HDDS-1986. Fix listkeys API. (#1588)

Author: bharatviswa504

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OmMetadataManagerImpl.java

@@ -23,6 +23,9 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.TreeSet;
 import java.util.stream.Collectors;
 
 import org.apache.hadoop.hdds.client.BlockID;
@@ -653,7 +656,12 @@ public List<OmBucketInfo> listBuckets(final String volumeName,
   @Override
   public List<OmKeyInfo> listKeys(String volumeName, String bucketName,
       String startKey, String keyPrefix, int maxKeys) throws IOException {
+
     List<OmKeyInfo> result = new ArrayList<>();
+    if (maxKeys <= 0) {
+      return result;
+    }
+
     if (Strings.isNullOrEmpty(volumeName)) {
       throw new OMException("Volume name is required.",
           ResultCodes.VOLUME_NOT_FOUND);
@@ -688,26 +696,85 @@ public List<OmKeyInfo> listKeys(String volumeName, String bucketName,
       seekPrefix = getBucketKey(volumeName, bucketName + OM_KEY_PREFIX);
     }
     int currentCount = 0;
-    try (TableIterator<String, ? extends KeyValue<String, OmKeyInfo>> keyIter =
-        getKeyTable()
-            .iterator()) {
-      KeyValue<String, OmKeyInfo> kv = keyIter.seek(seekKey);
-      while (currentCount < maxKeys && keyIter.hasNext()) {
-        kv = keyIter.next();
-        // Skip the Start key if needed.
-        if (kv != null && skipStartKey && kv.getKey().equals(seekKey)) {
-          continue;
+
+
+    TreeMap<String, OmKeyInfo> cacheKeyMap = new TreeMap<>();
+    Set<String> deletedKeySet = new TreeSet<>();
+    Iterator<Map.Entry<CacheKey<String>, CacheValue<OmKeyInfo>>> iterator =
+        keyTable.cacheIterator();
+
+    //TODO: We can avoid this iteration if table cache has stored entries in
+    // treemap. Currently HashMap is used in Cache. HashMap get operation is an
+    // constant time operation, where as for treeMap get is log(n).
+    // So if we move to treemap, the get operation will be affected. As get
+    // is frequent operation on table. So, for now in list we iterate cache map
+    // and construct treeMap which match with keyPrefix and are greater than or
+    // equal to startKey. Later we can revisit this, if list operation
+    // is becoming slow.
+    while (iterator.hasNext()) {
+      Map.Entry< CacheKey<String>, CacheValue<OmKeyInfo>> entry =
+          iterator.next();
+
+      String key = entry.getKey().getCacheKey();
+      OmKeyInfo omKeyInfo = entry.getValue().getCacheValue();
+      // Making sure that entry in cache is not for delete key request.
+
+      if (omKeyInfo != null) {
+        if (key.startsWith(seekPrefix) && key.compareTo(seekKey) >= 0) {
+          cacheKeyMap.put(key, omKeyInfo);
         }
+      } else {
+        deletedKeySet.add(key);
+      }
+    }
+
+    // Get maxKeys from DB if it has.
+
+    try (TableIterator<String, ? extends KeyValue<String, OmKeyInfo>>
+             keyIter = getKeyTable().iterator()) {
+      KeyValue< String, OmKeyInfo > kv;
+      keyIter.seek(seekKey);
+      // we need to iterate maxKeys + 1 here because if skipStartKey is true,
+      // we should skip that entry and return the result.
+      while (currentCount < maxKeys + 1 && keyIter.hasNext()) {
+        kv = keyIter.next();
         if (kv != null && kv.getKey().startsWith(seekPrefix)) {
-          result.add(kv.getValue());
-          currentCount++;
+
+          // Entry should not be marked for delete, consider only those
+          // entries.
+          if(!deletedKeySet.contains(kv.getKey())) {
+            cacheKeyMap.put(kv.getKey(), kv.getValue());
+            currentCount++;
+          }
         } else {
           // The SeekPrefix does not match any more, we can break out of the
           // loop.
           break;
         }
       }
     }
+
+    // Finally DB entries and cache entries are merged, then return the count
+    // of maxKeys from the sorted map.
+    currentCount = 0;
+
+    for (Map.Entry<String, OmKeyInfo>  cacheKey : cacheKeyMap.entrySet()) {
+      if (cacheKey.getKey().equals(seekKey) && skipStartKey) {
+        continue;
+      }
+
+      result.add(cacheKey.getValue());
+      currentCount++;
+
+      if (currentCount == maxKeys) {
+        break;
+      }
+    }
+
+    // Clear map and set.
+    cacheKeyMap.clear();
+    deletedKeySet.clear();
+
     return result;
   }
 

hadoop-ozone/ozone-manager/src/test/java/org/apache/hadoop/ozone/om/TestOmMetadataManager.java

@@ -19,9 +19,11 @@
 import com.google.common.base.Optional;
 import org.apache.hadoop.hdds.conf.OzoneConfiguration;
 import org.apache.hadoop.hdds.protocol.StorageType;
+import org.apache.hadoop.hdds.protocol.proto.HddsProtos;
 import org.apache.hadoop.hdds.utils.db.cache.CacheKey;
 import org.apache.hadoop.hdds.utils.db.cache.CacheValue;
 import org.apache.hadoop.ozone.om.helpers.OmBucketInfo;
+import org.apache.hadoop.ozone.om.helpers.OmKeyInfo;
 import org.apache.hadoop.ozone.om.request.TestOMRequestUtils;
 import org.junit.Assert;
 import org.junit.Before;
@@ -188,4 +190,228 @@ private void addBucketsToCache(String volumeName, String bucketName) {
         new CacheValue<>(Optional.of(omBucketInfo), 1));
   }
 
+  @Test
+  public void testListKeys() throws Exception {
+
+    String volumeNameA = "volumeA";
+    String volumeNameB = "volumeB";
+    String ozoneBucket = "ozoneBucket";
+    String hadoopBucket = "hadoopBucket";
+
+
+    // Create volumes and buckets.
+    TestOMRequestUtils.addVolumeToDB(volumeNameA, omMetadataManager);
+    TestOMRequestUtils.addVolumeToDB(volumeNameB, omMetadataManager);
+    addBucketsToCache(volumeNameA, ozoneBucket);
+    addBucketsToCache(volumeNameB, hadoopBucket);
+
+
+    String prefixKeyA = "key-a";
+    String prefixKeyB = "key-b";
+    TreeSet<String> keysASet = new TreeSet<>();
+    TreeSet<String> keysBSet = new TreeSet<>();
+    for (int i=1; i<= 100; i++) {
+      if (i % 2 == 0) {
+        keysASet.add(
+            prefixKeyA + i);
+        addKeysToOM(volumeNameA, ozoneBucket, prefixKeyA + i, i);
+      } else {
+        keysBSet.add(
+            prefixKeyB + i);
+        addKeysToOM(volumeNameA, hadoopBucket, prefixKeyB + i, i);
+      }
+    }
+
+
+    TreeSet<String> keysAVolumeBSet = new TreeSet<>();
+    TreeSet<String> keysBVolumeBSet = new TreeSet<>();
+    for (int i=1; i<= 100; i++) {
+      if (i % 2 == 0) {
+        keysAVolumeBSet.add(
+            prefixKeyA + i);
+        addKeysToOM(volumeNameB, ozoneBucket, prefixKeyA + i, i);
+      } else {
+        keysBVolumeBSet.add(
+            prefixKeyB + i);
+        addKeysToOM(volumeNameB, hadoopBucket, prefixKeyB + i, i);
+      }
+    }
+
+
+    // List all keys which have prefix "key-a"
+    List<OmKeyInfo> omKeyInfoList =
+        omMetadataManager.listKeys(volumeNameA, ozoneBucket,
+            null, prefixKeyA, 100);
+
+    Assert.assertEquals(omKeyInfoList.size(),  50);
+
+    for (OmKeyInfo omKeyInfo : omKeyInfoList) {
+      Assert.assertTrue(omKeyInfo.getKeyName().startsWith(
+          prefixKeyA));
+    }
+
+
+    String startKey = prefixKeyA + 10;
+    omKeyInfoList =
+        omMetadataManager.listKeys(volumeNameA, ozoneBucket,
+            startKey, prefixKeyA, 100);
+
+    Assert.assertEquals(keysASet.tailSet(
+        startKey).size() - 1, omKeyInfoList.size());
+
+    startKey = prefixKeyA + 38;
+    omKeyInfoList =
+        omMetadataManager.listKeys(volumeNameA, ozoneBucket,
+            startKey, prefixKeyA, 100);
+
+    Assert.assertEquals(keysASet.tailSet(
+        startKey).size() - 1, omKeyInfoList.size());
+
+    for (OmKeyInfo omKeyInfo : omKeyInfoList) {
+      Assert.assertTrue(omKeyInfo.getKeyName().startsWith(
+          prefixKeyA));
+      Assert.assertFalse(omKeyInfo.getBucketName().equals(
+          prefixKeyA + 38));
+    }
+
+
+
+    omKeyInfoList = omMetadataManager.listKeys(volumeNameB, hadoopBucket,
+        null, prefixKeyB, 100);
+
+    Assert.assertEquals(omKeyInfoList.size(),  50);
+
+    for (OmKeyInfo omKeyInfo : omKeyInfoList) {
+      Assert.assertTrue(omKeyInfo.getKeyName().startsWith(
+          prefixKeyB));
+    }
+
+    // Try to get keys by count 10, like that get all keys in the
+    // volumeB/ozoneBucket with "key-a".
+    startKey = null;
+    TreeSet<String> expectedKeys = new TreeSet<>();
+    for (int i=0; i<5; i++) {
+
+      omKeyInfoList = omMetadataManager.listKeys(volumeNameB, hadoopBucket,
+          startKey, prefixKeyB, 10);
+
+      Assert.assertEquals(10, omKeyInfoList.size());
+
+      for (OmKeyInfo omKeyInfo : omKeyInfoList) {
+        expectedKeys.add(omKeyInfo.getKeyName());
+        Assert.assertTrue(omKeyInfo.getKeyName().startsWith(
+            prefixKeyB));
+        startKey =  omKeyInfo.getKeyName();
+      }
+    }
+
+    Assert.assertEquals(expectedKeys, keysBVolumeBSet);
+
+
+    // As now we have iterated all 50 buckets, calling next time should
+    // return empty list.
+    omKeyInfoList = omMetadataManager.listKeys(volumeNameB, hadoopBucket,
+        startKey, prefixKeyB, 10);
+
+    Assert.assertEquals(omKeyInfoList.size(), 0);
+
+  }
+
+  @Test
+  public void testListKeysWithFewDeleteEntriesInCache() throws Exception {
+    String volumeNameA = "volumeA";
+    String ozoneBucket = "ozoneBucket";
+
+    // Create volumes and bucket.
+    TestOMRequestUtils.addVolumeToDB(volumeNameA, omMetadataManager);
+
+    addBucketsToCache(volumeNameA, ozoneBucket);
+
+    String prefixKeyA = "key-a";
+    TreeSet<String> keysASet = new TreeSet<>();
+    TreeSet<String> deleteKeySet = new TreeSet<>();
+
+
+    for (int i=1; i<= 100; i++) {
+      if (i % 2 == 0) {
+        keysASet.add(
+            prefixKeyA + i);
+        addKeysToOM(volumeNameA, ozoneBucket, prefixKeyA + i, i);
+      } else {
+        addKeysToOM(volumeNameA, ozoneBucket, prefixKeyA + i, i);
+        String key = omMetadataManager.getOzoneKey(volumeNameA,
+            ozoneBucket, prefixKeyA + i);
+        // Mark as deleted in cache.
+        omMetadataManager.getKeyTable().addCacheEntry(
+            new CacheKey<>(key),
+            new CacheValue<>(Optional.absent(), 100L));
+        deleteKeySet.add(key);
+      }
+    }
+
+    // Now list keys which match with prefixKeyA.
+    List<OmKeyInfo> omKeyInfoList =
+        omMetadataManager.listKeys(volumeNameA, ozoneBucket,
+            null, prefixKeyA, 100);
+
+    // As in total 100, 50 are marked for delete. It should list only 50 keys.
+    Assert.assertEquals(50, omKeyInfoList.size());
+
+    TreeSet<String> expectedKeys = new TreeSet<>();
+
+    for (OmKeyInfo omKeyInfo : omKeyInfoList) {
+      expectedKeys.add(omKeyInfo.getKeyName());
+      Assert.assertTrue(omKeyInfo.getKeyName().startsWith(prefixKeyA));
+    }
+
+    Assert.assertEquals(expectedKeys, keysASet);
+
+
+    // Now get key count by 10.
+    String startKey = null;
+    expectedKeys = new TreeSet<>();
+    for (int i=0; i<5; i++) {
+
+      omKeyInfoList = omMetadataManager.listKeys(volumeNameA, ozoneBucket,
+          startKey, prefixKeyA, 10);
+
+      System.out.println(i);
+      Assert.assertEquals(10, omKeyInfoList.size());
+
+      for (OmKeyInfo omKeyInfo : omKeyInfoList) {
+        expectedKeys.add(omKeyInfo.getKeyName());
+        Assert.assertTrue(omKeyInfo.getKeyName().startsWith(
+            prefixKeyA));
+        startKey =  omKeyInfo.getKeyName();
+      }
+    }
+
+    Assert.assertEquals(keysASet, expectedKeys);
+
+
+    // As now we have iterated all 50 buckets, calling next time should
+    // return empty list.
+    omKeyInfoList = omMetadataManager.listKeys(volumeNameA, ozoneBucket,
+        startKey, prefixKeyA, 10);
+
+    Assert.assertEquals(omKeyInfoList.size(), 0);
+
+
+
+  }
+
+  private void addKeysToOM(String volumeName, String bucketName,
+      String keyName, int i) throws Exception {
+
+    if (i%2== 0) {
+      TestOMRequestUtils.addKeyToTable(false, volumeName, bucketName, keyName,
+          1000L, HddsProtos.ReplicationType.RATIS,
+          HddsProtos.ReplicationFactor.ONE, omMetadataManager);
+    } else {
+      TestOMRequestUtils.addKeyToTableCache(volumeName, bucketName, keyName,
+          HddsProtos.ReplicationType.RATIS, HddsProtos.ReplicationFactor.ONE,
+          omMetadataManager);
+    }
+  }
+
 }