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GNU/Linux |
CentOS 2.1AS(Slurm) |
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pvm_trecv(3) |
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pvm_trecv − Receive with timeout.
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C |
#include <sys/time.h> |
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int bufid = pvm_trecv( int tid, int msgtag, struct timeval *tmout ) |
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Fortran |
call pvmftrecv( tid, msgtag, sec, usec, bufid ) |
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tid |
Integer to match task identifier of sending process. | ||
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msgtag |
Integer to match message tag; should be >= 0. | ||
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tmout |
(or sec and usec) Time to wait before returning without a message. | ||
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bufid |
Integer returns the value of the new active receive buffer identifier. Values less than zero indicate an error. |
The routine pvm_trecv blocks the process until a message with label msgtag has arrived from tid. pvm_trecv then places the message in a new active receive buffer, also clearing the current receive buffer. If no matching message arrives within the specified waiting time, pvm_trecv returns without a message.
A -1 in msgtag or tid matches anything. This allows the user the following options. If tid = -1 then pvm_trecv will accept a message from any process which has a matching msgtag. If msgtag = -1 then pvm_trecv will accept any message that is sent from process tid. If tid and msgtag are both -1, then pvm_trecv will accept any message from any process.
In C, the tmout fields tv_sec and tv_usec specify how long pvm_trecv will wait without returning a matching message. In Fortran, two separate parameters, sec and usec are passed. With both set to zero, pvm_trecv behaves the same as pvm_nrecv, which is to probe for messages and return immediately even if none are matched. In C, passing a null pointer in tmout makes pvm_trecv act like pvm_recv, that is, it will wait indefinitely. In Fortran, setting sec to -1 has the same effect.
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.
If pvm_trecv is successful, bufid will be the new active receive buffer identifier. If no message is received, pvm_trecv returns 0. If some error occurs then bufid will be < 0.
Once pvm_trecv returns, the data in the message can be unpacked into the user’s memory using the unpack routines.
C:
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struct timeval tmout; |
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tid = pvm_parent(); |
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msgtag = 4 ; |
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tmout.tv_sec = 60; |
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tmout.tv_usec = 0; |
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if ((bufid = pvm_trecv( tid, msgtag, &tmout )) > 0) { |
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pvm_upkint( tid_array, 10, 1 ); | |||
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pvm_upkint( problem_size, 1, 1 ); | |||
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pvm_upkfloat( input_array, 100, 1 ); | |||
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} |
Fortran:
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CALL PVMFTRECV( -1, 4, 60, 0, BUFID ) | ||
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IF (BUFID .EQ. 0) GO TO 666 | ||
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CALL PVMFUNPACK( INTEGER4, TIDS, 25, 1, INFO ) | ||
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CALL PVMFUNPACK( REAL8, MATRIX, 100, 100, INFO ) | ||
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666 |
CONTINUE |
These error
conditions can be returned by pvm_trecv
PvmBadParam
giving an invalid tid value, or msgtag < -1.
PvmSysErr
pvmd not responding.
pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_nrecv(3PVM), pvm_recv(3PVM), pvm_unpack(3PVM), pvm_probe(3PVM), pvm_send(3PVM), pvm_mcast(3PVM)
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pvm_trecv(3) | |