Sources/SPTPersistentCacheGarbageCollector.h

/*
 Copyright (c) 2015-2021 Spotify AB.

 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 <Foundation/Foundation.h>

@class SPTPersistentCache;
@class SPTPersistentCacheOptions;

@interface SPTPersistentCacheGarbageCollector : NSObject

/**
 Persistent Cache that will be used for garbage collection operations.
 */
@property (nonatomic, weak, readonly) SPTPersistentCache *cache;

/**
 Dispatch queue where the operations will take place.
 */
@property (nonatomic, strong, readonly) NSOperationQueue *queue;

/**
 Returns YES if the internal timer of proxy is scheduled to perform garbage collection of the cache.
 */
@property (nonatomic, readonly, getter=isGarbageCollectionScheduled) BOOL garbageCollectionScheduled;

/**
 Initializes the timer proxy on a specific queue using a specific data cache.

 @param cache Persistent Cache that will be used for garbage collection operations.
 @param options Cache options to configure this garbage collector.
 @param queue NSOperation queue where the operations will take place.
 */
- (instancetype)initWithCache:(SPTPersistentCache *)cache
                      options:(SPTPersistentCacheOptions *)options
                        queue:(NSOperationQueue *)queue;

/**
 Schedules the garbage collection operation.

 @warning The owner of the reference to this object should call 
 unscheduleGarbageCollection on its dealloc method to prevent a retain cycle 
 caused by an internal timer.
 */
- (void)schedule;

/**
 Unschedules the garbage collection operation.

 @warning Ensure the garbage collector is unscheduled to break the retain
 cycle that could be caused by the internal timer in this class.
 */
- (void)unschedule;

@end