220 15345 <71d4ea44-aec9-4bfa-a1a8-ba81ca745b84@isocpp.org> article Path: news.gmane.org!not-for-mail From: Ramkumar Revanur Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: get count of std::weak_ptr objects tracking a shared resource Date: Sat, 27 Dec 2014 21:07:47 -0800 (PST) Lines: 74 Approved: news@gmane.org Message-ID: <71d4ea44-aec9-4bfa-a1a8-ba81ca745b84@isocpp.org> References: <4797942.dAdOve4yz0@tjmaciei-mobl4> <549C50C1.8060008@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_5260_1886655065.1419743267485" X-Trace: ger.gmane.org 1419743277 26915 80.91.229.3 (28 Dec 2014 05:07:57 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 28 Dec 2014 05:07:57 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCD4HFPP7UBRBJFA72SAKGQE4CSC7GA@isocpp.org Sun Dec 28 06:07:50 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qa0-f69.google.com ([209.85.216.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Y564z-0004JE-Q4 for gclcip-std-proposals@m.gmane.org; Sun, 28 Dec 2014 06:07:49 +0100 Original-Received: by mail-qa0-f69.google.com with SMTP id f12sf20136495qad.4 for ; Sat, 27 Dec 2014 21:07:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=d8tve5Vjik49MsBND9KjlUcumVsEsVPpqq0ie0N3nzk=; b=SQGRFEL5PRyQ6kKf+VvyUtvUy96KUMY3J4ZYGcwESEsw6Zq3SdKky4sMRIea2wJOkW 4HKpu6PP0K4vyc3u0IK4wDCniUm88+kiMedvLQpaPL5q/2j3EB8GOW6GruoTgr8XFnRw 6tdWyLJU5+Qy6QzJ4jruWL7AmQyzJlIKdSKCkdDWucyG9D1IlEQmT+dw8G2VjSBYGNt2 cZsML2LylphdryJtn1y9Q67rMD5c71kGdHF8YTGz250uXdL2z8IxfW/zRGKg79aMldur PO1CUrtRQ4xeN6dE9rFbsto+CG/BJ/AFpte8r5opnJYJyqAVzeAhWz22tU/zFPQoCZIe drfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:content-type:x-original-sender:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=d8tve5Vjik49MsBND9KjlUcumVsEsVPpqq0ie0N3nzk=; b=hsNmmjbOR+qlueIBSNw5tRT5B/6qveIVMcjy91XCnTvBQsKKfYRQBmCu6OVXs79nVj zCuQNMC+lq7thpR/m9wZEBPQA9i7+MbMW5ehIT+2lFTVoyVyJI119pj2vxnnlBbcHi5V 2MbCWoiO9YQBcfcrf39ZgDNAYlwaDpEh9oefrDwx3kJl7MkCGRqzwneWZqrk+nuKs4uO EKlWLT5+4K9o/oYsQIz+2WTsaz2gyE9pM+AXShGaQCzO/nY/MrzF1C+wDnn/L0yNuQ6+ +ubOu2BMjNxjSw4iLvgxcjjhTOMnh8knwPG5QmgUck3nsuPodR39tjb6Z0K+RvPjhl3N x5fg== X-Gm-Message-State: ALoCoQlBG6rmkHD9jG+BV5ekO7c+e2u/vc/hfdGNNeA8PDJtJWGM0Vq1WP4WXwFG0aiAt6TCaUFl X-Received: by 10.236.203.98 with SMTP id e62mr124479yho.56.1419743268999; Sat, 27 Dec 2014 21:07:48 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.36.10 with SMTP id m10ls2014438igj.12.gmail; Sat, 27 Dec 2014 21:07:48 -0800 (PST) X-Received: by 10.50.43.199 with SMTP id y7mr607399igl.5.1419743268288; Sat, 27 Dec 2014 21:07:48 -0800 (PST) In-Reply-To: <549C50C1.8060008@gmail.com> X-Original-Sender: write2ramkumar@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:15345 Archived-At: ------=_Part_5260_1886655065.1419743267485 Content-Type: multipart/alternative; boundary="----=_Part_5261_1415629500.1419743267485" ------=_Part_5261_1415629500.1419743267485 Content-Type: text/plain; charset=UTF-8 Just as new shared_ptr can be created to the same resource from existing shared_ptr. The reliability of the "weak_count" is same as the reliability of use_count on a shared_ptr. On Thursday, December 25, 2014 11:29:48 PM UTC+5:30, Miro Knejp wrote: > > On 25 December 2014 at 17:43, Thiago Macieira > wrote: > > The only thread-safe information is whether a given weak_ptr is the last > > reference (i.e., count == 1). > And not even that is reliable as new independent weak_ptr instances can > be created as long as a shared_ptr exists. > > -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_5261_1415629500.1419743267485 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Just as new shared_ptr can be created to the same resource= from existing shared_ptr. The reliability of the "weak_count" is same as t= he reliability of use_count on a shared_ptr.



On = Thursday, December 25, 2014 11:29:48 PM UTC+5:30, Miro Knejp wrote:On 25 December 2014 at 17:43, Thiago M= acieira <thi...@macieira.org>= ; wrote:
> The only thread-safe information is whether a given weak_ptr is th= e last
> reference (i.e., count =3D=3D 1).
And not even that is reliable as new independent weak_ptr instances can= =20
be created as long as a shared_ptr exists.

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