content/browser/indexed_db/leveldb/leveldb_transaction.h

   1 // Copyright (c) 2013 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 CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_
   6 #define CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11
  12 #include "base/memory/ref_counted.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/strings/string_piece.h"
  15 #include "content/browser/indexed_db/leveldb/leveldb_comparator.h"
  16 #include "content/browser/indexed_db/leveldb/leveldb_database.h"
  17 #include "content/browser/indexed_db/leveldb/leveldb_iterator.h"
  18
  19 namespace content {
  20
  21 class LevelDBWriteBatch;
  22
  23 class CONTENT_EXPORT LevelDBTransaction
  24     : public base::RefCounted<LevelDBTransaction> {
  25  public:
  26   explicit LevelDBTransaction(LevelDBDatabase* db);
  27
  28   void Put(const base::StringPiece& key, std::string* value);
  29   void Remove(const base::StringPiece& key);
  30   bool Get(const base::StringPiece& key, std::string* value, bool* found);
  31   bool Commit();
  32   void Rollback();
  33
  34   scoped_ptr<LevelDBIterator> CreateIterator();
  35
  36  private:
  37   virtual ~LevelDBTransaction();
  38   friend class base::RefCounted<LevelDBTransaction>;
  39
  40   struct Record {
  41     Record();
  42     ~Record();
  43     std::string key;
  44     std::string value;
  45     bool deleted;
  46   };
  47
  48   class Comparator {
  49    public:
  50     explicit Comparator(const LevelDBComparator* comparator)
  51         : comparator_(comparator) {}
  52     bool operator()(const base::StringPiece& a,
  53                     const base::StringPiece& b) const {
  54       return comparator_->Compare(a, b) < 0;
  55     }
  56
  57    private:
  58     const LevelDBComparator* comparator_;
  59   };
  60
  61   typedef std::map<base::StringPiece, Record*, Comparator> DataType;
  62
  63   class DataIterator : public LevelDBIterator {
  64    public:
  65     static scoped_ptr<DataIterator> Create(LevelDBTransaction* transaction);
  66     virtual ~DataIterator();
  67
  68     virtual bool IsValid() const OVERRIDE;
  69     virtual void SeekToLast() OVERRIDE;
  70     virtual void Seek(const base::StringPiece& slice) OVERRIDE;
  71     virtual void Next() OVERRIDE;
  72     virtual void Prev() OVERRIDE;
  73     virtual base::StringPiece Key() const OVERRIDE;
  74     virtual base::StringPiece Value() const OVERRIDE;
  75     bool IsDeleted() const;
  76
  77    private:
  78     explicit DataIterator(LevelDBTransaction* transaction);
  79     DataType* data_;
  80     DataType::iterator iterator_;
  81   };
  82
  83   class TransactionIterator : public LevelDBIterator {
  84    public:
  85     virtual ~TransactionIterator();
  86     static scoped_ptr<TransactionIterator> Create(
  87         scoped_refptr<LevelDBTransaction> transaction);
  88
  89     virtual bool IsValid() const OVERRIDE;
  90     virtual void SeekToLast() OVERRIDE;
  91     virtual void Seek(const base::StringPiece& target) OVERRIDE;
  92     virtual void Next() OVERRIDE;
  93     virtual void Prev() OVERRIDE;
  94     virtual base::StringPiece Key() const OVERRIDE;
  95     virtual base::StringPiece Value() const OVERRIDE;
  96     void DataChanged();
  97
  98    private:
  99     explicit TransactionIterator(scoped_refptr<LevelDBTransaction> transaction);
 100     void HandleConflictsAndDeletes();
 101     void SetCurrentIteratorToSmallestKey();
 102     void SetCurrentIteratorToLargestKey();
 103     void RefreshDataIterator() const;
 104     bool DataIteratorIsLower() const;
 105     bool DataIteratorIsHigher() const;
 106
 107     scoped_refptr<LevelDBTransaction> transaction_;
 108     const LevelDBComparator* comparator_;
 109     mutable scoped_ptr<DataIterator> data_iterator_;
 110     scoped_ptr<LevelDBIterator> db_iterator_;
 111     LevelDBIterator* current_;
 112
 113     enum Direction {
 114       FORWARD,
 115       REVERSE
 116     };
 117     Direction direction_;
 118     mutable bool data_changed_;
 119   };
 120
 121   void Set(const base::StringPiece& key, std::string* value, bool deleted);
 122   void Clear();
 123   void RegisterIterator(TransactionIterator* iterator);
 124   void UnregisterIterator(TransactionIterator* iterator);
 125   void NotifyIterators();
 126
 127   LevelDBDatabase* db_;
 128   const LevelDBSnapshot snapshot_;
 129   const LevelDBComparator* comparator_;
 130   Comparator data_comparator_;
 131   DataType data_;
 132   bool finished_;
 133   std::set<TransactionIterator*> iterators_;
 134 };
 135
 136 class LevelDBWriteOnlyTransaction {
 137  public:
 138   static scoped_ptr<LevelDBWriteOnlyTransaction> Create(LevelDBDatabase* db);
 139
 140   ~LevelDBWriteOnlyTransaction();
 141   void Remove(const base::StringPiece& key);
 142   bool Commit();
 143
 144  private:
 145   explicit LevelDBWriteOnlyTransaction(LevelDBDatabase* db);
 146
 147   LevelDBDatabase* db_;
 148   scoped_ptr<LevelDBWriteBatch> write_batch_;
 149   bool finished_;
 150 };
 151
 152 }  // namespace content
 153
 154 #endif  // CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_