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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase;
19  
20  import static org.apache.hadoop.hbase.io.hfile.BlockType.MAGIC_LENGTH;
21  
22  import java.nio.ByteBuffer;
23  import java.nio.charset.Charset;
24  import java.util.Arrays;
25  import java.util.Collections;
26  import java.util.List;
27  import java.util.UUID;
28  import java.util.regex.Pattern;
29  
30  import org.apache.commons.lang.ArrayUtils;
31  import org.apache.hadoop.hbase.classification.InterfaceAudience;
32  import org.apache.hadoop.hbase.classification.InterfaceStability;
33  import org.apache.hadoop.hbase.util.Bytes;
34  
35  /**
36   * HConstants holds a bunch of HBase-related constants
37   */
38  @InterfaceAudience.Public
39  @InterfaceStability.Stable
40  public final class HConstants {
41    // NOTICE!!!! Please do not add a constants here, unless they are referenced by a lot of classes.
42  
43    //Bytes.UTF8_ENCODING should be updated if this changed
44    /** When we encode strings, we always specify UTF8 encoding */
45    public static final String UTF8_ENCODING = "UTF-8";
46  
47    //Bytes.UTF8_CHARSET should be updated if this changed
48    /** When we encode strings, we always specify UTF8 encoding */
49    public static final Charset UTF8_CHARSET = Charset.forName(UTF8_ENCODING);
50    /**
51     * Default block size for an HFile.
52     */
53    public final static int DEFAULT_BLOCKSIZE = 64 * 1024;
54  
55    /** Used as a magic return value while optimized index key feature enabled(HBASE-7845) */
56    public final static int INDEX_KEY_MAGIC = -2;
57    /*
58       * Name of directory that holds recovered edits written by the wal log
59       * splitting code, one per region
60       */
61    public static final String RECOVERED_EDITS_DIR = "recovered.edits";
62    /**
63     * The first four bytes of Hadoop RPC connections
64     */
65    public static final ByteBuffer RPC_HEADER = ByteBuffer.wrap("HBas".getBytes());
66    public static final byte RPC_CURRENT_VERSION = 0;
67  
68    // HFileBlock constants.
69  
70    /** The size data structures with minor version is 0 */
71    public static final int HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM = MAGIC_LENGTH + 2 * Bytes.SIZEOF_INT
72        + Bytes.SIZEOF_LONG;
73    /** The size of a version 2 HFile block header, minor version 1.
74     * There is a 1 byte checksum type, followed by a 4 byte bytesPerChecksum
75     * followed by another 4 byte value to store sizeofDataOnDisk.
76     */
77    public static final int HFILEBLOCK_HEADER_SIZE = HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM +
78      Bytes.SIZEOF_BYTE + 2 * Bytes.SIZEOF_INT;
79    /** Just an array of bytes of the right size. */
80    public static final byte[] HFILEBLOCK_DUMMY_HEADER = new byte[HFILEBLOCK_HEADER_SIZE];
81  
82    //End HFileBlockConstants.
83  
84    /**
85     * Status codes used for return values of bulk operations.
86     */
87    @InterfaceAudience.Private
88    public enum OperationStatusCode {
89      NOT_RUN,
90      SUCCESS,
91      BAD_FAMILY,
92      SANITY_CHECK_FAILURE,
93      FAILURE;
94    }
95  
96    /** long constant for zero */
97    public static final Long ZERO_L = Long.valueOf(0L);
98    public static final String NINES = "99999999999999";
99    public static final String ZEROES = "00000000000000";
100 
101   // For migration
102 
103   /** name of version file */
104   public static final String VERSION_FILE_NAME = "hbase.version";
105 
106   /**
107    * Current version of file system.
108    * Version 4 supports only one kind of bloom filter.
109    * Version 5 changes versions in catalog table regions.
110    * Version 6 enables blockcaching on catalog tables.
111    * Version 7 introduces hfile -- hbase 0.19 to 0.20..
112    * Version 8 introduces namespace
113    */
114   // public static final String FILE_SYSTEM_VERSION = "6";
115   public static final String FILE_SYSTEM_VERSION = "8";
116 
117   // Configuration parameters
118 
119   //TODO: Is having HBase homed on port 60k OK?
120 
121   /** Cluster is in distributed mode or not */
122   public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";
123 
124   /** Config for pluggable load balancers */
125   public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";
126 
127   /** Cluster is standalone or pseudo-distributed */
128   public static final boolean CLUSTER_IS_LOCAL = false;
129 
130   /** Cluster is fully-distributed */
131   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
132 
133   /** Default value for cluster distributed mode */
134   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
135 
136   /** default host address */
137   public static final String DEFAULT_HOST = "0.0.0.0";
138 
139   /** Parameter name for port master listens on. */
140   public static final String MASTER_PORT = "hbase.master.port";
141 
142   /** default port that the master listens on */
143   public static final int DEFAULT_MASTER_PORT = 16000;
144 
145   /** default port for master web api */
146   public static final int DEFAULT_MASTER_INFOPORT = 16010;
147 
148   /** Configuration key for master web API port */
149   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
150 
151   /** Parameter name for the master type being backup (waits for primary to go inactive). */
152   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
153 
154   /** by default every master is a possible primary master unless the conf explicitly overrides it */
155   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
156 
157   /** Name of ZooKeeper quorum configuration parameter. */
158   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
159 
160   /** Name of ZooKeeper config file in conf/ directory. */
161   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
162 
163   /** Common prefix of ZooKeeper configuration properties */
164   public static final String ZK_CFG_PROPERTY_PREFIX =
165       "hbase.zookeeper.property.";
166 
167   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
168       ZK_CFG_PROPERTY_PREFIX.length();
169 
170   /**
171    * The ZK client port key in the ZK properties map. The name reflects the
172    * fact that this is not an HBase configuration key.
173    */
174   public static final String CLIENT_PORT_STR = "clientPort";
175 
176   /** Parameter name for the client port that the zookeeper listens on */
177   public static final String ZOOKEEPER_CLIENT_PORT =
178       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
179 
180   /** Default client port that the zookeeper listens on */
181   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
182 
183   /** Parameter name for the wait time for the recoverable zookeeper */
184   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";
185 
186   /** Default wait time for the recoverable zookeeper */
187   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
188 
189   /** Parameter name for the root dir in ZK for this cluster */
190   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
191 
192   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
193 
194   /**
195    * Parameter name for the limit on concurrent client-side zookeeper
196    * connections
197    */
198   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
199       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
200 
201   /** Parameter name for the ZK data directory */
202   public static final String ZOOKEEPER_DATA_DIR =
203       ZK_CFG_PROPERTY_PREFIX + "dataDir";
204 
205   /** Parameter name for the ZK tick time */
206   public static final String ZOOKEEPER_TICK_TIME =
207       ZK_CFG_PROPERTY_PREFIX + "tickTime";
208 
209   /** Default limit on concurrent client-side zookeeper connections */
210   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
211 
212   /** Configuration key for ZooKeeper session timeout */
213   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
214 
215   /** Default value for ZooKeeper session timeout */
216   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
217 
218   /** Configuration key for whether to use ZK.multi */
219   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
220 
221   /** Parameter name for port region server listens on. */
222   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
223 
224   /** Default port region server listens on. */
225   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
226 
227   /** default port for region server web api */
228   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
229 
230   /** A configuration key for regionserver info port */
231   public static final String REGIONSERVER_INFO_PORT =
232     "hbase.regionserver.info.port";
233 
234   /** A flag that enables automatic selection of regionserver info port */
235   public static final String REGIONSERVER_INFO_PORT_AUTO =
236       REGIONSERVER_INFO_PORT + ".auto";
237 
238   /** Parameter name for what region server implementation to use. */
239   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
240 
241   /** Parameter name for what master implementation to use. */
242   public static final String MASTER_IMPL= "hbase.master.impl";
243 
244   /** Parameter name for what hbase client implementation to use. */
245   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
246 
247   /** Parameter name for how often threads should wake up */
248   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
249 
250   /** Default value for thread wake frequency */
251   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
252 
253   /** Parameter name for how often we should try to write a version file, before failing */
254   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
255 
256   /** Parameter name for how often we should try to write a version file, before failing */
257   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
258 
259   /** Parameter name for how often a region should should perform a major compaction */
260   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
261 
262   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
263   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
264   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
265 
266   /** Parameter name for HBase instance root directory */
267   public static final String HBASE_DIR = "hbase.rootdir";
268 
269   /** Parameter name for HBase client IPC pool type */
270   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
271 
272   /** Parameter name for HBase client IPC pool size */
273   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
274 
275   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
276   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
277 
278   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
279   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
280     "hbase.client.meta.operation.timeout";
281 
282   /** Default HBase client operation timeout, which is tantamount to a blocking call */
283   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = Integer.MAX_VALUE;
284 
285   /** Used to construct the name of the log directory for a region server */
286   public static final String HREGION_LOGDIR_NAME = "WALs";
287 
288   /** Used to construct the name of the splitlog directory for a region server */
289   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
290 
291   /** Like the previous, but for old logs that are about to be deleted */
292   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
293 
294   public static final String CORRUPT_DIR_NAME = "corrupt";
295 
296   /** Used by HBCK to sideline backup data */
297   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
298 
299   /** Any artifacts left from migration can be moved here */
300   public static final String MIGRATION_NAME = ".migration";
301 
302   /**
303    * The directory from which co-processor/custom filter jars can be loaded
304    * dynamically by the region servers. This value can be overridden by the
305    * hbase.dynamic.jars.dir config.
306    */
307   public static final String LIB_DIR = "lib";
308 
309   /** Used to construct the name of the compaction directory during compaction */
310   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
311 
312   /** Conf key for the max file size after which we split the region */
313   public static final String HREGION_MAX_FILESIZE =
314       "hbase.hregion.max.filesize";
315 
316   /** Default maximum file size */
317   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
318 
319   /**
320    * Max size of single row for Get's or Scan's without in-row scanning flag set.
321    */
322   public static final String TABLE_MAX_ROWSIZE_KEY = "hbase.table.max.rowsize";
323 
324   /**
325    * Default max row size (1 Gb).
326    */
327   public static final long TABLE_MAX_ROWSIZE_DEFAULT = 1024 * 1024 * 1024L;
328 
329   /**
330    * The max number of threads used for opening and closing stores or store
331    * files in parallel
332    */
333   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
334     "hbase.hstore.open.and.close.threads.max";
335 
336   /**
337    * The default number for the max number of threads used for opening and
338    * closing stores or store files in parallel
339    */
340   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
341 
342 
343   /** Conf key for the memstore size at which we flush the memstore */
344   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
345       "hbase.hregion.memstore.flush.size";
346 
347   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
348       "hbase.hregion.edits.replay.skip.errors";
349 
350   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
351       false;
352 
353   /** Maximum value length, enforced on KeyValue construction */
354   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
355 
356   /** name of the file for unique cluster ID */
357   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
358 
359   /** Default value for cluster ID */
360   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
361 
362   /** Parameter name for # days to keep MVCC values during a major compaction */
363   public static final String KEEP_SEQID_PERIOD = "hbase.hstore.compaction.keep.seqId.period";
364   /** At least to keep MVCC values in hfiles for 5 days */
365   public static final int MIN_KEEP_SEQID_PERIOD = 5;
366 
367   // Always store the location of the root table's HRegion.
368   // This HRegion is never split.
369 
370   // region name = table + startkey + regionid. This is the row key.
371   // each row in the root and meta tables describes exactly 1 region
372   // Do we ever need to know all the information that we are storing?
373 
374   // Note that the name of the root table starts with "-" and the name of the
375   // meta table starts with "." Why? it's a trick. It turns out that when we
376   // store region names in memory, we use a SortedMap. Since "-" sorts before
377   // "." (and since no other table name can start with either of these
378   // characters, the root region will always be the first entry in such a Map,
379   // followed by all the meta regions (which will be ordered by their starting
380   // row key as well), followed by all user tables. So when the Master is
381   // choosing regions to assign, it will always choose the root region first,
382   // followed by the meta regions, followed by user regions. Since the root
383   // and meta regions always need to be on-line, this ensures that they will
384   // be the first to be reassigned if the server(s) they are being served by
385   // should go down.
386 
387 
388   /** The hbase:meta table's name. */
389   @Deprecated  // for compat from 0.94 -> 0.96.
390   public static final byte[] META_TABLE_NAME = TableName.META_TABLE_NAME.getName();
391 
392   public static final String BASE_NAMESPACE_DIR = "data";
393 
394   /** delimiter used between portions of a region name */
395   public static final int META_ROW_DELIMITER = ',';
396 
397   /** The catalog family as a string*/
398   public static final String CATALOG_FAMILY_STR = "info";
399 
400   /** The catalog family */
401   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
402 
403   /** The RegionInfo qualifier as a string */
404   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
405 
406   /** The regioninfo column qualifier */
407   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
408 
409   /** The server column qualifier */
410   public static final String SERVER_QUALIFIER_STR = "server";
411   /** The server column qualifier */
412   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes(SERVER_QUALIFIER_STR);
413 
414   /** The startcode column qualifier */
415   public static final String STARTCODE_QUALIFIER_STR = "serverstartcode";
416   /** The startcode column qualifier */
417   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes(STARTCODE_QUALIFIER_STR);
418 
419   /** The open seqnum column qualifier */
420   public static final String SEQNUM_QUALIFIER_STR = "seqnumDuringOpen";
421   /** The open seqnum column qualifier */
422   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes(SEQNUM_QUALIFIER_STR);
423 
424   /** The state column qualifier */
425   public static final String STATE_QUALIFIER_STR = "state";
426 
427   public static final byte [] STATE_QUALIFIER = Bytes.toBytes(STATE_QUALIFIER_STR);
428 
429   /**
430    * The serverName column qualifier. Its the server where the region is
431    * transitioning on, while column server is the server where the region is
432    * opened on. They are the same when the region is in state OPEN.
433    */
434   public static final String SERVERNAME_QUALIFIER_STR = "sn";
435 
436   public static final byte [] SERVERNAME_QUALIFIER = Bytes.toBytes(SERVERNAME_QUALIFIER_STR);
437 
438   /** The lower-half split region column qualifier */
439   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
440 
441   /** The upper-half split region column qualifier */
442   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
443 
444   /** The lower-half merge region column qualifier */
445   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
446 
447   /** The upper-half merge region column qualifier */
448   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
449 
450   /**
451    * The meta table version column qualifier.
452    * We keep current version of the meta table in this column in <code>-ROOT-</code>
453    * table: i.e. in the 'info:v' column.
454    */
455   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
456 
457   /**
458    * The current version of the meta table.
459    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
460    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
461    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
462    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
463    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
464    * byte[] serialization from Writables to Protobuf.
465    * See HRegionInfo.VERSION
466    */
467   public static final short META_VERSION = 1;
468 
469   // Other constants
470 
471   /**
472    * An empty instance.
473    */
474   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
475 
476   /**
477    * Used by scanners, etc when they want to start at the beginning of a region
478    */
479   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
480 
481   /**
482    * Last row in a table.
483    */
484   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
485 
486   /**
487     * Used by scanners and others when they're trying to detect the end of a
488     * table
489     */
490   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
491 
492   /**
493    * Max length a row can have because of the limitation in TFile.
494    */
495   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
496 
497   /**
498    * Timestamp to use when we want to refer to the latest cell.
499    * This is the timestamp sent by clients when no timestamp is specified on
500    * commit.
501    */
502   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
503 
504   /**
505    * Timestamp to use when we want to refer to the oldest cell.
506    */
507   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
508 
509   /**
510    * LATEST_TIMESTAMP in bytes form
511    */
512   public static final byte [] LATEST_TIMESTAMP_BYTES = {
513     // big-endian
514     (byte) (LATEST_TIMESTAMP >>> 56),
515     (byte) (LATEST_TIMESTAMP >>> 48),
516     (byte) (LATEST_TIMESTAMP >>> 40),
517     (byte) (LATEST_TIMESTAMP >>> 32),
518     (byte) (LATEST_TIMESTAMP >>> 24),
519     (byte) (LATEST_TIMESTAMP >>> 16),
520     (byte) (LATEST_TIMESTAMP >>> 8),
521     (byte) LATEST_TIMESTAMP,
522   };
523 
524   /**
525    * Define for 'return-all-versions'.
526    */
527   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
528 
529   /**
530    * Unlimited time-to-live.
531    */
532 //  public static final int FOREVER = -1;
533   public static final int FOREVER = Integer.MAX_VALUE;
534 
535   /**
536    * Seconds in a week
537    */
538   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
539 
540   /**
541    * Seconds in a day, hour and minute
542    */
543   public static final int DAY_IN_SECONDS = 24 * 60 * 60;
544   public static final int HOUR_IN_SECONDS = 60 * 60;
545   public static final int MINUTE_IN_SECONDS = 60;
546 
547   //TODO: although the following are referenced widely to format strings for
548   //      the shell. They really aren't a part of the public API. It would be
549   //      nice if we could put them somewhere where they did not need to be
550   //      public. They could have package visibility
551   public static final String NAME = "NAME";
552   public static final String VERSIONS = "VERSIONS";
553   public static final String IN_MEMORY = "IN_MEMORY";
554   public static final String METADATA = "METADATA";
555   public static final String CONFIGURATION = "CONFIGURATION";
556 
557   /**
558    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
559    * run out of array items.  Retries beyond this use the last number in the array.  So, for
560    * example, if hbase.client.pause is 1 second, and maximum retries count
561    * hbase.client.retries.number is 10, we will retry at the following intervals:
562    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
563    * With 100ms, a back-off of 200 means 20s
564    */
565   public static final int RETRY_BACKOFF[] = {1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200};
566 
567   public static final String REGION_IMPL = "hbase.hregion.impl";
568 
569   /** modifyTable op for replacing the table descriptor */
570   @InterfaceAudience.Private
571   public static enum Modify {
572     CLOSE_REGION,
573     TABLE_COMPACT,
574     TABLE_FLUSH,
575     TABLE_MAJOR_COMPACT,
576     TABLE_SET_HTD,
577     TABLE_SPLIT
578   }
579 
580   /**
581    * Scope tag for locally scoped data.
582    * This data will not be replicated.
583    */
584   public static final int REPLICATION_SCOPE_LOCAL = 0;
585 
586   /**
587    * Scope tag for globally scoped data.
588    * This data will be replicated to all peers.
589    */
590   public static final int REPLICATION_SCOPE_GLOBAL = 1;
591 
592   /**
593    * Default cluster ID, cannot be used to identify a cluster so a key with
594    * this value means it wasn't meant for replication.
595    */
596   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
597 
598     /**
599      * Parameter name for maximum number of bytes returned when calling a
600      * scanner's next method.
601      */
602   public static final String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY =
603       "hbase.client.scanner.max.result.size";
604 
605   /**
606    * Parameter name for maximum number of bytes returned when calling a scanner's next method.
607    * Controlled by the server.
608    */
609   public static final String HBASE_SERVER_SCANNER_MAX_RESULT_SIZE_KEY =
610       "hbase.server.scanner.max.result.size";
611 
612   /**
613    * Maximum number of bytes returned when calling a scanner's next method.
614    * Note that when a single row is larger than this limit the row is still
615    * returned completely.
616    *
617    * The default value is 2MB.
618    */
619   public static final long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = 2 * 1024 * 1024;
620 
621   /**
622    * Maximum number of bytes returned when calling a scanner's next method.
623    * Note that when a single row is larger than this limit the row is still
624    * returned completely.
625    * Safety setting to protect the region server.
626    *
627    * The default value unlimited for backwards compatibility
628    */
629   public static final long DEFAULT_HBASE_SERVER_SCANNER_MAX_RESULT_SIZE = Long.MAX_VALUE;
630 
631   /**
632    * Parameter name for client pause value, used mostly as value to wait
633    * before running a retry of a failed get, region lookup, etc.
634    */
635   public static final String HBASE_CLIENT_PAUSE = "hbase.client.pause";
636 
637   /**
638    * Default value of {@link #HBASE_CLIENT_PAUSE}.
639    */
640   public static final long DEFAULT_HBASE_CLIENT_PAUSE = 100;
641 
642   /**
643    * The maximum number of concurrent connections the client will maintain.
644    */
645   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
646 
647   /**
648    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
649    */
650   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
651 
652   /**
653    * The maximum number of concurrent connections the client will maintain to a single
654    * RegionServer.
655    */
656   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
657 
658   /**
659    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
660    */
661   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
662 
663   /**
664    * The maximum number of concurrent connections the client will maintain to a single
665    * Region.
666    */
667   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
668 
669   /**
670    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
671    */
672   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
673 
674   /**
675    * Parameter name for server pause value, used mostly as value to wait before
676    * running a retry of a failed operation.
677    */
678   public static final String HBASE_SERVER_PAUSE = "hbase.server.pause";
679 
680   /**
681    * Default value of {@link #HBASE_SERVER_PAUSE}.
682    */
683   public static final int DEFAULT_HBASE_SERVER_PAUSE = 1000;
684 
685   /**
686    * Parameter name for maximum retries, used as maximum for all retryable
687    * operations such as fetching of the root region from root region server,
688    * getting a cell's value, starting a row update, etc.
689    */
690   public static final String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
691 
692   /**
693    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
694    */
695   public static final int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
696 
697   /**
698    * Parameter name to set the default scanner caching for all clients.
699    */
700   public static final String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
701 
702   /**
703    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
704    */
705   public static final int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = 100;
706 
707   /**
708    * Parameter name for number of versions, kept by meta table.
709    */
710   public static String HBASE_META_VERSIONS = "hbase.meta.versions";
711 
712   /**
713    * Default value of {@link #HBASE_META_VERSIONS}.
714    */
715   public static int DEFAULT_HBASE_META_VERSIONS = 10;
716 
717   /**
718    * Parameter name for number of versions, kept by meta table.
719    */
720   public static String HBASE_META_BLOCK_SIZE = "hbase.meta.blocksize";
721 
722   /**
723    * Default value of {@link #HBASE_META_BLOCK_SIZE}.
724    */
725   public static int DEFAULT_HBASE_META_BLOCK_SIZE = 8 * 1024;
726 
727   /**
728    * Parameter name for number of rows that will be fetched when calling next on
729    * a scanner if it is not served from memory. Higher caching values will
730    * enable faster scanners but will eat up more memory and some calls of next
731    * may take longer and longer times when the cache is empty.
732    */
733   public static final String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
734 
735   /**
736    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
737    */
738   public static final int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
739 
740   /**
741    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
742    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
743    * for all intents and purposes, are the same except for their instance ids, then they will not be
744    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
745    * even if the instance ids are the same, it could result in non-shared
746    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
747    * differ.
748    */
749   public static final String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
750 
751   /**
752    * The client scanner timeout period in milliseconds.
753    */
754   public static final String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
755 
756   /**
757    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
758    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
759    */
760   @Deprecated
761   public static final String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
762       "hbase.regionserver.lease.period";
763 
764   /**
765    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
766    */
767   public static final int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
768 
769   /**
770    * timeout for each RPC
771    */
772   public static final String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
773 
774   /**
775    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
776    */
777   public static final int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
778 
779   /**
780    * timeout for short operation RPC
781    */
782   public static final String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY = "hbase.rpc.shortoperation.timeout";
783 
784   /**
785    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
786    */
787   public static final int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
788 
789   /**
790    * Value indicating the server name was saved with no sequence number.
791    */
792   public static final long NO_SEQNUM = -1;
793 
794 
795   /*
796    * cluster replication constants.
797    */
798   public static final String
799       REPLICATION_ENABLE_KEY = "hbase.replication";
800   public static final boolean
801       REPLICATION_ENABLE_DEFAULT = true;
802   public static final String
803       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
804   public static final String
805       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
806   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
807     "org.apache.hadoop.hbase.replication.regionserver.Replication";
808 
809   /** HBCK special code name used as server name when manipulating ZK nodes */
810   public static final String HBCK_CODE_NAME = "HBCKServerName";
811 
812   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
813     "hbase.regionserver.hostname.seen.by.master";
814 
815   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
816       "hbase.master.logcleaner.plugins";
817 
818   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
819     "hbase.regionserver.region.split.policy";
820 
821   /** Whether nonces are enabled; default is true. */
822   public static final String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
823 
824   /**
825    * Configuration key for the size of the block cache
826    */
827   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
828     "hfile.block.cache.size";
829 
830   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
831 
832   /*
833     * Minimum percentage of free heap necessary for a successful cluster startup.
834     */
835   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
836 
837   public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile
838       ("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
839   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
840       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
841 
842   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
843   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
844   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
845       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
846       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
847 
848   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
849   public static final int SOCKET_RETRY_WAIT_MS = 200;
850 
851   /** Host name of the local machine */
852   public static final String LOCALHOST = "localhost";
853 
854   /**
855    * If this parameter is set to true, then hbase will read
856    * data and then verify checksums. Checksum verification
857    * inside hdfs will be switched off.  However, if the hbase-checksum
858    * verification fails, then it will switch back to using
859    * hdfs checksums for verifiying data that is being read from storage.
860    *
861    * If this parameter is set to false, then hbase will not
862    * verify any checksums, instead it will depend on checksum verification
863    * being done in the hdfs client.
864    */
865   public static final String HBASE_CHECKSUM_VERIFICATION =
866       "hbase.regionserver.checksum.verify";
867 
868   public static final String LOCALHOST_IP = "127.0.0.1";
869 
870   /** Conf key that enables unflushed WAL edits directly being replayed to region servers */
871   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
872   /**
873    * Default 'distributed log replay' as true since hbase 1.1 (HBASE-12577)
874    */
875   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = false;
876   public static final String DISALLOW_WRITES_IN_RECOVERING =
877       "hbase.regionserver.disallow.writes.when.recovering";
878   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
879 
880   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
881   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
882 
883   /*
884    * REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT:
885    * -1  => Disable aborting
886    * 0   => Abort if even a single handler has died
887    * 0.x => Abort only when this percent of handlers have died
888    * 1   => Abort only all of the handers have died
889    */
890   public static final String REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT =
891 		  "hbase.regionserver.handler.abort.on.error.percent";
892   public static final double DEFAULT_REGION_SERVER_HANDLER_ABORT_ON_ERROR_PERCENT = 0.5;
893 
894   //High priority handlers to deal with admin requests and system table operation requests
895   public static final String REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT =
896       "hbase.regionserver.metahandler.count";
897   public static final int DEFAULT_REGION_SERVER_HIGH_PRIORITY_HANDLER_COUNT = 10;
898 
899   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
900       "hbase.regionserver.replication.handler.count";
901   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
902 
903   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
904   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
905 
906   /** Conf key that specifies timeout value to wait for a region ready */
907   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
908       "hbase.master.log.replay.wait.region.timeout";
909 
910   /**
911    * The name of the configuration parameter that specifies
912    * the number of bytes in a newly created checksum chunk.
913    */
914   public static final String BYTES_PER_CHECKSUM =
915       "hbase.hstore.bytes.per.checksum";
916 
917   /**
918    * The name of the configuration parameter that specifies
919    * the name of an algorithm that is used to compute checksums
920    * for newly created blocks.
921    */
922   public static final String CHECKSUM_TYPE_NAME =
923       "hbase.hstore.checksum.algorithm";
924 
925   /** Enable file permission modification from standard hbase */
926   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
927   /** File permission umask to use when creating hbase data files */
928   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
929 
930   /** Configuration name of WAL Compression */
931   public static final String ENABLE_WAL_COMPRESSION =
932     "hbase.regionserver.wal.enablecompression";
933 
934   /** Region in Transition metrics threshold time */
935   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
936 
937   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
938 
939   /**
940    * The byte array represents for NO_NEXT_INDEXED_KEY;
941    * The actual value is irrelevant because this is always compared by reference.
942    */
943   public static final Cell NO_NEXT_INDEXED_KEY = new KeyValue();
944   /** delimiter used between portions of a region name */
945   public static final int DELIMITER = ',';
946   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
947       "hbase.config.read.zookeeper.config";
948   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
949       false;
950 
951   /**
952    * QOS attributes: these attributes are used to demarcate RPC call processing
953    * by different set of handlers. For example, HIGH_QOS tagged methods are
954    * handled by high priority handlers.
955    */
956   public static final int NORMAL_QOS = 0;
957   public static final int QOS_THRESHOLD = 10;
958   public static final int HIGH_QOS = 200;
959   public static final int REPLICATION_QOS = 5; // normal_QOS < replication_QOS < high_QOS
960   public static final int REPLAY_QOS = 6; // REPLICATION_QOS < REPLAY_QOS < high_QOS
961   public static final int ADMIN_QOS = 100; // QOS_THRESHOLD < ADMIN_QOS < high_QOS
962   public static final int SYSTEMTABLE_QOS = HIGH_QOS;
963 
964   /** Directory under /hbase where archived hfiles are stored */
965   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
966 
967   /**
968    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
969    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
970    * uni-directional.
971    */
972   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
973 
974   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
975   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
976 
977   /** Temporary directory used for table creation and deletion */
978   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
979   /**
980    * The period (in milliseconds) between computing region server point in time metrics
981    */
982   public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
983   public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
984   /** Directories that are not HBase table directories */
985   public static final List<String> HBASE_NON_TABLE_DIRS =
986     Collections.unmodifiableList(Arrays.asList(new String[] {
987       HBCK_SIDELINEDIR_NAME, HBASE_TEMP_DIRECTORY, MIGRATION_NAME
988     }));
989 
990   /** Directories that are not HBase user table directories */
991   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
992     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
993       new String[] { TableName.META_TABLE_NAME.getNameAsString() },
994       HBASE_NON_TABLE_DIRS.toArray())));
995 
996   /** Health script related settings. */
997   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
998   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
999   public static final String HEALTH_CHORE_WAKE_FREQ =
1000       "hbase.node.health.script.frequency";
1001   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
1002   /**
1003    * The maximum number of health check failures a server can encounter consecutively.
1004    */
1005   public static final String HEALTH_FAILURE_THRESHOLD =
1006       "hbase.node.health.failure.threshold";
1007   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
1008 
1009 
1010   /**
1011    * Setting to activate, or not, the publication of the status by the master. Default
1012    *  notification is by a multicast message.
1013    */
1014   public static final String STATUS_PUBLISHED = "hbase.status.published";
1015   public static final boolean STATUS_PUBLISHED_DEFAULT = false;
1016 
1017   /**
1018    * IP to use for the multicast status messages between the master and the clients.
1019    * The default address is chosen as one among others within the ones suitable for multicast
1020    * messages.
1021    */
1022   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
1023   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
1024 
1025   /**
1026    * The address to use for binding the local socket for receiving multicast. Defaults to
1027    * 0.0.0.0.
1028    * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
1029    */
1030   public static final String STATUS_MULTICAST_BIND_ADDRESS = "hbase.status.multicast.bind.address.ip";
1031   public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
1032 
1033   /**
1034    * The port to use for the multicast messages.
1035    */
1036   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
1037   public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
1038 
1039   public static final long NO_NONCE = 0;
1040 
1041   /** Default cipher for encryption */
1042   public static final String CIPHER_AES = "AES";
1043 
1044   /** Configuration key for the crypto algorithm provider, a class name */
1045   public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
1046 
1047   /** Configuration key for the crypto key provider, a class name */
1048   public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
1049 
1050   /** Configuration key for the crypto key provider parameters */
1051   public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
1052       "hbase.crypto.keyprovider.parameters";
1053 
1054   /** Configuration key for the name of the master key for the cluster, a string */
1055   public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
1056 
1057   /** Configuration key for the name of the alternate master key for the cluster, a string */
1058   public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
1059     "hbase.crypto.master.alternate.key.name";
1060 
1061   /** Configuration key for the algorithm to use when encrypting the WAL, a string */
1062   public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
1063 
1064   /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
1065   public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
1066 
1067   /** Configuration key for the algorithm used for creating jks key, a string */
1068   public static final String CRYPTO_KEY_ALGORITHM_CONF_KEY = "hbase.crypto.key.algorithm";
1069 
1070   /** Configuration key for the name of the alternate cipher algorithm for the cluster, a string */
1071   public static final String CRYPTO_ALTERNATE_KEY_ALGORITHM_CONF_KEY =
1072       "hbase.crypto.alternate.key.algorithm";
1073 
1074   /** Configuration key for enabling WAL encryption, a boolean */
1075   public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
1076 
1077   /** Configuration key for setting RPC codec class name */
1078   public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
1079 
1080   /** Configuration key for setting replication codec class name */
1081   public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
1082 
1083   /** Config for pluggable consensus provider */
1084   public static final String HBASE_COORDINATED_STATE_MANAGER_CLASS =
1085     "hbase.coordinated.state.manager.class";
1086 
1087   /** Configuration key for SplitLog manager timeout */
1088   public static final String HBASE_SPLITLOG_MANAGER_TIMEOUT = "hbase.splitlog.manager.timeout";
1089 
1090   /**
1091    * Configuration keys for Bucket cache
1092    */
1093   // TODO moving these bucket cache implementation specific configs to this level is violation of
1094   // encapsulation. But as these has to be referred from hbase-common and bucket cache
1095   // sits in hbase-server, there were no other go! Can we move the cache implementation to
1096   // hbase-common?
1097 
1098   /**
1099    * Current ioengine options in include: heap, offheap and file:PATH (where PATH is the path
1100    * to the file that will host the file-based cache.  See BucketCache#getIOEngineFromName() for
1101    * list of supported ioengine options.
1102    * <p>Set this option and a non-zero {@link #BUCKET_CACHE_SIZE_KEY} to enable bucket cache.
1103    */
1104   public static final String BUCKET_CACHE_IOENGINE_KEY = "hbase.bucketcache.ioengine";
1105 
1106   /**
1107    * When using bucket cache, this is a float that EITHER represents a percentage of total heap
1108    * memory size to give to the cache (if < 1.0) OR, it is the capacity in megabytes of the cache.
1109    */
1110   public static final String BUCKET_CACHE_SIZE_KEY = "hbase.bucketcache.size";
1111 
1112   /**
1113    * HConstants for fast fail on the client side follow
1114    */
1115   /**
1116    * Config for enabling/disabling the fast fail mode.
1117    */
1118   public static final String HBASE_CLIENT_FAST_FAIL_MODE_ENABLED =
1119       "hbase.client.fast.fail.mode.enabled";
1120 
1121   public static final boolean HBASE_CLIENT_ENABLE_FAST_FAIL_MODE_DEFAULT =
1122       false;
1123 
1124   public static final String HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS =
1125       "hbase.client.fastfail.threshold";
1126 
1127   public static final long HBASE_CLIENT_FAST_FAIL_THREASHOLD_MS_DEFAULT =
1128       60000;
1129 
1130   public static final String HBASE_CLIENT_FAST_FAIL_CLEANUP_MS_DURATION_MS =
1131       "hbase.client.fast.fail.cleanup.duration";
1132 
1133   public static final long HBASE_CLIENT_FAST_FAIL_CLEANUP_DURATION_MS_DEFAULT =
1134       600000;
1135 
1136   public static final String HBASE_CLIENT_FAST_FAIL_INTERCEPTOR_IMPL =
1137       "hbase.client.fast.fail.interceptor.impl";
1138 
1139   /** Config key for if the server should send backpressure and if the client should listen to
1140    * that backpressure from the server */
1141   public static final String ENABLE_CLIENT_BACKPRESSURE = "hbase.client.backpressure.enabled";
1142   public static final boolean DEFAULT_ENABLE_CLIENT_BACKPRESSURE = false;
1143 
1144   public static final String HEAP_OCCUPANCY_LOW_WATERMARK_KEY =
1145       "hbase.heap.occupancy.low_water_mark";
1146   public static final float DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK = 0.95f;
1147   public static final String HEAP_OCCUPANCY_HIGH_WATERMARK_KEY =
1148       "hbase.heap.occupancy.high_water_mark";
1149   public static final float DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK = 0.98f;
1150 
1151   private HConstants() {
1152     // Can't be instantiated with this ctor.
1153   }
1154 }