RMMemoryCache.m
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//
// RMMemoryCache.m
//
// Copyright (c) 2008-2009, Route-Me Contributors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
#import "RMMemoryCache.h"
#import "RMTileImage.h"
@implementation RMMemoryCache
- (id)initWithCapacity:(NSUInteger)aCapacity
{
if (!(self = [super init]))
return nil;
RMLog(@"initializing memory cache %@ with capacity %d", self, aCapacity);
cache = [[NSMutableDictionary alloc] initWithCapacity:aCapacity];
if (aCapacity < 1)
aCapacity = 1;
capacity = aCapacity;
return self;
}
- (id)init
{
return [self initWithCapacity:32];
}
- (void)dealloc
{
[cache release];
[super dealloc];
}
- (void)didReceiveMemoryWarning
{
LogMethod();
@synchronized(cache) {
[cache removeAllObjects];
}
}
- (void)removeTile:(RMTile)tile
{
@synchronized(cache) {
[cache removeObjectForKey:[RMTileCache tileHash:tile]];
}
}
- (UIImage *)cachedImage:(RMTile)tile withCacheKey:(NSString *)aCacheKey
{
// RMLog(@"Memory cache check tile %d %d %d (%@)", tile.x, tile.y, tile.zoom, [RMTileCache tileHash:tile]);
RMCacheObject *cachedObject = nil;
NSNumber *tileHash = [RMTileCache tileHash:tile];
@synchronized(cache) {
cachedObject = [cache objectForKey:tileHash];
if (!cachedObject)
return nil;
if (![[cachedObject cacheKey] isEqualToString:aCacheKey]) {
[cache removeObjectForKey:tileHash];
return nil;
}
}
// RMLog(@"Memory cache hit tile %d %d %d (%@)", tile.x, tile.y, tile.zoom, [RMTileCache tileHash:tile]);
[cachedObject touch];
return [cachedObject cachedObject];
}
/// Remove the least-recently used image from cache, if cache is at or over capacity. Removes only 1 image.
- (void)makeSpaceInCache
{
@synchronized(cache) {
while ([cache count] >= capacity)
{
// Rather than scanning I would really like to be using a priority queue
// backed by a heap here.
// Maybe deleting one random element would work as well.
NSEnumerator *enumerator = [cache objectEnumerator];
RMCacheObject *image;
NSDate *oldestDate = nil;
RMCacheObject *oldestImage = nil;
while ((image = (RMCacheObject *)[enumerator nextObject]))
{
if (oldestDate == nil || ([oldestDate timeIntervalSinceReferenceDate] > [[image timestamp] timeIntervalSinceReferenceDate]))
{
oldestDate = [image timestamp];
oldestImage = image;
}
}
if (oldestImage) {
// RMLog(@"Memory cache delete tile %d %d %d (%@)", oldestImage.tile.x, oldestImage.tile.y, oldestImage.tile.zoom, [RMTileCache tileHash:oldestImage.tile]);
[cache removeObjectForKey:[RMTileCache tileHash:oldestImage.tile]];
}
}
}
}
- (void)addImage:(UIImage *)image forTile:(RMTile)tile withCacheKey:(NSString *)aCacheKey
{
// RMLog(@"Memory cache insert tile %d %d %d (%@)", tile.x, tile.y, tile.zoom, [RMTileCache tileHash:tile]);
[self makeSpaceInCache];
@synchronized(cache) {
[cache setObject:[RMCacheObject cacheObject:image forTile:tile withCacheKey:aCacheKey] forKey:[RMTileCache tileHash:tile]];
}
}
- (void)removeAllCachedImages
{
LogMethod();
@synchronized(cache) {
[cache removeAllObjects];
}
}
@end