HBASE-25561 Added ignored test for async connection that runs retries just so can check how long it takes and that retrying is happening (#2942)

hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestClientNoCluster.java

@@ -30,6 +30,7 @@ import java.util.Random;
 import java.util.SortedMap;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -104,6 +105,7 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos.RegionSpeci
 /**
  * Test client behavior w/o setting up a cluster.
  * Mock up cluster emissions.
+ * See below for a method that tests retries/timeouts currently commented out.
  */
 @Category({ClientTests.class, SmallTests.class})
 public class TestClientNoCluster extends Configured implements Tool {
@@ -114,6 +116,12 @@ public class TestClientNoCluster extends Configured implements Tool {
 
   private static final Logger LOG = LoggerFactory.getLogger(TestClientNoCluster.class);
   private Configuration conf;
+  /**
+   * A server that does not exist. I've changed the server in the below to 'localhost' so we
+   * have a servername that resolves -- otherwise, we just fail on server name lookup with
+   * UnknownHost... With localhost, was able to reproduce stack traces that looked like production
+   * stack traces. Was useful figuring out how retry/timeouts are functioning.
+   */
   public static final ServerName META_SERVERNAME =
       ServerName.valueOf("meta.example.org", 16010, 12345);
 
@@ -149,8 +157,7 @@ public class TestClientNoCluster extends Configured implements Tool {
   }
 
   /**
-   * Remove the @Ignore to try out timeout and retry asettings
-   * @throws IOException
+   * Remove the @Ignore to try out timeout and retry settings
    */
   @Ignore
   @Test
@@ -158,6 +165,7 @@ public class TestClientNoCluster extends Configured implements Tool {
     Configuration localConfig = HBaseConfiguration.create(this.conf);
     // This override mocks up our exists/get call to throw a RegionServerStoppedException.
     localConfig.set("hbase.client.connection.impl", RpcTimeoutConnection.class.getName());
+    // localConfig.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, 7);
     Connection connection = ConnectionFactory.createConnection(localConfig);
     Table table = connection.getTable(TableName.META_TABLE_NAME);
     Throwable t = null;
@@ -180,6 +188,34 @@ public class TestClientNoCluster extends Configured implements Tool {
     assertTrue(t != null);
   }
 
+  /**
+   * Remove the @Ignore to try out timeout and retry settings
+   */
+  // @Ignore
+  @Test
+  public void testAsyncTimeoutAndRetries()
+      throws IOException, ExecutionException, InterruptedException {
+    Configuration localConfig = HBaseConfiguration.create(this.conf);
+    localConfig.set(ConnectionFactory.HBASE_CLIENT_ASYNC_CONNECTION_IMPL,
+      RpcTimeoutAsyncConnection.class.getName());
+    localConfig.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, 9);
+    AsyncConnection connection = ConnectionFactory.createAsyncConnection(localConfig).get();
+    AsyncTable table = connection.getTable(TableName.META_TABLE_NAME);
+    Throwable t = null;
+    LOG.info("Start");
+    try {
+      // An exists call turns into a get w/ a flag.
+      table.exists(new Get(Bytes.toBytes("abc"))).get();
+    } catch (Throwable throwable) {
+      // What to catch?
+      t = throwable;
+    } finally {
+      connection.close();
+    }
+    LOG.info("Stop");
+    assertTrue(t != null);
+  }
+
   /**
    * Test that operation timeout prevails over rpc default timeout and retries, etc.
    * @throws IOException
@@ -331,8 +367,7 @@ public class TestClientNoCluster extends Configured implements Tool {
   /**
    * Override to check we are setting rpc timeout right.
    */
-  static class RpcTimeoutConnection
-  extends ConnectionImplementation {
+  static class RpcTimeoutConnection extends ConnectionImplementation {
     final ClientService.BlockingInterface stub;
 
     RpcTimeoutConnection(Configuration conf, ExecutorService pool, User user)
@@ -343,7 +378,7 @@ public class TestClientNoCluster extends Configured implements Tool {
       try {
         Mockito.when(stub.get((RpcController)Mockito.any(),
             (ClientProtos.GetRequest)Mockito.any())).
-          thenThrow(new ServiceException(new RegionServerStoppedException("From Mockito")));
+          thenThrow(new ServiceException(new java.net.ConnectException("Connection refused")));
       } catch (ServiceException e) {
         throw new IOException(e);
       }
@@ -355,6 +390,16 @@ public class TestClientNoCluster extends Configured implements Tool {
     }
   }
 
+  /**
+   * Override to check we are setting rpc timeout right.
+   */
+  static class RpcTimeoutAsyncConnection extends AsyncConnectionImpl {
+    RpcTimeoutAsyncConnection(Configuration configuration, ConnectionRegistry registry,
+        String clusterId, User user) {
+      super(configuration, registry, clusterId, user);
+    }
+  }
+
   /**
    * Fake many regionservers and many regions on a connection implementation.
    */