Issue #5352 minor refactoring is performed, Javadoc is added.

core/src/main/java/com/orientechnologies/orient/core/index/hashindex/local/OHashTableDirectory.java

@@ -699,9 +699,4 @@ private int getLocalNodeIndex(int nodeIndex) {
 
     return (nodeIndex - ODirectoryFirstPage.NODES_PER_PAGE) % ODirectoryPage.NODES_PER_PAGE;
   }
-
-  @Override
-  protected OAtomicOperation startAtomicOperation(boolean trackNonTxOperations) throws IOException {
-    return atomicOperationsManager.startAtomicOperation(this, trackNonTxOperations);
-  }
 }

core/src/main/java/com/orientechnologies/orient/core/index/hashindex/local/OLocalHashTable.java

@@ -198,11 +198,6 @@ public void create(OBinarySerializer<K> keySerializer, OBinarySerializer<V> valu
     }
   }
 
-  @Override
-  protected OAtomicOperation startAtomicOperation(boolean trackNonTxOperations) throws IOException {
-    return atomicOperationsManager.startAtomicOperation(this, trackNonTxOperations);
-  }
-
   @Override
   public OBinarySerializer<K> getKeySerializer() {
     acquireSharedLock();

core/src/main/java/com/orientechnologies/orient/core/index/hashindex/local/OLocalHashTable20.java

@@ -207,11 +207,6 @@ public void create(OBinarySerializer<K> keySerializer, OBinarySerializer<V> valu
     }
   }
 
-  @Override
-  protected OAtomicOperation startAtomicOperation(boolean trackNonTxOperations) throws IOException {
-    return atomicOperationsManager.startAtomicOperation(this, trackNonTxOperations);
-  }
-
   @Override
   public OBinarySerializer<K> getKeySerializer() {
     acquireSharedLock();

core/src/main/java/com/orientechnologies/orient/core/index/sbtree/local/OSBTree.java

@@ -872,11 +872,6 @@ public void flush() {
     }
   }
 
-  @Override
-  protected OAtomicOperation startAtomicOperation(boolean trackNonTxOperations) throws IOException {
-    return atomicOperationsManager.startAtomicOperation(this, trackNonTxOperations);
-  }
-
   private void checkNullSupport(K key) {
     if (key == null && !nullPointerSupport)
       throw new OSBTreeException("Null keys are not supported.", this);

core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/paginated/OClusterPositionMap.java

@@ -615,9 +615,4 @@ public long getLastPosition() throws IOException {
       completeOperation();
     }
   }
-
-  @Override
-  protected OAtomicOperation startAtomicOperation(boolean trackNonTxOperations) throws IOException {
-    return atomicOperationsManager.startAtomicOperation(this, trackNonTxOperations);
-  }
 }

core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/paginated/OPaginatedCluster.java

@@ -1466,11 +1466,6 @@ private void setRecordConflictStrategy(final String stringValue) {
     storageLocal.getConfiguration().update();
   }
 
-  @Override
-  protected OAtomicOperation startAtomicOperation(boolean trackNonTxOperations) throws IOException {
-    return atomicOperationsManager.startAtomicOperation(this, trackNonTxOperations);
-  }
-
   private void updateClusterState(long sizeDiff, long recordsSizeDiff, OAtomicOperation atomicOperation) throws IOException {
     final OCacheEntry pinnedStateEntry = loadPage(atomicOperation, fileId, pinnedStateEntryIndex, true);
     pinnedStateEntry.acquireExclusiveLock();

core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/paginated/atomicoperations/OAtomicOperationsManager.java

@@ -116,6 +116,9 @@ public OAtomicOperationsManager(OAbstractPaginatedStorage storage) {
     this.storagePerformanceStatistic = storage.getStoragePerformanceStatistic();
   }
 
+  /**
+   * @see #startAtomicOperation(String, boolean)
+   */
   public OAtomicOperation startAtomicOperation(ODurableComponent durableComponent, boolean trackNonTxOperations)
       throws IOException {
     if (durableComponent != null)
@@ -124,6 +127,27 @@ public OAtomicOperation startAtomicOperation(ODurableComponent durableComponent,
     return startAtomicOperation((String) null, trackNonTxOperations);
   }
 
+  /**
+   * Starts atomic operation inside of current thread.
+   * If atomic operation has been already started , current atomic operation instance will be returned.
+   * All durable components have to call this method at the beginning of any data modification operation.
+   * <p>
+   * In current implementation of atomic operation, each component which is participated in atomic operation is hold under exclusive
+   * lock till atomic operation will not be completed (committed or rollbacked).
+   * <p>
+   * If other thread is going to read data from component it has to acquire read lock inside of atomic operation manager {@link #acquireReadLock(ODurableComponent)}
+   * , otherwise data consistency will be compromised.
+   * <p>
+   * Atomic operation may be delayed if start of atomic operations is prohibited by call of {@link #freezeAtomicOperations(Class, String)}
+   * method. If mentioned above method is called then execution of current method will be stopped till call of {@link #releaseAtomicOperations(long)}
+   * method or exception will be thrown. Concrete behaviour depends on real values of parameters of {@link #freezeAtomicOperations(Class, String)} method.
+   *
+   * @param trackNonTxOperations If this flag set to <code>true</code> then special record {@link ONonTxOperationPerformedWALRecord} will be added to
+   *                             WAL in case of atomic operation is started outside of active storage transaction. During storage restore procedure
+   *                             this record is monitored and if given record is present then rebuild of all indexes is performed.
+   * @param fullName             Name of component which is going participate in atomic operation.
+   * @return Instance of active atomic operation.
+   */
   public OAtomicOperation startAtomicOperation(String fullName, boolean trackNonTxOperations) throws IOException {
     if (writeAheadLog == null)
       return null;

core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/paginated/base/ODurableComponent.java

@@ -111,6 +111,9 @@ protected void endAtomicOperation(boolean rollback, Exception e) throws IOExcept
     atomicOperationsManager.endAtomicOperation(rollback, e);
   }
 
+  /**
+   * @see OAtomicOperationsManager#startAtomicOperation(com.orientechnologies.orient.core.storage.impl.local.paginated.base.ODurableComponent, boolean)
+   */
   protected OAtomicOperation startAtomicOperation(boolean trackNonTxOperations) throws IOException {
     return atomicOperationsManager.startAtomicOperation(this, trackNonTxOperations);
   }