From 37be3e260c883abbbacedff4c53da8e40b3f12a0 Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Tue, 27 Dec 2016 00:54:41 +0000 Subject: [PATCH] introduce String#fstring method This exposes the rb_fstring internal function to return a deduped and frozen string. This is useful for writing all sorts of record processing key values maybe stored, but certain keys and values are often duplicated at a high frequency, so memory savings can noticeable. Use cases are many: * email/NNTP header processing There are some standard header keys everybody uses (From/To/Cc/Date/Subject/Received/Message-ID/References/In-Reply-To), as well as common ones specific to a certain lists: (ruby-core has X-Redmine-* headers) It is also useful to dedupe values, as most inboxes have multiple messages from the same sender, or MUA. * package management systems - things like RubyGems stores identical strings for licenses, dependency names, author names/emails, etc * HTTP headers/trailers - standard headers (Host/Accept/Accept-Encoding/User-Agent/...) are common, but there are also uncommon ones. Values may be deduped, as well, as it is likely a user agent will make multiple/parallel requests to the same server. * version control systems - this can be useful for deduplicating names of frequent committers (like "nobu" :) In linux.git and git.git, there are also common trailers such as Signed-Off-By/Acked-by/Reviewed-by/Fixes/... as well as less common ones. * audio metadata - There are commonly used tags (Artist/Album/Title/Tracknumber), but Vorbis comments allows arbitrary key values to be stored. Music collections contain songs by the same artist or mutiple songs from the same album, so deduplicating values will be helpful there, too. * JSON, YAML, XML, HTML processing certain fields, tags and attributes are commonly used across the same and multiple documents --- string.c | 11 +++++++++++ test/ruby/test_string.rb | 8 ++++++++ 2 files changed, 19 insertions(+) diff --git a/string.c b/string.c index 494dc1d90e..ce44aa5454 100644 --- a/string.c +++ b/string.c @@ -296,6 +296,16 @@ fstr_update_callback(st_data_t *key, st_data_t *value, st_data_t arg, int existi } } +/* + * call-seq: + * str.fstring -> str2 + * str2.fstring -> str2 + * + * Returns a deduplicated and frozen string identical in content + * to str. If str was already deduplicated and + * frozen (e.g. frozen string literal), then str itself + * is returned. + */ RUBY_FUNC_EXPORTED VALUE rb_fstring(VALUE str) @@ -10098,6 +10108,7 @@ Init_String(void) rb_define_method(rb_cString, "b", rb_str_b, 0); rb_define_method(rb_cString, "valid_encoding?", rb_str_valid_encoding_p, 0); rb_define_method(rb_cString, "ascii_only?", rb_str_is_ascii_only_p, 0); + rb_define_method(rb_cString, "fstring", rb_fstring, 0); rb_fs = Qnil; rb_define_hooked_variable("$;", &rb_fs, 0, rb_fs_setter); diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb index f2fcf3fb25..a2cd131c90 100644 --- a/test/ruby/test_string.rb +++ b/test/ruby/test_string.rb @@ -2549,6 +2549,14 @@ def test_chr assert_equal("\u3042", "\u3042\u3043".chr) assert_equal('', ''.chr) end + + def test_fstring + ts = 'fstring test case'.freeze + tmp = ts.dup + assert_same ts, tmp.fstring + assert_not_predicate tmp, :frozen? + assert_predicate tmp.fstring, :frozen? + end end class TestString2 < TestString -- EW