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Fix some thread unsafe operations
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Olivier Poitrey committed Aug 29, 2010
1 parent a0c0bef commit 368a0a0
Showing 1 changed file with 88 additions and 58 deletions.
146 changes: 88 additions & 58 deletions SDURLCache.m
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Original file line number Diff line number Diff line change
Expand Up @@ -204,43 +204,54 @@ - (NSMutableDictionary *)diskCacheInfo
{
if (!diskCacheInfo)
{
diskCacheInfo = [[NSMutableDictionary alloc] initWithContentsOfFile:[diskCachePath stringByAppendingPathComponent:kSDURLCacheInfoFileName]];
if (!diskCacheInfo)
@synchronized(self)
{
diskCacheInfo = [[NSMutableDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithUnsignedInt:0], kSDURLCacheInfoDiskUsageKey,
[NSMutableDictionary dictionary], kSDURLCacheInfoAccessesKey,
[NSMutableDictionary dictionary], kSDURLCacheInfoSizesKey,
nil];
}
diskCacheInfoDirty = NO;
if (!diskCacheInfo) // Check again, maybe another thread created it while waiting for the mutex
{
diskCacheInfo = [[NSMutableDictionary alloc] initWithContentsOfFile:[diskCachePath stringByAppendingPathComponent:kSDURLCacheInfoFileName]];
if (!diskCacheInfo)
{
diskCacheInfo = [[NSMutableDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithUnsignedInt:0], kSDURLCacheInfoDiskUsageKey,
[NSMutableDictionary dictionary], kSDURLCacheInfoAccessesKey,
[NSMutableDictionary dictionary], kSDURLCacheInfoSizesKey,
nil];
}
diskCacheInfoDirty = NO;

periodicMaintenanceTimer = [[NSTimer scheduledTimerWithTimeInterval:5
target:self
selector:@selector(periodicMaintenance)
userInfo:nil
repeats:YES] retain];
periodicMaintenanceTimer = [[NSTimer scheduledTimerWithTimeInterval:5
target:self
selector:@selector(periodicMaintenance)
userInfo:nil
repeats:YES] retain];
}
}
}

return diskCacheInfo;
}

- (void)createDiskCachePath
{
if (![[NSFileManager defaultManager] fileExistsAtPath:diskCachePath])
NSFileManager *fileManager = [[NSFileManager alloc] init];
if (![fileManager fileExistsAtPath:diskCachePath])
{
[[NSFileManager defaultManager] createDirectoryAtPath:diskCachePath
withIntermediateDirectories:YES
attributes:nil
error:NULL];
[fileManager createDirectoryAtPath:diskCachePath
withIntermediateDirectories:YES
attributes:nil
error:NULL];
}
[fileManager release];
}

- (void)saveCacheInfo
{
[self createDiskCachePath];
[self.diskCacheInfo writeToFile:[diskCachePath stringByAppendingPathComponent:kSDURLCacheInfoFileName] atomically:YES];
diskCacheInfoDirty = NO;
@synchronized(self.diskCacheInfo)
{
[self.diskCacheInfo writeToFile:[diskCachePath stringByAppendingPathComponent:kSDURLCacheInfoFileName] atomically:YES];
diskCacheInfoDirty = NO;
}
}

- (void)removeCachedResponseForCachedKeys:(NSArray *)cacheKeys
Expand All @@ -250,17 +261,24 @@ - (void)removeCachedResponseForCachedKeys:(NSArray *)cacheKeys
NSEnumerator *enumerator = [cacheKeys objectEnumerator];
NSString *cacheKey;

NSMutableDictionary *accesses = [self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey];
NSMutableDictionary *sizes = [self.diskCacheInfo objectForKey:kSDURLCacheInfoSizesKey];

while ((cacheKey = [enumerator nextObject]))
@synchronized(self.diskCacheInfo)
{
NSUInteger cacheItemSize = [[sizes objectForKey:cacheKey] unsignedIntegerValue];
[accesses removeObjectForKey:cacheKey];
[sizes removeObjectForKey:cacheKey];
[[NSFileManager defaultManager] removeItemAtPath:[diskCachePath stringByAppendingPathComponent:cacheKey] error:NULL];
diskCacheUsage -= cacheItemSize;
[self.diskCacheInfo setObject:[NSNumber numberWithUnsignedInteger:diskCacheUsage] forKey:kSDURLCacheInfoDiskUsageKey];
NSMutableDictionary *accesses = [self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey];
NSMutableDictionary *sizes = [self.diskCacheInfo objectForKey:kSDURLCacheInfoSizesKey];
NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];

while ((cacheKey = [enumerator nextObject]))
{
NSUInteger cacheItemSize = [[sizes objectForKey:cacheKey] unsignedIntegerValue];
[accesses removeObjectForKey:cacheKey];
[sizes removeObjectForKey:cacheKey];
[fileManager removeItemAtPath:[diskCachePath stringByAppendingPathComponent:cacheKey] error:NULL];
diskCacheUsage -= cacheItemSize;
@synchronized(self.diskCacheInfo)
{
[self.diskCacheInfo setObject:[NSNumber numberWithUnsignedInteger:diskCacheUsage] forKey:kSDURLCacheInfoDiskUsageKey];
}
}
}

[pool drain];
Expand All @@ -274,19 +292,23 @@ - (void)balanceDiskUsage
return;
}

// Apply LRU cache eviction algorithm while disk usage outreach capacity
NSDictionary *sizes = [self.diskCacheInfo objectForKey:kSDURLCacheInfoSizesKey];
NSMutableArray *keysToRemove = [NSMutableArray array];

NSInteger capacityToSave = diskCacheUsage - self.diskCapacity;
NSArray *sortedKeys = [(NSDictionary *)[self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey] keysSortedByValueUsingSelector:@selector(compare:)];
NSEnumerator *enumerator = [sortedKeys objectEnumerator];
NSString *cacheKey;

while (capacityToSave > 0 && (cacheKey = [enumerator nextObject]))
@synchronized(self.diskCacheInfo)
{
[keysToRemove addObject:cacheKey];
capacityToSave -= [(NSNumber *)[sizes objectForKey:cacheKey] unsignedIntegerValue];
// Apply LRU cache eviction algorithm while disk usage outreach capacity
NSDictionary *sizes = [self.diskCacheInfo objectForKey:kSDURLCacheInfoSizesKey];

NSInteger capacityToSave = diskCacheUsage - self.diskCapacity;
NSArray *sortedKeys = [[self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey] keysSortedByValueUsingSelector:@selector(compare:)];
NSEnumerator *enumerator = [sortedKeys objectEnumerator];
NSString *cacheKey;

while (capacityToSave > 0 && (cacheKey = [enumerator nextObject]))
{
[keysToRemove addObject:cacheKey];
capacityToSave -= [(NSNumber *)[sizes objectForKey:cacheKey] unsignedIntegerValue];
}
}

[self removeCachedResponseForCachedKeys:keysToRemove];
Expand All @@ -312,14 +334,19 @@ - (void)storeToDisk:(NSDictionary *)context
}

// Update disk usage info
NSNumber *cacheItemSize = [[[NSFileManager defaultManager] attributesOfItemAtPath:cacheFilePath error:NULL] objectForKey:NSFileSize];
NSFileManager *fileManager = [[NSFileManager alloc] init];
NSNumber *cacheItemSize = [[fileManager attributesOfItemAtPath:cacheFilePath error:NULL] objectForKey:NSFileSize];
[fileManager release];
diskCacheUsage += [cacheItemSize unsignedIntegerValue];
[self.diskCacheInfo setObject:[NSNumber numberWithUnsignedInteger:diskCacheUsage] forKey:kSDURLCacheInfoDiskUsageKey];
@synchronized(self.diskCacheInfo)
{
[self.diskCacheInfo setObject:[NSNumber numberWithUnsignedInteger:diskCacheUsage] forKey:kSDURLCacheInfoDiskUsageKey];


// Update cache info for the stored item
[(NSMutableDictionary *)[self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey] setObject:[NSDate date] forKey:cacheKey];
[(NSMutableDictionary *)[self.diskCacheInfo objectForKey:kSDURLCacheInfoSizesKey] setObject:cacheItemSize forKey:cacheKey];
// Update cache info for the stored item
[(NSMutableDictionary *)[self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey] setObject:[NSDate date] forKey:cacheKey];
[(NSMutableDictionary *)[self.diskCacheInfo objectForKey:kSDURLCacheInfoSizesKey] setObject:cacheItemSize forKey:cacheKey];
}

[self saveCacheInfo];
}
Expand Down Expand Up @@ -416,20 +443,23 @@ - (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request

// NOTE: We don't handle expiration here as even staled cache data is necessary for NSURLConnection to handle cache revalidation.
// Staled cache data is also needed for cachePolicies which force the use of the cache.
NSMutableDictionary *accesses = [self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey];
if ([accesses objectForKey:cacheKey]) // OPTI: Check for cache-hit in a in-memory dictionnary before to hit the FS
@synchronized(self.diskCacheInfo)
{
NSCachedURLResponse *diskResponse = [NSKeyedUnarchiver unarchiveObjectWithFile:[diskCachePath stringByAppendingPathComponent:cacheKey]];
if (diskResponse)
NSMutableDictionary *accesses = [self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey];
if ([accesses objectForKey:cacheKey]) // OPTI: Check for cache-hit in a in-memory dictionnary before to hit the FS
{
// OPTI: Log the entry last access time for LRU cache eviction algorithm but don't save the dictionary
// on disk now in order to save IO and time
[accesses setObject:[NSDate date] forKey:cacheKey];
diskCacheInfoDirty = YES;

// OPTI: Store the response to memory cache for potential future requests
[super storeCachedResponse:diskResponse forRequest:request];
return diskResponse;
NSCachedURLResponse *diskResponse = [NSKeyedUnarchiver unarchiveObjectWithFile:[diskCachePath stringByAppendingPathComponent:cacheKey]];
if (diskResponse)
{
// OPTI: Log the entry last access time for LRU cache eviction algorithm but don't save the dictionary
// on disk now in order to save IO and time
[accesses setObject:[NSDate date] forKey:cacheKey];
diskCacheInfoDirty = YES;

// OPTI: Store the response to memory cache for potential future requests
[super storeCachedResponse:diskResponse forRequest:request];
return diskResponse;
}
}
}

Expand Down

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