pvm_freebuf(3pvm) [debian man page]

FREEBUF(3PVM)							  PVM Version 3.4						     FREEBUF(3PVM)

NAME

       pvm_freebuf - Disposes of a message buffer.

SYNOPSIS

       C    int info = pvm_freebuf( int bufid )

       Fortran	 call pvmffreebuf( bufid, info )

PARAMETERS

       bufid   Integer message buffer identifier.

       info    Integer status code returned by the routine.  Values less than zero indicate an error.

DESCRIPTION

       The routine pvm_freebuf frees the memory associated with the message buffer identified by bufid.  Message buffers are created by pvm_mkbuf,
       pvm_initsend, and pvm_recv.  If pvm_freebuf is successful, info will be 0.  If some error occurs then info will be < 0.

       pvm_freebuf can be called for a send buffer created by pvm_mkbuf after the message has been sent and is no longer needed.

       Receive buffers typically do not have to be freed unless they have been saved in the course of using multiple buffers.  But pvm_freebuf can
       be  used  to  destroy  receive buffers as well.	So messages that arrive but are no longer needed can be destroyed so they will not consume
       buffer space.

       Typically multiple send and receive buffers are not needed and the user can simply use the pvm_initsend routine to reset the  default  send
       buffer.

       There  are  several  cases  where multiple buffers are useful.  One example where multiple message buffers are needed involves libraries or
       graphical interfaces that use PVM and interact with a running PVM application but do not want to interfere with the application's own  com-
       munication.

       When  multiple  buffers	are  used  they generally are made and freed for each message that is packed.  In fact, pvm_initsend simply does a
       pvm_freebuf followed by a pvm_mkbuf for the default buffer.

EXAMPLES

       C:
	    bufid = pvm_mkbuf( PvmDataDefault );
		  :
	    info = pvm_freebuf( bufid );

       Fortran:
	    CALL PVMFMKBUF( PVMDEFAULT, BUFID )
		  :
	    CALL PVMFFREEBUF( BUFID, INFO )

ERRORS

       These error conditions can be returned by pvm_freebuf

       PvmBadParam
	      giving an invalid argument value.

       PvmNoSuchBuf
	      giving an invalid bufid value.

SEE ALSO

       pvm_mkbuf(3PVM), pvm_initsend(3PVM), pvm_recv(3PVM)

								  30 August, 1993						     FREEBUF(3PVM)

MKBUF(3PVM)							  PVM Version 3.4						       MKBUF(3PVM)

NAME

       pvm_mkbuf - Creates a new message buffer.

SYNOPSIS

       C    int bufid = pvm_mkbuf( int encoding )

       Fortran	 call pvmfmkbuf( encoding, bufid )

PARAMETERS

       encoding
	       Integer specifying the buffer's encoding scheme.
	       Options in C are:
		    Encoding value	     MEANING
		    PvmDataDefault	0    XDR
		    PvmDataRaw		1    no encoding
		    PvmDataInPlace	2    data left in place

	       Option names in Fortran are:
		    Encoding value	     MEANING
		    PVMDEFAULT		0    XDR
		    PVMRAW		1    no encoding
		    PVMINPLACE		2    data left in place

       bufid   Integer message buffer identifier returned.  Values less than zero indicate an error.

DESCRIPTION

       The routine pvm_mkbuf creates a new message buffer and sets its encoding status to encoding.  If pvm_mkbuf is successful, bufid will be the
       identifier for the new buffer, which can be used as a send buffer.  If some error occurs then bufid will be < 0.

       With the default setting XDR encoding is used when packing the message because PVM can not know if the user is going to add a heterogeneous
       machine before this message is sent.  The other options to encoding allow the user to take advantage of knowledge about his virtual machine
       even when it is heterogeneous. For example, if the user knows that the next message will only be sent to a  machine  that  understands  the
       native format, then he can use PvmDataRaw encoding and save on encoding costs.

       PvmDataInPlace  encoding  specifies  that data be left in place during packing.	The message buffer only contains the sizes and pointers to
       the items to be sent. When pvm_send is called the items are copied directly out of the user's memory. This option decreases the	number	of
       times  a  message is copied at the expense of requiring the user to not modify the items between the time they are packed and the time they
       are sent.

       pvm_mkbuf is required if the user wishes to manage multiple message buffers and should be used in conjunction with pvm_freebuf.	 pvm_free-
       buf should be called for a send buffer after a message has been sent and is no longer needed.

       Receive	buffers are created automatically by the pvm_recv and pvm_nrecv routines and do not have to be freed unless they have been explic-
       itly saved with pvm_setrbuf.

       Typically multiple send and receive buffers are not needed and the user can simply use the pvm_initsend routine to reset the  default  send
       buffer.

       There  are  several  cases  where multiple buffers are useful.  One example where multiple message buffers are needed involves libraries or
       graphical interfaces that use PVM and interact with a running PVM application but do not want to interfere with the application's own  com-
       munication.

       When multiple buffers are used they generally are made and freed for each message that is packed.

RESTRICTIONS

       PvmDataInPlace  allows  only  dense (stride = 1) data in version 3.3.  It cannot be used on shared memory (*MP) architectures; a PvmNotImpl
       error will occur at send time.

EXAMPLES

       C:
	    bufid = pvm_mkbuf( PvmDataRaw );
	    /* send message */
	    info = pvm_freebuf( bufid );

       Fortran:
	    CALL PVMFMKBUF(PVMDEFAULT, MBUF)
       *    SEND MESSAGE HERE
	    CALL PVMFFREEBUF( MBUF, INFO )

ERRORS

       These error conditions can be returned by pvm_mkbuf
	    PvmBadParam    giving an invalid encoding value.
	    PvmNoMem	   Malloc has failed. There is not enough memory
			   to create the buffer

SEE ALSO

       pvm_initsend(3PVM), pvm_freebuf(3PVM)

								  30 August, 1993						       MKBUF(3PVM)