[3681] DataSource class added.

- code refactoring after last commit, clean-up, compilation fixes
 - Makefile updates
 - Added new unit-tests for DataSource (mostly moved from LeaseMgr
   unit-tests)

src/lib/dhcpsrv/mysql_lease_mgr.h

@@ -28,57 +28,9 @@
 namespace isc {
 namespace dhcp {
 
-/// @brief MySQL Handle Holder
-///
-/// Small RAII object for safer initialization, will close the database
-/// connection upon destruction.  This means that if an exception is thrown
-/// during database initialization, resources allocated to the database are
-/// guaranteed to be freed.
-///
-/// It makes no sense to copy an object of this class.  After the copy, both
-/// objects would contain pointers to the same MySql context object.  The
-/// destruction of one would invalidate the context in the remaining object.
-/// For this reason, the class is declared noncopyable.
-class MySqlHolder : public boost::noncopyable {
-public:
-
-    /// @brief Constructor
-    ///
-    /// Initialize MySql and store the associated context object.
-    ///
-    /// @throw DbOpenError Unable to initialize MySql handle.
-    MySqlHolder() : mysql_(mysql_init(NULL)) {
-        if (mysql_ == NULL) {
-            isc_throw(DbOpenError, "unable to initialize MySQL");
-        }
-    }
-
-    /// @brief Destructor
-    ///
-    /// Frees up resources allocated by the initialization of MySql.
-    ~MySqlHolder() {
-        if (mysql_ != NULL) {
-            mysql_close(mysql_);
-        }
-        // The library itself shouldn't be needed anymore
-        mysql_library_end();
-    }
-
-    /// @brief Conversion Operator
-    ///
-    /// Allows the MySqlHolder object to be passed as the context argument to
-    /// mysql_xxx functions.
-    operator MYSQL*() const {
-        return (mysql_);
-    }
-
-private:
-    MYSQL* mysql_;      ///< Initialization context
-};
-
 // Define the current database schema values
 
-const uint32_t CURRENT_VERSION_VERSION = 2;
+const uint32_t CURRENT_VERSION_VERSION = 3;
 const uint32_t CURRENT_VERSION_MINOR = 0;
 
 
@@ -356,6 +308,54 @@ public:
     ///        failed.
     virtual bool deleteLease(const isc::asiolink::IOAddress& addr);
 
+    /// @brief Return backend type
+    ///
+    /// Returns the type of the backend (e.g. "mysql", "memfile" etc.)
+    ///
+    /// @return Type of the backend.
+    virtual std::string getType() const {
+        return (std::string("mysql"));
+    }
+
+    /// @brief Returns backend name.
+    ///
+    /// Each backend have specific name, e.g. "mysql" or "sqlite".
+    ///
+    /// @return Name of the backend.
+    virtual std::string getName() const;
+
+    /// @brief Returns description of the backend.
+    ///
+    /// This description may be multiline text that describes the backend.
+    ///
+    /// @return Description of the backend.
+    virtual std::string getDescription() const;
+
+    /// @brief Returns backend version.
+    ///
+    /// @return Version number as a pair of unsigned integers.  "first" is the
+    ///         major version number, "second" the minor number.
+    ///
+    /// @throw isc::dhcp::DbOperationError An operation on the open database has
+    ///        failed.
+    virtual std::pair<uint32_t, uint32_t> getVersion() const;
+
+    /// @brief Commit Transactions
+    ///
+    /// Commits all pending database operations.  On databases that don't
+    /// support transactions, this is a no-op.
+    ///
+    /// @throw DbOperationError Iif the commit failed.
+    virtual void commit();
+
+    /// @brief Rollback Transactions
+    ///
+    /// Rolls back all pending database operations.  On databases that don't
+    /// support transactions, this is a no-op.
+    ///
+    /// @throw DbOperationError If the rollback failed.
+    virtual void rollback();
+
     ///@{
     /// The following methods are used to convert between times and time
     /// intervals stored in the Lease object, and the times stored in the
@@ -409,7 +409,27 @@ public:
                                  uint32_t valid_lifetime, time_t& cltt);
     ///@}
 
-
+    /// @brief Statement Tags
+    ///
+    /// The contents of the enum are indexes into the list of SQL statements
+    enum StatementIndex {
+        DELETE_LEASE4,              // Delete from lease4 by address
+        DELETE_LEASE6,              // Delete from lease6 by address
+        GET_LEASE4_ADDR,            // Get lease4 by address
+        GET_LEASE4_CLIENTID,        // Get lease4 by client ID
+        GET_LEASE4_CLIENTID_SUBID,  // Get lease4 by client ID & subnet ID
+        GET_LEASE4_HWADDR,          // Get lease4 by HW address
+        GET_LEASE4_HWADDR_SUBID,    // Get lease4 by HW address & subnet ID
+        GET_LEASE6_ADDR,            // Get lease6 by address
+        GET_LEASE6_DUID_IAID,       // Get lease6 by DUID and IAID
+        GET_LEASE6_DUID_IAID_SUBID, // Get lease6 by DUID, IAID and subnet ID
+        GET_VERSION,                // Obtain version number
+        INSERT_LEASE4,              // Add entry to lease4 table
+        INSERT_LEASE6,              // Add entry to lease6 table
+        UPDATE_LEASE4,              // Update a Lease4 entry
+        UPDATE_LEASE6,              // Update a Lease6 entry
+        NUM_STATEMENTS              // Number of statements
+    };
 
 private: