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diff --git a/odb/session.hxx b/odb/session.hxx
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+++ b/odb/session.hxx
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+// file      : odb/session.hxx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009-2010 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+#ifndef ODB_SESSION_HXX
+#define ODB_SESSION_HXX
+
+#include <odb/pre.hxx>
+
+#include <map>
+#include <typeinfo>
+
+#include <odb/traits.hxx>
+#include <odb/forward.hxx>
+
+#include <odb/details/shared-ptr.hxx>
+#include <odb/details/type-info.hxx>
+
+#include <odb/details/export.hxx>
+
+namespace odb
+{
+  class LIBODB_EXPORT session
+  {
+  public:
+    typedef odb::database database_type;
+
+    // Set the current thread's session to this session. If another
+    // session is already in effect, throw the already_in_session
+    // exception.
+    //
+    session ();
+
+    // Reset the current thread's session if it is this session.
+    //
+    ~session ();
+
+    // Current session.
+    //
+  public:
+    // Return true if there is a session in effect in the current
+    // thread.
+    //
+    static bool
+    has_current ();
+
+    // Get current thread's session. Throw if no session is in effect.
+    //
+    static session&
+    current ();
+
+    // Set current thread's session.
+    //
+    static void
+    current (session&);
+
+    // Revert to the no session in effect state for the current thread.
+    //
+    static void
+    reset_current ();
+
+    // Copying or assignment of sessions is not supported.
+    //
+  private:
+    session (const session&);
+    session& operator= (const session&);
+
+  protected:
+    template <typename T>
+    struct object_pointers
+    {
+      typedef typename object_traits<T>::pointer_type pointer_type;
+      typedef typename object_traits<T>::const_pointer_type const_pointer_type;
+
+      object_pointers ();
+
+      void
+      set (const pointer_type&);
+
+      void
+      set (const const_pointer_type&);
+
+      void
+      get (pointer_type& p) const;
+
+      void
+      get (const_pointer_type& cp) const;
+
+    private:
+      pointer_type p_;
+      const_pointer_type cp_;
+    };
+
+    struct LIBODB_EXPORT object_map_base: details::shared_base
+    {
+      virtual
+      ~object_map_base ();
+    };
+
+    template <typename T>
+    struct object_map:
+      object_map_base,
+      std::map< typename object_traits<T>::id_type, object_pointers<T> >
+    {
+    };
+
+    // Object cache.
+    //
+  public:
+    template <typename T>
+    struct object_position
+    {
+      typedef typename object_traits<T>::object_type object_type;
+      typedef object_map<object_type> map;
+      typedef typename map::iterator iterator;
+
+      object_position (): map_ (0) {}
+      object_position (map& m, const iterator& p): map_ (&m), pos_ (p) {}
+
+      map* map_;
+      iterator pos_;
+    };
+
+    template <typename T>
+    object_position<T>
+    insert (database_type&,
+            const typename object_traits<T>::id_type&,
+            const typename object_traits<T>::pointer_type&);
+
+    template <typename T>
+    typename object_traits<T>::pointer_type
+    find (database_type&, const typename object_traits<T>::id_type&) const;
+
+    template <typename T>
+    void
+    erase (database_type&, const typename object_traits<T>::id_type&);
+
+    template <typename T>
+    void
+    erase (const object_position<T>&);
+
+  protected:
+    typedef std::map<const std::type_info*,
+                     details::shared_ptr<object_map_base>,
+                     details::type_info_comparator> type_map;
+
+    typedef std::map<database_type*, type_map> database_map;
+
+    database_map db_map_;
+  };
+}
+
+#include <odb/session.ixx>
+#include <odb/session.txx>
+
+#include <odb/post.hxx>
+
+#endif // ODB_SESSION_HXX