001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.client.example;
019
020import java.util.concurrent.CompletableFuture;
021import java.util.concurrent.CountDownLatch;
022import java.util.concurrent.ExecutorService;
023import java.util.concurrent.Executors;
024import java.util.concurrent.atomic.AtomicReference;
025import java.util.stream.IntStream;
026import org.apache.commons.io.IOUtils;
027import org.apache.hadoop.conf.Configured;
028import org.apache.hadoop.hbase.TableName;
029import org.apache.hadoop.hbase.client.AsyncConnection;
030import org.apache.hadoop.hbase.client.AsyncTable;
031import org.apache.hadoop.hbase.client.ConnectionFactory;
032import org.apache.hadoop.hbase.client.Get;
033import org.apache.hadoop.hbase.client.Put;
034import org.apache.hadoop.hbase.util.Bytes;
035import org.apache.hadoop.hbase.util.Threads;
036import org.apache.hadoop.util.Tool;
037import org.apache.hadoop.util.ToolRunner;
038import org.apache.yetus.audience.InterfaceAudience;
039import org.slf4j.Logger;
040import org.slf4j.LoggerFactory;
041
042/**
043 * A simple example shows how to use asynchronous client.
044 */
045@InterfaceAudience.Private
046public class AsyncClientExample extends Configured implements Tool {
047
048  private static final Logger LOG = LoggerFactory.getLogger(AsyncClientExample.class);
049
050  /**
051   * The size for thread pool.
052   */
053  private static final int THREAD_POOL_SIZE = 16;
054
055  /**
056   * The default number of operations.
057   */
058  private static final int DEFAULT_NUM_OPS = 100;
059
060  /**
061   * The name of the column family. d for default.
062   */
063  private static final byte[] FAMILY = Bytes.toBytes("d");
064
065  /**
066   * For the example we're just using one qualifier.
067   */
068  private static final byte[] QUAL = Bytes.toBytes("test");
069
070  private final AtomicReference<CompletableFuture<AsyncConnection>> future =
071      new AtomicReference<>();
072
073  private CompletableFuture<AsyncConnection> getConn() {
074    CompletableFuture<AsyncConnection> f = future.get();
075    if (f != null) {
076      return f;
077    }
078    for (;;) {
079      if (future.compareAndSet(null, new CompletableFuture<>())) {
080        CompletableFuture<AsyncConnection> toComplete = future.get();
081        ConnectionFactory.createAsyncConnection(getConf()).whenComplete((conn, error) -> {
082          if (error != null) {
083            toComplete.completeExceptionally(error);
084            // we need to reset the future holder so we will get a chance to recreate an async
085            // connection at next try.
086            future.set(null);
087            return;
088          }
089          toComplete.complete(conn);
090        });
091        return toComplete;
092      } else {
093        f = future.get();
094        if (f != null) {
095          return f;
096        }
097      }
098    }
099  }
100
101  @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="NP_NONNULL_PARAM_VIOLATION",
102      justification="it is valid to pass NULL to CompletableFuture#completedFuture")
103  private CompletableFuture<Void> closeConn() {
104    CompletableFuture<AsyncConnection> f = future.get();
105    if (f == null) {
106      return CompletableFuture.completedFuture(null);
107    }
108    CompletableFuture<Void> closeFuture = new CompletableFuture<>();
109    f.whenComplete((conn, error) -> {
110      if (error == null) {
111        IOUtils.closeQuietly(conn);
112      }
113      closeFuture.complete(null);
114    });
115    return closeFuture;
116  }
117
118  private byte[] getKey(int i) {
119    return Bytes.toBytes(String.format("%08x", i));
120  }
121
122  @Override
123  public int run(String[] args) throws Exception {
124    if (args.length < 1 || args.length > 2) {
125      System.out.println("Usage: " + this.getClass().getName() + " tableName [num_operations]");
126      return -1;
127    }
128    TableName tableName = TableName.valueOf(args[0]);
129    int numOps = args.length > 1 ? Integer.parseInt(args[1]) : DEFAULT_NUM_OPS;
130    ExecutorService threadPool = Executors.newFixedThreadPool(THREAD_POOL_SIZE,
131      Threads.newDaemonThreadFactory("AsyncClientExample"));
132    // We use AsyncTable here so we need to provide a separated thread pool. RawAsyncTable does not
133    // need a thread pool and may have a better performance if you use it correctly as it can save
134    // some context switches. But if you use RawAsyncTable incorrectly, you may have a very bad
135    // impact on performance so use it with caution.
136    CountDownLatch latch = new CountDownLatch(numOps);
137    IntStream.range(0, numOps).forEach(i -> {
138      CompletableFuture<AsyncConnection> future = getConn();
139      future.whenComplete((conn, error) -> {
140        if (error != null) {
141          LOG.warn("failed to get async connection for " + i, error);
142          latch.countDown();
143          return;
144        }
145        AsyncTable<?> table = conn.getTable(tableName, threadPool);
146        table.put(new Put(getKey(i)).addColumn(FAMILY, QUAL, Bytes.toBytes(i)))
147            .whenComplete((putResp, putErr) -> {
148              if (putErr != null) {
149                LOG.warn("put failed for " + i, putErr);
150                latch.countDown();
151                return;
152              }
153              LOG.info("put for " + i + " succeeded, try getting");
154              table.get(new Get(getKey(i))).whenComplete((result, getErr) -> {
155                if (getErr != null) {
156                  LOG.warn("get failed for " + i);
157                  latch.countDown();
158                  return;
159                }
160                if (result.isEmpty()) {
161                  LOG.warn("get failed for " + i + ", server returns empty result");
162                } else if (!result.containsColumn(FAMILY, QUAL)) {
163                  LOG.warn("get failed for " + i + ", the result does not contain " +
164                      Bytes.toString(FAMILY) + ":" + Bytes.toString(QUAL));
165                } else {
166                  int v = Bytes.toInt(result.getValue(FAMILY, QUAL));
167                  if (v != i) {
168                    LOG.warn("get failed for " + i + ", the value of " + Bytes.toString(FAMILY) +
169                        ":" + Bytes.toString(QUAL) + " is " + v + ", exected " + i);
170                  } else {
171                    LOG.info("get for " + i + " succeeded");
172                  }
173                }
174                latch.countDown();
175              });
176            });
177      });
178    });
179    latch.await();
180    closeConn().get();
181    return 0;
182  }
183
184  public static void main(String[] args) throws Exception {
185    ToolRunner.run(new AsyncClientExample(), args);
186  }
187}