code: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.hadoop.hdfs.server.federation.fairness;
  
  import static org.apache.hadoop.test.GenericTestUtils.assertExceptionContains;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertTrue;
  
  import java.io.IOException;
  import java.net.URI;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hdfs.DFSClient;
  import org.apache.hadoop.hdfs.HdfsConfiguration;
  import org.apache.hadoop.hdfs.protocol.ClientProtocol;
  import org.apache.hadoop.hdfs.server.federation.MiniRouterDFSCluster.RouterContext;
  import org.apache.hadoop.hdfs.server.federation.RouterConfigBuilder;
  import org.apache.hadoop.hdfs.server.federation.StateStoreDFSCluster;
  import org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys;
  import org.apache.hadoop.ipc.RemoteException;
  import org.apache.hadoop.ipc.StandbyException;
  import org.junit.After;
  import org.junit.Test;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Test the Router handlers fairness control rejects
   * requests when the handlers are overloaded.
   */
  public class TestRouterHandlersFairness {
  
    private static final Logger LOG =
        LoggerFactory.getLogger(TestRouterHandlersFairness.class);
  
    private StateStoreDFSCluster cluster;
  
    @After
    public void cleanup() {
      if (cluster != null) {
        cluster.shutdown();
        cluster = null;
      }
    }
  
    private void setupCluster(boolean fairnessEnable, boolean ha)
        throws Exception {
      // Build and start a federated cluster
      cluster = new StateStoreDFSCluster(ha, 2);
      Configuration routerConf = new RouterConfigBuilder()
          .stateStore()
          .rpc()
          .build();
  
      // Fairness control
      if (fairnessEnable) {
        routerConf.setClass(
            RBFConfigKeys.DFS_ROUTER_FAIRNESS_POLICY_CONTROLLER_CLASS,
            StaticRouterRpcFairnessPolicyController.class,
            RouterRpcFairnessPolicyController.class);
      }
  
      // With two name services configured, each nameservice has 1 permit and
      // fan-out calls have 1 permit.
      routerConf.setInt(RBFConfigKeys.DFS_ROUTER_HANDLER_COUNT_KEY, 3);
  
      // Datanodes not needed for this test.
      cluster.setNumDatanodesPerNameservice(0);
  
      cluster.addRouterOverrides(routerConf);
      cluster.startCluster();
      cluster.startRouters();
      cluster.waitClusterUp();
    }
  
    @Test
    public void testFairnessControlOff() throws Exception {
      setupCluster(false, false);
      startLoadTest(false);
    }
  
    @Test
    public void testFairnessControlOn() throws Exception {
      setupCluster(true, false);
      startLoadTest(true);
    }
  
    /**
     * Start a generic load test as a client against a cluster which has either
     * fairness configured or not configured. Test will spawn a set of 100
     * threads to simulate concurrent request to test routers. If fairness is
     * enabled, the test will successfully report the failure of some threads
     * to continue with StandbyException. If fairness is not configured, all
     * threads of the same test should successfully complete all the rpcs.
     *
     * @param fairness Flag to indicate if fairness management is on/off.
     * @throws Exception Throws exception.
     */
    private void startLoadTest(boolean fairness)
        throws Exception {
  
      // Concurrent requests
      startLoadTest(true, fairness);
  
      // Sequential requests
      startLoadTest(false, fairness);
    }
  
    private void startLoadTest(final boolean isConcurrent, final boolean fairness)
        throws Exception {
  
      RouterContext routerContext = cluster.getRandomRouter();
      if (fairness) {
        if (isConcurrent) {
          LOG.info("Taking fanout lock first");
          // take the lock for concurrent NS to block fanout calls
          assertTrue(routerContext.getRouter().getRpcServer()
              .getRPCClient().getRouterRpcFairnessPolicyController()
              .acquirePermit(RouterRpcFairnessConstants.CONCURRENT_NS));
        } else {
          for (String ns : cluster.getNameservices()) {
            LOG.info("Taking lock first for ns: {}", ns);
            assertTrue(routerContext.getRouter().getRpcServer()
                .getRPCClient().getRouterRpcFairnessPolicyController()
                .acquirePermit(ns));
          }
        }
      }
      URI address = routerContext.getFileSystemURI();
      Configuration conf = new HdfsConfiguration();
      final int numOps = 10;
      final AtomicInteger overloadException = new AtomicInteger();
  
      for (int i = 0; i < numOps; i++) {
        DFSClient routerClient = null;
        try {
          routerClient = new DFSClient(address, conf);
          String clientName = routerClient.getClientName();
          ClientProtocol routerProto = routerClient.getNamenode();
          if (isConcurrent) {
            invokeConcurrent(routerProto, clientName);
          } else {
            invokeSequential(routerProto);
          }
        } catch (RemoteException re) {
          IOException ioe = re.unwrapRemoteException();
          assertTrue("Wrong exception: " + ioe,
              ioe instanceof StandbyException);
          assertExceptionContains("is overloaded for NS", ioe);
          overloadException.incrementAndGet();
        } catch (Throwable e) {
          throw e;
        } finally {
          if (routerClient != null) {
            try {
              routerClient.close();
            } catch (IOException e) {
              LOG.error("Cannot close the client");
            }
          }
        }
        overloadException.get();
      }
  
      if (fairness) {
        assertTrue(overloadException.get() > 0);
        if (isConcurrent) {
          LOG.info("Release fanout lock that was taken before test");
          // take the lock for concurrent NS to block fanout calls
          routerContext.getRouter().getRpcServer()
              .getRPCClient().getRouterRpcFairnessPolicyController()
              .releasePermit(RouterRpcFairnessConstants.CONCURRENT_NS);
        } else {
          for (String ns : cluster.getNameservices()) {
            routerContext.getRouter().getRpcServer()
                .getRPCClient().getRouterRpcFairnessPolicyController()
                .releasePermit(ns);
          }
        }
      } else {
        assertEquals("Number of failed RPCs without fairness configured",
            0, overloadException.get());
      }
    }
  
    private void invokeSequential(ClientProtocol routerProto) throws IOException {
      routerProto.getFileInfo("/test.txt");
    }
  
    private void invokeConcurrent(ClientProtocol routerProto, String clientName)
        throws IOException {
      routerProto.renewLease(clientName);
    }
  
  }
  