From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junio C Hamano Subject: [PATCH 2/3] commit-queue: LIFO or priority queue of commits Date: Thu, 6 Jun 2013 22:11:11 -0700 Message-ID: <1370581872-31580-3-git-send-email-gitster@pobox.com> References: <7vfvwuww39.fsf@alter.siamese.dyndns.org> <1370581872-31580-1-git-send-email-gitster@pobox.com> Cc: Elliott Cable , Jeff King To: git@vger.kernel.org X-From: git-owner@vger.kernel.org Fri Jun 07 07:11:27 2013 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UkoxR-0000Ef-Lb for gcvg-git-2@plane.gmane.org; Fri, 07 Jun 2013 07:11:26 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750908Ab3FGFLV (ORCPT ); Fri, 7 Jun 2013 01:11:21 -0400 Received: from b-pb-sasl-quonix.pobox.com ([208.72.237.35]:52615 "EHLO smtp.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750838Ab3FGFLT (ORCPT ); Fri, 7 Jun 2013 01:11:19 -0400 Received: from smtp.pobox.com (unknown [127.0.0.1]) by b-sasl-quonix.pobox.com (Postfix) with ESMTP id 349CF20C39; Fri, 7 Jun 2013 05:11:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:date:message-id:in-reply-to:references; s=sasl; bh=85sf c+6p1XgboT6hbhUI0oDxzbk=; b=Klz+aJ7zpriNTnemRFa10+PJ7xZ6ceDVAYnL 2bKPOpzs9jqPwagwYt/DpT1uiEmegeATSs6yKD96pnq3tF01rXlviBNd2yvebFt/ +P+8R7yho+K8ducYsFCGJ5rAdxYUHbHBxTweSRPAfbk/P6eD59YKb2EHpNzK8YfR kBT1ogc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=from:to:cc :subject:date:message-id:in-reply-to:references; q=dns; s=sasl; b= ZC6kNEuo01jWuMPHhwhkHrD23B9GxuF/oHq6JtDkm7JTYuNnUFKTQnQW317zv+Ix Ea6WHRGwaOgYnBlcl8I/GO2RUhN1pSr0BXTKYNKSnPlf+OHGEqbYnoSet6mKVU2F EMQH4gemFmvBySlVh0Jc4zgyIn/uHSNVmcyDw2eAdc8= Received: from b-pb-sasl-quonix.pobox.com (unknown [127.0.0.1]) by b-sasl-quonix.pobox.com (Postfix) with ESMTP id 2C66820C38; Fri, 7 Jun 2013 05:11:19 +0000 (UTC) Received: from pobox.com (unknown [50.161.4.97]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by b-sasl-quonix.pobox.com (Postfix) with ESMTPSA id 4476520C37; Fri, 7 Jun 2013 05:11:18 +0000 (UTC) X-Mailer: git-send-email 1.8.3-451-gb703ddf In-Reply-To: <1370581872-31580-1-git-send-email-gitster@pobox.com> X-Pobox-Relay-ID: AF6A110A-CF30-11E2-A78B-E56BAAC0D69C-77302942!b-pb-sasl-quonix.pobox.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Traditionally we used a singly linked list of commits to hold a set of in-flight commits while traversing history. The most typical use of the list is to insert commit that is newly discovered in it, keep it sorted by commit timestamp, pick up the newest one from the list, and keep digging. The cost of keeping the singly linked list sorted is nontrivial, and this typical use pattern better matches a priority queue. Introduce a commit-queue structure, that can be used either as a LIFO stack, or a priority queue. This will be used in the next patch to hold in-flight commits during sort-in-topological-order. Signed-off-by: Junio C Hamano --- Makefile | 2 ++ commit-queue.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ commit-queue.h | 31 +++++++++++++++++++++++++ 3 files changed, 104 insertions(+) create mode 100644 commit-queue.c create mode 100644 commit-queue.h diff --git a/Makefile b/Makefile index 598d631..3cf55e9 100644 --- a/Makefile +++ b/Makefile @@ -634,6 +634,7 @@ LIB_H += cache.h LIB_H += color.h LIB_H += column.h LIB_H += commit.h +LIB_H += commit-queue.h LIB_H += compat/bswap.h LIB_H += compat/cygwin.h LIB_H += compat/mingw.h @@ -757,6 +758,7 @@ LIB_OBJS += color.o LIB_OBJS += column.o LIB_OBJS += combine-diff.o LIB_OBJS += commit.o +LIB_OBJS += commit-queue.o LIB_OBJS += compat/obstack.o LIB_OBJS += compat/terminal.o LIB_OBJS += config.o diff --git a/commit-queue.c b/commit-queue.c new file mode 100644 index 0000000..77d4b02 --- /dev/null +++ b/commit-queue.c @@ -0,0 +1,71 @@ +#include "cache.h" +#include "commit.h" +#include "commit-queue.h" + +void clear_commit_queue(struct commit_queue *queue) +{ + free(queue->array); + queue->nr = 0; + queue->alloc = 0; + queue->array = NULL; +} + +void commit_queue_put(struct commit_queue *queue, struct commit *commit) +{ + commit_compare_fn compare = queue->compare; + int ix, parent; + + /* Append at the end */ + ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc); + queue->array[queue->nr++] = commit; + if (!compare) + return; /* LIFO */ + + /* Bubble up the new one */ + for (ix = queue->nr - 1; ix; ix = parent) { + parent = (ix - 1) / 2; + if (compare(queue->array[parent], queue->array[ix], + queue->cb_data) < 0) + break; + + commit = queue->array[parent]; + queue->array[parent] = queue->array[ix]; + queue->array[ix] = commit; + } +} + +struct commit *commit_queue_get(struct commit_queue *queue) +{ + struct commit *result, *swap; + int ix, child; + commit_compare_fn compare = queue->compare; + + if (!queue->nr) + return NULL; + if (!compare) + return queue->array[--queue->nr]; /* LIFO */ + + result = queue->array[0]; + if (!--queue->nr) + return result; + + queue->array[0] = queue->array[queue->nr]; + + /* Push down the one at the root */ + for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) { + child = ix * 2 + 1; /* left */ + if ((child + 1 < queue->nr) && + (compare(queue->array[child], queue->array[child + 1], + queue->cb_data) >= 0)) + child++; /* use right child */ + + if (compare(queue->array[ix], queue->array[child], + queue->cb_data) < 0) + break; + + swap = queue->array[child]; + queue->array[child] = queue->array[ix]; + queue->array[ix] = swap; + } + return result; +} diff --git a/commit-queue.h b/commit-queue.h new file mode 100644 index 0000000..7c5dc4c --- /dev/null +++ b/commit-queue.h @@ -0,0 +1,31 @@ +#ifndef COMMIT_QUEUE_H +#define COMMIT_QUEUE_H + +/* + * Compare two commits; the third parameter is cb_data in the + * commit_queue structure. + */ +typedef int (*commit_compare_fn)(struct commit *, struct commit *, void *); + +struct commit_queue { + commit_compare_fn compare; + void *cb_data; + int alloc, nr; + struct commit **array; +}; + +/* + * Add the commit to the queue + */ +extern void commit_queue_put(struct commit_queue *, struct commit *); + +/* + * Extract the commit that compares the smallest out of the queue, + * or NULL. If compare function is NULL, the queue acts as a LIFO + * stack. + */ +extern struct commit *commit_queue_get(struct commit_queue *); + +extern void clear_commit_queue(struct commit_queue *); + +#endif /* COMMIT_QUEUE_H */ -- 1.8.3-451-gb703ddf