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/* -*- C++ -*- */
//=============================================================================
/**
* @file Random_File.h
*
* $Id$
*
* This class implements a a random-access file containing
* fixed-size blocks.
*
* @author Jonathan Pollack <pollack_j@ociweb.com>
*/
//=============================================================================
#ifndef RANDOM_FILE_H
#define RANDOM_FILE_H
#include /**/ "ace/pre.h"
#include /**/ "ace/config-all.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
#pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#include "notify_serv_export.h"
#include "ace/FILE.h"
#include "ace/streams.h"
#include "ace/Synch_T.h"
namespace TAO_Notify
{
/**
* \brief A random file class.
*
* Derived from ACE_FILE, this class provides access to a
* file of fixed-size blocks.
*
*/
class TAO_Notify_Serv_Export Random_File : public ACE_FILE
{
public:
/// The constructor.
Random_File();
/// The destructor, which closes the open file.
~Random_File();
/// Open a file with default permissions.
bool open(const char* filename, size_t block_size = 512);
/// Accessor for the block size.
/// Note signed size_t is used to be compatible with
/// ACE_FILE.
size_t block_size() const;
/// Return the current file size, in number of blocks.
size_t size() const;
/// Write a block to our file, potentially as an "atomic" write.
/// If the atomic argument is true, then the operating system's
/// write-through cache for this file is flushed both before and
/// after the write.
/// The flush before ensures that any record pointers in this block
/// will point to records that actually appear in the file.
/// The flush after provides the caller with a guarantee that
/// the data will appear in the file even if the system fails
/// immediately after this method returns.
bool write(const size_t block_number, void* buffer, bool atomic = false);
/// Read a block from our file.
bool read(const size_t block_number, void* buffer);
private:
/// Seek to a given block number, used by reads and writes.
bool seek(const size_t block_number);
/// Synchronize the file to disk, used to implement atomic.
bool sync();
private:
size_t block_size_;
ACE_SYNCH_MUTEX lock_;
};
} /* namespace TAO_Notify */
#include /**/ "ace/post.h"
#endif /* RANDOM_FILE_H */
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