From: Eric Wong <normalperson@yhbt.net>
To: Ruby developers <ruby-core@ruby-lang.org>
Subject: [ruby-core:71820] Re: [Ruby trunk - Bug #11759] URI breaks with frozen strings
Date: Thu, 3 Dec 2015 23:41:03 +0000 [thread overview]
Message-ID: <20151203234103.GA30841@dcvr.yhbt.net> (raw)
In-Reply-To: <redmine.journal-55216.20151203052009.a5e0fe7c1b5704b6@ruby-lang.org>
colin@invoca.com wrote:
> Compared to the surrounding code in the full method, would the extra
> constant lookup make a measurable difference in code size?
64 bytes on ruby 2.3.0dev (2015-12-03 trunk 52872) [x86_64-linux].
require 'objspace'
iseq = RubyVM::InstructionSequence
p ObjectSpace.memsize_of(iseq.compile("str = String.new"))
p ObjectSpace.memsize_of(iseq.compile("str = ''.dup"))
p ObjectSpace.memsize_of(iseq.compile("str = ''.freeze.dup"))
Outputs:
480
416
416
> because the `.freeze` is temporary for Ruby 2.1 and 2.2, right? When
> would this copy of generic.rb ever be run with Ruby versions earlier
> than 2.3?
No, we shouldn't worry about performance with older versions of Ruby
with the stdlib.
> Assuming it will just be used for Ruby 2.3 and later, the
> magic comment included in the patch will implicitly freeze the string
> literal. Hence this would also be sufficient (and in my opinion,
> nearly as clear in intention as `String.new`):
>
> ~~~
> ''.dup
> ~~~
I prefer that if we go for "frozen_string_literal: true" in the comment.
I've also added this test for to_s. However, checking more closely,
the "path" accessor also gets frozen changes because we call
set_path with literal strings.
There may be code out in the wild which relies on "path" being mutable.
--- a/test/uri/test_generic.rb
+++ b/test/uri/test_generic.rb
@@ -14,6 +14,13 @@ def uri_to_ary(uri)
uri.class.component.collect {|c| uri.send(c)}
end
+ def test_to_s
+ exp = 'http://example.com/'.freeze
+ str = URI(exp).to_s
+ assert_equal exp, str
+ refute_predicate str, :frozen?, '[ruby-core:71785] [Bug #11759]'
+ end
+
def test_parse
# 0
assert_kind_of(URI::HTTP, @base_url)
... So perhaps at least one additional change is needed:
--- a/lib/uri/generic.rb
+++ b/lib/uri/generic.rb
@@ -786,7 +786,7 @@ def check_path(v)
# see also URI::Generic.path=
#
def set_path(v)
- @path = v
+ @path = v.frozen? ? v.dup : v
end
protected :set_path
All these frozen literal changes will require going every single
method and and call site with a very fine tooth comb....
next prev parent reply other threads:[~2015-12-03 23:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <redmine.issue-11759.20151202000114@ruby-lang.org>
2015-12-02 0:01 ` [ruby-core:71785] [Ruby trunk - Bug #11759] [Open] URI breaks with frozen strings mperham
2015-12-02 1:18 ` [ruby-core:71786] [Ruby trunk - Bug #11759] " me
2015-12-02 1:30 ` [ruby-core:71787] " me
2015-12-02 1:47 ` [ruby-core:71788] " Eric Wong
2015-12-02 3:56 ` [ruby-core:71790] " me
2015-12-02 4:10 ` [ruby-core:71791] " akr
2015-12-02 7:11 ` [ruby-core:71797] " colin
2015-12-02 21:36 ` [ruby-core:71804] " Eric Wong
2015-12-03 5:20 ` [ruby-core:71812] " colin
2015-12-03 23:41 ` Eric Wong [this message]
2015-12-05 16:20 ` [ruby-core:71846] " colin
2015-12-07 7:19 ` [ruby-core:71879] " matz
2015-12-07 15:59 ` [ruby-core:71910] " colin
2015-12-08 21:35 ` [ruby-core:71957] " Eric Wong
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