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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    /** When we encode strings, we always specify UTF8 encoding */
42    public static final String UTF8_ENCODING = "UTF-8";
43  
44    /** When we encode strings, we always specify UTF8 encoding */
45    public static final Charset UTF8_CHARSET = Charset.forName(UTF8_ENCODING);
46    /**
47     * Default block size for an HFile.
48     */
49    public final static int DEFAULT_BLOCKSIZE = 64 * 1024;
50  
51    /** Used as a magic return value while optimized index key feature enabled(HBASE-7845) */
52    public final static int INDEX_KEY_MAGIC = -2;
53    /*
54       * Name of directory that holds recovered edits written by the wal log
55       * splitting code, one per region
56       */
57    public static final String RECOVERED_EDITS_DIR = "recovered.edits";
58    /**
59     * The first four bytes of Hadoop RPC connections
60     */
61    public static final ByteBuffer RPC_HEADER = ByteBuffer.wrap("HBas".getBytes());
62    public static final byte RPC_CURRENT_VERSION = 0;
63  
64    // HFileBlock constants.
65  
66    /** The size data structures with minor version is 0 */
67    public static final int HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM = MAGIC_LENGTH + 2 * Bytes.SIZEOF_INT
68        + Bytes.SIZEOF_LONG;
69    /** The size of a version 2 HFile block header, minor version 1.
70     * There is a 1 byte checksum type, followed by a 4 byte bytesPerChecksum
71     * followed by another 4 byte value to store sizeofDataOnDisk.
72     */
73    public static final int HFILEBLOCK_HEADER_SIZE = HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM +
74      Bytes.SIZEOF_BYTE + 2 * Bytes.SIZEOF_INT;
75    /** Just an array of bytes of the right size. */
76    public static final byte[] HFILEBLOCK_DUMMY_HEADER = new byte[HFILEBLOCK_HEADER_SIZE];
77  
78    //End HFileBlockConstants.
79  
80    /**
81     * Status codes used for return values of bulk operations.
82     */
83    public enum OperationStatusCode {
84      NOT_RUN,
85      SUCCESS,
86      BAD_FAMILY,
87      SANITY_CHECK_FAILURE,
88      FAILURE;
89    }
90  
91    /** long constant for zero */
92    public static final Long ZERO_L = Long.valueOf(0L);
93    public static final String NINES = "99999999999999";
94    public static final String ZEROES = "00000000000000";
95  
96    // For migration
97  
98    /** name of version file */
99    public static final String VERSION_FILE_NAME = "hbase.version";
100 
101   /**
102    * Current version of file system.
103    * Version 4 supports only one kind of bloom filter.
104    * Version 5 changes versions in catalog table regions.
105    * Version 6 enables blockcaching on catalog tables.
106    * Version 7 introduces hfile -- hbase 0.19 to 0.20..
107    */
108   // public static final String FILE_SYSTEM_VERSION = "6";
109   public static final String FILE_SYSTEM_VERSION = "7";
110 
111   // Configuration parameters
112 
113   //TODO: Is having HBase homed on port 60k OK?
114 
115   /** Cluster is in distributed mode or not */
116   public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";
117 
118   /** Config for pluggable load balancers */
119   public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";
120 
121   /** Cluster is standalone or pseudo-distributed */
122   public static final boolean CLUSTER_IS_LOCAL = false;
123 
124   /** Cluster is fully-distributed */
125   public static final boolean CLUSTER_IS_DISTRIBUTED = true;
126 
127   /** Default value for cluster distributed mode */
128   public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;
129 
130   /** default host address */
131   public static final String DEFAULT_HOST = "0.0.0.0";
132 
133   /** Parameter name for port master listens on. */
134   public static final String MASTER_PORT = "hbase.master.port";
135 
136   /** default port that the master listens on */
137   public static final int DEFAULT_MASTER_PORT = 60000;
138 
139   /** default port for master web api */
140   public static final int DEFAULT_MASTER_INFOPORT = 60010;
141 
142   /** Configuration key for master web API port */
143   public static final String MASTER_INFO_PORT = "hbase.master.info.port";
144 
145   /** Parameter name for the master type being backup (waits for primary to go inactive). */
146   public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";
147 
148   /** by default every master is a possible primary master unless the conf explicitly overrides it */
149   public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;
150 
151   /** Name of ZooKeeper quorum configuration parameter. */
152   public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";
153 
154   /** Name of ZooKeeper config file in conf/ directory. */
155   public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";
156 
157   /** Common prefix of ZooKeeper configuration properties */
158   public static final String ZK_CFG_PROPERTY_PREFIX =
159       "hbase.zookeeper.property.";
160 
161   public static final int ZK_CFG_PROPERTY_PREFIX_LEN =
162       ZK_CFG_PROPERTY_PREFIX.length();
163 
164   /**
165    * The ZK client port key in the ZK properties map. The name reflects the
166    * fact that this is not an HBase configuration key.
167    */
168   public static final String CLIENT_PORT_STR = "clientPort";
169 
170   /** Parameter name for the client port that the zookeeper listens on */
171   public static final String ZOOKEEPER_CLIENT_PORT =
172       ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;
173 
174   /** Default client port that the zookeeper listens on */
175   public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;
176 
177   /** Parameter name for the wait time for the recoverable zookeeper */
178   public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";
179 
180   /** Default wait time for the recoverable zookeeper */
181   public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;
182 
183   /** Parameter name for the root dir in ZK for this cluster */
184   public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";
185 
186   public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";
187 
188   /**
189    * Parameter name for the limit on concurrent client-side zookeeper
190    * connections
191    */
192   public static final String ZOOKEEPER_MAX_CLIENT_CNXNS =
193       ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";
194 
195   /** Parameter name for the ZK data directory */
196   public static final String ZOOKEEPER_DATA_DIR =
197       ZK_CFG_PROPERTY_PREFIX + "dataDir";
198 
199   /** Default limit on concurrent client-side zookeeper connections */
200   public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;
201 
202   /** Configuration key for ZooKeeper session timeout */
203   public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";
204 
205   /** Default value for ZooKeeper session timeout */
206   public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;
207 
208   /** Configuration key for whether to use ZK.multi */
209   public static final String ZOOKEEPER_USEMULTI = "hbase.zookeeper.useMulti";
210 
211   /** Parameter name for port region server listens on. */
212   public static final String REGIONSERVER_PORT = "hbase.regionserver.port";
213 
214   /** Default port region server listens on. */
215   public static final int DEFAULT_REGIONSERVER_PORT = 60020;
216 
217   /** default port for region server web api */
218   public static final int DEFAULT_REGIONSERVER_INFOPORT = 60030;
219 
220   /** A configuration key for regionserver info port */
221   public static final String REGIONSERVER_INFO_PORT =
222     "hbase.regionserver.info.port";
223 
224   /** A flag that enables automatic selection of regionserver info port */
225   public static final String REGIONSERVER_INFO_PORT_AUTO =
226       REGIONSERVER_INFO_PORT + ".auto";
227 
228   /** Parameter name for what region server implementation to use. */
229   public static final String REGION_SERVER_IMPL= "hbase.regionserver.impl";
230 
231   /** Parameter name for what master implementation to use. */
232   public static final String MASTER_IMPL= "hbase.master.impl";
233 
234   /** Parameter name for what hbase client implementation to use. */
235   public static final String HBASECLIENT_IMPL= "hbase.hbaseclient.impl";
236 
237   /** Parameter name for how often threads should wake up */
238   public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";
239 
240   /** Default value for thread wake frequency */
241   public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;
242 
243   /** Parameter name for how often we should try to write a version file, before failing */
244   public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";
245 
246   /** Parameter name for how often we should try to write a version file, before failing */
247   public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;
248 
249   /** Parameter name for how often a region should should perform a major compaction */
250   public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";
251 
252   /** Parameter name for the maximum batch of KVs to be used in flushes and compactions */
253   public static final String COMPACTION_KV_MAX = "hbase.hstore.compaction.kv.max";
254 
255   /** Parameter name for HBase instance root directory */
256   public static final String HBASE_DIR = "hbase.rootdir";
257 
258   /** Parameter name for HBase client IPC pool type */
259   public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";
260 
261   /** Parameter name for HBase client IPC pool size */
262   public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";
263 
264   /** Parameter name for HBase client operation timeout, which overrides RPC timeout */
265   public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";
266 
267   /** Default HBase client operation timeout, which is tantamount to a blocking call */
268   public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = Integer.MAX_VALUE;
269 
270   /** Used to construct the name of the log directory for a region server
271    * Use '.' as a special character to seperate the log files from table data */
272   public static final String HREGION_LOGDIR_NAME = ".logs";
273 
274   /** Used to construct the name of the splitlog directory for a region server */
275   public static final String SPLIT_LOGDIR_NAME = "splitlog";
276 
277   public static final String CORRUPT_DIR_NAME = ".corrupt";
278 
279   /** Like the previous, but for old logs that are about to be deleted */
280   public static final String HREGION_OLDLOGDIR_NAME = ".oldlogs";
281 
282   /** Used by HBCK to sideline backup data */
283   public static final String HBCK_SIDELINEDIR_NAME = ".hbck";
284 
285   /** Used to construct the name of the compaction directory during compaction */
286   public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";
287 
288   /** Conf key for the max file size after which we split the region */
289   public static final String HREGION_MAX_FILESIZE =
290       "hbase.hregion.max.filesize";
291 
292   /** Default maximum file size */
293   public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;
294 
295   /**
296    * The max number of threads used for opening and closing stores or store
297    * files in parallel
298    */
299   public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX =
300     "hbase.hstore.open.and.close.threads.max";
301 
302   /**
303    * The default number for the max number of threads used for opening and
304    * closing stores or store files in parallel
305    */
306   public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;
307 
308 
309   /** Conf key for the memstore size at which we flush the memstore */
310   public static final String HREGION_MEMSTORE_FLUSH_SIZE =
311       "hbase.hregion.memstore.flush.size";
312 
313   public static final String HREGION_EDITS_REPLAY_SKIP_ERRORS =
314       "hbase.hregion.edits.replay.skip.errors";
315 
316   public static final boolean DEFAULT_HREGION_EDITS_REPLAY_SKIP_ERRORS =
317       false;
318 
319   /** Maximum value length, enforced on KeyValue construction */
320   public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE - 1;
321 
322   /** name of the file for unique cluster ID */
323   public static final String CLUSTER_ID_FILE_NAME = "hbase.id";
324 
325   /** Default value for cluster ID */
326   public static final String CLUSTER_ID_DEFAULT = "default-cluster";
327 
328   // Always store the location of the root table's HRegion.
329   // This HRegion is never split.
330 
331   // region name = table + startkey + regionid. This is the row key.
332   // each row in the root and meta tables describes exactly 1 region
333   // Do we ever need to know all the information that we are storing?
334 
335   // Note that the name of the root table starts with "-" and the name of the
336   // meta table starts with "." Why? it's a trick. It turns out that when we
337   // store region names in memory, we use a SortedMap. Since "-" sorts before
338   // "." (and since no other table name can start with either of these
339   // characters, the root region will always be the first entry in such a Map,
340   // followed by all the meta regions (which will be ordered by their starting
341   // row key as well), followed by all user tables. So when the Master is
342   // choosing regions to assign, it will always choose the root region first,
343   // followed by the meta regions, followed by user regions. Since the root
344   // and meta regions always need to be on-line, this ensures that they will
345   // be the first to be reassigned if the server(s) they are being served by
346   // should go down.
347 
348   /** The root table's name.*/
349   public static final byte [] ROOT_TABLE_NAME = Bytes.toBytes("-ROOT-");
350 
351   /** The META table's name. */
352   public static final byte [] META_TABLE_NAME = Bytes.toBytes(".META.");
353 
354   /** delimiter used between portions of a region name */
355   public static final int META_ROW_DELIMITER = ',';
356 
357   /** The catalog family as a string*/
358   public static final String CATALOG_FAMILY_STR = "info";
359 
360   /** The catalog family */
361   public static final byte [] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);
362 
363   /** The RegionInfo qualifier as a string */
364   public static final String REGIONINFO_QUALIFIER_STR = "regioninfo";
365 
366   /** The regioninfo column qualifier */
367   public static final byte [] REGIONINFO_QUALIFIER = Bytes.toBytes(REGIONINFO_QUALIFIER_STR);
368 
369   /** The server column qualifier */
370   public static final byte [] SERVER_QUALIFIER = Bytes.toBytes("server");
371 
372   /** The startcode column qualifier */
373   public static final byte [] STARTCODE_QUALIFIER = Bytes.toBytes("serverstartcode");
374 
375   /** The open seqnum column qualifier */
376   public static final byte [] SEQNUM_QUALIFIER = Bytes.toBytes("seqnumDuringOpen");
377 
378   /** The lower-half split region column qualifier */
379   public static final byte [] SPLITA_QUALIFIER = Bytes.toBytes("splitA");
380 
381   /** The upper-half split region column qualifier */
382   public static final byte [] SPLITB_QUALIFIER = Bytes.toBytes("splitB");
383 
384   /** The lower-half merge region column qualifier */
385   public static final byte[] MERGEA_QUALIFIER = Bytes.toBytes("mergeA");
386 
387   /** The upper-half merge region column qualifier */
388   public static final byte[] MERGEB_QUALIFIER = Bytes.toBytes("mergeB");
389 
390   /**
391    * The meta table version column qualifier.
392    * We keep current version of the meta table in this column in <code>-ROOT-</code>
393    * table: i.e. in the 'info:v' column.
394    */
395   public static final byte [] META_VERSION_QUALIFIER = Bytes.toBytes("v");
396 
397   /**
398    * The current version of the meta table.
399    * - pre-hbase 0.92.  There is no META_VERSION column in the root table
400    * in this case. The meta has HTableDescriptor serialized into the HRegionInfo;
401    * - version 0 is 0.92 and 0.94. Meta data has serialized HRegionInfo's using
402    * Writable serialization, and HRegionInfo's does not contain HTableDescriptors.
403    * - version 1 for 0.96+ keeps HRegionInfo data structures, but changes the
404    * byte[] serialization from Writables to Protobuf.
405    * See HRegionInfo.VERSION
406    */
407   public static final short META_VERSION = 1;
408 
409   // Other constants
410 
411   /**
412    * An empty instance.
413    */
414   public static final byte [] EMPTY_BYTE_ARRAY = new byte [0];
415 
416   /**
417    * Used by scanners, etc when they want to start at the beginning of a region
418    */
419   public static final byte [] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;
420 
421   /**
422    * Last row in a table.
423    */
424   public static final byte [] EMPTY_END_ROW = EMPTY_START_ROW;
425 
426   /**
427     * Used by scanners and others when they're trying to detect the end of a
428     * table
429     */
430   public static final byte [] LAST_ROW = EMPTY_BYTE_ARRAY;
431 
432   /**
433    * Max length a row can have because of the limitation in TFile.
434    */
435   public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;
436 
437   /**
438    * Timestamp to use when we want to refer to the latest cell.
439    * This is the timestamp sent by clients when no timestamp is specified on
440    * commit.
441    */
442   public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;
443 
444   /**
445    * Timestamp to use when we want to refer to the oldest cell.
446    */
447   public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;
448 
449   /**
450    * LATEST_TIMESTAMP in bytes form
451    */
452   public static final byte [] LATEST_TIMESTAMP_BYTES = {
453     // big-endian
454     (byte) (LATEST_TIMESTAMP >>> 56),
455     (byte) (LATEST_TIMESTAMP >>> 48),
456     (byte) (LATEST_TIMESTAMP >>> 40),
457     (byte) (LATEST_TIMESTAMP >>> 32),
458     (byte) (LATEST_TIMESTAMP >>> 24),
459     (byte) (LATEST_TIMESTAMP >>> 16),
460     (byte) (LATEST_TIMESTAMP >>> 8),
461     (byte) LATEST_TIMESTAMP,
462   };
463 
464   /**
465    * Define for 'return-all-versions'.
466    */
467   public static final int ALL_VERSIONS = Integer.MAX_VALUE;
468 
469   /**
470    * Unlimited time-to-live.
471    */
472 //  public static final int FOREVER = -1;
473   public static final int FOREVER = Integer.MAX_VALUE;
474 
475   /**
476    * Seconds in a week
477    */
478   public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;
479 
480   //TODO: although the following are referenced widely to format strings for
481   //      the shell. They really aren't a part of the public API. It would be
482   //      nice if we could put them somewhere where they did not need to be
483   //      public. They could have package visibility
484   public static final String NAME = "NAME";
485   public static final String VERSIONS = "VERSIONS";
486   public static final String IN_MEMORY = "IN_MEMORY";
487   public static final String METADATA = "METADATA";
488   public static final String CONFIGURATION = "CONFIGURATION";
489 
490   /**
491    * This is a retry backoff multiplier table similar to the BSD TCP syn
492    * backoff table, a bit more aggressive than simple exponential backoff.
493    */
494   public static int RETRY_BACKOFF[] = { 1, 1, 1, 2, 2, 4, 4, 8, 16, 32 };
495 
496   public static final String REGION_IMPL = "hbase.hregion.impl";
497 
498   /** modifyTable op for replacing the table descriptor */
499   public static enum Modify {
500     CLOSE_REGION,
501     TABLE_COMPACT,
502     TABLE_FLUSH,
503     TABLE_MAJOR_COMPACT,
504     TABLE_SET_HTD,
505     TABLE_SPLIT
506   }
507 
508   /**
509    * Scope tag for locally scoped data.
510    * This data will not be replicated.
511    */
512   public static final int REPLICATION_SCOPE_LOCAL = 0;
513 
514   /**
515    * Scope tag for globally scoped data.
516    * This data will be replicated to all peers.
517    */
518   public static final int REPLICATION_SCOPE_GLOBAL = 1;
519 
520   /**
521    * Default cluster ID, cannot be used to identify a cluster so a key with
522    * this value means it wasn't meant for replication.
523    */
524   public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L,0L);
525 
526     /**
527      * Parameter name for maximum number of bytes returned when calling a
528      * scanner's next method.
529      */
530   public static String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY = "hbase.client.scanner.max.result.size";
531 
532   /**
533    * Maximum number of bytes returned when calling a scanner's next method.
534    * Note that when a single row is larger than this limit the row is still
535    * returned completely.
536    *
537    * The default value is unlimited.
538    */
539   public static long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = Long.MAX_VALUE;
540 
541   /**
542    * Parameter name for client pause value, used mostly as value to wait
543    * before running a retry of a failed get, region lookup, etc.
544    */
545   public static String HBASE_CLIENT_PAUSE = "hbase.client.pause";
546 
547   /**
548    * Default value of {@link #HBASE_CLIENT_PAUSE}.
549    */
550   public static long DEFAULT_HBASE_CLIENT_PAUSE = 1000;
551 
552   /**
553    * Parameter name for server pause value, used mostly as value to wait before
554    * running a retry of a failed operation.
555    */
556   public static String HBASE_SERVER_PAUSE = "hbase.server.pause";
557 
558   /**
559    * Default value of {@link #HBASE_SERVER_PAUSE}.
560    */
561   public static int DEFAULT_HBASE_SERVER_PAUSE = 1000;
562 
563   /**
564    * Parameter name for maximum retries, used as maximum for all retryable
565    * operations such as fetching of the root region from root region server,
566    * getting a cell's value, starting a row update, etc.
567    */
568   public static String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";
569 
570   /**
571    * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
572    */
573   public static int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 10;
574 
575   /**
576    * Parameter name for maximum attempts, used to limit the number of times the
577    * client will try to obtain the proxy for a given region server.
578    */
579   public static String HBASE_CLIENT_RPC_MAXATTEMPTS = "hbase.client.rpc.maxattempts";
580 
581   /**
582    * Default value of {@link #HBASE_CLIENT_RPC_MAXATTEMPTS}.
583    */
584   public static int DEFAULT_HBASE_CLIENT_RPC_MAXATTEMPTS = 1;
585 
586   /**
587    * Parameter name for client prefetch limit, used as the maximum number of regions
588    * info that will be prefetched.
589    */
590   public static String HBASE_CLIENT_PREFETCH_LIMIT = "hbase.client.prefetch.limit";
591 
592   /**
593    * Default value of {@link #HBASE_CLIENT_PREFETCH_LIMIT}.
594    */
595   public static int DEFAULT_HBASE_CLIENT_PREFETCH_LIMIT = 10;
596 
597   /**
598    * Parameter name to set the default scanner caching for all clients.
599    */
600   public static String HBASE_CLIENT_SCANNER_CACHING = "hbase.client.scanner.caching";
601 
602   /**
603    * Default value for {@link #HBASE_CLIENT_SCANNER_CACHING}
604    */
605   public static int DEFAULT_HBASE_CLIENT_SCANNER_CACHING = 100;
606 
607   /**
608    * Parameter name for number of rows that will be fetched when calling next on
609    * a scanner if it is not served from memory. Higher caching values will
610    * enable faster scanners but will eat up more memory and some calls of next
611    * may take longer and longer times when the cache is empty.
612    */
613   public static String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";
614 
615   /**
616    * Default value of {@link #HBASE_META_SCANNER_CACHING}.
617    */
618   public static int DEFAULT_HBASE_META_SCANNER_CACHING = 100;
619 
620   /**
621    * Parameter name for unique identifier for this {@link org.apache.hadoop.conf.Configuration}
622    * instance. If there are two or more {@link org.apache.hadoop.conf.Configuration} instances that,
623    * for all intents and purposes, are the same except for their instance ids, then they will not be
624    * able to share the same org.apache.hadoop.hbase.client.HConnection instance. On the other hand,
625    * even if the instance ids are the same, it could result in non-shared
626    * org.apache.hadoop.hbase.client.HConnection instances if some of the other connection parameters
627    * differ.
628    */
629   public static String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";
630 
631   /**
632    * The client scanner timeout period in milliseconds.
633    */
634   public static String HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = "hbase.client.scanner.timeout.period";
635 
636   /**
637    * Default value of {@link #HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD}.
638    */
639   public static int DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD = 60000;
640 
641   /**
642    * timeout for each RPC
643    */
644   public static String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";
645 
646   /**
647    * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
648    */
649   public static int DEFAULT_HBASE_RPC_TIMEOUT = 60000;
650 
651   /**
652    * Value indicating the server name was saved with no sequence number.
653    */
654   public static final long NO_SEQNUM = -1;
655 
656 
657   /*
658    * cluster replication constants.
659    */
660   public static final String
661       REPLICATION_ENABLE_KEY = "hbase.replication";
662   public static final String
663       REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
664   public static final String
665       REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
666   public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT =
667     "org.apache.hadoop.hbase.replication.regionserver.Replication";
668 
669   /** HBCK special code name used as server name when manipulating ZK nodes */
670   public static final String HBCK_CODE_NAME = "HBCKServerName";
671 
672   public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER =
673     "hbase.regionserver.hostname.seen.by.master";
674 
675   public static final String HBASE_MASTER_LOGCLEANER_PLUGINS =
676       "hbase.master.logcleaner.plugins";
677 
678   public static final String HBASE_REGION_SPLIT_POLICY_KEY =
679     "hbase.regionserver.region.split.policy";
680 
681   /**
682    * Configuration key for the size of the block cache
683    */
684   public static final String HFILE_BLOCK_CACHE_SIZE_KEY =
685     "hfile.block.cache.size";
686 
687   public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.25f;
688 
689   /*
690     * Minimum percentage of free heap necessary for a successful cluster startup.
691     */
692   public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;
693 
694   public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile
695       ("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
696   public static final Pattern CP_HTD_ATTR_VALUE_PATTERN =
697       Pattern.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");
698 
699   public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
700   public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
701   public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile(
702       "(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN + ")=(" +
703       CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");
704 
705   /** The delay when re-trying a socket operation in a loop (HBASE-4712) */
706   public static final int SOCKET_RETRY_WAIT_MS = 200;
707 
708   /** Host name of the local machine */
709   public static final String LOCALHOST = "localhost";
710 
711   /**
712    * If this parameter is set to true, then hbase will read
713    * data and then verify checksums. Checksum verification
714    * inside hdfs will be switched off.  However, if the hbase-checksum
715    * verification fails, then it will switch back to using
716    * hdfs checksums for verifiying data that is being read from storage.
717    *
718    * If this parameter is set to false, then hbase will not
719    * verify any checksums, instead it will depend on checksum verification
720    * being done in the hdfs client.
721    */
722   public static final String HBASE_CHECKSUM_VERIFICATION =
723       "hbase.regionserver.checksum.verify";
724 
725   public static final String LOCALHOST_IP = "127.0.0.1";
726 
727   /** Conf key that enables distributed log splitting */
728   public static final String DISTRIBUTED_LOG_SPLITTING_KEY =
729       "hbase.master.distributed.log.splitting";
730 
731   /**
732    * The name of the configuration parameter that specifies
733    * the number of bytes in a newly created checksum chunk.
734    */
735   public static final String BYTES_PER_CHECKSUM =
736       "hbase.hstore.bytes.per.checksum";
737 
738   /**
739    * The name of the configuration parameter that specifies
740    * the name of an algorithm that is used to compute checksums
741    * for newly created blocks.
742    */
743   public static final String CHECKSUM_TYPE_NAME =
744       "hbase.hstore.checksum.algorithm";
745 
746   /** Enable file permission modification from standard hbase */
747   public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
748   /** File permission umask to use when creating hbase data files */
749   public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";
750 
751   /** Configuration name of HLog Compression */
752   public static final String ENABLE_WAL_COMPRESSION =
753     "hbase.regionserver.wal.enablecompression";
754 
755   /** Region in Transition metrics threshold time */
756   public static final String METRICS_RIT_STUCK_WARNING_THRESHOLD="hbase.metrics.rit.stuck.warning.threshold";
757 
758   public static final String LOAD_BALANCER_SLOP_KEY = "hbase.regions.slop";
759 
760   /**
761    * The byte array represents for NO_NEXT_INDEXED_KEY;
762    * The actual value is irrelevant because this is always compared by reference.
763    */
764   public static final byte [] NO_NEXT_INDEXED_KEY = Bytes.toBytes("NO_NEXT_INDEXED_KEY");
765   /** delimiter used between portions of a region name */
766   public static final int DELIMITER = ',';
767   public static final String HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
768       "hbase.config.read.zookeeper.config";
769   public static final boolean DEFAULT_HBASE_CONFIG_READ_ZOOKEEPER_CONFIG =
770       false;
771 
772   /**
773    * QOS attributes: these attributes are used to demarcate RPC call processing
774    * by different set of handlers. For example, HIGH_QOS tagged methods are
775    * handled by high priority handlers.
776    */
777   public static final int NORMAL_QOS = 0;
778   public static final int QOS_THRESHOLD = 10;
779   public static final int HIGH_QOS = 100;
780   public static final int REPLICATION_QOS = 5; // normal_QOS < replication_QOS < high_QOS
781 
782   /** Directory under /hbase where archived hfiles are stored */
783   public static final String HFILE_ARCHIVE_DIRECTORY = ".archive";
784 
785   /**
786    * Name of the directory to store all snapshots. See SnapshotDescriptionUtils for
787    * remaining snapshot constants; this is here to keep HConstants dependencies at a minimum and
788    * uni-directional.
789    */
790   public static final String SNAPSHOT_DIR_NAME = ".snapshot";
791 
792   /** Temporary directory used for table creation and deletion */
793   public static final String HBASE_TEMP_DIRECTORY = ".tmp";
794 
795   /** Directories that are not HBase table directories */
796   public static final List<String> HBASE_NON_TABLE_DIRS =
797     Collections.unmodifiableList(Arrays.asList(new String[] { HREGION_LOGDIR_NAME,
798       HREGION_OLDLOGDIR_NAME, CORRUPT_DIR_NAME, SPLIT_LOGDIR_NAME,
799       HBCK_SIDELINEDIR_NAME, HFILE_ARCHIVE_DIRECTORY, SNAPSHOT_DIR_NAME, HBASE_TEMP_DIRECTORY }));
800 
801   /** Directories that are not HBase user table directories */
802   public static final List<String> HBASE_NON_USER_TABLE_DIRS =
803     Collections.unmodifiableList(Arrays.asList((String[])ArrayUtils.addAll(
804       new String[] { Bytes.toString(META_TABLE_NAME), Bytes.toString(ROOT_TABLE_NAME) },
805       HBASE_NON_TABLE_DIRS.toArray())));
806 
807   /** Health script related settings. */
808   public static final String HEALTH_SCRIPT_LOC = "hbase.node.health.script.location";
809   public static final String HEALTH_SCRIPT_TIMEOUT = "hbase.node.health.script.timeout";
810   public static final String HEALTH_CHORE_WAKE_FREQ =
811       "hbase.node.health.script.frequency";
812   public static final long DEFAULT_HEALTH_SCRIPT_TIMEOUT = 60000;
813   /**
814    * The maximum number of health check failures a server can encounter consecutively.
815    */
816   public static final String HEALTH_FAILURE_THRESHOLD =
817       "hbase.node.health.failure.threshold";
818   public static final int DEFAULT_HEALTH_FAILURE_THRESHOLD = 3;
819 
820 
821   /**
822    * IP to use for the multicast status messages between the master and the clients.
823    * The default address is chosen as one among others within the ones suitable for multicast
824    * messages.
825    */
826   public static final String STATUS_MULTICAST_ADDRESS = "hbase.status.multicast.address.ip";
827   public static final String DEFAULT_STATUS_MULTICAST_ADDRESS = "226.1.1.3";
828 
829   /**
830    * The port to use for the multicast messages.
831    */
832   public static final String STATUS_MULTICAST_PORT = "hbase.status.multicast.port";
833   public static final int DEFAULT_STATUS_MULTICAST_PORT = 60100;
834 
835 
836 
837   private HConstants() {
838     // Can't be instantiated with this ctor.
839   }
840 }