Example concurrent network requests using the Plan 9 threads library

concio_ex.c

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

int STKSIZE = 2*1024;

struct SleepArgs {
	long millies;
	Channel *c;
};
typedef struct SleepArgs SleepArgs;

void
sleeper(void *arg)
{
	SleepArgs *sa = arg;

	Ioproc *io = ioproc();
	iosleep(io, sa->millies);
	closeioproc(io);

	send(sa->c, 0);
}

struct WorkArgs {
	char *addr;
	char *msg;
	int mlen;
	Channel *c;
};
typedef struct WorkArgs WorkArgs;

void
worker(void *arg)
{
	WorkArgs *wa = arg;
	char ret[128];
	Ioproc *io = ioproc();
	int fd = iodial(io, wa->addr, nil, nil, nil);
	int hit = 0;

	if(fd >= 0) {
		if(iowrite(io, fd, wa->msg, wa->mlen) >= 0) {
			if (ioread(io, fd, ret, sizeof(ret)) >= 0) {
				hit = 1;
			}
		}
	}

	closeioproc(io);
	sendul(wa->c, hit);
}

struct DispatchArgs {
	long timeout;
	char *addr;
	char *data;
	int dlen;
};
typedef struct DispatchArgs DispatchArgs;

void
dispatcher(void *arg)
{
	enum { Sleeper, Worker };
	DispatchArgs *da = arg;
	int st;

	Alt a[] = {
		{nil, nil, CHANRCV},
		{nil, &st, CHANRCV},
		{nil, nil, CHANEND},
	};

	a[Sleeper].c = chancreate(sizeof(int), 0);
	a[Worker].c = chancreate(sizeof(int), 0);

	SleepArgs sa = {da->timeout, a[Sleeper].c};
	threadcreate(sleeper, &sa, STKSIZE);

	WorkArgs wa = {da->addr, da->data, da->dlen, a[Worker].c};
	threadcreate(worker, &wa, STKSIZE);

	switch(alt(a)){
	case Sleeper:
		print("time out\n");
		break;
	case Worker:
		if (st) {
			print("success\n");
		} else {
			print("failure\n");
		}
		break;
	default:
		sysfatal("can't happen");
	}
}

/*
 Examples:
	./concio_ex -a 'tcp!bootes!echo' -t 1 -n 10

	./concio_ex -a 'tcp!52.43.121.77!9001' -t 1 -n 42 | grep success | wc -l

	./concio_ex -a 'udp!52.43.121.77!10001' -t 3 -n 63 | grep success | wc -l

*/
void
threadmain(int argc, char *argv[])
{
	int nprocs = 80;	// number of concurrent workers
	char *addr = "udp!52.43.121.77!10001";	// hosted by digi.com
	long tout = 1000;	// default timeout 1s
	char * f;

	ARGBEGIN {
	case 'n':
		f = ARGF();
		if (f) nprocs = atoi(f);
		break;
	case 'a':
		f = ARGF();
		if (f) addr = f;
		break;
	case 't':
		f = ARGF();
		if (f) tout = atol(f) * 1000;
		break;
	default:
		print("badflag('%c')", ARGC());
		exits("flag");
	} 
	ARGEND

	DispatchArgs da = {tout,addr, "Echo this back", sizeof("Echo this back")};
	for(int i = 0; i < nprocs; i++){
		proccreate(dispatcher, &da, STKSIZE);
	}

	sleep(tout);

	threadexitsall(0);
}