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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   /** Config for pluggable region normalizer */
127   public static final String HBASE_MASTER_NORMALIZER_CLASS =
128     "hbase.master.normalizer.class";
129 
130   /** Config for enabling/disabling pluggable region normalizer */
131   public static final String HBASE_NORMALIZER_ENABLED =
132     "hbase.normalizer.enabled";
133 
134   /** Cluster is standalone or pseudo-distributed */
135   public static final boolean CLUSTER_IS_LOCAL = false;
136 
137   /** Cluster is fully-distributed */
138   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
139 
140   /** Default value for cluster distributed mode */
141   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
142 
143   /** default host address */
144   public static final String DEFAULT_HOST = "0.0.0.0";
145 
146   /** Parameter name for port master listens on. */
147   public static final String MASTER_PORT = "hbase.master.port";
148 
149   /** default port that the master listens on */
150   public static final int DEFAULT_MASTER_PORT = 16000;
151 
152   /** default port for master web api */
153   public static final int DEFAULT_MASTER_INFOPORT = 16010;
154 
155   /** Configuration key for master web API port */
156   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
157 
158   /** Parameter name for the master type being backup (waits for primary to go inactive). */
159   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
160 
161   /**
162    * by default every master is a possible primary master unless the conf explicitly overrides it
163    */
164   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
165 
166   /** Name of ZooKeeper quorum configuration parameter. */
167   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
168 
169   /** Common prefix of ZooKeeper configuration properties */
170   public static final String ZK_CFG_PROPERTY_PREFIX =
171       "hbase.zookeeper.property.";
172 
173   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
174       ZK_CFG_PROPERTY_PREFIX.length();
175 
176   /**
177    * The ZK client port key in the ZK properties map. The name reflects the
178    * fact that this is not an HBase configuration key.
179    */
180   public static final String CLIENT_PORT_STR = "clientPort";
181 
182   /** Parameter name for the client port that the zookeeper listens on */
183   public static final String ZOOKEEPER_CLIENT_PORT =
184       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
185 
186   /** Default client port that the zookeeper listens on */
187   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
188 
189   /**
190    * Parameter name for the wait time for the recoverable zookeeper
191    */
192   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME =
193       "hbase.zookeeper.recoverable.waittime";
194 
195   /** Default wait time for the recoverable zookeeper */
196   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
197 
198   /** Parameter name for the root dir in ZK for this cluster */
199   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
200 
201   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
202 
203   /**
204    * Parameter name for the limit on concurrent client-side zookeeper
205    * connections
206    */
207   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
208       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
209 
210   /** Parameter name for the ZK data directory */
211   public static final String ZOOKEEPER_DATA_DIR =
212       ZK_CFG_PROPERTY_PREFIX + "dataDir";
213 
214   /** Parameter name for the ZK tick time */
215   public static final String ZOOKEEPER_TICK_TIME =
216       ZK_CFG_PROPERTY_PREFIX + "tickTime";
217 
218   /** Default limit on concurrent client-side zookeeper connections */
219   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
220 
221   /** Configuration key for ZooKeeper session timeout */
222   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
223 
224   /** Default value for ZooKeeper session timeout */
225   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
226 
227   /** Configuration key for whether to use ZK.multi */
228   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
229 
230   /** Parameter name for port region server listens on. */
231   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
232 
233   /** Default port region server listens on. */
234   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
235 
236   /** default port for region server web api */
237   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
238 
239   /** A configuration key for regionserver info port */
240   public static final String REGIONSERVER_INFO_PORT =
241     "hbase.regionserver.info.port";
242 
243   /** A flag that enables automatic selection of regionserver info port */
244   public static final String REGIONSERVER_INFO_PORT_AUTO =
245       REGIONSERVER_INFO_PORT + ".auto";
246 
247   /** Parameter name for what region server implementation to use. */
248   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
249 
250   /** Parameter name for what master implementation to use. */
251   public static final String MASTER_IMPL= "hbase.master.impl";
252 
253   /** Parameter name for what hbase client implementation to use. */
254   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
255 
256   /** Parameter name for how often threads should wake up */
257   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
258 
259   /** Default value for thread wake frequency */
260   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
261 
262   /** Parameter name for how often we should try to write a version file, before failing */
263   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
264 
265   /** Parameter name for how often we should try to write a version file, before failing */
266   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
267 
268   /** Parameter name for how often a region should should perform a major compaction */
269   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
270 
271   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
272   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
273   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
274 
275   /** Parameter name for HBase instance root directory */
276   public static final String HBASE_DIR = "hbase.rootdir";
277 
278   /** Parameter name for HBase client IPC pool type */
279   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
280 
281   /** Parameter name for HBase client IPC pool size */
282   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
283 
284   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
285   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
286 
287   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
288   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
289     "hbase.client.meta.operation.timeout";
290 
291   /** Default HBase client operation timeout, which is tantamount to a blocking call */
292   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = 1200000;
293 
294   /** Used to construct the name of the log directory for a region server */
295   public static final String HREGION_LOGDIR_NAME = "WALs";
296 
297   /** Used to construct the name of the splitlog directory for a region server */
298   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
299 
300   /** Like the previous, but for old logs that are about to be deleted */
301   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
302 
303   public static final String CORRUPT_DIR_NAME = "corrupt";
304 
305   /** Used by HBCK to sideline backup data */
306   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
307 
308   /** Any artifacts left from migration can be moved here */
309   public static final String MIGRATION_NAME = ".migration";
310 
311   /**
312    * The directory from which co-processor/custom filter jars can be loaded
313    * dynamically by the region servers. This value can be overridden by the
314    * hbase.dynamic.jars.dir config.
315    */
316   public static final String LIB_DIR = "lib";
317 
318   /** Used to construct the name of the compaction directory during compaction */
319   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
320 
321   /** Conf key for the max file size after which we split the region */
322   public static final String HREGION_MAX_FILESIZE =
323       "hbase.hregion.max.filesize";
324 
325   /** Default maximum file size */
326   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
327 
328   /**
329    * Max size of single row for Get's or Scan's without in-row scanning flag set.
330    */
331   public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
332 
333   /**
334    * Default max row size (1 Gb).
335    */
336   public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
337 
338   /**
339    * The max number of threads used for opening and closing stores or store
340    * files in parallel
341    */
342   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
343     "hbase.hstore.open.and.close.threads.max";
344 
345   /**
346    * The default number for the max number of threads used for opening and
347    * closing stores or store files in parallel
348    */
349   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
350 
351 
352   /** Conf key for the memstore size at which we flush the memstore */
353   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
354       "hbase.hregion.memstore.flush.size";
355 
356   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
357       "hbase.hregion.edits.replay.skip.errors";
358 
359   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
360       false;
361 
362   /** Maximum value length, enforced on KeyValue construction */
363   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
364 
365   /** name of the file for unique cluster ID */
366   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
367 
368   /** Default value for cluster ID */
369   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
370 
371   /** Parameter name for # days to keep MVCC values during a major compaction */
372   public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
373   /** At least to keep MVCC values in hfiles for 5 days */
374   public static final int MIN_KEEP_SEQID_PERIOD = 5;
375 
376   // Always store the location of the root table's HRegion.
377   // This HRegion is never split.
378 
379   // region name = table + startkey + regionid. This is the row key.
380   // each row in the root and meta tables describes exactly 1 region
381   // Do we ever need to know all the information that we are storing?
382 
383   // Note that the name of the root table starts with "-" and the name of the
384   // meta table starts with "." Why? it's a trick. It turns out that when we
385   // store region names in memory, we use a SortedMap. Since "-" sorts before
386   // "." (and since no other table name can start with either of these
387   // characters, the root region will always be the first entry in such a Map,
388   // followed by all the meta regions (which will be ordered by their starting
389   // row key as well), followed by all user tables. So when the Master is
390   // choosing regions to assign, it will always choose the root region first,
391   // followed by the meta regions, followed by user regions. Since the root
392   // and meta regions always need to be on-line, this ensures that they will
393   // be the first to be reassigned if the server(s) they are being served by
394   // should go down.
395 
396 
397   /**
398    * The hbase:meta table's name.
399    *
400    */
401   @Deprecated  // for compat from 0.94 -> 0.96.
402   public static final byte[] META_TABLE_NAME = TableName.META_TABLE_NAME.getName();
403 
404   public static final String BASE_NAMESPACE_DIR = "data";
405 
406   /** delimiter used between portions of a region name */
407   public static final int META_ROW_DELIMITER = ',';
408 
409   /** The catalog family as a string*/
410   public static final String CATALOG_FAMILY_STR = "info";
411 
412   /** The catalog family */
413   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
414 
415   /** The RegionInfo qualifier as a string */
416   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
417 
418   /** The regioninfo column qualifier */
419   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
420 
421   /** The server column qualifier */
422   public static final String SERVER_QUALIFIER_STR = "server";
423   /** The server column qualifier */
424   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes(SERVER_QUALIFIER_STR);
425 
426   /** The startcode column qualifier */
427   public static final String STARTCODE_QUALIFIER_STR = "serverstartcode";
428   /** The startcode column qualifier */
429   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes(STARTCODE_QUALIFIER_STR);
430 
431   /** The open seqnum column qualifier */
432   public static final String SEQNUM_QUALIFIER_STR = "seqnumDuringOpen";
433   /** The open seqnum column qualifier */
434   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes(SEQNUM_QUALIFIER_STR);
435 
436   /** The state column qualifier */
437   public static final String STATE_QUALIFIER_STR = "state";
438 
439   public static final byte [] STATE_QUALIFIER = Bytes.toBytes(STATE_QUALIFIER_STR);
440 
441   /**
442    * The serverName column qualifier. Its the server where the region is
443    * transitioning on, while column server is the server where the region is
444    * opened on. They are the same when the region is in state OPEN.
445    */
446   public static final String SERVERNAME_QUALIFIER_STR = "sn";
447 
448   public static final byte [] SERVERNAME_QUALIFIER = Bytes.toBytes(SERVERNAME_QUALIFIER_STR);
449 
450   /** The lower-half split region column qualifier */
451   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
452 
453   /** The upper-half split region column qualifier */
454   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
455 
456   /** The lower-half merge region column qualifier */
457   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
458 
459   /** The upper-half merge region column qualifier */
460   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
461 
462   /** The catalog family as a string*/
463   public static final String TABLE_FAMILY_STR = "table";
464 
465   /** The catalog family */
466   public static final byte [] TABLE_FAMILY = Bytes.toBytes(TABLE_FAMILY_STR);
467 
468   /** The serialized table state qualifier */
469   public static final byte[] TABLE_STATE_QUALIFIER = Bytes.toBytes("state");
470 
471 
472   /**
473    * The meta table version column qualifier.
474    * We keep current version of the meta table in this column in <code>-ROOT-</code>
475    * table: i.e. in the 'info:v' column.
476    */
477   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
478 
479   /**
480    * The current version of the meta table.
481    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
482    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
483    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
484    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
485    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
486    * byte[] serialization from Writables to Protobuf.
487    * See HRegionInfo.VERSION
488    */
489   public static final short META_VERSION = 1;
490 
491   // Other constants
492 
493   /**
494    * An empty instance.
495    */
496   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
497 
498   /**
499    * Used by scanners, etc when they want to start at the beginning of a region
500    */
501   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
502 
503   /**
504    * Last row in a table.
505    */
506   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
507 
508   /**
509     * Used by scanners and others when they're trying to detect the end of a
510     * table
511     */
512   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
513 
514   /**
515    * Max length a row can have because of the limitation in TFile.
516    */
517   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
518 
519   /**
520    * Timestamp to use when we want to refer to the latest cell.
521    * This is the timestamp sent by clients when no timestamp is specified on
522    * commit.
523    */
524   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
525 
526   /**
527    * Timestamp to use when we want to refer to the oldest cell.
528    */
529   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
530 
531   /**
532    * LATEST_TIMESTAMP in bytes form
533    */
534   public static final byte [] LATEST_TIMESTAMP_BYTES = {
535     // big-endian
536     (byte) (LATEST_TIMESTAMP >>> 56),
537     (byte) (LATEST_TIMESTAMP >>> 48),
538     (byte) (LATEST_TIMESTAMP >>> 40),
539     (byte) (LATEST_TIMESTAMP >>> 32),
540     (byte) (LATEST_TIMESTAMP >>> 24),
541     (byte) (LATEST_TIMESTAMP >>> 16),
542     (byte) (LATEST_TIMESTAMP >>> 8),
543     (byte) LATEST_TIMESTAMP,
544   };
545 
546   /**
547    * Define for 'return-all-versions'.
548    */
549   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
550 
551   /**
552    * Unlimited time-to-live.
553    */
554 //  public static final int FOREVER = -1;
555   public static final int FOREVER = Integer.MAX_VALUE;
556 
557   /**
558    * Seconds in a week
559    */
560   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
561 
562   /**
563    * Seconds in a day, hour and minute
564    */
565   public static final int DAY_IN_SECONDS = 24 * 60 * 60;
566   public static final int HOUR_IN_SECONDS = 60 * 60;
567   public static final int MINUTE_IN_SECONDS = 60;
568 
569   //TODO: although the following are referenced widely to format strings for
570   //      the shell. They really aren't a part of the public API. It would be
571   //      nice if we could put them somewhere where they did not need to be
572   //      public. They could have package visibility
573   public static final String NAME = "NAME";
574   public static final String VERSIONS = "VERSIONS";
575   public static final String IN_MEMORY = "IN_MEMORY";
576   public static final String METADATA = "METADATA";
577   public static final String CONFIGURATION = "CONFIGURATION";
578 
579   /**
580    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
581    * run out of array items.  Retries beyond this use the last number in the array.  So, for
582    * example, if hbase.client.pause is 1 second, and maximum retries count
583    * hbase.client.retries.number is 10, we will retry at the following intervals:
584    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
585    * With 100ms, a back-off of 200 means 20s
586    */
587   public static final int RETRY_BACKOFF[] = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
588 
589   public static final String REGION_IMPL = "hbase.hregion.impl";
590 
591   /** modifyTable op for replacing the table descriptor */
592   @InterfaceAudience.Private
593   public static enum Modify {
594     CLOSE_REGION,
595     TABLE_COMPACT,
596     TABLE_FLUSH,
597     TABLE_MAJOR_COMPACT,
598     TABLE_SET_HTD,
599     TABLE_SPLIT
600   }
601 
602   /**
603    * Scope tag for locally scoped data.
604    * This data will not be replicated.
605    */
606   public static final int REPLICATION_SCOPE_LOCAL = 0;
607 
608   /**
609    * Scope tag for globally scoped data.
610    * This data will be replicated to all peers.
611    */
612   public static final int REPLICATION_SCOPE_GLOBAL = 1;
613 
614   /**
615    * Default cluster ID, cannot be used to identify a cluster so a key with
616    * this value means it wasn't meant for replication.
617    */
618   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
619 
620   /**
621    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
622    * Controlled by the client.
623    */
624   public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
625       "hbase.client.scanner.max.result.size";
626 
627   /**
628    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
629    * Controlled by the server.
630    */
631   public static final String HBASE_SERVER_SCANNER_MAX_RESULT_SIZE_KEY =
632       "hbase.server.scanner.max.result.size";
633 
634   /**
635    * Maximum number of bytes returned when calling a scanner's next method.
636    * Note that when a single row is larger than this limit the row is still
637    * returned completely.
638    *
639    * The default value is 2MB.
640    */
641   public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
642 
643   /**
644    * Maximum number of bytes returned when calling a scanner's next method.
645    * Note that when a single row is larger than this limit the row is still
646    * returned completely.
647    * Safety setting to protect the region server.
648    *
649    * The default value is 100MB. (a client would rarely request larger chunks on purpose)
650    */
651   public static final long DEFAULT_HBASE_SERVER_SCANNER_MAX_RESULT_SIZE = 100 * 1024 * 1024;
652 
653   /**
654    * Parameter name for client pause value, used mostly as value to wait
655    * before running a retry of a failed get, region lookup, etc.
656    */
657   public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
658 
659   /**
660    * Default value of {@link #HBASE_CLIENT_PAUSE}.
661    */
662   public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
663 
664   /**
665    * The maximum number of concurrent connections the client will maintain.
666    */
667   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
668 
669   /**
670    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
671    */
672   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
673 
674   /**
675    * The maximum number of concurrent connections the client will maintain to a single
676    * RegionServer.
677    */
678   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
679 
680   /**
681    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
682    */
683   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
684 
685   /**
686    * The maximum number of concurrent connections the client will maintain to a single
687    * Region.
688    */
689   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
690 
691   /**
692    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
693    */
694   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
695 
696   /**
697    * Parameter name for server pause value, used mostly as value to wait before
698    * running a retry of a failed operation.
699    */
700   public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
701 
702   /**
703    * Default value of {@link #HBASE_SERVER_PAUSE}.
704    */
705   public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
706 
707   /**
708    * Parameter name for maximum retries, used as maximum for all retryable
709    * operations such as fetching of the root region from root region server,
710    * getting a cell's value, starting a row update, etc.
711    */
712   public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
713 
714   /**
715    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
716    */
717   public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
718 
719   /**
720    * Parameter name to set the default scanner caching for all clients.
721    */
722   public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
723 
724   /**
725    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
726    */
727   public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = Integer.MAX_VALUE;
728 
729   /**
730    * Parameter name for number of rows that will be fetched when calling next on
731    * a scanner if it is not served from memory. Higher caching values will
732    * enable faster scanners but will eat up more memory and some calls of next
733    * may take longer and longer times when the cache is empty.
734    */
735   public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
736 
737   /**
738    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
739    */
740   public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
741 
742   /**
743    * Parameter name for number of versions, kept by meta table.
744    */
745   public static final String HBASE_META_VERSIONS = "hbase.meta.versions";
746 
747   /**
748    * Default value of {@link #HBASE_META_VERSIONS}.
749    */
750   public static final int DEFAULT_HBASE_META_VERSIONS = 3;
751 
752   /**
753    * Parameter name for number of versions, kept by meta table.
754    */
755   public static final String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
756 
757   /**
758    * Default value of {@link #HBASE_META_BLOCK_SIZE}.
759    */
760   public static final int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
761 
762   /**
763    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
764    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
765    * for all intents and purposes, are the same except for their instance ids, then they will not be
766    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
767    * even if the instance ids are the same, it could result in non-shared
768    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
769    * differ.
770    */
771   public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
772 
773   /**
774    * The client scanner timeout period in milliseconds.
775    */
776   public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD =
777       "hbase.client.scanner.timeout.period";
778 
779   /**
780    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
781    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
782    */
783   @Deprecated
784   public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
785       "hbase.regionserver.lease.period";
786 
787   /**
788    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
789    */
790   public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
791 
792   /**
793    * timeout for each RPC
794    */
795   public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
796 
797   /**
798    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
799    */
800   public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
801 
802   /**
803    * timeout for short operation RPC
804    */
805   public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY = "hbase.rpc.shortoperation.timeout";
806 
807   /**
808    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
809    */
810   public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
811 
812   /**
813    * Value indicating the server name was saved with no sequence number.
814    */
815   public static final long NO_SEQNUM = -1;
816 
817 
818   /*
819    * cluster replication constants.
820    */
821   public static final String
822       REPLICATION_ENABLE_KEY = "hbase.replication";
823   public static final boolean
824       REPLICATION_ENABLE_DEFAULT = true;
825   public static final String
826       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
827   public static final String
828       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
829   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
830     "org.apache.hadoop.hbase.replication.regionserver.Replication";
831 
832   /** HBCK special code name used as server name when manipulating ZK nodes */
833   public static final String HBCK_CODE_NAME = "HBCKServerName";
834 
835   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
836     "hbase.regionserver.hostname.seen.by.master";
837 
838   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
839       "hbase.master.logcleaner.plugins";
840 
841   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
842     "hbase.regionserver.region.split.policy";
843 
844   /** Whether nonces are enabled; default is true. */
845   public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
846 
847   /**
848    * Configuration key for the size of the block cache
849    */
850   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
851     "hfile.block.cache.size";
852 
853   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
854 
855   /*
856     * Minimum percentage of free heap necessary for a successful cluster startup.
857     */
858   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
859 
860   public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile
861       ("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
862   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
863       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
864 
865   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
866   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
867   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
868       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
869       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
870 
871   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
872   public static final int SOCKET_RETRY_WAIT_MS = 200;
873 
874   /** Host name of the local machine */
875   public static final String LOCALHOST = "localhost";
876 
877   /**
878    * If this parameter is set to true, then hbase will read
879    * data and then verify checksums. Checksum verification
880    * inside hdfs will be switched off.  However, if the hbase-checksum
881    * verification fails, then it will switch back to using
882    * hdfs checksums for verifiying data that is being read from storage.
883    *
884    * If this parameter is set to false, then hbase will not
885    * verify any checksums, instead it will depend on checksum verification
886    * being done in the hdfs client.
887    */
888   public static final String HBASE_CHECKSUM_VERIFICATION =
889       "hbase.regionserver.checksum.verify";
890 
891   public static final String LOCALHOST_IP = "127.0.0.1";
892 
893   /** Conf key that enables unflushed WAL edits directly being replayed to region servers */
894   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
895   /**
896    * Default 'distributed log replay' as true since hbase 0.99.0
897    */
898   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = true;
899   public static final String DISALLOW_WRITES_IN_RECOVERING =
900       "hbase.regionserver.disallow.writes.when.recovering";
901   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
902 
903   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
904   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
905 
906   /*
907    * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
908    * -1  => Disable aborting
909    * 0   => Abort if even a single handler has died
910    * 0.x => Abort only when this percent of handlers have died
911    * 1   => Abort only all of the handers have died
912    */
913   public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
914 		  "hbase.regionserver.handler.abort.on.error.percent";
915   public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
916 
917   //High priority handlers to deal with admin requests and system table operation requests
918   public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
919       "hbase.regionserver.metahandler.count";
920   public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 20;
921 
922   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
923       "hbase.regionserver.replication.handler.count";
924   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
925 
926   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
927   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
928 
929   /** Conf key that specifies timeout value to wait for a region ready */
930   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
931       "hbase.master.log.replay.wait.region.timeout";
932 
933   /** Conf key for enabling meta replication */
934   public static final String USE_META_REPLICAS = "hbase.meta.replicas.use";
935   public static final boolean DEFAULT_USE_META_REPLICAS = false;
936   public static final String META_REPLICAS_NUM = "hbase.meta.replica.count";
937   public static final int DEFAULT_META_REPLICA_NUM = 1;
938 
939   /**
940    * The name of the configuration parameter that specifies
941    * the number of bytes in a newly created checksum chunk.
942    */
943   public static final String BYTES_PER_CHECKSUM =
944       "hbase.hstore.bytes.per.checksum";
945 
946   /**
947    * The name of the configuration parameter that specifies
948    * the name of an algorithm that is used to compute checksums
949    * for newly created blocks.
950    */
951   public static final String CHECKSUM_TYPE_NAME =
952       "hbase.hstore.checksum.algorithm";
953 
954   /** Enable file permission modification from standard hbase */
955   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
956   /** File permission umask to use when creating hbase data files */
957   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
958 
959   /** Configuration name of WAL Compression */
960   public static final String ENABLE_WAL_COMPRESSION =
961     "hbase.regionserver.wal.enablecompression";
962 
963   /** Configuration name of WAL storage policy
964    * Valid values are:
965    *  NONE: no preference in destination of block replicas
966    *  ONE_SSD: place only one block replica in SSD and the remaining in default storage
967    *  and ALL_SSD: place all block replicas on SSD
968    *
969    * See http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/ArchivalStorage.html*/
970   public static final String WAL_STORAGE_POLICY = "hbase.wal.storage.policy";
971   public static final String DEFAULT_WAL_STORAGE_POLICY = "NONE";
972 
973   /** Region in Transition metrics threshold time */
974   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
975 
976   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
977 
978   /**
979    * The byte array represents for NO_NEXT_INDEXED_KEY;
980    * The actual value is irrelevant because this is always compared by reference.
981    */
982   public static final Cell NO_NEXT_INDEXED_KEY = new KeyValue();
983   /** delimiter used between portions of a region name */
984   public static final int DELIMITER = ',';
985 
986   /**
987    * QOS attributes: these attributes are used to demarcate RPC call processing
988    * by different set of handlers. For example, HIGH_QOS tagged methods are
989    * handled by high priority handlers.
990    */
991   // normal_QOS < QOS_threshold < replication_QOS < replay_QOS < admin_QOS < high_QOS
992   public static final int NORMAL_QOS = 0;
993   public static final int QOS_THRESHOLD = 10;
994   public static final int HIGH_QOS = 200;
995   public static final int REPLICATION_QOS = 5;
996   public static final int REPLAY_QOS = 6;
997   public static final int ADMIN_QOS = 100;
998   public static final int SYSTEMTABLE_QOS = HIGH_QOS;
999 
1000   /** Directory under /hbase where archived hfiles are stored */
1001   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
1002 
1003   /**
1004    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
1005    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
1006    * uni-directional.
1007    */
1008   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
1009 
1010   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
1011   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
1012 
1013   /** Temporary directory used for table creation and deletion */
1014   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
1015   /**
1016    * The period (in milliseconds) between computing region server point in time metrics
1017    */
1018   public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
1019   public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
1020   /** Directories that are not HBase table directories */
1021   public static final List<String> HBASE_NON_TABLE_DIRS =
1022     Collections.unmodifiableList(Arrays.asList(new String[] {
1023       HBCK_SIDELINEDIR_NAME, HBASE_TEMP_DIRECTORY, MIGRATION_NAME
1024     }));
1025 
1026   /** Directories that are not HBase user table directories */
1027   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
1028     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
1029       new String[] { TableName.META_TABLE_NAME.getNameAsString() },
1030       HBASE_NON_TABLE_DIRS.toArray())));
1031 
1032   /** Health script related settings. */
1033   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
1034   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
1035   public static final String HEALTH_CHORE_WAKE_FREQ =
1036       "hbase.node.health.script.frequency";
1037   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
1038   /**
1039    * The maximum number of health check failures a server can encounter consecutively.
1040    */
1041   public static final String HEALTH_FAILURE_THRESHOLD =
1042       "hbase.node.health.failure.threshold";
1043   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
1044 
1045 
1046   /**
1047    * Setting to activate, or not, the publication of the status by the master. Default
1048    *  notification is by a multicast message.
1049    */
1050   public static final String STATUS_PUBLISHED = "hbase.status.published";
1051   public static final boolean STATUS_PUBLISHED_DEFAULT = false;
1052 
1053   /**
1054    * IP to use for the multicast status messages between the master and the clients.
1055    * The default address is chosen as one among others within the ones suitable for multicast
1056    * messages.
1057    */
1058   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
1059   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
1060 
1061   /**
1062    * The address to use for binding the local socket for receiving multicast. Defaults to
1063    * 0.0.0.0.
1064    * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
1065    */
1066   public static final String STATUS_MULTICAST_BIND_ADDRESS = "hbase.status.multicast.bind.address.ip";
1067   public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
1068 
1069   /**
1070    * The port to use for the multicast messages.
1071    */
1072   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
1073   public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
1074 
1075   public static final long NO_NONCE = 0;
1076 
1077   /** Default cipher for encryption */
1078   public static final String CIPHER_AES = "AES";
1079 
1080   /** Configuration key for the crypto algorithm provider, a class name */
1081   public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
1082 
1083   /** Configuration key for the crypto key provider, a class name */
1084   public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
1085 
1086   /** Configuration key for the crypto key provider parameters */
1087   public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
1088       "hbase.crypto.keyprovider.parameters";
1089 
1090   /** Configuration key for the name of the master key for the cluster, a string */
1091   public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
1092 
1093   /** Configuration key for the name of the alternate master key for the cluster, a string */
1094   public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
1095     "hbase.crypto.master.alternate.key.name";
1096 
1097   /** Configuration key for the algorithm to use when encrypting the WAL, a string */
1098   public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
1099 
1100   /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
1101   public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
1102 
1103   /** Configuration key for the algorithm used for creating jks key, a string */
1104   public static final String CRYPTO_KEY_ALGORITHM_CONF_KEY = "hbase.crypto.key.algorithm";
1105 
1106   /** Configuration key for the name of the alternate cipher algorithm for the cluster, a string */
1107   public static final String CRYPTO_ALTERNATE_KEY_ALGORITHM_CONF_KEY =
1108       "hbase.crypto.alternate.key.algorithm";
1109 
1110   /** Configuration key for enabling WAL encryption, a boolean */
1111   public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
1112 
1113   /** Configuration key for setting RPC codec class name */
1114   public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
1115 
1116   /** Configuration key for setting replication codec class name */
1117   public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
1118 
1119   /** Config for pluggable consensus provider */
1120   public static final String HBASE_COORDINATED_STATE_MANAGER_CLASS =
1121     "hbase.coordinated.state.manager.class";
1122 
1123   /** Configuration key for SplitLog manager timeout */
1124   public static final String HBASE_SPLITLOG_MANAGER_TIMEOUT = "hbase.splitlog.manager.timeout";
1125 
1126   /**
1127    * Configuration keys for Bucket cache
1128    */
1129   // TODO moving these bucket cache implementation specific configs to this level is violation of
1130   // encapsulation. But as these has to be referred from hbase-common and bucket cache
1131   // sits in hbase-server, there were no other go! Can we move the cache implementation to
1132   // hbase-common?
1133 
1134   /**
1135    * Current ioengine options in include: heap, offheap and file:PATH (where PATH is the path
1136    * to the file that will host the file-based cache.  See BucketCache#getIOEngineFromName() for
1137    * list of supported ioengine options.
1138    * <p>Set this option and a non-zero {@link #BUCKET_CACHE_SIZE_KEY} to enable bucket cache.
1139    */
1140   public static final String BUCKET_CACHE_IOENGINE_KEY = "hbase.bucketcache.ioengine";
1141 
1142   /**
1143    * When using bucket cache, this is a float that EITHER represents a percentage of total heap
1144    * memory size to give to the cache (if &lt; 1.0) OR, it is the capacity in
1145    * megabytes of the cache.
1146    */
1147   public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1148 
1149   /**
1150    * HConstants for fast fail on the client side follow
1151    */
1152   /**
1153    * Config for enabling/disabling the fast fail mode.
1154    */
1155   public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1156       "hbase.client.fast.fail.mode.enabled";
1157 
1158   public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT =
1159       false;
1160 
1161   public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1162       "hbase.client.fastfail.threshold";
1163 
1164   public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT =
1165       60000;
1166 
1167   public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1168       "hbase.client.fast.fail.cleanup.duration";
1169 
1170   public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT =
1171       600000;
1172 
1173   public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1174       "hbase.client.fast.fail.interceptor.impl";
1175 
1176   /** Config key for if the server should send backpressure and if the client should listen to
1177    * that backpressure from the server */
1178   public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1179   public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1180 
1181   public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1182       "hbase.heap.occupancy.low_water_mark";
1183   public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1184   public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1185       "hbase.heap.occupancy.high_water_mark";
1186   public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1187 
1188   /**
1189    * The max number of threads used for splitting storefiles in parallel during
1190    * the region split process.
1191    */
1192   public static final String REGION_SPLIT_THREADS_MAX =
1193     "hbase.regionserver.region.split.threads.max";
1194 
1195   private HConstants() {
1196     // Can't be instantiated with this ctor.
1197   }
1198 }