Using a simple counter with non-blocking I/O

The client.c file in the one-way messaging example is modified in this section to demonstrate how to use the non-blocking I/O mode. In this new file, client_nonblo.c, the I/O mode is specified as non-blocking with the RPC_CL_NONBLOCKING argument, the flush mode is chosen to be blocking by use of the RPC_CL_BLOCKING_FLUSH. The I/O mode and flush mode are invoked with CLSET_IO_MODE. When an error occurs RPC_CANT_STORE is returned to the client and the program tries to flush the buffer. To choose a different method of flush consult the clnt_control(3NSL) man page.

#include <stdio.h>
#include "counter.h"

main(int argc, char *argv[])
{
    CLIENT* clnt;
    enum clnt_stat result;
    char *server;
    int number;
    bool_t bres;
		/* 
		 * Choose the I/O mode and flush method to be used.
		 * The non-blocking I/O mode and blocking flush are 
		 * chosen in this example.
		 */
    int mode = RPC_CL_NONBLOCKING;
    int flushMode = RPC_CL_BLOCKING_FLUSH;

    if (argc != 3) {
			  fprintf(stderr, "usage: %s server_name number\n", argv[0]);
			  exit(1);
    }
    server = argv[1];
    number = atoi(argv[2]);

    clnt= clnt_create(server, COUNTERPROG, COUNTERVERS, "tcp");
    if (clnt == (CLIENT*) NULL) {
			  clnt_pcreateerror(server);
			  exit(1);
    }

		/* 
 	 * Use clnt_control to set the I/O mode. 
 	 * The non-blocking I/O mode is 
 	 * chosen for this example.
 	 */
    bres = clnt_control(clnt, CLSET_IO_MODE, (char*)&mode);
    if (bres)
	    /* 
		  * Set flush mode to blocking 
		  */
        bres = clnt_control(clnt, CLSET_FLUSH_MODE, (char*)&flushMode);

    if (!bres) {
        clnt_perror(clnt, "clnt_control");
        exit(1);
    }
		 /* 
 	  * Call the RPC services.
 	  */
    result = add_1(number, clnt);

    switch (result) {
    case RPC_SUCCESS:
        fprintf(stdout,"Success\n");
        break;
		/*
 	 * RPC_CANTSTORE is a new value returned to the 
		 * client when the buffer cannot store a request.
		 */
    case RPC_CANTSTORE:
        fprintf(stdout,"RPC_CANTSTORE error. Flushing ... \n");
		/*
		 * The buffer is flushed using the blocking flush method
		 */
			  bres = clnt_control(clnt, CLFLUSH, NULL);
        if (!bres) {
	    		   clnt_perror(clnt, "clnt_control");
			  }
        break;
    default:
			  clnt_perror(clnt, "call failed");
        break;
    }

    /* Flush */
    bres = clnt_control(clnt, CLFLUSH, NULL);
    if (!bres) {
			  clnt_perror(clnt, "clnt_control");
    }

    clnt_destroy(clnt);
    exit(0);
}