DOM Storage: Add renderer-process IPC code.

chrome/renderer/renderer_webstoragearea_impl.h

+// Copyright (c) 2009 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 CHROME_RENDERER_RENDERER_WEBSTORAGEAREA_IMPL_H_
+#define CHROME_RENDERER_RENDERER_WEBSTORAGEAREA_IMPL_H_
+
+#include "base/basictypes.h"
+#include "base/hash_tables.h"
+#include "base/string16.h"
+#include "webkit/api/public/WebStorageArea.h"
+#include "webkit/api/public/WebString.h"
+
+class RendererWebStorageAreaImpl : public WebKit::WebStorageArea {
+ public:
+  RendererWebStorageAreaImpl(int64 namespace_id,
+                             const WebKit::WebString& origin);
+  virtual ~RendererWebStorageAreaImpl();
+
+  // See WebStorageArea.h for documentation on these functions.
+  virtual void lock(bool& invalidate_cache, size_t& bytes_left_in_quota);
+  virtual void unlock();
+  virtual unsigned length();
+  virtual WebKit::WebString key(unsigned index, bool& key_exception);
+  virtual WebKit::WebString getItem(const WebKit::WebString& key);
+  virtual void setItem(const WebKit::WebString& key,
+                       const WebKit::WebString& value,
+                       bool& quota_exception);
+  virtual void removeItem(const WebKit::WebString& key);
+  virtual void clear();
+
+ private:
+  // Calls lock if we haven't already done so, and also gets a storage_area_id
+  // if we haven't done so.  Fetches quota and cache invalidation information
+  // while locking.  Only call on the WebKit thread.
+  void EnsureInitializedAndLocked();
+
+  // Update our quota calculation.  Returns true if we updated the quota.
+  // Returns false if we couldn't update because we would have exceeded the
+  // quota.  If an item is not in our cache, it'll require a getItem IPC in
+  // order to determine the existing value's size.
+  bool UpdateQuota(const WebKit::WebString& key,
+                   const WebKit::WebString& value);
+
+  // Set a key/value pair in our cache.
+  void SetCache(const string16& key, const WebKit::WebString& value);
+
+  // Used for initialization or storage_area_id_.
+  int64 namespace_id_;
+  string16 origin_;
+
+  // The ID we use for all IPC.  Initialized lazily.
+  int64 storage_area_id_;
+
+  // storage_area_id_ should equal this iff its unitialized.
+  static const int64 kUninitializedStorageAreaId = -1;
+
+  // Do we currently hold the lock on this storage area?
+  bool lock_held_;
+
+  // We track how many bytes are left in the quota between lock and unlock
+  // calls.  This allows us to avoid sync IPC on setItem.
+  size_t bytes_left_in_quota_;
+
+  // A cache of key/value pairs.  If the item exists, it's put in the
+  // cached_items_ map.  If not, it's added to the cached_invalid_items_ set.
+  // The lock IPC call tells us when to invalidate these caches.
+  // TODO(jorlow): Instead of a map + a set, use NullableString16 once it's
+  //               implemented: http://crbug.com/17343
+  typedef base::hash_map<string16, string16> CacheMap;
+  typedef base::hash_set<string16> CacheSet;
+  CacheMap cached_items_;
+  CacheSet cached_invalid_items_;
+};
+
+#endif  // CHROME_RENDERER_WEBSTORAGEAREA_IMPL_H_