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/gtest_prod_util.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "base/strings/string_piece.h"
  16 #include "content/browser/indexed_db/leveldb/leveldb_comparator.h"
  17 #include "content/browser/indexed_db/leveldb/leveldb_database.h"
  18 #include "content/browser/indexed_db/leveldb/leveldb_iterator.h"
  19
  20 namespace content {
  21
  22 class LevelDBWriteBatch;
  23
  24 class CONTENT_EXPORT LevelDBTransaction
  25     : public base::RefCounted<LevelDBTransaction> {
  26  public:
  27   void Put(const base::StringPiece& key, std::string* value);
  28   void Remove(const base::StringPiece& key);
  29   virtual leveldb::Status Get(const base::StringPiece& key,
  30                               std::string* value,
  31                               bool* found);
  32   virtual leveldb::Status Commit();
  33   void Rollback();
  34
  35   scoped_ptr<LevelDBIterator> CreateIterator();
  36
  37  protected:
  38   virtual ~LevelDBTransaction();
  39   explicit LevelDBTransaction(LevelDBDatabase* db);
  40   friend class IndexedDBClassFactory;
  41
  42  private:
  43   friend class base::RefCounted<LevelDBTransaction>;
  44   FRIEND_TEST_ALL_PREFIXES(LevelDBDatabaseTest, Transaction);
  45   FRIEND_TEST_ALL_PREFIXES(LevelDBDatabaseTest, TransactionCommitTest);
  46   FRIEND_TEST_ALL_PREFIXES(LevelDBDatabaseTest, TransactionIterator);
  47
  48   struct Record {
  49     Record();
  50     ~Record();
  51     std::string key;
  52     std::string value;
  53     bool deleted;
  54   };
  55
  56   class Comparator {
  57    public:
  58     explicit Comparator(const LevelDBComparator* comparator)
  59         : comparator_(comparator) {}
  60     bool operator()(const base::StringPiece& a,
  61                     const base::StringPiece& b) const {
  62       return comparator_->Compare(a, b) < 0;
  63     }
  64
  65    private:
  66     const LevelDBComparator* comparator_;
  67   };
  68
  69   typedef std::map<base::StringPiece, Record*, Comparator> DataType;
  70
  71   class DataIterator : public LevelDBIterator {
  72    public:
  73     static scoped_ptr<DataIterator> Create(LevelDBTransaction* transaction);
  74     ~DataIterator() override;
  75
  76     bool IsValid() const override;
  77     leveldb::Status SeekToLast() override;
  78     leveldb::Status Seek(const base::StringPiece& slice) override;
  79     leveldb::Status Next() override;
  80     leveldb::Status Prev() override;
  81     base::StringPiece Key() const override;
  82     base::StringPiece Value() const override;
  83     bool IsDeleted() const;
  84
  85    private:
  86     explicit DataIterator(LevelDBTransaction* transaction);
  87     DataType* data_;
  88     DataType::iterator iterator_;
  89
  90     DISALLOW_COPY_AND_ASSIGN(DataIterator);
  91   };
  92
  93   class TransactionIterator : public LevelDBIterator {
  94    public:
  95     ~TransactionIterator() override;
  96     static scoped_ptr<TransactionIterator> Create(
  97         scoped_refptr<LevelDBTransaction> transaction);
  98
  99     bool IsValid() const override;
 100     leveldb::Status SeekToLast() override;
 101     leveldb::Status Seek(const base::StringPiece& target) override;
 102     leveldb::Status Next() override;
 103     leveldb::Status Prev() override;
 104     base::StringPiece Key() const override;
 105     base::StringPiece Value() const override;
 106     void DataChanged();
 107
 108    private:
 109     enum Direction { FORWARD, REVERSE };
 110
 111     explicit TransactionIterator(scoped_refptr<LevelDBTransaction> transaction);
 112     void HandleConflictsAndDeletes();
 113     void SetCurrentIteratorToSmallestKey();
 114     void SetCurrentIteratorToLargestKey();
 115     void RefreshDataIterator() const;
 116     bool DataIteratorIsLower() const;
 117     bool DataIteratorIsHigher() const;
 118
 119     scoped_refptr<LevelDBTransaction> transaction_;
 120     const LevelDBComparator* comparator_;
 121     mutable scoped_ptr<DataIterator> data_iterator_;
 122     scoped_ptr<LevelDBIterator> db_iterator_;
 123     LevelDBIterator* current_;
 124
 125     Direction direction_;
 126     mutable bool data_changed_;
 127
 128     DISALLOW_COPY_AND_ASSIGN(TransactionIterator);
 129   };
 130
 131   void Set(const base::StringPiece& key, std::string* value, bool deleted);
 132   void Clear();
 133   void RegisterIterator(TransactionIterator* iterator);
 134   void UnregisterIterator(TransactionIterator* iterator);
 135   void NotifyIterators();
 136
 137   LevelDBDatabase* db_;
 138   const LevelDBSnapshot snapshot_;
 139   const LevelDBComparator* comparator_;
 140   Comparator data_comparator_;
 141   DataType data_;
 142   bool finished_;
 143   std::set<TransactionIterator*> iterators_;
 144
 145   DISALLOW_COPY_AND_ASSIGN(LevelDBTransaction);
 146 };
 147
 148 // Reads go straight to the database, ignoring any writes cached in
 149 // write_batch_, and writes are write-through, without consolidation.
 150 class LevelDBDirectTransaction {
 151  public:
 152   static scoped_ptr<LevelDBDirectTransaction> Create(LevelDBDatabase* db);
 153
 154   ~LevelDBDirectTransaction();
 155   void Put(const base::StringPiece& key, const std::string* value);
 156   leveldb::Status Get(const base::StringPiece& key,
 157                       std::string* value,
 158                       bool* found);
 159   void Remove(const base::StringPiece& key);
 160   leveldb::Status Commit();
 161
 162  private:
 163   explicit LevelDBDirectTransaction(LevelDBDatabase* db);
 164
 165   LevelDBDatabase* db_;
 166   scoped_ptr<LevelDBWriteBatch> write_batch_;
 167   bool finished_;
 168
 169   DISALLOW_COPY_AND_ASSIGN(LevelDBDirectTransaction);
 170 };
 171
 172 }  // namespace content
 173
 174 #endif  // CONTENT_BROWSER_INDEXED_DB_LEVELDB_LEVELDB_TRANSACTION_H_