GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 2.1AS(Slurm) |
|
 |
pvmfnrecv(3) |
 |
pvm_nrecv − Non-blocking receive.
|
C |
int bufid = pvm_nrecv( int tid, int msgtag ) |
|||
|
Fortran |
call pvmfnrecv( tid, msgtag, bufid ) |
|
tid |
Integer task identifier of sending process supplied by the user. | ||
|
msgtag |
Integer message tag supplied by the user. msgtag should be >= 0. | ||
|
bufid |
Integer returning the value of the new active receive buffer identifier. Values less than zero indicate an error. |
The routine pvm_nrecv checks to see if a message with label msgtag has arrived from tid. and also clears the current receive buffer if any, If a matching message has arrived pvm_nrecv immediately places the message in a new active receive buffer, and returns the buffer identifier in bufid.
If the requested message has not arrived, then pvm_nrecv immediately returns with a 0 in bufid. If some error occurs bufid will be < 0.
A -1 in msgtag or tid matches anything. This allows the user the following options. If tid = -1 and msgtag is defined by the user, then pvm_nrecv will accept a message from any process which has a matching msgtag. If msgtag = -1 and tid is defined by the user, then pvm_nrecv will accept any message that is sent from process tid. If tid = -1 and msgtag = -1, then pvm_nrecv will accept any message from any process.
The PVM model guarantees the following about message order. If task 1 sends message A to task 2, then task 1 sends message B to task 2, message A will arrive at task 2 before message B. Moreover, if both messages arrive before task 2 does a receive, then a wildcard receive will always return message A.
pvm_nrecv is non-blocking in the sense that the routine always returns immediately either with the message or with the information that the message has not arrived at the local pvmd yet. pvm_nrecv can be called multiple times to check if a given message has arrived yet. In addition the blocking receive pvm_recv can be called for the same message if the application runs out of work it could do before the data arrives.
If pvm_nrecv returns with the message, then the data in the message can be unpacked into the user’s memory using the unpack routines.
C:
|
tid = pvm_parent(); |
|||
|
msgtag = 4 ; |
|||
|
arrived = pvm_nrecv( tid, msgtag ); |
|||
|
if ( arrived > 0) |
|||
|
info = pvm_upkint( tid_array, 10, 1 ); | |||
|
else |
|||
|
/* go do other computing */ |
Fortran:
|
CALL PVMFNRECV( -1, 4, ARRIVED ) | ||
|
IF ( ARRIVED .gt. 0 ) THEN | ||
|
CALL PVMFUNPACK( INTEGER4, TIDS, 25, 1, INFO ) | ||
|
CALL PVMFUNPACK( REAL8, MATRIX, 100, 100, INFO ) | ||
|
ELSE | ||
|
* |
GO DO USEFUL WORK | |
|
ENDIF |
These error
conditions can be returned by pvm_nrecv.
PvmBadParam
giving an invalid tid value or msgtag.
PvmSysErr
pvmd not responding.
pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_recv(3PVM), pvm_unpack(3PVM), pvm_send(3PVM), pvm_mcast(3PVM)
|
pvmfnrecv(3) | |