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

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Version 2.3.1                                    Sun Oct 4 2020                              sc::ShmMemoryGrp(3)

       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.

void*sc::ShmMemoryGrp::obtain_readwrite(distsize_toffset,intsize)[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.

   voidsc::ShmMemoryGrp::release_readwrite(void*data,distsize_toffset,intsize)[virtual]
       This is called when read/write access is no longer needed. The memory will be unlocked.

       Implements sc::MemoryGrp.

   voidsc::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.

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

       #include <memshm.h>

       Inherits sc::MsgMemoryGrp.

   PublicMemberFunctionsShmMemoryGrp (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_toffset, int size)
           Only one thread can have an unreleased obtain_readwrite at a time.
       void * obtain_readonly (distsize_toffset, int size)
           This gives read access to the memory location. No locking is done.
       void * obtain_writeonly (distsize_toffset, int size)
           This gives write access to the memory location. No locking is done.
       void release_readonly (void *data, distsize_toffset, int size)
           This is called when read access is no longer needed.
       void release_writeonly (void *data, distsize_toffset, int size)
           This is called when write access is no longer needed.
       void release_readwrite (void *data, distsize_toffset, 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.

   AdditionalInheritedMembers