HBASE-16834 Add AsyncConnection support for ConnectionFactory

hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionFactory.java

@@ -28,6 +28,7 @@ import org.apache.hadoop.hbase.classification.InterfaceAudience;
 import org.apache.hadoop.hbase.classification.InterfaceStability;
 import org.apache.hadoop.hbase.security.User;
 import org.apache.hadoop.hbase.security.UserProvider;
+import org.apache.hadoop.hbase.util.ReflectionUtils;
 
 
 /**
@@ -57,6 +58,9 @@ import org.apache.hadoop.hbase.security.UserProvider;
 @InterfaceStability.Evolving
 public class ConnectionFactory {
 
+  public static final String HBASE_CLIENT_ASYNC_CONNECTION_IMPL =
+      "hbase.client.async.connection.impl";
+
   /** No public c.tors */
   protected ConnectionFactory() {
   }
@@ -233,4 +237,53 @@ public class ConnectionFactory {
       throw new IOException(e);
     }
   }
+
+  /**
+   * Call {@link #createAsyncConnection(Configuration)} using default HBaseConfiguration.
+   * @see #createAsyncConnection(Configuration)
+   * @return AsyncConnection object
+   */
+  public static AsyncConnection createAsyncConnection() throws IOException {
+    return createAsyncConnection(HBaseConfiguration.create());
+  }
+
+  /**
+   * Call {@link #createAsyncConnection(Configuration, User)} using the given {@code conf} and a
+   * User object created by {@link UserProvider}. The given {@code conf} will also be used to
+   * initialize the {@link UserProvider}.
+   * @param conf configuration
+   * @return AsyncConnection object
+   * @see #createAsyncConnection(Configuration, User)
+   * @see UserProvider
+   */
+  public static AsyncConnection createAsyncConnection(Configuration conf) throws IOException {
+    return createAsyncConnection(conf, UserProvider.instantiate(conf).getCurrent());
+  }
+
+  /**
+   * Create a new AsyncConnection instance using the passed {@code conf} and {@code user}.
+   * AsyncConnection encapsulates all housekeeping for a connection to the cluster. All tables and
+   * interfaces created from returned connection share zookeeper connection, meta cache, and
+   * connections to region servers and masters.
+   * <p>
+   * The caller is responsible for calling {@link AsyncConnection#close()} on the returned
+   * connection instance.
+   * <p>
+   * Usually you should only create one AsyncConnection instance in your code and use it everywhere
+   * as it is thread safe.
+   * @param conf configuration
+   * @param user the user the asynchronous connection is for
+   * @return AsyncConnection object
+   * @throws IOException
+   */
+  public static AsyncConnection createAsyncConnection(Configuration conf, User user)
+      throws IOException {
+    Class<? extends AsyncConnection> clazz = conf.getClass(HBASE_CLIENT_ASYNC_CONNECTION_IMPL,
+      AsyncConnectionImpl.class, AsyncConnection.class);
+    try {
+      return ReflectionUtils.newInstance(clazz, conf, user);
+    } catch (Exception e) {
+      throw new IOException(e);
+    }
+  }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTable.java

@@ -28,7 +28,6 @@ import java.util.stream.IntStream;
 
 import org.apache.hadoop.hbase.HBaseTestingUtility;
 import org.apache.hadoop.hbase.TableName;
-import org.apache.hadoop.hbase.security.User;
 import org.apache.hadoop.hbase.testclassification.ClientTests;
 import org.apache.hadoop.hbase.testclassification.MediumTests;
 import org.apache.hadoop.hbase.util.Bytes;
@@ -60,7 +59,7 @@ public class TestAsyncTable {
     TEST_UTIL.startMiniCluster(1);
     TEST_UTIL.createTable(TABLE_NAME, FAMILY);
     TEST_UTIL.waitTableAvailable(TABLE_NAME);
-    ASYNC_CONN = new AsyncConnectionImpl(TEST_UTIL.getConfiguration(), User.getCurrent());
+    ASYNC_CONN = ConnectionFactory.createAsyncConnection(TEST_UTIL.getConfiguration());
   }
 
   @AfterClass