From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junio C Hamano Subject: Re: [PATCH 2/8] Add a lockfile function to append to a file Date: Thu, 17 Apr 2008 16:41:28 -0700 Message-ID: <7v3apkm4lz.fsf@gitster.siamese.dyndns.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: git@vger.kernel.org, Johannes Schindelin To: Daniel Barkalow X-From: git-owner@vger.kernel.org Fri Apr 18 01:42:27 2008 connect(): Connection refused Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1JmdkI-0005oj-Nd for gcvg-git-2@gmane.org; Fri, 18 Apr 2008 01:42:27 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755451AbYDQXlk (ORCPT ); Thu, 17 Apr 2008 19:41:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755166AbYDQXlk (ORCPT ); Thu, 17 Apr 2008 19:41:40 -0400 Received: from a-sasl-fastnet.sasl.smtp.pobox.com ([207.106.133.19]:49807 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755233AbYDQXlj (ORCPT ); Thu, 17 Apr 2008 19:41:39 -0400 Received: from localhost.localdomain (localhost [127.0.0.1]) by a-sasl-fastnet.sasl.smtp.pobox.com (Postfix) with ESMTP id EF1902D4D; Thu, 17 Apr 2008 19:41:37 -0400 (EDT) Received: from pobox.com (ip68-225-240-77.oc.oc.cox.net [68.225.240.77]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by a-sasl-fastnet.sasl.smtp.pobox.com (Postfix) with ESMTP id 026642D4B; Thu, 17 Apr 2008 19:41:31 -0400 (EDT) In-Reply-To: (Daniel Barkalow's message of "Thu, 17 Apr 2008 19:32:26 -0400 (EDT)") User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Daniel Barkalow writes: > This takes care of copying the original contents into the replacement > file after the lock is held, so that concurrent additions can't miss > each other's changes. > > Signed-off-by: Daniel Barkalow > --- > cache.h | 1 + > lockfile.c | 17 +++++++++++++++++ > 2 files changed, 18 insertions(+), 0 deletions(-) > > diff --git a/cache.h b/cache.h > index 2a1e7ec..4a113b0 100644 > --- a/cache.h > +++ b/cache.h > @@ -391,6 +391,7 @@ struct lock_file { > char filename[PATH_MAX]; > }; > extern int hold_lock_file_for_update(struct lock_file *, const char *path, int); > +extern int hold_lock_file_for_append(struct lock_file *, const char *path, int); > extern int commit_lock_file(struct lock_file *); > > extern int hold_locked_index(struct lock_file *, int); > diff --git a/lockfile.c b/lockfile.c > index 663f18f..95fd3d1 100644 > --- a/lockfile.c > +++ b/lockfile.c > @@ -160,6 +160,23 @@ int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on > return fd; > } > > +int hold_lock_file_for_append(struct lock_file *lk, const char *path, int die_on_error) > +{ > + int fd = lock_file(lk, path); > + struct stat st; > + if (!stat(path, &st)) { > + int orig_fd = open(path, O_RDONLY); > + size_t mmap_size = xsize_t(st.st_size); > + void *mmap = xmmap(NULL, mmap_size, PROT_READ, MAP_PRIVATE, > + orig_fd, 0); > + write_or_die(fd, mmap, mmap_size); > + munmap(mmap, mmap_size); > + } > + if (fd < 0 && die_on_error) > + die("unable to create '%s.lock': %s", path, strerror(errno)); Copying and checking are the other way around, aren't they? Grab the lock, error out if you cannot, then read and copy. > + return fd; > +} > + > int close_lock_file(struct lock_file *lk) > { > int fd = lk->fd; > -- > 1.5.4.3.610.gea6cd