From: "Юрий Соколов" Date: 2013-04-17T03:31:25+09:00 Subject: [ruby-core:54360] Re: [CommonRuby - Feature #8259] Atomic attributes accessors --001a11c34dc293a07e04da7e9329 Content-Type: text/plain; charset=ISO-8859-1 Charles, I really sure there is no need for `while true` in your numeric handling cas - the nature of cas is "change if no one changes yet", so that your `while true` violates natures of cas. 2013/4/16 headius (Charles Nutter) > > Issue #8259 has been updated by headius (Charles Nutter). > > > I have completed adding the numeric logic to the atomic gem and pushed > 1.1.8. > > The version for JRuby is here: > https://github.com/headius/ruby-atomic/blob/master/ext/org/jruby/ext/atomic/AtomicReferenceLibrary.java#L129 > > The version for MRI, Rubinius, and others is here: > https://github.com/headius/ruby-atomic/blob/master/lib/atomic/numeric_cas_wrapper.rb > ---------------------------------------- > Feature #8259: Atomic attributes accessors > https://bugs.ruby-lang.org/issues/8259#change-38617 > > Author: funny_falcon (Yura Sokolov) > Status: Open > Priority: Normal > Assignee: > Category: > Target version: > > > =begin > Motivated by this gist (()) > and atomic gem > > I propose Class.attr_atomic which will add methods for atomic swap and CAS: > > class MyNode > attr_accessor :item > attr_atomic :successor > > def initialize(item, successor) > @item = item > @successor = successor > end > end > node = MyNode.new(i, other_node) > > # attr_atomic ensures at least #{attr} reader method exists. May be, it > should > # be sure it does volatile access. > node.successor > > # #{attr}_cas(old_value, new_value) do CAS: atomic compare and swap > if node.successor_cas(other_node, new_node) > print "there were no interleaving with other threads" > end > > # #{attr}_swap atomically swaps value and returns old value. > # It ensures that no other thread interleaves getting old value and > setting > # new one by cas (or other primitive if exists, like in Java 8) > node.successor_swap(new_node) > > It will be very simple for MRI cause of GIL, and it will use atomic > primitives for > other implementations. > > Note: both (({#{attr}_swap})) and (({#{attr}_cas})) should raise an error > if instance variable were not explicitly set before. > > Example for nonblocking queue: (( https://gist.github.com/funny-falcon/5370416>)) > > Something similar should be proposed for Structs. May be override same > method as (({Struct.attr_atomic})) > > Open question for reader: > should (({attr_atomic :my_attr})) ensure that #my_attr reader method > exists? > Should it guarantee that (({#my_attr})) provides 'volatile' access? > May be, (({attr_reader :my_attr})) already ought to provide 'volatile' > semantic? > May be, semantic of (({@my_attr})) should have volatile semantic (i doubt > for that)? > =end > > > > -- > http://bugs.ruby-lang.org/ > > --001a11c34dc293a07e04da7e9329 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Charles, I really sure there is no need for `while true` i= n your numeric handling cas -
the nature of cas is "change i= f no one changes yet", so that your `while true` violates natures of c= as.


2013/4/= 16 headius (Charles Nutter) <headius@headius.com>

Issue #8259 has been updated by headius (Charles Nutter).


I have completed adding the numeric logic to the atomic gem and pushe= d 1.1.8.

The version for JRuby is here: https://github.com/headius/ruby-atomic/blob/master/ext/= org/jruby/ext/atomic/AtomicReferenceLibrary.java#L129

The version for MRI, Rubinius, and others is here: https://github.com/headius/ruby-atomic/blob/master/lib/atom= ic/numeric_cas_wrapper.rb
----------------------------------------
Feature #8259: Atomic attributes accessors
https://bugs.ruby-lang.org/issues/8259#change-38617

Author: funny_falcon (Yura Sokolov)
Status: Open
Priority: Normal
Assignee:
Category:
Target version:


=3Dbegin
Motivated by this gist ((<URL:https://gist.github.com/jstorimer/5298581= >)) and atomic gem

I propose Class.attr_atomic which will add methods for atomic swap and CAS:=

=A0 class MyNode
=A0 =A0 attr_accessor :item
=A0 =A0 attr_atomic :successor

=A0 =A0 def initialize(item, successor)
=A0 =A0 =A0 @item =3D item
=A0 =A0 =A0 @successor =3D successor
=A0 =A0 end
=A0 end
=A0 node =3D MyNode.new(i, other_node)

=A0 # attr_atomic ensures at least #{attr} reader method exists. May be, it= should
=A0 # be sure it does volatile access.
=A0 node.successor

=A0 # #{attr}_cas(old_value, new_value) do CAS: atomic compare and swap
=A0 if node.successor_cas(other_node, new_node)
=A0 =A0 print "there were no interleaving with other threads"
=A0 end

=A0 # #{attr}_swap atomically swaps value and returns old value.
=A0 # It ensures that no other thread interleaves getting old value and set= ting
=A0 # new one by cas (or other primitive if exists, like in Java 8)
=A0 node.successor_swap(new_node)

It will be very simple for MRI cause of GIL, and it= will use atomic primitives for
other implementations.

Note: both (({#{attr}_swap})) and (({#{attr}_cas}))= should raise an error if instance variable were not explicitly set before.=

Example for nonblocking queue: ((<URL:https://gist.github.com/funny-falc= on/5370416>))

Something similar should be proposed for Structs. May be override sam= e method as (({Struct.attr_atomic}))

Open question for reader:
should (({attr_atomic :my_attr})) ensure that #my_attr reader method exists= ?
Should it guarantee that (({#my_attr})) provides 'volatile' a= ccess?
May be, (({attr_reader :my_attr})) already ought to provi= de 'volatile' semantic?
May be, semantic of (({@my_attr})) should have volatile semantic (i d= oubt for that)?
=3Dend



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http://bugs.ruby-l= ang.org/


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