Adding DataProducer class to produce and encrypt data packets.

Change-Id: I147164a1517f1f6f24536959bc572a6d777c15b0
refs: #3016
diff --git a/src/producer-db.hpp b/src/producer-db.hpp
new file mode 100644
index 0000000..4a10d3f
--- /dev/null
+++ b/src/producer-db.hpp
@@ -0,0 +1,89 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015,  Regents of the University of California
+ *
+ * This file is part of ndn-group-encrypt (Group-based Encryption Protocol for NDN).
+ * See AUTHORS.md for complete list of ndn-group-encrypt authors and contributors.
+ *
+ * ndn-group-encrypt is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-group-encrypt is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * ndn-group-encrypt, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @author Prashanth Swaminathan <prashanthsw@gmail.com>
+ */
+
+#ifndef NDN_GEP_PRODUCER_DB_HPP
+#define NDN_GEP_PRODUCER_DB_HPP
+
+#include "common.hpp"
+
+namespace ndn {
+namespace gep {
+
+/**
+ * @brief ProducerDB is a class to manage the database of data producer.
+ * It contains one table that maps timeslots (to the nearest hour) to the
+ * content key created for that timeslot.
+ */
+class ProducerDB
+{
+public:
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : std::runtime_error(what)
+    {
+    }
+  };
+
+public:
+  explicit
+  ProducerDB(const std::string& dbPath);
+
+  ~ProducerDB();
+
+public:
+  /**
+   * @brief Check if content key exists for the hour covering @p timeslot
+   */
+  bool
+  hasContentKey(const time::system_clock::TimePoint& timeslot) const;
+
+  /**
+   * @brief Get content key for the hour covering @p timeslot
+   * @throws Error if the key does not exist
+   */
+  Buffer
+  getContentKey(const time::system_clock::TimePoint& timeslot) const;
+
+  /**
+   * @brief Add @p key as the content key for the hour covering @p timeslot
+   * @throws Error if a key for the same hour already exists
+   */
+  void
+  addContentKey(const time::system_clock::TimePoint& timeslot, const Buffer& key);
+
+  /**
+   * @brief Delete content key for the hour covering @p timeslot
+   */
+  void
+  deleteContentKey(const time::system_clock::TimePoint& timeslot);
+
+private:
+  class Impl;
+  unique_ptr<Impl> m_impl;
+};
+
+} // namespace gep
+} // namespace ndn
+
+#endif // NDN_GEP_PRODUCER_DB_HPP