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-rw-r--r--odb/mysql/simple-object-statements.hxx57
1 files changed, 55 insertions, 2 deletions
diff --git a/odb/mysql/simple-object-statements.hxx b/odb/mysql/simple-object-statements.hxx
index c2e9c74..d369313 100644
--- a/odb/mysql/simple-object-statements.hxx
+++ b/odb/mysql/simple-object-statements.hxx
@@ -29,6 +29,58 @@ namespace odb
{
namespace mysql
{
+ // The container_statement_cache class is only defined (and used) in
+ // the generated source file. However, object_statements may be
+ // referenced from another source file in the case of a polymorphic
+ // hierarchy (though in this case the container statement cache is
+ // not used). As a result, we cannot have a by-value member and
+ // instead will store a pointer and lazily allocate the cache if
+ // and when needed. We will also need to store a pointer to the
+ // deleter function which will be initialized during allocation
+ // (at that point we know that the cache class is defined).
+ //
+ template <typename T>
+ struct container_statement_cache_ptr
+ {
+ typedef mysql::connection connection_type;
+
+ container_statement_cache_ptr (): p_ (0) {}
+ ~container_statement_cache_ptr () {if (p_ != 0) (this->*deleter_) (0);}
+
+ T&
+ get (connection_type& c)
+ {
+ if (p_ == 0)
+ allocate (&c);
+
+ return *p_;
+ }
+
+ private:
+ void
+ allocate (connection_type*);
+
+ private:
+ T* p_;
+ void (container_statement_cache_ptr::*deleter_) (connection_type*);
+ };
+
+ template <typename T>
+ void container_statement_cache_ptr<T>::
+ allocate (connection_type* c)
+ {
+ // To reduce object code size, this function acts as both allocator
+ // and deleter.
+ //
+ if (p_ == 0)
+ {
+ p_ = new T (*c);
+ deleter_ = &container_statement_cache_ptr<T>::allocate;
+ }
+ else
+ delete p_;
+ }
+
//
// Implementation for objects with object id.
//
@@ -360,7 +412,7 @@ namespace odb
container_statement_cache_type&
container_statment_cache ()
{
- return container_statement_cache_;
+ return container_statement_cache_.get (conn_);
}
public:
@@ -396,7 +448,8 @@ namespace odb
clear_delayed_ ();
private:
- container_statement_cache_type container_statement_cache_;
+ container_statement_cache_ptr<container_statement_cache_type>
+ container_statement_cache_;
image_type image_;