Disk Cache: Improve handling of dirty entries.

net/disk_cache/rankings.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.
 
 // See net/disk_cache/disk_cache.h for the public interface.
 
 #ifndef NET_DISK_CACHE_RANKINGS_H_
 #define NET_DISK_CACHE_RANKINGS_H_
 #pragma once
 
@@ skipping 94 matching lines @@
   ~Rankings();
 
   bool Init(BackendImpl* backend, bool count_lists);
 
   // Restores original state, leaving the object ready for initialization.
   void Reset();
 
   // Inserts a given entry at the head of the queue.
   void Insert(CacheRankingsBlock* node, bool modified, List list);
 
-  // Removes a given entry from the LRU list.
-  void Remove(CacheRankingsBlock* node, List list);
+  // Removes a given entry from the LRU list. If |strict| is true, this method
+  // assumes that |node| is not pointed to by an active iterator. On the other
+  // hand, removing that restriction allows the current "head" of an iterator
+  // to be removed from the list (basically without control of the code that is
+  // performing the iteration), so it should be used with extra care.
+  void Remove(CacheRankingsBlock* node, List list, bool strict);
 
   // Moves a given entry to the head.
   void UpdateRank(CacheRankingsBlock* node, bool modified, List list);
 
   // Iterates through the list.
   CacheRankingsBlock* GetNext(CacheRankingsBlock* node, List list);
   CacheRankingsBlock* GetPrev(CacheRankingsBlock* node, List list);
   void FreeRankingsBlock(CacheRankingsBlock* node);
 
   // Controls tracking of nodes used for enumerations.
   void TrackRankingsBlock(CacheRankingsBlock* node, bool start_tracking);
 
   // Peforms a simple self-check of the lists, and returns the number of items
   // or an error code (negative value).
   int SelfCheck();
 
   // Returns false if the entry is clearly invalid. from_list is true if the
   // node comes from the LRU list.
-  bool SanityCheck(CacheRankingsBlock* node, bool from_list);
+  bool SanityCheck(CacheRankingsBlock* node, bool from_list) const;
+  bool DataSanityCheck(CacheRankingsBlock* node, bool from_list) const;
+
+  // Sets the |contents| field of |node| to |address|.
+  void SetContents(CacheRankingsBlock* node, CacheAddr address);
 
  private:
   typedef std::pair<CacheAddr, CacheRankingsBlock*> IteratorPair;
   typedef std::list<IteratorPair> IteratorList;
 
   void ReadHeads();
   void ReadTails();
   void WriteHead(List list);
   void WriteTail(List list);
 
@@ skipping 21 matching lines @@
 
   // Checks the links between two consecutive nodes.
   bool CheckSingleLink(CacheRankingsBlock* prev, CacheRankingsBlock* next);
 
   // Peforms a simple check of the list, and returns the number of items or an
   // error code (negative value).
   int CheckList(List list);
 
   // Returns true if addr is the head or tail of any list. When there is a
   // match |list| will contain the list number for |addr|.
-  bool IsHead(CacheAddr addr, List* list);
-  bool IsTail(CacheAddr addr, List* list);
+  bool IsHead(CacheAddr addr, List* list) const;
+  bool IsTail(CacheAddr addr, List* list) const;
 
   // Updates the iterators whenever node is being changed.
   void UpdateIterators(CacheRankingsBlock* node);
 
   // Invalidates the iterators pointing to this node.
   void InvalidateIterators(CacheRankingsBlock* node);
 
   // Keeps track of the number of entries on a list.
   void IncrementCounter(List list);
   void DecrementCounter(List list);
 
   bool init_;
   bool count_lists_;
   Addr heads_[LAST_ELEMENT];
   Addr tails_[LAST_ELEMENT];
   BackendImpl* backend_;
   LruData* control_data_;  // Data related to the LRU lists.
   IteratorList iterators_;
 
   DISALLOW_COPY_AND_ASSIGN(Rankings);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_RANKINGS_H_