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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 byte[] RPC_HEADER = new byte[] { 'H', 'B', 'a', 's' };
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   /** Parameter name for the ZK tick time */
206   public static final String ZOOKEEPER_TICK_TIME =
207       ZK_CFG_PROPERTY_PREFIX + "tickTime";
208 
209   /** Default limit on concurrent client-side zookeeper connections */
210   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
211 
212   /** Configuration key for ZooKeeper session timeout */
213   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
214 
215   /** Default value for ZooKeeper session timeout */
216   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
217 
218   /** Configuration key for whether to use ZK.multi */
219   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
220 
221   /** Parameter name for port region server listens on. */
222   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
223 
224   /** Default port region server listens on. */
225   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
226 
227   /** default port for region server web api */
228   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
229 
230   /** A configuration key for regionserver info port */
231   public static final String REGIONSERVER_INFO_PORT =
232     "hbase.regionserver.info.port";
233 
234   /** A flag that enables automatic selection of regionserver info port */
235   public static final String REGIONSERVER_INFO_PORT_AUTO =
236       REGIONSERVER_INFO_PORT + ".auto";
237 
238   /** Parameter name for what region server implementation to use. */
239   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
240 
241   /** Parameter name for what master implementation to use. */
242   public static final String MASTER_IMPL= "hbase.master.impl";
243 
244   /** Parameter name for what hbase client implementation to use. */
245   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
246 
247   /** Parameter name for how often threads should wake up */
248   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
249 
250   /** Default value for thread wake frequency */
251   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
252 
253   /** Parameter name for how often we should try to write a version file, before failing */
254   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
255 
256   /** Parameter name for how often we should try to write a version file, before failing */
257   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
258 
259   /** Parameter name for how often a region should should perform a major compaction */
260   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
261 
262   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
263   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
264   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
265 
266   /** Parameter name for HBase instance root directory */
267   public static final String HBASE_DIR = "hbase.rootdir";
268 
269   /** Parameter name for HBase client IPC pool type */
270   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
271 
272   /** Parameter name for HBase client IPC pool size */
273   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
274 
275   /** Parameter name for HBase client operation timeout. */
276   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
277 
278   /** Parameter name for HBase client operation timeout. */
279   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
280     "hbase.client.meta.operation.timeout";
281 
282   /** Default HBase client operation timeout, which is tantamount to a blocking call */
283   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = 1200000;
284 
285   /** Used to construct the name of the log directory for a region server */
286   public static final String HREGION_LOGDIR_NAME = "WALs";
287 
288   /** Used to construct the name of the splitlog directory for a region server */
289   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
290 
291   /** Like the previous, but for old logs that are about to be deleted */
292   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
293 
294   public static final String CORRUPT_DIR_NAME = "corrupt";
295 
296   /** Used by HBCK to sideline backup data */
297   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
298 
299   /** Any artifacts left from migration can be moved here */
300   public static final String MIGRATION_NAME = ".migration";
301 
302   /**
303    * The directory from which co-processor/custom filter jars can be loaded
304    * dynamically by the region servers. This value can be overridden by the
305    * hbase.dynamic.jars.dir config.
306    */
307   public static final String LIB_DIR = "lib";
308 
309   /** Used to construct the name of the compaction directory during compaction */
310   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
311 
312   /** Conf key for the max file size after which we split the region */
313   public static final String HREGION_MAX_FILESIZE =
314       "hbase.hregion.max.filesize";
315 
316   /** Default maximum file size */
317   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
318 
319   /**
320    * Max size of single row for Get's or Scan's without in-row scanning flag set.
321    */
322   public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
323 
324   /**
325    * Default max row size (1 Gb).
326    */
327   public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
328 
329   /**
330    * The max number of threads used for opening and closing stores or store
331    * files in parallel
332    */
333   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
334     "hbase.hstore.open.and.close.threads.max";
335 
336   /**
337    * The default number for the max number of threads used for opening and
338    * closing stores or store files in parallel
339    */
340   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
341 
342   /**
343    * Block updates if memstore has hbase.hregion.memstore.block.multiplier
344    * times hbase.hregion.memstore.flush.size bytes.  Useful preventing
345    * runaway memstore during spikes in update traffic.
346    */
347   public static final String HREGION_MEMSTORE_BLOCK_MULTIPLIER =
348           "hbase.hregion.memstore.block.multiplier";
349 
350   /**
351    * Default value for hbase.hregion.memstore.block.multiplier
352    */
353   public static final int DEFAULT_HREGION_MEMSTORE_BLOCK_MULTIPLIER = 4;
354 
355   /** Conf key for the memstore size at which we flush the memstore */
356   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
357       "hbase.hregion.memstore.flush.size";
358 
359   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
360       "hbase.hregion.edits.replay.skip.errors";
361 
362   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
363       false;
364 
365   /** Maximum value length, enforced on KeyValue construction */
366   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
367 
368   /** name of the file for unique cluster ID */
369   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
370 
371   /** Default value for cluster ID */
372   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
373 
374   /** Parameter name for # days to keep MVCC values during a major compaction */
375   public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
376   /** At least to keep MVCC values in hfiles for 5 days */
377   public static final int MIN_KEEP_SEQID_PERIOD = 5;
378 
379   // Always store the location of the root table's HRegion.
380   // This HRegion is never split.
381 
382   // region name = table + startkey + regionid. This is the row key.
383   // each row in the root and meta tables describes exactly 1 region
384   // Do we ever need to know all the information that we are storing?
385 
386   // Note that the name of the root table starts with "-" and the name of the
387   // meta table starts with "." Why? it's a trick. It turns out that when we
388   // store region names in memory, we use a SortedMap. Since "-" sorts before
389   // "." (and since no other table name can start with either of these
390   // characters, the root region will always be the first entry in such a Map,
391   // followed by all the meta regions (which will be ordered by their starting
392   // row key as well), followed by all user tables. So when the Master is
393   // choosing regions to assign, it will always choose the root region first,
394   // followed by the meta regions, followed by user regions. Since the root
395   // and meta regions always need to be on-line, this ensures that they will
396   // be the first to be reassigned if the server(s) they are being served by
397   // should go down.
398 
399 
400   /** The hbase:meta table's name. */
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   /**
463    * The meta table version column qualifier.
464    * We keep current version of the meta table in this column in <code>-ROOT-</code>
465    * table: i.e. in the 'info:v' column.
466    */
467   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
468 
469   /**
470    * The current version of the meta table.
471    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
472    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
473    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
474    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
475    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
476    * byte[] serialization from Writables to Protobuf.
477    * See HRegionInfo.VERSION
478    */
479   public static final short META_VERSION = 1;
480 
481   // Other constants
482 
483   /**
484    * An empty instance.
485    */
486   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
487 
488   /**
489    * Used by scanners, etc when they want to start at the beginning of a region
490    */
491   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
492 
493   /**
494    * Last row in a table.
495    */
496   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
497 
498   /**
499     * Used by scanners and others when they're trying to detect the end of a
500     * table
501     */
502   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
503 
504   /**
505    * Max length a row can have because of the limitation in TFile.
506    */
507   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
508 
509   /**
510    * Timestamp to use when we want to refer to the latest cell.
511    * This is the timestamp sent by clients when no timestamp is specified on
512    * commit.
513    */
514   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
515 
516   /**
517    * Timestamp to use when we want to refer to the oldest cell.
518    */
519   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
520 
521   /**
522    * LATEST_TIMESTAMP in bytes form
523    */
524   public static final byte [] LATEST_TIMESTAMP_BYTES = {
525     // big-endian
526     (byte) (LATEST_TIMESTAMP >>> 56),
527     (byte) (LATEST_TIMESTAMP >>> 48),
528     (byte) (LATEST_TIMESTAMP >>> 40),
529     (byte) (LATEST_TIMESTAMP >>> 32),
530     (byte) (LATEST_TIMESTAMP >>> 24),
531     (byte) (LATEST_TIMESTAMP >>> 16),
532     (byte) (LATEST_TIMESTAMP >>> 8),
533     (byte) LATEST_TIMESTAMP,
534   };
535 
536   /**
537    * Define for 'return-all-versions'.
538    */
539   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
540 
541   /**
542    * Unlimited time-to-live.
543    */
544 //  public static final int FOREVER = -1;
545   public static final int FOREVER = Integer.MAX_VALUE;
546 
547   /**
548    * Seconds in a week
549    */
550   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
551 
552   /**
553    * Seconds in a day, hour and minute
554    */
555   public static final int DAY_IN_SECONDS = 24 * 60 * 60;
556   public static final int HOUR_IN_SECONDS = 60 * 60;
557   public static final int MINUTE_IN_SECONDS = 60;
558 
559   //TODO: although the following are referenced widely to format strings for
560   //      the shell. They really aren't a part of the public API. It would be
561   //      nice if we could put them somewhere where they did not need to be
562   //      public. They could have package visibility
563   public static final String NAME = "NAME";
564   public static final String VERSIONS = "VERSIONS";
565   public static final String IN_MEMORY = "IN_MEMORY";
566   public static final String METADATA = "METADATA";
567   public static final String CONFIGURATION = "CONFIGURATION";
568 
569   /**
570    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
571    * run out of array items.  Retries beyond this use the last number in the array.  So, for
572    * example, if hbase.client.pause is 1 second, and maximum retries count
573    * hbase.client.retries.number is 10, we will retry at the following intervals:
574    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
575    * With 100ms, a back-off of 200 means 20s
576    */
577   public static final int RETRY_BACKOFF[] = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
578 
579   public static final String REGION_IMPL = "hbase.hregion.impl";
580 
581   /** modifyTable op for replacing the table descriptor */
582   @InterfaceAudience.Private
583   public static enum Modify {
584     CLOSE_REGION,
585     TABLE_COMPACT,
586     TABLE_FLUSH,
587     TABLE_MAJOR_COMPACT,
588     TABLE_SET_HTD,
589     TABLE_SPLIT
590   }
591 
592   /**
593    * Scope tag for locally scoped data.
594    * This data will not be replicated.
595    */
596   public static final int REPLICATION_SCOPE_LOCAL = 0;
597 
598   /**
599    * Scope tag for globally scoped data.
600    * This data will be replicated to all peers.
601    */
602   public static final int REPLICATION_SCOPE_GLOBAL = 1;
603 
604   /**
605    * Default cluster ID, cannot be used to identify a cluster so a key with
606    * this value means it wasn't meant for replication.
607    */
608   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
609 
610   /**
611    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
612    * Controlled by the client.
613    */
614   public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
615       "hbase.client.scanner.max.result.size";
616 
617   /**
618    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
619    * Controlled by the server.
620    */
621   public static final String HBASE_SERVER_SCANNER_MAX_RESULT_SIZE_KEY =
622       "hbase.server.scanner.max.result.size";
623 
624   /**
625    * Maximum number of bytes returned when calling a scanner's next method.
626    * Note that when a single row is larger than this limit the row is still
627    * returned completely.
628    *
629    * The default value is 2MB.
630    */
631   public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
632 
633   /**
634    * Maximum number of bytes returned when calling a scanner's next method.
635    * Note that when a single row is larger than this limit the row is still
636    * returned completely.
637    * Safety setting to protect the region server.
638    *
639    * The default value is 100MB. (a client would rarely request larger chunks on purpose)
640    */
641   public static final long DEFAULT_HBASE_SERVER_SCANNER_MAX_RESULT_SIZE = 100 * 1024 * 1024;
642 
643   /**
644    * Parameter name for client pause value, used mostly as value to wait
645    * before running a retry of a failed get, region lookup, etc.
646    */
647   public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
648 
649   /**
650    * Default value of {@link #HBASE_CLIENT_PAUSE}.
651    */
652   public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
653 
654   /**
655    * The maximum number of concurrent connections the client will maintain.
656    */
657   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
658 
659   /**
660    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
661    */
662   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
663 
664   /**
665    * The maximum number of concurrent connections the client will maintain to a single
666    * RegionServer.
667    */
668   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
669 
670   /**
671    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
672    */
673   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
674 
675   /**
676    * The maximum number of concurrent connections the client will maintain to a single
677    * Region.
678    */
679   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
680 
681   /**
682    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
683    */
684   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
685 
686   /**
687    * Parameter name for server pause value, used mostly as value to wait before
688    * running a retry of a failed operation.
689    */
690   public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
691 
692   /**
693    * Default value of {@link #HBASE_SERVER_PAUSE}.
694    */
695   public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
696 
697   /**
698    * Parameter name for maximum retries, used as maximum for all retryable
699    * operations such as fetching of the root region from root region server,
700    * getting a cell's value, starting a row update, etc.
701    */
702   public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
703 
704   /**
705    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
706    */
707   public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
708 
709   /**
710    * Parameter name to set the default scanner caching for all clients.
711    */
712   public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
713 
714   /**
715    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
716    */
717   public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = Integer.MAX_VALUE;
718 
719   /**
720    * Parameter name for number of versions, kept by meta table.
721    */
722   public static String HBASE_META_VERSIONS = "hbase.meta.versions";
723 
724   /**
725    * Default value of {@link #HBASE_META_VERSIONS}.
726    */
727   public static int DEFAULT_HBASE_META_VERSIONS = 10;
728 
729   /**
730    * Parameter name for number of versions, kept by meta table.
731    */
732   public static String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
733 
734   /**
735    * Default value of {@link #HBASE_META_BLOCK_SIZE}.
736    */
737   public static int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
738 
739   /**
740    * Parameter name for number of rows that will be fetched when calling next on
741    * a scanner if it is not served from memory. Higher caching values will
742    * enable faster scanners but will eat up more memory and some calls of next
743    * may take longer and longer times when the cache is empty.
744    */
745   public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
746 
747   /**
748    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
749    */
750   public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
751 
752   /**
753    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
754    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
755    * for all intents and purposes, are the same except for their instance ids, then they will not be
756    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
757    * even if the instance ids are the same, it could result in non-shared
758    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
759    * differ.
760    */
761   public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
762 
763   /**
764    * The client scanner timeout period in milliseconds.
765    */
766   public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
767 
768   /**
769    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
770    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
771    */
772   @Deprecated
773   public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
774       "hbase.regionserver.lease.period";
775 
776   /**
777    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
778    */
779   public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
780 
781   /**
782    * timeout for each RPC
783    */
784   public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
785 
786   /**
787    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
788    */
789   public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
790 
791   /**
792    * timeout for short operation RPC
793    */
794   public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY = "hbase.rpc.shortoperation.timeout";
795 
796   /**
797    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
798    */
799   public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
800 
801   /**
802    * Value indicating the server name was saved with no sequence number.
803    */
804   public static final long NO_SEQNUM = -1;
805 
806 
807   /*
808    * cluster replication constants.
809    */
810   public static final String
811       REPLICATION_ENABLE_KEY = "hbase.replication";
812   public static final boolean
813       REPLICATION_ENABLE_DEFAULT = true;
814   public static final String
815       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
816   public static final String
817       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
818   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
819     "org.apache.hadoop.hbase.replication.regionserver.Replication";
820 
821   /** HBCK special code name used as server name when manipulating ZK nodes */
822   public static final String HBCK_CODE_NAME = "HBCKServerName";
823 
824   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
825     "hbase.regionserver.hostname.seen.by.master";
826 
827   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
828       "hbase.master.logcleaner.plugins";
829 
830   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
831     "hbase.regionserver.region.split.policy";
832 
833   /** Whether nonces are enabled; default is true. */
834   public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
835 
836   /**
837    * Configuration key for the size of the block cache
838    */
839   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
840     "hfile.block.cache.size";
841 
842   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
843 
844   /*
845     * Minimum percentage of free heap necessary for a successful cluster startup.
846     */
847   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
848 
849   public static final Pattern CP_HTD_ATTR_KEY_PATTERN =
850       Pattern.compile("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
851 
852   /**
853    * Pattern that matches a coprocessor specification. Form is:
854    * <code>
855    *&lt;coprocessor jar file location> '|' &lt<class name> ['|' &lt;priority> ['|' &lt;arguments>]]
856    * </code>
857    * ...where arguments are <code>&lt;KEY> '=' &lt;VALUE> [,...]</code>
858    * <p>For example: <code>hdfs:///foo.jar|com.foo.FooRegionObserver|1001|arg1=1,arg2=2</code>
859    */
860   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
861       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
862 
863   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
864   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
865   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
866       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
867       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
868 
869   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
870   public static final int SOCKET_RETRY_WAIT_MS = 200;
871 
872   /** Host name of the local machine */
873   public static final String LOCALHOST = "localhost";
874 
875   /**
876    * If this parameter is set to true, then hbase will read
877    * data and then verify checksums. Checksum verification
878    * inside hdfs will be switched off.  However, if the hbase-checksum
879    * verification fails, then it will switch back to using
880    * hdfs checksums for verifiying data that is being read from storage.
881    *
882    * If this parameter is set to false, then hbase will not
883    * verify any checksums, instead it will depend on checksum verification
884    * being done in the hdfs client.
885    */
886   public static final String HBASE_CHECKSUM_VERIFICATION =
887       "hbase.regionserver.checksum.verify";
888 
889   public static final String LOCALHOST_IP = "127.0.0.1";
890 
891   /** Conf key that enables unflushed WAL edits directly being replayed to region servers */
892   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
893   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = false;
894 
895   public static final String DISALLOW_WRITES_IN_RECOVERING =
896       "hbase.regionserver.disallow.writes.when.recovering";
897   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
898 
899   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
900   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
901 
902   /*
903    * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
904    * -1  => Disable aborting
905    * 0   => Abort if even a single handler has died
906    * 0.x => Abort only when this percent of handlers have died
907    * 1   => Abort only all of the handers have died
908    */
909   public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
910 		  "hbase.regionserver.handler.abort.on.error.percent";
911   public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
912 
913   //High priority handlers to deal with admin requests and system table operation requests
914   public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
915       "hbase.regionserver.metahandler.count";
916   public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 20;
917 
918   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
919       "hbase.regionserver.replication.handler.count";
920   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
921 
922   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
923   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
924 
925   /** Conf key that specifies timeout value to wait for a region ready */
926   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
927       "hbase.master.log.replay.wait.region.timeout";
928 
929   /** Conf key for enabling meta replication */
930   public static final String USE_META_REPLICAS = "hbase.meta.replicas.use";
931   public static final boolean DEFAULT_USE_META_REPLICAS = false;
932   public static final String META_REPLICAS_NUM = "hbase.meta.replica.count";
933   public static final int DEFAULT_META_REPLICA_NUM = 1;
934 
935   /**
936    * The name of the configuration parameter that specifies
937    * the number of bytes in a newly created checksum chunk.
938    */
939   public static final String BYTES_PER_CHECKSUM =
940       "hbase.hstore.bytes.per.checksum";
941 
942   /**
943    * The name of the configuration parameter that specifies
944    * the name of an algorithm that is used to compute checksums
945    * for newly created blocks.
946    */
947   public static final String CHECKSUM_TYPE_NAME =
948       "hbase.hstore.checksum.algorithm";
949 
950   /** Enable file permission modification from standard hbase */
951   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
952   /** File permission umask to use when creating hbase data files */
953   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
954 
955   /** Configuration name of WAL Compression */
956   public static final String ENABLE_WAL_COMPRESSION =
957     "hbase.regionserver.wal.enablecompression";
958 
959   /** Configuration name of WAL storage policy
960    * Valid values are:
961    *  NONE: no preference in destination of block replicas
962    *  ONE_SSD: place only one block replica in SSD and the remaining in default storage
963    *  and ALL_SSD: place all block replicas on SSD
964    *
965    * See http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/ArchivalStorage.html*/
966   public static final String WAL_STORAGE_POLICY = "hbase.wal.storage.policy";
967   public static final String DEFAULT_WAL_STORAGE_POLICY = "NONE";
968 
969   /** Region in Transition metrics threshold time */
970   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
971 
972   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
973 
974   /**
975    * The byte array represents for NO_NEXT_INDEXED_KEY;
976    * The actual value is irrelevant because this is always compared by reference.
977    */
978   public static final Cell NO_NEXT_INDEXED_KEY = new KeyValue();
979   /** delimiter used between portions of a region name */
980   public static final int DELIMITER = ',';
981   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
982       "hbase.config.read.zookeeper.config";
983   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
984       false;
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 < 1.0) OR, it is the capacity in megabytes of the cache.
1145    */
1146   public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1147 
1148   /**
1149    * HConstants for fast fail on the client side follow
1150    */
1151   /**
1152    * Config for enabling/disabling the fast fail mode.
1153    */
1154   public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1155       "hbase.client.fast.fail.mode.enabled";
1156 
1157   public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT =
1158       false;
1159 
1160   public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1161       "hbase.client.fastfail.threshold";
1162 
1163   public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT =
1164       60000;
1165 
1166   public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1167       "hbase.client.fast.fail.cleanup.duration";
1168 
1169   public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT =
1170       600000;
1171 
1172   public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1173       "hbase.client.fast.fail.interceptor.impl";
1174 
1175   /** Config key for if the server should send backpressure and if the client should listen to
1176    * that backpressure from the server */
1177   public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1178   public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1179 
1180   public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1181       "hbase.heap.occupancy.low_water_mark";
1182   public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1183   public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1184       "hbase.heap.occupancy.high_water_mark";
1185   public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1186 
1187   /**
1188    * The max number of threads used for splitting storefiles in parallel during
1189    * the region split process.
1190    */
1191   public static final String REGION_SPLIT_THREADS_MAX =
1192     "hbase.regionserver.region.split.threads.max";
1193 
1194 
1195   /**
1196    * Configuration keys for programmatic JAAS configuration for secured ZK interaction
1197    */
1198   public static final String ZK_CLIENT_KEYTAB_FILE = "hbase.zookeeper.client.keytab.file";
1199   public static final String ZK_CLIENT_KERBEROS_PRINCIPAL =
1200       "hbase.zookeeper.client.kerberos.principal";
1201   public static final String ZK_SERVER_KEYTAB_FILE = "hbase.zookeeper.server.keytab.file";
1202   public static final String ZK_SERVER_KERBEROS_PRINCIPAL =
1203       "hbase.zookeeper.server.kerberos.principal";  
1204 
1205   /** Config key for hbase temporary directory in hdfs */
1206   public static final String TEMPORARY_FS_DIRECTORY_KEY = "hbase.fs.tmp.dir";
1207   public static final String DEFAULT_TEMPORARY_HDFS_DIRECTORY = "/user/"
1208       + System.getProperty("user.name") + "/hbase-staging";
1209 
1210   private HConstants() {
1211     // Can't be instantiated with this ctor.
1212   }
1213 }