HADOOP-16192. Fix CallQueue backoff bugs: perform backoff when add() is used and update backoff when refreshed.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/CallQueueManager.java

@@ -222,12 +222,21 @@ public class CallQueueManager<E extends Schedulable>
     } else if (shouldBackOff(e)) {
       throwBackoff();
     } else {
-      add(e);
+      // No need to re-check backoff criteria since they were just checked
+      addInternal(e, false);
     }
   }
 
   @Override
   public boolean add(E e) {
+    return addInternal(e, true);
+  }
+
+  @VisibleForTesting
+  boolean addInternal(E e, boolean checkBackoff) {
+    if (checkBackoff && isClientBackoffEnabled() && shouldBackOff(e)) {
+      throwBackoff();
+    }
     try {
       return putRef.get().add(e);
     } catch (CallQueueOverflowException ex) {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java

@@ -698,6 +698,7 @@ public abstract class Server {
         CommonConfigurationKeys.IPC_SERVER_HANDLER_QUEUE_SIZE_DEFAULT);
     callQueue.swapQueue(getSchedulerClass(prefix, conf),
         getQueueClass(prefix, conf), maxQueueSize, prefix, conf);
+    callQueue.setClientBackoffEnabled(getClientBackoffEnable(prefix, conf));
   }
 
   /**

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestCallQueueManager.java

@@ -434,5 +434,18 @@ public class TestCallQueueManager {
     }
     verify(queue, times(0)).put(call);
     verify(queue, times(0)).add(call);
+
+    // backoff is enabled, add + scheduler backoff = overflow exception.
+    reset(queue);
+    cqm.setClientBackoffEnabled(true);
+    doReturn(Boolean.TRUE).when(cqm).shouldBackOff(call);
+    try {
+      cqm.add(call);
+      fail("didn't fail");
+    } catch (Exception ex) {
+      assertTrue(ex.toString(), ex instanceof CallQueueOverflowException);
+    }
+    verify(queue, times(0)).put(call);
+    verify(queue, times(0)).add(call);
   }
 }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestRPC.java

@@ -95,6 +95,7 @@ import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.timeout;
 import static org.mockito.Mockito.verify;
@@ -1133,7 +1134,7 @@ public class TestRPC extends TestRpcBase {
                 return null;
               }
             }));
-        verify(spy, timeout(500).times(i + 1)).add(any());
+        verify(spy, timeout(500).times(i + 1)).addInternal(any(), eq(false));
       }
       try {
         proxy.sleep(null, newSleepRequest(100));
@@ -1204,7 +1205,7 @@ public class TestRPC extends TestRpcBase {
                 return null;
               }
             }));
-        verify(spy, timeout(500).times(i + 1)).add(any());
+        verify(spy, timeout(500).times(i + 1)).addInternal(any(), eq(false));
       }
       // Start another sleep RPC call and verify the call is backed off due to
       // avg response time(3s) exceeds threshold (2s).