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// -*- C++ -*-
//=============================================================================
/**
* @file Storable_File_Guard.h
*
* @author Rich Seibel (seibelr@ociweb.com)
* @author Byron Harris (harrisb@ociweb.com)
*/
//=============================================================================
#ifndef TAO_STORABLE_FILE_GUARD_H
#define TAO_STORABLE_FILE_GUARD_H
#include "tao/Storable_Base.h"
TAO_BEGIN_VERSIONED_NAMESPACE_DECL
namespace TAO
{
/**
* @class Storable_File_Guard
* @brief Base class to use with TAO_Storable_Base to synch object state
* with a storable base.
*
* A guard for Storable_Base that opens a file
* for read/write and sets a lock on it. It then checks if the file has
* changed and re-reads it if it has.
*
*/
class TAO_Export Storable_File_Guard
{
public:
Storable_File_Guard (bool redundant,
bool use_backup = Storable_Base::use_backup_default);
virtual ~Storable_File_Guard () noexcept(false);
/// Releases the lock, closes the file, and deletes the I/O stream.
/// Destructors of derived classes should call this this will
/// virtual functions are available.
void release ();
/// Return when the object in memory has last changed
virtual time_t get_object_last_changed () = 0;
/// Get the underlying stream being used.
TAO::Storable_Base & peer ();
/// Indicate how the state of the object is being used.
/// This is used for determine the mode for accessing
/// the persistent store.
enum Method_Type
{
/// Construction with persistent file already existing
CREATE_WITH_FILE,
/// Construction with persistent file not existing
CREATE_WITHOUT_FILE,
/// Getting object state
ACCESSOR,
/// Setting object state
MUTATOR
};
protected:
/// Should be called by constructors of derived classes
/// since can't call the virtual functions below in constructor
/// of this class.
void init (Method_Type method_type);
/// Initializes the backing store file object but does not
/// actually load the data. This can be called without locks,
/// allowing the caller to decide whether or not to then lock
/// and complete the load.
void init_no_load (Method_Type method_type);
/// Complete the initialization of the containing object, should
/// be called with lock held after calling init_no_load
void reload ();
/// Check if the object is current with the last update.
virtual bool object_obsolete ();
/// Mark the object as up to date
virtual void mark_object_current ();
/// Indicate when the object in memory has last changed
virtual void set_object_last_changed (const time_t & time) = 0;
/// Load object from file to memory. Return 0 on success.
virtual int load_from_stream () = 0;
/// Answer if object has been loaded from file
virtual bool is_loaded_from_stream () = 0;
virtual Storable_Base * create_stream (const char * mode) = 0;
/// The pointer to the actual file I/O (bridge pattern)
Storable_Base *fl_;
private:
// Return 0 if successful.
int load ();
bool redundant_;
/// A flag to keep us from trying to close things more than once.
int closed_;
/// The flags that we were opened with
int rwflags_;
/// A flag indicating if backup/restore should be performed
bool use_backup_;
/// Symbolic values for the flags in the above
enum { mode_write = 1, mode_read = 2, mode_create = 4 };
};
}
TAO_END_VERSIONED_NAMESPACE_DECL
#endif
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