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      1 // Copyright 2012 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 SYNC_INTERNAL_API_PUBLIC_READ_TRANSACTION_H_
      6 #define SYNC_INTERNAL_API_PUBLIC_READ_TRANSACTION_H_
      7 
      8 #include "base/compiler_specific.h"
      9 #include "sync/base/sync_export.h"
     10 #include "sync/internal_api/public/base_transaction.h"
     11 
     12 namespace tracked_objects {
     13 class Location;
     14 }  // namespace tracked_objects
     15 
     16 namespace sync_pb {
     17 class DataTypeContext;
     18 }
     19 
     20 namespace syncer {
     21 
     22 struct UserShare;
     23 
     24 // Sync API's ReadTransaction is a read-only BaseTransaction.  It wraps
     25 // a syncable::ReadTransaction.
     26 class SYNC_EXPORT ReadTransaction : public BaseTransaction {
     27  public:
     28   // Start a new read-only transaction on the specified repository.
     29   ReadTransaction(const tracked_objects::Location& from_here,
     30                   UserShare* share);
     31 
     32   // Resume the middle of a transaction. Will not close transaction.
     33   ReadTransaction(UserShare* share, syncable::BaseTransaction* trans);
     34 
     35   virtual ~ReadTransaction();
     36 
     37   // BaseTransaction override.
     38   virtual syncable::BaseTransaction* GetWrappedTrans() const OVERRIDE;
     39 
     40   // Return |transaction_version| of |type| stored in sync directory's
     41   // persisted info.
     42   int64 GetModelVersion(ModelType type) const;
     43 
     44   // Fills |context| with the datatype context associated with |type|.
     45   void GetDataTypeContext(ModelType type,
     46                           sync_pb::DataTypeContext* context) const;
     47 
     48  private:
     49   void* operator new(size_t size);  // Transaction is meant for stack use only.
     50 
     51   // The underlying syncable object which this class wraps.
     52   syncable::BaseTransaction* transaction_;
     53   bool close_transaction_;
     54 
     55   DISALLOW_COPY_AND_ASSIGN(ReadTransaction);
     56 };
     57 
     58 }  // namespace syncer
     59 
     60 #endif  // SYNC_INTERNAL_API_PUBLIC_READ_TRANSACTION_H_
     61