Fixes a bug that causes image retrieval to never complete if it depends on an source image URL whose request is already in flight.

The bug is that are many scenarios in which _processImage:forEntity:withFormatName:formatName:completionBlocksDictionary:completionBlocksDictionary fails to call all completion blocks. Here are the simplest repro steps.
- Formats A and B (neither of which are in a family)
- Entity X
- Both X(A) and X(B) rely on the same source image url
- Retrieve X(A) and then X(B) prior to source image becoming available
- When source image becomes available the image is processed and completion blocks called for A, but not B.

The fix is to redo the calculation of the list of formats that should be processed when a source image becomes available.

Author: epatey

FastImageCache/FICImageCache.m

@@ -248,7 +248,7 @@ - (void)_imageDidLoad:(UIImage *)image forURL:(NSURL *)URL {
             NSString *formatName = [entityDictionary objectForKey:FICImageCacheFormatKey];
             NSDictionary *completionBlocksDictionary = [entityDictionary objectForKey:FICImageCacheCompletionBlocksKey];
             if (image != nil){
-                [self _processImage:image forEntity:entity withFormatName:formatName completionBlocksDictionary:completionBlocksDictionary];
+                [self _processImage:image forEntity:entity completionBlocksDictionary:completionBlocksDictionary];
             } else {
                 NSArray *completionBlocks = [completionBlocksDictionary objectForKey:formatName];
                 if (completionBlocks != nil) {
@@ -312,41 +312,18 @@ - (void)setImage:(UIImage *)image forEntity:(id <FICEntity>)entity withFormatNam
         if (imageTable) {
             [imageTable deleteEntryForEntityUUID:entityUUID];
 
-            [self _processImage:image forEntity:entity withFormatName:formatName completionBlocksDictionary:completionBlocksDictionary];
+            [self _processImage:image forEntity:entity completionBlocksDictionary:completionBlocksDictionary];
         } else {
             [self _logMessage:[NSString stringWithFormat:@"*** FIC Error: %s Couldn't find image table with format name %@", __PRETTY_FUNCTION__, formatName]];
         }
     }
 }
 
-- (void)_processImage:(UIImage *)image forEntity:(id <FICEntity>)entity withFormatName:(NSString *)formatName completionBlocksDictionary:(NSDictionary *)completionBlocksDictionary {
-    FICImageFormat *imageFormat = [_formats objectForKey:formatName];
-    NSString *formatFamily = [imageFormat family];
-    NSString *entityUUID = [entity UUID];
-    NSString *sourceImageUUID = [entity sourceImageUUID];
-    
-    if (formatFamily != nil) {
-        BOOL shouldProcessAllFormatsInFamily = YES;
-        if (_delegateImplementsShouldProcessAllFormatsInFamilyForEntity) {
-            shouldProcessAllFormatsInFamily = [_delegate imageCache:self shouldProcessAllFormatsInFamily:formatFamily forEntity:entity];
-        }
-        // All of the formats in a given family use the same source asset, so once we have that source asset, we can generate all of the family's formats.
-        for (FICImageTable *table in [_imageTables allValues]) {
-            FICImageFormat *imageFormat = [table imageFormat];
-            NSString *tableFormatFamily = [imageFormat family];
-            if ([formatFamily isEqualToString:tableFormatFamily]) {
-                NSArray *completionBlocks = [completionBlocksDictionary objectForKey:[imageFormat name]];
-                
-                BOOL imageExistsForEntity = [table entryExistsForEntityUUID:entityUUID sourceImageUUID:sourceImageUUID];
-                BOOL shouldProcessFamilyFormat = shouldProcessAllFormatsInFamily && imageExistsForEntity == NO;
-                if (shouldProcessFamilyFormat || [completionBlocks count] > 0) {
-                    [self _processImage:image forEntity:entity imageTable:table completionBlocks:completionBlocks];
-                }
-            }
-        }
-    } else {
-        FICImageTable *imageTable = [_imageTables objectForKey:formatName];
-        NSArray *completionBlocks = [completionBlocksDictionary objectForKey:formatName];
+- (void)_processImage:(UIImage *)image forEntity:(id <FICEntity>)entity completionBlocksDictionary:(NSDictionary *)completionBlocksDictionary {
+    for (NSString *formatToProcess in [self formatsToProcessForCompletionBlocks:completionBlocksDictionary
+                                                                         entity:entity]) {
+        FICImageTable *imageTable = [_imageTables objectForKey:formatToProcess];
+        NSArray *completionBlocks = [completionBlocksDictionary objectForKey:formatToProcess];
         [self _processImage:image forEntity:entity imageTable:imageTable completionBlocks:completionBlocks];
     }
 }
@@ -386,6 +363,58 @@ - (void)_processImage:(UIImage *)image forEntity:(id <FICEntity>)entity imageTab
     }
 }
 
+- (NSSet *)formatsToProcessForCompletionBlocks:(NSDictionary *)completionBlocksDictionary entity:(id <FICEntity>)entity {
+    // At the very least, we must process all formats with pending completion blocks
+    NSMutableSet *formatsToProcess = [NSMutableSet setWithArray:completionBlocksDictionary.allKeys];
+
+    // Get the list of format families included by the formats we have to process
+    NSMutableSet *families;
+    for (NSString *formatToProcess in formatsToProcess) {
+        FICImageTable *imageTable = _imageTables[formatToProcess];
+        FICImageFormat *imageFormat = imageTable.imageFormat;
+        NSString *tableFormatFamily = imageFormat.family;
+        if (tableFormatFamily) {
+            if (!families) {
+                families = [NSMutableSet set];
+            }
+            [families addObject:tableFormatFamily];
+        }
+    }
+
+    // The delegate can override the list of families to process
+    if (_delegateImplementsShouldProcessAllFormatsInFamilyForEntity) {
+        [families minusSet:[families objectsPassingTest:^BOOL(NSString *familyName, BOOL *stop) {
+            return ![_delegate imageCache:self shouldProcessAllFormatsInFamily:familyName forEntity:entity];
+        }]];
+    }
+
+    // Ensure that all formats from all of those families are included in the list
+    if (families.count) {
+        for (FICImageTable *table in _imageTables.allValues) {
+            FICImageFormat *imageFormat = table.imageFormat;
+            NSString *imageFormatName = imageFormat.name;
+            // If we're already processing this format, keep looking
+            if ([formatsToProcess containsObject:imageFormatName]) {
+                continue;
+            }
+
+            // If this format isn't included in any referenced family, keep looking
+            if (![families containsObject:imageFormat.family]) {
+                continue;
+            }
+
+            // If the image already exists, keep going
+            if ([table entryExistsForEntityUUID:entity.UUID sourceImageUUID:entity.sourceImageUUID]) {
+                continue;
+            }
+
+            [formatsToProcess addObject:imageFormatName];
+        }
+    }
+
+    return formatsToProcess;
+}
+
 #pragma mark - Checking for Image Existence
 
 - (BOOL)imageExistsForEntity:(id <FICEntity>)entity withFormatName:(NSString *)formatName {