Freeing Library Resources in User Mode
In the MT User mode, service procedures must invoke svc_done() before returning. svc_done() frees resources allocated to service a client request directed to the specified service transport handle. This function is invoked after a client request has been serviced, or after an error or abnormal condition that prevents a reply from being sent. After svc_done() is invoked, the service transport handle should not be referenced by the service procedure. Example 4-41 shows a server in MT User mode.
Note -
svc_done() must only be called within MT User mode. For more information on this call, see the rpc_svc_calls(3NSL) man page.
Example 4-41 MT User Mode: rpc_test.h
#define SVC2_PROG 0x30000002
#define SVC2_VERS 1
#define SVC2_PROC_ADD 1)
#define SVC2_PROC_MULT 2
struct intpair {
u_short a;
u_short b;
};
typedef struct intpair intpair;
struct svc2_add_args {
int argument;
SVCXPRT *transp;
};
struct svc2_mult_args {
intpair mult_argument;
SVCXPRT *transp;
};
extern bool_t xdr_intpair();
#define NTHREADS_CONST 500
Example 4-42 is the client for MT User mode.
Example 4-42 Client for MT User Mode
#define _REENTRANT
#include <stdio.h>
#include <rpc/rpc.h>
#include <sys/uio.h>
#include <netconfig.h>
#include <netdb.h>
#include <rpc/nettype.h>
#include <thread.h>
#include "rpc_test.h"
void *doclient();
int NTHREADS;
struct thread_info {
thread_t client_id;
int client_status;
};
struct thread_info save_thread[NTHREADS_CONST];
main(argc, argv)
int argc;
char *argv[];
{
int index, ret;
int thread_status;
thread_t departedid, client_id;
char *hosts;
if (argc < 3) {
printf("Usage: do_operation [n] host\n");
printf("\twhere n is the number of threads\n");
exit(1);
} else
if (argc == 3) {
NTHREADS = NTHREADS_CONST;
hosts = argv[1]; /* live_host */
} else {
NTHREADS = atoi(argv[1]);
hosts = argv[2];
}
for (index = 0; index < NTHREADS; index++){
if (ret = thr_create(NULL, NULL, doclient,
(void *) hosts, THR_BOUND, &client_id)){
printf("thr_create failed: return value %d", ret);
printf(" for %dth thread\n", index);
exit(1);
}
save_thread[index].client_id = client_id;
}
for (index = 0; index < NTHREADS; index++){
if (thr_join(save_thread[index].client_id, &departedid,
(void *)
&thread_status)){
printf("thr_join failed for thread %d\n",
save_thread[index].client_id);
exit(1);
}
save_thread[index].client_status = thread_status;
}
}
void *doclient(host)
char *host;
{
struct timeval tout;
enum clnt_stat test;
int result = 0;
u_short mult_result = 0;
int add_arg;
int EXP_RSLT;
intpair pair;
CLIENT *clnt;
if ((clnt = clnt_create(host, SVC2_PROG, SVC2_VERS, "udp"
==NULL) {
clnt_pcreateerror("clnt_create error: ");
thr_exit((void *) -1);
}
tout.tv_sec = 25;
tout.tv_usec = 0;
memset((char *) &result, 0, sizeof (result));
memset((char *) &mult_result, 0, sizeof (mult_result));
if (thr_self() % 2){
EXP_RSLT = thr_self() + 1;
add_arg = thr_self();
test = clnt_call(clnt, SVC2_PROC_ADD, (xdrproc_t) xdr_int,
(caddr_t) &add_arg, (xdrproc_t) xdr_int, (caddr_t) &result,
tout);
} else {
pair.a = (u_short) thr_self();
pair.b = (u_short) 1;
EXP_RSLT = pair.a * pair.b;
test = clnt_call(clnt, SVC2_PROC_MULT, (xdrproc_t)
xdr_intpair,
(caddr_t) &pair, (xdrproc_t) xdr_u_short,
(caddr_t) &mult_result, tout);
result = mult_result;
}
if (test != RPC_SUCCESS) {
printf("THREAD: %d clnt_call hav
thr_exit((void *) -1);
};
thr_exit((void *) 0);
}
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Example 4-43 shows the server side in MT User mode. MT performance is enhanced if the function svc_getargs() is called by every procedure other than NULLPROC, even if there are no arguments (xdr_void may be used in this case). This is true for both the MT Auto and MT User modes. For more information on this call, see the rpc_svc_calls(3NSL) man page.
Note -
You must link in the thread library when writing RPC multithreaded-safe applications. The thread library must be the last named library on the link line. To do this, specify the -lthread option in the compile command.
Example 4-43 Server for MT User Mode
#define _REENTRANT
#include <stdio.h>
#include <rpc/rpc.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/uio.h>
#include <signal.h>
#include <thread.h>
#include "operations.h"
SVCXPRT *xprt;
void add_mult_prog();
void *svc2_add_worker();
void *svc2_mult_worker();
main(argc, argv)
int argc;
char **argv;
{
int transpnum;
char *nettype;
int mode = RPC_SVC_MT_USER;
if(rpc_control(RPC_SVC_MTMODE_SET,&mode) == FALSE){
printf(" rpc_control is failed to set AUTO mode\n");
exit(0);
}
if (argc > 2) {
fprintf(stderr, "usage: %s [nettype]\n", argv[0]);
exit(1);
}
if (argc == 2)
nettype = argv[1];
else
nettype = "netpath";
transpnum = svc_create(add_mult_prog, SVC2_PROG,
SVC2_VERS, nettype);
if (transpnum == 0) {
fprintf(stderr, "%s: cannot create %s service.\n", argv[0],
nettype);
exit(1);
}
svc_run();
}
void add_mult_prog (rqstp, transp)
struct svc_req *rqstp;
SVCXPRT *transp;
{
int argument;
u_short mult_arg();
intpair mult_argument;
bool_t (*xdr_argument)();
struct svc2_mult_args *sw_mult_data;
struct svc2_add_args *sw_add_data;
int ret;
thread_t worker_id;
switch (rqstp->rq_proc){
case NULLPROC:
svc_sendreply(transp, xdr_void, (char *) 0);
svc_done(transp);
break;
case SVC2_PROC_ADD:
xdr_argument = xdr_int;
(void) memset((char *) &argument, 0, sizeof (argument));
if (!svc_getargs(transp, xdr_argument,
(char *) &argument)){
printf("problem with getargs\n");
svcerr_decode(transp);
exit(1);
}
sw_add_data = (struct svc2_add_args *)
malloc(sizeof (struct svc2_add_args));
sw_add_data->transp = transp;
sw_add_data->argument = argument;
if (ret = thr_create(NULL, THR_MIN_STACK + 16 * 1024,
svc2_add_worker, (void *) sw_add_data, THR_DETACHED,
printf("SERVER: thr_create failed:");
printf(" return value %d", ret);
printf(" for add thread\n");
exit(1);
}
break;
case SVC2_PROC_MULT:
xdr_argument = xdr_intpair;
(void) memset((char *) &mult_argument, 0,
sizeof (mult_argument));
if (!svc_getargs(transp, xdr_argument,
(char *) &mult_argument)){
printf("problem with getargs\n");
svcerr_decode(transp);
exit(1);
}
sw_mult_data = (struct svc2_mult_args *)
malloc(sizeof (struct svc2_mult_args));
sw_mult_data->transp = transp;
sw_mult_data->mult_argument.a = mult_argument.a;
sw_mult_data->mult_argument.b = mult_argument.b;
if (ret = thr_create(NULL, THR_MIN_STACK + 16 * 1024,
svc2_mult_worker, (void *) sw_mult_data, THR_DETACHED,
&worker_id)){
printf("SERVER: thr_create failed:");
printf("return value %d", ret);
printf("for multiply thread\n");
exit(1);
break;
default:
svcerr_noproc(transp);
svc_done(transp);
break;
}
}
u_short mult_arg();
int add_one();
void *svc2_add_worker(add_arg)
struct svc2_add_args *add_arg;
{ int *result;
bool_t (*xdr_result)();
xdr_result = xdr_int;
result = *malloc(sizeof (int));
*result = add_one(add_arg->argument);
if (!svc_sendreply(add_arg->transp, xdr_result,
(caddr_t) result)){
printf("sendreply failed\n");
svcerr_systemerr(add_arg->transp);
svc_done(add_arg->transp);
thr_exit((void *) -1);
}
svc_done(add_arg->transp);
thr_exit((void *) 0);
}
void *svc2_mult_worker(m_arg)
struct svc2_mult_args *m_arg;
{
u_short *result;
bool_t (*xdr_result)();
xdr_result = xdr_u_short;
result = (u_short *) malloc(sizeof (u_short));
*result = mult_arg(&m_arg->mult_argument);
if (!svc_sendreply(m_arg->transp, xdr_result,
(caddr_t) result)){
printf("sendreply failed\n");
svcerr_systemerr(m_arg->transp);
svc_done(m_arg->transp);
thr_exit((void *) -1);
}
svc_done(m_arg->transp);
thr_exit((void *) 0);
}
u_short mult_arg(pair)
intpair *pair;
{
u_short result;
result = pair->a * pair->b;
return (result);}
int add_one(arg)
int arg;
{
return (++arg);
}
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