HDFS-16273. RBF: RouterRpcFairnessPolicyController add availableHandleOnPerNs metrics (#3553)

Reviewed-by: Inigo Goiri <inigoiri@apache.org>
Reviewed-by: Hui Fei <ferhui@apache.org>

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/fairness/AbstractRouterRpcFairnessPolicyController.java

@@ -23,6 +23,8 @@ import java.util.Map;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 
+import org.codehaus.jettison.json.JSONException;
+import org.codehaus.jettison.json.JSONObject;
 import org.apache.hadoop.conf.Configuration;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -75,4 +77,19 @@ public class AbstractRouterRpcFairnessPolicyController
   protected int getAvailablePermits(String nsId) {
     return this.permits.get(nsId).availablePermits();
   }
+
+  @Override
+  public String getAvailableHandlerOnPerNs() {
+    JSONObject json = new JSONObject();
+    for (Map.Entry<String, Semaphore> entry : permits.entrySet()) {
+      try {
+        String nsId = entry.getKey();
+        int availableHandler = entry.getValue().availablePermits();
+        json.put(nsId, availableHandler);
+      } catch (JSONException e) {
+        LOG.warn("Cannot put {} into JSONObject", entry.getKey(), e);
+      }
+    }
+    return json.toString();
+  }
 }

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/fairness/NoRouterRpcFairnessPolicyController.java

@@ -46,4 +46,9 @@ public class NoRouterRpcFairnessPolicyController implements
   public void shutdown() {
     // Nothing for now.
   }
+
+  @Override
+  public String getAvailableHandlerOnPerNs(){
+    return "N/A";
+  }
 }

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/fairness/RouterRpcFairnessPolicyController.java

@@ -62,4 +62,9 @@ public interface RouterRpcFairnessPolicyController {
    * Shutdown steps to stop accepting new permission requests and clean-up.
    */
   void shutdown();
+
+  /**
+   * Returns the JSON string of the available handler for each Ns.
+   */
+  String getAvailableHandlerOnPerNs();
 }

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/metrics/FederationRPCMBean.java

@@ -109,6 +109,12 @@ public interface FederationRPCMBean {
    */
   String getRpcClientConnections();
 
+  /**
+   * JSON representation of the available handler per Ns.
+   * @return JSON string representation.
+   */
+  String getAvailableHandlerOnPerNs();
+
   /**
    * Get the JSON representation of the async caller thread pool.
    * @return JSON string representation of the async caller thread pool.

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/metrics/FederationRPCMetrics.java

@@ -233,6 +233,12 @@ public class FederationRPCMetrics implements FederationRPCMBean {
     return rpcServer.getRPCClient().getJSON();
   }
 
+  @Override
+  public String getAvailableHandlerOnPerNs() {
+    return rpcServer.getRPCClient().
+        getRouterRpcFairnessPolicyController().getAvailableHandlerOnPerNs();
+  }
+
   @Override
   public String getAsyncCallerPool() {
     return rpcServer.getRPCClient().getAsyncCallerPoolJson();

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcClient.java

@@ -64,7 +64,6 @@ import org.apache.hadoop.hdfs.NameNodeProxiesClient.ProxyAndInfo;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.SnapshotException;
-import org.apache.hadoop.hdfs.server.federation.fairness.AbstractRouterRpcFairnessPolicyController;
 import org.apache.hadoop.hdfs.server.federation.fairness.RouterRpcFairnessPolicyController;
 import org.apache.hadoop.hdfs.server.federation.resolver.ActiveNamenodeResolver;
 import org.apache.hadoop.hdfs.server.federation.resolver.FederationNamenodeContext;
@@ -1584,10 +1583,9 @@ public class RouterRpcClient {
   }
 
   @VisibleForTesting
-  public AbstractRouterRpcFairnessPolicyController
+  public RouterRpcFairnessPolicyController
       getRouterRpcFairnessPolicyController() {
-    return (AbstractRouterRpcFairnessPolicyController
-          )routerRpcFairnessPolicyController;
+    return routerRpcFairnessPolicyController;
   }
 
   private void incrRejectedPermitForNs(String ns) {

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/fairness/TestRouterRpcFairnessPolicyController.java

@@ -30,6 +30,7 @@ import static org.apache.hadoop.hdfs.server.federation.fairness.RouterRpcFairnes
 import static org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys.DFS_ROUTER_HANDLER_COUNT_KEY;
 import static org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys.DFS_ROUTER_MONITOR_NAMENODE;
 import static org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys.DFS_ROUTER_FAIR_HANDLER_COUNT_KEY_PREFIX;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -101,6 +102,26 @@ public class TestRouterRpcFairnessPolicyController {
     verifyInstantiationError(conf, 1, 3);
   }
 
+  @Test
+  public void testGetAvailableHandlerOnPerNs() {
+    RouterRpcFairnessPolicyController routerRpcFairnessPolicyController
+        = getFairnessPolicyController(30);
+    assertEquals("{\"concurrent\":10,\"ns2\":10,\"ns1\":10}",
+        routerRpcFairnessPolicyController.getAvailableHandlerOnPerNs());
+    routerRpcFairnessPolicyController.acquirePermit("ns1");
+    assertEquals("{\"concurrent\":10,\"ns2\":10,\"ns1\":9}",
+        routerRpcFairnessPolicyController.getAvailableHandlerOnPerNs());
+  }
+
+  @Test
+  public void testGetAvailableHandlerOnPerNsForNoFairness() {
+    Configuration conf = new Configuration();
+    RouterRpcFairnessPolicyController routerRpcFairnessPolicyController =
+        FederationUtil.newFairnessPolicyController(conf);
+    assertEquals("N/A",
+        routerRpcFairnessPolicyController.getAvailableHandlerOnPerNs());
+  }
+
   @Test
   public void testAllocationErrorForLowPreconfiguredHandlers() {
     Configuration conf = createConf(1);