Sources/SPTPersistentCacheOptions.m

/*
 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 <SPTPersistentCache/SPTPersistentCacheOptions.h>
#import "SPTPersistentCacheObjectDescription.h"
#import "SPTPersistentCacheDebugUtilities.h"

#pragma mark - Constants

const NSUInteger SPTPersistentCacheDefaultExpirationTimeSec = 10 * 60;
const NSUInteger SPTPersistentCacheDefaultGCIntervalSec = 6 * 60 + 3;
static const NSUInteger SPTPersistentCacheDefaultCacheSizeInBytes = 0; // unbounded

const NSUInteger SPTPersistentCacheMinimumGCIntervalLimit = 60;
const NSUInteger SPTPersistentCacheMinimumExpirationLimit = 60;


#pragma mark Helper Functions

static NSUInteger SPTGuardedPropertyValue(NSUInteger proposedValue, NSUInteger minimumValue, SEL propertySelector, SPTPersistentCacheDebugCallback debugCallback);


#pragma mark - SPTPersistentCacheOptions Implementation

@implementation SPTPersistentCacheOptions

#pragma mark Object Life Cycle

- (instancetype)init
{
    self = [super init];

    if (self) {
        _cachePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"/com.spotify.temppersistent.image.cache"];
        _cacheIdentifier = @"persistent.cache";
        _useDirectorySeparation = YES;

        _garbageCollectionInterval = SPTPersistentCacheDefaultGCIntervalSec;
        _defaultExpirationPeriod = SPTPersistentCacheDefaultExpirationTimeSec;
        _sizeConstraintBytes = SPTPersistentCacheDefaultCacheSizeInBytes;
        _maxConcurrentOperations = NSOperationQueueDefaultMaxConcurrentOperationCount;
        _writePriority = NSOperationQueuePriorityNormal;
        _writeQualityOfService = NSQualityOfServiceDefault;
        _readPriority = NSOperationQueuePriorityNormal;
        _readQualityOfService = NSQualityOfServiceDefault;
        _deletePriority = NSOperationQueuePriorityNormal;
        _deleteQualityOfService = NSQualityOfServiceDefault;
        _garbageCollectionPriority = NSOperationQueuePriorityLow;
        _garbageCollectionQualityOfService = NSQualityOfServiceBackground;
    }

    return self;
}

#pragma mark Queue Management Options

- (NSString *)identifierForQueue
{
    return [NSString stringWithFormat:@"%@.queue.%lu.%lu.%p",
            self.cacheIdentifier,
            (unsigned long)self.garbageCollectionInterval,
            (unsigned long)self.defaultExpirationPeriod,
            (void *)self];
}

#pragma mark Garbage Collection Options

- (void)setGarbageCollectionInterval:(NSUInteger)garbageCollectionInterval
{
    if (_garbageCollectionInterval == garbageCollectionInterval) {
        return;
    }
    _garbageCollectionInterval = SPTGuardedPropertyValue(garbageCollectionInterval,
                                                         SPTPersistentCacheMinimumGCIntervalLimit,
                                                         @selector(garbageCollectionInterval),
                                                         self.debugOutput);
}

- (void)setDefaultExpirationPeriod:(NSUInteger)defaultExpirationPeriod
{
    if (_defaultExpirationPeriod == defaultExpirationPeriod) {
        return;
    }
    _defaultExpirationPeriod = SPTGuardedPropertyValue(defaultExpirationPeriod,
                                                       SPTPersistentCacheMinimumExpirationLimit,
                                                       @selector(defaultExpirationPeriod),
                                                       self.debugOutput);
}

#pragma mark NSCopying

- (id)copyWithZone:(NSZone *)zone
{
    SPTPersistentCacheOptions * const copy = [(SPTPersistentCacheOptions *)[self.class allocWithZone:zone] init];

    copy.cacheIdentifier = self.cacheIdentifier;
    copy.cachePath = self.cachePath;
    copy.useDirectorySeparation = self.useDirectorySeparation;

    copy.garbageCollectionInterval = self.garbageCollectionInterval;
    copy.defaultExpirationPeriod = self.defaultExpirationPeriod;
    copy.sizeConstraintBytes = self.sizeConstraintBytes;

    copy.debugOutput = self.debugOutput;
    copy.timingCallback = self.timingCallback;

    copy.maxConcurrentOperations = self.maxConcurrentOperations;
    copy.writePriority = self.writePriority;
    copy.writeQualityOfService = self.writeQualityOfService;
    copy.readPriority = self.readPriority;
    copy.readQualityOfService = self.readQualityOfService;
    copy.deletePriority = self.deletePriority;
    copy.deleteQualityOfService = self.deleteQualityOfService;
    copy.garbageCollectionPriority = self.garbageCollectionPriority;
    copy.garbageCollectionQualityOfService = self.garbageCollectionQualityOfService;

    return copy;
}

#pragma mark Describing an Object

- (NSString *)description
{
    return SPTPersistentCacheObjectDescription(self, self.cacheIdentifier, @"cache-identifier");
}

- (NSString *)debugDescription
{
    return SPTPersistentCacheObjectDescription(self,
                                               self.cacheIdentifier, @"cache-identifier",
                                               self.cachePath, @"cache-path",
                                               self.identifierForQueue, @"identifier-for-queue",
                                               @(self.useDirectorySeparation), @"use-directory-separation",
                                               @(self.garbageCollectionInterval), @"garbage-collection-interval",
                                               @(self.defaultExpirationPeriod), @"default-expiration-period",
                                               @(self.sizeConstraintBytes), @"size-constraint-bytes");
}

@end


@implementation SPTPersistentCacheOptions (Deprecated)

- (instancetype)initWithCachePath:(NSString *)cachePath
                       identifier:(NSString *)cacheIdentifier
        defaultExpirationInterval:(NSUInteger)defaultExpirationInterval
         garbageCollectorInterval:(NSUInteger)garbageCollectorInterval
                            debug:(nullable SPTPersistentCacheDebugCallback)debugCallback
{
    self = [self init];

    if (self) {
        _cachePath = [cachePath copy];
        _cacheIdentifier = [cacheIdentifier copy];

        _defaultExpirationPeriod = SPTGuardedPropertyValue(defaultExpirationInterval, SPTPersistentCacheMinimumExpirationLimit, @selector(defaultExpirationPeriod), debugCallback);
        _garbageCollectionInterval = SPTGuardedPropertyValue(garbageCollectorInterval, SPTPersistentCacheMinimumGCIntervalLimit, @selector(garbageCollectionInterval), debugCallback);

        _debugOutput = [debugCallback copy];
    }

    return self;
}

- (BOOL)folderSeparationEnabled
{
    return self.useDirectorySeparation;
}

- (void)setFolderSeparationEnabled:(BOOL)folderSeparationEnabled
{
    self.useDirectorySeparation = folderSeparationEnabled;
}

- (NSUInteger)gcIntervalSec
{
    return self.garbageCollectionInterval;
}

- (NSUInteger)defaultExpirationPeriodSec
{
    return self.defaultExpirationPeriod;
}

@end


static NSUInteger SPTGuardedPropertyValue(NSUInteger proposedValue, NSUInteger minimumValue, SEL propertySelector, SPTPersistentCacheDebugCallback debugCallback)
{
    if (proposedValue >= minimumValue) {
        return proposedValue;
    }

    SPTPersistentCacheSafeDebugCallback([NSString stringWithFormat:@"PersistentDataCache: Forcing \"%@\" to %lu seconds", NSStringFromSelector(propertySelector), (unsigned long)SPTPersistentCacheMinimumExpirationLimit], debugCallback);
    return minimumValue;
}