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>

diff --git a/coreutils/sort.c b/coreutils/sort.c
index 9909a44a8b661f8c86b97c99db36465ac9a51227..4d741e76d353d771d8201c9f2c2c2672d49419b5 100644 (file)
--- 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