[IndexedDB] Propogating changes to observers : Renderer

content/browser/indexed_db/indexed_db_observer_changes.h

+// Copyright 2016 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.
+
+// This class holds all observed operations of a transaction corresponding to a
+// single connection.
+
+#ifndef CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_OBSERVER_CHANGES_H_
+#define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_OBSERVER_CHANGES_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/stl_util.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+class IndexedDBObservation;
+
+class CONTENT_EXPORT IndexedDBObserverChanges {
+ public:
+  IndexedDBObserverChanges();
+  ~IndexedDBObserverChanges();
+
+  void RecordObserverForLastObservation(int32_t observer_id);
+  void AddObservation(std::unique_ptr<IndexedDBObservation> observation);
+
+  std::map<int32_t, std::vector<int32_t>>& observation_index() {

[Marijn Kruisselbrink, 2016/07/11 23:10:39]

Would it make sense to instead of having methods that return non-const
references have methods that either return by const reference (if that is needed
anywhere) and a different method that move-returns by value? The move-returning
method can then have a more explicit name that makes it clear that
IndexedDBObserverChanges state is being changed (something like
release_observations())

[palakj1, 2016/07/13 00:43:51]

Done.

+    return observation_index_;
+  }
+  std::vector<std::unique_ptr<IndexedDBObservation>>& observations() {
+    return observations_;
+  }
+
+ private:
+  // Maps observer_id to corresponding set of indices in observations.
+  std::map<int32_t, std::vector<int32_t>> observation_index_;

[Marijn Kruisselbrink, 2016/07/11 23:10:39]

Is observation_index really the best name for this concept? It seems that at
least it should be observation_indices_, as it stores a list of indices for each
observer...

[palakj1, 2016/07/13 00:43:51]

Agreed. Changed to observation_indices_map. Any better suggestions?

+  std::vector<std::unique_ptr<IndexedDBObservation>> observations_;
+
+  DISALLOW_COPY_AND_ASSIGN(IndexedDBObserverChanges);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_OBSERVER_CHANGES_H_