From 4d5326b8c59990f5a77ee43273f48487939c84e2 Mon Sep 17 00:00:00 2001
From: Richard Gravenor <rgraveno@jaguarlandrover.com>
Date: Wed, 3 Apr 2019 15:34:47 +0100
Subject: [PATCH] Retain cache hits in memory when loaded from disk

---
 AwesomeCache/Cache.swift                  | 12 ++++++++----
 AwesomeCacheTests/AwesomeCacheTests.swift | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/AwesomeCache/Cache.swift b/AwesomeCache/Cache.swift
index 6da0abd..e9b2d36 100644
--- a/AwesomeCache/Cache.swift
+++ b/AwesomeCache/Cache.swift
@@ -235,11 +235,15 @@ open class Cache<T: NSCoding> {
 
         // Otherwise, read from disk
         let path = urlForKey(key).path
-        if fileManager.fileExists(atPath: path) {
-            return _awesomeCache_unarchiveObjectSafely(path) as? CacheObject
+        guard
+            fileManager.fileExists(atPath: path),
+            let object = _awesomeCache_unarchiveObjectSafely(path) as? CacheObject  else {
+            return nil
         }
-
-        return nil
+        
+        // Keep in memory:
+        cache.setObject(object, forKey: key as NSString)
+        return object
     }
 
     // Deletes an object from disk
diff --git a/AwesomeCacheTests/AwesomeCacheTests.swift b/AwesomeCacheTests/AwesomeCacheTests.swift
index 4f450c2..a67a813 100644
--- a/AwesomeCacheTests/AwesomeCacheTests.swift
+++ b/AwesomeCacheTests/AwesomeCacheTests.swift
@@ -30,6 +30,21 @@ class AwesomeCacheTests: XCTestCase {
         XCTAssertNotNil(cache.object(forKey: "add"), "Added object should not be nil")
         XCTAssertEqual("AddedString", cache.object(forKey: "add")!, "Fetched object should be equal to the inserted object")
     }
+    
+    func testObjectIsRetainedInMemoryWhenLoadedFromDisk() {
+        let cache = try! Cache<NSString>(name: "testObjectMemoryRetention")
+        
+        //Add to cache, both in-memory and on-disk:
+        cache.setObject("AddedString", forKey: "add")
+        
+        //purge in-memory cache
+        cache.cache.removeAllObjects()
+        
+        //load from disk
+        _ = cache.object(forKey: "add")
+        
+        XCTAssertTrue(cache.isOnMemory(forKey: "add"), "Cached object should be loaded from disk and retained in memory")
+    }
 
     func testGetExpiredObjectIfPresent() {
         let cache = try! Cache<NSString>(name: "testGetExpiredObject")