From fbf14d2e163eb9a8c27bdc8983ae51a2514db977 Mon Sep 17 00:00:00 2001
From: Nebil Kriedi <nkriedi@gmail.com>
Date: Thu, 21 Feb 2013 01:07:44 +0000
Subject: [PATCH] Prefetching file properties in the disk cleaning enumerator

---
 SDWebImage/SDImageCache.m | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/SDWebImage/SDImageCache.m b/SDWebImage/SDImageCache.m
index b558e35..8a5bc61 100644
--- a/SDWebImage/SDImageCache.m
+++ b/SDWebImage/SDImageCache.m
@@ -256,14 +256,29 @@ static const NSInteger kDefaultCacheMaxCacheAge = 60 * 60 * 24 * 7; // 1 week
     dispatch_async(self.ioQueue, ^
     {
         NSDate *expirationDate = [NSDate dateWithTimeIntervalSinceNow:-self.maxCacheAge];
-        NSDirectoryEnumerator *fileEnumerator = [[NSFileManager defaultManager] enumeratorAtPath:self.diskCachePath];
-        for (NSString *fileName in fileEnumerator)
+        // convert NSString path to NSURL path
+        NSURL *diskCacheURL = [NSURL fileURLWithPath:self.diskCachePath isDirectory:YES];
+        // build an enumerator by also prefetching file properties we want to read
+        NSDirectoryEnumerator *fileEnumerator = [[NSFileManager defaultManager] enumeratorAtURL:diskCacheURL
+                                                                     includingPropertiesForKeys:@[ NSURLIsDirectoryKey, NSURLContentModificationDateKey ]
+                                                                                        options:NSDirectoryEnumerationSkipsHiddenFiles
+                                                                                   errorHandler:NULL];
+        for (NSURL *fileURL in fileEnumerator)
         {
-            NSString *filePath = [self.diskCachePath stringByAppendingPathComponent:fileName];
-            NSDictionary *attrs = [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:nil];
-            if ([[[attrs fileModificationDate] laterDate:expirationDate] isEqualToDate:expirationDate])
+            // skip folder
+            NSNumber *isDirectory;
+            [fileURL getResourceValue:&isDirectory forKey:NSURLIsDirectoryKey error:NULL];
+            if ([isDirectory boolValue])
             {
-                [[NSFileManager defaultManager] removeItemAtPath:filePath error:nil];
+                continue;
+            }
+            
+            // compare file date with the max age
+            NSDate *fileModificationDate;
+            [fileURL getResourceValue:&fileModificationDate forKey:NSURLContentModificationDateKey error:NULL];
+            if ([[fileModificationDate laterDate:expirationDate] isEqualToDate:expirationDate])
+            {
+                [[NSFileManager defaultManager] removeItemAtURL:fileURL error:nil];
             }
         }
     });