sort: smaller and more agressive FEATURE_SORT_OPTIMIZE_MEMORY

function                                             old     new   delta
sort_main                                           1098    1037     -61

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 12 insertions, 12 deletions

diff --git a/coreutils/sort.c b/coreutils/sort.c
index 9909a44a8..4d741e76d 100644
--- a/coreutils/sort.c
+++ b/coreutils/sort.c
@@ -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