout period in milliseconds.
753    */
754   public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD =
755       "hbase.client.scanner.timeout.period";
756 
757   /**
758    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
759    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
760    */
761   @Deprecated
762   public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
763       "hbase.regionserver.lease.period";
764 
765   /**
766    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
767    */
768   public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
769 
770   /**
771    * timeout for each RPC
772    */
773   public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
774 
775   /**
776    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
777    */
778   public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
779 
780   /**
781    * timeout for short operation RPC
782    */
783   public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY = "hbase.rpc.shortoperation.timeout";
784 
785   /**
786    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
787    */
788   public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
789 
790   /**
791    * Value indicating the server name was saved with no sequence number.
792    */
793   public static final long NO_SEQNUM = -1;
794 
795 
796   /*
797    * cluster replication constants.
798    */
799   public static final String
800       REPLICATION_ENABLE_KEY = "hbase.replication";
801   public static final boolean
802       REPLICATION_ENABLE_DEFAULT = true;
803   public static final String
804       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
805   public static final String
806       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
807   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
808     "org.apache.hadoop.hbase.replication.regionserver.Replication";
809 
810   /** HBCK special code name used as server name when manipulating ZK nodes */
811   public static final String HBCK_CODE_NAME = "HBCKServerName";
812 
813   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
814     "hbase.regionserver.hostname.seen.by.master";
815 
816   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
817       "hbase.master.logcleaner.plugins";
818 
819   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
820     "hbase.regionserver.region.split.policy";
821 
822   /** Whether nonces are enabled; default is true. */
823   public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
824 
825   /**
826    * Configuration key for the size of the block cache
827    */
828   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
829     "hfile.block.cache.size";
830 
831   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
832 
833   /*
834     * Minimum percentage of free heap necessary for a successful cluster startup.
835     */
836   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
837 
838   public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile
839       ("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
840   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
841       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
842 
843   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
844   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
845   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
846       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
847       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
848 
849   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
850   public static final int SOCKET_RETRY_WAIT_MS = 200;
851 
852   /** Host name of the local machine */
853   public static final String LOCALHOST = "localhost";
854 
855   /**
856    * If this parameter is set to true, then hbase will read
857    * data and then verify checksums. Checksum verification
858    * inside hdfs will be switched off.  However, if the hbase-checksum
859    * verification fails, then it will switch back to using
860    * hdfs checksums for verifiying data that is being read from storage.
861    *
862    * If this parameter is set to false, then hbase will not
863    * verify any checksums, instead it will depend on checksum verification
864    * being done in the hdfs client.
865    */
866   public static final String HBASE_CHECKSUM_VERIFICATION =
867       "hbase.regionserver.checksum.verify";
868 
869   public static final String LOCALHOST_IP = "127.0.0.1";
870 
871   /** Conf key that enables unflushed WAL edits directly being replayed to region servers */
872   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
873   /**
874    * Default 'distributed log replay' as true since hbase 0.99.0
875    */
876   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = true;
877   public static final String DISALLOW_WRITES_IN_RECOVERING =
878       "hbase.regionserver.disallow.writes.when.recovering";
879   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
880 
881   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
882   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
883 
884   /*
885    * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
886    * -1  => Disable aborting
887    * 0   => Abort if even a single handler has died
888    * 0.x => Abort only when this percent of handlers have died
889    * 1   => Abort only all of the handers have died
890    */
891   public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
892 		  "hbase.regionserver.handler.abort.on.error.percent";
893   public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
894 
895   //High priority handlers to deal with admin requests and system table operation requests
896   public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
897       "hbase.regionserver.metahandler.count";
898   public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 10;
899 
900   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
901       "hbase.regionserver.replication.handler.count";
902   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
903 
904   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
905   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
906 
907   /** Conf key that specifies timeout value to wait for a region ready */
908   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
909       "hbase.master.log.replay.wait.region.timeout";
910 
911   /** Conf key for enabling meta replication */
912   public static final String USE_META_REPLICAS = "hbase.meta.replicas.use";
913   public static final boolean DEFAULT_USE_META_REPLICAS = false;
914   public static final String META_REPLICAS_NUM = "hbase.meta.replica.count";
915   public static final int DEFAULT_META_REPLICA_NUM = 1;
916 
917   /**
918    * The name of the configuration parameter that specifies
919    * the number of bytes in a newly created checksum chunk.
920    */
921   public static final String BYTES_PER_CHECKSUM =
922       "hbase.hstore.bytes.per.checksum";
923 
924   /**
925    * The name of the configuration parameter that specifies
926    * the name of an algorithm that is used to compute checksums
927    * for newly created blocks.
928    */
929   public static final String CHECKSUM_TYPE_NAME =
930       "hbase.hstore.checksum.algorithm";
931 
932   /** Enable file permission modification from standard hbase */
933   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
934   /** File permission umask to use when creating hbase data files */
935   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
936 
937   /** Configuration name of WAL Compression */
938   public static final String ENABLE_WAL_COMPRESSION =
939     "hbase.regionserver.wal.enablecompression";
940 
941   /** Configuration name of WAL storage policy
942    * Valid values are:
943    *  NONE: no preference in destination of replicas
944    *  ONE_SSD: place only one replica in SSD and the remaining in default storage
945    *  and ALL_SSD: place all replica on SSD
946    *
947    * See http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/ArchivalStorage.html*/
948   public static final String WAL_STORAGE_POLICY = "hbase.wal.storage.policy";
949   public static final String DEFAULT_WAL_STORAGE_POLICY = "NONE";
950 
951   /** Region in Transition metrics threshold time */
952   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
953 
954   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
955 
956   /**
957    * The byte array represents for NO_NEXT_INDEXED_KEY;
958    * The actual value is irrelevant because this is always compared by reference.
959    */
960   public static final Cell NO_NEXT_INDEXED_KEY = new KeyValue();
961   /** delimiter used between portions of a region name */
962   public static final int DELIMITER = ',';
963   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
964       "hbase.config.read.zookeeper.config";
965   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
966       false;
967 
968   /**
969    * QOS attributes: these attributes are used to demarcate RPC call processing
970    * by different set of handlers. For example, HIGH_QOS tagged methods are
971    * handled by high priority handlers.
972    */
973   public static final int NORMAL_QOS = 0;
974   public static final int QOS_THRESHOLD = 10;
975   public static final int HIGH_QOS = 200;
976   public static final int REPLICATION_QOS = 5; // normal_QOS < replication_QOS < high_QOS
977   public static final int REPLAY_QOS = 6; // REPLICATION_QOS < REPLAY_QOS < high_QOS
978   public static final int ADMIN_QOS = 100; // QOS_THRESHOLD < ADMIN_QOS < high_QOS
979   public static final int SYSTEMTABLE_QOS = HIGH_QOS;
980 
981   /** Directory under /hbase where archived hfiles are stored */
982   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
983 
984   /**
985    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
986    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
987    * uni-directional.
988    */
989   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
990 
991   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
992   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
993 
994   /** Temporary directory used for table creation and deletion */
995   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
996   /**
997    * The period (in milliseconds) between computing region server point in time metrics
998    */
999   public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
1000   public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
1001   /** Directories that are not HBase table directories */
1002   public static final List<String> HBASE_NON_TABLE_DIRS =
1003     Collections.unmodifiableList(Arrays.asList(new String[] {
1004       HBCK_SIDELINEDIR_NAME, HBASE_TEMP_DIRECTORY, MIGRATION_NAME
1005     }));
1006 
1007   /** Directories that are not HBase user table directories */
1008   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
1009     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
1010       new String[] { TableName.META_TABLE_NAME.getNameAsString() },
1011       HBASE_NON_TABLE_DIRS.toArray())));
1012 
1013   /** Health script related settings. */
1014   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
1015   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
1016   public static final String HEALTH_CHORE_WAKE_FREQ =
1017       "hbase.node.health.script.frequency";
1018   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
1019   /**
1020    * The maximum number of health check failures a server can encounter consecutively.
1021    */
1022   public static final String HEALTH_FAILURE_THRESHOLD =
1023       "hbase.node.health.failure.threshold";
1024   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
1025 
1026 
1027   /**
1028    * Setting to activate, or not, the publication of the status by the master. Default
1029    *  notification is by a multicast message.
1030    */
1031   public static final String STATUS_PUBLISHED = "hbase.status.published";
1032   public static final boolean STATUS_PUBLISHED_DEFAULT = false;
1033 
1034   /**
1035    * IP to use for the multicast status messages between the master and the clients.
1036    * The default address is chosen as one among others within the ones suitable for multicast
1037    * messages.
1038    */
1039   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
1040   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
1041 
1042   /**
1043    * The address to use for binding the local socket for receiving multicast. Defaults to
1044    * 0.0.0.0.
1045    * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
1046    */
1047   public static final String STATUS_MULTICAST_BIND_ADDRESS = "hbase.status.multicast.bind.address.ip";
1048   public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
1049 
1050   /**
1051    * The port to use for the multicast messages.
1052    */
1053   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
1054   public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
1055 
1056   public static final long NO_NONCE = 0;
1057 
1058   /** Default cipher for encryption */
1059   public static final String CIPHER_AES = "AES";
1060 
1061   /** Configuration key for the crypto algorithm provider, a class name */
1062   public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
1063 
1064   /** Configuration key for the crypto key provider, a class name */
1065   public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
1066 
1067   /** Configuration key for the crypto key provider parameters */
1068   public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
1069       "hbase.crypto.keyprovider.parameters";
1070 
1071   /** Configuration key for the name of the master key for the cluster, a string */
1072   public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
1073 
1074   /** Configuration key for the name of the alternate master key for the cluster, a string */
1075   public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
1076     "hbase.crypto.master.alternate.key.name";
1077 
1078   /** Configuration key for the algorithm to use when encrypting the WAL, a string */
1079   public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
1080 
1081   /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
1082   public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
1083 
1084   /** Configuration key for the algorithm used for creating jks key, a string */
1085   public static final String CRYPTO_KEY_ALGORITHM_CONF_KEY = "hbase.crypto.key.algorithm";
1086 
1087   /** Configuration key for the name of the alternate cipher algorithm for the cluster, a string */
1088   public static final String CRYPTO_ALTERNATE_KEY_ALGORITHM_CONF_KEY =
1089       "hbase.crypto.alternate.key.algorithm";
1090 
1091   /** Configuration key for enabling WAL encryption, a boolean */
1092   public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
1093 
1094   /** Configuration key for setting RPC codec class name */
1095   public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
1096 
1097   /** Configuration key for setting replication codec class name */
1098   public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
1099 
1100   /** Config for pluggable consensus provider */
1101   public static final String HBASE_COORDINATED_STATE_MANAGER_CLASS =
1102     "hbase.coordinated.state.manager.class";
1103 
1104   /** Configuration key for SplitLog manager timeout */
1105   public static final String HBASE_SPLITLOG_MANAGER_TIMEOUT = "hbase.splitlog.manager.timeout";
1106 
1107   /**
1108    * Configuration keys for Bucket cache
1109    */
1110   // TODO moving these bucket cache implementation specific configs to this level is violation of
1111   // encapsulation. But as these has to be referred from hbase-common and bucket cache
1112   // sits in hbase-server, there were no other go! Can we move the cache implementation to
1113   // hbase-common?
1114 
1115   /**
1116    * Current ioengine options in include: heap, offheap and file:PATH (where PATH is the path
1117    * to the file that will host the file-based cache.  See BucketCache#getIOEngineFromName() for
1118    * list of supported ioengine options.
1119    * <p>Set this option and a non-zero {@link #BUCKET_CACHE_SIZE_KEY} to enable bucket cache.
1120    */
1121   public static final String BUCKET_CACHE_IOENGINE_KEY = "hbase.bucketcache.ioengine";
1122 
1123   /**
1124    * When using bucket cache, this is a float that EITHER represents a percentage of total heap
1125    * memory size to give to the cache (if < 1.0) OR, it is the capacity in megabytes of the cache.
1126    */
1127   public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1128 
1129   /**
1130    * HConstants for fast fail on the client side follow
1131    */
1132   /**
1133    * Config for enabling/disabling the fast fail mode.
1134    */
1135   public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1136       "hbase.client.fast.fail.mode.enabled";
1137 
1138   public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT =
1139       false;
1140 
1141   public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1142       "hbase.client.fastfail.threshold";
1143 
1144   public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT =
1145       60000;
1146 
1147   public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1148       "hbase.client.fast.fail.cleanup.duration";
1149 
1150   public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT =
1151       600000;
1152 
1153   public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1154       "hbase.client.fast.fail.interceptor.impl";
1155 
1156   /** Config key for if the server should send backpressure and if the client should listen to
1157    * that backpressure from the server */
1158   public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1159   public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1160 
1161   public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1162       "hbase.heap.occupancy.low_water_mark";
1163   public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1164   public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1165       "hbase.heap.occupancy.high_water_mark";
1166   public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1167 
1168   private HConstants() {
1169     // Can't be instantiated with this ctor.
1170   }
1171 }