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sc::MemoryGrp(3)		      MPQC			sc::MemoryGrp(3)

NAME
     sc::MemoryGrp  -  The  MemoryGrp abstract class provides a way of accessing
     distributed memory in a parallel machine.

SYNOPSIS
     #include <memory.h>

     Inherits sc::DescribedClass.

     Inherited by sc::MsgMemoryGrp, and sc::ProcMemoryGrp.

   Public Member Functions
     MemoryGrp (const Ref< KeyVal > &)
     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 memory.
     size_t localsize ()
	 Returns the amount of memory residing locally on me().
     virtual void * localdata ()=0
	 Returns a pointer to the local data.
     distsize_t localoffset ()
	 Returns the global offset to this node's memory.
     int size (int node)
	 Returns the amount of memory residing on node.
     distsize_t offset (int node)
	 Returns the global offset to node's memory.
     distsize_t totalsize ()
	 Returns the sum of all memory allocated on all nodes.
     virtual void activate ()
	 Activate is called before the memory is to be used.
     virtual void deactivate ()
	 Deactivate is called after the memory has been used.
     virtual void * obtain_writeonly (distsize_t offset, int size)=0
	 This gives write access to the memory 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.
     virtual void * obtain_readonly (distsize_t offset, int size)=0
	 This gives read access to the memory 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.
     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.
     virtual void * malloc_local (size_t nbyte)
	 Allocate data that will be accessed locally only.
     virtual double * malloc_local_double (size_t ndouble)
     virtual void free_local (void *data)
	 Free data that was allocated with malloc_local_double.
     virtual void free_local_double (double *data)
     virtual void catchup ()
	 Processes outstanding requests.
     virtual void print (std::ostream &o=ExEnv::out0()) const
	 Prints out information about the object.

     Public Member Functions inherited from sc::DescribedClass
     DescribedClass (const DescribedClass &)
     DescribedClass & operator= (const DescribedClass &)
     ClassDesc * class_desc () const  throw ()
	 This  returns	the unique pointer to the ClassDesc corresponding to the
	 given type_info object.
     const char * class_name () const
	 Return the name of the object's exact type.
     int class_version () const
	 Return the version of the class.
     virtual void print (std::ostream &=ExEnv::out0()) const
	 Print the object.

     Public Member Functions inherited from sc::RefCount
     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.
     int managed () const
	 Return 1 if the object is managed. Otherwise return 0.

     Public Member Functions inherited from sc::Identity
     Identifier identifier ()
	 Return the Identifier for this argument.

   Static Public Member Functions
     static MemoryGrp * initial_memorygrp (int &argc, char **argv)
	 Create a memory group.
     static MemoryGrp * initial_memorygrp ()
     static void set_default_memorygrp (const Ref< MemoryGrp > &)
	 The default memory group contains the primary memory group to	be  used
	 by an application.
     static MemoryGrp * get_default_memorygrp ()
	 Returns the default memory 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 MemoryGrp abstract class provides a way of accessing distributed memory
     in a parallel machine.

     Several  specializations  are  available.	For one processor, ProcMemoryGrp
     provides a simple stub  implementation.  Parallel	specializations  include
     ShmMemoryGrp,  MTMPIMemoryGrp,  and ARMCIMemoryGrp. The particular special-
     izations that work depend highly on the target hardware and software  envi-
     ronment.

Member Function Documentation
   virtual void sc::MemoryGrp::activate () [virtual]
     Activate is called before the memory is to be used.

     Reimplemented in sc::MTMPIMemoryGrp.

   virtual void sc::MemoryGrp::catchup () [virtual]
     Processes	outstanding  requests.	Some  memory group implementations don't
     have access to real shared memory or even	active	messages.  Instead,  re-
     quests  are  processed  whenever  certain memory 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.

   virtual void sc::MemoryGrp::deactivate () [virtual]
     Deactivate is called after the memory has been used.

     Reimplemented in sc::ARMCIMemoryGrp, and sc::MTMPIMemoryGrp.

   virtual void sc::MemoryGrp::free_local (void * data) [virtual]
     Free data that was allocated with malloc_local_double.

     Reimplemented in sc::ARMCIMemoryGrp.

   static MemoryGrp * sc::MemoryGrp::get_default_memorygrp () [static]
     Returns  the  default memory group. If the default memory group has not yet
     been set, then one is created. The particular specialization used is deter-
     mined by configuration options and which specializations are being used for
     MessageGrp and ThreadGrp.

   static MemoryGrp * sc::MemoryGrp::initial_memorygrp	(int  &  argc,	char  **
     argv) [static]
     Create  a	memory	group. This routine looks for a -memorygrp argument, and
     then the environmental variable MEMORYGRP to decide which specialization of
     MemoryGrp would be appropriate. The argument to -memorygrp or the value  of
     the  environmental variable should be either string for a ParsedKeyVal con-
     structor or a classname.  The  default  ThreadGrp	and  MessageGrp  objects
     should be initialized before this is called.

     References initial_memorygrp().

     Referenced by initial_memorygrp().

   virtual void * sc::MemoryGrp::localdata () [pure virtual]
     Returns a pointer to the local data.

     Implemented  in  sc::ActiveMsgMemoryGrp, sc::ProcMemoryGrp, sc::RDMAMemory-
     Grp, and sc::ShmMemoryGrp.

   virtual void * sc::MemoryGrp::malloc_local (size_t nbyte) [virtual]
     Allocate data that will be accessed locally only. Using this for data  that
     will be used for global operation can improve efficiency. Data allocated in
     this way must be freed with free_local_double.

     Reimplemented in sc::ARMCIMemoryGrp.

   virtual  void  * sc::MemoryGrp::obtain_readonly (distsize_t offset, int size)
     [pure virtual]
     This gives read access to the memory location. No locking is done.

     Implemented in sc::ActiveMsgMemoryGrp,  sc::ProcMemoryGrp,  sc::RDMAMemory-
     Grp, and sc::ShmMemoryGrp.

   virtual  void * sc::MemoryGrp::obtain_readwrite (distsize_t offset, int size)
     [pure virtual]
     Only one thread can have an unreleased obtain_readwrite at a time. The  ac-
     tual  memory region locked can be larger than that requested. If the memory
     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::ActiveMsgMemoryGrp, sc::ProcMemoryGrp, sc::RDMAMemory-
     Grp, and sc::ShmMemoryGrp.

   virtual void * sc::MemoryGrp::obtain_writeonly (distsize_t offset, int  size)
     [pure virtual]
     This gives write access to the memory location. No locking is done.

     Implemented  in  sc::ActiveMsgMemoryGrp, sc::ProcMemoryGrp, sc::RDMAMemory-
     Grp, and sc::ShmMemoryGrp.

   virtual void sc::MemoryGrp::print (std::ostream & o	=  ExEnv::out0())  const
     [virtual]
     Prints out information about the object.

     Reimplemented from sc::DescribedClass.

     Reimplemented  in sc::ActiveMsgMemoryGrp, sc::ARMCIMemoryGrp, sc::RDMAMemo-
     ryGrp, and sc::ShmMemoryGrp.

   virtual void sc::MemoryGrp::release_readonly (void * data, distsize_t offset,
     int size) [pure virtual]
     This is called when read access is no longer needed.

     Implemented in sc::ActiveMsgMemoryGrp,  sc::ProcMemoryGrp,  sc::RDMAMemory-
     Grp, and sc::ShmMemoryGrp.

   virtual  void  sc::MemoryGrp::release_readwrite (void * data, distsize_t off-
     set, int size) [pure virtual]
     This is called when read/write access is no longer needed. The memory  will
     be unlocked.

     Implemented  in  sc::ActiveMsgMemoryGrp, sc::ProcMemoryGrp, sc::RDMAMemory-
     Grp, and sc::ShmMemoryGrp.

   virtual void sc::MemoryGrp::release_writeonly (void * data,	distsize_t  off-
     set, int size) [pure virtual]
     This is called when write access is no longer needed.

     Implemented  in  sc::ActiveMsgMemoryGrp, sc::ProcMemoryGrp, sc::RDMAMemory-
     Grp, and sc::ShmMemoryGrp.

   virtual void sc::MemoryGrp::set_localsize (size_t) [pure virtual]
     Set the size of locally held memory. When memory is accessed using a global
     offset counting starts at node 0 and proceeds up to node n() - 1.

     Implemented in sc::MsgMemoryGrp, sc::RDMAMemoryGrp, sc::ActiveMsgMemoryGrp,
     sc::ARMCIMemoryGrp, sc::ProcMemoryGrp, and sc::ShmMemoryGrp.

   virtual void sc::MemoryGrp::sync () [pure virtual]
     Synchronizes all the nodes. This is useful after remote memory writes to be
     certain that all of the writes have completed and the data can be	accessed
     locally, for example.

     Implemented  in  sc::ARMCIMemoryGrp,  sc::MsgMemoryGrp, sc::MTMPIMemoryGrp,
     and sc::ProcMemoryGrp.

Author
     Generated automatically by Doxygen for MPQC from the source code.

Version 2.3.1			 Thu Sep 3 2026 		sc::MemoryGrp(3)
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