IndexedDB: Cursor pre-fetching.

content/renderer/renderer_webidbcursor_impl.h

 // Copyright (c) 2011 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_RENDERER_RENDERER_WEBIDBCURSOR_IMPL_H_
 #define CONTENT_RENDERER_RENDERER_WEBIDBCURSOR_IMPL_H_
 
+#include <deque>
+
 #include "base/basictypes.h"
 #include "content/common/indexed_db_key.h"
 #include "content/public/common/serialized_script_value.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebIDBCallbacks.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebIDBCursor.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebIDBKey.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebSerializedScriptValue.h"
 
 class RendererWebIDBCursorImpl : public WebKit::WebIDBCursor {
  public:
   RendererWebIDBCursorImpl(int32 idb_cursor_id);
   virtual ~RendererWebIDBCursorImpl();
 
   virtual unsigned short direction() const;
   virtual WebKit::WebIDBKey key() const;
   virtual WebKit::WebIDBKey primaryKey() const;
   virtual WebKit::WebSerializedScriptValue value() const;
   virtual void update(const WebKit::WebSerializedScriptValue& value,
                       WebKit::WebIDBCallbacks* callback,
                       WebKit::WebExceptionCode& ec);
   virtual void continueFunction(const WebKit::WebIDBKey& key,
                                 WebKit::WebIDBCallbacks* callback,
                                 WebKit::WebExceptionCode& ec);
   virtual void deleteFunction(WebKit::WebIDBCallbacks* callback,
                               WebKit::WebExceptionCode& ec);
+  virtual void postSuccessHandlerCallback();
 
   void SetKeyAndValue(const IndexedDBKey& key, const IndexedDBKey& primary_key,
                       const content::SerializedScriptValue& value);
+  void SetPrefetchData(
+      const std::vector<IndexedDBKey>& keys,
+      const std::vector<IndexedDBKey>& primary_keys,
+      const std::vector<content::SerializedScriptValue>& values);
+
+  void CachedContinue(WebKit::WebIDBCallbacks* callbacks);
+  void ResetPrefetchCache();
 
  private:
   int32 idb_cursor_id_;
   IndexedDBKey key_;
   IndexedDBKey primary_key_;
   content::SerializedScriptValue value_;
+
+  // Prefetch cache.
+  std::deque<IndexedDBKey> prefetch_keys_;
+  std::deque<IndexedDBKey> prefetch_primary_keys_;
+  std::deque<content::SerializedScriptValue> prefetch_values_;
+
+  // Number of continue calls that would qualify for a pre-fetch.
+  int continue_count_;
+
+  // Number of items used from the last prefetch.
+  int used_prefetches_;
+
+  // Number of onsuccess handlers we are waiting for.
+  int pending_onsuccess_callbacks_;
+
+  // Number of items to request in next prefetch.
+  int prefetch_amount_;
+
+  enum { kPrefetchContinueThreshold = 2 };
+  enum { kMinPrefetchAmount = 5 };
+  enum { kMaxPrefetchAmount = 100 };
 };
 
 #endif  // CONTENT_RENDERER_RENDERER_WEBIDBCURSOR_IMPL_H_