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      1 // Copyright (c) 2006-2009 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 CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
      6 #define CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
      7 #pragma once
      8 
      9 #include "chrome/browser/sync/engine/syncapi.h"
     10 #include "chrome/browser/sync/glue/sync_backend_host.h"
     11 
     12 class Profile;
     13 
     14 namespace browser_sync {
     15 
     16 class ModelAssociator;
     17 class UnrecoverableErrorHandler;
     18 
     19 // An interface used to apply changes from the sync model to the browser's
     20 // native model.  This does not currently distinguish between model data types.
     21 class ChangeProcessor {
     22  public:
     23   explicit ChangeProcessor(UnrecoverableErrorHandler* error_handler)
     24       : running_(false), error_handler_(error_handler), share_handle_(NULL) {}
     25   virtual ~ChangeProcessor();
     26 
     27   // Call when the processor should accept changes from either provided model
     28   // and apply them to the other.  Both the chrome model and sync_api are
     29   // expected to be initialized and loaded.  You must have set a valid
     30   // ModelAssociator and UnrecoverableErrorHandler before using this method,
     31   // and the two models should be associated w.r.t the ModelAssociator provided.
     32   // It is safe to call Start again after previously Stop()ing the processor.
     33   // Subclasses can extract their associated chrome model from |profile| in
     34   // |StartImpl|.
     35   void Start(Profile* profile, sync_api::UserShare* share_handle);
     36   void Stop();
     37   virtual bool IsRunning() const;
     38 
     39   // Changes have been applied to the backend model and are ready to be
     40   // applied to the frontend model. See syncapi.h for detailed instructions on
     41   // how to interpret and process |changes|.
     42   virtual void ApplyChangesFromSyncModel(
     43       const sync_api::BaseTransaction* trans,
     44       const sync_api::SyncManager::ChangeRecord* changes,
     45       int change_count) = 0;
     46 
     47   // The changes found in ApplyChangesFromSyncModel may be too slow to be
     48   // performed while holding a [Read/Write]Transaction lock. This function
     49   // is called once the lock is released and performs any slow I/O operations
     50   // without unnecessarily slowing the UI. Note that not all datatypes need
     51   // this, so we provide an empty default version.
     52   virtual void CommitChangesFromSyncModel() { }
     53 
     54  protected:
     55   // These methods are invoked by Start() and Stop() to do
     56   // implementation-specific work.
     57   virtual void StartImpl(Profile* profile) = 0;
     58   virtual void StopImpl() = 0;
     59 
     60   bool running() { return running_; }
     61   UnrecoverableErrorHandler* error_handler() { return error_handler_; }
     62   sync_api::UserShare* share_handle() { return share_handle_; }
     63 
     64  private:
     65   bool running_;  // True if we have been told it is safe to process changes.
     66   UnrecoverableErrorHandler* error_handler_;  // Guaranteed to outlive us.
     67 
     68   // The sync model we are processing changes from. Non-NULL when |running_| is
     69   // true.
     70   sync_api::UserShare* share_handle_;
     71 
     72   DISALLOW_COPY_AND_ASSIGN(ChangeProcessor);
     73 };
     74 
     75 }  // namespace browser_sync
     76 
     77 #endif  // CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
     78