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diff --git a/extras/vom/vom/singular_db.hpp b/extras/vom/vom/singular_db.hpp
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+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __VOM_INST_DB_H__
+#define __VOM_INST_DB_H__
+
+#include <map>
+#include <memory>
+#include <ostream>
+
+#include "vom/logger.hpp"
+
+namespace VOM {
+/**
+ * A Database to store the unique 'singular' instances of a single object
+ * type.
+ * The instances are stored as weak pointers. So the DB does not own these
+ * objects, they are owned by object in the client_db.
+ */
+template <typename KEY, typename OBJ>
+class singular_db
+{
+public:
+  /**
+   * Constructor
+   */
+  singular_db() {}
+
+  /**
+   * Iterator
+   */
+  typedef
+    typename std::map<KEY, std::weak_ptr<OBJ>>::const_iterator const_iterator;
+
+  /**
+   * Get iterator to the beginning of the DB
+   */
+  const_iterator begin() const { return m_map.cbegin(); }
+
+  /**
+   * Get iterator to the beginning of the DB
+   */
+  const_iterator end() const { return m_map.cend(); }
+
+  /**
+   * Find or add the object to the store.
+   * The object passed is deisred state. A new instance will be copy
+   * constructed from it. This function is templatised on the object type
+   * passed, which may be drrived from, the object type stored. this
+   * prevents slicing during the make_shared construction.
+   */
+  template <typename DERIVED>
+  std::shared_ptr<OBJ> find_or_add(const KEY& key, const DERIVED& obj)
+  {
+    auto search = m_map.find(key);
+
+    if (search == m_map.end()) {
+      std::shared_ptr<OBJ> sp = std::make_shared<DERIVED>(obj);
+
+      m_map[key] = sp;
+
+      VOM_LOG(log_level_t::DEBUG) << *sp;
+      return (sp);
+    }
+
+    return (search->second.lock());
+  }
+
+  /**
+   * Find the object to the store.
+   */
+  std::shared_ptr<OBJ> find(const KEY& key)
+  {
+    auto search = m_map.find(key);
+
+    if (search == m_map.end()) {
+      std::shared_ptr<OBJ> sp(NULL);
+
+      return (sp);
+    }
+
+    return (search->second.lock());
+  }
+
+  /**
+   * Release the object from the DB store, if it's the one we have stored
+   */
+  void release(const KEY& key, const OBJ* obj)
+  {
+    auto search = m_map.find(key);
+
+    if (search != m_map.end()) {
+      if (search->second.expired()) {
+        m_map.erase(key);
+      } else {
+        std::shared_ptr<OBJ> sp = m_map[key].lock();
+
+        if (sp.get() == obj) {
+          m_map.erase(key);
+        }
+      }
+    }
+  }
+
+  /**
+   * Find the object to the store.
+   */
+  void add(const KEY& key, std::shared_ptr<OBJ> sp) { m_map[key] = sp; }
+
+  /**
+   * Populate VPP from current state, on VPP restart
+   */
+  void replay()
+  {
+    for (auto entry : m_map) {
+      entry.second.lock()->replay();
+    }
+  }
+
+private:
+  /**
+   * the map of objects against their key
+   */
+  std::map<const KEY, std::weak_ptr<OBJ>> m_map;
+};
+};
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "mozilla")
+ * End:
+ */
+
+#endif