Comm
Date: 2015-04-18

mpi

## Class Comm

- java.lang.Object
- - mpi.Comm

- Direct Known Subclasses:
    Intercomm, Intracomm

      public class Comm
      extends java.lang.Object

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `Group` | `group`
    `mpjdev.Comm` | `mpjdevComm`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `Abort(int errorcode)` Abort MPI.
    `void` | `Attr_delete(int keyval)` Retrieves attribute value by key.
    `java.lang.Object` | `Attr_get(int keyval)` Retrieves attribute value by key.
    `Prequest` | `Bsend_init(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Creates a persistent communication request for a buffered mode send.
    `void` | `Bsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Send in buffered mode.
    `protected void` | `bsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `java.lang.Object` | `clone()` Duplicate this communicator.
    `static int` | `Compare(Comm comm1, Comm comm2)` Compare two communicators.
    `Intercomm` | `Create_intercomm(Comm local_comm, int local_leader, int remote_leader, int tag)` Create an inter-communicator.
    `void` | `Free()` Destroy this communicator.
    `Group` | `Group()` Return group associated with a communicator.
    `Request` | `Ibsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Start a buffered mode, nonblocking send.
    `protected Request` | `ibsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `Status` | `Iprobe(int source, int tag)` Check if there is an incoming message matching the pattern specified.
    `Request` | `Irecv(java.lang.Object buf, int offset, int count, Datatype datatype, int src, int tag)` Start a nonblocking receive.
    `protected Request` | `irecv(java.lang.Object buf, int offset, int count, Datatype datatype, int src, int tag, boolean pt2pt)`
    `Request` | `Irsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Start a ready mode, nonblocking send.
    `protected Request` | `irsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `Request` | `Isend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Start a standard mode, nonblocking send.
    `protected Request` | `isend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `Request` | `Issend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Start a synchronous mode, nonblocking send.
    `protected Request` | `issend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `int` | `Pack_size(int incount, Datatype datatype)` Returns an upper bound on the increment of `position` effected by `pack`.
    `int` | `Pack(java.lang.Object inbuf, int offset, int incount, Datatype datatype, mpjbuf.Buffer outbuf, int position)` Packs message in send buffer `inbuf` into space specified in `outbuf`.
    `Status` | `Probe(int source, int tag)` Wait until there is an incoming message matching the pattern specified.
    `int` | `Rank()` Rank of this process in group of this communicator.
    `Prequest` | `Recv_init(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Creates a persistent communication request for a receive operation.
    `Status` | `Recv(java.lang.Object buf, int offset, int count, Datatype datatype, int source, int tag)` Blocking receive operation.
    `protected Status` | `recv(java.lang.Object buf, int offset, int count, Datatype datatype, int source, int tag, boolean pt2pt)`
    `Prequest` | `Rsend_init(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Creates a persistent communication request for a ready mode send.
    `void` | `Rsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Send in ready mode.
    `protected void` | `rsend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `Prequest` | `Send_init(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Creates a persistent communication request for a standard mode send.
    `void` | `Send(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Blocking send operation.
    `protected void` | `send(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `Status` | `Sendrecv_replace(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int sendtag, int source, int recvtag)` Execute a blocking send and receive operation, receiving message into send buffer.
    `protected Status` | `sendrecv(java.lang.Object sendbuf, int sendoffset, int sendcount, Datatype sendtype, int dest, int sendtag, java.lang.Object recvbuf, int recvoffset, int recvcount, Datatype recvtype, int source, int recvtag)`
    `Status` | `Sendrecv(java.lang.Object sendbuf, int sendoffset, int sendcount, Datatype sendtype, int dest, int sendtag, java.lang.Object recvbuf, int recvoffset, int recvcount, Datatype recvtype, int source, int recvtag)` Execute a blocking send and receive operation.
    `int` | `Size()` Size of group of this communicator.
    `Prequest` | `Ssend_init(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Creates a persistent communication request for a synchronous mode send.
    `void` | `Ssend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag)` Send in synchronous mode.
    `protected void` | `ssend(java.lang.Object buf, int offset, int count, Datatype datatype, int dest, int tag, boolean pt2pt)`
    `boolean` | `Test_inter()` Test if this communicator is an inter-communicator.
    `int` | `Topo_test()` Returns the type of topology associated with the communicator.
    `int` | `Unpack(mpjbuf.Buffer inbuf, int position, java.lang.Object outbuf, int offset, int outcount, Datatype datatype)` Unpacks message in receive buffer `outbuf` into space specified in `inbuf`.

    - ### Methods inherited from class java.lang.Object

      `equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### group

          public Group group

    - #### mpjdevComm

          public mpjdev.Comm mpjdevComm

  - ### Method Detail

    - #### Size

          public int Size()
                   throws MPIException

      Size of group of this communicator.

      returns: | number of processors in the group of this communicator

      Java binding of the MPI operation `MPI_COMM_SIZE`.

      Throws:
        `MPIException`

    - #### Rank

          public int Rank()
                   throws MPIException

      Rank of this process in group of this communicator.

      returns: | rank of the calling process in the group of this communicator

      Java binding of the MPI operation `MPI_COMM_RANK`.

      Throws:
        `MPIException`

    - #### Group

          public Group Group()
                      throws MPIException

      Return group associated with a communicator.

      returns: | group corresponding to this communicator group

      Java binding of the MPI operation `MPI_COMM_GROUP`.

      Throws:
        `MPIException`

    - #### Compare

          public static int Compare(Comm comm1,
                    Comm comm2)
                             throws MPIException

      Compare two communicators.

      `comm1` | first communicator
      `comm2` | second communicator
      returns: | result

      Java binding of the MPI operation `MPI_COMM_COMPARE`.

      `MPI.IDENT`(0) results if the `comm1` and `comm2` are references to the same object (ie, if `comm1 == comm2`). `MPI.CONGRUENT`(3) results if the underlying groups are identical but the communicators differ by context. `MPI.SIMILAR`(1) results if the underlying groups are similar but the communicators differ by context. `MPI.UNEQUAL`(2) results otherwise.

      Throws:
        `MPIException`

    - #### Free

          public void Free()
                    throws MPIException

      Destroy this communicator.

      Java binding of the MPI operation `MPI_COMM_FREE`.

      Throws:
        `MPIException`

    - #### Test_inter

          public boolean Test_inter()
                             throws MPIException

      Test if this communicator is an inter-communicator.

      returns: | `true` if this is an inter-communicator, `false` otherwise

      Java binding of the MPI operation `MPI_COMM_TEST_INTER`.

      Throws:
        `MPIException`

    - #### Create_intercomm

          public Intercomm Create_intercomm(Comm local_comm,
                                   int local_leader,
                                   int remote_leader,
                                   int tag)
                                     throws MPIException

      Create an inter-communicator.

      `local_comm` | local intra-communicator
      `local_leader` | rank of local group leader in `localComm`
      `remote_leader` | rank of remote group leader in this communictor
      `tag` | ``safe'' tag
      returns: | new inter-communicator

      Java binding of the MPI operation `MPI_INTERCOMM_CREATE`.

      (This operation is defined as a method on the ``peer communicator'', making it analogous to a `send` or `recv` communication with the remote group leader.)

      Throws:
        `MPIException`

    - #### Attr_get

          public java.lang.Object Attr_get(int keyval)
                                    throws MPIException

      Retrieves attribute value by key.

      `keyval` | one of the key values predefined by the implementation
      returns: | attribute value

      Java binding of the MPI operation `MPI_ATTR_GET`.

      Throws:
        `MPIException`

    - #### Attr_delete

          public void Attr_delete(int keyval)
                           throws MPIException

      Retrieves attribute value by key.

      `keyval` | one of the key values predefined by the implementation
      returns: | attribute value

      Java binding of the MPI operation `MPI_ATTR_GET`.

      Throws:
        `MPIException`

    - #### Send

          public void Send(java.lang.Object buf,
                  int offset,
                  int count,
                  Datatype datatype,
                  int dest,
                  int tag)
                    throws MPIException

      Blocking send operation.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag

      Java binding of the MPI operation `MPI_SEND`.

      The actual argument associated with `buf` must be one-dimensional array. The value `offset` is a subscript in this array, defining the position of the first item of the message.

      If the `datatype` argument represents an MPI basic type, its value must agree with the element type of `buf`---either a primitive type or a reference (object) type. If the `datatype` argument represents an MPI derived type, its base type must agree with the element type of `buf`

      Throws:
        `MPIException`

    - #### send

          protected void send(java.lang.Object buf,
                  int offset,
                  int count,
                  Datatype datatype,
                  int dest,
                  int tag,
                  boolean pt2pt)
                       throws MPIException

      Throws:
        `MPIException`

    - #### Ssend

          public void Ssend(java.lang.Object buf,
                   int offset,
                   int count,
                   Datatype datatype,
                   int dest,
                   int tag)
                     throws MPIException

      Send in synchronous mode.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag

      Java binding of the MPI operation `MPI_SSEND`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### ssend

          protected void ssend(java.lang.Object buf,
                   int offset,
                   int count,
                   Datatype datatype,
                   int dest,
                   int tag,
                   boolean pt2pt)
                        throws MPIException

      Throws:
        `MPIException`

    - #### Bsend

          public void Bsend(java.lang.Object buf,
                   int offset,
                   int count,
                   Datatype datatype,
                   int dest,
                   int tag)
                     throws MPIException

      Send in buffered mode.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag

      Java binding of the MPI operation `MPI_BSEND`.

      This operation copies message into a buffer (mpi.Buffer) specified by MPI.Buffer_attach operation, and then sends using the standard mode of communication. Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### bsend

          protected void bsend(java.lang.Object buf,
                   int offset,
                   int count,
                   Datatype datatype,
                   int dest,
                   int tag,
                   boolean pt2pt)
                        throws MPIException

      Throws:
        `MPIException`

    - #### Rsend

          public void Rsend(java.lang.Object buf,
                   int offset,
                   int count,
                   Datatype datatype,
                   int dest,
                   int tag)
                     throws MPIException

      Send in ready mode.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag

      Java binding of the MPI operation `MPI_RSEND`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### rsend

          protected void rsend(java.lang.Object buf,
                   int offset,
                   int count,
                   Datatype datatype,
                   int dest,
                   int tag,
                   boolean pt2pt)
                        throws MPIException

      Throws:
        `MPIException`

    - #### Isend

          public Request Isend(java.lang.Object buf,
                      int offset,
                      int count,
                      Datatype datatype,
                      int dest,
                      int tag)
                        throws MPIException

      Start a standard mode, nonblocking send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | communication request

      Java binding of the MPI operation `MPI_ISEND`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### isend

          protected Request isend(java.lang.Object buf,
                      int offset,
                      int count,
                      Datatype datatype,
                      int dest,
                      int tag,
                      boolean pt2pt)
                           throws MPIException

      Throws:
        `MPIException`

    - #### Ibsend

          public Request Ibsend(java.lang.Object buf,
                       int offset,
                       int count,
                       Datatype datatype,
                       int dest,
                       int tag)
                         throws MPIException

      Start a buffered mode, nonblocking send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | communication request

      Java binding of the MPI operation `MPI_IBSEND`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### ibsend

          protected Request ibsend(java.lang.Object buf,
                       int offset,
                       int count,
                       Datatype datatype,
                       int dest,
                       int tag,
                       boolean pt2pt)
                            throws MPIException

      Throws:
        `MPIException`

    - #### Issend

          public Request Issend(java.lang.Object buf,
                       int offset,
                       int count,
                       Datatype datatype,
                       int dest,
                       int tag)
                         throws MPIException

      Start a synchronous mode, nonblocking send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | communication request

      Java binding of the MPI operation `MPI_ISSEND`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### issend

          protected Request issend(java.lang.Object buf,
                       int offset,
                       int count,
                       Datatype datatype,
                       int dest,
                       int tag,
                       boolean pt2pt)
                            throws MPIException

      Throws:
        `MPIException`

    - #### Irsend

          public Request Irsend(java.lang.Object buf,
                       int offset,
                       int count,
                       Datatype datatype,
                       int dest,
                       int tag)
                         throws MPIException

      Start a ready mode, nonblocking send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | communication request

      Java binding of the MPI operation `MPI_IRSEND`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### irsend

          protected Request irsend(java.lang.Object buf,
                       int offset,
                       int count,
                       Datatype datatype,
                       int dest,
                       int tag,
                       boolean pt2pt)
                            throws MPIException

      Throws:
        `MPIException`

    - #### Recv

          public Status Recv(java.lang.Object buf,
                    int offset,
                    int count,
                    Datatype datatype,
                    int source,
                    int tag)
                      throws MPIException

      Blocking receive operation.

      `buf` | receive buffer array
      `offset` | initial offset in receive buffer
      `count` | number of items in receive buffer
      `datatype` | datatype of each item in receive buffer
      `source` | rank of source
      `tag` | message tag
      returns: | status object

      Java binding of the MPI operation `MPI_RECV`.

      The actual argument associated with `buf` must be one-dimensional array. The value `offset` is a subscript in this array, defining the position into which the first item of the incoming message will be copied.

      If the `datatype` argument represents an MPI basic type, its value must agree with the element type of `buf`---either a primitive type or a reference (object) type. If the `datatype` argument represents an MPI derived type, its base type must agree with the element type of `buf`

      Throws:
        `MPIException`

    - #### recv

          protected Status recv(java.lang.Object buf,
                    int offset,
                    int count,
                    Datatype datatype,
                    int source,
                    int tag,
                    boolean pt2pt)
                         throws MPIException

      Throws:
        `MPIException`

    - #### Irecv

          public Request Irecv(java.lang.Object buf,
                      int offset,
                      int count,
                      Datatype datatype,
                      int src,
                      int tag)
                        throws MPIException

      Start a nonblocking receive.

      `buf` | receive buffer array
      `offset` | initial offset in receive buffer
      `count` | number of items in receive buffer
      `datatype` | datatype of each item in receive buffer
      `source` | rank of source
      `tag` | message tag
      returns: | communication request

      Java binding of the MPI operation `MPI_IRECV`.

      Further comments as for `Recv`.

      Throws:
        `MPIException`

    - #### irecv

          protected Request irecv(java.lang.Object buf,
                      int offset,
                      int count,
                      Datatype datatype,
                      int src,
                      int tag,
                      boolean pt2pt)
                           throws MPIException

      Throws:
        `MPIException`

    - #### Iprobe

          public Status Iprobe(int source,
                      int tag)
                        throws MPIException

      Check if there is an incoming message matching the pattern specified.

      `source` | rank of source
      `tag` | message tag
      returns: | status object or null handle

      Java binding of the MPI operation `MPI_IPROBE`.

      If such a message is currently available, a status object similar to the return value of a matching `Recv` operation is returned. Otherwise a null handle is returned.

      Throws:
        `MPIException`

    - #### Probe

          public Status Probe(int source,
                     int tag)
                       throws MPIException

      Wait until there is an incoming message matching the pattern specified.

      `source` | rank of source
      `tag` | message tag
      returns: | status object

      Java binding of the MPI operation `MPI_PROBE`.

      Returns a status object similar to the return value of a matching `Recv` operation.

      Throws:
        `MPIException`

    - #### Pack_size

          public int Pack_size(int incount,
                      Datatype datatype)
                        throws MPIException

      Returns an upper bound on the increment of `position` effected by `pack`.

      `incount` | number of items in input buffer
      `datatype` | datatype of each item in input buffer
      returns: | upper bound on size of packed message

      Java binding of the MPI operation `MPI_PACK_SIZE`.

      It is an error to call this function if the base type of `datatype` is `MPI.OBJECT`.

      Throws:
        `MPIException`

    - #### Pack

          public int Pack(java.lang.Object inbuf,
                 int offset,
                 int incount,
                 Datatype datatype,
                 mpjbuf.Buffer outbuf,
                 int position)
                   throws MPIException

      Packs message in send buffer `inbuf` into space specified in `outbuf`.

      `inbuf` | input buffer array
      `offset` | initial offset in input buffer
      `incount` | number of items in input buffer
      `datatype` | datatype of each item in input buffer
      `outbuf` | output buffer
      `position` | initial position in output buffer
      returns: | final position in output buffer

      Java binding of the MPI operation `MPI_PACK`.

      The return value is the output value of `position` - the inital value incremented by the number of bytes written.

      Throws:
        `MPIException`

    - #### Unpack

          public int Unpack(mpjbuf.Buffer inbuf,
                   int position,
                   java.lang.Object outbuf,
                   int offset,
                   int outcount,
                   Datatype datatype)
                     throws MPIException

      Unpacks message in receive buffer `outbuf` into space specified in `inbuf`.

      `inbuf` | input buffer
      `position` | initial position in input buffer
      `outbuf` | output buffer array
      `offset` | initial offset in output buffer
      `outcount` | number of items in output buffer
      `datatype` | datatype of each item in output buffer
      returns: | final position in input buffer

      Java binding of the MPI operation `MPI_UNPACK`.

      The return value is the output value of `position` - the inital value incremented by the number of bytes read.

      Throws:
        `MPIException`

    - #### Bsend_init

          public Prequest Bsend_init(java.lang.Object buf,
                            int offset,
                            int count,
                            Datatype datatype,
                            int dest,
                            int tag)
                              throws MPIException

      Creates a persistent communication request for a buffered mode send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | persistent communication request

      Java binding of the MPI operation `MPI_BSEND_INIT`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### Send_init

          public Prequest Send_init(java.lang.Object buf,
                           int offset,
                           int count,
                           Datatype datatype,
                           int dest,
                           int tag)
                             throws MPIException

      Creates a persistent communication request for a standard mode send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | persistent communication request

      Java binding of the MPI operation `MPI_SEND_INIT`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### Ssend_init

          public Prequest Ssend_init(java.lang.Object buf,
                            int offset,
                            int count,
                            Datatype datatype,
                            int dest,
                            int tag)
                              throws MPIException

      Creates a persistent communication request for a synchronous mode send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | persistent communication request

      Java binding of the MPI operation `MPI_SSEND_INIT`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### Rsend_init

          public Prequest Rsend_init(java.lang.Object buf,
                            int offset,
                            int count,
                            Datatype datatype,
                            int dest,
                            int tag)
                              throws MPIException

      Creates a persistent communication request for a ready mode send.

      `buf` | send buffer array
      `offset` | initial offset in send buffer
      `count` | number of items to send
      `datatype` | datatype of each item in send buffer
      `dest` | rank of destination
      `tag` | message tag
      returns: | persistent communication request

      Java binding of the MPI operation `MPI_RSEND_INIT`.

      Further comments as for `Send`.

      Throws:
        `MPIException`

    - #### Recv_init

          public Prequest Recv_init(java.lang.Object buf,
                           int offset,
                           int count,
                           Datatype datatype,
                           int dest,
                           int tag)
                             throws MPIException

      Creates a persistent communication request for a receive operation.

      `buf` | receive buffer array
      `offset` | initial offset in receive buffer
      `count` | number of items in receive buffer
      `datatype` | datatype of each item in receive buffer
      `source` | rank of source
      `tag` | message tag
      returns: | communication request

      Java binding of the MPI operation `MPI_RECV_INIT`.

      Further comments as for `Recv`.

      Throws:
        `MPIException`

    - #### Sendrecv

          public Status Sendrecv(java.lang.Object sendbuf,
                        int sendoffset,
                        int sendcount,
                        Datatype sendtype,
                        int dest,
                        int sendtag,
                        java.lang.Object recvbuf,
                        int recvoffset,
                        int recvcount,
                        Datatype recvtype,
                        int source,
                        int recvtag)
                          throws MPIException

      Execute a blocking send and receive operation.

      `sendbuf` | send buffer array
      `sendoffset` | initial offset in send buffer
      `sendcount` | number of items to send
      `sendtype` | datatype of each item in send buffer
      `dest` | rank of destination
      `sendtag` | send tag
      `recvbuf` | receive buffer array
      `recvoffset` | initial offset in receive buffer
      `recvcount` | number of items in receive buffer
      `recvtype` | datatype of each item in receive buffer
      `source` | rank of source
      `recvtag` | receive tag
      returns: | status object

      Java binding of the MPI operation `MPI_SENDRECV`.

      Further comments as for `Send` and `Recv`.

      Throws:
        `MPIException`

    - #### Sendrecv_replace

          public Status Sendrecv_replace(java.lang.Object buf,
                                int offset,
                                int count,
                                Datatype datatype,
                                int dest,
                                int sendtag,
                                int source,
                                int recvtag)
                                  throws MPIException

      Execute a blocking send and receive operation, receiving message into send buffer.

      `buf` | buffer array
      `offset` | initial offset in buffer
      `count` | number of items to send
      `type` | datatype of each item in buffer
      `dest` | rank of destination
      `sendtag` | send tag
      `source` | rank of source
      `recvtag` | receive tag
      returns: | status object

      Further comments as for `Send` and `Recv`.

      Throws:
        `MPIException`

    - #### sendrecv

          protected Status sendrecv(java.lang.Object sendbuf,
                        int sendoffset,
                        int sendcount,
                        Datatype sendtype,
                        int dest,
                        int sendtag,
                        java.lang.Object recvbuf,
                        int recvoffset,
                        int recvcount,
                        Datatype recvtype,
                        int source,
                        int recvtag)
                             throws MPIException

      Throws:
        `MPIException`

    - #### Topo_test

          public int Topo_test()
                        throws MPIException

      Returns the type of topology associated with the communicator.

      returns: | topology type of communicator

      Java binding of the MPI operation `MPI_TOPO_TEST`.

      The return value will be one of `MPI.GRAPH`, `MPI.CART` or `MPI.UNDEFINED`.

      Throws:
        `MPIException`

    - #### Abort

          public void Abort(int errorcode)
                     throws MPIException

      Abort MPI.

      `errorcode` | error code for Unix or POSIX environments

      Java binding of the MPI operation `MPI_ABORT`.

      Throws:
        `MPIException`

    - #### clone

          public java.lang.Object clone()
                                 throws MPIException

      Duplicate this communicator.

      returns: | copy of this communicator

      Java binding of the MPI operation `MPI_COMM_DUP`.

      The new communicator is ``congruent'' to the old one, but has a different context.

      Overrides:
        `clone` in class `java.lang.Object`
      Throws:
        `MPIException`