extensions/browser/api/storage/value_store_cache.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef EXTENSIONS_BROWSER_API_STORAGE_VALUE_STORE_CACHE_H_
   6 #define EXTENSIONS_BROWSER_API_STORAGE_VALUE_STORE_CACHE_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "base/memory/ref_counted.h"
  12
  13 class ValueStore;
  14
  15 namespace extensions {
  16
  17 class Extension;
  18
  19 // Each namespace of the storage API implements this interface.
  20 // Instances are created on the UI thread, but from then on live on the FILE
  21 // thread. At shutdown, ShutdownOnUI() is first invoked on the UI thread, and
  22 // the destructor is invoked soon after on the FILE thread. This gives
  23 // implementations the chance to work with ValueStores on FILE but observe
  24 // events on UI.
  25 // It also means that any methods invoked on UI *before ShutdownOnUI()* can
  26 // safely post other methods to the FILE thread, since the deletion task is only
  27 // posted to FILE after ShutdownOnUI().
  28 class ValueStoreCache {
  29  public:
  30   typedef base::Callback<void(ValueStore*)> StorageCallback;
  31
  32   // Invoked on FILE.
  33   virtual ~ValueStoreCache();
  34
  35   // This is invoked from the UI thread during destruction of the Profile that
  36   // ultimately owns this object. Any Profile-related cleanups should be
  37   // performed in this method, since the destructor will execute later, after
  38   // the Profile is already gone.
  39   virtual void ShutdownOnUI();
  40
  41   // Requests the cache to invoke |callback| with the appropriate ValueStore
  42   // for the given |extension|. |callback| should be invoked with a NULL
  43   // ValueStore in case of errors.
  44   // |extension| is passed in a scoped_refptr<> because this method is
  45   // asynchronously posted as a task to the loop returned by GetMessageLoop(),
  46   // and this guarantees the Extension is still valid when the method executes.
  47   virtual void RunWithValueStoreForExtension(
  48       const StorageCallback& callback,
  49       scoped_refptr<const Extension> extension) = 0;
  50
  51   // Requests the cache to delete any storage used by |extension_id|.
  52   virtual void DeleteStorageSoon(const std::string& extension_id) = 0;
  53 };
  54
  55 }  // namespace extensions
  56
  57 #endif  // EXTENSIONS_BROWSER_API_STORAGE_VALUE_STORE_CACHE_H_