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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   /** Cluster is standalone or pseudo-distributed */
131   public static final boolean CLUSTER_IS_LOCAL = false;
132 
133   /** Cluster is fully-distributed */
134   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
135 
136   /** Default value for cluster distributed mode */
137   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
138 
139   /** default host address */
140   public static final String DEFAULT_HOST = "0.0.0.0";
141 
142   /** Parameter name for port master listens on. */
143   public static final String MASTER_PORT = "hbase.master.port";
144 
145   /** default port that the master listens on */
146   public static final int DEFAULT_MASTER_PORT = 16000;
147 
148   /** default port for master web api */
149   public static final int DEFAULT_MASTER_INFOPORT = 16010;
150 
151   /** Configuration key for master web API port */
152   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
153 
154   /** Parameter name for the master type being backup (waits for primary to go inactive). */
155   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
156 
157   /** by default every master is a possible primary master unless the conf explicitly overrides it */
158   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
159 
160   /** Name of ZooKeeper quorum configuration parameter. */
161   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
162 
163   /** Name of ZooKeeper config file in conf/ directory. */
164   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
165 
166   /** Common prefix of ZooKeeper configuration properties */
167   public static final String ZK_CFG_PROPERTY_PREFIX =
168       "hbase.zookeeper.property.";
169 
170   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
171       ZK_CFG_PROPERTY_PREFIX.length();
172 
173   /**
174    * The ZK client port key in the ZK properties map. The name reflects the
175    * fact that this is not an HBase configuration key.
176    */
177   public static final String CLIENT_PORT_STR = "clientPort";
178 
179   /** Parameter name for the client port that the zookeeper listens on */
180   public static final String ZOOKEEPER_CLIENT_PORT =
181       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
182 
183   /** Default client port that the zookeeper listens on */
184   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
185 
186   /** Parameter name for the wait time for the recoverable zookeeper */
187   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";
188 
189   /** Default wait time for the recoverable zookeeper */
190   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
191 
192   /** Parameter name for the root dir in ZK for this cluster */
193   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
194 
195   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
196 
197   /**
198    * Parameter name for the limit on concurrent client-side zookeeper
199    * connections
200    */
201   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
202       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
203 
204   /** Parameter name for the ZK data directory */
205   public static final String ZOOKEEPER_DATA_DIR =
206       ZK_CFG_PROPERTY_PREFIX + "dataDir";
207 
208   /** Parameter name for the ZK tick time */
209   public static final String ZOOKEEPER_TICK_TIME =
210       ZK_CFG_PROPERTY_PREFIX + "tickTime";
211 
212   /** Default limit on concurrent client-side zookeeper connections */
213   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
214 
215   /** Configuration key for ZooKeeper session timeout */
216   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
217 
218   /** Default value for ZooKeeper session timeout */
219   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
220 
221   /** Configuration key for whether to use ZK.multi */
222   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
223 
224   /** Parameter name for port region server listens on. */
225   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
226 
227   /** Default port region server listens on. */
228   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
229 
230   /** default port for region server web api */
231   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
232 
233   /** A configuration key for regionserver info port */
234   public static final String REGIONSERVER_INFO_PORT =
235     "hbase.regionserver.info.port";
236 
237   /** A flag that enables automatic selection of regionserver info port */
238   public static final String REGIONSERVER_INFO_PORT_AUTO =
239       REGIONSERVER_INFO_PORT + ".auto";
240 
241   /** Parameter name for what region server implementation to use. */
242   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
243 
244   /** Parameter name for what master implementation to use. */
245   public static final String MASTER_IMPL= "hbase.master.impl";
246 
247   /** Parameter name for what hbase client implementation to use. */
248   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
249 
250   /** Parameter name for how often threads should wake up */
251   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
252 
253   /** Default value for thread wake frequency */
254   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
255 
256   /** Parameter name for how often we should try to write a version file, before failing */
257   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
258 
259   /** Parameter name for how often we should try to write a version file, before failing */
260   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
261 
262   /** Parameter name for how often a region should should perform a major compaction */
263   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
264 
265   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
266   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
267   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
268 
269   /** Parameter name for HBase instance root directory */
270   public static final String HBASE_DIR = "hbase.rootdir";
271 
272   /** Parameter name for HBase client IPC pool type */
273   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
274 
275   /** Parameter name for HBase client IPC pool size */
276   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
277 
278   /** Parameter name for HBase client operation timeout. */
279   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
280 
281   /** Parameter name for HBase client operation timeout. */
282   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
283     "hbase.client.meta.operation.timeout";
284 
285   /** Default HBase client operation timeout, which is tantamount to a blocking call */
286   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = 1200000;
287 
288   /** Used to construct the name of the log directory for a region server */
289   public static final String HREGION_LOGDIR_NAME = "WALs";
290 
291   /** Used to construct the name of the splitlog directory for a region server */
292   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
293 
294   /** Like the previous, but for old logs that are about to be deleted */
295   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
296 
297   public static final String CORRUPT_DIR_NAME = "corrupt";
298 
299   /** Used by HBCK to sideline backup data */
300   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
301 
302   /** Any artifacts left from migration can be moved here */
303   public static final String MIGRATION_NAME = ".migration";
304 
305   /**
306    * The directory from which co-processor/custom filter jars can be loaded
307    * dynamically by the region servers. This value can be overridden by the
308    * hbase.dynamic.jars.dir config.
309    */
310   public static final String LIB_DIR = "lib";
311 
312   /** Used to construct the name of the compaction directory during compaction */
313   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
314 
315   /** Conf key for the max file size after which we split the region */
316   public static final String HREGION_MAX_FILESIZE =
317       "hbase.hregion.max.filesize";
318 
319   /** Default maximum file size */
320   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
321 
322   /**
323    * Max size of single row for Get's or Scan's without in-row scanning flag set.
324    */
325   public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
326 
327   /**
328    * Default max row size (1 Gb).
329    */
330   public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
331 
332   /**
333    * The max number of threads used for opening and closing stores or store
334    * files in parallel
335    */
336   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
337     "hbase.hstore.open.and.close.threads.max";
338 
339   /**
340    * The default number for the max number of threads used for opening and
341    * closing stores or store files in parallel
342    */
343   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
344 
345   /**
346    * Block updates if memstore has hbase.hregion.memstore.block.multiplier
347    * times hbase.hregion.memstore.flush.size bytes.  Useful preventing
348    * runaway memstore during spikes in update traffic.
349    */
350   public static final String HREGION_MEMSTORE_BLOCK_MULTIPLIER =
351           "hbase.hregion.memstore.block.multiplier";
352 
353   /**
354    * Default value for hbase.hregion.memstore.block.multiplier
355    */
356   public static final int DEFAULT_HREGION_MEMSTORE_BLOCK_MULTIPLIER = 4;
357 
358   /** Conf key for the memstore size at which we flush the memstore */
359   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
360       "hbase.hregion.memstore.flush.size";
361 
362   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
363       "hbase.hregion.edits.replay.skip.errors";
364 
365   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
366       false;
367 
368   /** Maximum value length, enforced on KeyValue construction */
369   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
370 
371   /** name of the file for unique cluster ID */
372   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
373 
374   /** Default value for cluster ID */
375   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
376 
377   /** Parameter name for # days to keep MVCC values during a major compaction */
378   public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
379   /** At least to keep MVCC values in hfiles for 5 days */
380   public static final int MIN_KEEP_SEQID_PERIOD = 5;
381 
382   // Always store the location of the root table's HRegion.
383   // This HRegion is never split.
384 
385   // region name = table + startkey + regionid. This is the row key.
386   // each row in the root and meta tables describes exactly 1 region
387   // Do we ever need to know all the information that we are storing?
388 
389   // Note that the name of the root table starts with "-" and the name of the
390   // meta table starts with "." Why? it's a trick. It turns out that when we
391   // store region names in memory, we use a SortedMap. Since "-" sorts before
392   // "." (and since no other table name can start with either of these
393   // characters, the root region will always be the first entry in such a Map,
394   // followed by all the meta regions (which will be ordered by their starting
395   // row key as well), followed by all user tables. So when the Master is
396   // choosing regions to assign, it will always choose the root region first,
397   // followed by the meta regions, followed by user regions. Since the root
398   // and meta regions always need to be on-line, this ensures that they will
399   // be the first to be reassigned if the server(s) they are being served by
400   // should go down.
401 
402 
403   /**
404    * The hbase:meta table's name.
405    * @deprecated For upgrades of 0.94 to 0.96
406    */
407   @Deprecated  // for compat from 0.94 -> 0.96.
408   public static final byte[] META_TABLE_NAME = TableName.META_TABLE_NAME.getName();
409 
410   public static final String BASE_NAMESPACE_DIR = "data";
411 
412   /** delimiter used between portions of a region name */
413   public static final int META_ROW_DELIMITER = ',';
414 
415   /** The catalog family as a string*/
416   public static final String CATALOG_FAMILY_STR = "info";
417 
418   /** The catalog family */
419   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
420 
421   /** The RegionInfo qualifier as a string */
422   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
423 
424   /** The regioninfo column qualifier */
425   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
426 
427   /** The server column qualifier */
428   public static final String SERVER_QUALIFIER_STR = "server";
429   /** The server column qualifier */
430   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes(SERVER_QUALIFIER_STR);
431 
432   /** The startcode column qualifier */
433   public static final String STARTCODE_QUALIFIER_STR = "serverstartcode";
434   /** The startcode column qualifier */
435   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes(STARTCODE_QUALIFIER_STR);
436 
437   /** The open seqnum column qualifier */
438   public static final String SEQNUM_QUALIFIER_STR = "seqnumDuringOpen";
439   /** The open seqnum column qualifier */
440   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes(SEQNUM_QUALIFIER_STR);
441 
442   /** The state column qualifier */
443   public static final String STATE_QUALIFIER_STR = "state";
444 
445   public static final byte [] STATE_QUALIFIER = Bytes.toBytes(STATE_QUALIFIER_STR);
446 
447   /**
448    * The serverName column qualifier. Its the server where the region is
449    * transitioning on, while column server is the server where the region is
450    * opened on. They are the same when the region is in state OPEN.
451    */
452   public static final String SERVERNAME_QUALIFIER_STR = "sn";
453 
454   public static final byte [] SERVERNAME_QUALIFIER = Bytes.toBytes(SERVERNAME_QUALIFIER_STR);
455 
456   /** The lower-half split region column qualifier */
457   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
458 
459   /** The upper-half split region column qualifier */
460   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
461 
462   /** The lower-half merge region column qualifier */
463   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
464 
465   /** The upper-half merge region column qualifier */
466   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
467 
468   /**
469    * The meta table version column qualifier.
470    * We keep current version of the meta table in this column in <code>-ROOT-</code>
471    * table: i.e. in the 'info:v' column.
472    */
473   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
474 
475   /**
476    * The current version of the meta table.
477    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
478    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
479    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
480    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
481    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
482    * byte[] serialization from Writables to Protobuf.
483    * See HRegionInfo.VERSION
484    */
485   public static final short META_VERSION = 1;
486 
487   // Other constants
488 
489   /**
490    * An empty instance.
491    */
492   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
493 
494   /**
495    * Used by scanners, etc when they want to start at the beginning of a region
496    */
497   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
498 
499   /**
500    * Last row in a table.
501    */
502   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
503 
504   /**
505     * Used by scanners and others when they're trying to detect the end of a
506     * table
507     */
508   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
509 
510   /**
511    * Max length a row can have because of the limitation in TFile.
512    */
513   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
514 
515   /**
516    * Timestamp to use when we want to refer to the latest cell.
517    * This is the timestamp sent by clients when no timestamp is specified on
518    * commit.
519    */
520   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
521 
522   /**
523    * Timestamp to use when we want to refer to the oldest cell.
524    */
525   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
526 
527   /**
528    * LATEST_TIMESTAMP in bytes form
529    */
530   public static final byte [] LATEST_TIMESTAMP_BYTES = {
531     // big-endian
532     (byte) (LATEST_TIMESTAMP >>> 56),
533     (byte) (LATEST_TIMESTAMP >>> 48),
534     (byte) (LATEST_TIMESTAMP >>> 40),
535     (byte) (LATEST_TIMESTAMP >>> 32),
536     (byte) (LATEST_TIMESTAMP >>> 24),
537     (byte) (LATEST_TIMESTAMP >>> 16),
538     (byte) (LATEST_TIMESTAMP >>> 8),
539     (byte) LATEST_TIMESTAMP,
540   };
541 
542   /**
543    * Define for 'return-all-versions'.
544    */
545   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
546 
547   /**
548    * Unlimited time-to-live.
549    */
550 //  public static final int FOREVER = -1;
551   public static final int FOREVER = Integer.MAX_VALUE;
552 
553   /**
554    * Seconds in a week
555    */
556   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
557 
558   /**
559    * Seconds in a day, hour and minute
560    */
561   public static final int DAY_IN_SECONDS = 24 * 60 * 60;
562   public static final int HOUR_IN_SECONDS = 60 * 60;
563   public static final int MINUTE_IN_SECONDS = 60;
564 
565   //TODO: although the following are referenced widely to format strings for
566   //      the shell. They really aren't a part of the public API. It would be
567   //      nice if we could put them somewhere where they did not need to be
568   //      public. They could have package visibility
569   public static final String NAME = "NAME";
570   public static final String VERSIONS = "VERSIONS";
571   public static final String IN_MEMORY = "IN_MEMORY";
572   public static final String METADATA = "METADATA";
573   public static final String CONFIGURATION = "CONFIGURATION";
574 
575   /**
576    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
577    * run out of array items.  Retries beyond this use the last number in the array.  So, for
578    * example, if hbase.client.pause is 1 second, and maximum retries count
579    * hbase.client.retries.number is 10, we will retry at the following intervals:
580    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
581    * With 100ms, a back-off of 200 means 20s
582    */
583   public static final int [] RETRY_BACKOFF = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
584 
585   public static final String REGION_IMPL = "hbase.hregion.impl";
586 
587   /** modifyTable op for replacing the table descriptor */
588   @InterfaceAudience.Private
589   public static enum Modify {
590     CLOSE_REGION,
591     TABLE_COMPACT,
592     TABLE_FLUSH,
593     TABLE_MAJOR_COMPACT,
594     TABLE_SET_HTD,
595     TABLE_SPLIT
596   }
597 
598   /**
599    * Scope tag for locally scoped data.
600    * This data will not be replicated.
601    */
602   public static final int REPLICATION_SCOPE_LOCAL = 0;
603 
604   /**
605    * Scope tag for globally scoped data.
606    * This data will be replicated to all peers.
607    */
608   public static final int REPLICATION_SCOPE_GLOBAL = 1;
609 
610   /**
611    * Default cluster ID, cannot be used to identify a cluster so a key with
612    * this value means it wasn't meant for replication.
613    */
614   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
615 
616   /**
617    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
618    * Controlled by the client.
619    */
620   public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
621       "hbase.client.scanner.max.result.size";
622 
623   /**
624    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
625    * Controlled by the server.
626    */
627   public static final String HBASE_SERVER_SCANNER_MAX_RESULT_SIZE_KEY =
628       "hbase.server.scanner.max.result.size";
629 
630   /**
631    * Maximum number of bytes returned when calling a scanner's next method.
632    * Note that when a single row is larger than this limit the row is still
633    * returned completely.
634    *
635    * The default value is 2MB.
636    */
637   public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
638 
639   /**
640    * Maximum number of bytes returned when calling a scanner's next method.
641    * Note that when a single row is larger than this limit the row is still
642    * returned completely.
643    * Safety setting to protect the region server.
644    *
645    * The default value is 100MB. (a client would rarely request larger chunks on purpose)
646    */
647   public static final long DEFAULT_HBASE_SERVER_SCANNER_MAX_RESULT_SIZE = 100 * 1024 * 1024;
648 
649   /**
650    * Parameter name for client pause value, used mostly as value to wait
651    * before running a retry of a failed get, region lookup, etc.
652    */
653   public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
654 
655   /**
656    * Default value of {@link #HBASE_CLIENT_PAUSE}.
657    */
658   public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
659 
660   /**
661    * The maximum number of concurrent connections the client will maintain.
662    */
663   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
664 
665   /**
666    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
667    */
668   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
669 
670   /**
671    * The maximum number of concurrent connections the client will maintain to a single
672    * RegionServer.
673    */
674   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
675 
676   /**
677    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
678    */
679   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
680 
681   /**
682    * The maximum number of concurrent connections the client will maintain to a single
683    * Region.
684    */
685   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
686 
687   /**
688    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
689    */
690   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
691 
692   /**
693    * Parameter name for server pause value, used mostly as value to wait before
694    * running a retry of a failed operation.
695    */
696   public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
697 
698   /**
699    * Default value of {@link #HBASE_SERVER_PAUSE}.
700    */
701   public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
702 
703   /**
704    * Parameter name for maximum retries, used as maximum for all retryable
705    * operations such as fetching of the root region from root region server,
706    * getting a cell's value, starting a row update, etc.
707    */
708   public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
709 
710   /**
711    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
712    */
713   public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
714 
715   /**
716    * Parameter name to set the default scanner caching for all clients.
717    */
718   public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
719 
720   /**
721    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
722    */
723   public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = Integer.MAX_VALUE;
724 
725   /**
726    * Parameter name for number of versions, kept by meta table.
727    */
728   public static String HBASE_META_VERSIONS = "hbase.meta.versions";
729 
730   /**
731    * Default value of {@link #HBASE_META_VERSIONS}.
732    */
733   public static int DEFAULT_HBASE_META_VERSIONS = 10;
734 
735   /**
736    * Parameter name for number of versions, kept by meta table.
737    */
738   public static String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
739 
740   /**
741    * Default value of {@link #HBASE_META_BLOCK_SIZE}.
742    */
743   public static int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
744 
745   /**
746    * Parameter name for number of rows that will be fetched when calling next on
747    * a scanner if it is not served from memory. Higher caching values will
748    * enable faster scanners but will eat up more memory and some calls of next
749    * may take longer and longer times when the cache is empty.
750    */
751   public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
752 
753   /**
754    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
755    */
756   public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
757 
758   /**
759    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
760    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
761    * for all intents and purposes, are the same except for their instance ids, then they will not be
762    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
763    * even if the instance ids are the same, it could result in non-shared
764    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
765    * differ.
766    */
767   public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
768 
769   /**
770    * The client scanner timeout period in milliseconds.
771    */
772   public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
773 
774   /**
775    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
776    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
777    */
778   @Deprecated
779   public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
780       "hbase.regionserver.lease.period";
781 
782   /**
783    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
784    */
785   public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
786 
787   /**
788    * timeout for each RPC
789    */
790   public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
791 
792   /**
793    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
794    */
795   public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
796 
797   /**
798    * timeout for short operation RPC
799    */
800   public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY =
801       "hbase.rpc.shortoperation.timeout";
802 
803   /**
804    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
805    */
806   public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
807 
808   /**
809    * Value indicating the server name was saved with no sequence number.
810    */
811   public static final long NO_SEQNUM = -1;
812 
813 
814   /*
815    * cluster replication constants.
816    */
817   public static final String
818       REPLICATION_ENABLE_KEY = "hbase.replication";
819   public static final boolean
820       REPLICATION_ENABLE_DEFAULT = true;
821   public static final String
822       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
823   public static final String
824       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
825   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
826     "org.apache.hadoop.hbase.replication.regionserver.Replication";
827 
828   /** HBCK special code name used as server name when manipulating ZK nodes */
829   public static final String HBCK_CODE_NAME = "HBCKServerName";
830 
831   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
832     "hbase.regionserver.hostname.seen.by.master";
833 
834   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
835       "hbase.master.logcleaner.plugins";
836 
837   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
838     "hbase.regionserver.region.split.policy";
839 
840   /** Whether nonces are enabled; default is true. */
841   public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
842 
843   /**
844    * Configuration key for the size of the block cache
845    */
846   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
847     "hfile.block.cache.size";
848 
849   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
850 
851   /*
852     * Minimum percentage of free heap necessary for a successful cluster startup.
853     */
854   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
855 
856   public static final Pattern CP_HTD_ATTR_KEY_PATTERN =
857       Pattern.compile("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
858 
859   /**
860    * Pattern that matches a coprocessor specification. Form is:
861    * <code>
862    *&lt;coprocessor jar file location> '|' &lt<class name> ['|' &lt;priority> ['|' &lt;arguments>]]
863    * </code>
864    * ...where arguments are <code>&lt;KEY> '=' &lt;VALUE> [,...]</code>
865    * <p>For example: <code>hdfs:///foo.jar|com.foo.FooRegionObserver|1001|arg1=1,arg2=2</code>
866    */
867   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
868       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
869 
870   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
871   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
872   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
873       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
874       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
875 
876   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
877   public static final int SOCKET_RETRY_WAIT_MS = 200;
878 
879   /** Host name of the local machine */
880   public static final String LOCALHOST = "localhost";
881 
882   /**
883    * If this parameter is set to true, then hbase will read
884    * data and then verify checksums. Checksum verification
885    * inside hdfs will be switched off.  However, if the hbase-checksum
886    * verification fails, then it will switch back to using
887    * hdfs checksums for verifiying data that is being read from storage.
888    *
889    * If this parameter is set to false, then hbase will not
890    * verify any checksums, instead it will depend on checksum verification
891    * being done in the hdfs client.
892    */
893   public static final String HBASE_CHECKSUM_VERIFICATION =
894       "hbase.regionserver.checksum.verify";
895 
896   public static final String LOCALHOST_IP = "127.0.0.1";
897 
898   /** Conf key that enables unflushed WAL edits directly being replayed to region servers
899    */
900   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
901   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = false;
902   public static final String DISALLOW_WRITES_IN_RECOVERING =
903       "hbase.regionserver.disallow.writes.when.recovering";
904   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
905 
906   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
907   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
908 
909   /*
910    * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
911    * -1  => Disable aborting
912    * 0   => Abort if even a single handler has died
913    * 0.x => Abort only when this percent of handlers have died
914    * 1   => Abort only all of the handers have died
915    */
916   public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
917       "hbase.regionserver.handler.abort.on.error.percent";
918   public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
919 
920   //High priority handlers to deal with admin requests and system table operation requests
921   public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
922       "hbase.regionserver.metahandler.count";
923   public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 20;
924 
925   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
926       "hbase.regionserver.replication.handler.count";
927   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
928 
929   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
930   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
931 
932   /** Conf key that specifies timeout value to wait for a region ready */
933   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
934       "hbase.master.log.replay.wait.region.timeout";
935 
936   /** Conf key for enabling meta replication */
937   public static final String USE_META_REPLICAS = "hbase.meta.replicas.use";
938   public static final boolean DEFAULT_USE_META_REPLICAS = false;
939   public static final String META_REPLICAS_NUM = "hbase.meta.replica.count";
940   public static final int DEFAULT_META_REPLICA_NUM = 1;
941 
942   /**
943    * The name of the configuration parameter that specifies
944    * the number of bytes in a newly created checksum chunk.
945    */
946   public static final String BYTES_PER_CHECKSUM =
947       "hbase.hstore.bytes.per.checksum";
948 
949   /**
950    * The name of the configuration parameter that specifies
951    * the name of an algorithm that is used to compute checksums
952    * for newly created blocks.
953    */
954   public static final String CHECKSUM_TYPE_NAME =
955       "hbase.hstore.checksum.algorithm";
956 
957   /** Enable file permission modification from standard hbase */
958   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
959   /** File permission umask to use when creating hbase data files */
960   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
961 
962   /** Configuration name of WAL Compression */
963   public static final String ENABLE_WAL_COMPRESSION =
964     "hbase.regionserver.wal.enablecompression";
965 
966   /** Configuration name of WAL storage policy
967    * Valid values are:
968    *  NONE: no preference in destination of block replicas
969    *  ONE_SSD: place only one block replica in SSD and the remaining in default storage
970    *  and ALL_SSD: place all block replicas on SSD
971    *
972    * See http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/ArchivalStorage.html*/
973   public static final String WAL_STORAGE_POLICY = "hbase.wal.storage.policy";
974   public static final String DEFAULT_WAL_STORAGE_POLICY = "NONE";
975 
976   /** Region in Transition metrics threshold time */
977   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD =
978       "hbase.metrics.rit.stuck.warning.threshold";
979 
980   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
981 
982   /** delimiter used between portions of a region name */
983   public static final int DELIMITER = ',';
984   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
985       "hbase.config.read.zookeeper.config";
986   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
987       false;
988 
989   /**
990    * QOS attributes: these attributes are used to demarcate RPC call processing
991    * by different set of handlers. For example, HIGH_QOS tagged methods are
992    * handled by high priority handlers.
993    */
994   // normal_QOS < QOS_threshold < replication_QOS < replay_QOS < admin_QOS < high_QOS
995   public static final int NORMAL_QOS = 0;
996   public static final int QOS_THRESHOLD = 10;
997   public static final int HIGH_QOS = 200;
998   public static final int REPLICATION_QOS = 5;
999   public static final int REPLAY_QOS = 6;
1000   public static final int ADMIN_QOS = 100;
1001   public static final int SYSTEMTABLE_QOS = HIGH_QOS;
1002 
1003   /** Directory under /hbase where archived hfiles are stored */
1004   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
1005 
1006   /**
1007    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
1008    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
1009    * uni-directional.
1010    */
1011   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
1012 
1013   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
1014   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
1015 
1016   /** Temporary directory used for table creation and deletion */
1017   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
1018   /**
1019    * The period (in milliseconds) between computing region server point in time metrics
1020    */
1021   public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
1022   public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
1023   /** Directories that are not HBase table directories */
1024   public static final List<String> HBASE_NON_TABLE_DIRS =
1025     Collections.unmodifiableList(Arrays.asList(new String[] {
1026       HBCK_SIDELINEDIR_NAME, HBASE_TEMP_DIRECTORY, MIGRATION_NAME
1027     }));
1028 
1029   /** Directories that are not HBase user table directories */
1030   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
1031     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
1032       new String[] { TableName.META_TABLE_NAME.getNameAsString() },
1033       HBASE_NON_TABLE_DIRS.toArray())));
1034 
1035   /** Health script related settings. */
1036   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
1037   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
1038   public static final String HEALTH_CHORE_WAKE_FREQ =
1039       "hbase.node.health.script.frequency";
1040   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
1041   /**
1042    * The maximum number of health check failures a server can encounter consecutively.
1043    */
1044   public static final String HEALTH_FAILURE_THRESHOLD =
1045       "hbase.node.health.failure.threshold";
1046   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
1047 
1048 
1049   /**
1050    * Setting to activate, or not, the publication of the status by the master. Default
1051    *  notification is by a multicast message.
1052    */
1053   public static final String STATUS_PUBLISHED = "hbase.status.published";
1054   public static final boolean STATUS_PUBLISHED_DEFAULT = false;
1055 
1056   /**
1057    * IP to use for the multicast status messages between the master and the clients.
1058    * The default address is chosen as one among others within the ones suitable for multicast
1059    * messages.
1060    */
1061   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
1062   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
1063 
1064   /**
1065    * The address to use for binding the local socket for receiving multicast. Defaults to
1066    * 0.0.0.0.
1067    * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
1068    */
1069   public static final String STATUS_MULTICAST_BIND_ADDRESS =
1070       "hbase.status.multicast.bind.address.ip";
1071   public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
1072 
1073   /**
1074    * The port to use for the multicast messages.
1075    */
1076   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
1077   public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
1078 
1079   public static final long NO_NONCE = 0;
1080 
1081   /** Default cipher for encryption */
1082   public static final String CIPHER_AES = "AES";
1083 
1084   /** Configuration key for the crypto algorithm provider, a class name */
1085   public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
1086 
1087   /** Configuration key for the crypto key provider, a class name */
1088   public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
1089 
1090   /** Configuration key for the crypto key provider parameters */
1091   public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
1092       "hbase.crypto.keyprovider.parameters";
1093 
1094   /** Configuration key for the name of the master key for the cluster, a string */
1095   public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
1096 
1097   /** Configuration key for the name of the alternate master key for the cluster, a string */
1098   public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
1099     "hbase.crypto.master.alternate.key.name";
1100 
1101   /** Configuration key for the algorithm to use when encrypting the WAL, a string */
1102   public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
1103 
1104   /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
1105   public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
1106 
1107   /** Configuration key for the algorithm used for creating jks key, a string */
1108   public static final String CRYPTO_KEY_ALGORITHM_CONF_KEY = "hbase.crypto.key.algorithm";
1109 
1110   /** Configuration key for the name of the alternate cipher algorithm for the cluster, a string */
1111   public static final String CRYPTO_ALTERNATE_KEY_ALGORITHM_CONF_KEY =
1112       "hbase.crypto.alternate.key.algorithm";
1113 
1114   /** Configuration key for enabling WAL encryption, a boolean */
1115   public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
1116 
1117   /** Configuration key for setting RPC codec class name */
1118   public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
1119 
1120   /** Configuration key for setting replication codec class name */
1121   public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
1122 
1123   /** Maximum number of threads used by the replication source for shipping edits to the sinks */
1124   public static final String REPLICATION_SOURCE_MAXTHREADS_KEY =
1125       "hbase.replication.source.maxthreads";
1126 
1127   public static final int REPLICATION_SOURCE_MAXTHREADS_DEFAULT = 10;
1128 
1129   /** Config for pluggable consensus provider */
1130   public static final String HBASE_COORDINATED_STATE_MANAGER_CLASS =
1131     "hbase.coordinated.state.manager.class";
1132 
1133   /** Configuration key for SplitLog manager timeout */
1134   public static final String HBASE_SPLITLOG_MANAGER_TIMEOUT = "hbase.splitlog.manager.timeout";
1135 
1136   /**
1137    * Configuration keys for Bucket cache
1138    */
1139   // TODO moving these bucket cache implementation specific configs to this level is violation of
1140   // encapsulation. But as these has to be referred from hbase-common and bucket cache
1141   // sits in hbase-server, there were no other go! Can we move the cache implementation to
1142   // hbase-common?
1143 
1144   /**
1145    * Current ioengine options in include: heap, offheap and file:PATH (where PATH is the path
1146    * to the file that will host the file-based cache.  See BucketCache#getIOEngineFromName() for
1147    * list of supported ioengine options.
1148    * <p>Set this option and a non-zero {@link #BUCKET_CACHE_SIZE_KEY} to enable bucket cache.
1149    */
1150   public static final String BUCKET_CACHE_IOENGINE_KEY = "hbase.bucketcache.ioengine";
1151 
1152   /**
1153    * When using bucket cache, this is a float that EITHER represents a percentage of total heap
1154    * memory size to give to the cache (if &lt; 1.0) OR, it is the capacity in
1155    * megabytes of the cache.
1156    */
1157   public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1158 
1159   /**
1160    * HConstants for fast fail on the client side follow
1161    */
1162   /**
1163    * Config for enabling/disabling the fast fail mode.
1164    */
1165   public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1166       "hbase.client.fast.fail.mode.enabled";
1167 
1168   public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT =
1169       false;
1170 
1171   public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1172       "hbase.client.fastfail.threshold";
1173 
1174   public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT =
1175       60000;
1176 
1177   public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1178       "hbase.client.fast.fail.cleanup.duration";
1179 
1180   public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT =
1181       600000;
1182 
1183   public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1184       "hbase.client.fast.fail.interceptor.impl";
1185 
1186   /** Config key for if the server should send backpressure and if the client should listen to
1187    * that backpressure from the server */
1188   public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1189   public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1190 
1191   public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1192       "hbase.heap.occupancy.low_water_mark";
1193   public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1194   public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1195       "hbase.heap.occupancy.high_water_mark";
1196   public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1197 
1198   /**
1199    * The max number of threads used for splitting storefiles in parallel during
1200    * the region split process.
1201    */
1202   public static final String REGION_SPLIT_THREADS_MAX =
1203     "hbase.regionserver.region.split.threads.max";
1204 
1205   /** Canary config keys */
1206   public static final String HBASE_CANARY_WRITE_DATA_TTL_KEY = "hbase.canary.write.data.ttl";
1207 
1208   public static final String HBASE_CANARY_WRITE_PERSERVER_REGIONS_LOWERLIMIT_KEY =
1209       "hbase.canary.write.perserver.regions.lowerLimit";
1210 
1211   public static final String HBASE_CANARY_WRITE_PERSERVER_REGIONS_UPPERLIMIT_KEY =
1212       "hbase.canary.write.perserver.regions.upperLimit";
1213 
1214   public static final String HBASE_CANARY_WRITE_VALUE_SIZE_KEY = "hbase.canary.write.value.size";
1215 
1216   public static final String HBASE_CANARY_WRITE_TABLE_CHECK_PERIOD_KEY =
1217       "hbase.canary.write.table.check.period";
1218   
1219   /**
1220    * Configuration keys for programmatic JAAS configuration for secured ZK interaction
1221    */
1222   public static final String ZK_CLIENT_KEYTAB_FILE = "hbase.zookeeper.client.keytab.file";
1223   public static final String ZK_CLIENT_KERBEROS_PRINCIPAL =
1224       "hbase.zookeeper.client.kerberos.principal";
1225   public static final String ZK_SERVER_KEYTAB_FILE = "hbase.zookeeper.server.keytab.file";
1226   public static final String ZK_SERVER_KERBEROS_PRINCIPAL =
1227       "hbase.zookeeper.server.kerberos.principal";  
1228 
1229   /** Config key for hbase temporary directory in hdfs */
1230   public static final String TEMPORARY_FS_DIRECTORY_KEY = "hbase.fs.tmp.dir";
1231   public static final String DEFAULT_TEMPORARY_HDFS_DIRECTORY = "/user/"
1232       + System.getProperty("user.name") + "/hbase-staging";
1233 
1234   private HConstants() {
1235     // Can't be instantiated with this ctor.
1236   }
1237 }