Implement uniform handle management across all databases

Also use the auto_handle template instead of the raw handle in connection,
statement, and result classes. This removes a lot of brittle "exception
safety guarantee" code that we had in those classes.

1 files changed, 92 insertions, 0 deletions

diff --git a/odb/pgsql/auto-handle.hxx b/odb/pgsql/auto-handle.hxx
new file mode 100644
index 0000000..2ed58e5
--- /dev/null
+++ b/odb/pgsql/auto-handle.hxx
@@ -0,0 +1,92 @@
+// file      : odb/pgsql/auto-handle.hxx
+// author    : Constantin Michael <constantin@codesynthesis.com>
+// copyright : Copyright (c) 2005-2011 Code Synthesis Tools CC
+// license   : GNU GPL v2; see accompanying LICENSE file
+
+#ifndef ODB_PGSQL_AUTO_HANDLE_HXX
+#define ODB_PGSQL_AUTO_HANDLE_HXX
+
+#include <odb/pre.hxx>
+
+#include <odb/pgsql/version.hxx>
+#include <odb/pgsql/pgsql-fwd.hxx> // PGconn, PGresult
+
+#include <odb/pgsql/details/export.hxx>
+
+namespace odb
+{
+  namespace pgsql
+  {
+    template <typename H>
+    struct handle_traits;
+
+    template <>
+    struct LIBODB_PGSQL_EXPORT handle_traits<PGconn>
+    {
+      static void
+      release (PGconn*);
+    };
+
+    template <>
+    struct LIBODB_PGSQL_EXPORT handle_traits<PGresult>
+    {
+      static void
+      release (PGresult*);
+    };
+
+    template <typename H>
+    class auto_handle
+    {
+    public:
+      auto_handle (H* h = 0)
+          : h_ (h)
+      {
+      }
+
+      ~auto_handle ()
+      {
+        if (h_ != 0)
+          handle_traits<H>::release (h_);
+      }
+
+      H*
+      get () const
+      {
+        return h_;
+      }
+
+      void
+      reset (H* h = 0)
+      {
+        if (h_ != 0)
+          handle_traits<H>::release (h_);
+
+        h_ = h;
+      }
+
+      H*
+      release ()
+      {
+        H* h (h_);
+        h_ = 0;
+        return h;
+      }
+
+      operator H* ()
+      {
+        return h_;
+      }
+
+    private:
+      auto_handle (const auto_handle&);
+      auto_handle& operator= (const auto_handle&);
+
+    private:
+      H* h_;
+    };
+  }
+}
+
+#include <odb/post.hxx>
+
+#endif // ODB_PGSQL_AUTO_HANDLE_HXX