Communicator Management
[Groups, Context and Communicators]

Collaboration diagram for Communicator Management:

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Detailed Description

Funktions for managing communicators.

Because of reasons already stated (see Groups, Context and Communicators) there is no support for user-defined communicators. So this section is limited to functions which return the size of a specific communicator or the rank of the calling process.

Defines
#define	MOC_COMM_NULL   0
	Specifies a null communicator.
#define	MOC_COMM_WORLD   1
	Specifies a constant that contains all of the processes.
#define	MOC_COMM_SELF   2
	Specifies a constant that contains only the calling process.
Typedefs
typedef int	MOC_Comm
	Communicator-Handle.
Functions
int	MOC_Comm_rank (MOC_Comm comm, int *rank)
	Determines the rank of the calling process in the communicator.
int	MOC_Comm_size (MOC_Comm comm, int *size)
	Determines the size of the group associated with a communictor.

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Typedef Documentation

typedef int MOC_Comm

Communicator-Handle.

Masks the actual type which is used to encode the communicator. Char is used and therefore the maximum number of possible communicators is limited to 256. But because there are three predefined communicators (MPI_COMM_NULL, MPI_COMM_WORLD and MPI_COMM_SELF) only 253 user-defined communicators are possible.

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Function Documentation

int MOC_Comm_rank	(	MOC_Comm	comm,
		int *	rank
	)

Determines the rank of the calling process in the communicator.

Parameters:

	comm	in commicator-handle
	rank	out rank of the calling process in group of comm

Return values:

	MOC_SUCCESS	No error; MPI routine completed successfully.
	MOC_ERR_COMM	Invalid communicator. A common error is to use a null communicator in a call.

int MOC_Comm_size	(	MOC_Comm	comm,
		int *	size
	)

Determines the size of the group associated with a communictor.

Parameters:

	comm	in commicator-handle
	size	out number of processes in the group of comm

Return values:

	MOC_SUCCESS	No error; MPI routine completed successfully.
	MOC_ERR_COMM	Invalid communicator. A common error is to use a null communicator in a call.