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* 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.
61 lines
2.1 KiB
Bash
Executable File
61 lines
2.1 KiB
Bash
Executable File
#!/bin/sh
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# Ensure that shuf randomizes its input.
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# Copyright (C) 2006-2011 Free Software Foundation, Inc.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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. "${srcdir=.}/init.sh"; path_prepend_ ../src
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print_ver_ shuf
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getlimits_
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seq 100 > in || framework_failure
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shuf in >out || fail=1
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# Fail if the input is the same as the output.
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# This is a probabilistic test :-)
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# However, the odds of failure are very low: 1 in 100! (~ 1 in 10^158)
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compare in out > /dev/null && { fail=1; echo "not random?" 1>&2; }
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# Fail if the sorted output is not the same as the input.
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sort -n out > out1
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compare in out1 || { fail=1; echo "not a permutation" 1>&2; }
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# Exercise shuf's -i option.
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shuf -i 1-100 > out || fail=1
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compare in out > /dev/null && { fail=1; echo "not random?" 1>&2; }
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sort -n out > out1
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compare in out1 || { fail=1; echo "not a permutation" 1>&2; }
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# Exercise shuf's -e option.
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t=`shuf -e a b c d e | sort | fmt`
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test "$t" = 'a b c d e' || { fail=1; echo "not a permutation" 1>&2; }
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# Before coreutils-6.3, this would infloop.
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# "seq 1860" produces 8193 (8K + 1) bytes of output.
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seq 1860 | shuf > /dev/null || fail=1
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# coreutils-6.12 and earlier would output a newline terminator, not \0.
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shuf --zero-terminated -i 1-1 > out || fail=1
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printf '1\0' > exp || framework_failure
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cmp out exp || { fail=1; echo "missing NUL terminator?" 1>&2; }
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# Ensure shuf -n operates efficiently for small n. Before coreutils-8.13
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# this would try to allocate $SIZE_MAX * sizeof(size_t)
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timeout 10 shuf -i1-$SIZE_MAX -n2 >/dev/null ||
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{ fail=1; echo "couldn't get a small subset" >&2; }
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Exit $fail
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