From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id A36941F406 for ; Fri, 11 May 2018 18:02:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751379AbeEKSCa (ORCPT ); Fri, 11 May 2018 14:02:30 -0400 Received: from cloud.peff.net ([104.130.231.41]:36384 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751169AbeEKSC3 (ORCPT ); Fri, 11 May 2018 14:02:29 -0400 Received: (qmail 16688 invoked by uid 109); 11 May 2018 18:02:29 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Fri, 11 May 2018 18:02:29 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 7939 invoked by uid 111); 11 May 2018 18:02:33 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with (ECDHE-RSA-AES256-GCM-SHA384 encrypted) SMTP; Fri, 11 May 2018 14:02:33 -0400 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Fri, 11 May 2018 14:02:27 -0400 Date: Fri, 11 May 2018 14:02:27 -0400 From: Jeff King To: git@vger.kernel.org Cc: Derrick Stolee , Junio C Hamano Subject: [PATCH 3/4] mark_parents_uninteresting(): replace list with stack Message-ID: <20180511180227.GC12543@sigill.intra.peff.net> References: <20180511180029.GA11290@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180511180029.GA11290@sigill.intra.peff.net> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org The mark_parents_uninteresting() function uses two loops: an outer one to process our queue of pending parents, and an inner one to process first-parent chains. This is a clever optimization from 941ba8db57 (Eliminate recursion in setting/clearing marks in commit list, 2012-01-14) to limit the number of linked-list allocations when following single-parent chains. Unfortunately, this makes the result a little hard to read. Let's replace the list with a stack. Then we don't have to worry about doing this double-loop optimization, as we'll just reuse the top element of the stack as we pop/push. Signed-off-by: Jeff King --- The diff makes a lot more sense with "-w". revision.c | 67 +++++++++++++++++++++++++++++++++++------------------- 1 file changed, 43 insertions(+), 24 deletions(-) diff --git a/revision.c b/revision.c index cee4f3a4b4..89ff9a99ce 100644 --- a/revision.c +++ b/revision.c @@ -92,38 +92,57 @@ void mark_tree_uninteresting(struct tree *tree) mark_tree_contents_uninteresting(tree); } -void mark_parents_uninteresting(struct commit *commit) +struct commit_stack { + struct commit **items; + size_t nr, alloc; +}; +#define COMMIT_STACK_INIT { NULL, 0, 0 } + +static void commit_stack_push(struct commit_stack *stack, struct commit *commit) { - struct commit_list *parents = NULL, *l; + ALLOC_GROW(stack->items, stack->nr + 1, stack->alloc); + stack->items[stack->nr++] = commit; +} - for (l = commit->parents; l; l = l->next) - commit_list_insert(l->item, &parents); +static struct commit *commit_stack_pop(struct commit_stack *stack) +{ + return stack->nr ? stack->items[--stack->nr] : NULL; +} - while (parents) { - struct commit *commit = pop_commit(&parents); +static void commit_stack_clear(struct commit_stack *stack) +{ + FREE_AND_NULL(stack->items); + stack->nr = stack->alloc = 0; +} - while (commit) { - if (commit->object.flags & UNINTERESTING) - break; +void mark_parents_uninteresting(struct commit *commit) +{ + struct commit_stack pending = COMMIT_STACK_INIT; + struct commit_list *l; - commit->object.flags |= UNINTERESTING; + for (l = commit->parents; l; l = l->next) + commit_stack_push(&pending, l->item); - /* - * Normally we haven't parsed the parent - * yet, so we won't have a parent of a parent - * here. However, it may turn out that we've - * reached this commit some other way (where it - * wasn't uninteresting), in which case we need - * to mark its parents recursively too.. - */ - if (!commit->parents) - break; + while (pending.nr > 0) { + struct commit *commit = commit_stack_pop(&pending); - for (l = commit->parents->next; l; l = l->next) - commit_list_insert(l->item, &parents); - commit = commit->parents->item; - } + if (commit->object.flags & UNINTERESTING) + return; + commit->object.flags |= UNINTERESTING; + + /* + * Normally we haven't parsed the parent + * yet, so we won't have a parent of a parent + * here. However, it may turn out that we've + * reached this commit some other way (where it + * wasn't uninteresting), in which case we need + * to mark its parents recursively too.. + */ + for (l = commit->parents; l; l = l->next) + commit_stack_push(&pending, l->item); } + + commit_stack_clear(&pending); } static void add_pending_object_with_path(struct rev_info *revs, -- 2.17.0.988.gec4b43b3e5