HBASE-25860 Add metric for successful wal roll requests. (#3241)

Signed-off-by: Viraj Jasani <vjasani@apache.org>

hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/regionserver/wal/MetricsWALSource.java

@@ -74,6 +74,8 @@ public interface MetricsWALSource extends BaseSource {
       "How many times a roll was requested due to file size roll threshold.";
   String WRITTEN_BYTES = "writtenBytes";
   String WRITTEN_BYTES_DESC = "Size (in bytes) of the data written to the WAL.";
+  String SUCCESSFUL_LOG_ROLLS = "successfulLogRolls";
+  String SUCCESSFUL_LOG_ROLLS_DESC = "Number of successful log rolls requests";
 
   /**
    * Add the append size.
@@ -111,4 +113,11 @@ public interface MetricsWALSource extends BaseSource {
   void incrementSizeLogRoll();
 
   void incrementWrittenBytes(long val);
+
+  /**
+   * Increment the number of successful log roll requests.
+   */
+  void incrementSuccessfulLogRolls();
+
+  long getSuccessfulLogRolls();
 }

hbase-hadoop2-compat/src/main/java/org/apache/hadoop/hbase/regionserver/wal/MetricsWALSourceImpl.java

@@ -47,6 +47,7 @@ public class MetricsWALSourceImpl extends BaseSourceImpl implements MetricsWALSo
   private final MutableFastCounter slowSyncRollRequested;
   private final MutableFastCounter sizeRollRequested;
   private final MutableFastCounter writtenBytes;
+  private final MutableFastCounter successfulLogRolls;
   // Per table metrics.
   private final ConcurrentMap<TableName, MutableFastCounter> perTableAppendCount;
   private final ConcurrentMap<TableName, MutableFastCounter> perTableAppendSize;
@@ -79,6 +80,8 @@ public class MetricsWALSourceImpl extends BaseSourceImpl implements MetricsWALSo
     sizeRollRequested = this.getMetricsRegistry()
         .newCounter(SIZE_ROLL_REQUESTED, SIZE_ROLL_REQUESTED_DESC, 0L);
     writtenBytes = this.getMetricsRegistry().newCounter(WRITTEN_BYTES, WRITTEN_BYTES_DESC, 0L);
+    successfulLogRolls = this.getMetricsRegistry()
+      .newCounter(SUCCESSFUL_LOG_ROLLS, SUCCESSFUL_LOG_ROLLS_DESC, 0L);
     perTableAppendCount = new ConcurrentHashMap<>();
     perTableAppendSize = new ConcurrentHashMap<>();
   }
@@ -155,4 +158,14 @@ public class MetricsWALSourceImpl extends BaseSourceImpl implements MetricsWALSo
   public void incrementWrittenBytes(long val) {
     writtenBytes.incr(val);
   }
+
+  @Override
+  public void incrementSuccessfulLogRolls() {
+    successfulLogRolls.incr();
+  }
+
+  @Override
+  public long getSuccessfulLogRolls() {
+    return successfulLogRolls.value();
+  }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/MetricsWAL.java

@@ -23,6 +23,7 @@ import java.io.IOException;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hbase.classification.InterfaceAudience;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.wal.WALKey;
@@ -90,4 +91,13 @@ public class MetricsWAL extends WALActionsListener.Base {
         break;
     }
   }
+
+  @Override
+  public void postLogRoll(Path oldPath, Path newPath) {
+    // oldPath can be null if this is the first time we created a wal
+    // Also newPath can be equal to oldPath if AbstractFSWAL#replaceWriter fails
+    if (newPath != oldPath) {
+      source.incrementSuccessfulLogRolls();
+    }
+  }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestMetricsWAL.java

@@ -18,14 +18,17 @@
 
 package org.apache.hadoop.hbase.regionserver.wal;
 
+import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hbase.testclassification.SmallTests;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.wal.WALKey;
 import org.apache.hadoop.metrics2.lib.DynamicMetricsRegistry;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
+import org.junit.rules.TestName;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.Mockito.mock;
@@ -34,6 +37,9 @@ import static org.mockito.Mockito.verify;
 
 @Category(SmallTests.class)
 public class TestMetricsWAL {
+  @Rule
+  public TestName name = new TestName();
+
   @Test
   public void testLogRollRequested() throws Exception {
     MetricsWALSource source = mock(MetricsWALSourceImpl.class);
@@ -110,4 +116,25 @@ public class TestMetricsWAL {
       assertEquals(i * numIters, tableAppendSize);
     }
   }
+
+  @Test
+  public void testLogRolls() {
+    String testName = name.getMethodName();
+    MetricsWALSource source = new MetricsWALSourceImpl(testName, testName, testName, testName);
+    MetricsWAL metricsWAL = new MetricsWAL(source);
+    Path path1 = new Path("path-1");
+    int count = 1;
+    // oldPath is null but newPath is not null;
+    metricsWAL.postLogRoll(null, path1);
+    assertEquals(count, source.getSuccessfulLogRolls());
+
+    // Simulating a case where AbstractFSWAL#replaceWriter fails
+    metricsWAL.postLogRoll(path1, path1);
+    assertEquals(count, source.getSuccessfulLogRolls());
+
+    count++;
+    Path path2 = new Path("path-2");
+    metricsWAL.postLogRoll(path1, path2);
+    assertEquals(count, source.getSuccessfulLogRolls());
+  }
 }