casacore
Public Member Functions | Protected Member Functions | Protected Attributes | Private Member Functions | List of all members
casacore::MultiFileBase Class Referenceabstract

Abstract base class to combine multiple files in a single one. More...

#include <MultiFileBase.h>

Public Member Functions

 MultiFileBase (const String &name, Int blockSize=0)
 Open or create a MultiFileBase with the given name. More...
 
virtual ~MultiFileBase ()
 The destructor flushes and closes the file. More...
 
Int fileId (const String &name, Bool throwExcp=True) const
 Return the file id of a file in the MultiFileBase object. More...
 
Int addFile (const String &name)
 Add a file to the MultiFileBase object. More...
 
void deleteFile (Int fileId)
 Delete a file. More...
 
Int64 read (Int fileId, void *buffer, Int64 size, Int64 offset)
 Read a block at the given offset. More...
 
Int64 write (Int fileId, const void *buffer, Int64 size, Int64 offset)
 Write a block at the given offset. More...
 
void flush ()
 Flush the file by writing all dirty data and all header info. More...
 
void resync ()
 Resync with another process by clearing the buffers and rereading the header. More...
 
virtual void reopenRW ()=0
 Reopen the underlying file for read/write access. More...
 
virtual void fsync ()=0
 Fsync the file (i.e., force the data to be physically written). More...
 
String fileName () const
 Get the file name of the MultiFileBase. More...
 
Bool isWritable () const
 Is the file writable? More...
 
Int64 blockSize () const
 Get the block size used. More...
 
uInt nfile () const
 Get the nr of virtual files. More...
 
Int64 size () const
 Get the total nr of data blocks used. More...
 
const vector< MultiFileInfo > & info () const
 Get the info object (for test purposes mainly). More...
 
const vector< Int64 > & freeBlocks () const
 Get the free blocks (for test purposes mainly). More...
 

Protected Member Functions

void setNewFile ()
 Set the flags and blockSize for a new MultiFile/HDF5. More...
 

Protected Attributes

String itsName
 
Int64 itsBlockSize
 
Int64 itsNrBlock
 
Int64 itsHdrCounter
 
vector< MultiFileInfoitsInfo
 
Bool itsWritable
 
Bool itsChanged
 
vector< Int64itsFreeBlocks
 

Private Member Functions

void writeDirty (MultiFileInfo &info)
 
virtual void doAddFile (MultiFileInfo &)=0
 Do the class-specific actions on adding a file. More...
 
virtual void doDeleteFile (MultiFileInfo &)=0
 Do the class-specific actions on deleting a file. More...
 
virtual void flushFile ()=0
 Flush the file itself. More...
 
virtual void close ()=0
 Flush and close the file. More...
 
virtual void writeHeader ()=0
 Write the header info. More...
 
virtual void readHeader (Bool always=True)=0
 Read the header info. More...
 
virtual void extend (MultiFileInfo &info, Int64 lastblk)=0
 Extend the virtual file to fit lastblk. More...
 
virtual void writeBlock (MultiFileInfo &info, Int64 blknr, const void *buffer)=0
 Write a data block. More...
 
virtual void readBlock (MultiFileInfo &info, Int64 blknr, void *buffer)=0
 Read a data block. More...
 

Detailed Description

Abstract base class to combine multiple files in a single one.

Intended use:

Public interface

Review Status

Test programs:
tMultiFile

Synopsis

This class is a container file holding multiple virtual files. It is primarily meant as a container file for the storage manager files of a table to reduce the number of files used (especially for Lustre) and to reduce the number of open files (especially when concatenating tables).
A secondary goal is offering the ability to use an IO buffer size that matches the file system well (large buffer size for e.g. ZFS).

The SetupNewTable constructor has a StorageOption argument to define if a MultiFile has to be used and if so, the buffer size to use. It is also possible to specify that through aipsrc variables.

A virtual file is spread over multiple (fixed size) data blocks in the MultiFile. A data block is never shared by multiple files. For each virtual file MultiFile keeps a MultiFileInfo object telling the file size and the blocks numbers used for the file. When flushing the MultiFile, this meta info is written into a header block and, if needed, continuation blocks. On open and resync, it is read back.

A virtual file is represented by an MFFileIO object, which is derived from ByteIO and as such part of the casacore IO framework. It makes it possible for applications to access a virtual file in the same way as a regular file.

It is possible to delete a virtual file. Its blocks will be added to the free block list (which is also stored in the meta info).

Example

In principle it is possible to use the MultiFile functions directly. However, in general it is much easier to use an MFFileIO object per virtual file as shown below.

// Create a new MultiFile using a block size of 1 MB.
MultiFile mfile("file.mf', ByteIO::New, 1048576);
// Create a virtual file in it.
MFFileIO mf1(mfile, "mf1", ByteIO::New);
// Use it (for example) as the sink of AipsIO.
AipsIO stream (&mf1);
// Write values.
stream << (Int)10;
stream << True;
// Seek to beginning of file and read data in.
stream.setpos (0);
Int vali;
Bool valb;
stream >> vali >> valb;

To Do

Definition at line 134 of file MultiFileBase.h.

Constructor & Destructor Documentation

casacore::MultiFileBase::MultiFileBase ( const String name,
Int  blockSize = 0 
)

Open or create a MultiFileBase with the given name.

Upon creation the block size can be given. If 0, it uses the block size of the file system the file is on.

virtual casacore::MultiFileBase::~MultiFileBase ( )
virtual

The destructor flushes and closes the file.

Member Function Documentation

Int casacore::MultiFileBase::addFile ( const String name)

Add a file to the MultiFileBase object.

It returns the file id. Only the base name of the given file name is used. In this way the MultiFileBase container file can be moved.

Int64 casacore::MultiFileBase::blockSize ( ) const
inline

Get the block size used.

Definition at line 189 of file MultiFileBase.h.

virtual void casacore::MultiFileBase::close ( )
privatepure virtual

Flush and close the file.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

void casacore::MultiFileBase::deleteFile ( Int  fileId)

Delete a file.

It adds its blocks to the free block list.

virtual void casacore::MultiFileBase::doAddFile ( MultiFileInfo )
privatepure virtual

Do the class-specific actions on adding a file.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

virtual void casacore::MultiFileBase::doDeleteFile ( MultiFileInfo )
privatepure virtual

Do the class-specific actions on deleting a file.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

virtual void casacore::MultiFileBase::extend ( MultiFileInfo info,
Int64  lastblk 
)
privatepure virtual

Extend the virtual file to fit lastblk.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

Int casacore::MultiFileBase::fileId ( const String name,
Bool  throwExcp = True 
) const

Return the file id of a file in the MultiFileBase object.

If the name is unknown, an exception is thrown if throwExcp is set. Otherwise it returns -1.

String casacore::MultiFileBase::fileName ( ) const
inline

Get the file name of the MultiFileBase.

Definition at line 181 of file MultiFileBase.h.

void casacore::MultiFileBase::flush ( )

Flush the file by writing all dirty data and all header info.

virtual void casacore::MultiFileBase::flushFile ( )
privatepure virtual

Flush the file itself.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

const vector<Int64>& casacore::MultiFileBase::freeBlocks ( ) const
inline

Get the free blocks (for test purposes mainly).

Definition at line 204 of file MultiFileBase.h.

virtual void casacore::MultiFileBase::fsync ( )
pure virtual

Fsync the file (i.e., force the data to be physically written).

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

const vector<MultiFileInfo>& casacore::MultiFileBase::info ( ) const
inline

Get the info object (for test purposes mainly).

Definition at line 200 of file MultiFileBase.h.

Bool casacore::MultiFileBase::isWritable ( ) const
inline

Is the file writable?

Definition at line 185 of file MultiFileBase.h.

uInt casacore::MultiFileBase::nfile ( ) const

Get the nr of virtual files.

Int64 casacore::MultiFileBase::read ( Int  fileId,
void *  buffer,
Int64  size,
Int64  offset 
)

Read a block at the given offset.

It returns the actual size read.

virtual void casacore::MultiFileBase::readBlock ( MultiFileInfo info,
Int64  blknr,
void *  buffer 
)
privatepure virtual

Read a data block.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

virtual void casacore::MultiFileBase::readHeader ( Bool  always = True)
privatepure virtual

Read the header info.

If always==False, the info is only read if the header counter has changed.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

virtual void casacore::MultiFileBase::reopenRW ( )
pure virtual

Reopen the underlying file for read/write access.

Nothing will be done if the file is writable already. Otherwise it will be reopened and an exception will be thrown if it is not possible to reopen it for read/write access.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

void casacore::MultiFileBase::resync ( )

Resync with another process by clearing the buffers and rereading the header.

The header is only read if its counter has changed.

void casacore::MultiFileBase::setNewFile ( )
protected

Set the flags and blockSize for a new MultiFile/HDF5.

Int64 casacore::MultiFileBase::size ( ) const
inline

Get the total nr of data blocks used.

Definition at line 196 of file MultiFileBase.h.

Int64 casacore::MultiFileBase::write ( Int  fileId,
const void *  buffer,
Int64  size,
Int64  offset 
)

Write a block at the given offset.

It returns the actual size written.

virtual void casacore::MultiFileBase::writeBlock ( MultiFileInfo info,
Int64  blknr,
const void *  buffer 
)
privatepure virtual

Write a data block.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

void casacore::MultiFileBase::writeDirty ( MultiFileInfo info)
inlineprivate
virtual void casacore::MultiFileBase::writeHeader ( )
privatepure virtual

Write the header info.

Implemented in casacore::MultiFile, and casacore::MultiHDF5.

Member Data Documentation

Int64 casacore::MultiFileBase::itsBlockSize
protected

Definition at line 242 of file MultiFileBase.h.

Bool casacore::MultiFileBase::itsChanged
protected

Definition at line 247 of file MultiFileBase.h.

vector<Int64> casacore::MultiFileBase::itsFreeBlocks
protected

Definition at line 248 of file MultiFileBase.h.

Int64 casacore::MultiFileBase::itsHdrCounter
protected

Definition at line 244 of file MultiFileBase.h.

vector<MultiFileInfo> casacore::MultiFileBase::itsInfo
protected

Definition at line 245 of file MultiFileBase.h.

String casacore::MultiFileBase::itsName
protected

Definition at line 241 of file MultiFileBase.h.

Int64 casacore::MultiFileBase::itsNrBlock
protected

Definition at line 243 of file MultiFileBase.h.

Bool casacore::MultiFileBase::itsWritable
protected

Definition at line 246 of file MultiFileBase.h.


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