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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.classification.InterfaceAudience;
32  import org.apache.hadoop.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    public enum OperationStatusCode {
88      NOT_RUN,
89      SUCCESS,
90      BAD_FAMILY,
91      SANITY_CHECK_FAILURE,
92      FAILURE;
93    }
94  
95    /** long constant for zero */
96    public static final Long ZERO_L = Long.valueOf(0L);
97    public static final String NINES = "99999999999999";
98    public static final String ZEROES = "00000000000000";
99  
100   // For migration
101 
102   /** name of version file */
103   public static final String VERSION_FILE_NAME = "hbase.version";
104 
105   /**
106    * Current version of file system.
107    * Version 4 supports only one kind of bloom filter.
108    * Version 5 changes versions in catalog table regions.
109    * Version 6 enables blockcaching on catalog tables.
110    * Version 7 introduces hfile -- hbase 0.19 to 0.20..
111    * Version 8 introduces namespace
112    */
113   // public static final String FILE_SYSTEM_VERSION = "6";
114   public static final String FILE_SYSTEM_VERSION = "8";
115 
116   // Configuration parameters
117 
118   //TODO: Is having HBase homed on port 60k OK?
119 
120   /** Cluster is in distributed mode or not */
121   public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";
122 
123   /** Config for pluggable load balancers */
124   public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";
125 
126   /** Cluster is standalone or pseudo-distributed */
127   public static final boolean CLUSTER_IS_LOCAL = false;
128 
129   /** Cluster is fully-distributed */
130   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
131 
132   /** Default value for cluster distributed mode */
133   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
134 
135   /** default host address */
136   public static final String DEFAULT_HOST = "0.0.0.0";
137 
138   /** Parameter name for port master listens on. */
139   public static final String MASTER_PORT = "hbase.master.port";
140 
141   /** default port that the master listens on */
142   public static final int DEFAULT_MASTER_PORT = 16000;
143 
144   /** default port for master web api */
145   public static final int DEFAULT_MASTER_INFOPORT = 16010;
146 
147   /** Configuration key for master web API port */
148   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
149 
150   /** Parameter name for the master type being backup (waits for primary to go inactive). */
151   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
152 
153   /** by default every master is a possible primary master unless the conf explicitly overrides it */
154   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
155 
156   /** Name of ZooKeeper quorum configuration parameter. */
157   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
158 
159   /** Name of ZooKeeper config file in conf/ directory. */
160   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
161 
162   /** Common prefix of ZooKeeper configuration properties */
163   public static final String ZK_CFG_PROPERTY_PREFIX =
164       "hbase.zookeeper.property.";
165 
166   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
167       ZK_CFG_PROPERTY_PREFIX.length();
168 
169   /**
170    * The ZK client port key in the ZK properties map. The name reflects the
171    * fact that this is not an HBase configuration key.
172    */
173   public static final String CLIENT_PORT_STR = "clientPort";
174 
175   /** Parameter name for the client port that the zookeeper listens on */
176   public static final String ZOOKEEPER_CLIENT_PORT =
177       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
178 
179   /** Default client port that the zookeeper listens on */
180   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
181 
182   /** Parameter name for the wait time for the recoverable zookeeper */
183   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";
184 
185   /** Default wait time for the recoverable zookeeper */
186   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
187 
188   /** Parameter name for the root dir in ZK for this cluster */
189   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
190 
191   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
192 
193   /**
194    * Parameter name for the limit on concurrent client-side zookeeper
195    * connections
196    */
197   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
198       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
199 
200   /** Parameter name for the ZK data directory */
201   public static final String ZOOKEEPER_DATA_DIR =
202       ZK_CFG_PROPERTY_PREFIX + "dataDir";
203 
204   /** Default limit on concurrent client-side zookeeper connections */
205   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
206 
207   /** Configuration key for ZooKeeper session timeout */
208   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
209 
210   /** Default value for ZooKeeper session timeout */
211   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
212 
213   /** Configuration key for whether to use ZK.multi */
214   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
215 
216   /** Parameter name for port region server listens on. */
217   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
218 
219   /** Default port region server listens on. */
220   public static final int DEFAULT_REGIONSERVER_PORT = 16020;
221 
222   /** default port for region server web api */
223   public static final int DEFAULT_REGIONSERVER_INFOPORT = 16030;
224 
225   /** A configuration key for regionserver info port */
226   public static final String REGIONSERVER_INFO_PORT =
227     "hbase.regionserver.info.port";
228 
229   /** A flag that enables automatic selection of regionserver info port */
230   public static final String REGIONSERVER_INFO_PORT_AUTO =
231       REGIONSERVER_INFO_PORT + ".auto";
232 
233   /** Parameter name for what region server implementation to use. */
234   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
235 
236   /** Parameter name for what master implementation to use. */
237   public static final String MASTER_IMPL= "hbase.master.impl";
238 
239   /** Parameter name for what hbase client implementation to use. */
240   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
241 
242   /** Parameter name for how often threads should wake up */
243   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
244 
245   /** Default value for thread wake frequency */
246   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
247 
248   /** Parameter name for how often we should try to write a version file, before failing */
249   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
250 
251   /** Parameter name for how often we should try to write a version file, before failing */
252   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
253 
254   /** Parameter name for how often a region should should perform a major compaction */
255   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
256 
257   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
258   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
259   public static final int COMPACTION_KV_MAX_DEFAULT = 10;
260 
261   /** Parameter name for HBase instance root directory */
262   public static final String HBASE_DIR = "hbase.rootdir";
263 
264   /** Parameter name for HBase client IPC pool type */
265   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
266 
267   /** Parameter name for HBase client IPC pool size */
268   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
269 
270   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
271   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
272 
273   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
274   public static final String HBASE_CLIENT_META_OPERATION_TIMEOUT =
275     "hbase.client.meta.operation.timeout";
276 
277   /** Default HBase client operation timeout, which is tantamount to a blocking call */
278   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = Integer.MAX_VALUE;
279 
280   /** Used to construct the name of the log directory for a region server */
281   public static final String HREGION_LOGDIR_NAME = "WALs";
282 
283   /** Used to construct the name of the splitlog directory for a region server */
284   public static final String SPLIT_LOGDIR_NAME = "splitWAL";
285 
286   /** Like the previous, but for old logs that are about to be deleted */
287   public static final String HREGION_OLDLOGDIR_NAME = "oldWALs";
288 
289   public static final String CORRUPT_DIR_NAME = "corrupt";
290 
291   /** Used by HBCK to sideline backup data */
292   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
293 
294   /** Any artifacts left from migration can be moved here */
295   public static final String MIGRATION_NAME = ".migration";
296 
297   /**
298    * The directory from which co-processor/custom filter jars can be loaded
299    * dynamically by the region servers. This value can be overridden by the
300    * hbase.dynamic.jars.dir config.
301    */
302   public static final String LIB_DIR = "lib";
303 
304   /** Used to construct the name of the compaction directory during compaction */
305   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
306 
307   /** Conf key for the max file size after which we split the region */
308   public static final String HREGION_MAX_FILESIZE =
309       "hbase.hregion.max.filesize";
310 
311   /** Default maximum file size */
312   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
313 
314   /**
315    * The max number of threads used for opening and closing stores or store
316    * files in parallel
317    */
318   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
319     "hbase.hstore.open.and.close.threads.max";
320 
321   /**
322    * The default number for the max number of threads used for opening and
323    * closing stores or store files in parallel
324    */
325   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
326 
327 
328   /** Conf key for the memstore size at which we flush the memstore */
329   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
330       "hbase.hregion.memstore.flush.size";
331 
332   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
333       "hbase.hregion.edits.replay.skip.errors";
334 
335   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
336       false;
337 
338   /** Maximum value length, enforced on KeyValue construction */
339   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
340 
341   /** name of the file for unique cluster ID */
342   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
343 
344   /** Default value for cluster ID */
345   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
346 
347   // Always store the location of the root table's HRegion.
348   // This HRegion is never split.
349 
350   // region name = table + startkey + regionid. This is the row key.
351   // each row in the root and meta tables describes exactly 1 region
352   // Do we ever need to know all the information that we are storing?
353 
354   // Note that the name of the root table starts with "-" and the name of the
355   // meta table starts with "." Why? it's a trick. It turns out that when we
356   // store region names in memory, we use a SortedMap. Since "-" sorts before
357   // "." (and since no other table name can start with either of these
358   // characters, the root region will always be the first entry in such a Map,
359   // followed by all the meta regions (which will be ordered by their starting
360   // row key as well), followed by all user tables. So when the Master is
361   // choosing regions to assign, it will always choose the root region first,
362   // followed by the meta regions, followed by user regions. Since the root
363   // and meta regions always need to be on-line, this ensures that they will
364   // be the first to be reassigned if the server(s) they are being served by
365   // should go down.
366 
367 
368   /** The hbase:meta table's name. */
369   @Deprecated  // for compat from 0.94 -> 0.96.
370   public static final byte[] META_TABLE_NAME = TableName.META_TABLE_NAME.getName();
371 
372   public static final String BASE_NAMESPACE_DIR = "data";
373 
374   /** delimiter used between portions of a region name */
375   public static final int META_ROW_DELIMITER = ',';
376 
377   /** The catalog family as a string*/
378   public static final String CATALOG_FAMILY_STR = "info";
379 
380   /** The catalog family */
381   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
382 
383   /** The RegionInfo qualifier as a string */
384   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
385 
386   /** The regioninfo column qualifier */
387   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
388 
389   /** The server column qualifier */
390   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes("server");
391 
392   /** The startcode column qualifier */
393   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes("serverstartcode");
394 
395   /** The open seqnum column qualifier */
396   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes("seqnumDuringOpen");
397 
398   /** The lower-half split region column qualifier */
399   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
400 
401   /** The upper-half split region column qualifier */
402   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
403 
404   /** The lower-half merge region column qualifier */
405   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
406 
407   /** The upper-half merge region column qualifier */
408   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
409 
410   /**
411    * The meta table version column qualifier.
412    * We keep current version of the meta table in this column in <code>-ROOT-</code>
413    * table: i.e. in the 'info:v' column.
414    */
415   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
416 
417   /**
418    * The current version of the meta table.
419    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
420    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
421    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
422    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
423    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
424    * byte[] serialization from Writables to Protobuf.
425    * See HRegionInfo.VERSION
426    */
427   public static final short META_VERSION = 1;
428 
429   // Other constants
430 
431   /**
432    * An empty instance.
433    */
434   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
435 
436   /**
437    * Used by scanners, etc when they want to start at the beginning of a region
438    */
439   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
440 
441   /**
442    * Last row in a table.
443    */
444   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
445 
446   /**
447     * Used by scanners and others when they're trying to detect the end of a
448     * table
449     */
450   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
451 
452   /**
453    * Max length a row can have because of the limitation in TFile.
454    */
455   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
456 
457   /**
458    * Timestamp to use when we want to refer to the latest cell.
459    * This is the timestamp sent by clients when no timestamp is specified on
460    * commit.
461    */
462   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
463 
464   /**
465    * Timestamp to use when we want to refer to the oldest cell.
466    */
467   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
468 
469   /**
470    * LATEST_TIMESTAMP in bytes form
471    */
472   public static final byte [] LATEST_TIMESTAMP_BYTES = {
473     // big-endian
474     (byte) (LATEST_TIMESTAMP >>> 56),
475     (byte) (LATEST_TIMESTAMP >>> 48),
476     (byte) (LATEST_TIMESTAMP >>> 40),
477     (byte) (LATEST_TIMESTAMP >>> 32),
478     (byte) (LATEST_TIMESTAMP >>> 24),
479     (byte) (LATEST_TIMESTAMP >>> 16),
480     (byte) (LATEST_TIMESTAMP >>> 8),
481     (byte) LATEST_TIMESTAMP,
482   };
483 
484   /**
485    * Define for 'return-all-versions'.
486    */
487   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
488 
489   /**
490    * Unlimited time-to-live.
491    */
492 //  public static final int FOREVER = -1;
493   public static final int FOREVER = Integer.MAX_VALUE;
494 
495   /**
496    * Seconds in a week
497    */
498   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
499 
500   //TODO: although the following are referenced widely to format strings for
501   //      the shell. They really aren't a part of the public API. It would be
502   //      nice if we could put them somewhere where they did not need to be
503   //      public. They could have package visibility
504   public static final String NAME = "NAME";
505   public static final String VERSIONS = "VERSIONS";
506   public static final String IN_MEMORY = "IN_MEMORY";
507   public static final String METADATA = "METADATA";
508   public static final String CONFIGURATION = "CONFIGURATION";
509 
510   /**
511    * Retrying we multiply hbase.client.pause setting by what we have in this array until we
512    * run out of array items.  Retries beyond this use the last number in the array.  So, for
513    * example, if hbase.client.pause is 1 second, and maximum retries count
514    * hbase.client.retries.number is 10, we will retry at the following intervals:
515    * 1, 2, 3, 5, 10, 20, 40, 100, 100, 100.
516    * With 100ms, a back-off of 200 means 20s
517    */
518   public static int RETRY_BACKOFF[] = { 1, 2, 3, 5, 10, 20, 40, 100, 100, 100, 100, 200, 200 };
519 
520   public static final String REGION_IMPL = "hbase.hregion.impl";
521 
522   /** modifyTable op for replacing the table descriptor */
523   public static enum Modify {
524     CLOSE_REGION,
525     TABLE_COMPACT,
526     TABLE_FLUSH,
527     TABLE_MAJOR_COMPACT,
528     TABLE_SET_HTD,
529     TABLE_SPLIT
530   }
531 
532   /**
533    * Scope tag for locally scoped data.
534    * This data will not be replicated.
535    */
536   public static final int REPLICATION_SCOPE_LOCAL = 0;
537 
538   /**
539    * Scope tag for globally scoped data.
540    * This data will be replicated to all peers.
541    */
542   public static final int REPLICATION_SCOPE_GLOBAL = 1;
543 
544   /**
545    * Default cluster ID, cannot be used to identify a cluster so a key with
546    * this value means it wasn't meant for replication.
547    */
548   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
549 
550     /**
551      * Parameter name for maximum number of bytes returned when calling a
552      * scanner's next method.
553      */
554   public static String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY = "hbase.client.scanner.max.result.size";
555 
556   /**
557    * Maximum number of bytes returned when calling a scanner's next method.
558    * Note that when a single row is larger than this limit the row is still
559    * returned completely.
560    *
561    * The default value is unlimited.
562    */
563   public static long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = Long.MAX_VALUE;
564 
565   /**
566    * Parameter name for client pause value, used mostly as value to wait
567    * before running a retry of a failed get, region lookup, etc.
568    */
569   public static String HBASE_CLIENT_PAUSE = "hbase.client.pause";
570 
571   /**
572    * Default value of {@link #HBASE_CLIENT_PAUSE}.
573    */
574   public static long DEFAULT_HBASE_CLIENT_PAUSE = 100;
575 
576   /**
577    * The maximum number of concurrent connections the client will maintain.
578    */
579   public static final String HBASE_CLIENT_MAX_TOTAL_TASKS = "hbase.client.max.total.tasks";
580 
581   /**
582    * Default value of {@link #HBASE_CLIENT_MAX_TOTAL_TASKS}.
583    */
584   public static final int DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS = 100;
585 
586   /**
587    * The maximum number of concurrent connections the client will maintain to a single
588    * RegionServer.
589    */
590   public static final String HBASE_CLIENT_MAX_PERSERVER_TASKS = "hbase.client.max.perserver.tasks";
591 
592   /**
593    * Default value of {@link #HBASE_CLIENT_MAX_PERSERVER_TASKS}.
594    */
595   public static final int DEFAULT_HBASE_CLIENT_MAX_PERSERVER_TASKS = 2;
596 
597   /**
598    * The maximum number of concurrent connections the client will maintain to a single
599    * Region.
600    */
601   public static final String HBASE_CLIENT_MAX_PERREGION_TASKS = "hbase.client.max.perregion.tasks";
602 
603   /**
604    * Default value of {@link #HBASE_CLIENT_MAX_PERREGION_TASKS}.
605    */
606   public static final int DEFAULT_HBASE_CLIENT_MAX_PERREGION_TASKS = 1;
607 
608   /**
609    * Parameter name for server pause value, used mostly as value to wait before
610    * running a retry of a failed operation.
611    */
612   public static String HBASE_SERVER_PAUSE = "hbase.server.pause";
613 
614   /**
615    * Default value of {@link #HBASE_SERVER_PAUSE}.
616    */
617   public static int DEFAULT_HBASE_SERVER_PAUSE = 1000;
618 
619   /**
620    * Parameter name for maximum retries, used as maximum for all retryable
621    * operations such as fetching of the root region from root region server,
622    * getting a cell's value, starting a row update, etc.
623    */
624   public static String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
625 
626   /**
627    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
628    */
629   public static int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 31;
630 
631   /**
632    * Parameter name for client prefetch limit, used as the maximum number of regions
633    * info that will be prefetched.
634    */
635   public static String HBASE_CLIENT_PREFETCH_LIMIT = "hbase.client.prefetch.limit";
636 
637   /**
638    * Default value of {@link #HBASE_CLIENT_PREFETCH_LIMIT}.
639    */
640   public static int DEFAULT_HBASE_CLIENT_PREFETCH_LIMIT = 10;
641 
642   /**
643    * Parameter name to set the default scanner caching for all clients.
644    */
645   public static String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
646 
647   /**
648    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
649    */
650   public static int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = 100;
651 
652   /**
653    * Parameter name for number of rows that will be fetched when calling next on
654    * a scanner if it is not served from memory. Higher caching values will
655    * enable faster scanners but will eat up more memory and some calls of next
656    * may take longer and longer times when the cache is empty.
657    */
658   public static String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
659 
660   /**
661    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
662    */
663   public static int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
664 
665   /**
666    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
667    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
668    * for all intents and purposes, are the same except for their instance ids, then they will not be
669    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
670    * even if the instance ids are the same, it could result in non-shared
671    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
672    * differ.
673    */
674   public static String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
675 
676   /**
677    * The client scanner timeout period in milliseconds.
678    */
679   public static String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
680 
681   /**
682    * Use {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD} instead.
683    * @deprecated This config option is deprecated. Will be removed at later releases after 0.96.
684    */
685   @Deprecated
686   public static String HBASE_REGIONSERVER_LEASE_PERIOD_KEY =
687       "hbase.regionserver.lease.period";
688 
689   /**
690    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
691    */
692   public static int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
693 
694   /**
695    * timeout for each RPC
696    */
697   public static String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
698 
699   /**
700    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
701    */
702   public static int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
703 
704   /**
705    * timeout for short operation RPC
706    */
707   public static String HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY = "hbase.rpc.shortoperation.timeout";
708 
709   /**
710    * Default value of {@link #HBASE_RPC_SHORTOPERATION_TIMEOUT_KEY}
711    */
712   public static int DEFAULT_HBASE_RPC_SHORTOPERATION_TIMEOUT = 10000;
713 
714   /**
715    * Value indicating the server name was saved with no sequence number.
716    */
717   public static final long NO_SEQNUM = -1;
718 
719 
720   /*
721    * cluster replication constants.
722    */
723   public static final String
724       REPLICATION_ENABLE_KEY = "hbase.replication";
725   public static final boolean
726       REPLICATION_ENABLE_DEFAULT = true;
727   public static final String
728       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
729   public static final String
730       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
731   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
732     "org.apache.hadoop.hbase.replication.regionserver.Replication";
733 
734   /** HBCK special code name used as server name when manipulating ZK nodes */
735   public static final String HBCK_CODE_NAME = "HBCKServerName";
736 
737   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
738     "hbase.regionserver.hostname.seen.by.master";
739 
740   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
741       "hbase.master.logcleaner.plugins";
742 
743   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
744     "hbase.regionserver.region.split.policy";
745 
746   /** Whether nonces are enabled; default is true. */
747   public static String HBASE_RS_NONCES_ENABLED = "hbase.regionserver.nonces.enabled";
748 
749   /**
750    * Configuration key for the size of the block cache
751    */
752   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
753     "hfile.block.cache.size";
754 
755   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.4f;
756 
757   /*
758     * Minimum percentage of free heap necessary for a successful cluster startup.
759     */
760   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
761 
762   public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile
763       ("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
764   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
765       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
766 
767   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
768   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
769   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
770       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
771       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
772 
773   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
774   public static final int SOCKET_RETRY_WAIT_MS = 200;
775 
776   /** Host name of the local machine */
777   public static final String LOCALHOST = "localhost";
778 
779   /**
780    * If this parameter is set to true, then hbase will read
781    * data and then verify checksums. Checksum verification
782    * inside hdfs will be switched off.  However, if the hbase-checksum
783    * verification fails, then it will switch back to using
784    * hdfs checksums for verifiying data that is being read from storage.
785    *
786    * If this parameter is set to false, then hbase will not
787    * verify any checksums, instead it will depend on checksum verification
788    * being done in the hdfs client.
789    */
790   public static final String HBASE_CHECKSUM_VERIFICATION =
791       "hbase.regionserver.checksum.verify";
792 
793   public static final String LOCALHOST_IP = "127.0.0.1";
794 
795   /** Conf key that enables unflushed WAL edits directly being replayed to region servers */
796   public static final String DISTRIBUTED_LOG_REPLAY_KEY = "hbase.master.distributed.log.replay";
797   public static final boolean DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG = false;
798   public static final String DISALLOW_WRITES_IN_RECOVERING =
799       "hbase.regionserver.disallow.writes.when.recovering";
800   public static final boolean DEFAULT_DISALLOW_WRITES_IN_RECOVERING_CONFIG = false;
801 
802   public static final String REGION_SERVER_HANDLER_COUNT = "hbase.regionserver.handler.count";
803   public static final int DEFAULT_REGION_SERVER_HANDLER_COUNT = 30;
804 
805   public static final String REGION_SERVER_META_HANDLER_COUNT =
806       "hbase.regionserver.metahandler.count";
807   public static final int DEFAULT_REGION_SERVER_META_HANDLER_COUNT = 10;
808 
809   public static final String REGION_SERVER_REPLICATION_HANDLER_COUNT =
810       "hbase.regionserver.replication.handler.count";
811   public static final int DEFAULT_REGION_SERVER_REPLICATION_HANDLER_COUNT = 3;
812 
813   public static final String MASTER_HANDLER_COUNT = "hbase.master.handler.count";
814   public static final int DEFAULT_MASTER_HANLDER_COUNT = 25;
815 
816   /** Conf key that specifies timeout value to wait for a region ready */
817   public static final String LOG_REPLAY_WAIT_REGION_TIMEOUT =
818       "hbase.master.log.replay.wait.region.timeout";
819 
820   /**
821    * The name of the configuration parameter that specifies
822    * the number of bytes in a newly created checksum chunk.
823    */
824   public static final String BYTES_PER_CHECKSUM =
825       "hbase.hstore.bytes.per.checksum";
826 
827   /**
828    * The name of the configuration parameter that specifies
829    * the name of an algorithm that is used to compute checksums
830    * for newly created blocks.
831    */
832   public static final String CHECKSUM_TYPE_NAME =
833       "hbase.hstore.checksum.algorithm";
834 
835   /** Enable file permission modification from standard hbase */
836   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
837   /** File permission umask to use when creating hbase data files */
838   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
839 
840   /** Configuration name of HLog Compression */
841   public static final String ENABLE_WAL_COMPRESSION =
842     "hbase.regionserver.wal.enablecompression";
843 
844   /** Region in Transition metrics threshold time */
845   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
846 
847   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
848 
849   /**
850    * The byte array represents for NO_NEXT_INDEXED_KEY;
851    * The actual value is irrelevant because this is always compared by reference.
852    */
853   public static final byte [] NO_NEXT_INDEXED_KEY = Bytes.toBytes("NO_NEXT_INDEXED_KEY");
854   /** delimiter used between portions of a region name */
855   public static final int DELIMITER = ',';
856   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
857       "hbase.config.read.zookeeper.config";
858   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
859       false;
860 
861   /**
862    * QOS attributes: these attributes are used to demarcate RPC call processing
863    * by different set of handlers. For example, HIGH_QOS tagged methods are
864    * handled by high priority handlers.
865    */
866   public static final int NORMAL_QOS = 0;
867   public static final int QOS_THRESHOLD = 10;
868   public static final int HIGH_QOS = 100;
869   public static final int REPLICATION_QOS = 5; // normal_QOS < replication_QOS < high_QOS
870   public static final int REPLAY_QOS = 6; // REPLICATION_QOS < REPLAY_QOS < high_QOS
871 
872   /** Directory under /hbase where archived hfiles are stored */
873   public static final String HFILE_ARCHIVE_DIRECTORY = "archive";
874 
875   /**
876    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
877    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
878    * uni-directional.
879    */
880   public static final String SNAPSHOT_DIR_NAME = ".hbase-snapshot";
881 
882   /* Name of old snapshot directory. See HBASE-8352 for details on why it needs to be renamed */
883   public static final String OLD_SNAPSHOT_DIR_NAME = ".snapshot";
884 
885   /** Temporary directory used for table creation and deletion */
886   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
887   /**
888    * The period (in milliseconds) between computing region server point in time metrics
889    */
890   public static final String REGIONSERVER_METRICS_PERIOD = "hbase.regionserver.metrics.period";
891   public static final long DEFAULT_REGIONSERVER_METRICS_PERIOD = 5000;
892   /** Directories that are not HBase table directories */
893   public static final List<String> HBASE_NON_TABLE_DIRS =
894     Collections.unmodifiableList(Arrays.asList(new String[] { HREGION_LOGDIR_NAME,
895       HREGION_OLDLOGDIR_NAME, CORRUPT_DIR_NAME, SPLIT_LOGDIR_NAME,
896       HBCK_SIDELINEDIR_NAME, HFILE_ARCHIVE_DIRECTORY, SNAPSHOT_DIR_NAME, HBASE_TEMP_DIRECTORY,
897       OLD_SNAPSHOT_DIR_NAME, BASE_NAMESPACE_DIR, MIGRATION_NAME, LIB_DIR}));
898 
899   /** Directories that are not HBase user table directories */
900   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
901     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
902       new String[] { TableName.META_TABLE_NAME.getNameAsString() },
903       HBASE_NON_TABLE_DIRS.toArray())));
904 
905   /** Health script related settings. */
906   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
907   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
908   public static final String HEALTH_CHORE_WAKE_FREQ =
909       "hbase.node.health.script.frequency";
910   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
911   /**
912    * The maximum number of health check failures a server can encounter consecutively.
913    */
914   public static final String HEALTH_FAILURE_THRESHOLD =
915       "hbase.node.health.failure.threshold";
916   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
917 
918 
919   /**
920    * Setting to activate, or not, the publication of the status by the master. Default
921    *  notification is by a multicast message.
922    */
923   public static final String STATUS_PUBLISHED = "hbase.status.published";
924   public static final boolean STATUS_PUBLISHED_DEFAULT = false;
925 
926   /**
927    * IP to use for the multicast status messages between the master and the clients.
928    * The default address is chosen as one among others within the ones suitable for multicast
929    * messages.
930    */
931   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
932   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
933 
934   /**
935    * The address to use for binding the local socket for receiving multicast. Defaults to
936    * 0.0.0.0.
937    * @see <a href="https://issues.apache.org/jira/browse/HBASE-9961">HBASE-9961</a>
938    */
939   public static final String STATUS_MULTICAST_BIND_ADDRESS = "hbase.status.multicast.bind.address.ip";
940   public static final String DEFAULT_STATUS_MULTICAST_BIND_ADDRESS = "0.0.0.0";
941 
942   /**
943    * The port to use for the multicast messages.
944    */
945   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.address.port";
946   public static final int DEFAULT_STATUS_MULTICAST_PORT = 16100;
947 
948   public static final long NO_NONCE = 0;
949 
950   /** Configuration key for the crypto algorithm provider, a class name */
951   public static final String CRYPTO_CIPHERPROVIDER_CONF_KEY = "hbase.crypto.cipherprovider";
952 
953   /** Configuration key for the crypto key provider, a class name */
954   public static final String CRYPTO_KEYPROVIDER_CONF_KEY = "hbase.crypto.keyprovider";
955 
956   /** Configuration key for the crypto key provider parameters */
957   public static final String CRYPTO_KEYPROVIDER_PARAMETERS_KEY =
958       "hbase.crypto.keyprovider.parameters";
959 
960   /** Configuration key for the name of the master key for the cluster, a string */
961   public static final String CRYPTO_MASTERKEY_NAME_CONF_KEY = "hbase.crypto.master.key.name";
962 
963   /** Configuration key for the name of the alternate master key for the cluster, a string */
964   public static final String CRYPTO_MASTERKEY_ALTERNATE_NAME_CONF_KEY =
965     "hbase.crypto.master.alternate.key.name";
966 
967   /** Configuration key for the algorithm to use when encrypting the WAL, a string */
968   public static final String CRYPTO_WAL_ALGORITHM_CONF_KEY = "hbase.crypto.wal.algorithm";
969 
970   /** Configuration key for the name of the master WAL encryption key for the cluster, a string */
971   public static final String CRYPTO_WAL_KEY_NAME_CONF_KEY = "hbase.crypto.wal.key.name";
972 
973   /** Configuration key for enabling HLog encryption, a boolean */
974   public static final String ENABLE_WAL_ENCRYPTION = "hbase.regionserver.wal.encryption";
975 
976   /** Configuration key for setting RPC codec class name */
977   public static final String RPC_CODEC_CONF_KEY = "hbase.client.rpc.codec";
978 
979   /** Configuration key for setting replication codec class name */
980   public static final String REPLICATION_CODEC_CONF_KEY = "hbase.replication.rpc.codec";
981 
982   private HConstants() {
983     // Can't be instantiated with this ctor.
984   }
985 }