IndexedDB: Switch key/value handling from vector<char> to std::string

content/browser/indexed_db/leveldb/leveldb_transaction.h

 // Copyright (c) 2013 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_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_
 #define CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/strings/string_piece.h"
 #include "content/browser/indexed_db/leveldb/avltree.h"
 #include "content/browser/indexed_db/leveldb/leveldb_comparator.h"
 #include "content/browser/indexed_db/leveldb/leveldb_database.h"
 #include "content/browser/indexed_db/leveldb/leveldb_iterator.h"
-#include "content/browser/indexed_db/leveldb/leveldb_slice.h"
 
 namespace content {
 
 class LevelDBWriteBatch;
 
 class CONTENT_EXPORT LevelDBTransaction
     : public base::RefCounted<LevelDBTransaction> {
  public:
   static scoped_refptr<LevelDBTransaction> Create(LevelDBDatabase* db);
 
-  void Put(const LevelDBSlice& key, std::vector<char>* value);
-  void Remove(const LevelDBSlice& key);
-  bool Get(const LevelDBSlice& key, std::string* value, bool* found);
+  void Put(const base::StringPiece& key, std::string* value);
+  void Remove(const base::StringPiece& key);
+  bool Get(const base::StringPiece& key, std::string* value, bool* found);
   bool Commit();
   void Rollback();
 
   scoped_ptr<LevelDBIterator> CreateIterator();
 
  private:
   explicit LevelDBTransaction(LevelDBDatabase* db);
   virtual ~LevelDBTransaction();
   friend class base::RefCounted<LevelDBTransaction>;
 
   struct AVLTreeNode {
     AVLTreeNode();
     ~AVLTreeNode();
-    std::vector<char> key;
-    std::vector<char> value;
+    std::string key;
+    std::string value;
     bool deleted;
 
     AVLTreeNode* less;
     AVLTreeNode* greater;
     int balance_factor;
     DISALLOW_COPY_AND_ASSIGN(AVLTreeNode);
   };
 
   struct AVLTreeAbstractor {
     typedef AVLTreeNode* handle;
     typedef size_t size;
-    typedef LevelDBSlice key;
+    typedef base::StringPiece key;
 
     handle GetLess(handle h) { return h->less; }
     void SetLess(handle h, handle less) { h->less = less; }
     handle GetGreater(handle h) { return h->greater; }
     void SetGreater(handle h, handle greater) { h->greater = greater; }
 
     int GetBalanceFactor(handle h) { return h->balance_factor; }
     void SetBalanceFactor(handle h, int bf) { h->balance_factor = bf; }
 
     int CompareKeyKey(const key& ka, const key& kb) {
       return comparator_->Compare(ka, kb);
     }
+
+    static key make_key(const std::string& vector) {
+      if (vector.empty())
+        return key();
+      return key(&*vector.begin(), vector.size());
+    }
     int CompareKeyNode(const key& k, handle h) {
-      return CompareKeyKey(k, key(h->key));
+      return CompareKeyKey(k, make_key(h->key));
     }
     int CompareNodeNode(handle ha, handle hb) {
-      return CompareKeyKey(key(ha->key), key(hb->key));
+      return CompareKeyKey(make_key(ha->key), make_key(hb->key));
     }
 
     static handle Null() { return 0; }
 
     const LevelDBComparator* comparator_;
   };
 
   typedef AVLTree<AVLTreeAbstractor> TreeType;
 
   class TreeIterator : public LevelDBIterator {
    public:
     static scoped_ptr<TreeIterator> Create(LevelDBTransaction* transaction);
     virtual ~TreeIterator();
 
     virtual bool IsValid() const OVERRIDE;
     virtual void SeekToLast() OVERRIDE;
-    virtual void Seek(const LevelDBSlice& slice) OVERRIDE;
+    virtual void Seek(const base::StringPiece& slice) OVERRIDE;
     virtual void Next() OVERRIDE;
     virtual void Prev() OVERRIDE;
-    virtual LevelDBSlice Key() const OVERRIDE;
-    virtual LevelDBSlice Value() const OVERRIDE;
+    virtual base::StringPiece Key() const OVERRIDE;
+    virtual base::StringPiece Value() const OVERRIDE;
     bool IsDeleted() const;
     void Reset();
 
    private:
     explicit TreeIterator(LevelDBTransaction* transaction);
     mutable TreeType::Iterator iterator_;  // Dereferencing this is non-const.
     TreeType* tree_;
     LevelDBTransaction* transaction_;
-    std::vector<char> key_;
+    std::string key_;
   };
 
   class TransactionIterator : public LevelDBIterator {
    public:
     virtual ~TransactionIterator();
     static scoped_ptr<TransactionIterator> Create(
         scoped_refptr<LevelDBTransaction> transaction);
 
     virtual bool IsValid() const OVERRIDE;
     virtual void SeekToLast() OVERRIDE;
-    virtual void Seek(const LevelDBSlice& target) OVERRIDE;
+    virtual void Seek(const base::StringPiece& target) OVERRIDE;
     virtual void Next() OVERRIDE;
     virtual void Prev() OVERRIDE;
-    virtual LevelDBSlice Key() const OVERRIDE;
-    virtual LevelDBSlice Value() const OVERRIDE;
+    virtual base::StringPiece Key() const OVERRIDE;
+    virtual base::StringPiece Value() const OVERRIDE;
     void TreeChanged();
 
    private:
     explicit TransactionIterator(scoped_refptr<LevelDBTransaction> transaction);
     void HandleConflictsAndDeletes();
     void SetCurrentIteratorToSmallestKey();
     void SetCurrentIteratorToLargestKey();
     void RefreshTreeIterator() const;
     bool TreeIteratorIsLower() const;
     bool TreeIteratorIsHigher() const;
 
     scoped_refptr<LevelDBTransaction> transaction_;
     const LevelDBComparator* comparator_;
     mutable scoped_ptr<TreeIterator> tree_iterator_;
     scoped_ptr<LevelDBIterator> db_iterator_;
     LevelDBIterator* current_;
 
     enum Direction {
       FORWARD,
       REVERSE
     };
     Direction direction_;
     mutable bool tree_changed_;
   };
 
-  void Set(const LevelDBSlice& key,
-           std::vector<char>* value,
-           bool deleted);
+  void Set(const base::StringPiece& key, std::string* value, bool deleted);
   void ClearTree();
   void RegisterIterator(TransactionIterator* iterator);
   void UnregisterIterator(TransactionIterator* iterator);
   void NotifyIteratorsOfTreeChange();
 
   LevelDBDatabase* db_;
   const LevelDBSnapshot snapshot_;
   const LevelDBComparator* comparator_;
   TreeType tree_;
   bool finished_;
   std::set<TransactionIterator*> iterators_;
 };
 
 class LevelDBWriteOnlyTransaction {
  public:
   static scoped_ptr<LevelDBWriteOnlyTransaction> Create(LevelDBDatabase* db);
 
   ~LevelDBWriteOnlyTransaction();
-  void Remove(const LevelDBSlice& key);
+  void Remove(const base::StringPiece& key);
   bool Commit();
 
  private:
   explicit LevelDBWriteOnlyTransaction(LevelDBDatabase* db);
 
   LevelDBDatabase* db_;
   scoped_ptr<LevelDBWriteBatch> write_batch_;
   bool finished_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_