Rendezvous: Difference between revisions

}</lang>

=={{header|C}}==

Basically just synched threads doing printing: since task didn't ask for service type or resource enumeration, and "message passing is stupid" (c.f. talk), the guarding thread is no more than a glorified mutex, hence completely cut out, leaving the threads directly check ink and do print.

<lang C>#include <stdio.h>

#include <unistd.h>

#include <omp.h>

typedef struct printer printer;

struct printer { int id, ink; };

printer pnt_main = { 1, 5 };

printer pnt_backup = { 2, 5 };

int print(char * text, char **error)

{

#pragma omp critical

{

printer *p = &pnt_main;

if (!p->ink) p = &pnt_backup;

if (!p->ink)

*error = "Out of ink";

else {

*error = 0;

p->ink--;

printf("%d | ", p->id, p->ink);

while (*text != '\0') {

putchar(*(text++));

fflush(stdout);

usleep(30000);

}

putchar('\n');

}

}

return 0 != *error;

}

char *humpty[] = {

"Humpty Dumpty sat on a wall.",

"Humpty Dumpty had a great fall.",

"All the king's horses and all the king's men,",

"Couldn't put Humpty together again."

};

char *goose[] = {

"Old Mother Goose,",

"When she wanted to wander,",

"Would ride through the air,",

"On a very fine gander.",

"Jack's mother came in,",

"And caught the goose soon,",

"And mounting its back,",

"Flew up to the moon."

};

int main()

{

int i, j, len;

char *msg, **text;

omp_set_num_threads(2);

#pragma omp parallel for private(text, msg, len, j)

for (i = 0; i < 2; i++) {

text = i ? goose : humpty;

len = (i ? sizeof(goose) : sizeof(humpty) ) / sizeof(char*);

for (j = 0; j < len; j++) {

usleep(100000);

if (print(text[j], &msg)) {

fprintf(stderr, "Error: %s\n", msg);

break;

}

}

}

return 0;