The new functions that are replacements for the MPI-1 functions for caching on communicators are:
| MPI_COMM_CREATE_KEYVAL(comm_copy_attr_fn, comm_delete_attr_fn, comm_keyval, extra_state) | |
| IN comm_copy_attr_fn | copy callback function for comm_keyval (function) | 
| IN comm_delete_attr_fn | delete callback function for comm_keyval (function) | 
| OUT comm_keyval | key value for future access (integer) | 
| IN extra_state | extra state for callback functions | 
 
  int MPI_Comm_create_keyval(MPI_Comm_copy_attr_function *comm_copy_attr_fn, MPI_Comm_delete_attr_function *comm_delete_attr_fn, int *comm_keyval, void *extra_state) 
  
 
  MPI_COMM_CREATE_KEYVAL(COMM_COPY_ATTR_FN, COMM_DELETE_ATTR_FN, COMM_KEYVAL, EXTRA_STATE, IERROR)
 EXTERNAL COMM_COPY_ATTR_FN, COMM_DELETE_ATTR_FN
INTEGER COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE 
  
 
  
  static int MPI::Comm::Create_keyval(MPI::Comm::Copy_attr_function* comm_copy_attr_fn, MPI::Comm::Delete_attr_function* comm_delete_attr_fn, void* extra_state) 
  
  
  
This function replaces MPI_KEYVAL_CREATE, whose use is deprecated. The C binding is identical. The Fortran binding differs in that extra_state is an address-sized integer. Also, the copy and delete callback functions have Fortran bindings that are consistent with address-sized attributes.
The argument comm_copy_attr_fn may be specified as MPI_COMM_NULL_COPY_FN or MPI_COMM_DUP_FN from either C, C++, or Fortran. MPI_COMM_NULL_COPY_FN is a function that does nothing other than returning flag = 0 and MPI_SUCCESS. MPI_COMM_DUP_FN is a simple-minded copy function that sets flag = 1, returns the value of attribute_val_in in attribute_val_out, and returns MPI_SUCCESS. These replace the MPI-1 predefined callbacks MPI_NULL_COPY_FN and MPI_DUP_FN, whose use is deprecated.
The argument comm_delete_attr_fn may be specified as MPI_COMM_NULL_DELETE_FN from either C, C++, or Fortran. MPI_COMM_NULL_DELETE_FN is a function that does nothing, other than returning MPI_SUCCESS. MPI_COMM_NULL_DELETE_FN replaces MPI_NULL_DELETE_FN, whose use is deprecated.
The C callback functions are:
 
  
  typedef int MPI_Comm_copy_attr_function(MPI_Comm oldcomm, int comm_keyval, void *extra_state, void *attribute_val_in, void *attribute_val_out, int *flag); 
  
and
 
  typedef int MPI_Comm_delete_attr_function(MPI_Comm comm, int comm_keyval, void *attribute_val, void *extra_state); 
  
  
which are the same as the MPI-1.1 calls but with a new name. The old names are deprecated.
The Fortran callback functions are:
 
  SUBROUTINE COMM_COPY_ATTR_FN(OLDCOMM, COMM_KEYVAL, EXTRA_STATE, ATTRIBUTE_VAL_IN, ATTRIBUTE_VAL_OUT, FLAG, IERROR)
 INTEGER OLDCOMM, COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) EXTRA_STATE, ATTRIBUTE_VAL_IN,
    ATTRIBUTE_VAL_OUT
LOGICAL FLAG 
  
and
 
  SUBROUTINE COMM_DELETE_ATTR_FN(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, EXTRA_STATE, IERROR)
 INTEGER COMM, COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL, EXTRA_STATE 
  
The C++ callbacks are:
 
  
  typedef int MPI::Comm::Copy_attr_function(const MPI::Comm& oldcomm, int comm_keyval, void* extra_state, void* attribute_val_in, void* attribute_val_out, bool& flag); 
  
and
 
  typedef int MPI::Comm::Delete_attr_function(MPI::Comm& comm, int comm_keyval, void* attribute_val, void* extra_state); 
  
  
  
| MPI_COMM_FREE_KEYVAL(comm_keyval) | |
| INOUT comm_keyval | key value (integer) | 
 
  int MPI_Comm_free_keyval(int *comm_keyval) 
  
 
  MPI_COMM_FREE_KEYVAL(COMM_KEYVAL, IERROR)
 INTEGER COMM_KEYVAL, IERROR 
   
 
  static void MPI::Comm::Free_keyval(int& comm_keyval) 
  
This call is identical to the MPI-1 call MPI_KEYVAL_FREE but is needed to match the new communicator-specific creation function. The use of MPI_KEYVAL_FREE is deprecated.
| MPI_COMM_SET_ATTR(comm, comm_keyval, attribute_val) | |
| INOUT comm | communicator from which attribute will be attached (handle) | 
| IN comm_keyval | key value (integer) | 
| IN attribute_val | attribute value | 
 
  int MPI_Comm_set_attr(MPI_Comm comm, int comm_keyval, void *attribute_val) 
  
 
 
  MPI_COMM_SET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, IERROR)
 INTEGER COMM, COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL 
   
 
  void MPI::Comm::Set_attr(int comm_keyval, const void* attribute_val) const 
  
  
This function replaces MPI_ATTR_PUT, whose use is deprecated. The C binding is identical. The Fortran binding differs in that attribute_val is an address-sized integer.
| MPI_COMM_GET_ATTR(comm, comm_keyval, attribute_val, flag) | |
| IN comm | communicator to which the attribute is attached (handle) | 
| IN comm_keyval | key value (integer) | 
| OUT attribute_val | attribute value, unless flag = false | 
| OUT flag | false if no attribute is associated with the key (logical) | 
 
  int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval, void *attribute_val, int *flag) 
  
 
  MPI_COMM_GET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, FLAG, IERROR)
 INTEGER COMM, COMM_KEYVAL, IERROR
INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL
LOGICAL FLAG 
    
 
  bool MPI::Comm::Get_attr(int comm_keyval, void* attribute_val) const 
  
This function replaces MPI_ATTR_GET, whose use is deprecated. The C binding is identical. The Fortran binding differs in that attribute_val is an address-sized integer.
| MPI_COMM_DELETE_ATTR(comm, comm_keyval) | |
| INOUT comm | communicator from which the attribute is deleted (handle) | 
| IN comm_keyval | key value (integer) | 
 
  int MPI_Comm_delete_attr(MPI_Comm comm, int comm_keyval) 
  
 
  
  MPI_COMM_DELETE_ATTR(COMM, COMM_KEYVAL, IERROR)
 INTEGER COMM, COMM_KEYVAL, IERROR 
    
  
 
  
  void MPI::Comm::Delete_attr(int comm_keyval) 
  
  
This function is the same as MPI_ATTR_DELETE but is needed to match the new communicator specific functions. The use of MPI_ATTR_DELETE is deprecated.