TAO_Notify::Random_File Class Reference

A random file class. More...

#include <Random_File.h>

Inheritance diagram for TAO_Notify::Random_File:

[legend]Collaboration diagram for TAO_Notify::Random_File:

[legend]List of all members.

Public Member Functions
	Random_File ()
	The constructor.
	~Random_File ()
	The destructor, which closes the open file.
bool	open (const ACE_TCHAR *filename, size_t block_size=512)
	Open a file with default permissions.
size_t	block_size () const
ACE_OFF_T	size () const
	Return the current file size, in number of blocks.
bool	write (const size_t block_number, void *buffer, bool atomic=false)
bool	read (const size_t block_number, void *buffer)
	Read a block from our file.
Private Member Functions
bool	seek (const size_t block_number)
	Seek to a given block number, used by reads and writes.
bool	sync ()
	Synchronize the file to disk, used to implement atomic.
Private Attributes
size_t	block_size_
TAO_SYNCH_MUTEX	lock_

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Detailed Description

A random file class.

Derived from ACE_FILE, this class provides access to a file of fixed-size blocks.

Definition at line 45 of file Random_File.h.

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Constructor & Destructor Documentation

TAO_Notify::Random_File::Random_File

(

)

The constructor.

Definition at line 18 of file Random_File.cpp.

  : block_size_(512)
{
}

TAO_Notify::Random_File::~Random_File

(

)

The destructor, which closes the open file.

Definition at line 23 of file Random_File.cpp.

References ACE_FILE::close().

{
  this->close();
}

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Member Function Documentation

size_t TAO_Notify::Random_File::block_size

(

)

const

Accessor for the block size. Note signed size_t is used to be compatible with ACE_FILE.

Definition at line 29 of file Random_File.cpp.

References block_size_.

Referenced by TAO_Notify::Persistent_File_Allocator::block_size(), read(), and write().

{
  return this->block_size_;
}

bool TAO_Notify::Random_File::open	(	const ACE_TCHAR *	filename,
		size_t	block_size = 512
	)

Open a file with default permissions.

Definition at line 51 of file Random_File.cpp.

References ACE_DEBUG, ACE_DEFAULT_FILE_PERMS, ACE_GUARD_RETURN, ACE_TEXT(), ACE_FILE::addr_, block_size_, ACE_FILE::close(), DEBUG_LEVEL, LM_DEBUG, O_BINARY, ACE_OS::open(), ACE_FILE_Addr::set(), ACE_IO_SAP::set_handle(), and TAO_SYNCH_MUTEX.

Referenced by TAO_Notify::Persistent_File_Allocator::open().

{
  ACE_GUARD_RETURN (TAO_SYNCH_MUTEX, ace_mon, this->lock_, false);
  this->block_size_ = block_size;
  bool result = (this->close() == 0);

  if (result)
  {
    if (DEBUG_LEVEL > 8) ACE_DEBUG ((LM_DEBUG,
      ACE_TEXT ("(%P|%t) Opening file %s\n")
      , filename
      ));
    ACE_HANDLE handle = ACE_OS::open(filename,
      O_CREAT | O_RDWR | O_BINARY,
      ACE_DEFAULT_FILE_PERMS);

    if (handle == ACE_INVALID_HANDLE)
    {
      result = false;
    }
    else
    {
      this->set_handle(handle);
      if (this->get_handle() == 0)
      {
        result = false;
      }
      else
      {
        result = (this->addr_.set(filename) == 0);
      }
    }
  }
  return result;
}

bool TAO_Notify::Random_File::read	(	const size_t	block_number,
		void *	buffer
	)

Read a block from our file.

Definition at line 123 of file Random_File.cpp.

References ACE_DEBUG, ACE_GUARD_RETURN, ACE_TEXT(), block_size(), block_size_, DEBUG_LEVEL, LM_DEBUG, ACE_OS::read(), seek(), and TAO_SYNCH_MUTEX.

Referenced by TAO_Notify::Persistent_File_Allocator::read().

{
  ACE_GUARD_RETURN (TAO_SYNCH_MUTEX, ace_mon, this->lock_, false);
  if (DEBUG_LEVEL > 8) ACE_DEBUG ((LM_DEBUG,
    ACE_TEXT ("(%P|%t) Read block %d\n"),
    static_cast<int> (block_number)
    ));
  bool result = this->seek(block_number);
  if (result)
  {
    ssize_t block_size = this->block_size_;
    if (block_size !=
      ACE_OS::read(this->get_handle(), buf, block_size))
    {
      result = false;
    }
  }
  return result;
}

bool TAO_Notify::Random_File::seek

(

const size_t

block_number

)

[private]

Seek to a given block number, used by reads and writes.

Definition at line 144 of file Random_File.cpp.

References block_size_, and ACE_FILE::seek().

Referenced by read(), and write().

{
  ssize_t destloc = block_number * this->block_size_;
  bool result = (destloc == this->ACE_FILE::seek(destloc, SEEK_SET));
  return result;
}

ACE_OFF_T TAO_Notify::Random_File::size

(

)

const

Return the current file size, in number of blocks.

Definition at line 35 of file Random_File.cpp.

References ACE_GUARD_RETURN, block_size_, TAO_SYNCH_MUTEX, and ACE_FILE::tell().

Referenced by TAO_Notify::Persistent_File_Allocator::file_size().

{
  Random_File * const mutable_this = const_cast<Random_File *> (this);
  ACE_GUARD_RETURN (TAO_SYNCH_MUTEX, ace_mon, this->lock_, 0);
  ACE_OFF_T original_pos = mutable_this->tell ();
  mutable_this->ACE_FILE::seek(0, SEEK_END);
  ACE_OFF_T cursize = mutable_this->tell();
  mutable_this->ACE_FILE::seek (original_pos, SEEK_SET);
  if ((cursize % this->block_size_) != 0)
  {
    cursize += this->block_size_;
  }
  return cursize / this->block_size_;
}

bool TAO_Notify::Random_File::sync

(

)

[private]

Synchronize the file to disk, used to implement atomic.

Definition at line 152 of file Random_File.cpp.

References ACE_OS::fsync().

Referenced by write().

{
  bool result = false;
  result = (0 == ACE_OS::fsync(this->get_handle()));
  return result;
}

bool TAO_Notify::Random_File::write	(	const size_t	block_number,
		void *	buffer,
		bool	atomic = false
	)

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.

Definition at line 88 of file Random_File.cpp.

References ACE_DEBUG, ACE_GUARD_RETURN, ACE_TEXT(), block_size(), block_size_, DEBUG_LEVEL, LM_DEBUG, seek(), sync(), TAO_SYNCH_MUTEX, and ACE_OS::write().

Referenced by TAO_Notify::Persistent_File_Allocator::run().

{
  ACE_GUARD_RETURN (TAO_SYNCH_MUTEX, ace_mon, this->lock_, false);
  if (DEBUG_LEVEL > 8) ACE_DEBUG ((LM_DEBUG,
    ACE_TEXT ("(%P|%t) Write block %d %c\n"),
    static_cast<int> (block_number),
    (atomic ? '*' : ' ')
    ));
  bool result = this->seek(block_number);
  if (result)
  {
    if (atomic)
    {
      // sync before so that any block pointed to from this block
      // will be there when this block is written.
      result = sync();
    }
    // ACE uses an ssize_t for buffer size, so we do this to make it happy.
    ssize_t block_size = this->block_size_;
    if (result && (block_size !=
      ACE_OS::write(this->get_handle(), buf, block_size)))
    {
      result = false;
    }
    if (result && atomic)
    {
      // sync after to provide the caller with a guarantee that
      // this block is physically written to the storage device.
      result = sync();
    }
  }
  return result;
}

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Member Data Documentation

size_t TAO_Notify::Random_File::block_size_ [private]

Definition at line 87 of file Random_File.h.

Referenced by block_size(), open(), read(), seek(), size(), and write().

TAO_SYNCH_MUTEX TAO_Notify::Random_File::lock_ [mutable, private]

Definition at line 88 of file Random_File.h.

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The documentation for this class was generated from the following files:

• Random_File.h
• Random_File.cpp

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