18 # If we don't say anything, maybe nobody will notice.
19 # print STDERR "\nWarning: I'm testing the speedup. This might take up to thirty seconds.\n ";
21 sub times_to_time { my ($u) = times; $u; }
22 if ($^O eq 'riscos') {
23 eval {require Time::HiRes; *my_time = \&Time::HiRes::time };
24 if ($@) { *my_time = sub { time }; }
26 *my_time = \×_to_time;
34 # This next test finds an example that takes a long time to run, then
35 # checks to make sure that the run is actually speeded up by memoization.
36 # In some sense, this is the most essential correctness test in the package.
38 # We do this by running the fib() function with successively larger
39 # arguments until we find one that takes at least $LONG_RUN seconds
40 # to execute. Then we memoize fib() and run the same call cagain. If
41 # it doesn't produce the same test in less than one-tenth the time,
42 # something is seriously wrong.
44 # $LONG_RUN is the number of seconds that the function call must last
45 # in order for the call to be considered sufficiently long.
52 fib($n-1) + fib($n-2);
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";
89 our $RESULT2 = fib($N);
90 our $ELAPSED2 = (time - $start) || 1; # prevent division by 0 errors
92 print (($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/$ELAPSED2 >= 10) ? "ok 2 - ELAPSED[$ELAPSED] ELAPSED2[$ELAPSED2]\n"
96 # COUNT[$COUNT] N[$N] ELAPSED[$ELAPSED] ELAPSED2[$ELAPSED2]
98 # If it called the function more than $N times, it wasn't memoized properly
99 print (($COUNT > $N) ? "ok 3\n" : "not ok 3\n");
101 # Do it again. Should be even faster this time.
105 $ELAPSED2 = (time - $start) || 1; # prevent division by 0 errors
107 print (($RESULT == $RESULT2) ? "ok 4\n" : "not ok 4\n");
108 print (($ELAPSED/$ELAPSED2 >= 10) ? "ok 5 - ELAPSED[$ELAPSED] ELAPSED2[$ELAPSED2]\n"
110 # This time it shouldn't have called the function at all.
111 print ($COUNT == 0 ? "ok 6\n" : "not ok 6\n");