ruby-changes:24218
From: akr <ko1@a...>
Date: Mon, 2 Jul 2012 22:15:41 +0900 (JST)
Subject: [ruby-changes:24218] akr:r36269 (trunk): * thread.c (rb_thread_aref): add explanation for why Thread#[] and
akr 2012-07-02 22:15:29 +0900 (Mon, 02 Jul 2012) New Revision: 36269 http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=36269 Log: * thread.c (rb_thread_aref): add explanation for why Thread#[] and Thread#[]= are fiber-local and not thread-local. reported by Julien A. [ruby-core:41606] [ruby-trunk - Bug #5750] Modified files: trunk/ChangeLog trunk/thread.c Index: ChangeLog =================================================================== --- ChangeLog (revision 36268) +++ ChangeLog (revision 36269) @@ -1,3 +1,9 @@ +Mon Jul 2 22:13:04 2012 Tanaka Akira <akr@f...> + + * thread.c (rb_thread_aref): add explanation for why Thread#[] and + Thread#[]= are fiber-local and not thread-local. + reported by Julien A. [ruby-core:41606] [ruby-trunk - Bug #5750] + Mon Jul 2 21:25:55 2012 Tanaka Akira <akr@f...> * time.c (timew_out_of_timet_range): specialization for Index: thread.c =================================================================== --- thread.c (revision 36268) +++ thread.c (revision 36269) @@ -2078,6 +2078,39 @@ * #<Thread:0x00000002a54220 dead>: A * #<Thread:0x00000002a541a8 dead>: B * #<Thread:0x00000002a54130 dead>: C + * + * Thread#[] and Thread#[]= are not thread-local but fiber-local. + * This confusion was not exist until Ruby 1.8 because + * fiber is available since Ruby 1.9. + * Ruby 1.9 chooses that the methods behaves fiber-local to save + * following idiom for dynamic scope. + * + * def meth(newvalue) + * begin + * oldvalue = Thread.current[:name] + * Thread.current[:name] = newvalue + * yield + * ensure + * Thread.current[:name] = oldvalue + * end + * end + * + * The idiom may not work as dynamic scope if the methods are thread-local + * and a given block switches fiber. + * + * f = Fiber.new { + * meth(1) { + * Fiber.yield + * } + * } + * meth(2) { + * f.resume + * } + * f.resume + * p Thread.current[:name] + * #=> nil if fiber-local + * #=> 2 if thread-local (The value 2 is leaked to outside of meth method.) + * */ static VALUE -- ML: ruby-changes@q... Info: http://www.atdot.net/~ko1/quickml/