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/* -*- C++ -*- */
//=============================================================================
/**
* @file Dump.h
*
* $Id$
*
*
* 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).
*
* The macros which allow easy registration and removal of objects to be
* dumped (ACE_REGISTER_OBJECT and ACE_REMOVE_OBJECT) are turned into
* no-ops by compiling with the ACE_NDEBUG macro defined. This allows
* usage to be removed in "release mode" builds without changing code.
*
* 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.
*
*
* @author Doug Schmidt
*/
//=============================================================================
#ifndef ACE_DUMP_H
#define ACE_DUMP_H
#include /**/ "ace/pre.h"
#include "ace/Synch.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
/**
* @class ACE_Dumpable
*
* @brief Base class that defines a uniform interface for all object
* dumping.
*/
class ACE_Export ACE_Dumpable
{
public:
friend class ACE_ODB;
friend class ACE_Dumpable_Ptr;
/// Constructor.
ACE_Dumpable (const void *);
/// This pure virtual method must be filled in by a subclass.
virtual void dump (void) const = 0;
protected:
virtual ~ACE_Dumpable (void);
private:
/// Pointer to the object that is being stored.
const void *this_;
};
/**
* @class ACE_Dumpable_Ptr
*
* @brief A smart pointer stored in the in-memory object database
* ACE_ODB. The pointee (if any) is deleted when reassigned.
*/
class ACE_Export ACE_Dumpable_Ptr
{
public:
ACE_Dumpable_Ptr (const ACE_Dumpable *dumper = 0);
const ACE_Dumpable *operator->() const;
void operator= (const ACE_Dumpable *dumper) const;
private:
/// "Real" pointer to the underlying abstract base class
/// pointer that does the real work.
const ACE_Dumpable *dumper_;
};
/**
* @class ACE_ODB
*
* @brief This is the object database (ODB) that keeps track of all
* live ACE objects.
*/
class ACE_Export ACE_ODB
{
public:
/// @todo This is clearly inadequate and should be dynamic...
enum {MAX_TABLE_SIZE = 100000};
/// Iterates through the entire set of registered objects and
/// dumps their state.
void dump_objects (void);
/// Add the tuple <dumper, this_> to the list of registered ACE objects.
void register_object (const ACE_Dumpable *dumper);
/// Use <this_> to locate and remove the associated <dumper> from the
/// list of registered ACE objects.
void remove_object (const void *this_);
/// Interface to the Singleton instance of the object database.
static ACE_ODB *instance (void);
private:
ACE_ODB (void); // Ensure we have a Singleton...
struct Tuple
{
/// Pointer to the object that is registered.
const void *this_;
/// Smart pointer to the ACE_Dumpable object associated with this_.
/// This uses an ACE_Dumpable_Ptr, instead of a bare pointer, to
/// cope with hierarchies of dumpable classes. In such cases we
/// typically want only one dump, corresponding to the most derived
/// instance. To achieve this, the handle registered for the
/// subobject corresponding to the base class is destroyed (hence
/// on destruction of the subobject its handle won't exist anymore
/// and we'll have to check for that).
const ACE_Dumpable_Ptr dumper_;
Tuple (void) : dumper_(0) {}
};
/// Singleton instance of this class.
static ACE_ODB *instance_;
/// The current implementation is very simple-minded and will be
/// changed to be dynamic.
Tuple object_table_[ACE_ODB::MAX_TABLE_SIZE];
/// Current size of <object_table_>.
int current_size_;
};
// Include the templates classes at this point.
#include "ace/Dump_T.h"
#include /**/ "ace/post.h"
#endif /* ACE_DUMP_H */
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