Declare an entry in use for the remainder of its lifetime after it is used

with CGDataProviderCreateWithData.

Author: epatey

FastImageCache/FICImageTable.m

@@ -320,15 +320,21 @@ - (UIImage *)newImageForEntityUUID:(NSString *)entityUUID sourceImageUUID:(NSStr
                 [self saveMetadata];
             } else {
                 [self _entryWasAccessedWithEntityUUID:entityUUID];
-                
+
                 // Create CGImageRef whose backing store *is* the mapped image table entry. We avoid a memcpy this way.
                 CGDataProviderRef dataProvider = CGDataProviderCreateWithData((__bridge_retained void *)entryData, [entryData bytes], [entryData imageLength], _FICReleaseImageData);
-                
+
+                [_inUseEntries addObject:entityUUID];
+                __weak FICImageTable *weakSelf = self;
+                [entryData executeBlockOnDealloc:^{
+                    [weakSelf removeInUseForEntityUUID:entityUUID];
+                }];
+
                 CGSize pixelSize = [_imageFormat pixelSize];
                 CGBitmapInfo bitmapInfo = [_imageFormat bitmapInfo];
                 NSInteger bitsPerComponent = [_imageFormat bitsPerComponent];
                 NSInteger bitsPerPixel = [_imageFormat bytesPerPixel] * 8;
-                CGColorSpaceRef colorSpace = [_imageFormat isGrayscale] ? CGColorSpaceCreateDeviceGray() : CGColorSpaceCreateDeviceRGB();
+                CGColorSpaceRef colorSpace = [_imageFormat isGrayscale] ? CGColorSpaceCreateDeviceGray()    : CGColorSpaceCreateDeviceRGB();
 
                 CGImageRef imageRef = CGImageCreate(pixelSize.width, pixelSize.height, bitsPerComponent, bitsPerPixel, _imageRowLength, colorSpace, bitmapInfo, dataProvider, NULL, false, (CGColorRenderingIntent)0);
                 CGDataProviderRelease(dataProvider);
@@ -354,6 +360,12 @@ static void _FICReleaseImageData(void *info, const void *data, size_t size) {
     CFRelease(info);
 }
 
+- (void)removeInUseForEntityUUID:(NSString *)entityUUID {
+    [_lock lock];
+    [_inUseEntries removeObject:entityUUID];
+    [_lock unlock];
+}
+
 - (void)deleteEntryForEntityUUID:(NSString *)entityUUID {
     if (entityUUID != nil) {
         [_lock lock];
@@ -440,7 +452,7 @@ - (FICImageTableEntry *)_entryDataAtIndex:(NSInteger)index {
             off_t entryOffsetInChunk = entryOffset - chunkOffset;
             void *mappedChunkAddress = [chunk bytes];
             void *mappedEntryAddress = mappedChunkAddress + entryOffsetInChunk;
-            entryData = [[FICImageTableEntry alloc] initWithImageTableChunk:chunk bytes:mappedEntryAddress length:_entryLength];
+            entryData = [[FICImageTableEntry alloc] initWithImageTableChunk:chunk bytes:mappedEntryAddress length:_entryLength ];
         }
     }
 
@@ -464,15 +476,15 @@ - (NSInteger)_nextEntryIndex {
         NSString *oldestEvictableEntityUUID = [self oldestEvictableEntityUUID];
         if (oldestEvictableEntityUUID) {
             [self deleteEntryForEntityUUID:oldestEvictableEntityUUID];
-        index = [self _nextEntryIndex];
-    }
+            index = [self _nextEntryIndex];
+        }
     }
 
     if (index >= [self _maximumCount]) {
         NSString *message = [NSString stringWithFormat:@"FICImageTable - unable to evict entry from table '%@' to make room. New index %d, desired max %d", [_imageFormat name], index, [self _maximumCount]];
         [[FICImageCache sharedImageCache] _logMessage:message];
     }
-
+    
     return index;
 }
 

FastImageCache/FICImageTableEntry.h

@@ -69,6 +69,8 @@ typedef struct {
  */
 - (instancetype)initWithImageTableChunk:(FICImageTableChunk *)imageTableChunk bytes:(void *)bytes length:(size_t)length;
 
+- (void)executeBlockOnDealloc:(dispatch_block_t)block;
+
 ///--------------------------------------------
 /// @name Flushing a Modified Image Table Entry
 ///--------------------------------------------

FastImageCache/FICImageTableEntry.m

@@ -21,6 +21,7 @@ @interface FICImageTableEntry () {
     FICImageTableChunk *_imageTableChunk;
     void *_bytes;
     size_t _length;
+    dispatch_block_t _deallocBlock;
 }
 
 @end
@@ -64,10 +65,20 @@ - (id)initWithImageTableChunk:(FICImageTableChunk *)imageTableChunk bytes:(void
         _bytes = bytes;
         _length = length;
     }
-    
+
     return self;
 }
 
+- (void)executeBlockOnDealloc:(dispatch_block_t)block {
+    _deallocBlock = [block copy];
+}
+
+- (void)dealloc {
+    if (_deallocBlock) {
+        _deallocBlock();
+    }
+}
+
 #pragma mark - Other Accessors
 
 + (NSInteger)metadataVersion {