@Override
public void create(final Entity entity) throws EntityStorageException {
    requireNonNull(entity);

    try {
        final boolean hasDuplicate = detectDuplicates(entity);

        if (!hasDuplicate) {
            mongo.getDatabase(ryaInstanceName)
                .getCollection(COLLECTION_NAME)
                .insertOne( ENTITY_CONVERTER.toDocument(entity) );
        } else {
            throw new EntityNearDuplicateException("Duplicate data found and will not be inserted for Entity with Subject: "  + entity);
        }
    } catch(final MongoException e) {
        final ErrorCategory category = ErrorCategory.fromErrorCode( e.getCode() );
        if(category == ErrorCategory.DUPLICATE_KEY) {
            throw new EntityAlreadyExistsException("Failed to create Entity with Subject '" + entity.getSubject().getData() + "'.", e);
        }
        throw new EntityStorageException("Failed to create Entity with Subject '" + entity.getSubject().getData() + "'.", e);
    }
}
 

@Override
public void create(final Event event) throws EventStorageException {
    requireNonNull(event);

    try {
        mongo.getDatabase(ryaInstanceName)
            .getCollection(COLLECTION_NAME)
            .insertOne(EVENT_CONVERTER.toDocument(event));
    } catch(final MongoException e) {
        final ErrorCategory category = ErrorCategory.fromErrorCode( e.getCode() );
        if(category == ErrorCategory.DUPLICATE_KEY) {
            throw new EventAlreadyExistsException("Failed to create Event with Subject '" + event.getSubject().getData() + "'.", e);
        }
        throw new EventStorageException("Failed to create Event with Subject '" + event.getSubject().getData() + "'.", e);
    }
}
 

public boolean acquireLock(MongoDatabase db) {

    Document insertObj = new Document(KEY_PROP_NAME, LOCK_ENTRY_KEY_VAL).append("status", "LOCK_HELD");

    // acquire lock by attempting to insert the same value in the collection - if it already exists (i.e. lock held)
    // there will be an exception
    try {
      db.getCollection(lockCollectionName).insertOne(insertObj);
    } catch (MongoWriteException ex) {
      if (ex.getError().getCategory() == ErrorCategory.DUPLICATE_KEY) {
        logger.warn("Duplicate key exception while acquireLock. Probably the lock has been already acquired.");
      }
      return false;
    }
    return true;
  }
 

/**
 * Checks if the given error is caused due to duplicate keys.
 *
 * @param error The error to check.
 * @return {@code true} if the given error is caused by duplicate keys.
 * @throws NullPointerException if the error is {@code null}.
 */
public static boolean isDuplicateKeyError(final Throwable error) {
    Objects.requireNonNull(error);

    if (error instanceof MongoException) {
        final MongoException mongoException = (MongoException) error;
        return ErrorCategory.fromErrorCode(mongoException.getCode()) == ErrorCategory.DUPLICATE_KEY;
    }
    return false;
}