[CacheStorage] Give ownership of all CacheStorageCaches to CacheStorage

content/browser/cache_storage/cache_storage.h

Index: content/browser/cache_storage/cache_storage.h
diff --git a/content/browser/cache_storage/cache_storage.h b/content/browser/cache_storage/cache_storage.h
index 2cea28b2cd7a281dc0f9b782e9945d1360055375..525e6167a83b2f926cdd8c55cccee66f211c5229 100644
--- a/content/browser/cache_storage/cache_storage.h
+++ b/content/browser/cache_storage/cache_storage.h
@@ -31,6 +31,7 @@ class BlobStorageContext;
 
 namespace content {
 class CacheStorageScheduler;
+class CacheStorageCacheHandle;
 
 // TODO(jkarlin): Constrain the total bytes used per origin.
 
@@ -41,7 +42,7 @@ class CONTENT_EXPORT CacheStorage {
  public:
   typedef std::vector<std::string> StringVector;
   typedef base::Callback<void(bool, CacheStorageError)> BoolAndErrorCallback;
-  typedef base::Callback<void(scoped_refptr<CacheStorageCache>,
+  typedef base::Callback<void(std::unique_ptr<CacheStorageCacheHandle>,
                               CacheStorageError)>
       CacheAndErrorCallback;
   typedef base::Callback<void(const StringVector&, CacheStorageError)>
@@ -64,7 +65,10 @@ class CONTENT_EXPORT CacheStorage {
   virtual ~CacheStorage();
 
   // Get the cache for the given key. If the cache is not found it is
-  // created.
+  // created. The CacheStorgeCacheHandle in the callback prolongs the lifetime
+  // of the cache. Once all handles to a cache are deleted the cache is deleted.
+  // The cache will also be deleted in the CacheStorage's destructor so be sure
+  // to check the handle's value before using it.
   void OpenCache(const std::string& cache_name,
                  const CacheAndErrorCallback& callback);
 
@@ -106,21 +110,31 @@ class CONTENT_EXPORT CacheStorage {
   void CompleteAsyncOperationForTesting();
 
  private:
+  friend class CacheStorageCacheHandle;
+  friend class CacheStorageCache;
   friend class TestCacheStorage;
   class CacheLoader;
   class MemoryLoader;
   class SimpleCacheLoader;
   struct CacheMatchResponse;
 
-  typedef std::map<std::string, base::WeakPtr<CacheStorageCache>> CacheMap;
+  typedef std::map<std::string, std::unique_ptr<CacheStorageCache>> CacheMap;
 
-  // Return a CacheStorageCache for the given name if the name is known. If the
-  // CacheStorageCache has been deleted, creates a new one.
-  scoped_refptr<CacheStorageCache> GetLoadedCache(
+  // Functions for exposing handles to CacheStorageCache to clients.
+  std::unique_ptr<CacheStorageCacheHandle> CreateCacheHandle(
+      CacheStorageCache* cache);
+  void AddCacheHandleRef(CacheStorageCache* cache);
+  void DropCacheHandleRef(CacheStorageCache* cache);
+
+  // Returns a CacheStorageCacheHandle for the given name if the name is known.
+  // If the CacheStorageCache has been deleted, creates a new one.
+  std::unique_ptr<CacheStorageCacheHandle> GetLoadedCache(
       const std::string& cache_name);
 
-  // Holds a reference to a cache for thirty seconds.
-  void TemporarilyPreserveCache(scoped_refptr<CacheStorageCache> cache);
+  // Holds a reference to a cache for a short period in case they're used again
+  // soon.
+  void TemporarilyPreserveCache(
+      std::unique_ptr<CacheStorageCacheHandle> cache_handle);
   virtual void SchedulePreservedCacheRemoval(
       const base::Closure& callback);  // Virtual for testing.
   void RemovePreservedCache(const CacheStorageCache* cache);
@@ -136,10 +150,11 @@ class CONTENT_EXPORT CacheStorage {
                      const CacheAndErrorCallback& callback);
   void CreateCacheDidCreateCache(const std::string& cache_name,
                                  const CacheAndErrorCallback& callback,
-                                 scoped_refptr<CacheStorageCache> cache);
-  void CreateCacheDidWriteIndex(const CacheAndErrorCallback& callback,
-                                scoped_refptr<CacheStorageCache> cache,
-                                bool success);
+                                 std::unique_ptr<CacheStorageCache> cache);
+  void CreateCacheDidWriteIndex(
+      const CacheAndErrorCallback& callback,
+      std::unique_ptr<CacheStorageCacheHandle> cache_handle,
+      bool success);
 
   // The HasCache callbacks are below.
   void HasCacheImpl(const std::string& cache_name,
@@ -149,11 +164,12 @@ class CONTENT_EXPORT CacheStorage {
   void DeleteCacheImpl(const std::string& cache_name,
                        const BoolAndErrorCallback& callback);
 
-  void DeleteCacheDidClose(const std::string& cache_name,
-                           const BoolAndErrorCallback& callback,
-                           const StringVector& ordered_cache_names,
-                           scoped_refptr<CacheStorageCache> cache,
-                           int64_t cache_size);
+  void DeleteCacheDidClose(
+      const std::string& cache_name,
+      const BoolAndErrorCallback& callback,
+      const StringVector& ordered_cache_names,
+      std::unique_ptr<CacheStorageCacheHandle> cache_handle,
+      int64_t cache_size);
   void DeleteCacheDidWriteIndex(const std::string& cache_name,
                                 const BoolAndErrorCallback& callback,
                                 int cache_size,
@@ -168,7 +184,7 @@ class CONTENT_EXPORT CacheStorage {
   void MatchCacheImpl(const std::string& cache_name,
                       std::unique_ptr<ServiceWorkerFetchRequest> request,
                       const CacheStorageCache::ResponseCallback& callback);
-  void MatchCacheDidMatch(scoped_refptr<CacheStorageCache> cache,
+  void MatchCacheDidMatch(std::unique_ptr<CacheStorageCacheHandle> cache_handle,
                           const CacheStorageCache::ResponseCallback& callback,
                           CacheStorageError error,
                           std::unique_ptr<ServiceWorkerResponse> response,
@@ -178,7 +194,7 @@ class CONTENT_EXPORT CacheStorage {
   void MatchAllCachesImpl(std::unique_ptr<ServiceWorkerFetchRequest> request,
                           const CacheStorageCache::ResponseCallback& callback);
   void MatchAllCachesDidMatch(
-      scoped_refptr<CacheStorageCache> cache,
+      std::unique_ptr<CacheStorageCacheHandle> cache_handle,
       CacheMatchResponse* out_match_response,
       const base::Closure& barrier_closure,
       CacheStorageError error,
@@ -196,9 +212,10 @@ class CONTENT_EXPORT CacheStorage {
   void PendingBoolAndErrorCallback(const BoolAndErrorCallback& callback,
                                    bool found,
                                    CacheStorageError error);
-  void PendingCacheAndErrorCallback(const CacheAndErrorCallback& callback,
-                                    scoped_refptr<CacheStorageCache> cache,
-                                    CacheStorageError error);
+  void PendingCacheAndErrorCallback(
+      const CacheAndErrorCallback& callback,
+      std::unique_ptr<CacheStorageCacheHandle> cache_handle,
+      CacheStorageError error);
   void PendingStringsAndErrorCallback(const StringsAndErrorCallback& callback,
                                       const StringVector& strings,
                                       CacheStorageError error);
@@ -214,12 +231,23 @@ class CONTENT_EXPORT CacheStorage {
   bool initialized_;
   bool initializing_;
 
+  // True if the backend is supposed to reside in memory only.
+  bool memory_only_;
+
   // The pending operation scheduler.
   std::unique_ptr<CacheStorageScheduler> scheduler_;
 
   // The map of cache names to CacheStorageCache objects.
   CacheMap cache_map_;
 
+  // Caches that have been deleted but must still be held onto until all handles
+  // have been released.
+  std::map<CacheStorageCache*, std::unique_ptr<CacheStorageCache>>
+      deleted_caches_;
+
+  // CacheStorageCacheHandle reference counts
+  std::map<CacheStorageCache*, size_t> cache_handle_counts_;
+
   // The names of caches in the order that they were created.
   StringVector ordered_cache_names_;
 
@@ -232,9 +260,9 @@ class CONTENT_EXPORT CacheStorage {
   // Performs backend specific operations (memory vs disk).
   std::unique_ptr<CacheLoader> cache_loader_;
 
-  // Holds ref pointers to recently opened caches so that they can be reused
-  // without having the open the cache again.
-  std::map<const CacheStorageCache*, scoped_refptr<CacheStorageCache>>
+  // Holds handles to recently opened caches so that they can be reused
+  // without having to open the cache again.
+  std::map<const CacheStorageCache*, std::unique_ptr<CacheStorageCacheHandle>>
       preserved_caches_;
 
   // The quota manager.