NAME

       sc::ShmMemoryGrp - The ShmMemoryGrp concrete class provides an implementation of
       MsgMemoryGrp.

SYNOPSIS

       #include <memshm.h>

       Inherits sc::MsgMemoryGrp.

   Public Member Functions
       ShmMemoryGrp (const Ref< MessageGrp > &msg)
       ShmMemoryGrp (const Ref< KeyVal > &)
       void set_localsize (size_t)
           Set the size of locally held memory.
       void * localdata ()
           Returns a pointer to the local data.
       void * obtain_readwrite (distsize_t offset, int size)
           Only one thread can have an unreleased obtain_readwrite at a time.
       void * obtain_readonly (distsize_t offset, int size)
           This gives read access to the memory location. No locking is done.
       void * obtain_writeonly (distsize_t offset, int size)
           This gives write access to the memory location. No locking is done.
       void release_readonly (void *data, distsize_t offset, int size)
           This is called when read access is no longer needed.
       void release_writeonly (void *data, distsize_t offset, int size)
           This is called when write access is no longer needed.
       void release_readwrite (void *data, distsize_t offset, int size)
           This is called when read/write access is no longer needed.
       void print (std::ostream &o=ExEnv::out0()) const
           Prints out information about the object.

       Public Member Functions inherited from sc::MsgMemoryGrp
       MsgMemoryGrp (const Ref< MessageGrp > &msg)
       MsgMemoryGrp (const Ref< KeyVal > &keyval)
       void sync ()
           Synchronizes all the nodes.

       Public Member Functions inherited from sc::MemoryGrp
       MemoryGrp (const Ref< KeyVal > &)
       int me () const
           Returns who I am.
       int n () const
           Returns how many nodes there are.
       size_t localsize ()
           Returns the amount of memory residing locally on me().
       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 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 * 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.

       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.

       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.

   Additional Inherited Members
       Static Public Member Functions inherited from sc::MemoryGrp
       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 inherited from sc::MemoryGrp
       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 inherited from sc::MsgMemoryGrp
       Ref< MessageGrp > msg_

       Protected Attributes inherited from sc::MemoryGrp
       int me_
       int n_
       distsize_t * offsets_
       int debug_

Detailed Description

       The ShmMemoryGrp concrete class provides an implementation of MsgMemoryGrp.

       It uses SYSV IPC to provided shared memory in a system that provide shared memory in
       hardware. It is very fast and reliable.

Member Function Documentation

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

       Implements sc::MemoryGrp.

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

       Implements sc::MemoryGrp.

   void * sc::ShmMemoryGrp::obtain_readwrite (distsize_t offset, int size) [virtual]
       Only one thread can have an unreleased obtain_readwrite at a time. The actual 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.

       Implements sc::MemoryGrp.

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

       Implements sc::MemoryGrp.

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

       Reimplemented from sc::MemoryGrp.

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

       Implements sc::MemoryGrp.

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

       Implements sc::MemoryGrp.

   void sc::ShmMemoryGrp::release_writeonly (void * data, distsize_t offset, int size) [virtual]
       This is called when write access is no longer needed.

       Implements sc::MemoryGrp.

   void sc::ShmMemoryGrp::set_localsize (size_t) [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.

       Reimplemented from sc::MsgMemoryGrp.

Author

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