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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase;
19  
20  import static org.apache.hadoop.hbase.io.hfile.BlockType.MAGIC_LENGTH;
21  
22  import java.nio.ByteBuffer;
23  import java.nio.charset.Charset;
24  import java.util.Arrays;
25  import java.util.Collections;
26  import java.util.List;
27  import java.util.UUID;
28  import java.util.regex.Pattern;
29  
30  import org.apache.commons.lang.ArrayUtils;
31  import org.apache.hadoop.hbase.classification.InterfaceAudience;
32  import org.apache.hadoop.hbase.classification.InterfaceStability;
33  import org.apache.hadoop.hbase.util.Bytes;
34  
35  /**
36   * HConstants holds a bunch of HBase-related constants
37   */
38  @InterfaceAudience.Public
39  @InterfaceStability.Stable
40  public final class HConstants {
41    // NOTICE!!!! Please do not add a constants here, unless they are referenced by a lot of classes.
42  
43    //Bytes.UTF8_ENCODING should be updated if this changed
44    /** When we encode strings, we always specify UTF8 encoding */
45    public static final String UTF8_ENCODING = "UTF-8";
46  
47    //Bytes.UTF8_CHARSET should be updated if this changed
48    /** When we encode strings, we always specify UTF8 encoding */
49    public static final Charset UTF8_CHARSET = Charset.forName(UTF8_ENCODING);
50    /**
51     * Default block size for an HFile.
52     */
53    public final static int DEFAULT_BLOCKSIZE = 64 * 1024;
54  
55    /** Used as a magic return value while optimized index key feature enabled(HBASE-7845) */
56    public final static int INDEX_KEY_MAGIC = -2;
57    /*
58       * Name of directory that holds recovered edits written by the wal log
59       * splitting code, one per region
60       */
61    public static final String RECOVERED_EDITS_DIR = "recovered.edits";
62    /**
63     * The first four bytes of Hadoop RPC connections
64     */
65    public static final ByteBuffer RPC_HEADER = ByteBuffer.wrap("HBas".getBytes());
66    public static final byte RPC_CURRENT_VERSION = 0;
67  
68    // HFileBlock constants.
69  
70    /** The size data structures with minor version is 0 */
71    public static final int HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM = MAGIC_LENGTH + 2 * Bytes.SIZEOF_INT
72        + Bytes.SIZEOF_LONG;
73    /** The size of a version 2 HFile block header, minor version 1.
74     * There is a 1 byte checksum type, followed by a 4 byte bytesPerChecksum
75     * followed by another 4 byte value to store sizeofDataOnDisk.
76     */
77    public static final int HFILEBLOCK_HEADER_SIZE = HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM +
78      Bytes.SIZEOF_BYTE + 2 * Bytes.SIZEOF_INT;
79    /** Just an array of bytes of the right size. */
80    public static final byte[] HFILEBLOCK_DUMMY_HEADER = new byte[HFILEBLOCK_HEADER_SIZE];
81  
82    //End HFileBlockConstants.
83  
84    /**
85     * Status codes used for return values of bulk operations.
86     */
87    @InterfaceAudience.Private
88    public enum OperationStatusCode {
89      NOT_RUN,
90      SUCCESS,
91      BAD_FAMILY,
92      SANITY_CHECK_FAILURE,
93      FAILURE;
94    }
95  
96    /** long constant for zero */
97    public static final Long ZERO_L = Long.valueOf(0L);
98    public static final String NINES = "99999999999999";
99    public static final String ZEROES = "00000000000000";
100 
101   // For migration
102 
103   /** name of version file */
104   public static final String VERSION_FILE_NAME = "hbase.version";
105 
106   /**
107    * Current version of file system.
108    * Version 4 supports only one kind of bloom filter.
109    * Version 5 changes versions in catalog table regions.
110    * Version 6 enables blockcaching on catalog tables.
111    * Version 7 introduces hfile -- hbase 0.19 to 0.20..
112    * Version 8 introduces namespace
113    */
114   // public static final String FILE_SYSTEM_VERSION = "6";
115   public static final String FILE_SYSTEM_VERSION = "8";
116 
117   // Configuration parameters
118 
119   //TODO: Is having HBase homed on port 60k OK?
120 
121   /** Cluster is in distributed mode or not */
122   public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";
123 
124   /** Config for pluggable load balancers */
125   public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";
126 
127   /** Cluster is standalone or pseudo-distributed */
128   public static final boolean CLUSTER_IS_LOCAL = false;
129 
130   /** Cluster is fully-distributed */
131   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
132 
133   /** Default value for cluster distributed mode */
134   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
135 
136   /** default host address */
137   public static final String DEFAULT_HOST = "0.0.0.0";
138 
139   /** Parameter name for port master listens on. */
140   public static final String MASTER_PORT = "hbase.master.port";
141 
142   /** default port that the master listens on */
143   public static final int DEFAULT_MASTER_PORT = 16000;
144 
145   /** default port for master web api */
146   public static final int DEFAULT_MASTER_INFOPORT = 16010;
147 
148   /** Configuration key for master web API port */
149   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
150 
151   /** Parameter name for the master type being backup (waits for primary to go inactive). */
152   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
153 
154   /** by default every master is a possible primary master unless the conf explicitly overrides it */
155   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
156 
157   /** Name of ZooKeeper quorum configuration parameter. */
158   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
159 
160   /** Name of ZooKeeper config file in conf/ directory. */
161   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
162 
163   /** Common prefix of ZooKeeper configuration properties */
164   public static final String ZK_CFG_PROPERTY_PREFIX =
165       "hbase.zookeeper.property.";
166 
167   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
168       ZK_CFG_PROPERTY_PREFIX.length();
169 
170   /**
171    * The ZK client port key in the ZK properties map. The name reflects the
172    * fact that this is not an HBase configuration key.
173    */
174   public static final String CLIENT_PORT_STR = "clientPort";
175 
176   /** Parameter name for the client port that the zookeeper listens on */
177   public static final String ZOOKEEPER_CLIENT_PORT =
178       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
179 
180   /** Default client port that the zookeeper listens on */
181   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
182 
183   /** Parameter name for the wait time for the recoverable zookeeper */
184   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";
185 
186   /** Default wait time for the recoverable zookeeper */
187   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
188 
189   /** Parameter name for the root dir in ZK for this cluster */
190   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
191 
192   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
193 
194   /**
195    * Parameter name for the limit on concurrent client-side zookeeper
196    * connections
197    */
198   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
199       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
200 
201   /** Parameter name for the ZK data directory */
202   public static final String ZOOKEEPER_DATA_DIR =
203       ZK_CFG_PROPERTY_PREFIX + "dataDir";
204 
205   /** Default limit on concurrent client-side zookeeper connections */
206   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
207 
208   /** Configuration key for ZooKeeper session timeout */
209   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
210 
211   /** Default value for ZooKeeper session timeout */
212   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
213 
214   /** Configuration key for whether to use ZK.multi */
215   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
216 
217   /** Parameter name for port region server listens on. */
218   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
219 
220   /** Default port region server listens on. */
221   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
222 
223   /** default port for region server web api */
224   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
225 
226   /** A configuration key for regionserver info port */
227   public static final String REGIONSERVER_INFO_PORT =
228     "hbase.regionserver.info.port";
229 
230   /** A flag that enables automatic selection of regionserver info port */
231   public static final String REGIONSERVER_INFO_PORT_AUTO =
232       REGIONSERVER_INFO_PORT + ".auto";
233 
234   /** Parameter name for what region server implementation to use. */
235   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
236 
237   /** Parameter name for what master implementation to use. */
238   public static final String MASTER_IMPL= "hbase.master.impl";
239 
240   /** Parameter name for what hbase client implementation to use. */
241   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
242 
243   /** Parameter name for how often threads should wake up */
244   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
245 
246   /** Default value for thread wake frequency */
247   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
248 
249   /** Parameter name for how often we should try to write a version file, before failing */
250   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
251 
252   /** Parameter name for how often we should try to write a version file, before failing */
253   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
254 
255   /** Parameter name for how often a region should should perform a major compaction */
256   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
257 
258   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
259   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
260   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
261 
262   /** Parameter name for HBase instance root directory */
263   public static final String HBASE_DIR = "hbase.rootdir";
264 
265   /** Parameter name for HBase client IPC pool type */
266   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
267 
268   /** Parameter name for HBase client IPC pool size */
269   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
270 
271   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
272   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
273 
274   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
275   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
276     "hbase.client.meta.operation.timeout";
277 
278   /** Default HBase client operation timeout, which is tantamount to a blocking call */
279   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = Integer.MAX_VALUE;
280 
281   /** Used to construct the name of the log directory for a region server */
282   public static final String HREGION_LOGDIR_NAME = "WALs";
283 
284   /** Used to construct the name of the splitlog directory for a region server */
285   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
286 
287   /** Like the previous, but for old logs that are about to be deleted */
288   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
289 
290   public static final String CORRUPT_DIR_NAME = "corrupt";
291 
292   /** Used by HBCK to sideline backup data */
293   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
294 
295   /** Any artifacts left from migration can be moved here */
296   public static final String MIGRATION_NAME = ".migration";
297 
298   /**
299    * The directory from which co-processor/custom filter jars can be loaded
300    * dynamically by the region servers. This value can be overridden by the
301    * hbase.dynamic.jars.dir config.
302    */
303   public static final String LIB_DIR = "lib";
304 
305   /** Used to construct the name of the compaction directory during compaction */
306   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
307 
308   /** Conf key for the max file size after which we split the region */
309   public static final String HREGION_MAX_FILESIZE =
310       "hbase.hregion.max.filesize";
311 
312   /** Default maximum file size */
313   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
314 
315   /**
316    * Max size of single row for Get's or Scan's without in-row scanning flag set.
317    */
318   public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
319 
320   /**
321    * Default max row size (1 Gb).
322    */
323   public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
324 
325   /**
326    * The max number of threads used for opening and closing stores or store
327    * files in parallel
328    */
329   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
330     "hbase.hstore.open.and.close.threads.max";
331 
332   /**
333    * The default number for the max number of threads used for opening and
334    * closing stores or store files in parallel
335    */
336   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
337 
338 
339   /** Conf key for the memstore size at which we flush the memstore */
340   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
341       "hbase.hregion.memstore.flush.size";
342 
343   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
344       "hbase.hregion.edits.replay.skip.errors";
345 
346   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
347       false;
348 
349   /** Maximum value length, enforced on KeyValue construction */
350   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
351 
352   /** name of the file for unique cluster ID */
353   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
354 
355   /** Default value for cluster ID */
356   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
357 
358   /** Parameter name for # days to keep MVCC values during a major compaction */
359   public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
360   /** At least to keep MVCC values in hfiles for 5 days */
361   public static final int MIN_KEEP_SEQID_PERIOD = 5;
362 
363   // Always store the location of the root table's HRegion.
364   // This HRegion is never split.
365 
366   // region name = table + startkey + regionid. This is the row key.
367   // each row in the root and meta tables describes exactly 1 region
368   // Do we ever need to know all the information that we are storing?
369 
370   // Note that the name of the root table starts with "-" and the name of the
371   // meta table starts with "." Why? it's a trick. It turns out that when we
372   // store region names in memory, we use a SortedMap. Since "-" sorts before
373   // "." (and since no other table name can start with either of these
374   // characters, the root region will always be the first entry in such a Map,
375   // followed by all the meta regions (which will be ordered by their starting
376   // row key as well), followed by all user tables. So when the Master is
377   // choosing regions to assign, it will always choose the root region first,
378   // followed by the meta regions, followed by user regions. Since the root
379   // and meta regions always need to be on-line, this ensures that they will
380   // be the first to be reassigned if the server(s) they are being served by
381   // should go down.
382 
383 
384   /** The hbase:meta table's name. */
385   @Deprecated  // for compat from 0.94 -> 0.96.
386   public static final byte[] META_TABLE_NAME = TableName.META_TABLE_NAME.getName();
387 
388   public static final String BASE_NAMESPACE_DIR = "data";
389 
390   /** delimiter used between portions of a region name */
391   public static final int META_ROW_DELIMITER = ',';
392 
393   /** The catalog family as a string*/
394   public static final String CATALOG_FAMILY_STR = "info";
395 
396   /** The catalog family */
397   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
398 
399   /** The RegionInfo qualifier as a string */
400   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
401 
402   /** The regioninfo column qualifier */
403   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
404 
405   /** The server column qualifier */
406   public static final String SERVER_QUALIFIER_STR = "server";
407   /** The server column qualifier */
408   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes(SERVER_QUALIFIER_STR);
409 
410   /** The startcode column qualifier */
411   public static final String STARTCODE_QUALIFIER_STR = "serverstartcode";
412   /** The startcode column qualifier */
413   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes(STARTCODE_QUALIFIER_STR);
414 
415   /** The open seqnum column qualifier */
416   public static final String SEQNUM_QUALIFIER_STR = "seqnumDuringOpen";
417   /** The open seqnum column qualifier */
418   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes(SEQNUM_QUALIFIER_STR);
419 
420   /** The state column qualifier */
421   public static final String STATE_QUALIFIER_STR = "state";
422 
423   public static final byte [] STATE_QUALIFIER = Bytes.toBytes(STATE_QUALIFIER_STR);
424 
425   /**
426    * The serverName column qualifier. Its the server where the region is
427    * transitioning on, while column server is the server where the region is
428    * opened on. They are the same when the region is in state OPEN.
429    */
430   public static final String SERVERNAME_QUALIFIER_STR = "sn";
431 
432   public static final byte [] SERVERNAME_QUALIFIER = Bytes.toBytes(SERVERNAME_QUALIFIER_STR);
433 
434   /** The lower-half split region column qualifier */
435   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
436 
437   /** The upper-half split region column qualifier */
438   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
439 
440   /** The lower-half merge region column qualifier */
441   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
442 
443   /** The upper-half merge region column qualifier */
444   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
445 
446   /**
447    * The meta table version column qualifier.
448    * We keep current version of the meta table in this column in <code>-ROOT-</code>
449    * table: i.e. in the 'info:v' column.
450    */
451   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
452 
453   /**
454    * The current version of the meta table.
455    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
456    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
457    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
458    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
459    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
460    * byte[] serialization from Writables to Protobuf.
461    * See HRegionInfo.VERSION
462    */
463   public static final short META_VERSION = 1;
464 
465   // Other constants
466 
467   /**
468    * An empty instance.
469    */
470   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
471 
472   /**
473    * Used by scanners, etc when they want to start at the beginning of a region
474    */
475   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
476 
477   /**
478    * Last row in a table.
479    */
480   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
481 
482   /**
483     * Used by scanners and others when they're trying to detect the end of a
484     * table
485     */
486   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
487 
488   /**
489    * Max length a row can have because of the limitation in TFile.
490    */
491   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
492 
493   /**
494    * Timestamp to use when we want to refer to the latest cell.
495    * This is the timestamp sent by clients when no timestamp is specified on
496    * commit.
497    */
498   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
499 
500   /**
501    * Timestamp to use when we want to refer to the oldest cell.
502    */
503   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
504 
505   /**
506    * LATEST_TIMESTAMP in bytes form
507    */
508   public static final byte [] LATEST_TIMESTAMP_BYTES = {
509     // big-endian
510     (byte) (LATEST_TIMESTAMP >>> 56),
511     (byte) (LATEST_TIMESTAMP >>> 48),
512     (byte) (LATEST_TIMESTAMP >>> 40),
513     (byte) (LATEST_TIMESTAMP >>> 32),
514     (byte) (LATEST_TIMESTAMP >>> 24),
515     (byte) (LATEST_TIMESTAMP >>> 16),
516     (byte) (LATEST_TIMESTAMP >>> 8),
517     (byte) LATEST_TIMESTAMP,
518   };
519 
520   /**
521    * Define for 'return-all-versions'.
522    */
523   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
524 
525   /**
526    * Unlimited time-to-live.
527    */
528 //  public static final int FOREVER = -1;
529   public static final int FOREVER = Integer.MAX_VALUE;
530 
531   /**
532    * Seconds in a week
533    */
534   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
535 
536   /**
537    * Seconds in a day, hour and minute
538    */
539   public static final int DAY_IN_SECONDS = 24 * 60 * 60;
540   public static final int HOUR_IN_SECONDS = 60 * 60;
541   public static final int MINUTE_IN_SECONDS = 60;
542 
543   //TODO: although the following are referenced widely to format strings for
544   //      the shell. They really aren't a part of the public API. It would be
545   //      nice if we could put them somewhere where they did not need to be
546   //      public. They could have package visibility
547   public static final String NAME = "NAME";
548   public static final String VERSIONS = "VERSIONS";
549   public static final String IN_MEMORY = "IN_MEMORY";
550   public static final String METADATA = "METADATA";
551   public static final String CONFIGURATION = "CONFIGURATION";
552 
553   /**
554    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
555    * run out of array items.  Retries beyond this use the last number in the array.  So, for
556    * example, if hbase.client.pause is 1 second, and maximum retries count
557    * hbase.client.retries.number is 10, we will retry at the following intervals:
558    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
559    * With 100ms, a back-off of 200 means 20s
560    */
561   public static final int RETRY_BACKOFF[] = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
562 
563   public static final String REGION_IMPL = "hbase.hregion.impl";
564 
565   /** modifyTable op for replacing the table descriptor */
566   @InterfaceAudience.Private
567   public static enum Modify {
568     CLOSE_REGION,
569     TABLE_COMPACT,
570     TABLE_FLUSH,
571     TABLE_MAJOR_COMPACT,
572     TABLE_SET_HTD,
573     TABLE_SPLIT
574   }
575 
576   /**
577    * Scope tag for locally scoped data.
578    * This data will not be replicated.
579    */
580   public static final int REPLICATION_SCOPE_LOCAL = 0;
581 
582   /**
583    * Scope tag for globally scoped data.
584    * This data will be replicated to all peers.
585    */
586   public static final int REPLICATION_SCOPE_GLOBAL = 1;
587 
588   /**
589    * Default cluster ID, cannot be used to identify a cluster so a key with
590    * this value means it wasn't meant for replication.
591    */
592   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
593 
594     /**
595      * Parameter name for maximum number of bytes returned when calling a
596      * scanner's next method.
597      */
598   public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
599       "hbase.client.scanner.max.result.size";
600 
601   /**
602    * Maximum number of bytes returned when calling a scanner's next method.
603    * Note that when a single row is larger than this limit the row is still
604    * returned completely.
605    *
606    * The default value is 2MB.
607    */
608   public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
609 
610   /**
611    * Parameter name for client pause value, used mostly as value to wait
612    * before running a retry of a failed get, region lookup, etc.
613    */
614   public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
615 
616   /**
617    * Default value of {@link #HBASE_CLIENT_PAUSE}.
618    */
619   public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
620 
621   /**
622    * The maximum number of concurrent connections the client will maintain.
623    */
624   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
625 
626   /**
627    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
628    */
629   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
630 
631   /**
632    * The maximum number of concurrent connections the client will maintain to a single
633    * RegionServer.
634    */
635   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
636 
637   /**
638    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
639    */
640   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
641 
642   /**
643    * The maximum number of concurrent connections the client will maintain to a single
644    * Region.
645    */
646   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
647 
648   /**
649    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
650    */
651   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
652 
653   /**
654    * Parameter name for server pause value, used mostly as value to wait before
655    * running a retry of a failed operation.
656    */
657   public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
658 
659   /**
660    * Default value of {@link #HBASE_SERVER_PAUSE}.
661    */
662   public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
663 
664   /**
665    * Parameter name for maximum retries, used as maximum for all retryable
666    * operations such as fetching of the root region from root region server,
667    * getting a cell's value, starting a row update, etc.
668    */
669   public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
670 
671   /**
672    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
673    */
674   public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
675 
676   /**
677    * Parameter name to set the default scanner caching for all clients.
678    */
679   public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
680 
681   /**
682    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
683    */
684   public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = 100;
685 
686   /**
687    * Parameter name for number of versions, kept by meta table.
688    */
689   public static String HBASE_META_VERSIONS = "hbase.meta.versions";
690 
691   /**
692    * Default value of {@link #HBASE_META_VERSIONS}.
693    */
694   public static int DEFAULT_HBASE_META_VERSIONS = 10;
695 
696   /**
697    * Parameter name for number of versions, kept by meta table.
698    */
699   public static String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
700 
701   /**
702    * Default value of {@link #HBASE_META_BLOCK_SIZE}.
703    */
704   public static int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
705 
706   /**
707    * Parameter name for number of rows that will be fetched when calling next on
708    * a scanner if it is not served from memory. Higher caching values will
709    * enable faster scanners but will eat up more memory and some calls of next
710    * may take longer and longer times when the cache is empty.
711    */
712   public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
713 
714   /**
715    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
716    */
717   public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
718 
719   /**
720    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
721    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
722    * for all intents and purposes, are the same except for their instance ids, then they will not be
723    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
724    * even if the instance ids are the same, it could result in non-shared
725    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
726    * differ.
727    */
728   public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
729 
730   /**
731    * The client scanner timeout period in milliseconds.
732    */
733   public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
734 
735   /**
736    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
737    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
738    */
739   @Deprecated
740   public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
741       "hbase.regionserver.lease.period";
742 
743   /**
744    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
745    */
746   public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
747 
748   /**
749    * timeout for each RPC
750    */
751   public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
752 
753   /**
754    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
755    */
756   public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
757 
758   /**
759    * timeout for short operation RPC
760    */
761   public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY = "hbase.rpc.shortoperation.timeout";
762 
763   /**
764    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
765    */
766   public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
767 
768   /**
769    * Value indicating the server name was saved with no sequence number.
770    */
771   public static final long NO_SEQNUM = -1;
772 
773 
774   /*
775    * cluster replication constants.
776    */
777   public static final String
778       REPLICATION_ENABLE_KEY = "hbase.replication";
779   public static final boolean
780       REPLICATION_ENABLE_DEFAULT = true;
781   public static final String
782       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
783   public static final String
784       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
785   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
786     "org.apache.hadoop.hbase.replication.regionserver.Replication";
787 
788   /** HBCK special code name used as server name when manipulating ZK nodes */
789   public static final String HBCK_CODE_NAME = "HBCKServerName";
790 
791   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
792     "hbase.regionserver.hostname.seen.by.master";
793 
794   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
795       "hbase.master.logcleaner.plugins";
796 
797   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
798     "hbase.regionserver.region.split.policy";
799 
800   /** Whether nonces are enabled; default is true. */
801   public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
802 
803   /**
804    * Configuration key for the size of the block cache
805    */
806   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
807     "hfile.block.cache.size";
808 
809   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
810 
811   /*
812     * Minimum percentage of free heap necessary for a successful cluster startup.
813     */
814   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
815 
816   public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile
817       ("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
818   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
819       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
820 
821   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
822   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
823   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
824       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
825       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
826 
827   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
828   public static final int SOCKET_RETRY_WAIT_MS = 200;
829 
830   /** Host name of the local machine */
831   public static final String LOCALHOST = "localhost";
832 
833   /**
834    * If this parameter is set to true, then hbase will read
835    * data and then verify checksums. Checksum verification
836    * inside hdfs will be switched off.  However, if the hbase-checksum
837    * verification fails, then it will switch back to using
838    * hdfs checksums for verifiying data that is being read from storage.
839    *
840    * If this parameter is set to false, then hbase will not
841    * verify any checksums, instead it will depend on checksum verification
842    * being done in the hdfs client.
843    */
844   public static final String HBASE_CHECKSUM_VERIFICATION =
845       "hbase.regionserver.checksum.verify";
846 
847   public static final String LOCALHOST_IP = "127.0.0.1";
848 
849   /** Conf key that enables unflushed WAL edits directly being replayed to region servers */
850   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
851   /**
852    * Default 'distributed log replay' as true since hbase 1.1 (HBASE-12577)
853    */
854   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = false;
855   public static final String DISALLOW_WRITES_IN_RECOVERING =
856       "hbase.regionserver.disallow.writes.when.recovering";
857   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
858 
859   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
860   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
861 
862   /*
863    * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
864    * -1  => Disable aborting
865    * 0   => Abort if even a single handler has died
866    * 0.x => Abort only when this percent of handlers have died
867    * 1   => Abort only all of the handers have died
868    */
869   public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
870 		  "hbase.regionserver.handler.abort.on.error.percent";
871   public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
872 
873   //High priority handlers to deal with admin requests and system table operation requests
874   public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
875       "hbase.regionserver.metahandler.count";
876   public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 10;
877 
878   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
879       "hbase.regionserver.replication.handler.count";
880   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
881 
882   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
883   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
884 
885   /** Conf key that specifies timeout value to wait for a region ready */
886   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
887       "hbase.master.log.replay.wait.region.timeout";
888 
889   /**
890    * The name of the configuration parameter that specifies
891    * the number of bytes in a newly created checksum chunk.
892    */
893   public static final String BYTES_PER_CHECKSUM =
894       "hbase.hstore.bytes.per.checksum";
895 
896   /**
897    * The name of the configuration parameter that specifies
898    * the name of an algorithm that is used to compute checksums
899    * for newly created blocks.
900    */
901   public static final String CHECKSUM_TYPE_NAME =
902       "hbase.hstore.checksum.algorithm";
903 
904   /** Enable file permission modification from standard hbase */
905   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
906   /** File permission umask to use when creating hbase data files */
907   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
908 
909   /** Configuration name of WAL Compression */
910   public static final String ENABLE_WAL_COMPRESSION =
911     "hbase.regionserver.wal.enablecompression";
912 
913   /** Region in Transition metrics threshold time */
914   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
915 
916   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
917 
918   /**
919    * The byte array represents for NO_NEXT_INDEXED_KEY;
920    * The actual value is irrelevant because this is always compared by reference.
921    */
922   public static final byte [] NO_NEXT_INDEXED_KEY = Bytes.toBytes("NO_NEXT_INDEXED_KEY");
923   /** delimiter used between portions of a region name */
924   public static final int DELIMITER = ',';
925   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
926       "hbase.config.read.zookeeper.config";
927   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
928       false;
929 
930   /**
931    * QOS attributes: these attributes are used to demarcate RPC call processing
932    * by different set of handlers. For example, HIGH_QOS tagged methods are
933    * handled by high priority handlers.
934    */
935   public static final int NORMAL_QOS = 0;
936   public static final int QOS_THRESHOLD = 10;
937   public static final int HIGH_QOS = 200;
938   public static final int REPLICATION_QOS = 5; // normal_QOS < replication_QOS < high_QOS
939   public static final int REPLAY_QOS = 6; // REPLICATION_QOS < REPLAY_QOS < high_QOS
940   public static final int ADMIN_QOS = 100; // QOS_THRESHOLD < ADMIN_QOS < high_QOS
941   public static final int SYSTEMTABLE_QOS = HIGH_QOS;
942 
943   /** Directory under /hbase where archived hfiles are stored */
944   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
945 
946   /**
947    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
948    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
949    * uni-directional.
950    */
951   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
952 
953   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
954   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
955 
956   /** Temporary directory used for table creation and deletion */
957   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
958   /**
959    * The period (in milliseconds) between computing region server point in time metrics
960    */
961   public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
962   public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
963   /** Directories that are not HBase table directories */
964   public static final List<String> HBASE_NON_TABLE_DIRS =
965     Collections.unmodifiableList(Arrays.asList(new String[] {
966       HBCK_SIDELINEDIR_NAME, HBASE_TEMP_DIRECTORY, MIGRATION_NAME
967     }));
968 
969   /** Directories that are not HBase user table directories */
970   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
971     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
972       new String[] { TableName.META_TABLE_NAME.getNameAsString() },
973       HBASE_NON_TABLE_DIRS.toArray())));
974 
975   /** Health script related settings. */
976   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
977   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
978   public static final String HEALTH_CHORE_WAKE_FREQ =
979       "hbase.node.health.script.frequency";
980   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
981   /**
982    * The maximum number of health check failures a server can encounter consecutively.
983    */
984   public static final String HEALTH_FAILURE_THRESHOLD =
985       "hbase.node.health.failure.threshold";
986   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
987 
988 
989   /**
990    * Setting to activate, or not, the publication of the status by the master. Default
991    *  notification is by a multicast message.
992    */
993   public static final String STATUS_PUBLISHED = "hbase.status.published";
994   public static final boolean STATUS_PUBLISHED_DEFAULT = false;
995 
996   /**
997    * IP to use for the multicast status messages between the master and the clients.
998    * The default address is chosen as one among others within the ones suitable for multicast
999    * messages.
1000    */
1001   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
1002   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
1003 
1004   /**
1005    * The address to use for binding the local socket for receiving multicast. Defaults to
1006    * 0.0.0.0.
1007    * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
1008    */
1009   public static final String STATUS_MULTICAST_BIND_ADDRESS = "hbase.status.multicast.bind.address.ip";
1010   public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
1011 
1012   /**
1013    * The port to use for the multicast messages.
1014    */
1015   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
1016   public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
1017 
1018   public static final long NO_NONCE = 0;
1019 
1020   /** Configuration key for the crypto algorithm provider, a class name */
1021   public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
1022 
1023   /** Configuration key for the crypto key provider, a class name */
1024   public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
1025 
1026   /** Configuration key for the crypto key provider parameters */
1027   public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
1028       "hbase.crypto.keyprovider.parameters";
1029 
1030   /** Configuration key for the name of the master key for the cluster, a string */
1031   public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
1032 
1033   /** Configuration key for the name of the alternate master key for the cluster, a string */
1034   public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
1035     "hbase.crypto.master.alternate.key.name";
1036 
1037   /** Configuration key for the algorithm to use when encrypting the WAL, a string */
1038   public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
1039 
1040   /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
1041   public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
1042 
1043   /** Configuration key for enabling WAL encryption, a boolean */
1044   public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
1045 
1046   /** Configuration key for setting RPC codec class name */
1047   public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
1048 
1049   /** Configuration key for setting replication codec class name */
1050   public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
1051 
1052   /** Config for pluggable consensus provider */
1053   public static final String HBASE_COORDINATED_STATE_MANAGER_CLASS =
1054     "hbase.coordinated.state.manager.class";
1055 
1056   /** Configuration key for SplitLog manager timeout */
1057   public static final String HBASE_SPLITLOG_MANAGER_TIMEOUT = "hbase.splitlog.manager.timeout";
1058 
1059   /**
1060    * Configuration keys for Bucket cache
1061    */
1062   // TODO moving these bucket cache implementation specific configs to this level is violation of
1063   // encapsulation. But as these has to be referred from hbase-common and bucket cache
1064   // sits in hbase-server, there were no other go! Can we move the cache implementation to
1065   // hbase-common?
1066 
1067   /**
1068    * Current ioengine options in include: heap, offheap and file:PATH (where PATH is the path
1069    * to the file that will host the file-based cache.  See BucketCache#getIOEngineFromName() for
1070    * list of supported ioengine options.
1071    * <p>Set this option and a non-zero {@link #BUCKET_CACHE_SIZE_KEY} to enable bucket cache.
1072    */
1073   public static final String BUCKET_CACHE_IOENGINE_KEY = "hbase.bucketcache.ioengine";
1074 
1075   /**
1076    * When using bucket cache, this is a float that EITHER represents a percentage of total heap
1077    * memory size to give to the cache (if < 1.0) OR, it is the capacity in megabytes of the cache.
1078    */
1079   public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1080 
1081   /**
1082    * HConstants for fast fail on the client side follow
1083    */
1084   /**
1085    * Config for enabling/disabling the fast fail mode.
1086    */
1087   public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1088       "hbase.client.fast.fail.mode.enabled";
1089 
1090   public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT =
1091       false;
1092 
1093   public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1094       "hbase.client.fastfail.threshold";
1095 
1096   public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT =
1097       60000;
1098 
1099   public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1100       "hbase.client.fast.fail.cleanup.duration";
1101 
1102   public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT =
1103       600000;
1104 
1105   public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1106       "hbase.client.fast.fail.interceptor.impl";
1107 
1108   /** Config key for if the server should send backpressure and if the client should listen to
1109    * that backpressure from the server */
1110   public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1111   public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1112 
1113   public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1114       "hbase.heap.occupancy.low_water_mark";
1115   public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1116   public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1117       "hbase.heap.occupancy.high_water_mark";
1118   public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1119 
1120   private HConstants() {
1121     // Can't be instantiated with this ctor.
1122   }
1123 }