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| author | Pádraig Brady <P@draigBrady.com> | 2011-05-13 18:41:42 +0100 |
|---|---|---|
| committer | Pádraig Brady <P@draigBrady.com> | 2011-05-14 10:30:12 +0100 |
| commit | 27873f1deb69745c79d403bbb8e1145bc18f55b8 (patch) | |
| tree | d3b752eed0035e9ce767ea73c07f3b8577deaead /tests/misc/shuf | |
| parent | 9d152a1ed72968ae3624a76e155fe16b240348dc (diff) | |
| download | coreutils-27873f1deb69745c79d403bbb8e1145bc18f55b8.tar.xz | |
shuf: use memory more efficiently when returning a subset
* gl/lib/randperm.c (randperm_new): When the number of items
to return H, is much smaller than the total number of items N,
use a hash to represent the sparse permutations of the set N.
This is currently enabled for N > 128K and N/H > 32.
* tests/misc/shuf: Ensure shuf can quickly return 2 numbers
from a large range.
* gl/modules/randperm: Depend on hash.
* NEWS: Mention the change.
Diffstat (limited to 'tests/misc/shuf')
| -rwxr-xr-x | tests/misc/shuf | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/tests/misc/shuf b/tests/misc/shuf index cdfe7052b..10d285846 100755 --- a/tests/misc/shuf +++ b/tests/misc/shuf @@ -18,6 +18,7 @@ . "${srcdir=.}/init.sh"; path_prepend_ ../src print_ver_ shuf +getlimits_ seq 100 > in || framework_failure @@ -51,4 +52,9 @@ shuf --zero-terminated -i 1-1 > out || fail=1 printf '1\0' > exp || framework_failure cmp out exp || { fail=1; echo "missing NUL terminator?" 1>&2; } +# Ensure shuf -n operates efficiently for small n. Before coreutils-8.13 +# this would try to allocate $SIZE_MAX * sizeof(size_t) +timeout 10 shuf -i1-$SIZE_MAX -n2 >/dev/null || + { fail=1; echo "couldn't get a small subset" >&2; } + Exit $fail |