/*
 * 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.
 */

#import "HttpdnsScheduleCenter.h"
#import "HttpdnsPersistenceUtils.h"
#import "HttpdnsLog_Internal.h"
#import "HttpdnsInternalConstant.h"
#import "HttpdnsRequestManager.h"
#import "HttpdnsService_Internal.h"
#import "HttpdnsScheduleExecutor.h"
#import "HttpdnsRemoteResolver.h"
#import "HttpdnsUtil.h"
#import "HttpdnsPublicConstant.h"
#import "HttpdnsRegionConfigLoader.h"
#import "HttpdnsIpStackDetector.h"

static NSString *const kLastUpdateUnixTimestampKey = @"last_update_unix_timestamp";
static NSString *const kScheduleRegionConfigLocalCacheFileName = @"schedule_center_result";

static int const MAX_UPDATE_RETRY_COUNT = 2;

@interface HttpdnsScheduleCenter ()