#include <ace/Dump.h>
class ACE_ODB {
public:
enum {MAX_TABLE_SIZE = 100000};
void dump_objects (void);
void register_object (const ACE_Dumpable *dumper);
void remove_object (const void *this_);
static ACE_ODB *instance (void);
private:
ACE_ODB (void);
struct Tuple {
public:
const void *this_;
const ACE_Dumpable_Ptr dumper_;
inline Tuple();
};
static ACE_ODB *instance_;
Tuple object_table_[ACE_ODB::MAX_TABLE_SIZE];
int current_size_;
};
A prototype mechanism that allow all ACE objects to be registered with a central in-memory "database" that can dump the state of all live ACE objects (e.g., from within a debugger).
To turn on this feature simply compile with -DACE_NDEBUG
There are several interesting aspects to this design:
1. It uses the External Polymorphism pattern to avoid having to derive all ACE classes from a common base class that has virtual methods (this is crucial to avoid unnecessary overhead). In addition, there is no additional space added to ACE objects (this is crucial to maintain binary layout compatibility).
2. This mechanism can be conditionally compiled in order to completely disable this feature entirely. Moreover, by using macros there are relatively few changes to ACE code.
3. This mechanism copes with single-inheritance hierarchies of dumpable classes. In such cases we typically want only one dump, corresponding to the most derived instance. Thanks to Christian Millour (chris@etca.fr) for illustrating how to do this. Note, however, that this scheme doesn't generalize to work with multiple-inheritance or virtual base classes.
Future work includes:
1. Using a dynamic object table rather than a static table
2. Adding support to allow particular classes of objects to be selectively dumped.
void dump_objects (void);
void register_object (const ACE_Dumpable *dumper);
dumper, this_
to the list of registered ACE objects.
void remove_object (const void *this_);
this_
to locate and remove the associated dumper
from the
list of registered ACE objects.
static ACE_ODB *instance (void);
ACE_ODB (void);
static ACE_ODB *instance_;
Tuple object_table_[ACE_ODB::MAX_TABLE_SIZE];
int current_size_;
object_table_
.