From nobody at rubyforge.org  Fri Sep 30 08:11:19 2011
From: nobody at rubyforge.org (nobody at rubyforge.org)
Date: Fri, 30 Sep 2011 08:11:19 -0400 (EDT)
Subject: [ruby-oci8-commit] [448] trunk/ruby-oci8: run connection-pool
 cleanup functions in a native thread not to block GC.
Message-ID: <20110930121119.D3EB41858379@rubyforge.org>

Revision: 448
Author:   kubo
Date:     2011-09-30 08:11:16 -0400 (Fri, 30 Sep 2011)

Log Message:
-----------
run connection-pool cleanup functions in a native thread not to block GC.
use xfree() instead of free() to release memory allocated by xmalloc().

Modified Paths:
--------------
    trunk/ruby-oci8/ChangeLog
    trunk/ruby-oci8/ext/oci8/connection_pool.c
    trunk/ruby-oci8/ext/oci8/oci8.c

Modified: trunk/ruby-oci8/ChangeLog
===================================================================
--- trunk/ruby-oci8/ChangeLog	2011-08-31 14:12:45 UTC (rev 447)
+++ trunk/ruby-oci8/ChangeLog	2011-09-30 12:11:16 UTC (rev 448)
@@ -1,3 +1,9 @@
+2011-09-30  KUBO Takehiro  <kubo at jiubao.org>
+	* ext/oci8/connection_pool.c: run connection-pool cleanup functions
+	    in a native thread not to block GC.
+	* ext/oci8/oci8.c: use xfree() instead of free() to release memory
+	    allocated by xmalloc().
+
 2011-08-31  KUBO Takehiro  <kubo at jiubao.org>
 	* ext/oci8/env.c, ext/oci8/extconf.rb, ext/oci8/oci8.c, ext/oci8/oci8.h,
 	  ext/oci8/oci8lib.c, ext/oci8/thread_util.c, ext/oci8/thread_util.h:

Modified: trunk/ruby-oci8/ext/oci8/connection_pool.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/connection_pool.c	2011-08-31 14:12:45 UTC (rev 447)
+++ trunk/ruby-oci8/ext/oci8/connection_pool.c	2011-09-30 12:11:16 UTC (rev 448)
@@ -21,9 +21,18 @@
     rb_gc_mark(cpool->pool_name);
 }
 
+static VALUE cpool_free_thread(void *arg)
+{
+    OCIConnectionPoolDestroy((OCICPool *)arg, oci8_errhp, OCI_DEFAULT);
+    OCIHandleFree(arg, OCI_HTYPE_CPOOL);
+    return 0;
+}
+
 static void oci8_cpool_free(oci8_base_t *base)
 {
-    OCIConnectionPoolDestroy(base->hp.poolhp, oci8_errhp, OCI_DEFAULT);
+    oci8_run_native_thread(cpool_free_thread, base->hp.poolhp);
+    base->type = 0;
+    base->hp.ptr = NULL;
 }
 
 static void oci8_cpool_init(oci8_base_t *base)

Modified: trunk/ruby-oci8/ext/oci8/oci8.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/oci8.c	2011-08-31 14:12:45 UTC (rev 447)
+++ trunk/ruby-oci8/ext/oci8/oci8.c	2011-09-30 12:11:16 UTC (rev 448)
@@ -267,7 +267,7 @@
 
     OCITransRollback(sla->svchp, errhp, OCI_DEFAULT);
     rv = OCILogoff(sla->svchp, errhp);
-    free(sla);
+    xfree(sla);
     return (VALUE)rv;
 }
 
@@ -325,7 +325,7 @@
     if (cla->svchp != NULL) {
         OCIHandleFree(cla->svchp, OCI_HTYPE_SVCCTX);
     }
-    free(cla);
+    xfree(cla);
     return (VALUE)rv;
 }
 



From nobody at rubyforge.org  Fri Sep 30 08:18:25 2011
From: nobody at rubyforge.org (nobody at rubyforge.org)
Date: Fri, 30 Sep 2011 08:18:25 -0400 (EDT)
Subject: [ruby-oci8-commit] [449] trunk/ruby-oci8: clear an executuing
 thread information in a connection when a SQL
Message-ID: <20110930121825.63F99185837A@rubyforge.org>

Revision: 449
Author:   kubo
Date:     2011-09-30 08:18:23 -0400 (Fri, 30 Sep 2011)

Log Message:
-----------
clear an executuing thread information in a connection when a SQL
executions is canceled by Thread#kill or Timeout::timeout.
(reported by Aaron Qian)
See: http://rubyforge.org/forum/forum.php?thread_id=50112&forum_id=1078

Modified Paths:
--------------
    trunk/ruby-oci8/ChangeLog
    trunk/ruby-oci8/ext/oci8/apiwrap.c.tmpl
    trunk/ruby-oci8/ext/oci8/oci8lib.c
    trunk/ruby-oci8/test/test_break.rb

Modified: trunk/ruby-oci8/ChangeLog
===================================================================
--- trunk/ruby-oci8/ChangeLog	2011-09-30 12:11:16 UTC (rev 448)
+++ trunk/ruby-oci8/ChangeLog	2011-09-30 12:18:23 UTC (rev 449)
@@ -1,4 +1,11 @@
 2011-09-30  KUBO Takehiro  <kubo at jiubao.org>
+	* ext/oci8/apiwrap.c.tmpl, ext/oci8/oci8lib.c, test/test_break.rb:
+	    clear an executuing thread information in a connection when a SQL
+	    executions is canceled by Thread#kill or Timeout::timeout.
+	    (reported by Aaron Qian)
+	    See: http://rubyforge.org/forum/forum.php?thread_id=50112&forum_id=1078
+
+2011-09-30  KUBO Takehiro  <kubo at jiubao.org>
 	* ext/oci8/connection_pool.c: run connection-pool cleanup functions
 	    in a native thread not to block GC.
 	* ext/oci8/oci8.c: use xfree() instead of free() to release memory

Modified: trunk/ruby-oci8/ext/oci8/apiwrap.c.tmpl
===================================================================
--- trunk/ruby-oci8/ext/oci8/apiwrap.c.tmpl	2011-09-30 12:11:16 UTC (rev 448)
+++ trunk/ruby-oci8/ext/oci8/apiwrap.c.tmpl	2011-09-30 12:18:23 UTC (rev 449)
@@ -4,6 +4,12 @@
 %>
 #define API_WRAP_C 1
 #include "apiwrap.h"
+#ifdef HAVE_RB_THREAD_BLOCKING_REGION
+#define BLOCKING_FUNCTION_EPILOGUE(svcctx) do { (svcctx)->executing_thread = Qnil; } while (0)
+#else
+#define BLOCKING_FUNCTION_EPILOGUE(svcctx) do { } while (0)
+#endif
+
 <%
 prev_name = ''
 funcs.each do |f|
@@ -33,6 +39,7 @@
  * <%=f.name%>_nb
  */
 typedef struct {
+    oci8_svcctx_t *svcctx;
 <%
    f.ret != 'void'
 %>    <%= f.ret %> rv;
@@ -56,9 +63,11 @@
 %>    data->rv = <%=f.name%>(<%= f.args.collect do |a| 'data->' + a.name; end.join(', ') %>);
 <% end %>
 <% if f.ret == 'sword'
-%>    return (VALUE)data->rv;
+%>    BLOCKING_FUNCTION_EPILOGUE(data->svcctx);
+    return (VALUE)data->rv;
 <% else
-%>    return (VALUE)0;
+%>    BLOCKING_FUNCTION_EPILOGUE(data->svcctx);
+    return (VALUE)0;
 <% end %>
 }
 #else
@@ -69,6 +78,7 @@
 {
     if (have_<%=f.name%>_nb) {
         oci8_<%=f.name%>_data_t data;
+        data.svcctx = svcctx;
 <% f.args.each do |a|
 %>        data.<%=a.name%> = <%=a.name%>;
 <% end

Modified: trunk/ruby-oci8/ext/oci8/oci8lib.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/oci8lib.c	2011-09-30 12:11:16 UTC (rev 448)
+++ trunk/ruby-oci8/ext/oci8/oci8lib.c	2011-09-30 12:18:23 UTC (rev 449)
@@ -246,8 +246,8 @@
             rb_raise(rb_eRuntimeError /* FIXME */, "executing in another thread");
         }
         svcctx->executing_thread = rb_thread_current();
+        /* Note: executing_thread is cleard at the end of the blocking function. */
         rv = (sword)rb_thread_blocking_region(func, data, oci8_unblock_func, svcctx);
-        svcctx->executing_thread = Qnil;
         if (rv == OCI_ERROR) {
             if (oci8_get_error_code(oci8_errhp) == 1013) {
                 rb_raise(eOCIBreak, "Canceled by user request.");
@@ -261,14 +261,20 @@
 #else /* HAVE_RB_THREAD_BLOCKING_REGION */
 
 /* ruby 1.8 */
-sword oci8_blocking_region(oci8_svcctx_t *svcctx, rb_blocking_function_t func, void *data)
+typedef struct {
+    oci8_svcctx_t *svcctx;
+    rb_blocking_function_t *func;
+    void *data;
+} blocking_region_arg_t;
+
+static VALUE blocking_function_execute(blocking_region_arg_t *arg)
 {
+    oci8_svcctx_t *svcctx = arg->svcctx;
+    rb_blocking_function_t *func = arg->func;
+    void *data = arg->data;
     struct timeval tv;
     sword rv;
 
-    if (!NIL_P(svcctx->executing_thread)) {
-        rb_raise(rb_eRuntimeError /* FIXME */, "executing in another thread");
-    }
     tv.tv_sec = 0;
     tv.tv_usec = 10000;
     svcctx->executing_thread = rb_thread_current();
@@ -279,8 +285,7 @@
     }
     if (rv == OCI_ERROR) {
         if (oci8_get_error_code(oci8_errhp) == 1013) {
-            if (have_OCIReset)
-                OCIReset(svcctx->base.hp.ptr, oci8_errhp);
+            OCIReset(svcctx->base.hp.ptr, oci8_errhp);
             svcctx->executing_thread = Qnil;
             rb_raise(eOCIBreak, "Canceled by user request.");
         }
@@ -288,6 +293,30 @@
     svcctx->executing_thread = Qnil;
     return rv;
 }
+
+static VALUE blocking_function_ensure(oci8_svcctx_t *svcctx)
+{
+    if (!NIL_P(svcctx->executing_thread)) {
+        /* The thread is killed. */
+        OCIBreak(svcctx->base.hp.ptr, oci8_errhp);
+        OCIReset(svcctx->base.hp.ptr, oci8_errhp);
+        svcctx->executing_thread = Qnil;
+    }
+    return Qnil;
+}
+
+sword oci8_blocking_region(oci8_svcctx_t *svcctx, rb_blocking_function_t func, void *data)
+{
+    blocking_region_arg_t arg;
+
+    arg.svcctx = svcctx;
+    arg.func = func;
+    arg.data = data;
+    if (!NIL_P(svcctx->executing_thread)) {
+        rb_raise(rb_eRuntimeError, "executing in another thread");
+    }
+    return (sword)rb_ensure(blocking_function_execute, (VALUE)&arg, blocking_function_ensure, (VALUE)svcctx);
+}
 #endif /* HAVE_RB_THREAD_BLOCKING_REGION */
 
 typedef struct {

Modified: trunk/ruby-oci8/test/test_break.rb
===================================================================
--- trunk/ruby-oci8/test/test_break.rb	2011-09-30 12:11:16 UTC (rev 448)
+++ trunk/ruby-oci8/test/test_break.rb	2011-09-30 12:18:23 UTC (rev 449)
@@ -1,6 +1,7 @@
 # High-level API
 require 'oci8'
 require 'test/unit'
+require 'timeout'
 require File.dirname(__FILE__) + '/config'
 
 class TestBreak < Test::Unit::TestCase
@@ -79,4 +80,16 @@
     expect[SEND_BREAK]   = TIME_TO_BREAK
     do_test_ocibreak(@conn, expect)
   end
+
+  def test_timeout
+    @conn.non_blocking = true
+    start_time = Time.now
+    assert_raise(Timeout::Error) do
+      Timeout.timeout(1) do
+        @conn.exec("BEGIN DBMS_LOCK.SLEEP(10); END;")
+      end
+    end
+    @conn.exec("BEGIN NULL; END;")
+    assert_operator(Time.now, :<, start_time + 2)
+  end
 end



From nobody at rubyforge.org  Fri Sep 30 23:14:45 2011
From: nobody at rubyforge.org (nobody at rubyforge.org)
Date: Fri, 30 Sep 2011 23:14:45 -0400 (EDT)
Subject: [ruby-oci8-commit] [450] trunk/ruby-oci8: rename oci8_*_class to
 oci8_*_vtable because they correspond to
Message-ID: <20111001031445.C9FC41D78101@rubyforge.org>

Revision: 450
Author:   kubo
Date:     2011-09-30 23:14:45 -0400 (Fri, 30 Sep 2011)

Log Message:
-----------
rename oci8_*_class to oci8_*_vtable because they correspond to
virtual method tables (vtable) in C++.

Modified Paths:
--------------
    trunk/ruby-oci8/ChangeLog
    trunk/ruby-oci8/ext/oci8/bind.c
    trunk/ruby-oci8/ext/oci8/connection_pool.c
    trunk/ruby-oci8/ext/oci8/lob.c
    trunk/ruby-oci8/ext/oci8/metadata.c
    trunk/ruby-oci8/ext/oci8/object.c
    trunk/ruby-oci8/ext/oci8/oci8.c
    trunk/ruby-oci8/ext/oci8/oci8.h
    trunk/ruby-oci8/ext/oci8/oci8lib.c
    trunk/ruby-oci8/ext/oci8/ocidatetime.c
    trunk/ruby-oci8/ext/oci8/ocihandle.c
    trunk/ruby-oci8/ext/oci8/ocinumber.c
    trunk/ruby-oci8/ext/oci8/oradate.c
    trunk/ruby-oci8/ext/oci8/stmt.c

Modified: trunk/ruby-oci8/ChangeLog
===================================================================
--- trunk/ruby-oci8/ChangeLog	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ChangeLog	2011-10-01 03:14:45 UTC (rev 450)
@@ -1,3 +1,11 @@
+2011-10-01  KUBO Takehiro  <kubo at jiubao.org>
+	* ext/oci8/bind.c, ext/oci8/connection_pool.c, ext/oci8/lob.c,
+	  ext/oci8/metadata.c, ext/oci8/object.c, ext/oci8/oci8.c, ext/oci8/oci8.h,
+	  ext/oci8/oci8lib.c, ext/oci8/ocidatetime.c, ext/oci8/ocihandle.c,
+	  ext/oci8/ocinumber.c, ext/oci8/oradate.c, ext/oci8/stmt.c:
+	    rename oci8_*_class to oci8_*_vtable because they correspond to
+	    virtual method tables (vtable) in C++.
+
 2011-09-30  KUBO Takehiro  <kubo at jiubao.org>
 	* ext/oci8/apiwrap.c.tmpl, ext/oci8/oci8lib.c, test/test_break.rb:
 	    clear an executuing thread information in a connection when a SQL

Modified: trunk/ruby-oci8/ext/oci8/bind.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/bind.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/bind.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -102,7 +102,7 @@
     oci_lc(OCIAttrSet(obind->base.hp.ptr, obind->base.type, (void*)&obs->csfrm, 0, OCI_ATTR_CHARSET_FORM, oci8_errhp));
 }
 
-static const oci8_bind_class_t bind_string_class = {
+static const oci8_bind_vtable_t bind_string_vtable = {
     {
         NULL,
         oci8_bind_free,
@@ -139,7 +139,7 @@
     vstr->size = RSTRING_LEN(val);
 }
 
-static const oci8_bind_class_t bind_raw_class = {
+static const oci8_bind_vtable_t bind_raw_vtable = {
     {
         NULL,
         oci8_bind_free,
@@ -176,7 +176,7 @@
 #ifndef SQLT_BDOUBLE
 #define SQLT_BDOUBLE 22
 #endif
-static const oci8_bind_class_t bind_binary_double_class = {
+static const oci8_bind_vtable_t bind_binary_double_vtable = {
     {
         NULL,
         oci8_bind_free,
@@ -193,7 +193,7 @@
 static VALUE oci8_bind_get(VALUE self)
 {
     oci8_bind_t *obind = DATA_PTR(self);
-    const oci8_bind_class_t *obc = (const oci8_bind_class_t *)obind->base.klass;
+    const oci8_bind_vtable_t *vptr = (const oci8_bind_vtable_t *)obind->base.vptr;
     ub4 idx = obind->curar_idx;
     void **null_structp = NULL;
 
@@ -201,7 +201,7 @@
         if (obind->u.inds[idx] != 0)
             return Qnil;
     }
-    return obc->get(obind, (void*)((size_t)obind->valuep + obind->alloc_sz * idx), null_structp);
+    return vptr->get(obind, (void*)((size_t)obind->valuep + obind->alloc_sz * idx), null_structp);
 }
 
 VALUE oci8_bind_get_data(VALUE self)
@@ -226,7 +226,7 @@
 static VALUE oci8_bind_set(VALUE self, VALUE val)
 {
     oci8_bind_t *obind = DATA_PTR(self);
-    const oci8_bind_class_t *obc = (const oci8_bind_class_t *)obind->base.klass;
+    const oci8_bind_vtable_t *vptr = (const oci8_bind_vtable_t *)obind->base.vptr;
     ub4 idx = obind->curar_idx;
 
     if (NIL_P(val)) {
@@ -245,7 +245,7 @@
             null_structp = &obind->u.null_structs[idx];
             *(OCIInd*)obind->u.null_structs[idx] = 0;
         }
-        obc->set(obind, (void*)((size_t)obind->valuep + obind->alloc_sz * idx), null_structp, val);
+        vptr->set(obind, (void*)((size_t)obind->valuep + obind->alloc_sz * idx), null_structp, val);
     }
     return self;
 }
@@ -277,7 +277,7 @@
 static VALUE oci8_bind_initialize(VALUE self, VALUE svc, VALUE val, VALUE length, VALUE max_array_size)
 {
     oci8_bind_t *obind = DATA_PTR(self);
-    const oci8_bind_class_t *bind_class = (const oci8_bind_class_t *)obind->base.klass;
+    const oci8_bind_vtable_t *bind_class = (const oci8_bind_vtable_t *)obind->base.vptr;
     ub4 cnt = 1;
 
     obind->tdo = Qnil;
@@ -349,10 +349,10 @@
     rb_define_method(cOCI8BindTypeBase, "set", oci8_bind_set, 1);
 
     /* register primitive data types. */
-    oci8_define_bind_class("String", &bind_string_class);
-    oci8_define_bind_class("RAW", &bind_raw_class);
+    oci8_define_bind_class("String", &bind_string_vtable);
+    oci8_define_bind_class("RAW", &bind_raw_vtable);
     if (oracle_client_version >= ORAVER_10_1) {
-        oci8_define_bind_class("BinaryDouble", &bind_binary_double_class);
+        oci8_define_bind_class("BinaryDouble", &bind_binary_double_vtable);
     }
 }
 

Modified: trunk/ruby-oci8/ext/oci8/connection_pool.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/connection_pool.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/connection_pool.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -42,7 +42,7 @@
     cpool->pool_name = Qnil;
 }
 
-static oci8_base_class_t oci8_cpool_class = {
+static oci8_base_vtable_t oci8_cpool_vtable = {
     oci8_cpool_mark,
     oci8_cpool_free,
     sizeof(oci8_base_t),
@@ -189,7 +189,7 @@
     cOCIConnectionPool = rb_define_class_under(cOCI8, "ConnectionPool", cOCIHandle);
 #endif
 
-    cOCIConnectionPool = oci8_define_class_under(cOCI8, "ConnectionPool", &oci8_cpool_class);
+    cOCIConnectionPool = oci8_define_class_under(cOCI8, "ConnectionPool", &oci8_cpool_vtable);
 
     rb_define_private_method(cOCIConnectionPool, "initialize", oci8_cpool_initialize, -1);
     rb_define_method(cOCIConnectionPool, "reinitialize", oci8_cpool_reinitialize, 3);

Modified: trunk/ruby-oci8/ext/oci8/lob.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/lob.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/lob.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -113,7 +113,7 @@
     lob->svchp = NULL;
 }
 
-static oci8_base_class_t oci8_lob_class = {
+static oci8_base_vtable_t oci8_lob_vtable = {
     oci8_lob_mark,
     oci8_lob_free,
     sizeof(oci8_lob_t),
@@ -631,9 +631,9 @@
  */
 
 typedef struct {
-    oci8_bind_class_t bind;
+    oci8_bind_vtable_t bind;
     VALUE *klass;
-} oci8_bind_lob_class_t;
+} oci8_bind_lob_vtable_t;
 
 static VALUE bind_lob_get(oci8_bind_t *obind, void *data, void *null_struct)
 {
@@ -644,10 +644,10 @@
 static void bind_lob_set(oci8_bind_t *obind, void *data, void **null_structp, VALUE val)
 {
     oci8_hp_obj_t *oho = (oci8_hp_obj_t *)data;
-    const oci8_bind_lob_class_t *klass = (const oci8_bind_lob_class_t *)obind->base.klass;
+    const oci8_bind_lob_vtable_t *vptr = (const oci8_bind_lob_vtable_t *)obind->base.vptr;
     oci8_base_t *h;
-    if (!rb_obj_is_kind_of(val, *klass->klass))
-        rb_raise(rb_eArgError, "Invalid argument: %s (expect %s)", rb_class2name(CLASS_OF(val)), rb_class2name(*klass->klass));
+    if (!rb_obj_is_kind_of(val, *vptr->klass))
+        rb_raise(rb_eArgError, "Invalid argument: %s (expect %s)", rb_class2name(CLASS_OF(val)), rb_class2name(*vptr->klass));
     h = DATA_PTR(val);
     oho->hp = h->hp.ptr;
     oho->obj = val;
@@ -661,13 +661,13 @@
 
 static void bind_lob_init_elem(oci8_bind_t *obind, VALUE svc)
 {
-    const oci8_bind_lob_class_t *klass = (const oci8_bind_lob_class_t *)obind->base.klass;
+    const oci8_bind_lob_vtable_t *vptr = (const oci8_bind_lob_vtable_t *)obind->base.vptr;
     oci8_hp_obj_t *oho = (oci8_hp_obj_t *)obind->valuep;
     oci8_base_t *h;
     ub4 idx = 0;
 
     do {
-        oho[idx].obj = rb_funcall(*klass->klass, oci8_id_new, 1, svc);
+        oho[idx].obj = rb_funcall(*vptr->klass, oci8_id_new, 1, svc);
         h = DATA_PTR(oho[idx].obj);
         oho[idx].hp = h->hp.ptr;
     } while (++idx < obind->maxar_sz);
@@ -680,7 +680,7 @@
     oci_lc(OCIAttrSet(obind->base.hp.ptr, obind->base.type, (void*)&csfrm, 0, OCI_ATTR_CHARSET_FORM, oci8_errhp));
 }
 
-static const oci8_bind_lob_class_t bind_clob_class = {
+static const oci8_bind_lob_vtable_t bind_clob_vtable = {
     {
         {
             oci8_bind_hp_obj_mark,
@@ -697,7 +697,7 @@
     &cOCI8CLOB
 };
 
-static const oci8_bind_lob_class_t bind_nclob_class = {
+static const oci8_bind_lob_vtable_t bind_nclob_vtable = {
     {
         {
             oci8_bind_hp_obj_mark,
@@ -715,7 +715,7 @@
     &cOCI8NCLOB
 };
 
-static const oci8_bind_lob_class_t bind_blob_class = {
+static const oci8_bind_lob_vtable_t bind_blob_vtable = {
     {
         {
             oci8_bind_hp_obj_mark,
@@ -732,7 +732,7 @@
     &cOCI8BLOB
 };
 
-static const oci8_bind_lob_class_t bind_bfile_class = {
+static const oci8_bind_lob_vtable_t bind_bfile_vtable = {
     {
         {
             oci8_bind_hp_obj_mark,
@@ -758,7 +758,7 @@
     seek_cur = rb_eval_string("::IO::SEEK_CUR");
     seek_end = rb_eval_string("::IO::SEEK_END");
 
-    cOCI8LOB = oci8_define_class_under(cOCI8, "LOB", &oci8_lob_class);
+    cOCI8LOB = oci8_define_class_under(cOCI8, "LOB", &oci8_lob_vtable);
     cOCI8CLOB = rb_define_class_under(cOCI8, "CLOB", cOCI8LOB);
     cOCI8NCLOB = rb_define_class_under(cOCI8, "NCLOB", cOCI8LOB);
     cOCI8BLOB = rb_define_class_under(cOCI8, "BLOB", cOCI8LOB);
@@ -795,8 +795,8 @@
     rb_define_method(cOCI8BFILE, "size=", oci8_bfile_error, 1);
     rb_define_method(cOCI8BFILE, "write", oci8_bfile_error, 1);
 
-    oci8_define_bind_class("CLOB", &bind_clob_class.bind);
-    oci8_define_bind_class("NCLOB", &bind_nclob_class.bind);
-    oci8_define_bind_class("BLOB", &bind_blob_class.bind);
-    oci8_define_bind_class("BFILE", &bind_bfile_class.bind);
+    oci8_define_bind_class("CLOB", &bind_clob_vtable.bind);
+    oci8_define_bind_class("NCLOB", &bind_nclob_vtable.bind);
+    oci8_define_bind_class("BLOB", &bind_blob_vtable.bind);
+    oci8_define_bind_class("BFILE", &bind_bfile_vtable.bind);
 }

Modified: trunk/ruby-oci8/ext/oci8/metadata.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/metadata.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/metadata.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -191,7 +191,7 @@
 #endif
 }
 
-oci8_base_class_t oci8_metadata_class = {
+oci8_base_vtable_t oci8_metadata_vtable = {
     oci8_metadata_mark,
     NULL,
     sizeof(oci8_metadata_t),
@@ -200,7 +200,7 @@
 void Init_oci8_metadata(VALUE cOCI8)
 {
     mOCI8Metadata = rb_define_module_under(cOCI8, "Metadata");
-    cOCI8MetadataBase = oci8_define_class_under(mOCI8Metadata, "Base", &oci8_metadata_class);
+    cOCI8MetadataBase = oci8_define_class_under(mOCI8Metadata, "Base", &oci8_metadata_vtable);
     ptype_to_class = rb_hash_new();
     class_to_ptype = rb_hash_new();
     rb_global_variable(&ptype_to_class);

Modified: trunk/ruby-oci8/ext/oci8/object.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/object.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/object.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -88,7 +88,7 @@
     return self;
 }
 
-static oci8_base_class_t oci8_tdo_class = {
+static oci8_base_vtable_t oci8_tdo_vtable = {
     oci8_tdo_mark,
     oci8_tdo_free,
     sizeof(oci8_base_t)
@@ -536,7 +536,7 @@
     *ind = 0;
 }
 
-static oci8_base_class_t oci8_named_type_class = {
+static oci8_base_vtable_t oci8_named_type_vtable = {
     oci8_named_type_mark,
     oci8_named_type_free,
     sizeof(oci8_named_type_t)
@@ -645,7 +645,7 @@
     }
 }
 
-static const oci8_bind_class_t bind_named_type_class = {
+static const oci8_bind_vtable_t bind_named_type_vtable = {
     {
         bind_named_type_mark,
         bind_named_type_free,
@@ -666,7 +666,7 @@
     id_set_attributes = rb_intern("attributes=");
 
     /* OCI8::TDO */
-    cOCI8TDO = oci8_define_class_under(cOCI8, "TDO", &oci8_tdo_class);
+    cOCI8TDO = oci8_define_class_under(cOCI8, "TDO", &oci8_tdo_vtable);
     rb_define_private_method(cOCI8TDO, "setup", oci8_tdo_setup, 2);
     rb_define_const(cOCI8TDO, "ATTR_STRING", INT2FIX(ATTR_STRING));
     rb_define_const(cOCI8TDO, "ATTR_RAW", INT2FIX(ATTR_RAW));
@@ -695,7 +695,7 @@
     rb_define_const(cOCI8TDO, "ALIGNMENT_OF_DOUBLE", INT2FIX(ALIGNMENT_OF(double)));
 
     /* OCI8::NamedType */
-    cOCI8NamedType = oci8_define_class_under(cOCI8, "NamedType", &oci8_named_type_class);
+    cOCI8NamedType = oci8_define_class_under(cOCI8, "NamedType", &oci8_named_type_vtable);
     rb_define_method(cOCI8NamedType, "initialize", oci8_named_type_initialize, 0);
     rb_define_method(cOCI8NamedType, "tdo", oci8_named_type_tdo, 0);
     rb_define_private_method(cOCI8NamedType, "get_attribute", oci8_named_type_get_attribute, 4);
@@ -704,12 +704,12 @@
     rb_define_method(cOCI8NamedType, "null=", oci8_named_type_set_null, 1);
 
     /* OCI8::NamedCollection */
-    cOCI8NamedCollection = oci8_define_class_under(cOCI8, "NamedCollection", &oci8_named_type_class);
+    cOCI8NamedCollection = oci8_define_class_under(cOCI8, "NamedCollection", &oci8_named_type_vtable);
     rb_define_method(cOCI8NamedCollection, "initialize", oci8_named_type_initialize, 0);
     rb_define_method(cOCI8NamedCollection, "tdo", oci8_named_type_tdo, 0);
     rb_define_private_method(cOCI8NamedCollection, "get_coll_element", oci8_named_coll_get_coll_element, 2);
     rb_define_private_method(cOCI8NamedCollection, "set_coll_element", oci8_named_coll_set_coll_element, 3);
 
     /* OCI8::BindType::NamedType */
-    cOCI8BindNamedType = oci8_define_bind_class("NamedType", &bind_named_type_class);
+    cOCI8BindNamedType = oci8_define_bind_class("NamedType", &bind_named_type_vtable);
 }

Modified: trunk/ruby-oci8/ext/oci8/oci8.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/oci8.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/oci8.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -51,7 +51,7 @@
     base->hp.ptr = NULL;
 }
 
-static oci8_base_class_t oci8_svcctx_associate_class = {
+static oci8_base_vtable_t oci8_svcctx_associate_vtable = {
     NULL,
     oci8_svcctx_associate_free,
     sizeof(oci8_svcctx_associate_t),
@@ -121,7 +121,7 @@
     svcctx->long_read_len = INT2FIX(65535);
 }
 
-static oci8_base_class_t oci8_svcctx_class = {
+static oci8_base_vtable_t oci8_svcctx_vtable = {
     NULL,
     oci8_svcctx_free,
     sizeof(oci8_svcctx_t),
@@ -1106,9 +1106,9 @@
     oci8_cOCIHandle = rb_define_class("OCIHandle", rb_cObject);
     cOCI8 = rb_define_class("OCI8", oci8_cOCIHandle);
 #endif
-    cOCI8 = oci8_define_class("OCI8", &oci8_svcctx_class);
-    cSession = oci8_define_class_under(cOCI8, "Session", &oci8_svcctx_associate_class);
-    cServer = oci8_define_class_under(cOCI8, "Server", &oci8_svcctx_associate_class);
+    cOCI8 = oci8_define_class("OCI8", &oci8_svcctx_vtable);
+    cSession = oci8_define_class_under(cOCI8, "Session", &oci8_svcctx_associate_vtable);
+    cServer = oci8_define_class_under(cOCI8, "Server", &oci8_svcctx_associate_vtable);
     id_at_session_handle = rb_intern("@session_handle");
     id_at_server_handle = rb_intern("@server_handle");
 

Modified: trunk/ruby-oci8/ext/oci8/oci8.h
===================================================================
--- trunk/ruby-oci8/ext/oci8/oci8.h	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/oci8.h	2011-10-01 03:14:45 UTC (rev 450)
@@ -237,21 +237,23 @@
     char buf[1];
 } oci8_vstr_t;
 
-typedef struct oci8_base_class oci8_base_class_t;
-typedef struct oci8_bind_class oci8_bind_class_t;
+typedef struct oci8_base_vtable oci8_base_vtable_t;
+typedef struct oci8_bind_vtable oci8_bind_vtable_t;
 
 typedef struct oci8_base oci8_base_t;
 typedef struct oci8_bind oci8_bind_t;
 
-struct oci8_base_class {
+/* The virtual method table of oci8_base_t */
+struct oci8_base_vtable {
     void (*mark)(oci8_base_t *base);
     void (*free)(oci8_base_t *base);
     size_t size;
     void (*init)(oci8_base_t *base);
 };
 
-struct oci8_bind_class {
-    oci8_base_class_t base;
+/* The virtual method table of oci8_bind_t */
+struct oci8_bind_vtable {
+    oci8_base_vtable_t base;
     VALUE (*get)(oci8_bind_t *obind, void *data, void *null_struct);
     void (*set)(oci8_bind_t *obind, void *data, void **null_structp, VALUE val);
     void (*init)(oci8_bind_t *obind, VALUE svc, VALUE val, VALUE length);
@@ -261,7 +263,14 @@
     void (*post_bind_hook)(oci8_bind_t *obind);
 };
 
+/* Class structure implemented by C language.
+ * oci8_base_t represents OCIHandle and its subclasses.
+ *
+ * The vptr member points to a virtual method table.
+ * See: http://en.wikipedia.org/wiki/Virtual_method_table
+ */
 struct oci8_base {
+    const oci8_base_vtable_t *vptr;
     ub4 type;
     union {
         dvoid *ptr;
@@ -278,13 +287,18 @@
         OCIDescribe *dschp;
     } hp;
     VALUE self;
-    const oci8_base_class_t *klass;
     oci8_base_t *parent;
     oci8_base_t *next;
     oci8_base_t *prev;
     oci8_base_t *children;
 };
 
+/* Class structure implemented by C language.
+ * This represents OCI8::BindType::Base's subclasses.
+ *
+ * This is a subclass of oci8_base_t because the first member
+ * base is oci8_base_t itself.
+ */
 struct oci8_bind {
     oci8_base_t base;
     void *valuep;
@@ -401,7 +415,7 @@
 extern ID oci8_id_get;
 extern ID oci8_id_set;
 extern ID oci8_id_keys;
-extern ID oci8_id_oci8_class;
+extern ID oci8_id_oci8_vtable;
 #ifdef CHAR_IS_NOT_A_SHORTCUT_TO_ID
 extern ID oci8_id_add_op; /* ID of the addition operator '+' */
 extern ID oci8_id_sub_op; /* ID of the subtraction operator '-' */
@@ -416,9 +430,9 @@
 extern int oci8_in_finalizer;
 extern VALUE oci8_cOCIHandle;
 void oci8_base_free(oci8_base_t *base);
-VALUE oci8_define_class(const char *name, oci8_base_class_t *klass);
-VALUE oci8_define_class_under(VALUE outer, const char *name, oci8_base_class_t *klass);
-VALUE oci8_define_bind_class(const char *name, const oci8_bind_class_t *oci8_bind_class);
+VALUE oci8_define_class(const char *name, oci8_base_vtable_t *vptr);
+VALUE oci8_define_class_under(VALUE outer, const char *name, oci8_base_vtable_t *vptr);
+VALUE oci8_define_bind_class(const char *name, const oci8_bind_vtable_t *vptr);
 void oci8_link_to_parent(oci8_base_t *base, oci8_base_t *parent);
 void oci8_unlink_from_parent(oci8_base_t *base);
 sword oci8_blocking_region(oci8_svcctx_t *svcctx, rb_blocking_function_t func, void *data);

Modified: trunk/ruby-oci8/ext/oci8/oci8lib.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/oci8lib.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/oci8lib.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -14,7 +14,7 @@
 ID oci8_id_get;
 ID oci8_id_set;
 ID oci8_id_keys;
-ID oci8_id_oci8_class;
+ID oci8_id_oci8_vtable;
 #ifdef CHAR_IS_NOT_A_SHORTCUT_TO_ID
 ID oci8_id_add_op;
 ID oci8_id_sub_op;
@@ -34,8 +34,8 @@
         oci8_base_free(base->children);
     }
     oci8_unlink_from_parent(base);
-    if (base->klass->free != NULL)
-        base->klass->free(base);
+    if (base->vptr->free != NULL)
+        base->vptr->free(base);
     if (base->type >= OCI_DTYPE_FIRST)
         OCIDescriptorFree(base->hp.ptr, base->type);
     else if (base->type >= OCI_HTYPE_FIRST)
@@ -79,7 +79,7 @@
     oci8_id_get = rb_intern("get");
     oci8_id_set = rb_intern("set");
     oci8_id_keys = rb_intern("keys");
-    oci8_id_oci8_class = rb_intern("__oci8_class__");
+    oci8_id_oci8_vtable = rb_intern("__oci8_vtable__");
 #ifdef CHAR_IS_NOT_A_SHORTCUT_TO_ID
     oci8_id_add_op = rb_intern("+");
     oci8_id_sub_op = rb_intern("-");
@@ -144,27 +144,27 @@
 #endif
 }
 
-VALUE oci8_define_class(const char *name, oci8_base_class_t *base_class)
+VALUE oci8_define_class(const char *name, oci8_base_vtable_t *vptr)
 {
     VALUE klass = rb_define_class(name, oci8_cOCIHandle);
-    VALUE obj = Data_Wrap_Struct(rb_cObject, 0, 0, base_class);
-    rb_ivar_set(klass, oci8_id_oci8_class, obj);
+    VALUE obj = Data_Wrap_Struct(rb_cObject, 0, 0, vptr);
+    rb_ivar_set(klass, oci8_id_oci8_vtable, obj);
     return klass;
 }
 
-VALUE oci8_define_class_under(VALUE outer, const char *name, oci8_base_class_t *base_class)
+VALUE oci8_define_class_under(VALUE outer, const char *name, oci8_base_vtable_t *vptr)
 {
     VALUE klass = rb_define_class_under(outer, name, oci8_cOCIHandle);
-    VALUE obj = Data_Wrap_Struct(rb_cObject, 0, 0, base_class);
-    rb_ivar_set(klass, oci8_id_oci8_class, obj);
+    VALUE obj = Data_Wrap_Struct(rb_cObject, 0, 0, vptr);
+    rb_ivar_set(klass, oci8_id_oci8_vtable, obj);
     return klass;
 }
 
-VALUE oci8_define_bind_class(const char *name, const oci8_bind_class_t *bind_class)
+VALUE oci8_define_bind_class(const char *name, const oci8_bind_vtable_t *vptr)
 {
     VALUE klass = rb_define_class_under(mOCI8BindType, name, cOCI8BindTypeBase);
-    VALUE obj = Data_Wrap_Struct(rb_cObject, 0, 0, (void*)bind_class);
-    rb_ivar_set(klass, oci8_id_oci8_class, obj);
+    VALUE obj = Data_Wrap_Struct(rb_cObject, 0, 0, (void*)vptr);
+    rb_ivar_set(klass, oci8_id_oci8_vtable, obj);
     return klass;
 }
 

Modified: trunk/ruby-oci8/ext/oci8/ocidatetime.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/ocidatetime.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/ocidatetime.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -252,7 +252,7 @@
     bind_free_common(base, OCI_DTYPE_TIMESTAMP_TZ);
 }
 
-static const oci8_bind_class_t bind_ocitimestamp_tz_class = {
+static const oci8_bind_vtable_t bind_ocitimestamp_tz_vtable = {
     {
         NULL,
         bind_ocitimestamp_tz_free,
@@ -423,7 +423,7 @@
     bind_free_common(base, OCI_DTYPE_INTERVAL_DS);
 }
 
-static const oci8_bind_class_t bind_ociinterval_ym_class = {
+static const oci8_bind_vtable_t bind_ociinterval_ym_vtable = {
     {
         NULL,
         bind_ociinterval_ym_free,
@@ -437,7 +437,7 @@
     SQLT_INTERVAL_YM
 };
 
-static const oci8_bind_class_t bind_ociinterval_ds_class = {
+static const oci8_bind_vtable_t bind_ociinterval_ds_vtable = {
     {
         NULL,
         bind_ociinterval_ds_free,
@@ -453,7 +453,7 @@
 
 void Init_oci_datetime(void)
 {
-    oci8_define_bind_class("OCITimestampTZ", &bind_ocitimestamp_tz_class);
-    oci8_define_bind_class("OCIIntervalYM", &bind_ociinterval_ym_class);
-    oci8_define_bind_class("OCIIntervalDS", &bind_ociinterval_ds_class);
+    oci8_define_bind_class("OCITimestampTZ", &bind_ocitimestamp_tz_vtable);
+    oci8_define_bind_class("OCIIntervalYM", &bind_ociinterval_ym_vtable);
+    oci8_define_bind_class("OCIIntervalDS", &bind_ociinterval_ds_vtable);
 }

Modified: trunk/ruby-oci8/ext/oci8/ocihandle.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/ocihandle.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/ocihandle.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -26,7 +26,7 @@
 }
 
 
-static oci8_base_class_t oci8_base_class = {
+static oci8_base_vtable_t oci8_base_vtable = {
     NULL,
     NULL,
     sizeof(oci8_base_t),
@@ -55,8 +55,8 @@
 
 static void oci8_handle_mark(oci8_base_t *base)
 {
-    if (base->klass->mark != NULL)
-        base->klass->mark(base);
+    if (base->vptr->mark != NULL)
+        base->vptr->mark(base);
 }
 
 static void oci8_handle_cleanup(oci8_base_t *base)
@@ -76,31 +76,31 @@
 static VALUE oci8_s_allocate(VALUE klass)
 {
     oci8_base_t *base;
-    const oci8_base_class_t *base_class;
+    const oci8_base_vtable_t *vptr;
     VALUE superklass;
     VALUE obj;
 
     superklass = klass;
-    while (!RTEST(rb_ivar_defined(superklass, oci8_id_oci8_class))) {
+    while (!RTEST(rb_ivar_defined(superklass, oci8_id_oci8_vtable))) {
         superklass = rb_class_superclass(superklass);
         if (superklass == rb_cObject)
             rb_raise(rb_eRuntimeError, "private method `new' called for %s:Class", rb_class2name(klass));
     }
-    obj = rb_ivar_get(superklass, oci8_id_oci8_class);
-    base_class = DATA_PTR(obj);
+    obj = rb_ivar_get(superklass, oci8_id_oci8_vtable);
+    vptr = DATA_PTR(obj);
 
-    base = xmalloc(base_class->size);
-    memset(base, 0, base_class->size);
+    base = xmalloc(vptr->size);
+    memset(base, 0, vptr->size);
 
     obj = Data_Wrap_Struct(klass, oci8_handle_mark, oci8_handle_cleanup, base);
     base->self = obj;
-    base->klass = base_class;
+    base->vptr = vptr;
     base->parent = NULL;
     base->next = base;
     base->prev = base;
     base->children = NULL;
-    if (base_class->init != NULL) {
-        base_class->init(base);
+    if (vptr->init != NULL) {
+        vptr->init(base);
     }
     return obj;
 }
@@ -717,8 +717,8 @@
     rb_define_alloc_func(oci8_cOCIHandle, oci8_s_allocate);
     rb_define_method_nodoc(oci8_cOCIHandle, "initialize", oci8_handle_initialize, 0);
     rb_define_private_method(oci8_cOCIHandle, "free", oci8_handle_free, 0);
-    obj = Data_Wrap_Struct(rb_cObject, 0, 0, &oci8_base_class);
-    rb_ivar_set(oci8_cOCIHandle, oci8_id_oci8_class, obj);
+    obj = Data_Wrap_Struct(rb_cObject, 0, 0, &oci8_base_vtable);
+    rb_ivar_set(oci8_cOCIHandle, oci8_id_oci8_vtable, obj);
 
     /* methods to get attributes */
     rb_define_private_method(oci8_cOCIHandle, "attr_get_ub1", attr_get_ub1, 1);

Modified: trunk/ruby-oci8/ext/oci8/ocinumber.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/ocinumber.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/ocinumber.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -1454,7 +1454,7 @@
     } while (++idx < obind->maxar_sz);
 }
 
-static const oci8_bind_class_t bind_ocinumber_class = {
+static const oci8_bind_vtable_t bind_ocinumber_vtable = {
     {
         NULL,
         oci8_bind_free,
@@ -1468,7 +1468,7 @@
     SQLT_VNU,
 };
 
-static const oci8_bind_class_t bind_integer_class = {
+static const oci8_bind_vtable_t bind_integer_vtable = {
     {
         NULL,
         oci8_bind_free,
@@ -1482,7 +1482,7 @@
     SQLT_VNU,
 };
 
-static const oci8_bind_class_t bind_float_class = {
+static const oci8_bind_vtable_t bind_float_vtable = {
     {
         NULL,
         oci8_bind_free,
@@ -1613,9 +1613,9 @@
     rb_define_method(cOCINumber, "_dump", onum__dump, -1);
     rb_define_singleton_method(cOCINumber, "_load", onum_s_load, 1);
 
-    oci8_define_bind_class("OraNumber", &bind_ocinumber_class);
-    oci8_define_bind_class("Integer", &bind_integer_class);
-    oci8_define_bind_class("Float", &bind_float_class);
+    oci8_define_bind_class("OraNumber", &bind_ocinumber_vtable);
+    oci8_define_bind_class("Integer", &bind_integer_vtable);
+    oci8_define_bind_class("Float", &bind_float_vtable);
 }
 
 OCINumber *oci8_get_ocinumber(VALUE num)

Modified: trunk/ruby-oci8/ext/oci8/oradate.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/oradate.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/oradate.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -557,7 +557,7 @@
     } while (++idx < obind->maxar_sz);
 }
 
-static const oci8_bind_class_t bind_oradate_class = {
+static const oci8_bind_vtable_t bind_oradate_vtable = {
     {
         NULL,
         oci8_bind_free,
@@ -610,5 +610,5 @@
     rb_define_method(cOraDate, "_dump", ora_date_dump, -1);
     rb_define_singleton_method(cOraDate, "_load", ora_date_s_load, 1);
 
-    oci8_define_bind_class("OraDate", &bind_oradate_class);
+    oci8_define_bind_class("OraDate", &bind_oradate_vtable);
 }

Modified: trunk/ruby-oci8/ext/oci8/stmt.c
===================================================================
--- trunk/ruby-oci8/ext/oci8/stmt.c	2011-09-30 12:18:23 UTC (rev 449)
+++ trunk/ruby-oci8/ext/oci8/stmt.c	2011-10-01 03:14:45 UTC (rev 450)
@@ -53,7 +53,7 @@
     stmt->defns = Qnil;
 }
 
-static oci8_base_class_t oci8_stmt_class = {
+static oci8_base_vtable_t oci8_stmt_vtable = {
     oci8_stmt_mark,
     oci8_stmt_free,
     sizeof(oci8_stmt_t),
@@ -99,7 +99,7 @@
     oci8_stmt_t *stmt = TO_STMT(self);
     ub4 position;
     oci8_bind_t *obind;
-    const oci8_bind_class_t *bind_class;
+    const oci8_bind_vtable_t *vptr;
     sword status;
 
     position = NUM2INT(vposition); /* 1 */
@@ -107,8 +107,8 @@
     if (obind->base.hp.dfn != NULL) {
         oci8_base_free(&obind->base); /* TODO: OK? */
     }
-    bind_class = (const oci8_bind_class_t *)obind->base.klass;
-    status = OCIDefineByPos(stmt->base.hp.stmt, &obind->base.hp.dfn, oci8_errhp, position, obind->valuep, obind->value_sz, bind_class->dty, NIL_P(obind->tdo) ? obind->u.inds : NULL, NULL, 0, OCI_DEFAULT);
+    vptr = (const oci8_bind_vtable_t *)obind->base.vptr;
+    status = OCIDefineByPos(stmt->base.hp.stmt, &obind->base.hp.dfn, oci8_errhp, position, obind->valuep, obind->value_sz, vptr->dty, NIL_P(obind->tdo) ? obind->u.inds : NULL, NULL, 0, OCI_DEFAULT);
     if (status != OCI_SUCCESS) {
         oci8_raise(oci8_errhp, status, stmt->base.hp.ptr);
     }
@@ -120,8 +120,8 @@
     if (NIL_P(obind->tdo) && obind->maxar_sz > 0) {
         oci_lc(OCIDefineArrayOfStruct(obind->base.hp.dfn, oci8_errhp, obind->alloc_sz, sizeof(sb2), 0, 0));
     }
-    if (bind_class->post_bind_hook != NULL) {
-        bind_class->post_bind_hook(obind);
+    if (vptr->post_bind_hook != NULL) {
+        vptr->post_bind_hook(obind);
     }
     if (position - 1 < RARRAY_LEN(stmt->defns)) {
         VALUE old_value = RARRAY_PTR(stmt->defns)[position - 1];
@@ -140,7 +140,7 @@
     ub4 placeholder_len = 0;
     ub4 position = 0;
     oci8_bind_t *obind;
-    const oci8_bind_class_t *bind_class;
+    const oci8_bind_vtable_t *vptr;
     sword status;
     VALUE old_value;
     void *indp;
@@ -167,7 +167,7 @@
     if (obind->base.hp.bnd != NULL) {
         oci8_base_free(&obind->base); /* TODO: OK? */
     }
-    bind_class = (const oci8_bind_class_t *)obind->base.klass;
+    vptr = (const oci8_bind_vtable_t *)obind->base.vptr;
 
     indp = NIL_P(obind->tdo) ? obind->u.inds : NULL;
     if (obind->maxar_sz == 0) {
@@ -176,9 +176,9 @@
         curelep = &obind->curar_sz;
     }
     if (placeholder_ptr == (char*)-1) {
-        status = OCIBindByPos(stmt->base.hp.stmt, &obind->base.hp.bnd, oci8_errhp, position, obind->valuep, obind->value_sz, bind_class->dty, indp, NULL, 0, 0, 0, OCI_DEFAULT);
+        status = OCIBindByPos(stmt->base.hp.stmt, &obind->base.hp.bnd, oci8_errhp, position, obind->valuep, obind->value_sz, vptr->dty, indp, NULL, 0, 0, 0, OCI_DEFAULT);
     } else {
-        status = OCIBindByName(stmt->base.hp.stmt, &obind->base.hp.bnd, oci8_errhp, TO_ORATEXT(placeholder_ptr), placeholder_len, obind->valuep, obind->value_sz, bind_class->dty, indp, NULL, 0, 0, 0, OCI_DEFAULT);
+        status = OCIBindByName(stmt->base.hp.stmt, &obind->base.hp.bnd, oci8_errhp, TO_ORATEXT(placeholder_ptr), placeholder_len, obind->valuep, obind->value_sz, vptr->dty, indp, NULL, 0, 0, 0, OCI_DEFAULT);
     }
     if (status != OCI_SUCCESS) {
         oci8_raise(oci8_errhp, status, stmt->base.hp.stmt);
@@ -191,8 +191,8 @@
     if (NIL_P(obind->tdo) && obind->maxar_sz > 0) {
         oci_lc(OCIBindArrayOfStruct(obind->base.hp.bnd, oci8_errhp, obind->alloc_sz, sizeof(sb2), 0, 0));
     }
-    if (bind_class->post_bind_hook != NULL) {
-        bind_class->post_bind_hook(obind);
+    if (vptr->post_bind_hook != NULL) {
+        vptr->post_bind_hook(obind);
     }
     old_value = rb_hash_aref(stmt->binds, vplaceholder);
     if (!NIL_P(old_value)) {
@@ -276,15 +276,15 @@
     sword rv;
     long idx;
     oci8_bind_t *obind;
-    const oci8_bind_class_t *bind_class;
+    const oci8_bind_vtable_t *vptr;
 
     if (stmt->base.children != NULL) {
         obind = (oci8_bind_t *)stmt->base.children;
         do {
             if (obind->base.type == OCI_HTYPE_DEFINE) {
-                bind_class = (const oci8_bind_class_t *)obind->base.klass;
-                if (bind_class->pre_fetch_hook != NULL) {
-                    bind_class->pre_fetch_hook(obind, stmt->svc);
+                vptr = (const oci8_bind_vtable_t *)obind->base.vptr;
+                if (vptr->pre_fetch_hook != NULL) {
+                    vptr->pre_fetch_hook(obind, stmt->svc);
                 }
             }
             obind = (oci8_bind_t *)obind->base.next;
@@ -610,7 +610,7 @@
     } while (++idx < obind->maxar_sz);
 }
 
-static const oci8_bind_class_t bind_stmt_class = {
+static const oci8_bind_vtable_t bind_stmt_vtable = {
     {
         oci8_bind_hp_obj_mark,
         oci8_bind_free,
@@ -631,7 +631,7 @@
     cOCI8 = rb_define_class("OCI8", cOCIHandle);
     cOCIStmt = rb_define_class_under(cOCI8, "Cursor", cOCIHandle);
 #endif
-    cOCIStmt = oci8_define_class_under(cOCI8, "Cursor", &oci8_stmt_class);
+    cOCIStmt = oci8_define_class_under(cOCI8, "Cursor", &oci8_stmt_vtable);
 
     oci8_sym_select_stmt = ID2SYM(rb_intern("select_stmt"));
     oci8_sym_update_stmt = ID2SYM(rb_intern("update_stmt"));
@@ -668,5 +668,5 @@
     rb_define_private_method(cOCIStmt, "__defined?", oci8_stmt_defined_p, 1);
     rb_define_method(cOCIStmt, "prefetch_rows=", oci8_stmt_set_prefetch_rows, 1);
 
-    oci8_define_bind_class("Cursor", &bind_stmt_class);
+    oci8_define_bind_class("Cursor", &bind_stmt_vtable);
 }