sc::FileGrp Class Reference

The FileGrp abstract class provides a way of accessing distributed file in a parallel machine. More...

#include <util/group/file.h>

Inheritance diagram for sc::FileGrp:

Public Member Functions
	FileGrp (const Ref< KeyVal > &)
void	open ()
	Opens the files.
void	close ()
	Closes the files.
void	set_filename (char *name)
	Sets the filename for the FileGrp.
const char *	get_filename () const
	Returns the filename for the FileGrp.
int	me () const
	Returns who I am.
int	n () const
	Returns how many nodes there are.
virtual void	set_localsize (size_t)=0
	Set the size of locally held data. More...
size_t	localsize ()
	Returns the amount of data residing locally on me().
distsize_t	localoffset ()
	Returns the global offset to this node's data.
int	size (int node)
	Returns the amount of data residing on node.
distsize_t	offset (int node)
	Returns the global offset to node's data.
distsize_t	totalsize ()
	Returns the sum of all data allocated on all nodes.
virtual void	activate ()
	Activate is called before the data is to be used.
virtual void	deactivate ()
	Deactivate is called after the data has been used.
virtual void *	obtain_writeonly (distsize_t offset, int size)=0
	This gives write access to the data location. No locking is done.
virtual void *	obtain_readwrite (distsize_t offset, int size)=0
	Only one thread can have an unreleased obtain_readwrite at a time. More...
virtual void *	obtain_readonly (distsize_t offset, int size)=0
	This gives read access to the file location. No locking is done.
virtual void	release_readonly (void *data, distsize_t offset, int size)=0
	This is called when read access is no longer needed.
virtual void	release_writeonly (void *data, distsize_t offset, int size)=0
	This is called when write access is no longer needed.
virtual void	release_readwrite (void *data, distsize_t offset, int size)=0
	This is called when read/write access is no longer needed. More...
virtual void	sum_reduction (double *data, distsize_t doffset, int dsize)
virtual void	sum_reduction_on_node (double *data, size_t doffset, int dsize, int node=-1)
virtual void	sync ()=0
	Synchronizes all the nodes. More...
virtual void	catchup ()
	Processes outstanding requests. More...
virtual void	print (std::ostream &o=ExEnv::out0()) const
	Prints out information about the object.
virtual FileGrp *	clone ()=0
	Clones the given FileGrp. The new FileGrp may need to be initialized additionally.
Public Member Functions inherited from sc::DescribedClass
	DescribedClass (const DescribedClass &)
DescribedClass &	operator= (const DescribedClass &)
ClassDesc *	class_desc () const MPQC__NOEXCEPT
	This returns the unique pointer to the ClassDesc corresponding to the given type_info object. More...
const char *	class_name () const
	Return the name of the object's exact type.
int	class_version () const
	Return the version of the class.
Ref< DescribedClass >	ref ()
	Return this object wrapped up in a Ref smart pointer. More...
Public Member Functions inherited from sc::RefCount
size_t	identifier () const
	Return the unique identifier for this object that can be compared for different objects of different types. More...
int	lock_ptr () const
	Lock this object.
int	unlock_ptr () const
	Unlock this object.
void	use_locks (bool inVal)
	start and stop using locks on this object
refcount_t	nreference () const
	Return the reference count.
refcount_t	reference ()
	Increment the reference count and return the new count.
refcount_t	dereference ()
	Decrement the reference count and return the new count.
int	managed () const
void	unmanage ()
	Turn off the reference counting mechanism for this object. More...

Static Public Member Functions
static FileGrp *	initial_filegrp (int &argc, char **argv)
	Create a file group. More...
static FileGrp *	initial_filegrp ()
static void	set_default_filegrp (const Ref< FileGrp > &)
	The default file group contains the primary file group to be used by an application.
static FileGrp *	get_default_filegrp ()
	Returns the default file group.

Protected Member Functions
void	obtain_local_lock (size_t start, size_t fence)
void	release_local_lock (size_t start, size_t fence)
Protected Member Functions inherited from sc::RefCount
	RefCount (const RefCount &)
RefCount &	operator= (const RefCount &)

Protected Attributes
int	me_
int	n_
distsize_t *	offsets_
int	debug_

Detailed Description

The FileGrp abstract class provides a way of accessing distributed file in a parallel machine.

Several specializations are available. For one processor, ProcFileGrp provides a simple stub implementation. Otherwise, the specializations that should work are MPIIOIFileGrp and MTMPIFileGrp.

If a FileGrp is not given to the program, then one will be automatically chosen depending on which MessageGrp is used by default, the type of machine on which the code was compiled, and what options were given at configuration time.

Member Function Documentation

catchup()

virtual void sc::FileGrp::catchup ( )

virtual

Processes outstanding requests.

Some file group implementations don't have access to real shared memory or even active messages. Instead, requests are processed whenever certain file group routines are called. This can cause large latencies and buffer overflows. If this is a problem, then the catchup member can be called to process all outstanding requests.

initial_filegrp()

static FileGrp* sc::FileGrp::initial_filegrp ( int &  argc, char **  argv  )

static

Create a file group.

This routine looks for a -filegrp argument, then the environmental variable FILEGRP, and, finally, the default MessageGrp object to decide which specialization of FileGrp would be appropriate. The argument to -integralgrp should be either string for a ParsedKeyVal constructor or a classname. The default ThreadGrp and MessageGrp objects should be initialized before this is called.

obtain_readwrite()

virtual void* sc::FileGrp::obtain_readwrite ( distsize_t  offset, int  size  )

pure virtual

Only one thread can have an unreleased obtain_readwrite at a time.

The actual file region locked can be larger than that requested. If the file region is already locked this will block. For this reason, data should be held as read/write for as short a time as possible.

Implemented in sc::ProcFileGrp.

release_readwrite()

virtual void sc::FileGrp::release_readwrite ( void *  data, distsize_t  offset, int  size  )

pure virtual

This is called when read/write access is no longer needed.

The data will be unlocked.

Implemented in sc::ProcFileGrp.

set_localsize()

virtual void sc::FileGrp::set_localsize ( size_t  )

pure virtual

Set the size of locally held data.

When data is accessed using a global offset counting starts at node 0 and proceeds up to node n() - 1.

Implemented in sc::ProcFileGrp.

sync()

virtual void sc::FileGrp::sync ( )

pure virtual

Synchronizes all the nodes.

Consider using this when the way you you access data changes.

Implemented in sc::ProcFileGrp.

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

• src/lib/util/group/file.h