HBASE-12840 Improve unit test coverage of the client pushback mechanism

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

@@ -0,0 +1,62 @@
+/**
+ * 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.hbase.client;
+
+import static org.junit.Assert.*;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.apache.hadoop.hbase.HRegionInfo;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+@Category(SmallTests.class)
+public class TestDelayingRunner {
+
+  private static final TableName DUMMY_TABLE =
+      TableName.valueOf("DUMMY_TABLE");
+  private static final byte[] DUMMY_BYTES_1 = "DUMMY_BYTES_1".getBytes();
+  private static final byte[] DUMMY_BYTES_2 = "DUMMY_BYTES_2".getBytes();
+  private static HRegionInfo hri1 =
+      new HRegionInfo(DUMMY_TABLE, DUMMY_BYTES_1, DUMMY_BYTES_2, false, 1);
+
+  @SuppressWarnings({ "rawtypes", "unchecked" })
+  @Test
+  public void testDelayingRunner() throws Exception{
+    MultiAction<Row> ma = new MultiAction<Row>();
+    ma.add(hri1.getRegionName(), new Action<Row>(new Put(DUMMY_BYTES_1), 0));
+    final AtomicLong endTime = new AtomicLong();
+    final long sleepTime = 1000;
+    DelayingRunner runner = new DelayingRunner(sleepTime, ma.actions.entrySet().iterator().next());
+    runner.setRunner(new Runnable() {
+      @Override
+      public void run() {
+        endTime.set(EnvironmentEdgeManager.currentTime());
+      }      
+    });
+    long startTime = EnvironmentEdgeManager.currentTime();
+    runner.run();
+    long delay = endTime.get() - startTime;
+    assertTrue("DelayingRunner did not delay long enough", delay >= sleepTime);
+    assertFalse("DelayingRunner delayed too long", delay > sleepTime + sleepTime*0.2);
+  }
+
+}

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

@@ -17,22 +17,34 @@
  */
 package org.apache.hadoop.hbase.client;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.*;
+import org.apache.hadoop.hbase.client.backoff.ClientBackoffPolicy;
+import org.apache.hadoop.hbase.client.backoff.ExponentialClientBackoffPolicy;
 import org.apache.hadoop.hbase.client.backoff.ServerStatistics;
+import org.apache.hadoop.hbase.client.coprocessor.Batch;
 import org.apache.hadoop.hbase.regionserver.HRegion;
 import org.apache.hadoop.hbase.regionserver.HRegionServer;
 import org.apache.hadoop.hbase.testclassification.MediumTests;
 import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 
 /**
  * Test that we can actually send and use region metrics to slowdown client writes
@@ -53,6 +65,9 @@ public class TestClientPushback {
     Configuration conf = UTIL.getConfiguration();
     // enable backpressure
     conf.setBoolean(HConstants.ENABLE_CLIENT_BACKPRESSURE, true);
+    // use the exponential backoff policy
+    conf.setClass(ClientBackoffPolicy.BACKOFF_POLICY_CLASS, ExponentialClientBackoffPolicy.class,
+      ClientBackoffPolicy.class);
     // turn the memstore size way down so we don't need to write a lot to see changes in memstore
     // load
     conf.setLong(HConstants.HREGION_MEMSTORE_FLUSH_SIZE, flushSizeBytes);
@@ -68,7 +83,7 @@ public class TestClientPushback {
     UTIL.shutdownMiniCluster();
   }
 
-  @Test
+  @Test(timeout=60000)
   public void testClientTracksServerPushback() throws Exception{
     Configuration conf = UTIL.getConfiguration();
     TableName tablename = TableName.valueOf(tableName);
@@ -91,6 +106,10 @@ public class TestClientPushback {
 
     // get the stats for the region hosting our table
     ClusterConnection connection = table.connection;
+    ClientBackoffPolicy backoffPolicy = connection.getBackoffPolicy();
+    assertTrue("Backoff policy is not correctly configured",
+      backoffPolicy instanceof ExponentialClientBackoffPolicy);
+    
     ServerStatisticTracker stats = connection.getStatisticsTracker();
     assertNotNull( "No stats configured for the client!", stats);
     // get the names so we can query the stats
@@ -100,6 +119,35 @@ public class TestClientPushback {
     // check to see we found some load on the memstore
     ServerStatistics serverStats = stats.getServerStatsForTesting(server);
     ServerStatistics.RegionStatistics regionStats = serverStats.getStatsForRegion(regionName);
-    assertEquals(load, regionStats.getMemstoreLoadPercent());
+    assertEquals("We did not find some load on the memstore", load,
+      regionStats.getMemstoreLoadPercent());
+
+    // check that the load reported produces a nonzero delay
+    long backoffTime = backoffPolicy.getBackoffTime(server, regionName, serverStats);
+    assertNotEquals("Reported load does not produce a backoff", backoffTime, 0);
+    LOG.debug("Backoff calculated for " + region.getRegionNameAsString() + " @ " + server +
+      " is " + backoffTime);
+
+    // Reach into the connection and submit work directly to AsyncProcess so we can
+    // monitor how long the submission was delayed via a callback
+    List<Row> ops = new ArrayList<Row>(1);
+    ops.add(p);
+    final CountDownLatch latch = new CountDownLatch(1);
+    final AtomicLong endTime = new AtomicLong();
+    long startTime = EnvironmentEdgeManager.currentTime();    
+    table.ap.submit(tablename, ops, true, new Batch.Callback<Result>() {
+      @Override
+      public void update(byte[] region, byte[] row, Result result) {
+        endTime.set(EnvironmentEdgeManager.currentTime());
+        latch.countDown();
+      }
+    }, true);
+    // Currently the ExponentialClientBackoffPolicy under these test conditions
+    // produces a backoffTime of 151 milliseconds. This is long enough so the
+    // wait and related checks below are reasonable. Revisit if the backoff
+    // time reported by above debug logging has significantly deviated.
+    latch.await(backoffTime * 2, TimeUnit.MILLISECONDS);
+    assertNotEquals("AsyncProcess did not submit the work time", endTime.get(), 0);
+    assertTrue("AsyncProcess did not delay long enough", endTime.get() - startTime >= backoffTime);
   }
-}
+}