private void UpdateCustomerExternalIdentityMapCache(RequestContext requestContext, string externalIdentityId, string externalIdentityIssuer)
            {
                CustomerExternalIdentityMap      customerExternalIdentityMap = this.GetCustomerAccountByExternalIdentityFromDb(requestContext, externalIdentityId, externalIdentityIssuer);
                CustomerL2CacheDataStoreAccessor levelL2CacheDataAccessor    = this.GetCustomerL2CacheDataStoreAccessor(requestContext);

                levelL2CacheDataAccessor.CacheCustomerAccountByExternalIdentity(externalIdentityId, externalIdentityIssuer, customerExternalIdentityMap);
            }
            /// <summary>
            /// Gets the customer account by external identity.
            /// </summary>
            /// <param name="request">The data service request.</param>
            /// <returns>The data service response.</returns>
            private SingleEntityDataServiceResponse <CustomerExternalIdentityMap> GetCustomerAccountByExternalIdentity(GetCustomerAccountByExternalIdentityDataRequest request)
            {
                CustomerL2CacheDataStoreAccessor levelL2CacheDataAccessor = this.GetCustomerL2CacheDataStoreAccessor(request.RequestContext);
                bool foundInCache;
                bool updateCache;

                CustomerExternalIdentityMap customerExternalIdentityMap = DataManager.GetDataFromCache(() => levelL2CacheDataAccessor.GetCustomerAccountByExternalIdentity(request.ExternalIdentityId, request.ExternalIdentityIssuer), out foundInCache, out updateCache);

                if (!foundInCache)
                {
                    customerExternalIdentityMap = this.GetCustomerAccountByExternalIdentityFromDb(request.RequestContext, request.ExternalIdentityId, request.ExternalIdentityIssuer);
                }

                if (updateCache && (customerExternalIdentityMap != null))
                {
                    levelL2CacheDataAccessor.CacheCustomerAccountByExternalIdentity(request.ExternalIdentityId, request.ExternalIdentityIssuer, customerExternalIdentityMap);
                }

                return(new SingleEntityDataServiceResponse <CustomerExternalIdentityMap>(customerExternalIdentityMap));
            }