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58 lines
2.1 KiB
Bash
Executable File
58 lines
2.1 KiB
Bash
Executable File
#!/bin/sh
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# Test for this performance regression:
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# grep-3.5 and 3.6 would take O(N^2) time for some sets of input regexps.
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# Copyright 2020-2026 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 <https://www.gnu.org/licenses/>.
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. "${srcdir=.}/init.sh"; path_prepend_ ../src
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fail=0
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require_perl_
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: > empty || framework_failure_
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# Construct a test case that consumes enough CPU time that we don't
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# have to worry about measurement noise. This first case is searching
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# for digits, which never exhibited a problem with hash collisions.
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n_pat=40000
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while :; do
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seq $n_pat > in || framework_failure_
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small_ms=$(LC_ALL=C user_time_ 1 grep --file=in empty) || fail=1
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test $small_ms -ge 200 && break
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n_pat=$(expr $n_pat '*' 2)
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case $n_pat:$small_ms in
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640000:0) skip_ 'user_time_ appears always to report 0 elapsed ms';;
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esac
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done
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# Now, search for those same digits mapped to A-J.
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# With the PJW-based hash function, this became O(N^2).
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seq $n_pat | tr 0-9 A-J > in || framework_failure_
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large_ms=$(LC_ALL=C user_time_ 1 grep --file=in empty) || fail=1
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# Deliberately recording in an unused variable so it
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# shows up in set -x output, in case this test fails.
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ratio=$(expr "$large_ms" / "$small_ms")
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# The duration of the latter run must be no more than 10 times
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# that of the former. Using recent versions prior to this fix,
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# this test would fail due to ratios > 800. Using the fixed version,
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# it's common to see a ratio less than 1.
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returns_ 1 expr $small_ms '<' $large_ms / 10 || fail=1
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Exit $fail
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