[CacheStorage] Give ownership of all CacheStorageCaches to CacheStorage

content/browser/cache_storage/cache_storage.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_H_
 #define CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 13 matching lines @@
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace storage {
 class BlobStorageContext;
 }
 
 namespace content {
 class CacheStorageScheduler;
+class CacheStorageCacheHandle;
 
 // TODO(jkarlin): Constrain the total bytes used per origin.
 
 // CacheStorage holds the set of caches for a given origin. It is
 // owned by the CacheStorageManager. This class expects to be run
 // on the IO thread. The asynchronous methods are executed serially.
 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)>
       StringsAndErrorCallback;
   using SizeCallback = base::Callback<void(int64_t)>;
 
   static const char kIndexFileName[];
 
   CacheStorage(
       const base::FilePath& origin_path,
       bool memory_only,
       base::SequencedTaskRunner* cache_task_runner,
       scoped_refptr<net::URLRequestContextGetter> request_context_getter,
       scoped_refptr<storage::QuotaManagerProxy> quota_manager_proxy,
       base::WeakPtr<storage::BlobStorageContext> blob_context,
       const GURL& origin);
 
   // Any unfinished asynchronous operations may not complete or call their
   // callbacks.
   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);
 
   // Calls the callback with whether or not the cache exists.
   void HasCache(const std::string& cache_name,
                 const BoolAndErrorCallback& callback);
 
   // Deletes the cache if it exists. If it doesn't exist,
   // CACHE_STORAGE_ERROR_NOT_FOUND is returned.
   void DeleteCache(const std::string& cache_name,
@@ skipping 21 matching lines @@
   // The size of all of the origin's contents. This value should be used as an
   // estimate only since the cache may be modified at any time.
   void Size(const SizeCallback& callback);
 
   // The functions below are for tests to verify that the operations run
   // serially.
   void StartAsyncOperationForTesting();
   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
+  // Functions for exposing handles to CacheStorageCache to clients.
+  std::unique_ptr<CacheStorageCacheHandle> CreateCacheHandle(
+      CacheStorageCache* cache);
+  void AddCacheHandleRef(CacheStorageCache* cache);
+  void DropCacheHandleRef(CacheStorageCache* cache);
+
+  // Return a CacheStorageCacheHandle for the given name if the name is known.

[nhiroki, 2016/06/14 05:30:24]

nit: s/Return/Returns/

[jkarlin, 2016/06/14 06:41:08]

Done.

+  // If the
   // CacheStorageCache has been deleted, creates a new one.

[nhiroki, 2016/06/14 05:30:24]

Can you squash this line into the previous line?

[jkarlin, 2016/06/14 06:41:08]

Done.

-  scoped_refptr<CacheStorageCache> GetLoadedCache(
+  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);
 
   // Initializer and its callback are below.
   void LazyInit();
   void LazyInitImpl();
   void LazyInitDidLoadIndex(
       std::unique_ptr<std::vector<std::string>> indexed_cache_names);
 
   // The Open and CreateCache callbacks are below.
   void OpenCacheImpl(const std::string& cache_name,
                      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,
                     const BoolAndErrorCallback& callback);
 
   // The DeleteCache callbacks are below.
   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,
                                 bool success);
   void DeleteCacheDidCleanUp(const BoolAndErrorCallback& callback,
                              bool success);
 
   // The EnumerateCache callbacks are below.
   void EnumerateCachesImpl(const StringsAndErrorCallback& callback);
 
   // The MatchCache callbacks are below.
   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,
                           std::unique_ptr<storage::BlobDataHandle> handle);
 
   // The MatchAllCaches callbacks are below.
   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,
       std::unique_ptr<ServiceWorkerResponse> service_worker_response,
       std::unique_ptr<storage::BlobDataHandle> handle);
   void MatchAllCachesDidMatchAll(
       std::unique_ptr<std::vector<CacheMatchResponse>> match_responses,
       const CacheStorageCache::ResponseCallback& callback);
 
   void GetSizeThenCloseAllCachesImpl(const SizeCallback& callback);
 
   void SizeImpl(const SizeCallback& callback);
 
   void PendingClosure(const base::Closure& callback);
   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);
   void PendingResponseCallback(
       const CacheStorageCache::ResponseCallback& callback,
       CacheStorageError error,
       std::unique_ptr<ServiceWorkerResponse> response,
       std::unique_ptr<storage::BlobDataHandle> blob_data_handle);
 
   void PendingSizeCallback(const SizeCallback& callback, int64_t size);
 
   // Whether or not we've loaded the list of cache names into memory.
   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_;
 
   // The file path for this CacheStorage.
   base::FilePath origin_path_;
 
   // The TaskRunner to run file IO on.
   scoped_refptr<base::SequencedTaskRunner> cache_task_runner_;
 
   // 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.
   scoped_refptr<storage::QuotaManagerProxy> quota_manager_proxy_;
 
   // The origin that this CacheStorage is associated with.
   GURL origin_;
 
   base::WeakPtrFactory<CacheStorage> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CacheStorage);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_CACHE_STORAGE_CACHE_STORAGE_H_