harvey/sys/src/regress/pipering.c

#include <u.h>
#include <libc.h>

int nring = 32;
int niter = 65536;
int debug = 0;
char data[8192];
int i;
int id;
int intr = 0;

void
handler(void *v, char *s)
{
	print("%d: %d iterations\n", id, i);
	if (intr++ < 16)
		noted(NCONT);
	exits("too many interrupts");
}

void
main(int argc, char *argv[])
{
	int pid;

	if (notify(handler)){
		sysfatal("notify: %r");
	}

	if (argc > 1)
		nring = strtoull(argv[1], 0, 0);

	if (argc > 2)
		niter = strtoull(argv[2], 0, 0);
	debug = argc > 3;

	print("Running with %d pipes %d times\n", nring, niter);
	int *pfd = malloc(sizeof(*pipe)* nring * 2);

	if (pfd == nil)
		sysfatal(smprint("alloc %d pipes: %r", nring*2));

	for(i = 0; i < nring; i++)
		if (pipe(&pfd[i*2]) < 0)
			sysfatal(smprint("create pipe pair %d of %d: %r", i, nring));

	for(i = 0; debug && i < nring; i++ ) print("pfd[%d,%d]\n", pfd[i*2],pfd[i*2+1]);
	for(i = 0, id = 0; i < nring-1; i++, id++) {
		pid = fork();
		if (pid == 0)
			break;
		if (pid < 0)
			sysfatal("fork");
	}

	if (debug) print("Forked. pid %d\n", getpid());
	for(i = 0; debug && i < nring; i++ ) print("pfd[%d,%d]\n", pfd[i*2],pfd[i*2+1]);
	for(i = 0; i < niter; i++) {
		if (debug) print("%d: write %d\n", id, pfd[(id%nring)*2+1]);
		int amt = write(pfd[(id%nring)*2+1], data, sizeof(data));
		if (amt < sizeof(data))
			sysfatal(smprint("%d: write only got %d of %d: %r", id, amt, sizeof(data)));
		if (debug) print("%d: read %d\n", id, pfd[(id%nring)*2]);
		amt = read(pfd[(id%nring)*2], data, sizeof(data));
		if (amt < sizeof(data))
			sysfatal(smprint("%d: read only got %d of %d: %r", id, amt, sizeof(data)));
	}
}