/*
 * This file is part of Jehanne.
 *
 * Copyright (C) 2015 Giacomo Tesio <giacomo@tesio.it>
 *
 * Jehanne is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2 of the License.
 *
 * Jehanne is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Jehanne.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <u.h>
#include <lib9.h>

/* verify that rlockt returns 1 if the lock is released and
 * it can take it
 */

#define NPROC 50
RWLock afterAWhile;	/* held for a while by main, then readers will take it */

int killerProc;	/* pid, will kill the other processes if starved */

int elapsed[NPROC];
int32_t completed;
QLock rl;
Rendez rStart;
Rendez rCompleted;

int verbose = 0;

void
killKiller(void)
{
	postnote(PNPROC, killerProc, "interrupt");
}

void
stopAllAfter(int seconds)
{
	int pid;

	switch((pid = sys_rfork(RFMEM|RFPROC|RFNOWAIT)))
	{
		case 0:
			if(verbose)
				print("killer proc started: pid %d\n", getpid());
			sleep(seconds * 1000);
			postnote(PNGROUP, killerProc, "timedout");
			if(verbose)
				print("killer proc timedout: pid %d\n", getpid());
			exits("FAIL");
		case -1:
			fprint(2, "stopAllAfter: %r\n");
			exits("sys_rfork fails");
		default:
			if(verbose)
				print("killer proc spawn: pid %d\n", pid);
			killerProc = pid;
			atexit(killKiller);
	}
}

int
handletimeout(void *v, char *s)
{
	if(strcmp(s, "timedout") == 0){
		if(verbose)
			print("%d: noted: %s\n", getpid(), s);
		print("FAIL: %s timedout\n", argv0);
		exits("FAIL");
	}
	return 0;
}

int
handlefail(void *v, char *s)
{
	if(strncmp(s, "fail", 4) == 0){
		if(verbose)
			print("%d: noted: %s\n", getpid(), s);
		print("FAIL: %s\n", s);
		exits("FAIL");
	}
	return 0;
}

char *
waiter(int index)
{
	int64_t start, end;

	/* wait for the afterAWhile to be locked by the main process */
	qlock(&rl);
	while(afterAWhile.writer == 0)
		rsleep(&rStart);
	qunlock(&rl);

	/* try to lock for ~1000 s, but it will be available after ~1s */
	start = nsec();
	end = start;
	if(verbose)
		print("reader %d: started\n", getpid());
	if(rlockt(&afterAWhile, 100000)){
		end = nsec();
		if(verbose)
			print("reader %d: got the rlock in %lld ms\n", getpid(), (end - start) / (1000*1000));
		runlock(&afterAWhile);
		if((end - start) / (1000*1000) > 2000)
			postnote(PNGROUP, getpid(), smprint("fail: reader %d got the rlock after %lld ms", getpid(),  (end - start) / (1000*1000)));
	} else {
		if(verbose)
			print("reader %d failed: rlockt timedout in %lld ms\n", getpid(), (nsec() - start) / (1000*1000));
		postnote(PNGROUP, getpid(), smprint("fail: reader %d timedout", getpid()));
	}

	/* notify the main process that we have completed */
	qlock(&rl);
	elapsed[index] = end - start;
	++completed;
	rwakeup(&rCompleted);
	qunlock(&rl);

	return (end - start) / (1000*1000) < 2000 ? nil : "FAIL";
}

void
spawnWaiter(int index)
{
	int pid;
	char * res;

	switch((pid = sys_rfork(RFMEM|RFPROC|RFNOWAIT)))
	{
		case 0:
			res = waiter(index);
			exits(res);
			break;
		case -1:
			print("spawnWaiter: %r\n");
			exits("sys_rfork fails");
			break;
		default:
			if(verbose)
				print("spawn reader %d\n", pid);
			break;
	}
}

void
main(int argc, char* argv[])
{
	int i;
	int64_t average, end;

	ARGBEGIN{
	}ARGEND;

	sys_rfork(RFNOTEG|RFREND);
	rStart.l = &rl;
	rCompleted.l = &rl;

	if(verbose)
		print("main: started with pid %d\n", getpid());

	for(i = 0; i < NPROC; ++i){
		spawnWaiter(i);
	}

	if (!atnotify(handletimeout, 1)){
		fprint(2, "atnotify(handletimeout): %r\n");
		exits("atnotify fails");
	}
	if (!atnotify(handlefail, 1)){
		fprint(2, "atnotify(handlefail): %r\n");
		exits("atnotify fails");
	}

	stopAllAfter(60);	/* ensure we exit */

	qlock(&rl);
	wlock(&afterAWhile);
	if(verbose)
		print("main: got the afterAWhile: wakeup all readers...\n");
	rwakeupall(&rStart);
	if(verbose)
		print("main: got the afterAWhile: wakeup all readers... done\n");
	end = nsec() + 1000*1000*1000;
	qunlock(&rl);

	/* wait for ~1 sec */
	do { sleep(100); } while(nsec() < end);

	wunlock(&afterAWhile);

	if(verbose)
		print("main: released the afterAWhile\n");

	qlock(&rl);
	if(verbose)
		print("main: waiting all readers to take the lock...\n");
	while(completed < NPROC){
		rsleep(&rCompleted);
		if(verbose && completed < NPROC)
			print("main: awaked, but %d readers are still pending\n", NPROC - completed);
	}
	qunlock(&rl);
	if(verbose)
		print("main: waiting all readers to take the lock... done\n");

	average = 0;
	for(i = 0; i < NPROC; ++i){
		average += elapsed[i];
	}
	average = average / NPROC / (1000 * 1000);

	if(average > 900 && average < 5000)
	{
		print("PASS\n");
		exits("PASS");
	}
	print("FAIL: %s: average timeout too long %lld ms\n", argv0, average);
	exits("FAIL");
}