SDMemoryCache.m
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/*
* This file is part of the SDWebImage package.
* (c) Olivier Poitrey <rs@dailymotion.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
#import "SDMemoryCache.h"
#import "SDImageCacheConfig.h"
NSUInteger SDMemoryCacheCostForImage(UIImage * _Nullable image) {
#if SD_MAC
return image.size.height * image.size.width;
#elif SD_UIKIT || SD_WATCH
return image.size.height * image.size.width * image.scale * image.scale;
#endif
}
static void * SDMemoryCacheContext = &SDMemoryCacheContext;
@interface SDMemoryCache <KeyType, ObjectType> ()
@property (nonatomic, strong, nullable) SDImageCacheConfig *config;
@property (nonatomic, strong, nonnull) NSMapTable<KeyType, ObjectType> *weakCache; // strong-weak cache
@property (nonatomic, strong, nonnull) dispatch_semaphore_t weakCacheLock; // a lock to keep the access to `weakCache` thread-safe
@end
@implementation SDMemoryCache
- (void)dealloc {
[_config removeObserver:self forKeyPath:NSStringFromSelector(@selector(maxMemoryCost)) context:SDMemoryCacheContext];
[_config removeObserver:self forKeyPath:NSStringFromSelector(@selector(maxMemoryCount)) context:SDMemoryCacheContext];
#if SD_UIKIT
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
#endif
}
- (instancetype)init {
self = [super init];
if (self) {
_config = [[SDImageCacheConfig alloc] init];
[self commonInit];
}
return self;
}
- (instancetype)initWithConfig:(SDImageCacheConfig *)config {
self = [super init];
if (self) {
_config = config;
[self commonInit];
}
return self;
}
- (void)commonInit {
self.weakCache = [[NSMapTable alloc] initWithKeyOptions:NSPointerFunctionsStrongMemory valueOptions:NSPointerFunctionsWeakMemory capacity:0];
self.weakCacheLock = dispatch_semaphore_create(1);
SDImageCacheConfig *config = self.config;
self.totalCostLimit = config.maxMemoryCost;
self.countLimit = config.maxMemoryCount;
[config addObserver:self forKeyPath:NSStringFromSelector(@selector(maxMemoryCost)) options:0 context:SDMemoryCacheContext];
[config addObserver:self forKeyPath:NSStringFromSelector(@selector(maxMemoryCount)) options:0 context:SDMemoryCacheContext];
#if SD_UIKIT
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(didReceiveMemoryWarning:)
name:UIApplicationDidReceiveMemoryWarningNotification
object:nil];
#endif
}
// Current this seems no use on macOS (macOS use virtual memory and do not clear cache when memory warning). So we only override on iOS/tvOS platform.
#if SD_UIKIT
- (void)didReceiveMemoryWarning:(NSNotification *)notification {
// Only remove cache, but keep weak cache
[super removeAllObjects];
}
// `setObject:forKey:` just call this with 0 cost. Override this is enough
- (void)setObject:(id)obj forKey:(id)key cost:(NSUInteger)g {
[super setObject:obj forKey:key cost:g];
if (!self.config.shouldUseWeakMemoryCache) {
return;
}
if (key && obj) {
// Store weak cache
LOCK(self.weakCacheLock);
[self.weakCache setObject:obj forKey:key];
UNLOCK(self.weakCacheLock);
}
}
- (id)objectForKey:(id)key {
id obj = [super objectForKey:key];
if (!self.config.shouldUseWeakMemoryCache) {
return obj;
}
if (key && !obj) {
// Check weak cache
LOCK(self.weakCacheLock);
obj = [self.weakCache objectForKey:key];
UNLOCK(self.weakCacheLock);
if (obj) {
// Sync cache
NSUInteger cost = 0;
if ([obj isKindOfClass:[UIImage class]]) {
cost = SDMemoryCacheCostForImage(obj);
}
[super setObject:obj forKey:key cost:cost];
}
}
return obj;
}
- (void)removeObjectForKey:(id)key {
[super removeObjectForKey:key];
if (!self.config.shouldUseWeakMemoryCache) {
return;
}
if (key) {
// Remove weak cache
LOCK(self.weakCacheLock);
[self.weakCache removeObjectForKey:key];
UNLOCK(self.weakCacheLock);
}
}
- (void)removeAllObjects {
[super removeAllObjects];
if (!self.config.shouldUseWeakMemoryCache) {
return;
}
// Manually remove should also remove weak cache
LOCK(self.weakCacheLock);
[self.weakCache removeAllObjects];
UNLOCK(self.weakCacheLock);
}
#endif
#pragma mark - KVO
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
if (context == SDMemoryCacheContext) {
if ([keyPath isEqualToString:NSStringFromSelector(@selector(maxMemoryCost))]) {
self.totalCostLimit = self.config.maxMemoryCost;
} else if ([keyPath isEqualToString:NSStringFromSelector(@selector(maxMemoryCount))]) {
self.countLimit = self.config.maxMemoryCount;
}
} else {
[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
}
}
@end