HADOOP-17016. Adding Common Counters in ABFS (#1991).

Contributed by: Mehakmeet Singh.

Change-Id: Ib84e7a42f28e064df4c6204fcce33e573360bf42

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AbfsInstrumentation.java

@@ -0,0 +1,279 @@
+/**
+ * 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.fs.azurebfs;
+
+import java.net.URI;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+import com.google.common.annotations.VisibleForTesting;
+
+import org.apache.hadoop.fs.azurebfs.services.AbfsCounters;
+import org.apache.hadoop.metrics2.AbstractMetric;
+import org.apache.hadoop.metrics2.MetricStringBuilder;
+import org.apache.hadoop.metrics2.MetricsCollector;
+import org.apache.hadoop.metrics2.MetricsInfo;
+import org.apache.hadoop.metrics2.MetricsRecordBuilder;
+import org.apache.hadoop.metrics2.MetricsTag;
+import org.apache.hadoop.metrics2.lib.MetricsRegistry;
+import org.apache.hadoop.metrics2.lib.MutableCounterLong;
+import org.apache.hadoop.metrics2.lib.MutableMetric;
+
+import static org.apache.hadoop.fs.azurebfs.AbfsStatistic.*;
+
+/**
+ * Instrumentation of Abfs counters.
+ */
+public class AbfsInstrumentation implements AbfsCounters {
+
+  /**
+   * Single context for all the Abfs counters to separate them from other
+   * counters.
+   */
+  private static final String CONTEXT = "AbfsContext";
+  /**
+   * The name of a field added to metrics records that uniquely identifies a
+   * specific FileSystem instance.
+   */
+  private static final String REGISTRY_ID = "AbfsID";
+  /**
+   * The name of a field added to metrics records that indicates the hostname
+   * portion of the FS URL.
+   */
+  private static final String METRIC_BUCKET = "AbfsBucket";
+
+  private final MetricsRegistry registry =
+      new MetricsRegistry("abfsMetrics").setContext(CONTEXT);
+
+  private static final AbfsStatistic[] STATISTIC_LIST = {
+      CALL_CREATE,
+      CALL_OPEN,
+      CALL_GET_FILE_STATUS,
+      CALL_APPEND,
+      CALL_CREATE_NON_RECURSIVE,
+      CALL_DELETE,
+      CALL_EXIST,
+      CALL_GET_DELEGATION_TOKEN,
+      CALL_LIST_STATUS,
+      CALL_MKDIRS,
+      CALL_RENAME,
+      DIRECTORIES_CREATED,
+      DIRECTORIES_DELETED,
+      FILES_CREATED,
+      FILES_DELETED,
+      ERROR_IGNORED
+  };
+
+  public AbfsInstrumentation(URI uri) {
+    UUID fileSystemInstanceId = UUID.randomUUID();
+    registry.tag(REGISTRY_ID,
+        "A unique identifier for the instance",
+        fileSystemInstanceId.toString());
+    registry.tag(METRIC_BUCKET, "Hostname from the FS URL", uri.getHost());
+
+    for (AbfsStatistic stats : STATISTIC_LIST) {
+      createCounter(stats);
+    }
+  }
+
+  /**
+   * Look up a Metric from registered set.
+   *
+   * @param name name of metric.
+   * @return the metric or null.
+   */
+  private MutableMetric lookupMetric(String name) {
+    return getRegistry().get(name);
+  }
+
+  /**
+   * Look up counter by name.
+   *
+   * @param name name of counter.
+   * @return counter if found, else null.
+   */
+  private MutableCounterLong lookupCounter(String name) {
+    MutableMetric metric = lookupMetric(name);
+    if (metric == null) {
+      return null;
+    }
+    if (!(metric instanceof MutableCounterLong)) {
+      throw new IllegalStateException("Metric " + name
+          + " is not a MutableCounterLong: " + metric);
+    }
+    return (MutableCounterLong) metric;
+  }
+
+  /**
+   * Create a counter in the registry.
+   *
+   * @param stats AbfsStatistic whose counter needs to be made.
+   * @return counter or null.
+   */
+  private MutableCounterLong createCounter(AbfsStatistic stats) {
+    return registry.newCounter(stats.getStatName(),
+        stats.getStatDescription(), 0L);
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * Increment a statistic with some value.
+   *
+   * @param statistic AbfsStatistic need to be incremented.
+   * @param value     long value to be incremented by.
+   */
+  @Override
+  public void incrementCounter(AbfsStatistic statistic, long value) {
+    MutableCounterLong counter = lookupCounter(statistic.getStatName());
+    if (counter != null) {
+      counter.incr(value);
+    }
+  }
+
+  /**
+   * Getter for MetricRegistry.
+   *
+   * @return MetricRegistry or null.
+   */
+  private MetricsRegistry getRegistry() {
+    return registry;
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * Method to aggregate all the counters in the MetricRegistry and form a
+   * string with prefix, separator and suffix.
+   *
+   * @param prefix    string that would be before metric.
+   * @param separator string that would be between metric name and value.
+   * @param suffix    string that would be after metric value.
+   * @param all       gets all the values even if unchanged.
+   * @return a String with all the metrics and their values.
+   */
+  @Override
+  public String formString(String prefix, String separator, String suffix,
+      boolean all) {
+
+    MetricStringBuilder metricStringBuilder = new MetricStringBuilder(null,
+        prefix, separator, suffix);
+    registry.snapshot(metricStringBuilder, all);
+    return metricStringBuilder.toString();
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * Creating a map of all the counters for testing.
+   *
+   * @return a map of the metrics.
+   */
+  @VisibleForTesting
+  @Override
+  public Map<String, Long> toMap() {
+    MetricsToMap metricBuilder = new MetricsToMap(null);
+    registry.snapshot(metricBuilder, true);
+    return metricBuilder.getMap();
+  }
+
+  protected static class MetricsToMap extends MetricsRecordBuilder {
+    private final MetricsCollector parent;
+    private final Map<String, Long> map =
+        new HashMap<>();
+
+    MetricsToMap(MetricsCollector parent) {
+      this.parent = parent;
+    }
+
+    @Override
+    public MetricsRecordBuilder tag(MetricsInfo info, String value) {
+      return this;
+    }
+
+    @Override
+    public MetricsRecordBuilder add(MetricsTag tag) {
+      return this;
+    }
+
+    @Override
+    public MetricsRecordBuilder add(AbstractMetric metric) {
+      return this;
+    }
+
+    @Override
+    public MetricsRecordBuilder setContext(String value) {
+      return this;
+    }
+
+    @Override
+    public MetricsRecordBuilder addCounter(MetricsInfo info, int value) {
+      return tuple(info, value);
+    }
+
+    @Override
+    public MetricsRecordBuilder addCounter(MetricsInfo info, long value) {
+      return tuple(info, value);
+    }
+
+    @Override
+    public MetricsRecordBuilder addGauge(MetricsInfo info, int value) {
+      return tuple(info, value);
+    }
+
+    @Override
+    public MetricsRecordBuilder addGauge(MetricsInfo info, long value) {
+      return tuple(info, value);
+    }
+
+    public MetricsToMap tuple(MetricsInfo info, long value) {
+      return tuple(info.name(), value);
+    }
+
+    public MetricsToMap tuple(String name, long value) {
+      map.put(name, value);
+      return this;
+    }
+
+    @Override
+    public MetricsRecordBuilder addGauge(MetricsInfo info, float value) {
+      return tuple(info, (long) value);
+    }
+
+    @Override
+    public MetricsRecordBuilder addGauge(MetricsInfo info, double value) {
+      return tuple(info, (long) value);
+    }
+
+    @Override
+    public MetricsCollector parent() {
+      return parent;
+    }
+
+    /**
+     * Get the map.
+     *
+     * @return the map of metrics.
+     */
+    public Map<String, Long> getMap() {
+      return map;
+    }
+  }
+}

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AbfsStatistic.java

@@ -0,0 +1,93 @@
+/**
+ * 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.fs.azurebfs;
+
+import org.apache.hadoop.fs.StorageStatistics.CommonStatisticNames;
+
+/**
+ * Statistic which are collected in Abfs.
+ * Available as metrics in {@link AbfsInstrumentation}.
+ */
+public enum AbfsStatistic {
+
+  CALL_CREATE(CommonStatisticNames.OP_CREATE,
+      "Calls of create()."),
+  CALL_OPEN(CommonStatisticNames.OP_OPEN,
+      "Calls of open()."),
+  CALL_GET_FILE_STATUS(CommonStatisticNames.OP_GET_FILE_STATUS,
+      "Calls of getFileStatus()."),
+  CALL_APPEND(CommonStatisticNames.OP_APPEND,
+      "Calls of append()."),
+  CALL_CREATE_NON_RECURSIVE(CommonStatisticNames.OP_CREATE_NON_RECURSIVE,
+      "Calls of createNonRecursive()."),
+  CALL_DELETE(CommonStatisticNames.OP_DELETE,
+      "Calls of delete()."),
+  CALL_EXIST(CommonStatisticNames.OP_EXISTS,
+      "Calls of exist()."),
+  CALL_GET_DELEGATION_TOKEN(CommonStatisticNames.OP_GET_DELEGATION_TOKEN,
+      "Calls of getDelegationToken()."),
+  CALL_LIST_STATUS(CommonStatisticNames.OP_LIST_STATUS,
+      "Calls of listStatus()."),
+  CALL_MKDIRS(CommonStatisticNames.OP_MKDIRS,
+      "Calls of mkdirs()."),
+  CALL_RENAME(CommonStatisticNames.OP_RENAME,
+      "Calls of rename()."),
+  DIRECTORIES_CREATED("directories_created",
+      "Total number of directories created through the object store."),
+  DIRECTORIES_DELETED("directories_deleted",
+      "Total number of directories deleted through the object store."),
+  FILES_CREATED("files_created",
+      "Total number of files created through the object store."),
+  FILES_DELETED("files_deleted",
+      "Total number of files deleted from the object store."),
+  ERROR_IGNORED("error_ignored",
+      "Errors caught and ignored.");
+
+  private String statName;
+  private String statDescription;
+
+  /**
+   * Constructor of AbfsStatistic to set statistic name and description.
+   *
+   * @param statName        Name of the statistic.
+   * @param statDescription Description of the statistic.
+   */
+  AbfsStatistic(String statName, String statDescription) {
+    this.statName = statName;
+    this.statDescription = statDescription;
+  }
+
+  /**
+   * Getter for statistic name.
+   *
+   * @return Name of statistic.
+   */
+  public String getStatName() {
+    return statName;
+  }
+
+  /**
+   * Getter for statistic description.
+   *
+   * @return Description of statistic.
+   */
+  public String getStatDescription() {
+    return statDescription;
+  }
+}

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AzureBlobFileSystem.java

@@ -30,6 +30,7 @@
 import java.util.List;
 import java.util.ArrayList;
 import java.util.EnumSet;
+import java.util.Map;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
@@ -68,6 +69,7 @@
 import org.apache.hadoop.fs.azurebfs.contracts.exceptions.SASTokenProviderException;
 import org.apache.hadoop.fs.azurebfs.contracts.services.AzureServiceErrorCode;
 import org.apache.hadoop.fs.azurebfs.security.AbfsDelegationTokenManager;
+import org.apache.hadoop.fs.azurebfs.services.AbfsCounters;
 import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsAction;
@@ -78,6 +80,7 @@
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.util.Progressable;
 
+import static org.apache.hadoop.fs.azurebfs.AbfsStatistic.*;
 import static org.apache.hadoop.fs.impl.PathCapabilitiesSupport.validatePathCapabilityArgs;
 
 /**
@@ -94,6 +97,7 @@ public class AzureBlobFileSystem extends FileSystem {
 
   private boolean delegationTokenEnabled = false;
   private AbfsDelegationTokenManager delegationTokenManager;
+  private AbfsCounters instrumentation;
 
   @Override
   public void initialize(URI uri, Configuration configuration)
@@ -109,7 +113,7 @@ public void initialize(URI uri, Configuration configuration)
     LOG.trace("AzureBlobFileSystemStore init complete");
 
     final AbfsConfiguration abfsConfiguration = abfsStore.getAbfsConfiguration();
-
+    instrumentation = new AbfsInstrumentation(uri);
     this.setWorkingDirectory(this.getHomeDirectory());
 
     if (abfsConfiguration.getCreateRemoteFileSystemDuringInitialization()) {
@@ -146,6 +150,11 @@ public String toString() {
     sb.append("uri=").append(uri);
     sb.append(", user='").append(abfsStore.getUser()).append('\'');
     sb.append(", primaryUserGroup='").append(abfsStore.getPrimaryGroup()).append('\'');
+    if (instrumentation != null) {
+      sb.append(", Statistics: {").append(instrumentation.formString("{", "=",
+          "}", true));
+      sb.append("}");
+    }
     sb.append('}');
     return sb.toString();
   }
@@ -162,7 +171,7 @@ public URI getUri() {
   @Override
   public FSDataInputStream open(final Path path, final int bufferSize) throws IOException {
     LOG.debug("AzureBlobFileSystem.open path: {} bufferSize: {}", path, bufferSize);
-
+    statIncrement(CALL_OPEN);
     Path qualifiedPath = makeQualified(path);
 
     try {
@@ -183,6 +192,7 @@ public FSDataOutputStream create(final Path f, final FsPermission permission, fi
         overwrite,
         blockSize);
 
+    statIncrement(CALL_CREATE);
     trailingPeriodCheck(f);
 
     Path qualifiedPath = makeQualified(f);
@@ -190,6 +200,7 @@ public FSDataOutputStream create(final Path f, final FsPermission permission, fi
     try {
       OutputStream outputStream = abfsStore.createFile(qualifiedPath, statistics, overwrite,
           permission == null ? FsPermission.getFileDefault() : permission, FsPermission.getUMask(getConf()));
+      statIncrement(FILES_CREATED);
       return new FSDataOutputStream(outputStream, statistics);
     } catch(AzureBlobFileSystemException ex) {
       checkException(f, ex);
@@ -203,6 +214,7 @@ public FSDataOutputStream createNonRecursive(final Path f, final FsPermission pe
       final boolean overwrite, final int bufferSize, final short replication, final long blockSize,
       final Progressable progress) throws IOException {
 
+    statIncrement(CALL_CREATE_NON_RECURSIVE);
     final Path parent = f.getParent();
     final FileStatus parentFileStatus = tryGetFileStatus(parent);
 
@@ -246,7 +258,7 @@ public FSDataOutputStream append(final Path f, final int bufferSize, final Progr
         "AzureBlobFileSystem.append path: {} bufferSize: {}",
         f.toString(),
         bufferSize);
-
+    statIncrement(CALL_APPEND);
     Path qualifiedPath = makeQualified(f);
 
     try {
@@ -261,7 +273,7 @@ public FSDataOutputStream append(final Path f, final int bufferSize, final Progr
   public boolean rename(final Path src, final Path dst) throws IOException {
     LOG.debug(
         "AzureBlobFileSystem.rename src: {} dst: {}", src.toString(), dst.toString());
-
+    statIncrement(CALL_RENAME);
     trailingPeriodCheck(dst);
 
     Path parentFolder = src.getParent();
@@ -328,7 +340,7 @@ public boolean rename(final Path src, final Path dst) throws IOException {
   public boolean delete(final Path f, final boolean recursive) throws IOException {
     LOG.debug(
         "AzureBlobFileSystem.delete path: {} recursive: {}", f.toString(), recursive);
-
+    statIncrement(CALL_DELETE);
     Path qualifiedPath = makeQualified(f);
 
     if (f.isRoot()) {
@@ -353,7 +365,7 @@ public boolean delete(final Path f, final boolean recursive) throws IOException
   public FileStatus[] listStatus(final Path f) throws IOException {
     LOG.debug(
         "AzureBlobFileSystem.listStatus path: {}", f.toString());
-
+    statIncrement(CALL_LIST_STATUS);
     Path qualifiedPath = makeQualified(f);
 
     try {
@@ -365,6 +377,24 @@ public FileStatus[] listStatus(final Path f) throws IOException {
     }
   }
 
+  /**
+   * Increment of an Abfs statistic.
+   *
+   * @param statistic AbfsStatistic that needs increment.
+   */
+  private void statIncrement(AbfsStatistic statistic) {
+    incrementStatistic(statistic);
+  }
+
+  /**
+   * Method for incrementing AbfsStatistic by a long value.
+   *
+   * @param statistic the Statistic to be incremented.
+   */
+  private void incrementStatistic(AbfsStatistic statistic) {
+    instrumentation.incrementCounter(statistic, 1);
+  }
+
   /**
    * Performs a check for (.) until root in the path to throw an exception.
    * The purpose is to differentiate between dir/dir1 and dir/dir1.
@@ -394,7 +424,7 @@ private void trailingPeriodCheck(Path path) throws IllegalArgumentException {
   public boolean mkdirs(final Path f, final FsPermission permission) throws IOException {
     LOG.debug(
         "AzureBlobFileSystem.mkdirs path: {} permissions: {}", f, permission);
-
+    statIncrement(CALL_MKDIRS);
     trailingPeriodCheck(f);
 
     final Path parentFolder = f.getParent();
@@ -408,6 +438,7 @@ public boolean mkdirs(final Path f, final FsPermission permission) throws IOExce
     try {
       abfsStore.createDirectory(qualifiedPath, permission == null ? FsPermission.getDirDefault() : permission,
           FsPermission.getUMask(getConf()));
+      statIncrement(DIRECTORIES_CREATED);
       return true;
     } catch (AzureBlobFileSystemException ex) {
       checkException(f, ex, AzureServiceErrorCode.PATH_ALREADY_EXISTS);
@@ -425,12 +456,13 @@ public synchronized void close() throws IOException {
     LOG.debug("AzureBlobFileSystem.close");
     IOUtils.cleanupWithLogger(LOG, abfsStore, delegationTokenManager);
     this.isClosed = true;
+    LOG.debug("Closing Abfs: " + toString());
   }
 
   @Override
   public FileStatus getFileStatus(final Path f) throws IOException {
     LOG.debug("AzureBlobFileSystem.getFileStatus path: {}", f);
-
+    statIncrement(CALL_GET_FILE_STATUS);
     Path qualifiedPath = makeQualified(f);
 
     try {
@@ -567,6 +599,11 @@ private boolean deleteRoot() throws IOException {
           @Override
           public Void call() throws Exception {
             delete(fs.getPath(), fs.isDirectory());
+            if (fs.isDirectory()) {
+              statIncrement(DIRECTORIES_DELETED);
+            } else {
+              statIncrement(FILES_DELETED);
+            }
             return null;
           }
         });
@@ -930,11 +967,25 @@ public void access(final Path path, final FsAction mode) throws IOException {
     }
   }
 
+  /**
+   * Incrementing exists() calls from superclass for statistic collection.
+   *
+   * @param f source path.
+   * @return true if the path exists.
+   * @throws IOException
+   */
+  @Override
+  public boolean exists(Path f) throws IOException {
+    statIncrement(CALL_EXIST);
+    return super.exists(f);
+  }
+
   private FileStatus tryGetFileStatus(final Path f) {
     try {
       return getFileStatus(f);
     } catch (IOException ex) {
       LOG.debug("File not found {}", f);
+      statIncrement(ERROR_IGNORED);
       return null;
     }
   }
@@ -951,6 +1002,7 @@ private boolean fileSystemExists() throws IOException {
         // there is not way to get the storage error code
         // workaround here is to check its status code.
       } catch (FileNotFoundException e) {
+        statIncrement(ERROR_IGNORED);
         return false;
       }
     }
@@ -1124,6 +1176,7 @@ private Throwable getRootCause(Throwable throwable) {
    */
   @Override
   public synchronized Token<?> getDelegationToken(final String renewer) throws IOException {
+    statIncrement(CALL_GET_DELEGATION_TOKEN);
     return this.delegationTokenEnabled ? this.delegationTokenManager.getDelegationToken(renewer)
         : super.getDelegationToken(renewer);
   }
@@ -1186,6 +1239,11 @@ boolean getIsNamespaceEnabled() throws AzureBlobFileSystemException {
     return abfsStore.getIsNamespaceEnabled();
   }
 
+  @VisibleForTesting
+  Map<String, Long> getInstrumentationMap() {
+    return instrumentation.toMap();
+  }
+
   @Override
   public boolean hasPathCapability(final Path path, final String capability)
       throws IOException {

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/AbfsCounters.java

@@ -0,0 +1,66 @@
+/**
+ * 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.fs.azurebfs.services;
+
+import java.util.Map;
+
+import com.google.common.annotations.VisibleForTesting;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.azurebfs.AbfsStatistic;
+
+/**
+ * An interface for Abfs counters.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+public interface AbfsCounters {
+
+  /**
+   * Increment a AbfsStatistic by a long value.
+   *
+   * @param statistic AbfsStatistic to be incremented.
+   * @param value     the value to increment the statistic by.
+   */
+  void incrementCounter(AbfsStatistic statistic, long value);
+
+  /**
+   * Form a String of the all the statistics and present in an organized manner.
+   *
+   * @param prefix    the prefix to be set.
+   * @param separator the separator between the statistic name and value.
+   * @param suffix    the suffix to be used.
+   * @param all       enable all the statistics to be displayed or not.
+   * @return String of all the statistics and their values.
+   */
+  String formString(String prefix, String separator, String suffix,
+      boolean all);
+
+  /**
+   * Convert all the statistics into a key-value pair map to be used for
+   * testing.
+   *
+   * @return map with statistic name as key and statistic value as the map
+   * value.
+   */
+  @VisibleForTesting
+  Map<String, Long> toMap();
+
+}

hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/AbstractAbfsIntegrationTest.java

@@ -21,6 +21,7 @@
 import java.io.IOException;
 import java.net.URI;
 import java.util.Hashtable;
+import java.util.Map;
 import java.util.UUID;
 import java.util.concurrent.Callable;
 
@@ -426,4 +427,18 @@ protected AbfsOutputStream createAbfsOutputStreamWithFlushEnabled(
     return (AbfsOutputStream) abfss.createFile(path, fs.getFsStatistics(),
         true, FsPermission.getDefault(), FsPermission.getUMask(fs.getConf()));
   }
+
+  /**
+   * Custom assertion for AbfsStatistics which have statistics, expected
+   * value and map of statistics and value as its parameters.
+   * @param statistic the AbfsStatistics which needs to be asserted.
+   * @param expectedValue the expected value of the statistics.
+   * @param metricMap map of (String, Long) with statistics name as key and
+   *                  statistics value as map value.
+   */
+  protected void assertAbfsStatistics(AbfsStatistic statistic,
+      long expectedValue, Map<String, Long> metricMap) {
+    assertEquals("Mismatch in " + statistic.getStatName(), expectedValue,
+        (long) metricMap.get(statistic.getStatName()));
+  }
 }

hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/ITestAbfsStatistics.java

@@ -0,0 +1,258 @@
+/**
+ * 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.fs.azurebfs;
+
+import java.io.IOException;
+import java.util.Map;
+
+import org.junit.Test;
+
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.azurebfs.services.AbfsCounters;
+import org.apache.hadoop.fs.permission.FsPermission;
+
+/**
+ * Tests AzureBlobFileSystem Statistics.
+ */
+public class ITestAbfsStatistics extends AbstractAbfsIntegrationTest {
+
+  private static final int NUMBER_OF_OPS = 10;
+
+  public ITestAbfsStatistics() throws Exception {
+  }
+
+  /**
+   * Testing the initial value of statistics.
+   */
+  @Test
+  public void testInitialStatsValues() throws IOException {
+    describe("Testing the initial values of Abfs counters");
+
+    AbfsCounters abfsCounters =
+        new AbfsInstrumentation(getFileSystem().getUri());
+    Map<String, Long> metricMap = abfsCounters.toMap();
+
+    for (Map.Entry<String, Long> entry : metricMap.entrySet()) {
+      String key = entry.getKey();
+      Long value = entry.getValue();
+
+      //Verify if initial value of statistic is 0.
+      checkInitialValue(key, value);
+    }
+  }
+
+  /**
+   * Testing statistics by creating files and directories.
+   */
+  @Test
+  public void testCreateStatistics() throws IOException {
+    describe("Testing counter values got by creating directories and files in"
+        + " Abfs");
+
+    AzureBlobFileSystem fs = getFileSystem();
+    Path createFilePath = path(getMethodName());
+    Path createDirectoryPath = path(getMethodName() + "Dir");
+
+    fs.mkdirs(createDirectoryPath);
+    fs.createNonRecursive(createFilePath, FsPermission
+        .getDefault(), false, 1024, (short) 1, 1024, null);
+
+    Map<String, Long> metricMap = fs.getInstrumentationMap();
+    /*
+    Test of statistic values after creating a directory and a file ;
+    getFileStatus is called 1 time after creating file and 1 time at time of
+    initialising.
+     */
+    assertAbfsStatistics(AbfsStatistic.CALL_CREATE, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_CREATE_NON_RECURSIVE, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.FILES_CREATED, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.DIRECTORIES_CREATED, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_MKDIRS, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_GET_FILE_STATUS, 2, metricMap);
+
+    //re-initialising Abfs to reset statistic values.
+    fs.initialize(fs.getUri(), fs.getConf());
+
+    /*
+    Creating 10 directories and files; Directories and files can't be created
+    with same name, hence <Name> + i to give unique names.
+     */
+    for (int i = 0; i < NUMBER_OF_OPS; i++) {
+      fs.mkdirs(path(getMethodName() + "Dir" + i));
+      fs.createNonRecursive(path(getMethodName() + i),
+          FsPermission.getDefault(), false, 1024, (short) 1,
+          1024, null);
+    }
+
+    metricMap = fs.getInstrumentationMap();
+    /*
+    Test of statistics values after creating 10 directories and files;
+    getFileStatus is called 1 time at initialise() plus number of times file
+    is created.
+     */
+    assertAbfsStatistics(AbfsStatistic.CALL_CREATE, NUMBER_OF_OPS, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_CREATE_NON_RECURSIVE, NUMBER_OF_OPS,
+        metricMap);
+    assertAbfsStatistics(AbfsStatistic.FILES_CREATED, NUMBER_OF_OPS, metricMap);
+    assertAbfsStatistics(AbfsStatistic.DIRECTORIES_CREATED, NUMBER_OF_OPS,
+        metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_MKDIRS, NUMBER_OF_OPS, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_GET_FILE_STATUS,
+        1 + NUMBER_OF_OPS, metricMap);
+  }
+
+  /**
+   * Testing statistics by deleting files and directories.
+   */
+  @Test
+  public void testDeleteStatistics() throws IOException {
+    describe("Testing counter values got by deleting directory and files "
+        + "in Abfs");
+
+    AzureBlobFileSystem fs = getFileSystem();
+    /*
+    This directory path needs to be root for triggering the
+    directories_deleted counter.
+     */
+    Path createDirectoryPath = path("/");
+    Path createFilePath = path(getMethodName());
+
+    /*
+    creating a directory and a file inside that directory.
+    The directory is root. Hence, no parent. This allows us to invoke
+    deleteRoot() method to see the population of directories_deleted and
+    files_deleted counters.
+     */
+    fs.mkdirs(createDirectoryPath);
+    fs.create(path(createDirectoryPath + getMethodName()));
+    fs.delete(createDirectoryPath, true);
+
+    Map<String, Long> metricMap = fs.getInstrumentationMap();
+
+    /*
+    Test for op_delete, files_deleted, op_list_status.
+    since directory is delete recursively op_delete is called 2 times.
+    1 file is deleted, 1 listStatus() call is made.
+     */
+    assertAbfsStatistics(AbfsStatistic.CALL_DELETE, 2, metricMap);
+    assertAbfsStatistics(AbfsStatistic.FILES_DELETED, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_LIST_STATUS, 1, metricMap);
+
+    /*
+    creating a root directory and deleting it recursively to see if
+    directories_deleted is called or not.
+     */
+    fs.mkdirs(createDirectoryPath);
+    fs.create(createFilePath);
+    fs.delete(createDirectoryPath, true);
+    metricMap = fs.getInstrumentationMap();
+
+    //Test for directories_deleted.
+    assertAbfsStatistics(AbfsStatistic.DIRECTORIES_DELETED, 1, metricMap);
+  }
+
+  /**
+   * Testing statistics of open, append, rename and exists method calls.
+   */
+  @Test
+  public void testOpenAppendRenameExists() throws IOException {
+    describe("Testing counter values on calling open, append and rename and "
+        + "exists methods on Abfs");
+
+    AzureBlobFileSystem fs = getFileSystem();
+    Path createFilePath = path(getMethodName());
+    Path destCreateFilePath = path(getMethodName() + "New");
+
+    fs.create(createFilePath);
+    fs.open(createFilePath);
+    fs.append(createFilePath);
+    assertTrue(fs.rename(createFilePath, destCreateFilePath));
+
+    Map<String, Long> metricMap = fs.getInstrumentationMap();
+    //Testing single method calls to open, append and rename.
+    assertAbfsStatistics(AbfsStatistic.CALL_OPEN, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_APPEND, 1, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_RENAME, 1, metricMap);
+
+    //Testing if file exists at path.
+    assertTrue(String.format("File with name %s should exist",
+        destCreateFilePath),
+        fs.exists(destCreateFilePath));
+    assertFalse(String.format("File with name %s should not exist",
+        createFilePath),
+        fs.exists(createFilePath));
+
+    metricMap = fs.getInstrumentationMap();
+    //Testing exists() calls.
+    assertAbfsStatistics(AbfsStatistic.CALL_EXIST, 2, metricMap);
+
+    //re-initialising Abfs to reset statistic values.
+    fs.initialize(fs.getUri(), fs.getConf());
+
+    fs.create(destCreateFilePath);
+
+    for (int i = 0; i < NUMBER_OF_OPS; i++) {
+      fs.open(destCreateFilePath);
+      fs.append(destCreateFilePath);
+    }
+
+    metricMap = fs.getInstrumentationMap();
+
+    //Testing large number of method calls to open, append.
+    assertAbfsStatistics(AbfsStatistic.CALL_OPEN, NUMBER_OF_OPS, metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_APPEND, NUMBER_OF_OPS, metricMap);
+
+    for (int i = 0; i < NUMBER_OF_OPS; i++) {
+      // rename and then back to earlier name for no error while looping.
+      assertTrue(fs.rename(destCreateFilePath, createFilePath));
+      assertTrue(fs.rename(createFilePath, destCreateFilePath));
+
+      //check if first name is existing and 2nd is not existing.
+      assertTrue(String.format("File with name %s should exist",
+          destCreateFilePath),
+          fs.exists(destCreateFilePath));
+      assertFalse(String.format("File with name %s should not exist",
+          createFilePath),
+          fs.exists(createFilePath));
+
+    }
+
+    metricMap = fs.getInstrumentationMap();
+
+    /*
+    Testing exists() calls and rename calls. Since both were called 2
+    times in 1 loop. 2*numberOfOps is expectedValue.
+    */
+    assertAbfsStatistics(AbfsStatistic.CALL_RENAME, 2 * NUMBER_OF_OPS,
+        metricMap);
+    assertAbfsStatistics(AbfsStatistic.CALL_EXIST, 2 * NUMBER_OF_OPS,
+        metricMap);
+
+  }
+
+  /**
+   * Method to check initial value of the statistics which should be 0.
+   *
+   * @param statName  name of the statistic to be checked.
+   * @param statValue value of the statistic.
+   */
+  private void checkInitialValue(String statName, long statValue) {
+    assertEquals("Mismatch in " + statName, 0, statValue);
+  }
+}

hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/TestAbfsStatistics.java

@@ -0,0 +1,61 @@
+/**
+ * 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.fs.azurebfs;
+
+import java.io.IOException;
+import java.util.Map;
+
+import org.junit.Test;
+
+import org.apache.hadoop.fs.azurebfs.services.AbfsCounters;
+
+/**
+ * Unit tests for Abfs common counters.
+ */
+public class TestAbfsStatistics extends AbstractAbfsIntegrationTest {
+
+  private static final int LARGE_OPS = 100;
+
+  public TestAbfsStatistics() throws Exception {
+  }
+
+  /**
+   * Tests for op_get_delegation_token and error_ignore counter values.
+   */
+  @Test
+  public void testInitializeStats() throws IOException {
+    describe("Testing the counter values after Abfs is initialised");
+
+    AbfsCounters instrumentation =
+        new AbfsInstrumentation(getFileSystem().getUri());
+
+    //Testing summation of the counter values.
+    for (int i = 0; i < LARGE_OPS; i++) {
+      instrumentation.incrementCounter(AbfsStatistic.CALL_GET_DELEGATION_TOKEN, 1);
+      instrumentation.incrementCounter(AbfsStatistic.ERROR_IGNORED, 1);
+    }
+
+    Map<String, Long> metricMap = instrumentation.toMap();
+
+    assertAbfsStatistics(AbfsStatistic.CALL_GET_DELEGATION_TOKEN, LARGE_OPS,
+        metricMap);
+    assertAbfsStatistics(AbfsStatistic.ERROR_IGNORED, LARGE_OPS, metricMap);
+
+  }
+}