sync: move ChangeProcessor from glue/ to components/sync_driver

BUG=339726

Review URL: https://codereview.chromium.org/237303005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@264610 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 88 insertions, 0 deletions

diff --git a/components/sync_driver/change_processor.h b/components/sync_driver/change_processor.h
new file mode 100644
index 0000000..efefea9
--- /dev/null
+++ b/components/sync_driver/change_processor.h
@@ -0,0 +1,88 @@
+// Copyright 2014 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 COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_
+#define COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_
+
+#include "components/sync_driver/data_type_error_handler.h"
+#include "sync/internal_api/public/base_transaction.h"
+#include "sync/internal_api/public/change_record.h"
+#include "sync/internal_api/public/user_share.h"
+
+namespace syncer {
+class UnrecoverableErrorHandler;
+}  // namespace syncer
+
+namespace browser_sync {
+
+class ModelAssociator;
+
+// An interface used to apply changes from the sync model to the browser's
+// native model.  This does not currently distinguish between model data types.
+class ChangeProcessor {
+ public:
+  explicit ChangeProcessor(DataTypeErrorHandler* error_handler);
+  virtual ~ChangeProcessor();
+
+  // Call when the processor should accept changes from either provided model
+  // and apply them to the other.  Both the native model and sync_api are
+  // expected to be initialized and loaded.  You must have set a valid
+  // ModelAssociator and UnrecoverableErrorHandler before using this method, and
+  // the two models should be associated w.r.t the ModelAssociator provided.
+  void Start(syncer::UserShare* share_handle);
+
+  // Changes have been applied to the backend model and are ready to be
+  // applied to the frontend model.
+  virtual void ApplyChangesFromSyncModel(
+      const syncer::BaseTransaction* trans,
+      int64 model_version,
+      const syncer::ImmutableChangeRecordList& changes) = 0;
+
+  // The changes found in ApplyChangesFromSyncModel may be too slow to be
+  // performed while holding a [Read/Write]Transaction lock or may interact
+  // with another thread, which might itself be waiting on the transaction lock,
+  // putting us at risk of deadlock.
+  // This function is called once the transactional lock is released and it is
+  // safe to perform inter-thread or slow I/O operations. Note that not all
+  // datatypes need this, so we provide an empty default version.
+  virtual void CommitChangesFromSyncModel();
+
+  // This ensures that startobserving gets called after stopobserving even
+  // if there is an early return in the function.
+  template <class T>
+  class ScopedStopObserving {
+   public:
+    explicit ScopedStopObserving(T* processor)
+        : processor_(processor) {
+      processor_->StopObserving();
+    }
+    ~ScopedStopObserving() {
+      processor_->StartObserving();
+    }
+
+   private:
+    ScopedStopObserving() {}
+    T* processor_;
+  };
+
+ protected:
+  // These methods are invoked by Start() and Stop() to do
+  // implementation-specific work.
+  virtual void StartImpl() = 0;
+
+  DataTypeErrorHandler* error_handler() const;
+  virtual syncer::UserShare* share_handle() const;
+
+ private:
+  DataTypeErrorHandler* error_handler_;  // Guaranteed to outlive us.
+
+  // The sync model we are processing changes from.
+  syncer::UserShare* share_handle_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChangeProcessor);
+};
+
+}  // namespace browser_sync
+
+#endif  // COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_