A user noted that the following command was slower than they
expected:
busybox shuf -i "1500000000-$(date +%s)" -n 5
At time of writing the range contains 128 million values. On my
system this takes 7.7s whereas 'shuf' from coreutils takes a
handful of milliseconds.
Optimise BusyBox 'shuf' for cases where -n is specified by stopping
shuffling once the required number of lines have been processed.
On my system the time for the example is reduced to 0.4s.
function old new delta
shuf_main 520 540 +20
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/0 up/down: 20/0) Total: 20 bytes
v2: Code shrink. Since outlines <= numlines:
- the loop in shuffle_lines() only needs to test the value of
outlines;
- shuffle_lines() can be called unconditionally.
Update timing to allow for the 13 million seconds elapsed since v1.
Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
8817e285b7