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1   /**
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.client;
21  
22  import java.io.Closeable;
23  import java.io.IOException;
24  import java.util.List;
25  import java.util.Map;
26  import java.util.concurrent.ExecutorService;
27  
28  import org.apache.hadoop.conf.Configuration;
29  import org.apache.hadoop.hbase.Abortable;
30  import org.apache.hadoop.hbase.HRegionInfo;
31  import org.apache.hadoop.hbase.HRegionLocation;
32  import org.apache.hadoop.hbase.HServerAddress;
33  import org.apache.hadoop.hbase.HTableDescriptor;
34  import org.apache.hadoop.hbase.MasterNotRunningException;
35  import org.apache.hadoop.hbase.ZooKeeperConnectionException;
36  import org.apache.hadoop.hbase.catalog.CatalogTracker;
37  import org.apache.hadoop.hbase.client.coprocessor.Batch;
38  import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;
39  import org.apache.hadoop.hbase.ipc.HMasterInterface;
40  import org.apache.hadoop.hbase.ipc.HRegionInterface;
41  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
42  
43  /**
44   * Cluster connection.  Hosts a connection to the ZooKeeper ensemble and
45   * thereafter into the HBase cluster.  Knows how to locate regions out on the cluster,
46   * keeps a cache of locations and then knows how to recalibrate after they move.
47   * {@link HConnectionManager} manages instances of this class.
48   *
49   * <p>HConnections are used by {@link HTable} mostly but also by
50   * {@link HBaseAdmin}, {@link CatalogTracker},
51   * and {@link ZooKeeperWatcher}.  HConnection instances can be shared.  Sharing
52   * is usually what you want because rather than each HConnection instance
53   * having to do its own discovery of regions out on the cluster, instead, all
54   * clients get to share the one cache of locations.  Sharing makes cleanup of
55   * HConnections awkward.  See {@link HConnectionManager} for cleanup
56   * discussion.
57   *
58   * @see HConnectionManager
59   */
60  public interface HConnection extends Abortable, Closeable {
61    /**
62     * @return Configuration instance being used by this HConnection instance.
63     */
64    public Configuration getConfiguration();
65  
66    /**
67     * Retrieve ZooKeeperWatcher used by this connection.
68     * @return ZooKeeperWatcher handle being used by the connection.
69     * @throws IOException if a remote or network exception occurs
70     * @deprecated Removed because it was a mistake exposing zookeeper in this
71     * interface (ZooKeeper is an implementation detail).
72     * Deprecated in HBase 0.94
73     */
74    @Deprecated
75    public ZooKeeperWatcher getZooKeeperWatcher() throws IOException;
76  
77    /**
78     * @return proxy connection to master server for this instance
79     * @throws MasterNotRunningException if the master is not running
80     * @throws ZooKeeperConnectionException if unable to connect to zookeeper
81     * @deprecated Removed because it was a mistake exposing master in this
82     * interface (master is an implementation detail). Master functions are
83     * available from HConnection or HBaseAdmin, without having to use
84     * directly the master.
85     * Deprecated in HBase 0.94
86     */
87    @Deprecated
88    public HMasterInterface getMaster()
89    throws MasterNotRunningException, ZooKeeperConnectionException;
90  
91    /** @return - true if the master server is running */
92    public boolean isMasterRunning()
93    throws MasterNotRunningException, ZooKeeperConnectionException;
94  
95    /**
96     * A table that isTableEnabled == false and isTableDisabled == false
97     * is possible. This happens when a table has a lot of regions
98     * that must be processed.
99     * @param tableName table name
100    * @return true if the table is enabled, false otherwise
101    * @throws IOException if a remote or network exception occurs
102    */
103   public boolean isTableEnabled(byte[] tableName) throws IOException;
104 
105   /**
106    * @param tableName table name
107    * @return true if the table is disabled, false otherwise
108    * @throws IOException if a remote or network exception occurs
109    */
110   public boolean isTableDisabled(byte[] tableName) throws IOException;
111 
112   /**
113    * @param tableName table name
114    * @return true if all regions of the table are available, false otherwise
115    * @throws IOException if a remote or network exception occurs
116    */
117   public boolean isTableAvailable(byte[] tableName) throws IOException;
118 
119   /**
120    * List all the userspace tables.  In other words, scan the META table.
121    *
122    * If we wanted this to be really fast, we could implement a special
123    * catalog table that just contains table names and their descriptors.
124    * Right now, it only exists as part of the META table's region info.
125    *
126    * @return - returns an array of HTableDescriptors
127    * @throws IOException if a remote or network exception occurs
128    */
129   public HTableDescriptor[] listTables() throws IOException;
130 
131   /**
132    * @param tableName table name
133    * @return table metadata
134    * @throws IOException if a remote or network exception occurs
135    */
136   public HTableDescriptor getHTableDescriptor(byte[] tableName)
137   throws IOException;
138 
139   /**
140    * Find the location of the region of <i>tableName</i> that <i>row</i>
141    * lives in.
142    * @param tableName name of the table <i>row</i> is in
143    * @param row row key you're trying to find the region of
144    * @return HRegionLocation that describes where to find the region in
145    * question
146    * @throws IOException if a remote or network exception occurs
147    */
148   public HRegionLocation locateRegion(final byte [] tableName,
149       final byte [] row)
150   throws IOException;
151 
152   /**
153    * Allows flushing the region cache.
154    */
155   public void clearRegionCache();
156 
157   /**
158    * Allows flushing the region cache of all locations that pertain to
159    * <code>tableName</code>
160    * @param tableName Name of the table whose regions we are to remove from
161    * cache.
162    */
163   public void clearRegionCache(final byte [] tableName);
164 
165   /**
166    * Find the location of the region of <i>tableName</i> that <i>row</i>
167    * lives in, ignoring any value that might be in the cache.
168    * @param tableName name of the table <i>row</i> is in
169    * @param row row key you're trying to find the region of
170    * @return HRegionLocation that describes where to find the region in
171    * question
172    * @throws IOException if a remote or network exception occurs
173    */
174   public HRegionLocation relocateRegion(final byte [] tableName,
175       final byte [] row)
176   throws IOException;
177 
178   /**
179    * Gets the location of the region of <i>regionName</i>.
180    * @param regionName name of the region to locate
181    * @return HRegionLocation that describes where to find the region in
182    * question
183    * @throws IOException if a remote or network exception occurs
184    */
185   public HRegionLocation locateRegion(final byte [] regionName)
186   throws IOException;
187 
188   /**
189    * Gets the locations of all regions in the specified table, <i>tableName</i>.
190    * @param tableName table to get regions of
191    * @return list of region locations for all regions of table
192    * @throws IOException
193    */
194   public List<HRegionLocation> locateRegions(byte[] tableName)
195   throws IOException;
196 
197   /**
198    * Establishes a connection to the region server at the specified address.
199    * @param regionServer - the server to connect to
200    * @return proxy for HRegionServer
201    * @throws IOException if a remote or network exception occurs
202    * @deprecated Use {@link #getHRegionConnection(String, int)}
203    */
204   public HRegionInterface getHRegionConnection(HServerAddress regionServer)
205   throws IOException;
206 
207   /**
208    * Establishes a connection to the region server at the specified address.
209    * @param hostname RegionServer hostname
210    * @param port RegionServer port
211    * @return proxy for HRegionServer
212    * @throws IOException if a remote or network exception occurs
213    *
214    */
215   public HRegionInterface getHRegionConnection(final String hostname, final int port)
216   throws IOException;
217 
218   /**
219    * Establishes a connection to the region server at the specified address.
220    * @param regionServer - the server to connect to
221    * @param getMaster - do we check if master is alive
222    * @return proxy for HRegionServer
223    * @throws IOException if a remote or network exception occurs
224    * @deprecated Use {@link #getHRegionConnection(HServerAddress, boolean)}
225    */
226   public HRegionInterface getHRegionConnection(HServerAddress regionServer,
227      boolean getMaster)
228   throws IOException;
229 
230   /**
231    * Establishes a connection to the region server at the specified address.
232    * @param hostname RegionServer hostname
233    * @param port RegionServer port
234    * @param getMaster - do we check if master is alive
235    * @return proxy for HRegionServer
236    * @throws IOException if a remote or network exception occurs
237    */
238   public HRegionInterface getHRegionConnection(final String hostname,
239      final int port, boolean getMaster)
240   throws IOException;
241 
242   /**
243    * Find region location hosting passed row
244    * @param tableName table name
245    * @param row Row to find.
246    * @param reload If true do not use cache, otherwise bypass.
247    * @return Location of row.
248    * @throws IOException if a remote or network exception occurs
249    */
250   HRegionLocation getRegionLocation(byte [] tableName, byte [] row,
251     boolean reload)
252   throws IOException;
253 
254   /**
255    * Pass in a ServerCallable with your particular bit of logic defined and
256    * this method will manage the process of doing retries with timed waits
257    * and refinds of missing regions.
258    *
259    * @param <T> the type of the return value
260    * @param callable callable to run
261    * @return an object of type T
262    * @throws IOException if a remote or network exception occurs
263    * @throws RuntimeException other unspecified error
264    * @deprecated Use {@link HConnectionManager#withoutRetries(ServerCallable)}
265    */
266   public <T> T getRegionServerWithRetries(ServerCallable<T> callable)
267   throws IOException, RuntimeException;
268 
269   /**
270    * Pass in a ServerCallable with your particular bit of logic defined and
271    * this method will pass it to the defined region server.
272    * @param <T> the type of the return value
273    * @param callable callable to run
274    * @return an object of type T
275    * @throws IOException if a remote or network exception occurs
276    * @throws RuntimeException other unspecified error
277    * @deprecated Use {@link HConnectionManager#withoutRetries(ServerCallable)}
278    */
279   public <T> T getRegionServerWithoutRetries(ServerCallable<T> callable)
280   throws IOException, RuntimeException;
281 
282   /**
283    * Process a mixed batch of Get, Put and Delete actions. All actions for a
284    * RegionServer are forwarded in one RPC call.
285    *
286    *
287    * @param actions The collection of actions.
288    * @param tableName Name of the hbase table
289    * @param pool thread pool for parallel execution
290    * @param results An empty array, same size as list. If an exception is thrown,
291    * you can test here for partial results, and to determine which actions
292    * processed successfully.
293    * @throws IOException if there are problems talking to META. Per-item
294    * exceptions are stored in the results array.
295    */
296   public void processBatch(List<? extends Row> actions, final byte[] tableName,
297       ExecutorService pool, Object[] results)
298       throws IOException, InterruptedException;
299 
300   /**
301    * Parameterized batch processing, allowing varying return types for different
302    * {@link Row} implementations.
303    */
304   public <R> void processBatchCallback(List<? extends Row> list,
305       byte[] tableName,
306       ExecutorService pool,
307       Object[] results,
308       Batch.Callback<R> callback) throws IOException, InterruptedException;
309 
310 
311   /**
312    * Executes the given
313    * {@link org.apache.hadoop.hbase.client.coprocessor.Batch.Call}
314    * callable for each row in the given list and invokes
315    * {@link org.apache.hadoop.hbase.client.coprocessor.Batch.Callback#update(byte[], byte[], Object)}
316    * for each result returned.
317    *
318    * @param protocol the protocol interface being called
319    * @param rows a list of row keys for which the callable should be invoked
320    * @param tableName table name for the coprocessor invoked
321    * @param pool ExecutorService used to submit the calls per row
322    * @param call instance on which to invoke
323    * {@link org.apache.hadoop.hbase.client.coprocessor.Batch.Call#call(Object)}
324    * for each row
325    * @param callback instance on which to invoke
326    * {@link org.apache.hadoop.hbase.client.coprocessor.Batch.Callback#update(byte[], byte[], Object)}
327    * for each result
328    * @param <T> the protocol interface type
329    * @param <R> the callable's return type
330    * @throws IOException
331    */
332   public <T extends CoprocessorProtocol,R> void processExecs(
333       final Class<T> protocol,
334       List<byte[]> rows,
335       final byte[] tableName,
336       ExecutorService pool,
337       final Batch.Call<T,R> call,
338       final Batch.Callback<R> callback) throws IOException, Throwable;
339 
340   /**
341    * Enable or disable region cache prefetch for the table. It will be
342    * applied for the given table's all HTable instances within this
343    * connection. By default, the cache prefetch is enabled.
344    * @param tableName name of table to configure.
345    * @param enable Set to true to enable region cache prefetch.
346    */
347   public void setRegionCachePrefetch(final byte[] tableName,
348       final boolean enable);
349 
350   /**
351    * Check whether region cache prefetch is enabled or not.
352    * @param tableName name of table to check
353    * @return true if table's region cache prefetch is enabled. Otherwise
354    * it is disabled.
355    */
356   public boolean getRegionCachePrefetch(final byte[] tableName);
357 
358   /**
359    * Load the region map and warm up the global region cache for the table.
360    * @param tableName name of the table to perform region cache prewarm.
361    * @param regions a region map.
362    */
363   public void prewarmRegionCache(final byte[] tableName,
364       final Map<HRegionInfo, HServerAddress> regions);
365 
366   /**
367    * Scan zookeeper to get the number of region servers
368    * @return the number of region servers that are currently running
369    * @throws IOException if a remote or network exception occurs
370    * @deprecated This method will be changed from public to package protected.
371    */
372   public int getCurrentNrHRS() throws IOException;
373 
374   /**
375    * @param tableNames List of table names
376    * @return HTD[] table metadata
377    * @throws IOException if a remote or network exception occurs
378    */
379   public HTableDescriptor[] getHTableDescriptors(List<String> tableNames)
380   throws IOException;
381 
382   /**
383    * @return true if this connection is closed
384    */
385   public boolean isClosed();
386 
387   /**
388    * Clear any caches that pertain to server name <code>sn</code>
389    * @param sn A server name as hostname:port
390    */
391   public void clearCaches(final String sn);
392 }