From 20cf000ce7539ca20bd8b8be2a4f1f1c5ad632dc Mon Sep 17 00:00:00 2001 From: naruse Date: Thu, 17 Aug 2017 16:34:40 +0000 Subject: Add optimization for creating zerofill string ``` require 'benchmark' n = 1 * 1024 * 1024 * 1024 Benchmark.bmbm do |x| x.report("*") { 0.chr * n } x.report("ljust") { String.new(capacity: n).ljust(n, "\0") } end ``` Before ```% ./ruby test.rb Rehearsal ----------------------------------------- * 0.358396 0.392753 0.751149 ( 1.134231) ljust 0.203277 0.389223 0.592500 ( 0.594816) -------------------------------- total: 1.343649sec user system total real * 0.282647 0.304600 0.587247 ( 0.589205) ljust 0.201834 0.283801 0.485635 ( 0.487617) ``` After ```% ./ruby test.rb Rehearsal ----------------------------------------- * 0.000522 0.000021 0.000543 ( 0.000534) ljust 0.208551 0.321030 0.529581 ( 0.542083) -------------------------------- total: 0.530124sec user system total real * 0.000069 0.000006 0.000075 ( 0.000069) ljust 0.206698 0.301032 0.507730 ( 0.517674) ``` git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59614 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- string.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'string.c') diff --git a/string.c b/string.c index daef497b3d..8461ceb8b5 100644 --- a/string.c +++ b/string.c @@ -1905,6 +1905,18 @@ rb_str_times(VALUE str, VALUE times) if (len < 0) { rb_raise(rb_eArgError, "negative argument"); } + if (RSTRING_LEN(str) == 1 && RSTRING_PTR(str)[0] == 0) { + str2 = str_alloc(rb_obj_class(str)); + if (!STR_EMBEDDABLE_P(len, 1)) { + RSTRING(str2)->as.heap.aux.capa = len; + RSTRING(str2)->as.heap.ptr = ZALLOC_N(char, (size_t)len + 1); + STR_SET_NOEMBED(str2); + } + STR_SET_LEN(str2, len); + rb_enc_copy(str2, str); + OBJ_INFECT(str2, str); + return str2; + } if (len && LONG_MAX/len < RSTRING_LEN(str)) { rb_raise(rb_eArgError, "argument too big"); } -- cgit v1.2.3