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