12 # If we don't say anything, maybe nobody will notice.
13 # print STDERR "\nWarning: I'm testing the speedup. This might take up to thirty seconds.\n ";
17 sub times_to_time { my ($u) = times; $u; }
18 if ($^O eq 'riscos') {
19 eval {require Time::HiRes; *my_time = \&Time::HiRes::time };
20 if ($@) { *my_time = sub { time }; $COARSE_TIME = 1 }
22 *my_time = \×_to_time;
30 # This next test finds an example that takes a long time to run, then
31 # checks to make sure that the run is actually speeded up by memoization.
32 # In some sense, this is the most essential correctness test in the package.
34 # We do this by running the fib() function with successfily larger
35 # arguments until we find one that tales at least $LONG_RUN seconds
36 # to execute. Then we memoize fib() and run the same call cagain. If
37 # it doesn't produce the same test in less than one-tenth the time,
38 # something is seriously wrong.
40 # $LONG_RUN is the number of seconds that the function call must last
41 # in order for the call to be considered sufficiently long.
48 fib($n-1) + fib($n-2);
51 sub max { $_[0] > $_[1] ?
65 $ELAPSED = time - $start;
66 last if $ELAPSED >= $LONG_RUN;
68 print "# fib($N) took $ELAPSED seconds.\n" if $N % 1 == 0;
69 # we'd expect that fib(n+1) takes about 1.618 times as long as fib(n)
70 # so now that we have a longish run, let's estimate the value of $N
71 # that will get us a sufficiently long run.
72 $N += 1 + int(log($LONG_RUN/$ELAPSED)/log(1.618));
73 print "# OK, N=$N ought to do it.\n";
74 # It's important not to overshoot here because the running time
75 # is exponential in $N. If we increase $N too aggressively,
76 # the user will be forced to wait a very long time.
82 print "# OK, fib($N) was slow enough; it took $ELAPSED seconds.\n";
83 print "# Total calls: $COUNT.\n";
90 $ELAPSED2 = time - $start + .001; # prevent division by 0 errors
92 print (($RESULT == $RESULT2) ? "ok 1\n" : "not ok 1\n");
93 # If it's not ten times as fast, something is seriously wrong.
94 print (($ELAPSED/$ELAPSED2 > 10) ? "ok 2\n" : "not ok 2\n");
95 # If it called the function more than $N times, it wasn't memoized properly
96 print (($COUNT > $N) ? "ok 3\n" : "not ok 3\n");
98 # Do it again. Should be even faster this time.
102 $ELAPSED2 = time - $start + .001; # prevent division by 0 errors
104 print (($RESULT == $RESULT2) ? "ok 4\n" : "not ok 4\n");
105 print (($ELAPSED/$ELAPSED2 > 10) ? "ok 5\n" : "not ok 5\n");
106 # This time it shouldn't have called the function at all.
107 print ($COUNT == 0 ? "ok 6\n" : "not ok 6\n");