From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Ihor Radchenko Newsgroups: gmane.emacs.devel Subject: Re: Emacs design and architecture. How about copy-on-write? 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List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:310820 Archived-At: Po Lu writes: >> Indeed, a simple #define will not be enough then, but we would not waste >> memory copying the values that will never be changed anyway. > > On my machine, struct emacs_globals is 7490 bytes, just short of 7 KiB. > struct thread_state amounts to 12704 bytes, which does not come across > as excessive in this day and age. Thread-local storage is then > dynamically allocated as bindings materialize. Sounds reasonable then. 7k does not look like a big deal to me. >> We discussed asynchronous access to buffers earlier and concluded that >> modifying a buffer (and its buffer-local values) asynchronously is a >> hard problem. In particular, handling gap asynchronously is simply not >> possible. It might be more practical to allow simultaneous read-only >> access to the same buffer, but interlock writes to buffer object >> (including moving gap, changing buffer text, and changing buffer-local >> values). > > The gap and point are not buffer local values. I'm referring to > variables saved within local_var_alist, which must be modified to > incorporate bindings for each thread. As an aside: point should also be thread-local to make common Elisp code work (like re-search-forward, for example). > The problem lies in how to perform this efficiently. The whole process of working with Lisp_Buffer_Local_Value is a bit arcane with all its juggling of the values (`do_symval_forwarding', `swap_in_symval_forwarding', etc) every time current_buffer changes. I am wondering if you solved (seemingly) simpler cases with setting Lisp_Fwd_Obj, Lisp_Fwd_Int, and Lisp_Fwd_Bool. -- Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . 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