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/* -*- C++ -*- */
// $Id$
// ============================================================================
//
// = LIBRARY
// ace
//
// = FILENAME
// Dump.h
//
// = DESCRIPTION
//
// 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.
//
// = AUTHOR
// Doug Schmidt
//
// ============================================================================
#ifndef ACE_DUMP_H
#define ACE_DUMP_H
#include "ace/Synch.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
class ACE_Export ACE_Dumpable
{
// = TITLE
// Base class that defines a uniform interface for all object
// dumping.
public:
friend class ACE_ODB;
friend class ACE_Dumpable_Ptr;
ACE_Dumpable (const void *);
// Constructor.
virtual void dump (void) const = 0;
// This pure virtual method must be filled in by a subclass.
protected:
virtual ~ACE_Dumpable (void);
private:
const void *this_;
// Pointer to the object that is being stored.
};
class ACE_Export ACE_Dumpable_Ptr
{
// = TITLE
// A smart pointer stored in the in-memory object database
// ACE_ODB. The pointee (if any) is deleted when reassigned.
public:
ACE_Dumpable_Ptr (const ACE_Dumpable *dumper = 0);
const ACE_Dumpable *operator->() const;
void operator= (const ACE_Dumpable *dumper) const;
private:
const ACE_Dumpable *dumper_;
// "Real" pointer to the underlying abstract base class
// pointer that does the real work.
};
class ACE_Export ACE_ODB
{
// = TITLE
// This is the object database (ODB) that keeps track of all
// live ACE objects.
public:
enum {MAX_TABLE_SIZE = 100000}; // This is clearly inadequate and should be dynamic...
void dump_objects (void);
// Iterates through the entire set of registered objects and
// dumps their state.
void register_object (const ACE_Dumpable *dumper);
// Add the tuple <dumper, this_> to the list of registered ACE objects.
void remove_object (const void *this_);
// Use <this_> to locate and remove the associated <dumper> from the
// list of registered ACE objects.
static ACE_ODB *instance (void);
// Interface to the Singleton instance of the object database.
private:
ACE_ODB (void); // Ensure we have a Singleton...
struct Tuple
{
const void *this_;
// Pointer to the object that is registered.
const ACE_Dumpable_Ptr dumper_;
// 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).
Tuple() : dumper_(0) {}
};
static ACE_ODB *instance_;
// Singleton instance of this class.
Tuple object_table_[ACE_ODB::MAX_TABLE_SIZE];
// The current implementation is very simple-minded and will be
// changed to be dynamic.
int current_size_;
// Current size of <object_table_>.
};
// Include the templates classes at this point.
#include "ace/Dump_T.h"
#endif /* ACE_DUMP_H */
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