001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase;
019
020import static org.apache.hadoop.hbase.io.hfile.BlockType.MAGIC_LENGTH;
021
022import java.nio.ByteBuffer;
023import java.nio.charset.Charset;
024import java.util.Arrays;
025import java.util.Collections;
026import java.util.List;
027import java.util.UUID;
028import java.util.regex.Pattern;
029import org.apache.commons.lang3.ArrayUtils;
030import org.apache.hadoop.hbase.util.Bytes;
031import org.apache.yetus.audience.InterfaceAudience;
032
033/**
034 * HConstants holds a bunch of HBase-related constants
035 */
036@InterfaceAudience.Public
037public final class HConstants {
038  // NOTICE!!!! Please do not add a constants here, unless they are referenced by a lot of classes.
039
040  //Bytes.UTF8_ENCODING should be updated if this changed
041  /** When we encode strings, we always specify UTF8 encoding */
042  public static final String UTF8_ENCODING = "UTF-8";
043
044  //Bytes.UTF8_CHARSET should be updated if this changed
045  /** When we encode strings, we always specify UTF8 encoding */
046  public static final Charset UTF8_CHARSET = Charset.forName(UTF8_ENCODING);
047  /**
048   * Default block size for an HFile.
049   */
050  public final static int DEFAULT_BLOCKSIZE = 64 * 1024;
051
052  /** Used as a magic return value while optimized index key feature enabled(HBASE-7845) */
053  public final static int INDEX_KEY_MAGIC = -2;
054  /*
055     * Name of directory that holds recovered edits written by the wal log
056     * splitting code, one per region
057     */
058  public static final String RECOVERED_EDITS_DIR = "recovered.edits";
059  /**
060   * The first four bytes of Hadoop RPC connections
061   */
062  public static final byte[] RPC_HEADER = new byte[] { 'H', 'B', 'a', 's' };
063  public static final byte RPC_CURRENT_VERSION = 0;
064
065  // HFileBlock constants. TODO!!!! THESE DEFINES BELONG IN HFILEBLOCK, NOT UP HERE.
066  // Needed down in hbase-common though by encoders but these encoders should not be dealing
067  // in the internals of hfileblocks. Fix encapsulation.
068
069  /** The size data structures with minor version is 0 */
070  public static final int HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM = MAGIC_LENGTH + 2 * Bytes.SIZEOF_INT
071      + Bytes.SIZEOF_LONG;
072  /** The size of a version 2 HFile block header, minor version 1.
073   * There is a 1 byte checksum type, followed by a 4 byte bytesPerChecksum
074   * followed by another 4 byte value to store sizeofDataOnDisk.
075   */
076  public static final int HFILEBLOCK_HEADER_SIZE = HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM +
077    Bytes.SIZEOF_BYTE + 2 * Bytes.SIZEOF_INT;
078  /** Just an array of bytes of the right size. */
079  public static final byte[] HFILEBLOCK_DUMMY_HEADER = new byte[HFILEBLOCK_HEADER_SIZE];
080
081  //End HFileBlockConstants.
082
083  /**
084   * Status codes used for return values of bulk operations.
085   */
086  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
087  public enum OperationStatusCode {
088    NOT_RUN,
089    SUCCESS,
090    BAD_FAMILY,
091    STORE_TOO_BUSY,
092    SANITY_CHECK_FAILURE,
093    FAILURE
094  }
095
096  /** long constant for zero */
097  public static final Long ZERO_L = Long.valueOf(0L);
098  public static final String NINES = "99999999999999";
099  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  /** Config for balancing the cluster by table */
128  public static final String HBASE_MASTER_LOADBALANCE_BYTABLE = "hbase.master.loadbalance.bytable";
129
130  /** Config for the max percent of regions in transition */
131  public static final String HBASE_MASTER_BALANCER_MAX_RIT_PERCENT =
132      "hbase.master.balancer.maxRitPercent";
133
134  /** Default value for the max percent of regions in transition */
135  public static final double DEFAULT_HBASE_MASTER_BALANCER_MAX_RIT_PERCENT = 1.0;
136
137  /** Config for the max balancing time */
138  public static final String HBASE_BALANCER_MAX_BALANCING = "hbase.balancer.max.balancing";
139
140  /** Config for the balancer period */
141  public static final String HBASE_BALANCER_PERIOD = "hbase.balancer.period";
142
143  /** Default value for the balancer period */
144  public static final int DEFAULT_HBASE_BALANCER_PERIOD = 300000;
145
146  /** The name of the ensemble table */
147  public static final TableName ENSEMBLE_TABLE_NAME = TableName.valueOf("hbase:ensemble");
148
149  /** Config for pluggable region normalizer */
150  public static final String HBASE_MASTER_NORMALIZER_CLASS =
151    "hbase.master.normalizer.class";
152
153  /** Cluster is standalone or pseudo-distributed */
154  public static final boolean CLUSTER_IS_LOCAL = false;
155
156  /** Default value for cluster distributed mode */
157  public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
158
159  /** default host address */
160  public static final String DEFAULT_HOST = "0.0.0.0";
161
162  /** Parameter name for port master listens on. */
163  public static final String MASTER_PORT = "hbase.master.port";
164
165  /** default port that the master listens on */
166  public static final int DEFAULT_MASTER_PORT = 16000;
167
168  /** default port for master web api */
169  public static final int DEFAULT_MASTER_INFOPORT = 16010;
170
171  /** Configuration key for master web API port */
172  public static final String MASTER_INFO_PORT = "hbase.master.info.port";
173
174  /** Parameter name for the master type being backup (waits for primary to go inactive). */
175  public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
176
177  /**
178   * by default every master is a possible primary master unless the conf explicitly overrides it
179   */
180  public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
181
182  /** Name of ZooKeeper quorum configuration parameter. */
183  public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
184
185  /** Name of ZooKeeper quorum configuration parameter for client to locate meta. */
186  public static final String CLIENT_ZOOKEEPER_QUORUM = "hbase.client.zookeeper.quorum";
187
188  /** Client port of ZooKeeper for client to locate meta */
189  public static final String CLIENT_ZOOKEEPER_CLIENT_PORT =
190      "hbase.client.zookeeper.property.clientPort";
191
192  /** Indicate whether the client ZK are observer nodes of the server ZK */
193  public static final String CLIENT_ZOOKEEPER_OBSERVER_MODE =
194      "hbase.client.zookeeper.observer.mode";
195  /** Assuming client zk not in observer mode and master need to synchronize information */
196  public static final boolean DEFAULT_CLIENT_ZOOKEEPER_OBSERVER_MODE = false;
197
198  /** Common prefix of ZooKeeper configuration properties */
199  public static final String ZK_CFG_PROPERTY_PREFIX =
200      "hbase.zookeeper.property.";
201
202  public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
203      ZK_CFG_PROPERTY_PREFIX.length();
204
205  /**
206   * The ZK client port key in the ZK properties map. The name reflects the
207   * fact that this is not an HBase configuration key.
208   */
209  public static final String CLIENT_PORT_STR = "clientPort";
210
211  /** Parameter name for the client port that the zookeeper listens on */
212  public static final String ZOOKEEPER_CLIENT_PORT =
213      ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
214
215  /** Default client port that the zookeeper listens on */
216  public static final int DEFAULT_ZOOKEEPER_CLIENT_PORT = 2181;
217
218  /** Parameter name for the root dir in ZK for this cluster */
219  public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
220
221  public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
222
223  /**
224   * Parameter name for the limit on concurrent client-side zookeeper
225   * connections
226   */
227  public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
228      ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
229
230  /** Parameter name for the ZK data directory */
231  public static final String ZOOKEEPER_DATA_DIR =
232      ZK_CFG_PROPERTY_PREFIX + "dataDir";
233
234  /** Parameter name for the ZK tick time */
235  public static final String ZOOKEEPER_TICK_TIME =
236      ZK_CFG_PROPERTY_PREFIX + "tickTime";
237
238  /** Default limit on concurrent client-side zookeeper connections */
239  public static final int DEFAULT_ZOOKEEPER_MAX_CLIENT_CNXNS = 300;
240
241  /** Configuration key for ZooKeeper session timeout */
242  public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
243
244  /** Default value for ZooKeeper session timeout */
245  public static final int DEFAULT_ZK_SESSION_TIMEOUT = 90 * 1000;
246
247  /** Parameter name for port region server listens on. */
248  public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
249
250  /** Default port region server listens on. */
251  public static final int DEFAULT_REGIONSERVER_PORT = 16020;
252
253  /** default port for region server web api */
254  public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
255
256  /** A configuration key for regionserver info port */
257  public static final String REGIONSERVER_INFO_PORT =
258    "hbase.regionserver.info.port";
259
260  /** A flag that enables automatic selection of regionserver info port */
261  public static final String REGIONSERVER_INFO_PORT_AUTO =
262      REGIONSERVER_INFO_PORT + ".auto";
263
264  /** Parameter name for what region server implementation to use. */
265  public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
266
267  /** Parameter name for what master implementation to use. */
268  public static final String MASTER_IMPL= "hbase.master.impl";
269
270  /** Parameter name for how often threads should wake up */
271  public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
272
273  /** Default value for thread wake frequency */
274  public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
275
276  /** Parameter name for how often we should try to write a version file, before failing */
277  public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
278
279  /** Parameter name for how often we should try to write a version file, before failing */
280  public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
281
282  /** Parameter name and default value for how often a region should perform a major compaction */
283  public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
284  public static final long   DEFAULT_MAJOR_COMPACTION_PERIOD = 1000 * 60 * 60 * 24 * 7; // 7 days
285
286  /**
287   * Parameter name and default value for major compaction jitter.
288   * Used as a multiplier applied to {@link HConstants#MAJOR_COMPACTION_PERIOD}
289   * to cause compaction to occur a given amount of time either side of
290   * {@link HConstants#MAJOR_COMPACTION_PERIOD}.
291   * Default to 0.5 so jitter has us fall evenly either side of when the compaction should run.
292   */
293  public static final String MAJOR_COMPACTION_JITTER = "hbase.hregion.majorcompaction.jitter";
294  public static final float  DEFAULT_MAJOR_COMPACTION_JITTER = 0.50F;
295
296  /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
297  public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
298  public static final int COMPACTION_KV_MAX_DEFAULT = 10;
299
300  /** Parameter name for HBase instance root directory */
301  public static final String HBASE_DIR = "hbase.rootdir";
302
303  /** Parameter name for HBase client IPC pool type */
304  public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
305
306  /** Parameter name for HBase client IPC pool size */
307  public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
308
309  /** Parameter name for HBase client operation timeout. */
310  public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
311
312  /** Parameter name for HBase client meta operation timeout. */
313  public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
314    "hbase.client.meta.operation.timeout";
315
316  /** Default HBase client operation timeout, which is tantamount to a blocking call */
317  public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = 1200000;
318
319  /** Parameter name for HBase client meta replica scan call timeout. */
320  public static final String HBASE_CLIENT_META_REPLICA_SCAN_TIMEOUT =
321      "hbase.client.meta.replica.scan.timeout";
322
323  /** Default HBase client meta replica scan call timeout, 1 second */
324  public static final int HBASE_CLIENT_META_REPLICA_SCAN_TIMEOUT_DEFAULT = 1000000;
325
326  /** Used to construct the name of the log directory for a region server */
327  public static final String HREGION_LOGDIR_NAME = "WALs";
328
329  /** Used to construct the name of the splitlog directory for a region server */
330  public static final String SPLIT_LOGDIR_NAME = "splitWAL";
331
332  /** Like the previous, but for old logs that are about to be deleted */
333  public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
334
335  /** Staging dir used by bulk load */
336  public static final String BULKLOAD_STAGING_DIR_NAME = "staging";
337
338  public static final String CORRUPT_DIR_NAME = "corrupt";
339
340  /** Used by HBCK to sideline backup data */
341  public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
342
343  /** Any artifacts left from migration can be moved here */
344  public static final String MIGRATION_NAME = ".migration";
345
346  /** Used to construct the name of the compaction directory during compaction */
347  public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
348
349  /** Conf key for the max file size after which we split the region */
350  public static final String HREGION_MAX_FILESIZE =
351      "hbase.hregion.max.filesize";
352
353  /** Default maximum file size */
354  public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
355
356  /**
357   * Max size of single row for Get's or Scan's without in-row scanning flag set.
358   */
359  public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
360
361  /**
362   * Default max row size (1 Gb).
363   */
364  public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
365
366  /**
367   * The max number of threads used for opening and closing stores or store
368   * files in parallel
369   */
370  public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
371    "hbase.hstore.open.and.close.threads.max";
372
373  /**
374   * The default number for the max number of threads used for opening and
375   * closing stores or store files in parallel
376   */
377  public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
378
379  /**
380   * Block updates if memstore has hbase.hregion.memstore.block.multiplier
381   * times hbase.hregion.memstore.flush.size bytes.  Useful preventing
382   * runaway memstore during spikes in update traffic.
383   */
384  public static final String HREGION_MEMSTORE_BLOCK_MULTIPLIER =
385          "hbase.hregion.memstore.block.multiplier";
386
387  /**
388   * Default value for hbase.hregion.memstore.block.multiplier
389   */
390  public static final int DEFAULT_HREGION_MEMSTORE_BLOCK_MULTIPLIER = 4;
391
392  /** Conf key for the memstore size at which we flush the memstore */
393  public static final String HREGION_MEMSTORE_FLUSH_SIZE =
394      "hbase.hregion.memstore.flush.size";
395
396  public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
397      "hbase.hregion.edits.replay.skip.errors";
398
399  public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
400      false;
401
402  /** Maximum value length, enforced on KeyValue construction */
403  public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
404
405  /** name of the file for unique cluster ID */
406  public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
407
408  /** Default value for cluster ID */
409  public static final String CLUSTER_ID_DEFAULT = "default-cluster";
410
411  /** Parameter name for # days to keep MVCC values during a major compaction */
412  public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
413  /** At least to keep MVCC values in hfiles for 5 days */
414  public static final int MIN_KEEP_SEQID_PERIOD = 5;
415
416  // Always store the location of the root table's HRegion.
417  // This HRegion is never split.
418
419  // region name = table + startkey + regionid. This is the row key.
420  // each row in the root and meta tables describes exactly 1 region
421  // Do we ever need to know all the information that we are storing?
422
423  // Note that the name of the root table starts with "-" and the name of the
424  // meta table starts with "." Why? it's a trick. It turns out that when we
425  // store region names in memory, we use a SortedMap. Since "-" sorts before
426  // "." (and since no other table name can start with either of these
427  // characters, the root region will always be the first entry in such a Map,
428  // followed by all the meta regions (which will be ordered by their starting
429  // row key as well), followed by all user tables. So when the Master is
430  // choosing regions to assign, it will always choose the root region first,
431  // followed by the meta regions, followed by user regions. Since the root
432  // and meta regions always need to be on-line, this ensures that they will
433  // be the first to be reassigned if the server(s) they are being served by
434  // should go down.
435
436  public static final String BASE_NAMESPACE_DIR = "data";
437
438  /** delimiter used between portions of a region name */
439  public static final int META_ROW_DELIMITER = ',';
440
441  /** The catalog family as a string*/
442  public static final String CATALOG_FAMILY_STR = "info";
443
444  /** The catalog family */
445  public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
446
447  /** The RegionInfo qualifier as a string */
448  public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
449
450  /** The regioninfo column qualifier */
451  public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
452
453  /** The server column qualifier */
454  public static final String SERVER_QUALIFIER_STR = "server";
455  /** The server column qualifier */
456  public static final byte [] SERVER_QUALIFIER = Bytes.toBytes(SERVER_QUALIFIER_STR);
457
458  /** The startcode column qualifier */
459  public static final String STARTCODE_QUALIFIER_STR = "serverstartcode";
460  /** The startcode column qualifier */
461  public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes(STARTCODE_QUALIFIER_STR);
462
463  /** The open seqnum column qualifier */
464  public static final String SEQNUM_QUALIFIER_STR = "seqnumDuringOpen";
465  /** The open seqnum column qualifier */
466  public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes(SEQNUM_QUALIFIER_STR);
467
468  /** The state column qualifier */
469  public static final String STATE_QUALIFIER_STR = "state";
470
471  public static final byte [] STATE_QUALIFIER = Bytes.toBytes(STATE_QUALIFIER_STR);
472
473  /**
474   * The serverName column qualifier. Its the server where the region is
475   * transitioning on, while column server is the server where the region is
476   * opened on. They are the same when the region is in state OPEN.
477   */
478  public static final String SERVERNAME_QUALIFIER_STR = "sn";
479
480  public static final byte [] SERVERNAME_QUALIFIER = Bytes.toBytes(SERVERNAME_QUALIFIER_STR);
481
482  /** The lower-half split region column qualifier */
483  public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
484
485  /** The upper-half split region column qualifier */
486  public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
487
488  /** The lower-half merge region column qualifier */
489  public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
490
491  /** The upper-half merge region column qualifier */
492  public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
493
494  /** The catalog family as a string*/
495  public static final String TABLE_FAMILY_STR = "table";
496
497  /** The catalog family */
498  public static final byte [] TABLE_FAMILY = Bytes.toBytes(TABLE_FAMILY_STR);
499
500  /** The serialized table state qualifier */
501  public static final byte[] TABLE_STATE_QUALIFIER = Bytes.toBytes("state");
502
503  /** The replication barrier family as a string*/
504  public static final String REPLICATION_BARRIER_FAMILY_STR = "rep_barrier";
505
506  /** The replication barrier family */
507  public static final byte[] REPLICATION_BARRIER_FAMILY =
508      Bytes.toBytes(REPLICATION_BARRIER_FAMILY_STR);
509
510  /** The namespace family as a string */
511  public static final String NAMESPACE_FAMILY_STR = "ns";
512
513  /** The namespace family */
514  public static final byte[] NAMESPACE_FAMILY = Bytes.toBytes(NAMESPACE_FAMILY_STR);
515
516  public static final byte[] NAMESPACE_COL_DESC_QUALIFIER = Bytes.toBytes("d");
517  /**
518   * The meta table version column qualifier.
519   * We keep current version of the meta table in this column in <code>-ROOT-</code>
520   * table: i.e. in the 'info:v' column.
521   */
522  public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
523
524  /**
525   * The current version of the meta table.
526   * - pre-hbase 0.92.  There is no META_VERSION column in the root table
527   * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
528   * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
529   * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
530   * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
531   * byte[] serialization from Writables to Protobuf.
532   * See HRegionInfo.VERSION
533   */
534  public static final short META_VERSION = 1;
535
536  // Other constants
537
538  /**
539   * An empty byte array instance.
540   */
541  public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
542
543  /**
544   * An empty string instance.
545   */
546  public static final String EMPTY_STRING = "";
547
548  public static final ByteBuffer EMPTY_BYTE_BUFFER = ByteBuffer.wrap(EMPTY_BYTE_ARRAY);
549
550  /**
551   * Used by scanners, etc when they want to start at the beginning of a region
552   */
553  public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
554
555  /**
556   * Last row in a table.
557   */
558  public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
559
560  /**
561    * Used by scanners and others when they're trying to detect the end of a
562    * table
563    */
564  public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
565
566  /**
567   * Max length a row can have because of the limitation in TFile.
568   */
569  public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
570
571  /**
572   * Timestamp to use when we want to refer to the latest cell.
573   *
574   * On client side, this is the timestamp set by default when no timestamp is specified,
575   * to refer to the latest.
576   * On server side, this acts as a notation.
577   * (1) For a cell of Put, which has this notation,
578   *     its timestamp will be replaced with server's current time.
579   * (2) For a cell of Delete, which has this notation,
580   *     A. If the cell is of {@link KeyValue.Type#Delete}, HBase issues a Get operation firstly.
581   *        a. When the count of cell it gets is less than the count of cell to delete,
582   *           the timestamp of Delete cell will be replaced with server's current time.
583   *        b. When the count of cell it gets is equal to the count of cell to delete,
584   *           the timestamp of Delete cell will be replaced with the latest timestamp of cell it
585   *           gets.
586   *       (c. It is invalid and an exception will be thrown,
587   *           if the count of cell it gets is greater than the count of cell to delete,
588   *           as the max version of Get is set to the count of cell to delete.)
589   *     B. If the cell is of other Delete types, like {@link KeyValue.Type#DeleteFamilyVersion},
590   *        {@link KeyValue.Type#DeleteColumn}, or {@link KeyValue.Type#DeleteFamily},
591   *        the timestamp of Delete cell will be replaced with server's current time.
592   *
593   * So that is why it is named as "latest" but assigned as the max value of Long.
594   */
595  public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
596
597  /**
598   * Timestamp to use when we want to refer to the oldest cell.
599   * Special! Used in fake Cells only. Should never be the timestamp on an actual Cell returned to
600   * a client.
601   * @deprecated Should not be public since hbase-1.3.0. For internal use only. Move internal to
602   *   Scanners flagged as special timestamp value never to be returned as timestamp on a Cell.
603   */
604  @Deprecated
605  public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
606
607  /**
608   * LATEST_TIMESTAMP in bytes form
609   */
610  public static final byte [] LATEST_TIMESTAMP_BYTES = {
611    // big-endian
612    (byte) (LATEST_TIMESTAMP >>> 56),
613    (byte) (LATEST_TIMESTAMP >>> 48),
614    (byte) (LATEST_TIMESTAMP >>> 40),
615    (byte) (LATEST_TIMESTAMP >>> 32),
616    (byte) (LATEST_TIMESTAMP >>> 24),
617    (byte) (LATEST_TIMESTAMP >>> 16),
618    (byte) (LATEST_TIMESTAMP >>> 8),
619    (byte) LATEST_TIMESTAMP,
620  };
621
622  /**
623   * Define for 'return-all-versions'.
624   */
625  public static final int ALL_VERSIONS = Integer.MAX_VALUE;
626
627  /**
628   * Unlimited time-to-live.
629   */
630//  public static final int FOREVER = -1;
631  public static final int FOREVER = Integer.MAX_VALUE;
632
633  /**
634   * Seconds in a day, hour and minute
635   */
636  public static final int DAY_IN_SECONDS = 24 * 60 * 60;
637  public static final int HOUR_IN_SECONDS = 60 * 60;
638  public static final int MINUTE_IN_SECONDS = 60;
639
640  //TODO: although the following are referenced widely to format strings for
641  //      the shell. They really aren't a part of the public API. It would be
642  //      nice if we could put them somewhere where they did not need to be
643  //      public. They could have package visibility
644  public static final String NAME = "NAME";
645  public static final String VERSIONS = "VERSIONS";
646  public static final String IN_MEMORY = "IN_MEMORY";
647  public static final String METADATA = "METADATA";
648  public static final String CONFIGURATION = "CONFIGURATION";
649
650  /**
651   * Retrying we multiply hbase.client.pause setting by what we have in this array until we
652   * run out of array items.  Retries beyond this use the last number in the array.  So, for
653   * example, if hbase.client.pause is 1 second, and maximum retries count
654   * hbase.client.retries.number is 10, we will retry at the following intervals:
655   * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
656   * With 100ms, a back-off of 200 means 20s
657   */
658  public static final int [] RETRY_BACKOFF = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
659
660  public static final String REGION_IMPL = "hbase.hregion.impl";
661
662  /**
663   * Scope tag for locally scoped data.
664   * This data will not be replicated.
665   */
666  public static final int REPLICATION_SCOPE_LOCAL = 0;
667
668  /**
669   * Scope tag for globally scoped data.
670   * This data will be replicated to all peers.
671   */
672  public static final int REPLICATION_SCOPE_GLOBAL = 1;
673
674  /**
675   * Default cluster ID, cannot be used to identify a cluster so a key with
676   * this value means it wasn't meant for replication.
677   */
678  public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
679
680  /**
681   * Parameter name for maximum number of bytes returned when calling a scanner's next method.
682   * Controlled by the client.
683   */
684  public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
685      "hbase.client.scanner.max.result.size";
686
687  /**
688   * Parameter name for maximum number of bytes returned when calling a scanner's next method.
689   * Controlled by the server.
690   */
691  public static final String HBASE_SERVER_SCANNER_MAX_RESULT_SIZE_KEY =
692      "hbase.server.scanner.max.result.size";
693
694  /**
695   * Maximum number of bytes returned when calling a scanner's next method.
696   * Note that when a single row is larger than this limit the row is still
697   * returned completely.
698   *
699   * The default value is 2MB.
700   */
701  public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
702
703  /**
704   * Maximum number of bytes returned when calling a scanner's next method.
705   * Note that when a single row is larger than this limit the row is still
706   * returned completely.
707   * Safety setting to protect the region server.
708   *
709   * The default value is 100MB. (a client would rarely request larger chunks on purpose)
710   */
711  public static final long DEFAULT_HBASE_SERVER_SCANNER_MAX_RESULT_SIZE = 100 * 1024 * 1024;
712
713  /**
714   * Parameter name for client pause value, used mostly as value to wait
715   * before running a retry of a failed get, region lookup, etc.
716   */
717  public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
718
719  /**
720   * Default value of {@link #HBASE_CLIENT_PAUSE}.
721   */
722  public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
723
724  /**
725   * Parameter name for client pause value for special case such as call queue too big, etc.
726   */
727  public static final String HBASE_CLIENT_PAUSE_FOR_CQTBE = "hbase.client.pause.cqtbe";
728
729  /**
730   * The maximum number of concurrent connections the client will maintain.
731   */
732  public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
733
734  /**
735   * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
736   */
737  public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
738
739  /**
740   * The maximum number of concurrent connections the client will maintain to a single
741   * RegionServer.
742   */
743  public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
744
745  /**
746   * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
747   */
748  public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
749
750  /**
751   * The maximum number of concurrent connections the client will maintain to a single
752   * Region.
753   */
754  public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
755
756  /**
757   * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
758   */
759  public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
760
761  /**
762   * The maximum number of concurrent pending RPC requests for one server in process level.
763   */
764  public static final String HBASE_CLIENT_PERSERVER_REQUESTS_THRESHOLD =
765      "hbase.client.perserver.requests.threshold";
766
767  /**
768   * Default value of {@link #HBASE_CLIENT_PERSERVER_REQUESTS_THRESHOLD}.
769   */
770  public static final int DEFAULT_HBASE_CLIENT_PERSERVER_REQUESTS_THRESHOLD = Integer.MAX_VALUE;
771
772
773  /**
774   * Parameter name for server pause value, used mostly as value to wait before
775   * running a retry of a failed operation.
776   */
777  public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
778
779  /**
780   * Default value of {@link #HBASE_SERVER_PAUSE}.
781   */
782  public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
783
784  /**
785   * Parameter name for maximum retries, used as maximum for all retryable
786   * operations such as fetching of the root region from root region server,
787   * getting a cell's value, starting a row update, etc.
788   */
789  public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
790
791  /**
792   * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
793   */
794  public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 15;
795
796  public static final String HBASE_CLIENT_SERVERSIDE_RETRIES_MULTIPLIER =
797      "hbase.client.serverside.retries.multiplier";
798
799  public static final int DEFAULT_HBASE_CLIENT_SERVERSIDE_RETRIES_MULTIPLIER = 3;
800
801  /**
802   * Parameter name to set the default scanner caching for all clients.
803   */
804  public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
805
806  /**
807   * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
808   */
809  public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = Integer.MAX_VALUE;
810
811  /**
812   * Parameter name for number of rows that will be fetched when calling next on
813   * a scanner if it is not served from memory. Higher caching values will
814   * enable faster scanners but will eat up more memory and some calls of next
815   * may take longer and longer times when the cache is empty.
816   */
817  public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
818
819  /**
820   * Default value of {@link #HBASE_META_SCANNER_CACHING}.
821   */
822  public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
823
824  /**
825   * Parameter name for number of versions, kept by meta table.
826   */
827  public static final String HBASE_META_VERSIONS = "hbase.meta.versions";
828
829  /**
830   * Default value of {@link #HBASE_META_VERSIONS}.
831   */
832  public static final int DEFAULT_HBASE_META_VERSIONS = 3;
833
834  /**
835   * Parameter name for number of versions, kept by meta table.
836   */
837  public static final String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
838
839  /**
840   * Default value of {@link #HBASE_META_BLOCK_SIZE}.
841   */
842  public static final int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
843
844  /**
845   * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
846   * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
847   * for all intents and purposes, are the same except for their instance ids, then they will not be
848   * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
849   * even if the instance ids are the same, it could result in non-shared
850   * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
851   * differ.
852   */
853  public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
854
855  /**
856   * The client scanner timeout period in milliseconds.
857   */
858  public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD =
859      "hbase.client.scanner.timeout.period";
860
861  /**
862   * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
863   * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
864   */
865  @Deprecated
866  public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
867      "hbase.regionserver.lease.period";
868
869  /**
870   * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
871   */
872  public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
873
874  /**
875   * timeout for each RPC
876   */
877  public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
878
879  /**
880   * timeout for each read RPC
881   */
882  public static final String HBASE_RPC_READ_TIMEOUT_KEY = "hbase.rpc.read.timeout";
883
884  /**
885   * timeout for each write RPC
886   */
887  public static final String HBASE_RPC_WRITE_TIMEOUT_KEY = "hbase.rpc.write.timeout";
888
889  /**
890   * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
891   */
892  public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
893
894  /**
895   * timeout for short operation RPC
896   */
897  public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY =
898      "hbase.rpc.shortoperation.timeout";
899
900  /**
901   * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
902   */
903  public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
904
905  /**
906   * Value indicating the server name was saved with no sequence number.
907   */
908  public static final long NO_SEQNUM = -1;
909
910
911  /*
912   * cluster replication constants.
913   */
914  public static final String
915      REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
916  public static final String
917      REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
918  public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
919    "org.apache.hadoop.hbase.replication.regionserver.Replication";
920  public static final String REPLICATION_BULKLOAD_ENABLE_KEY = "hbase.replication.bulkload.enabled";
921  public static final boolean REPLICATION_BULKLOAD_ENABLE_DEFAULT = false;
922  /** Replication cluster id of source cluster which uniquely identifies itself with peer cluster */
923  public static final String REPLICATION_CLUSTER_ID = "hbase.replication.cluster.id";
924  /**
925   * Max total size of buffered entries in all replication peers. It will prevent server getting
926   * OOM if there are many peers. Default value is 256MB which is four times to default
927   * replication.source.size.capacity.
928   */
929  public static final String REPLICATION_SOURCE_TOTAL_BUFFER_KEY = "replication.total.buffer.quota";
930
931  public static final int REPLICATION_SOURCE_TOTAL_BUFFER_DFAULT = 256 * 1024 * 1024;
932
933
934  /**
935   * Directory where the source cluster file system client configuration are placed which is used by
936   * sink cluster to copy HFiles from source cluster file system
937   */
938  public static final String REPLICATION_CONF_DIR = "hbase.replication.conf.dir";
939
940  /** Maximum time to retry for a failed bulk load request */
941  public static final String BULKLOAD_MAX_RETRIES_NUMBER = "hbase.bulkload.retries.number";
942
943  public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
944    "hbase.regionserver.hostname.seen.by.master";
945
946  public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
947      "hbase.master.logcleaner.plugins";
948
949  public static final String HBASE_REGION_SPLIT_POLICY_KEY =
950    "hbase.regionserver.region.split.policy";
951
952  /** Whether nonces are enabled; default is true. */
953  public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
954
955  /**
956   * Configuration key for the size of the block cache
957   */
958  public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
959    "hfile.block.cache.size";
960
961  public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
962
963  /*
964    * Minimum percentage of free heap necessary for a successful cluster startup.
965    */
966  public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
967
968  /**
969   * @deprecated  It is used internally. As of release 2.0.0, this will be removed in HBase 3.0.0.
970   */
971  @Deprecated
972  public static final Pattern CP_HTD_ATTR_KEY_PATTERN =
973      Pattern.compile("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
974
975  /**
976   * <pre>
977   * Pattern that matches a coprocessor specification. Form is:
978   * {@code <coprocessor jar file location> '|' <class name> ['|' <priority> ['|' <arguments>]]}
979   * where arguments are {@code <KEY> '=' <VALUE> [,...]}
980   * For example: {@code hdfs:///foo.jar|com.foo.FooRegionObserver|1001|arg1=1,arg2=2}
981   * </pre>
982   * @deprecated  It is used internally. As of release 2.0.0, this will be removed in HBase 3.0.0.
983   */
984  @Deprecated
985  public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
986      Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
987  /**
988   * @deprecated  It is used internally. As of release 2.0.0, this will be removed in HBase 3.0.0.
989   */
990  @Deprecated
991  public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
992  /**
993   * @deprecated  It is used internally. As of release 2.0.0, this will be removed in HBase 3.0.0.
994   */
995  @Deprecated
996  public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
997  /**
998   * @deprecated  It is used internally. As of release 2.0.0, this will be removed in HBase 3.0.0.
999   */
1000  @Deprecated
1001  public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
1002      "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
1003      CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
1004  public static final String CP_HTD_ATTR_INCLUSION_KEY =
1005      "hbase.coprocessor.classloader.included.classes";
1006
1007  /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
1008  public static final int SOCKET_RETRY_WAIT_MS = 200;
1009
1010  /** Host name of the local machine */
1011  public static final String LOCALHOST = "localhost";
1012
1013  /**
1014   * If this parameter is set to true, then hbase will read
1015   * data and then verify checksums. Checksum verification
1016   * inside hdfs will be switched off.  However, if the hbase-checksum
1017   * verification fails, then it will switch back to using
1018   * hdfs checksums for verifiying data that is being read from storage.
1019   *
1020   * If this parameter is set to false, then hbase will not
1021   * verify any checksums, instead it will depend on checksum verification
1022   * being done in the hdfs client.
1023   */
1024  public static final String HBASE_CHECKSUM_VERIFICATION =
1025      "hbase.regionserver.checksum.verify";
1026
1027  public static final String LOCALHOST_IP = "127.0.0.1";
1028
1029  public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
1030  public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
1031
1032  /*
1033   * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
1034   * -1  => Disable aborting
1035   * 0   => Abort if even a single handler has died
1036   * 0.x => Abort only when this percent of handlers have died
1037   * 1   => Abort only all of the handers have died
1038   */
1039  public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
1040      "hbase.regionserver.handler.abort.on.error.percent";
1041  public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
1042
1043  //High priority handlers to deal with admin requests and system table operation requests
1044  public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
1045      "hbase.regionserver.metahandler.count";
1046  public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 20;
1047
1048  public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
1049      "hbase.regionserver.replication.handler.count";
1050  public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
1051  // Meta Transition handlers to deal with meta ReportRegionStateTransitionRequest. Meta transition
1052  // should be dealt with in a separate handler in case blocking other region's transition.
1053  public static final String MASTER_META_TRANSITION_HANDLER_COUNT =
1054      "hbase.master.meta.transition.handler.count";
1055  public static final int MASTER__META_TRANSITION_HANDLER_COUNT_DEFAULT = 1;
1056
1057  /** Conf key for enabling meta replication */
1058  public static final String USE_META_REPLICAS = "hbase.meta.replicas.use";
1059  public static final boolean DEFAULT_USE_META_REPLICAS = false;
1060  public static final String META_REPLICAS_NUM = "hbase.meta.replica.count";
1061  public static final int DEFAULT_META_REPLICA_NUM = 1;
1062
1063  /**
1064   * The name of the configuration parameter that specifies
1065   * the number of bytes in a newly created checksum chunk.
1066   */
1067  public static final String BYTES_PER_CHECKSUM =
1068      "hbase.hstore.bytes.per.checksum";
1069
1070  /**
1071   * The name of the configuration parameter that specifies
1072   * the name of an algorithm that is used to compute checksums
1073   * for newly created blocks.
1074   */
1075  public static final String CHECKSUM_TYPE_NAME =
1076      "hbase.hstore.checksum.algorithm";
1077
1078  /** Enable file permission modification from standard hbase */
1079  public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
1080  /** File permission umask to use when creating hbase data files */
1081  public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
1082
1083  /** Configuration name of WAL Compression */
1084  public static final String ENABLE_WAL_COMPRESSION =
1085    "hbase.regionserver.wal.enablecompression";
1086
1087  /** Configuration name of WAL storage policy
1088   * Valid values are: HOT, COLD, WARM, ALL_SSD, ONE_SSD, LAZY_PERSIST
1089   * See http://hadoop.apache.org/docs/r2.7.3/hadoop-project-dist/hadoop-hdfs/ArchivalStorage.html*/
1090  public static final String WAL_STORAGE_POLICY = "hbase.wal.storage.policy";
1091  /**
1092   * "NONE" is not a valid storage policy and means we defer the policy to HDFS. @see
1093   * <a href="https://issues.apache.org/jira/browse/HBASE-20691">HBASE-20691</a>
1094   */
1095  public static final String DEFER_TO_HDFS_STORAGE_POLICY = "NONE";
1096  /** By default we defer the WAL storage policy to HDFS */
1097  public static final String DEFAULT_WAL_STORAGE_POLICY = DEFER_TO_HDFS_STORAGE_POLICY;
1098
1099  /** Region in Transition metrics threshold time */
1100  public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD =
1101      "hbase.metrics.rit.stuck.warning.threshold";
1102
1103  public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
1104
1105  /** delimiter used between portions of a region name */
1106  public static final int DELIMITER = ',';
1107
1108  /**
1109   * QOS attributes: these attributes are used to demarcate RPC call processing
1110   * by different set of handlers. For example, HIGH_QOS tagged methods are
1111   * handled by high priority handlers.
1112   */
1113  // normal_QOS < replication_QOS < replay_QOS < QOS_threshold < admin_QOS < high_QOS < meta_QOS
1114  public static final int PRIORITY_UNSET = -1;
1115  public static final int NORMAL_QOS = 0;
1116  public static final int REPLICATION_QOS = 5;
1117  public static final int REPLAY_QOS = 6;
1118  public static final int QOS_THRESHOLD = 10;
1119  public static final int ADMIN_QOS = 100;
1120  public static final int HIGH_QOS = 200;
1121  public static final int SYSTEMTABLE_QOS = HIGH_QOS;
1122  /**
1123   * @deprecated the name "META_QOS" is a bit ambiguous, actually only meta region transition can
1124   *             use this priority, and you should not use this directly. Will be removed in 3.0.0.
1125   */
1126  @Deprecated
1127  public static final int META_QOS = 300;
1128
1129  /** Directory under /hbase where archived hfiles are stored */
1130  public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
1131
1132  /**
1133   * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
1134   * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
1135   * uni-directional.
1136   */
1137  public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
1138
1139  /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
1140  public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
1141
1142  /** Temporary directory used for table creation and deletion */
1143  public static final String HBASE_TEMP_DIRECTORY = ".tmp";
1144  /**
1145   * The period (in milliseconds) between computing region server point in time metrics
1146   */
1147  public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
1148  public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
1149  /** Directories that are not HBase table directories */
1150  public static final List<String> HBASE_NON_TABLE_DIRS =
1151    Collections.unmodifiableList(Arrays.asList(new String[] {
1152      HBCK_SIDELINEDIR_NAME, HBASE_TEMP_DIRECTORY, MIGRATION_NAME
1153    }));
1154
1155  /** Directories that are not HBase user table directories */
1156  public static final List<String> HBASE_NON_USER_TABLE_DIRS =
1157    Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
1158      new String[] { TableName.META_TABLE_NAME.getNameAsString() },
1159      HBASE_NON_TABLE_DIRS.toArray())));
1160
1161  /** Health script related settings. */
1162  public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
1163  public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
1164  public static final String HEALTH_CHORE_WAKE_FREQ =
1165      "hbase.node.health.script.frequency";
1166  public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
1167  /**
1168   * The maximum number of health check failures a server can encounter consecutively.
1169   */
1170  public static final String HEALTH_FAILURE_THRESHOLD =
1171      "hbase.node.health.failure.threshold";
1172  public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
1173
1174
1175  /**
1176   * Setting to activate, or not, the publication of the status by the master. Default
1177   *  notification is by a multicast message.
1178   */
1179  public static final String STATUS_PUBLISHED = "hbase.status.published";
1180  public static final boolean STATUS_PUBLISHED_DEFAULT = false;
1181
1182  /**
1183   * IP to use for the multicast status messages between the master and the clients.
1184   * The default address is chosen as one among others within the ones suitable for multicast
1185   * messages.
1186   */
1187  public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
1188  public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
1189
1190  /**
1191   * The address to use for binding the local socket for receiving multicast. Defaults to
1192   * 0.0.0.0.
1193   * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
1194   */
1195  public static final String STATUS_MULTICAST_BIND_ADDRESS =
1196      "hbase.status.multicast.bind.address.ip";
1197  public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
1198
1199  /**
1200   * The port to use for the multicast messages.
1201   */
1202  public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
1203  public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
1204
1205  /**
1206   * The network interface name to use for the multicast messages.
1207   */
1208  public static final String STATUS_MULTICAST_NI_NAME = "hbase.status.multicast.ni.name";
1209
1210  /**
1211   * The address to use for binding the local socket for sending multicast. Defaults to 0.0.0.0.
1212   */
1213  public static final String STATUS_MULTICAST_PUBLISHER_BIND_ADDRESS =
1214    "hbase.status.multicast.publisher.bind.address.ip";
1215  public static final String DEFAULT_STATUS_MULTICAST_PUBLISHER_BIND_ADDRESS = "0.0.0.0";
1216
1217  public static final long NO_NONCE = 0;
1218
1219  /** Default cipher for encryption */
1220  public static final String CIPHER_AES = "AES";
1221
1222  /** Configuration key for the crypto algorithm provider, a class name */
1223  public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
1224
1225  /** Configuration key for the crypto key provider, a class name */
1226  public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
1227
1228  /** Configuration key for the crypto key provider parameters */
1229  public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
1230      "hbase.crypto.keyprovider.parameters";
1231
1232  /** Configuration key for the name of the master key for the cluster, a string */
1233  public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
1234
1235  /** Configuration key for the name of the alternate master key for the cluster, a string */
1236  public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
1237    "hbase.crypto.master.alternate.key.name";
1238
1239  /** Configuration key for the algorithm to use when encrypting the WAL, a string */
1240  public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
1241
1242  /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
1243  public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
1244
1245  /** Configuration key for the algorithm used for creating jks key, a string */
1246  public static final String CRYPTO_KEY_ALGORITHM_CONF_KEY = "hbase.crypto.key.algorithm";
1247
1248  /** Configuration key for the name of the alternate cipher algorithm for the cluster, a string */
1249  public static final String CRYPTO_ALTERNATE_KEY_ALGORITHM_CONF_KEY =
1250      "hbase.crypto.alternate.key.algorithm";
1251
1252  /** Configuration key for enabling WAL encryption, a boolean */
1253  public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
1254
1255  /** Configuration key for setting RPC codec class name */
1256  public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
1257
1258  /** Configuration key for setting replication codec class name */
1259  public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
1260
1261  /** Maximum number of threads used by the replication source for shipping edits to the sinks */
1262  public static final String REPLICATION_SOURCE_MAXTHREADS_KEY =
1263      "hbase.replication.source.maxthreads";
1264
1265  /** Drop edits for tables that been deleted from the replication source and target */
1266  public static final String REPLICATION_DROP_ON_DELETED_TABLE_KEY =
1267      "hbase.replication.drop.on.deleted.table";
1268
1269  /** Maximum number of threads used by the replication source for shipping edits to the sinks */
1270  public static final int REPLICATION_SOURCE_MAXTHREADS_DEFAULT = 10;
1271
1272  /** Configuration key for SplitLog manager timeout */
1273  public static final String HBASE_SPLITLOG_MANAGER_TIMEOUT = "hbase.splitlog.manager.timeout";
1274
1275  /**
1276   * Configuration keys for Bucket cache
1277   */
1278  // TODO moving these bucket cache implementation specific configs to this level is violation of
1279  // encapsulation. But as these has to be referred from hbase-common and bucket cache
1280  // sits in hbase-server, there were no other go! Can we move the cache implementation to
1281  // hbase-common?
1282
1283  /**
1284   * Current ioengine options in include: heap, offheap and file:PATH (where PATH is the path
1285   * to the file that will host the file-based cache.  See BucketCache#getIOEngineFromName() for
1286   * list of supported ioengine options.
1287   * <p>Set this option and a non-zero {@link #BUCKET_CACHE_SIZE_KEY} to enable bucket cache.
1288   */
1289  public static final String BUCKET_CACHE_IOENGINE_KEY = "hbase.bucketcache.ioengine";
1290
1291  /**
1292   * When using bucket cache, this is a float that EITHER represents a percentage of total heap
1293   * memory size to give to the cache (if &lt; 1.0) OR, it is the capacity in
1294   * megabytes of the cache.
1295   */
1296  public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1297
1298  /**
1299   * HConstants for fast fail on the client side follow
1300   */
1301  /**
1302   * Config for enabling/disabling the fast fail mode.
1303   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1304   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1305   */
1306  @Deprecated
1307  public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1308    "hbase.client.fast.fail.mode.enabled";
1309
1310  /**
1311   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1312   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1313   */
1314  @Deprecated
1315  public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT = false;
1316
1317  /**
1318   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1319   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1320   */
1321  @Deprecated
1322  public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1323    "hbase.client.fastfail.threshold";
1324
1325  /**
1326   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1327   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1328   */
1329  @Deprecated
1330  public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT = 60000;
1331
1332  /**
1333   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1334   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1335   */
1336  @Deprecated
1337  public static final String HBASE_CLIENT_FAILURE_MAP_CLEANUP_INTERVAL_MS =
1338    "hbase.client.failure.map.cleanup.interval";
1339
1340  /**
1341   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1342   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1343   */
1344  @Deprecated
1345  public static final long HBASE_CLIENT_FAILURE_MAP_CLEANUP_INTERVAL_MS_DEFAULT = 600000;
1346
1347  /**
1348   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1349   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1350   */
1351  @Deprecated
1352  public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1353    "hbase.client.fast.fail.cleanup.duration";
1354
1355  /**
1356   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1357   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1358   */
1359  @Deprecated
1360  public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT = 600000;
1361
1362  /**
1363   * @deprecated since 2.3.0, and in 3.0.0 the actually implementation will be removed so config
1364   *             this value will have no effect. The constants itself will be removed in 4.0.0.
1365   */
1366  @Deprecated
1367  public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1368    "hbase.client.fast.fail.interceptor.impl";
1369
1370  public static final String HBASE_SPLIT_WAL_COORDINATED_BY_ZK = "hbase.split.wal.zk.coordinated";
1371
1372  public static final boolean DEFAULT_HBASE_SPLIT_COORDINATED_BY_ZK = true;
1373
1374  public static final String HBASE_SPLIT_WAL_MAX_SPLITTER = "hbase.regionserver.wal.max.splitters";
1375
1376  public static final int DEFAULT_HBASE_SPLIT_WAL_MAX_SPLITTER = 2;
1377
1378  /** Config key for if the server should send backpressure and if the client should listen to
1379   * that backpressure from the server */
1380  public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1381  public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1382
1383  public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1384      "hbase.heap.occupancy.low_water_mark";
1385  public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1386  public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1387      "hbase.heap.occupancy.high_water_mark";
1388  public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1389
1390  /**
1391   * The max number of threads used for splitting storefiles in parallel during
1392   * the region split process.
1393   */
1394  public static final String REGION_SPLIT_THREADS_MAX =
1395    "hbase.regionserver.region.split.threads.max";
1396
1397  /** Canary config keys */
1398  // TODO: Move these defines to Canary Class
1399  public static final String HBASE_CANARY_WRITE_DATA_TTL_KEY = "hbase.canary.write.data.ttl";
1400
1401  public static final String HBASE_CANARY_WRITE_PERSERVER_REGIONS_LOWERLIMIT_KEY =
1402      "hbase.canary.write.perserver.regions.lowerLimit";
1403
1404  public static final String HBASE_CANARY_WRITE_PERSERVER_REGIONS_UPPERLIMIT_KEY =
1405      "hbase.canary.write.perserver.regions.upperLimit";
1406
1407  public static final String HBASE_CANARY_WRITE_VALUE_SIZE_KEY = "hbase.canary.write.value.size";
1408
1409  public static final String HBASE_CANARY_WRITE_TABLE_CHECK_PERIOD_KEY =
1410      "hbase.canary.write.table.check.period";
1411
1412  public static final String HBASE_CANARY_READ_RAW_SCAN_KEY = "hbase.canary.read.raw.enabled";
1413
1414  /**
1415   * Configuration keys for programmatic JAAS configuration for secured ZK interaction
1416   */
1417  public static final String ZK_CLIENT_KEYTAB_FILE = "hbase.zookeeper.client.keytab.file";
1418  public static final String ZK_CLIENT_KERBEROS_PRINCIPAL =
1419      "hbase.zookeeper.client.kerberos.principal";
1420  public static final String ZK_SERVER_KEYTAB_FILE = "hbase.zookeeper.server.keytab.file";
1421  public static final String ZK_SERVER_KERBEROS_PRINCIPAL =
1422      "hbase.zookeeper.server.kerberos.principal";
1423
1424  /** Config key for hbase temporary directory in hdfs */
1425  public static final String TEMPORARY_FS_DIRECTORY_KEY = "hbase.fs.tmp.dir";
1426
1427  /**
1428   * Don't use it! This'll get you the wrong path in a secure cluster.
1429   * Use FileSystem.getHomeDirectory() or
1430   * "/user/" + UserGroupInformation.getCurrentUser().getShortUserName()
1431   */
1432  public static final String DEFAULT_TEMPORARY_HDFS_DIRECTORY = "/user/"
1433      + System.getProperty("user.name") + "/hbase-staging";
1434
1435  public static final String SNAPSHOT_RESTORE_TAKE_FAILSAFE_SNAPSHOT =
1436      "hbase.snapshot.restore.take.failsafe.snapshot";
1437  public static final boolean DEFAULT_SNAPSHOT_RESTORE_TAKE_FAILSAFE_SNAPSHOT = true;
1438
1439  public static final String SNAPSHOT_RESTORE_FAILSAFE_NAME =
1440      "hbase.snapshot.restore.failsafe.name";
1441  public static final String DEFAULT_SNAPSHOT_RESTORE_FAILSAFE_NAME =
1442      "hbase-failsafe-{snapshot.name}-{restore.timestamp}";
1443
1444  public static final String DEFAULT_LOSSY_COUNTING_ERROR_RATE =
1445      "hbase.util.default.lossycounting.errorrate";
1446  public static final String NOT_IMPLEMENTED = "Not implemented";
1447
1448  private HConstants() {
1449    // Can't be instantiated with this ctor.
1450  }
1451}