From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753599Ab2HCVaZ (ORCPT ); Fri, 3 Aug 2012 17:30:25 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:44759 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752377Ab2HCVaW (ORCPT ); Fri, 3 Aug 2012 17:30:22 -0400 Date: Fri, 3 Aug 2012 14:30:17 -0700 From: Tejun Heo To: Sasha Levin Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com, davem@davemloft.net, rostedt@goodmis.org, mingo@elte.hu, ebiederm@xmission.com, aarcange@redhat.com, ericvh@gmail.com, netdev@vger.kernel.org Subject: Re: [RFC v2 1/7] hashtable: introduce a small and naive hashtable Message-ID: <20120803213017.GK15477@google.com> References: <1344003788-1417-1-git-send-email-levinsasha928@gmail.com> <1344003788-1417-2-git-send-email-levinsasha928@gmail.com> <20120803171515.GH15477@google.com> <501C407D.9080900@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <501C407D.9080900@gmail.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Fri, Aug 03, 2012 at 11:19:57PM +0200, Sasha Levin wrote: > > Is this supposed to be embedded in struct definition? If so, the name > > is rather misleading as DEFINE_* is supposed to define and initialize > > stand-alone constructs. Also, for struct members, simply putting hash > > entries after struct hash_table should work. > > It would work, but I didn't want to just put them in the union since > I feel it's safer to keep them in a separate struct so they won't be > used by mistake, Just use ugly enough pre/postfixes. If the user still accesses that, it's the user's fault. > >> +static void hash_init(struct hash_table *ht, size_t bits) > >> +{ > >> + size_t i; > > > > I would prefer int here but no biggie. > > Just wondering, is there a particular reason behind it? It isn't a size and using unsigned when signed suffices seems to cause more headache than helps anything usually due to lack of values to use for exceptional conditions (usually -errno or -1). > > As opposed to using hash_for_each_possible(), how much difference does > > this make? Is it really worthwhile? > > Most of the places I've switched to using this hashtable so far (4 > out of 6) are using hash_get(). I think that the code looks cleaner > when you an just provide a comparison function instead of > implementing the iteration itself. > > I think hash_for_for_each_possible() is useful if the comparison > condition is more complex than a simple comparison of one of the > object members with the key - there's no need to force it on all the > users. I don't know. What's the difference? In terms of LOC, it might even not save any thanks to the extra function definition, right? I don't think it's saving enough complexity to justify a separate rather unusual interface. Thanks. -- tejun