hires.t

source of perl for linux application,

    while (getitimer(&ITIMER_VIRTUAL)) {
	my $j;
	for (1..1000) { $j++ } # Can't be unbreakable, must test getitimer().
    }

    print "# getitimer: ", join(" ", getitimer(ITIMER_VIRTUAL)), "\n";

    $virt = getitimer(&ITIMER_VIRTUAL);
    print "not " unless defined $virt && $virt == 0;
    print "ok 19\n";

    $SIG{VTALRM} = 'DEFAULT';
}

if ($have_gettimeofday &&
    $have_usleep) {
    use Time::HiRes qw(usleep);

    my ($t0, $td);

    my $sleep = 1.5; # seconds
    my $msg;

    $t0 = gettimeofday();
    $a = abs(sleep($sleep)        / $sleep         - 1.0);
    $td = gettimeofday() - $t0;
    my $ratio = 1.0 + $a;

    $msg = "$td went by while sleeping $sleep, ratio $ratio.\n";

    if ($td < $sleep * (1 + $limit)) {
	print $a < $limit ? "ok 20 # $msg" : "not ok 20 # $msg";
    } else {
	print "ok 20 # Skip: $msg";
    }

    $t0 = gettimeofday();
    $a = abs(usleep($sleep * 1E6) / ($sleep * 1E6) - 1.0);
    $td = gettimeofday() - $t0;
    $ratio = 1.0 + $a;

    $msg = "$td went by while sleeping $sleep, ratio $ratio.\n";

    if ($td < $sleep * (1 + $limit)) {
	print $a < $limit ? "ok 21 # $msg" : "not ok 21 # $msg";
    } else {
	print "ok 21 # Skip: $msg";
    }

} else {
    for (20..21) {
	print "ok $_ # Skip: no gettimeofday\n";
    }
}

unless ($have_nanosleep) {
    skip 22..23;
}
else {
    my $one = CORE::time;
    nanosleep(10_000_000);
    my $two = CORE::time;
    nanosleep(10_000_000);
    my $three = CORE::time;
    ok 22, $one == $two || $two == $three, "slept too long, $one $two $three";

    unless ($have_gettimeofday) {
    	skip 23;
    }
    else {
    	my $f = Time::HiRes::time();
	nanosleep(500_000_000);
        my $f2 = Time::HiRes::time();
	my $d = $f2 - $f;
	ok 23, $d > 0.4 && $d < 0.9, "slept $d secs $f to $f2";
    }
}

eval { sleep(-1) };
print $@ =~ /::sleep\(-1\): negative time not invented yet/ ?
    "ok 24\n" : "not ok 24\n";

eval { usleep(-2) };
print $@ =~ /::usleep\(-2\): negative time not invented yet/ ?
    "ok 25\n" : "not ok 25\n";

if ($have_ualarm) {
    eval { alarm(-3) };
    print $@ =~ /::alarm\(-3, 0\): negative time not invented yet/ ?
	"ok 26\n" : "not ok 26\n";

    eval { ualarm(-4) };
    print $@ =~ /::ualarm\(-4, 0\): negative time not invented yet/ ?
    "ok 27\n" : "not ok 27\n";
} else {
    skip 26;
    skip 27;
}

if ($have_nanosleep) {
    eval { nanosleep(-5) };
    print $@ =~ /::nanosleep\(-5\): negative time not invented yet/ ?
	"ok 28\n" : "not ok 28\n";
} else {
    skip 28;
}

# Find the loop size N (a for() loop 0..N-1)
# that will take more than T seconds.

if ($have_ualarm && $] >= 5.008001) {
    # http://groups.google.com/group/perl.perl5.porters/browse_thread/thread/adaffaaf939b042e/20dafc298df737f0%2320dafc298df737f0?sa=X&oi=groupsr&start=0&num=3
    # Perl changes [18765] and [18770], perl bug [perl #20920]

    print "# Finding delay loop...\n";

    my $T = 0.01;
    use Time::HiRes qw(time);
    my $DelayN = 1024;
    my $i;
 N: {
     do {
	 my $t0 = time();
	 for ($i = 0; $i < $DelayN; $i++) { }
	 my $t1 = time();
	 my $dt = $t1 - $t0;
	 print "# N = $DelayN, t1 = $t1, t0 = $t0, dt = $dt\n";
	 last N if $dt > $T;
	 $DelayN *= 2;
     } while (1);
 }

    # The time-burner which takes at least T (default 1) seconds.
    my $Delay = sub {
	my $c = @_ ? shift : 1;
	my $n = $c * $DelayN;
	my $i;
	for ($i = 0; $i < $n; $i++) { }
    };

    # Next setup a periodic timer (the two-argument alarm() of
    # Time::HiRes, behind the curtains the libc ualarm()) which has
    # a signal handler that takes so much time (on the first initial
    # invocation) that the first periodic invocation (second invocation)
    # will happen before the first invocation has finished.  In Perl 5.8.0
    # the "safe signals" concept was implemented, with unfortunately at least
    # one bug that caused a core dump on reentering the handler. This bug
    # was fixed by the time of Perl 5.8.1.

    # Do not try mixing sleep() and alarm() for testing this.

    my $a = 0; # Number of alarms we receive.
    my $A = 2; # Number of alarms we will handle before disarming.
               # (We may well get $A + 1 alarms.)

    $SIG{ALRM} = sub {
	$a++;
	print "# Alarm $a - ", time(), "\n";
	alarm(0) if $a >= $A; # Disarm the alarm.
	$Delay->(2); # Try burning CPU at least for 2T seconds.
    }; 

    use Time::HiRes qw(alarm); 
    alarm($T, $T);  # Arm the alarm.

    $Delay->(10); # Try burning CPU at least for 10T seconds.

    print "ok 29\n"; # Not core dumping by now is considered to be the success.
} else {
    skip 29;
}

if ($have_clock_gettime &&
    # All implementations of clock_gettime() 
    # are SUPPOSED TO support CLOCK_REALTIME.
    has_symbol('CLOCK_REALTIME')) {
    my $ok = 0;
 TRY: {
	for my $try (1..3) {
	    print "# CLOCK_REALTIME: try = $try\n";
	    my $t0 = clock_gettime(&CLOCK_REALTIME);
	    use Time::HiRes qw(sleep);
	    my $T = 1.5;
	    sleep($T);
	    my $t1 = clock_gettime(&CLOCK_REALTIME);
	    if ($t0 > 0 && $t1 > $t0) {
		print "# t1 = $t1, t0 = $t0\n";
		my $dt = $t1 - $t0;
		my $rt = abs(1 - $dt / $T);
		print "# dt = $dt, rt = $rt\n";
		if ($rt <= 2 * $limit) {
		    $ok = 1;
		    last TRY;
		}
	    } else {
		print "# Error: t0 = $t0, t1 = $t1\n";
	    }
	    my $r = rand() + rand();
	    printf "# Sleeping for %.6f seconds...\n", $r;
	    sleep($r);
	}
    }
    if ($ok) {
	print "ok 30\n";
    } else {
	print "not ok 30\n";
    }
} else {
    print "# No clock_gettime\n";
    skip 30;
}

if ($have_clock_getres) {
    my $tr = clock_getres();
    if ($tr > 0) {
	print "ok 31 # tr = $tr\n";
    } else {
	print "not ok 31 # tr = $tr\n";
    }
} else {
    print "# No clock_getres\n";
    skip 31;
}

if ($have_clock_nanosleep &&
    has_symbol('CLOCK_REALTIME')) {
    my $s = 1.5e9;
    my $t = clock_nanosleep(&CLOCK_REALTIME, $s);
    my $r = abs(1 - $t / $s);
    if ($r < 2 * $limit) {
	print "ok 32\n";
    } else {
	print "not ok 32 # $t = $t, r = $r\n";
    }
} else {
    print "# No clock_nanosleep\n";
    skip 32;
}

if ($have_clock) {
    my @clock = clock();
    print "# clock = @clock\n";
    for my $i (1..3) {
	for (my $j = 0; $j < 1e6; $j++) { }
	push @clock, clock();
	print "# clock = @clock\n";
    }
    if ($clock[0] >= 0 &&
	$clock[1] > $clock[0] &&
	$clock[2] > $clock[1] &&
	$clock[3] > $clock[2]) {
	print "ok 33\n";
    } else {
	print "not ok 33\n";
    }
} else {
    skip 33;
}

if ($have_ualarm) {
    # 1_100_000 sligthly over 1_000_000,
    # 2_200_000 slightly over 2**31/1000,
    # 4_300_000 slightly over 2**32/1000.
    for my $t ([34, 100_000],
	       [35, 1_100_000],
	       [36, 2_200_000],
	       [37, 4_300_000]) {
	my ($i, $n) = @$t;
	my $alarmed = 0;
	local $SIG{ ALRM } = sub { $alarmed++ };
	my $t0 = Time::HiRes::time();
	print "# t0 = $t0\n";
	print "# ualarm($n)\n";
	ualarm($n); 1 while $alarmed == 0;
	my $t1 = Time::HiRes::time();
	print "# t1 = $t1\n";
	my $dt = $t1 - $t0;
	print "# dt = $dt\n";
	my $r = $dt / ($n/1e6);
	print "# r = $r\n";
	ok $i,
	($n < 1_000_000 || # Too much noise.
	 $r >= 0.8 && $r <= 1.6), "ualarm($n) close enough";
    }
} else {
    print "# No ualarm\n";
    skip 34..37;
}

if ($^O =~ /^(cygwin|MSWin)/) {
    print "# $^O: timestamps may not be good enough\n";
    skip 38;
} elsif (&Time::HiRes::d_hires_stat) {
    my @stat;
    my @atime;
    my @mtime;
    for (1..5) {
	Time::HiRes::sleep(rand(0.1) + 0.1);
	open(X, ">$$");
	print X $$;
	close(X);
	@stat = Time::HiRes::stat($$);
	push @mtime, $stat[9];
	Time::HiRes::sleep(rand(0.1) + 0.1);
	open(X, "<$$");
	<X>;
	close(X);
	@stat = Time::HiRes::stat($$);
	push @atime, $stat[8];
    }
    1 while unlink $$;
    print "# mtime = @mtime\n";
    print "# atime = @atime\n";
    my $ai = 0;
    my $mi = 0;
    my $ss = 0;
    for (my $i = 1; $i < @atime; $i++) {
	if ($atime[$i] >= $atime[$i-1]) {
	    $ai++;
	}
	if ($atime[$i] > int($atime[$i])) {
	    $ss++;
	}
    }
    for (my $i = 1; $i < @mtime; $i++) {
	if ($mtime[$i] >= $mtime[$i-1]) {
	    $mi++;
	}
	if ($mtime[$i] > int($mtime[$i])) {
	    $ss++;
	}
    }
    print "# ai = $ai, mi = $mi, ss = $ss\n";
    # Need at least 75% of monotonical increase and
    # 20% of subsecond results. Yes, this is guessing.
    if ($ss == 0) {
	print "# No subsecond timestamps detected\n";
	skip 38;
    } elsif ($mi/(@mtime-1) >= 0.75 && $ai/(@atime-1) >= 0.75 &&
	     $ss/(@mtime+@atime) >= 0.2) {
	print "ok 38\n";
    } else {
	print "not ok 38\n";
    }
} else {
    print "# No effectual d_hires_stat\n";
    skip 38;
}

END {
    if ($timer_pid) { # Only in the main process.
	my $left = $TheEnd - time();
	printf "# I am the main process $$, terminating the timer process $timer_pid\n# before it terminates me in %d seconds (testing took %d seconds).\n", $left, $waitfor - $left;
	my $kill = kill('TERM', $timer_pid); # We are done, the timer can go.
	printf "# kill TERM $timer_pid = %d\n", $kill;
	unlink("ktrace.out"); # Used in BSD system call tracing.
	print "# All done.\n";
    }
}