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sort: smaller and more agressive FEATURE_SORT_OPTIMIZE_MEMORY

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function                                             old     new   delta
sort_main                                           1098    1037     -61

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-04-06 16:44:50 +02:00
parent 00bd76728d
commit d1d6d9c5d8
1 changed files with 12 additions and 12 deletions
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24
coreutils/sort.c
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@ -18,11 +18,11 @@
//config: sort is used to sort lines of text in specified files.
//config:
//config:config FEATURE_SORT_BIG
//config: bool "Full SuSv3 compliant sort (support -ktcbdfiozgM)"
//config: bool "Full SuSv3 compliant sort (support -ktcbdfiogM)"
//config: default y
//config: depends on SORT
//config: help
//config: Without this, sort only supports -r, -u, -s, and an integer version
//config: Without this, sort only supports -rusz, and an integer version
//config: of -n. Selecting this adds sort keys, floating point support, and
//config: more. This adds a little over 3k to a nonstatic build on x86.
//config:
@ -66,12 +66,10 @@
//usage: "\n -r Reverse sort order"
//usage: "\n -s Stable (don't sort ties alphabetically)"
//usage: "\n -u Suppress duplicate lines"
//usage: IF_FEATURE_SORT_BIG(
//usage: "\n -z Lines are terminated by NUL, not newline"
///////: "\n -m Ignored for GNU compatibility"
///////: "\n -S BUFSZ Ignored for GNU compatibility"
///////: "\n -T TMPDIR Ignored for GNU compatibility"
//usage: )
//usage:
//usage:#define sort_example_usage
//usage: "$ echo -e \"e\\nf\\nb\\nd\\nc\\na\" | sort\n"
@ -413,6 +411,7 @@ int sort_main(int argc UNUSED_PARAM, char **argv)
#if ENABLE_FEATURE_SORT_OPTIMIZE_MEMORY
bool can_drop_dups;
size_t prev_len = 0;
char *prev_line = (char*) "";
/* Postpone optimizing if the input is small, < 16k lines:
* even just free()ing duplicate lines takes time.
*/
@ -533,32 +532,33 @@ int sort_main(int argc UNUSED_PARAM, char **argv)
if (count_to_optimize_dups == 0) {
size_t len;
char *new_line;
char first = *line;
/* On kernel/linux/arch/ *.[ch] files,
* this reduces memory usage by 6%.
* yes | head -99999999 | sort
* goes down from 1900Mb to 380 Mb.
*/
if (first == '\0' || first == '\n') {
len = !(first == '\0');
new_line = (char*)"\n" + 1 - len;
goto replace;
}
len = strlen(line);
if (len <= prev_len) {
new_line = lines[linecount-1] + (prev_len - len);
new_line = prev_line + (prev_len - len);
if (strcmp(line, new_line) == 0) {
/* it's a tail of the prev line */
if (can_drop_dups && prev_len == len) {
/* it's identical to prev line */
free(line);
continue;
}
replace:
free(line);
line = new_line;
/* continue using longer prev_line
* for future tail tests.
*/
goto skip;
}
}
prev_len = len;
prev_line = line;
skip: ;
}
#else
//TODO: lighter version which only drops total dups if can_drop_dups == true