Implement support for optimistic concurrency

New pragmas: optimistic, version. New test: optimistic. New database
function: reload().

14 files changed, 716 insertions, 102 deletions

diff --git a/odb/context.cxx b/odb/context.cxx
index f1386d2..2e96ba9 100644
--- a/odb/context.cxx
+++ b/odb/context.cxx
@@ -1096,6 +1096,8 @@ namespace
         c_.inverse++;
       else if (context::readonly (member_path_, member_scope_))
         c_.readonly++;
+      else if (context::version (m))
+        c_.optimistic_managed++;
     }
 
     context::column_count_type c_;
diff --git a/odb/context.hxx b/odb/context.hxx
index d1a9073..10210a3 100644
--- a/odb/context.hxx
+++ b/odb/context.hxx
@@ -398,12 +398,32 @@ public:
     return c.count ("readonly");
   }
 
+  //
+  //
   bool
   null (semantics::data_member&);
 
   bool
   null (semantics::data_member&, string const& key_prefix);
 
+  // Optimistic concurrency.
+  //
+  static semantics::data_member*
+  optimistic (semantics::class_& c)
+  {
+    // Set by the validator.
+    //
+    return c.get<semantics::data_member*> ("optimistic-member", 0);
+  }
+
+  static bool
+  version (semantics::data_member& m)
+  {
+    return m.count ("version");
+  }
+
+  //
+  //
   typedef ::class_kind class_kind_type;
 
   static class_kind_type
@@ -490,12 +510,20 @@ public:
 public:
   struct column_count_type
   {
-    column_count_type (): total (0), id (0), inverse (0), readonly (0) {}
+    column_count_type ()
+        : total (0),
+          id (0),
+          inverse (0),
+          readonly (0),
+          optimistic_managed (0)
+    {
+    }
 
     size_t total;
     size_t id;
     size_t inverse;
     size_t readonly;
+    size_t optimistic_managed;
   };
 
   static column_count_type
diff --git a/odb/pragma.cxx b/odb/pragma.cxx
index eee2677..585da42 100644
--- a/odb/pragma.cxx
+++ b/odb/pragma.cxx
@@ -316,7 +316,8 @@ check_spec_decl_type (tree d,
   else if (p == "auto" ||
            p == "column" ||
            p == "inverse" ||
-           p == "transient")
+           p == "transient" ||
+           p == "version")
   {
     if (tc != FIELD_DECL)
     {
@@ -341,7 +342,8 @@ check_spec_decl_type (tree d,
            p == "abstract" ||
            p == "callback" ||
            p == "query" ||
-           p == "object")
+           p == "object" ||
+           p == "optimistic")
   {
     if (tc != RECORD_TYPE)
     {
@@ -689,6 +691,18 @@ handle_pragma (cpp_reader* reader,
 
     tt = pragma_lex (&t);
   }
+  else if (p == "optimistic")
+  {
+    // optimistic
+    //
+
+    // Make sure we've got the correct declaration type.
+    //
+    if (decl != 0 && !check_spec_decl_type (decl, decl_name, p, loc))
+      return;
+
+    tt = pragma_lex (&t);
+  }
   else if (p == "callback")
   {
     // callback (name)
@@ -1460,7 +1474,7 @@ handle_pragma (cpp_reader* reader,
   }
   else if (p == "readonly")
   {
-    // transient
+    // readonly
     //
 
     // Make sure we've got the correct declaration type.
@@ -1482,6 +1496,18 @@ handle_pragma (cpp_reader* reader,
 
     tt = pragma_lex (&t);
   }
+  else if (p == "version")
+  {
+    // version
+    //
+
+    // Make sure we've got the correct declaration type.
+    //
+    if (decl != 0 && !check_spec_decl_type (decl, decl_name, p, loc))
+      return;
+
+    tt = pragma_lex (&t);
+  }
   else
   {
     error () << "unknown db pragma " << p << endl;
@@ -1629,7 +1655,8 @@ handle_pragma_qualifier (cpp_reader* reader, string const& p)
            p == "inverse" ||
            p == "unordered" ||
            p == "readonly" ||
-           p == "transient")
+           p == "transient" ||
+           p == "version")
   {
     handle_pragma (reader, p, "member", 0, "");
     return;
@@ -1853,6 +1880,12 @@ handle_pragma_db_transient (cpp_reader* r)
 }
 
 extern "C" void
+handle_pragma_db_version (cpp_reader* r)
+{
+  handle_pragma_qualifier (r, "version");
+}
+
+extern "C" void
 handle_pragma_db (cpp_reader* r)
 {
   tree t;
@@ -1915,5 +1948,6 @@ register_odb_pragmas (void*, void*)
   c_register_pragma_with_expansion ("db", "unordered", handle_pragma_db_unordered);
   c_register_pragma_with_expansion ("db", "readonly", handle_pragma_db_readonly);
   c_register_pragma_with_expansion ("db", "transient", handle_pragma_db_transient);
+  c_register_pragma_with_expansion ("db", "version", handle_pragma_db_version);
   */
 }
diff --git a/odb/relational/header.hxx b/odb/relational/header.hxx
index 355ec83..39f2bbf 100644
--- a/odb/relational/header.hxx
+++ b/odb/relational/header.hxx
@@ -892,6 +892,7 @@ namespace relational
 
       class1 ()
           : id_image_member_ ("id_"),
+            version_image_member_ ("version_"),
             query_columns_type_ (false),
             pointer_query_columns_type_ (true)
       {
@@ -901,6 +902,7 @@ namespace relational
           : root_context (), //@@ -Wextra
             context (),
             id_image_member_ ("id_"),
+            version_image_member_ ("version_"),
             query_columns_type_ (false),
             pointer_query_columns_type_ (true)
       {
@@ -940,6 +942,8 @@ namespace relational
         bool auto_id (id ? id->count ("auto") : false);
         bool base_id (id ? &id->scope () != &c : false); // Comes from base.
 
+        semantics::data_member* optimistic (context::optimistic (c));
+
         column_count_type const& cc (column_count (c));
 
         os << "// " << c.name () << endl
@@ -992,8 +996,13 @@ namespace relational
           {
             string const& base (id->scope ().fq_name ());
 
-            os << "typedef object_traits< " << base << " >::id_type id_type;"
-               << endl
+            os << "typedef object_traits< " << base << " >::id_type id_type;";
+
+            if (optimistic != 0)
+              os << "typedef object_traits< " << base << " >::version_type " <<
+                "version_type;";
+
+            os << endl
                << "static const bool auto_id = object_traits< " << base <<
               " >::auto_id;"
                << endl
@@ -1003,13 +1012,23 @@ namespace relational
           }
           else
           {
-            semantics::names* hint;
-            semantics::type& t (utype (*id, hint));
+            {
+              semantics::names* hint;
+              semantics::type& t (utype (*id, hint));
 
-            os << "typedef " << t.fq_name (hint) << " id_type;"
-               << endl;
+              os << "typedef " << t.fq_name (hint) << " id_type;";
+            }
+
+            if (optimistic != 0)
+            {
+              semantics::names* hint;
+              semantics::type& t (utype (*optimistic, hint));
+
+              os << "typedef " << t.fq_name (hint) << " version_type;";
+            }
 
-            os << "static const bool auto_id = " <<
+            os << endl
+               << "static const bool auto_id = " <<
               (auto_id ? "true" : "false") << ";"
                << endl;
 
@@ -1018,6 +1037,9 @@ namespace relational
 
             id_image_member_->traverse (*id);
 
+            if (optimistic != 0)
+              version_image_member_->traverse (*optimistic);
+
             os << "std::size_t version;"
                << "};";
           }
@@ -1054,7 +1076,8 @@ namespace relational
         if (id != 0 || !abstract)
           // We want to generate a dummy void id() accessor even if this
           // object has no id to help us in the runtime. This way we can
-          // generic code that will both for both void and non-void ids.
+          // write generic code that will work for both void and non-void
+          // ids.
           //
           os << "static id_type" << endl
              << "id (const object_type&);"
@@ -1065,6 +1088,11 @@ namespace relational
              << "id (const image_type&);"
              << endl;
 
+        if (id != 0 && optimistic != 0)
+          os << "static version_type" << endl
+             << "version (const image_type&);"
+             << endl;
+
         // grow ()
         //
         if (generate_grow)
@@ -1108,7 +1136,8 @@ namespace relational
         if (id != 0)
         {
           os << "static void" << endl
-             << "init (id_image_type&, const id_type&);"
+             << "init (id_image_type&, const id_type&" <<
+            (optimistic != 0 ? ", const version_type* = 0" : "") << ");"
              << endl;
         }
 
@@ -1156,6 +1185,8 @@ namespace relational
           cc.inverse << "UL;"
            << "static const std::size_t readonly_column_count = " <<
           cc.readonly << "UL;"
+           << "static const std::size_t managed_optimistic_column_count = " <<
+          cc.optimistic_managed << "UL;"
            << endl;
 
         // Statements.
@@ -1170,6 +1201,9 @@ namespace relational
             os << "static const char update_statement[];";
 
           os << "static const char erase_statement[];";
+
+          if (optimistic != 0)
+            os << "static const char optimistic_erase_statement[];";
         }
 
         if (options.generate_query ())
@@ -1216,6 +1250,10 @@ namespace relational
              << "find (database&, const id_type&, object_type&);"
              << endl;
 
+          os << "static bool" << endl
+             << "reload (database&, object_type&);"
+             << endl;
+
           // update ()
           //
           if (!readonly (c))
@@ -1228,6 +1266,10 @@ namespace relational
           os << "static void" << endl
              << "erase (database&, const id_type&);"
              << endl;
+
+          os << "static void" << endl
+             << "erase (database&, const object_type&);"
+             << endl;
         }
 
         // query ()
@@ -1560,6 +1602,7 @@ namespace relational
     private:
       instance<image_type> image_type_;
       instance<image_member> id_image_member_;
+      instance<image_member> version_image_member_;
 
       instance<query_columns_type> query_columns_type_;
       instance<query_columns_type> pointer_query_columns_type_;
diff --git a/odb/relational/inline.hxx b/odb/relational/inline.hxx
index 3968dce..0c37d33 100644
--- a/odb/relational/inline.hxx
+++ b/odb/relational/inline.hxx
@@ -109,6 +109,8 @@ namespace relational
         semantics::data_member* id (id_member (c));
         bool base_id (id ? &id->scope () != &c : false); // Comes from base.
 
+        semantics::data_member* optimistic (context::optimistic (c));
+
         os << "// " << c.name () << endl
            << "//" << endl
            << endl;
@@ -139,10 +141,10 @@ namespace relational
 
         if (id != 0)
         {
+          // id (image_type)
+          //
           if (options.generate_query () && base_id)
           {
-            // id (image_type)
-            //
             os << "inline" << endl
                << traits << "::id_type" << endl
                << traits << "::" << endl
@@ -153,6 +155,20 @@ namespace relational
                << "}";
           }
 
+          // version (image_type)
+          //
+          if (optimistic != 0 && base_id)
+          {
+            os << "inline" << endl
+               << traits << "::version_type" << endl
+               << traits << "::" << endl
+               << "version (const image_type& i)"
+               << "{"
+               << "return object_traits< " <<
+              optimistic->scope ().fq_name () << " >::version (i);"
+               << "}";
+          }
+
           // bind (id_image_type)
           //
           if (base_id)
@@ -170,10 +186,11 @@ namespace relational
           {
             os << "inline" << endl
                << "void " << traits << "::" << endl
-               << "init (id_image_type& i, const id_type& id)"
+               << "init (id_image_type& i, const id_type& id" <<
+              (optimistic != 0 ? ", const version_type* v" : "") << ")"
                << "{"
                << "object_traits< " << id->scope ().fq_name () <<
-              " >::init (i, id);"
+              " >::init (i, id" << (optimistic != 0 ? ", v" : "") << ");"
                << "}";
           }
         }
@@ -184,6 +201,18 @@ namespace relational
         if (abstract)
           return;
 
+        // erase (object_type)
+        //
+        if (id != 0 && optimistic == 0)
+        {
+          os << "inline" << endl
+             << "void " << traits << "::" << endl
+             << "erase (database& db, const object_type& obj)"
+             << "{"
+             << "erase (db, id (obj));"
+             << "}";
+        }
+
         // callback ()
         //
         os << "inline" << endl
diff --git a/odb/relational/mysql/source.cxx b/odb/relational/mysql/source.cxx
index d49910f..6a05878 100644
--- a/odb/relational/mysql/source.cxx
+++ b/odb/relational/mysql/source.cxx
@@ -197,7 +197,7 @@ namespace relational
             os << "// " << mi.m.name () << endl
                << "//" << endl;
 
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               os << "if (sk == statement_select)"
                  << "{";
             // If the whole class is readonly, then we will never be
@@ -242,7 +242,7 @@ namespace relational
                    << "sk == statement_select ? 0 : ";
 
                 if (cc.inverse != 0)
-                  os << cc.inverse << "UL" << endl;
+                  os << cc.inverse << "UL";
 
                 if (!ro && cc.readonly != 0)
                 {
@@ -266,7 +266,7 @@ namespace relational
 
             // The same logic as in pre().
             //
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               block = true;
             else if (!readonly (*context::top_object))
             {
@@ -587,6 +587,12 @@ namespace relational
             member = member_override_;
           else
           {
+            // If we are generating standard init() and this member
+            // contains version, ignore it.
+            //
+            if (version (mi.m))
+              return false;
+
             string const& name (mi.m.name ());
             member = "o." + name;
 
diff --git a/odb/relational/oracle/source.cxx b/odb/relational/oracle/source.cxx
index 62b417b..0c40bab 100644
--- a/odb/relational/oracle/source.cxx
+++ b/odb/relational/oracle/source.cxx
@@ -90,7 +90,7 @@ namespace relational
             os << "// " << mi.m.name () << endl
                << "//" << endl;
 
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               os << "if (sk == statement_select)"
                  << "{";
             // If the whole class is readonly, then we will never be
@@ -135,7 +135,7 @@ namespace relational
                    << "sk == statement_select ? 0 : ";
 
                 if (cc.inverse != 0)
-                  os << cc.inverse << "UL" << endl;
+                  os << cc.inverse << "UL";
 
                 if (!ro && cc.readonly != 0)
                 {
@@ -159,7 +159,7 @@ namespace relational
 
             // The same logic as in pre().
             //
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               block = true;
             else if (!readonly (*context::top_object))
             {
@@ -335,6 +335,12 @@ namespace relational
             member = member_override_;
           else
           {
+            // If we are generating standard init() and this member
+            // contains version, ignore it.
+            //
+            if (version (mi.m))
+              return false;
+
             string const& name (mi.m.name ());
             member = "o." + name;
 
diff --git a/odb/relational/pgsql/header.cxx b/odb/relational/pgsql/header.cxx
index 474b69c..db7a939 100644
--- a/odb/relational/pgsql/header.cxx
+++ b/odb/relational/pgsql/header.cxx
@@ -26,17 +26,27 @@ namespace relational
           if (abstract (c))
             return;
 
+          semantics::data_member* id (id_member (c));
+          semantics::data_member* optimistic (context::optimistic (c));
+
           column_count_type const& cc (column_count (c));
 
           // Statement names.
           //
-          os << "static const char persist_statement_name[];"
-             << "static const char find_statement_name[];";
+          os << "static const char persist_statement_name[];";
+
+          if (id != 0)
+          {
+            os << "static const char find_statement_name[];";
 
-          if (cc.total != cc.id + cc.inverse + cc.readonly)
-            os << "static const char update_statement_name[];";
+            if (cc.total != cc.id + cc.inverse + cc.readonly)
+              os << "static const char update_statement_name[];";
 
-          os << "static const char erase_statement_name[];";
+            os << "static const char erase_statement_name[];";
+
+            if (optimistic != 0)
+              os << "static const char optimistic_erase_statement_name[];";
+          }
 
           // Query statement name.
           //
@@ -48,14 +58,23 @@ namespace relational
 
           // Statement types.
           //
-          os << "static const unsigned int persist_statement_types[];"
-             << "static const unsigned int find_statement_types[];";
+          os << "static const unsigned int persist_statement_types[];";
 
-          if (cc.total != cc.id + cc.inverse + cc.readonly)
-            os << "static const unsigned int update_statement_types[];";
+          if (id != 0)
+          {
+            os << "static const unsigned int find_statement_types[];";
 
-          os << "static const unsigned int erase_statement_types[];"
-             << endl;
+            if (cc.total != cc.id + cc.inverse + cc.readonly)
+              os << "static const unsigned int update_statement_types[];";
+
+            os << "static const unsigned int erase_statement_types[];";
+
+            if (optimistic != 0)
+              os << "static const unsigned int " <<
+                "optimistic_erase_statement_types[];";
+          }
+
+          os << endl;
         }
 
         virtual void
diff --git a/odb/relational/pgsql/source.cxx b/odb/relational/pgsql/source.cxx
index 6bfa3d9..0ff0bf1 100644
--- a/odb/relational/pgsql/source.cxx
+++ b/odb/relational/pgsql/source.cxx
@@ -122,6 +122,10 @@ namespace relational
               sk_ == statement_update)
             return false;
 
+          if ((sk_ == statement_insert || sk_ == statement_update) &&
+              version (m))
+            return false;
+
           if (!first)
             os << ',' << endl;
 
@@ -164,7 +168,7 @@ namespace relational
             os << "// " << mi.m.name () << endl
                << "//" << endl;
 
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               os << "if (sk == statement_select)"
                  << "{";
             // If the whole class is readonly, then we will never be
@@ -209,7 +213,7 @@ namespace relational
                    << "sk == statement_select ? 0 : ";
 
                 if (cc.inverse != 0)
-                  os << cc.inverse << "UL" << endl;
+                  os << cc.inverse << "UL";
 
                 if (!ro && cc.readonly != 0)
                 {
@@ -233,7 +237,7 @@ namespace relational
 
             // The same logic as in pre().
             //
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               block = true;
             else if (!readonly (*context::top_object))
             {
@@ -493,6 +497,12 @@ namespace relational
             member = member_override_;
           else
           {
+            // If we are generating standard init() and this member
+            // contains version, ignore it.
+            //
+            if (version (mi.m))
+              return false;
+
             string const& name (mi.m.name ());
             member = "o." + name;
 
@@ -1001,6 +1011,7 @@ namespace relational
             return;
 
           semantics::data_member* id (id_member (c));
+          semantics::data_member* optimistic (context::optimistic (c));
           column_count_type const& cc (column_count (c));
 
           string const& n (c.fq_name ());
@@ -1028,6 +1039,12 @@ namespace relational
             os << name_decl << endl
                << "erase_statement_name[] = " << strlit (fn + "_erase") << ";"
                << endl;
+
+            if (optimistic != 0)
+              os << name_decl << endl
+                 << "optimistic_erase_statement_name[] = " <<
+                strlit (fn + "_optimistic_erase") << ";"
+                 << endl;
           }
 
           // Query statement name.
@@ -1087,9 +1104,18 @@ namespace relational
               st->traverse (c);
             }
 
+            bool first (cc.total == cc.id + cc.inverse + cc.readonly +
+                        cc.optimistic_managed);
+
             {
               instance<statement_oids> st (statement_where);
-              st->traverse_column (*id, "", false);
+              st->traverse_column (*id, "", first);
+            }
+
+            if (optimistic != 0)
+            {
+              instance<statement_oids> st (statement_where);
+              st->traverse_column (*optimistic, "", false);
             }
 
             os << "};";
@@ -1108,6 +1134,25 @@ namespace relational
 
             os << "};";
           }
+
+          if (id != 0 && optimistic != 0)
+          {
+            os << oid_decl << endl
+               << "optimistic_erase_statement_types[] ="
+               << "{";
+
+            {
+              instance<statement_oids> st (statement_where);
+              st->traverse_column (*id, "", true);
+            }
+
+            {
+              instance<statement_oids> st (statement_where);
+              st->traverse_column (*optimistic, "", false);
+            }
+
+            os << "};";
+          }
         }
 
         virtual void
diff --git a/odb/relational/source.hxx b/odb/relational/source.hxx
index dcc9c23..cabb5c5 100644
--- a/odb/relational/source.hxx
+++ b/odb/relational/source.hxx
@@ -90,6 +90,17 @@ namespace relational
 
         line_.clear ();
 
+        // Version column (optimistic concurrency) requires special
+        // handling in the UPDATE statement.
+        //
+        //
+        if (sk_ == statement_update && version (m))
+        {
+          string const& qname (quote_id (name));
+          line_ = qname + "=" + qname + "+1";
+          return true;
+        }
+
         // Inverse object pointers come from a joined table.
         //
         if (im != 0)
@@ -565,20 +576,22 @@ namespace relational
         os << "n += " << cc.total << "UL";
 
         // select = total
-        // insert = total - inverse
-        // update = total - inverse - id - readonly
+        // insert = total - inverse - optimistic_managed
+        // update = total - inverse - optimistic_managed - id - readonly
         //
-        if (cc.inverse != 0 || (!ro && (cc.id != 0 || cc.readonly != 0)))
+        if (cc.inverse != 0 ||
+            cc.optimistic_managed != 0 ||
+            (!ro && (cc.id != 0 || cc.readonly != 0)))
         {
           os << " - (" << endl
              << "sk == statement_select ? 0 : ";
 
-          if (cc.inverse != 0)
-            os << cc.inverse << "UL" << endl;
+          if (cc.inverse != 0 || cc.optimistic_managed != 0)
+            os << (cc.inverse + cc.optimistic_managed) << "UL";
 
           if (!ro && (cc.id != 0 || cc.readonly != 0))
           {
-            if (cc.inverse != 0)
+            if (cc.inverse != 0 || cc.optimistic_managed != 0)
               os << " + ";
 
             os << "(" << endl
@@ -2085,7 +2098,9 @@ namespace relational
           if (count_++ != 0)
             params_ += ',';
 
-          if (m.count ("id") && m.count ("auto"))
+          if (version (m))
+            params_ += "1";
+          else if (m.count ("id") && m.count ("auto"))
             params_ += qp_.auto_id ();
           else
             params_ += qp_.next ();
@@ -2112,8 +2127,11 @@ namespace relational
           : grow_base_ (index_),
             grow_member_ (index_),
             bind_id_member_ ("id_"),
+            bind_version_member_ ("version_"),
             init_id_image_member_ ("id_", "id"),
+            init_version_image_member_ ("version_", "(*v)"),
             init_id_value_member_ ("id"),
+            init_version_value_member_ ("v"),
             stream_ (emitter_),
             drop_model_ (emitter_, stream_, format_embedded),
             drop_table_ (emitter_, stream_, format_embedded),
@@ -2131,8 +2149,11 @@ namespace relational
             grow_base_ (index_),
             grow_member_ (index_),
             bind_id_member_ ("id_"),
+            bind_version_member_ ("version_"),
             init_id_image_member_ ("id_", "id"),
+            init_version_image_member_ ("version_", "(*v)"),
             init_id_value_member_ ("id"),
+            init_version_value_member_ ("v"),
             stream_ (emitter_),
             drop_model_ (emitter_, stream_, format_embedded),
             drop_table_ (emitter_, stream_, format_embedded),
@@ -2266,13 +2287,16 @@ namespace relational
         bool auto_id (id ? id->count ("auto") : false);
         bool base_id (id ? &id->scope () != &c : false); // Comes from base.
 
+        semantics::data_member* optimistic (context::optimistic (c));
+
         bool grow (false);
         bool grow_id (false);
 
         if (generate_grow)
         {
           grow = context::grow (c);
-          grow_id = id ? context::grow (*id) : false;
+          grow_id = (id ? context::grow (*id) : false) ||
+            (optimistic ? context::grow (*optimistic) : false);
         }
 
         column_count_type const& cc (column_count (c));
@@ -2345,6 +2369,18 @@ namespace relational
              << "}";
         }
 
+        if (id != 0 && optimistic != 0 && !base_id)
+        {
+          os << traits << "::version_type" << endl
+             << traits << "::" << endl
+             << "version (const image_type& i)"
+             << "{"
+             << "version_type v;";
+          init_version_value_member_->traverse (*optimistic);
+          os << "return v;"
+             << "}";
+        }
+
         // grow ()
         //
         if (generate_grow)
@@ -2397,7 +2433,17 @@ namespace relational
              << "bind (" << bind_vector << " b, id_image_type& i)"
              << "{"
              << "std::size_t n (0);";
+
           bind_id_member_->traverse (*id);
+
+          if (optimistic != 0)
+          {
+            os << "n++;" //@@ composite id
+               << endl;
+
+            bind_version_member_->traverse (*optimistic);
+          }
+
           os << "}";
         }
 
@@ -2449,17 +2495,27 @@ namespace relational
         if (id != 0 && !base_id)
         {
           os << "void " << traits << "::" << endl
-             << "init (id_image_type& i, const id_type& id)"
+             << "init (id_image_type& i, const id_type& id" <<
+            (optimistic != 0 ? ", const version_type* v" : "") << ")"
              << "{";
 
           if (grow_id)
-            os << "bool grew (false);";
+            os << "bool grew (false);"
+               << endl;
 
           init_id_image_member_->traverse (*id);
 
+          if (optimistic != 0)
+          {
+            // Here we rely on the fact that init_image_member
+            // always wraps the statements in a block.
+            //
+            os << "if (v != 0)";
+            init_version_image_member_->traverse (*optimistic);
+          }
+
           if (grow_id)
-            os << endl
-               << "if (grew)" << endl
+            os << "if (grew)" << endl
                << "i.version++;";
 
           os << "}";
@@ -2564,7 +2620,13 @@ namespace relational
             instance<object_columns> t (statement_update, true, qp.get ());
             t->traverse (c);
 
-            os << strlit (" WHERE " + id_col + "=" + qp->next ()) << ";"
+            string where (" WHERE " + id_col + "=" + qp->next ());
+
+            if (optimistic != 0)
+              where += " AND " + column_qname (*optimistic) + "=" +
+                qp->next ();
+
+            os << strlit (where) << ";"
                << endl;
           }
 
@@ -2577,6 +2639,20 @@ namespace relational
                << strlit (" WHERE " + id_col + "=" + qp->next ()) << ";"
                << endl;
           }
+
+          if (optimistic != 0)
+          {
+            instance<query_parameters> qp;
+
+            string where (" WHERE " + id_col + "=" + qp->next ());
+            where += " AND " + column_qname (*optimistic) + "=" + qp->next ();
+
+            os << "const char " << traits <<
+              "::optimistic_erase_statement[] =" << endl
+               << strlit ("DELETE FROM " + table) << endl
+               << strlit (where) << ";"
+               << endl;
+          }
         }
 
         if (options.generate_query ())
@@ -2678,6 +2754,19 @@ namespace relational
              << endl;
         }
 
+        if (optimistic != 0)
+        {
+          // Set the version in the object member.
+          //
+          if (!auto_id || const_type (optimistic->type ()))
+            os << "const_cast< version_type& > (" <<
+              "obj." << optimistic->name () << ") = 1;";
+          else
+            os << "obj." << optimistic->name () << " = 1;";
+
+          os << endl;
+        }
+
         if (straight_containers)
         {
           // Initialize id_image and binding.
@@ -2718,9 +2807,15 @@ namespace relational
           {
             // Initialize object and id images.
             //
-            os << "id_image_type& i (sts.id_image ());"
-               << "init (i, obj." << id->name () << ");"
-               << endl
+            os << "id_image_type& i (sts.id_image ());";
+
+            if (optimistic == 0)
+              os << "init (i, obj." << id->name () << ");";
+            else
+              os << "init (i, obj." << id->name () << ", &obj." <<
+                optimistic->name () << ");";
+
+            os << endl
                << "image_type& im (sts.image ());"
                << "if (init (im, obj, statement_update))" << endl
                << "im.version++;"
@@ -2748,18 +2843,33 @@ namespace relational
                << "if (i.version != sts.update_id_image_version () || " <<
               "idb.version == 0)"
                << "{"
+              // If the id binding is up-to-date, then that means update
+              // binding is too and we just need to update the versions.
+              //
+               << "if (i.version != sts.id_image_version () || " <<
+              "idb.version == 0)"
+               << "{"
                << "bind (idb.bind, i);"
-               << "sts.update_id_image_version (i.version);"
-               << "if (!u)" << endl
-               << "imb.version++;"
-               << endl
-              // Update the id binding versions since we rebound it.
+              // Update the id binding versions since we may use them later
+              // to update containers.
               //
                << "sts.id_image_version (i.version);"
                << "idb.version++;"
+               << "}"
+               << "sts.update_id_image_version (i.version);"
+               << endl
+               << "if (!u)" << endl
+               << "imb.version++;"
                << "}";
 
-            os << "sts.update_statement ().execute ();";
+            os << "if (sts.update_statement ().execute () == 0)" << endl;
+
+            if (optimistic == 0)
+              os << "throw object_not_persistent ();";
+            else
+              os << "throw object_changed ();";
+
+            os << endl;
           }
           else
           {
@@ -2772,20 +2882,28 @@ namespace relational
 
             if (straight_readwrite_containers)
               os << endl
-                 << "binding& idb (sts.id_image_binding ());";
+                 << "binding& idb (sts.id_image_binding ());"
+                 << endl;
           }
 
           if (straight_readwrite_containers)
           {
-            os << endl;
             instance<container_calls> t (container_calls::update_call);
             t->traverse (c);
           }
 
+          if (optimistic != 0)
+          {
+            // Update version in the object member.
+            //
+            os << "const_cast< version_type& > (" <<
+              "obj." << optimistic->name () << ")++;";
+          }
+
           os << "}";
         }
 
-        // erase ()
+        // erase (id_type)
         //
         if (id != 0)
         {
@@ -2823,7 +2941,6 @@ namespace relational
           {
             instance<container_calls> t (container_calls::erase_call);
             t->traverse (c);
-            os << endl;
           }
 
           os << "if (sts.erase_statement ().execute () != 1)" << endl
@@ -2832,6 +2949,91 @@ namespace relational
           os << "}";
         }
 
+        // erase (object_type)
+        //
+        if (id != 0 && optimistic != 0)
+        {
+          os << "void " << traits << "::" << endl
+             << "erase (database&, const object_type& obj)"
+             << "{"
+             << "using namespace " << db << ";"
+             << endl
+             << db << "::connection& conn (" << endl
+             << db << "::transaction::current ().connection ());"
+             << object_statements_type << "& sts (" << endl
+             << "conn.statement_cache ().find_object<object_type> ());"
+             << endl;
+
+          // Initialize id + managed column image.
+          //
+          os << "id_image_type& i (sts.id_image ());"
+             << "init (i, obj." << id->name () << ", &obj." <<
+            optimistic->name () << ");"
+             << endl;
+
+          // To update the id part of the optimistic id binding we have
+          // to do it indirectly via the id binding, since both id and
+          // optimistic id bindings just point to the suffix of the
+          // update bind array (see object_statements).
+          //
+          os << "binding& idb (sts.id_image_binding ());"
+             << "binding& oidb (sts.optimistic_id_image_binding ());"
+             << "if (i.version != sts.optimistic_id_image_version () || " <<
+            "oidb.version == 0)"
+             << "{"
+            // If the id binding is up-to-date, then that means optimistic
+            // id binding is too and we just need to update the versions.
+            //
+             << "if (i.version != sts.id_image_version () || idb.version == 0)"
+             << "{"
+             << "bind (idb.bind, i);"
+            // Update the id binding versions since we may use them later
+            // to delete containers.
+            //
+             << "sts.id_image_version (i.version);"
+             << "idb.version++;"
+             << "}"
+             << "sts.optimistic_id_image_version (i.version);"
+             << "oidb.version++;"
+             << "}";
+
+          // Erase containers first so that there are no reference
+          // violations (we don't want to rely on ON DELETE CASCADE
+          // here since in case of a custom schema, it might not be
+          // there).
+          //
+          if (straight_containers)
+          {
+            // Things get complicated here: we don't want to trash the
+            // containers and then find out that the versions don't match
+            // and we therefore cannot delete the object. After all, there
+            // is no guarantee that the user will abort the transaction.
+            // In fact, a perfectly reasonable scenario is to reload the
+            // object, re-apply the changes, and commit the transaction.
+            //
+            // There doesn't seem to be anything better than first making
+            // sure we can delete the object, then deleting the container
+            // data, and then deleting the object. To check that we can
+            // delete the object we are going to use find_() and then
+            // compare the versions. A special-purpose SELECT query would
+            // have been more efficient but it would complicated and bloat
+            // things significantly.
+            //
+            os << "if (!find_ (sts, obj." << id->name () << ") ||" << endl
+               << "version (sts.image ()) != obj." << optimistic->name () <<
+              ")" << endl
+               << "throw object_changed ();"
+               << endl;
+
+            instance<container_calls> t (container_calls::erase_call);
+            t->traverse (c);
+          }
+
+          os << "if (sts.optimistic_erase_statement ().execute () != 1)" << endl
+             << "throw object_changed ();"
+             << "}";
+        }
+
         // find (id)
         //
         if (id != 0 && c.default_ctor ())
@@ -2895,18 +3097,18 @@ namespace relational
              << db << "::transaction::current ().connection ());"
              << object_statements_type << "& sts (" << endl
              << "conn.statement_cache ().find_object<object_type> ());"
-             << object_statements_type << "::auto_lock l (sts);"
              << endl
-             << "if (l.locked ())"
-             << "{"
-             << "if (!find_ (sts, id))" << endl
+            // This can only be top-level call so auto_lock must succeed.
+            //
+             << object_statements_type << "::auto_lock l (sts);"
+             << endl;
+
+          os << "if (!find_ (sts, id))" << endl
              << "return false;"
-             << "}"
+             << endl
              << "reference_cache_traits< object_type >::insert_guard ig (" << endl
              << "reference_cache_traits< object_type >::insert (db, id, obj));"
              << endl
-             << "if (l.locked ())"
-             << "{"
              << "callback (db, obj, callback_event::pre_load);"
              << "init (obj, sts.image (), db);";
 
@@ -2916,12 +3118,49 @@ namespace relational
              << "sts.load_delayed ();"
              << "l.unlock ();"
              << "callback (db, obj, callback_event::post_load);"
-             << "}"
-             << "else" << endl
-             << "sts.delay_load (id, obj, ig.position ());"
+             << "ig.release ();"
+             << "return true;"
+             << "}";
+        }
+
+        // reload()
+        //
+        if (id != 0)
+        {
+          os << "bool " << traits << "::" << endl
+             << "reload (database& db, object_type& obj)"
+             << "{"
+             << "using namespace " << db << ";"
+             << endl
+             << db << "::connection& conn (" << endl
+             << db << "::transaction::current ().connection ());"
+             << object_statements_type << "& sts (" << endl
+             << "conn.statement_cache ().find_object<object_type> ());"
+             << endl
+            // This can only be top-level call so auto_lock must succeed.
+            //
+             << object_statements_type << "::auto_lock l (sts);"
              << endl;
 
-          os << "ig.release ();"
+          os << "if (!find_ (sts, obj." << id->name () << "))" << endl
+             << "return false;"
+             << endl;
+
+          if (optimistic != 0)
+            os << "if (version (sts.image ()) == obj." <<
+              optimistic->name () << ")" << endl
+               << "return true;"
+               << endl;
+
+          os << "callback (db, obj, callback_event::pre_load);"
+             << "init (obj, sts.image (), db);";
+
+          init_value_extra ();
+
+          os << "load_ (sts, obj);"
+             << "sts.load_delayed ();"
+             << "l.unlock ();"
+             << "callback (db, obj, callback_event::post_load);"
              << "return true;"
              << "}";
         }
@@ -4126,6 +4365,7 @@ namespace relational
       instance<bind_member> bind_member_;
       traversal::names bind_member_names_;
       instance<bind_member> bind_id_member_;
+      instance<bind_member> bind_version_member_;
 
       instance<init_image_base> init_image_base_;
       traversal::inherits init_image_base_inherits_;
@@ -4133,12 +4373,15 @@ namespace relational
       traversal::names init_image_member_names_;
 
       instance<init_image_member> init_id_image_member_;
+      instance<init_image_member> init_version_image_member_;
 
       instance<init_value_base> init_value_base_;
       traversal::inherits init_value_base_inherits_;
       instance<init_value_member> init_value_member_;
       traversal::names init_value_member_names_;
+
       instance<init_value_member> init_id_value_member_;
+      instance<init_value_member> init_version_value_member_;
 
       schema_emitter emitter_;
       emitter_ostream stream_;
diff --git a/odb/relational/sqlite/source.cxx b/odb/relational/sqlite/source.cxx
index 0516370..041f8aa 100644
--- a/odb/relational/sqlite/source.cxx
+++ b/odb/relational/sqlite/source.cxx
@@ -48,7 +48,7 @@ namespace relational
             os << "// " << mi.m.name () << endl
                << "//" << endl;
 
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               os << "if (sk == statement_select)"
                  << "{";
             // If the whole class is readonly, then we will never be
@@ -93,7 +93,7 @@ namespace relational
                    << "sk == statement_select ? 0 : ";
 
                 if (cc.inverse != 0)
-                  os << cc.inverse << "UL" << endl;
+                  os << cc.inverse << "UL";
 
                 if (!ro && cc.readonly != 0)
                 {
@@ -117,7 +117,7 @@ namespace relational
 
             // The same logic as in pre().
             //
-            if (inverse (mi.m, key_prefix_))
+            if (inverse (mi.m, key_prefix_) || version (mi.m))
               block = true;
             else if (!readonly (*context::top_object))
             {
@@ -295,6 +295,12 @@ namespace relational
             member = member_override_;
           else
           {
+            // If we are generating standard init() and this member
+            // contains version, ignore it.
+            //
+            if (version (mi.m))
+              return false;
+
             string const& name (mi.m.name ());
             member = "o." + name;
 
diff --git a/odb/tracer/header.cxx b/odb/tracer/header.cxx
index 5ba6c95..f4a3a72 100644
--- a/odb/tracer/header.cxx
+++ b/odb/tracer/header.cxx
@@ -77,12 +77,18 @@ namespace tracer
            << "update (database&, const object_type&);"
            << endl;
 
-        // erase ()
+        // erase (id_type)
         //
         os << "static void" << endl
            << "erase (database&, const id_type&);"
            << endl;
 
+        // erase (object_type)
+        //
+        os << "static void" << endl
+           << "erase (database&, const object_type&);"
+           << endl;
+
         // find ()
         //
         os << "static pointer_type" << endl
diff --git a/odb/tracer/source.cxx b/odb/tracer/source.cxx
index 8412714..5eaa5ad 100644
--- a/odb/tracer/source.cxx
+++ b/odb/tracer/source.cxx
@@ -67,7 +67,7 @@ namespace tracer
            << "throw object_not_persistent ();"
            << "}";
 
-        // erase ()
+        // erase (id_type)
         //
         os << "void " << traits << "::" << endl
            << "erase (database&, const id_type& id)"
@@ -79,6 +79,18 @@ namespace tracer
            << "throw object_not_persistent ();"
            << "}";
 
+        // erase (object_type)
+        //
+        os << "void " << traits << "::" << endl
+           << "erase (database&, const object_type& obj)"
+           << "{"
+           << "std::cout << \"delete \" << type_name () << \" id \" << " <<
+          "obj." << id.name () << " << std::endl;"
+           << endl
+           << "if (obj." << id.name () << " == id_type ())" << endl
+           << "throw object_not_persistent ();"
+           << "}";
+
         // find ()
         //
         os << traits << "::pointer_type" << endl
diff --git a/odb/validator.cxx b/odb/validator.cxx
index 7dc7ea1..8a94357 100644
--- a/odb/validator.cxx
+++ b/odb/validator.cxx
@@ -107,12 +107,15 @@ namespace
     size_t count_;
   };
 
-  // Find id member.
+  // Find special members (id, version).
   //
-  struct id_member: traversal::class_
+  struct special_members: traversal::class_
   {
-    id_member (class_kind kind, bool& valid, semantics::data_member*& m)
-        : kind_ (kind), member_ (valid, m)
+    special_members (class_kind kind,
+                     bool& valid,
+                     semantics::data_member*& id,
+                     semantics::data_member*& optimistic)
+        : kind_ (kind), member_ (valid, id, optimistic)
     {
       if (kind != class_view)
         *this >> inherits_ >> *this;
@@ -161,8 +164,10 @@ namespace
   private:
     struct member: traversal::data_member
     {
-      member (bool& valid, semantics::data_member*& m)
-          : valid_ (valid), m_ (m)
+      member (bool& valid,
+              semantics::data_member*& id,
+              semantics::data_member*& optimistic)
+          : valid_ (valid), id_ (id), optimistic_ (optimistic)
       {
       }
 
@@ -171,23 +176,44 @@ namespace
       {
         if (m.count ("id"))
         {
-          if (m_ != 0)
+          if (id_ != 0)
           {
             cerr << m.file () << ":" << m.line () << ":" << m.column () << ":"
                  << " error: multiple object id members" << endl;
 
-            cerr << m_->file () << ":" << m_->line () << ":" << m_->column ()
-                 << ": info: previous id member declared here" << endl;
+            semantics::data_member& i (*id_);
+
+            cerr << i.file () << ":" << i.line () << ":" << i.column ()
+                 << ": info: previous id member is declared here" << endl;
+
+            valid_ = false;
+          }
+          else
+            id_ = &m;
+        }
+
+        if (m.count ("version"))
+        {
+          if (optimistic_ != 0)
+          {
+            cerr << m.file () << ":" << m.line () << ":" << m.column () << ":"
+                 << " error: multiple version members" << endl;
+
+            semantics::data_member& o (*optimistic_);
+
+            cerr << o.file () << ":" << o.line () << ":" << o.column ()
+                 << ": info: previous version member is declared here" << endl;
 
             valid_ = false;
           }
           else
-            m_ = &m;
+            optimistic_ = &m;
         }
       }
 
       bool& valid_;
-      semantics::data_member*& m_;
+      semantics::data_member*& id_;
+      semantics::data_member*& optimistic_;
     };
 
     class_kind kind_;
@@ -323,11 +349,12 @@ namespace
         }
       }
 
-      // Check id.
+      // Check special members.
       //
       semantics::data_member* id (0);
+      semantics::data_member* optimistic (0);
       {
-        id_member t (class_object, valid_, id);
+        special_members t (class_object, valid_, id, optimistic);
         t.traverse (c);
       }
 
@@ -339,10 +366,10 @@ namespace
         if (!(c.count ("id") || context::abstract (c)))
         {
           cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
-               << " error: no data member designated as object id" << endl;
+               << " error: no data member designated as an object id" << endl;
 
           cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
-               << " info: use '#pragma db id' to specify object id member"
+               << " info: use '#pragma db id' to specify an object id member"
                << endl;
 
           cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
@@ -382,6 +409,90 @@ namespace
           id->set ("not-null", true);
       }
 
+      if (optimistic != 0)
+      {
+        semantics::data_member& m (*optimistic);
+
+        // Make sure we have the class declared optimistic.
+        //
+        if (&optimistic->scope () == &c && !c.count ("optimistic"))
+        {
+          cerr << m.file () << ":" << m.line () << ":" << m.column () << ":"
+               << " error: version data member in a class not declared "
+               << "optimistic" << endl;
+
+          cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
+               << " info: use '#pragma db optimistic' to declare this "
+               << "class optimistic" << endl;
+
+          valid_ = false;
+        }
+
+        // Make sure we have object id.
+        //
+        if (id == 0)
+        {
+          cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
+               << " error: optimistic class without an object id" << endl;
+
+          valid_ = false;
+        }
+
+        // Make sure id and version members are in the same class. The
+        // current architecture relies on that.
+        //
+        if (id != 0 && &id->scope () != &optimistic->scope ())
+        {
+          cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
+               << " error: object id and version members are in different "
+               << "classes" << endl;
+
+          cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
+               << " info: object id and version members must be in the same "
+               << "class" << endl;
+
+          cerr << id->file () << ":" << id->line () << ":" << id->column ()
+               << ": info: object id member is declared here" << endl;
+
+          cerr << m.file () << ":" << m.line () << ":" << m.column () << ":"
+               << " error: version member is declared here" << endl;
+
+          valid_ = false;
+        }
+
+        // Make sure this class is not readonly.
+        //
+        if (c.count ("readonly"))
+        {
+          cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
+               << " error: optimistic class cannot be readonly" << endl;
+
+          valid_ = false;
+        }
+
+
+        // This takes care of also marking derived classes as optimistic.
+        //
+        c.set ("optimistic-member", optimistic);
+      }
+      else
+      {
+        // Make sure there is a version member if the class declared
+        // optimistic.
+        //
+        if (c.count ("optimistic"))
+        {
+          cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
+               << " error: optimistic class without a version member" << endl;
+
+          cerr << c.file () << ":" << c.line () << ":" << c.column () << ":"
+               << " info: use '#pragma db version' to declare on of the "
+               << "data members as a version" << endl;
+
+          valid_ = false;
+        }
+      }
+
       // Check members.
       //
       member_.count_ = 0;
@@ -451,20 +562,32 @@ namespace
       // Check id.
       //
       semantics::data_member* id (0);
+      semantics::data_member* optimistic (0);
       {
-        id_member t (class_view, valid_, id);
+        special_members t (class_view, valid_, id, optimistic);
         t.traverse (c);
       }
 
       if (id != 0)
       {
         cerr << id->file () << ":" << id->line () << ":" << id->column ()
-             << ": error: view type data member cannot be designated as "
+             << ": error: view type data member cannot be designated as an "
              << "object id" << endl;
 
         valid_ = false;
       }
 
+      if (optimistic != 0)
+      {
+        semantics::data_member& o (*optimistic);
+
+        cerr << o.file () << ":" << o.line () << ":" << o.column ()
+             << ": error: view type data member cannot be designated as a "
+             << "version" << endl;
+
+        valid_ = false;
+      }
+
       // Check members.
       //
       member_.count_ = 0;
@@ -517,20 +640,32 @@ namespace
       // Check id.
       //
       semantics::data_member* id (0);
+      semantics::data_member* optimistic (0);
       {
-        id_member t (class_composite, valid_, id);
+        special_members t (class_composite, valid_, id, optimistic);
         t.traverse (c);
       }
 
       if (id != 0)
       {
         cerr << id->file () << ":" << id->line () << ":" << id->column ()
-             << ": error: value type data member cannot be designated as "
+             << ": error: value type data member cannot be designated as an "
              << "object id" << endl;
 
         valid_ = false;
       }
 
+      if (optimistic != 0)
+      {
+        semantics::data_member& o (*optimistic);
+
+        cerr << o.file () << ":" << o.line () << ":" << o.column ()
+             << ": error: value type data member cannot be designated as a "
+             << "version" << endl;
+
+        valid_ = false;
+      }
+
       // Check members.
       //
       member_.count_ = 0;
@@ -574,7 +709,7 @@ namespace
 
         cerr << dm.file () << ":" << dm.line () << ":" << dm.column () << ":"
              << " error: inverse object pointer member '" << member_prefix_
-             << m.name () << "' in an object without id" << endl;
+             << m.name () << "' in an object without an object id" << endl;
 
         valid_ = false;
       }
@@ -587,7 +722,7 @@ namespace
 
       cerr << dm.file () << ":" << dm.line () << ":" << dm.column () << ":"
            << " error: container member '" << member_prefix_ << m.name ()
-           << "' in an object without id" << endl;
+           << "' in an object without an object id" << endl;
 
       valid_ = false;
     }