From 97916660cebbf590b6c1cdaa586930eca8997b8e Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 10 Sep 2010 12:57:53 +0200
Subject: Add support for result caching

---
 odb/mysql/result.hxx    |  5 ++++-
 odb/mysql/result.txx    |  7 +++++++
 odb/mysql/statement.cxx | 31 +++++++++++++++++++++++++++----
 odb/mysql/statement.hxx |  5 +++++
 4 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/odb/mysql/result.hxx b/odb/mysql/result.hxx
index 812cb68..951ae91 100644
--- a/odb/mysql/result.hxx
+++ b/odb/mysql/result.hxx
@@ -40,9 +40,12 @@ namespace odb
       virtual void
       current (T&);
 
-      void
+      virtual void
       next ();
 
+      virtual void
+      cache ();
+
       using odb::result_impl<T>::current;
 
     private:
diff --git a/odb/mysql/result.txx b/odb/mysql/result.txx
index 9bbdf26..d0a65fa 100644
--- a/odb/mysql/result.txx
+++ b/odb/mysql/result.txx
@@ -73,5 +73,12 @@ namespace odb
         }
       }
     }
+
+    template <typename T>
+    void result_impl<T>::
+    cache ()
+    {
+      statement_->cache ();
+    }
   }
 }
diff --git a/odb/mysql/statement.cxx b/odb/mysql/statement.cxx
index 0cab7cc..df1ce03 100644
--- a/odb/mysql/statement.cxx
+++ b/odb/mysql/statement.cxx
@@ -41,7 +41,9 @@ namespace odb
     query_statement::
     ~query_statement ()
     {
-      if (conn_.active () == this)
+      statement* as (conn_.active ());
+
+      if (cached_ || as == this)
       {
         try
         {
@@ -51,6 +53,9 @@ namespace odb
         {
         }
       }
+
+      if (as == this)
+        conn_.active (0);
     }
 
     query_statement::
@@ -59,6 +64,7 @@ namespace odb
                      binding& image,
                      MYSQL_BIND* parameters)
         : statement (conn),
+          cached_ (false),
           image_ (image),
           image_version_ (0),
           parameters_ (parameters)
@@ -73,6 +79,9 @@ namespace odb
       if (statement* a = conn_.active ())
         a->cancel ();
 
+      if (cached_)
+        free_result ();
+
       if (mysql_stmt_reset (stmt_))
         throw database_exception (stmt_);
 
@@ -105,6 +114,15 @@ namespace odb
       conn_.active (this);
     }
 
+    void query_statement::
+    cache ()
+    {
+      if (mysql_stmt_store_result (stmt_))
+        throw database_exception (stmt_);
+
+      cached_ = true;
+    }
+
     query_statement::result query_statement::
     fetch ()
     {
@@ -152,16 +170,21 @@ namespace odb
     void query_statement::
     free_result ()
     {
+      cached_ = false;
+
       if (mysql_stmt_free_result (stmt_))
         throw database_exception (stmt_);
-
-      conn_.active (0);
     }
 
     void query_statement::
     cancel ()
     {
-      free_result ();
+      // If we cached the result, don't free it just yet.
+      //
+      if (!cached_)
+        free_result ();
+
+      conn_.active (0);
     }
 
     // persist_statement
diff --git a/odb/mysql/statement.hxx b/odb/mysql/statement.hxx
index 05deb4d..bcba2c6 100644
--- a/odb/mysql/statement.hxx
+++ b/odb/mysql/statement.hxx
@@ -86,6 +86,9 @@ namespace odb
       void
       execute ();
 
+      void
+      cache ();
+
       result
       fetch ();
 
@@ -103,6 +106,8 @@ namespace odb
       query_statement& operator= (const query_statement&);
 
     private:
+      bool cached_;
+
       binding& image_;
       std::size_t image_version_;
 
-- 
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