option to prevent cache reads from updating entry's modification date

TMCache/TMDiskCache.h

@@ -79,6 +79,12 @@ typedef void (^TMDiskCacheObjectBlock)(TMDiskCache *cache, NSString *key, id <NS
  */
 @property (assign) NSTimeInterval ageLimit;
 
+/**
+ A flag that determines whether reading from the cache should update the entry's modification
+ date.  Cache objects become stale if they haven't been overwritten wihtin the age limit.  Default is YES.
+ */
+@property (assign) BOOL updateEntryDateOnRead;
+
 #pragma mark -
 /// @name Event Blocks
 

TMCache/TMDiskCache.m

@@ -35,6 +35,7 @@ @implementation TMDiskCache
 @synthesize didRemoveAllObjectsBlock = _didRemoveAllObjectsBlock;
 @synthesize byteLimit = _byteLimit;
 @synthesize ageLimit = _ageLimit;
+@synthesize updateEntryDateOnRead = _updateEntryDateOnRead;
 
 #pragma mark - Initialization -
 
@@ -57,6 +58,7 @@ - (instancetype)initWithName:(NSString *)name
         _byteCount = 0;
         _byteLimit = 0;
         _ageLimit = 0.0;
+        _updateEntryDateOnRead = YES;
 
         _dates = [[NSMutableDictionary alloc] init];
         _sizes = [[NSMutableDictionary alloc] init];
@@ -402,7 +404,8 @@ - (void)objectForKey:(NSString *)key block:(TMDiskCacheObjectBlock)block
 
         if ([[NSFileManager defaultManager] fileExistsAtPath:[fileURL path]]) {
             object = [NSKeyedUnarchiver unarchiveObjectWithFile:[fileURL path]];
-            [strongSelf setFileModificationDate:now forURL:fileURL];
+            if (_updateEntryDateOnRead)
+                [strongSelf setFileModificationDate:now forURL:fileURL];
         }
 
         block(strongSelf, key, object, fileURL);
@@ -426,6 +429,7 @@ - (void)fileURLForKey:(NSString *)key block:(TMDiskCacheObjectBlock)block
         NSURL *fileURL = [strongSelf encodedFileURLForKey:key];
 
         if ([[NSFileManager defaultManager] fileExistsAtPath:[fileURL path]]) {
+          if (_updateEntryDateOnRead)
             [strongSelf setFileModificationDate:now forURL:fileURL];
         } else {
             fileURL = nil;
@@ -1033,4 +1037,28 @@ - (void)setAgeLimit:(NSTimeInterval)ageLimit
     });
 }
 
+- (BOOL)updateEntryDateOnRead
+{
+  __block BOOL updateEntryDateOnRead = NO;
+
+  dispatch_sync(_queue, ^{
+    updateEntryDateOnRead = _updateEntryDateOnRead;
+  });
+
+  return updateEntryDateOnRead;
+}
+
+- (void)setUpdateEntryDateOnRead:(BOOL)updateEntryDateOnRead
+{
+    __weak TMDiskCache *weakSelf = self;
+
+    dispatch_barrier_async(_queue, ^{
+        TMDiskCache *strongSelf = weakSelf;
+        if (!strongSelf)
+            return;
+
+        strongSelf->_updateEntryDateOnRead = updateEntryDateOnRead;
+    });
+}
+
 @end

TMCache/TMMemoryCache.h

@@ -48,6 +48,12 @@ typedef void (^TMMemoryCacheObjectBlock)(TMMemoryCache *cache, NSString *key, id
  */
 @property (assign) NSTimeInterval ageLimit;
 
+/**
+ A flag that determines whether reading from the cache should update the entry's modification
+ date.  Cache objects become stale if they haven't been overwritten wihtin the age limit.  Default is YES.
+ */
+@property (assign) BOOL updateEntryDateOnRead;
+
 /**
  When `YES` on iOS the cache will remove all objects when the app receives a memory warning.
  Defaults to `YES`.

TMCache/TMMemoryCache.m

@@ -18,6 +18,7 @@ @implementation TMMemoryCache
 @synthesize ageLimit = _ageLimit;
 @synthesize costLimit = _costLimit;
 @synthesize totalCost = _totalCost;
+@synthesize updateEntryDateOnRead = _updateEntryDateOnRead;
 @synthesize willAddObjectBlock = _willAddObjectBlock;
 @synthesize willRemoveObjectBlock = _willRemoveObjectBlock;
 @synthesize willRemoveAllObjectsBlock = _willRemoveAllObjectsBlock;
@@ -63,6 +64,7 @@ - (id)init
         _ageLimit = 0.0;
         _costLimit = 0;
         _totalCost = 0;
+        _updateEntryDateOnRead = YES;
 
         _removeAllObjectsOnMemoryWarning = YES;
         _removeAllObjectsOnEnteringBackground = YES;
@@ -243,7 +245,7 @@ - (void)objectForKey:(NSString *)key block:(TMMemoryCacheObjectBlock)block
             __weak TMMemoryCache *weakSelf = strongSelf;
             dispatch_barrier_async(strongSelf->_queue, ^{
                 TMMemoryCache *strongSelf = weakSelf;
-                if (strongSelf)
+                if (strongSelf && _updateEntryDateOnRead)
                     [strongSelf->_dates setObject:now forKey:key];
             });
         }
@@ -867,4 +869,28 @@ - (NSUInteger)totalCost
     return cost;
 }
 
+- (BOOL)updateEntryDateOnRead
+{
+  __block BOOL updateEntryDateOnRead = NO;
+
+  dispatch_sync(_queue, ^{
+    updateEntryDateOnRead = _updateEntryDateOnRead;
+  });
+
+  return updateEntryDateOnRead;
+}
+
+- (void)setUpdateEntryDateOnRead:(BOOL)updateEntryDateOnRead
+{
+    __weak TMMemoryCache *weakSelf = self;
+
+    dispatch_barrier_async(_queue, ^{
+        TMMemoryCache *strongSelf = weakSelf;
+        if (!strongSelf)
+            return;
+
+        strongSelf->_updateEntryDateOnRead = updateEntryDateOnRead;
+  });
+}
+
 @end

TMCacheYelpFork.podspec

@@ -0,0 +1,17 @@
+Pod::Spec.new do |s|
+  s.name          = 'TMCacheYelpFork'
+  s.version       = '1.2.2'
+  s.source_files  = 'TMCache/*.{h,m}'
+  s.homepage      = 'https://github.com/Yelp/TMCache'
+  s.summary       = 'Fast parallel object cache for iOS and OS X. Yelp fork.'
+  s.authors       = { 'Justin Ouellette' => 'jstn@tumblr.com' }
+  s.source        = { :git => 'https://github.com/Yelp/TMCache.git', :tag => 'v' + s.version.to_s }
+  s.license       = { :type => 'Apache 2.0', :file => 'LICENSE.txt' }
+  s.header_dir    = 'TMCache'
+  s.requires_arc  = true
+  s.frameworks    = 'Foundation'
+  s.ios.weak_frameworks   = 'UIKit'
+  s.osx.weak_frameworks   = 'AppKit'
+  s.ios.deployment_target = '5.0'
+  s.osx.deployment_target = '10.7'
+end