From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 5 Jul 2018 11:23:51 +0300 From: Vladimir Davydov Subject: Re: [PATCH v2 1/6] xlog: store prev vclock in xlog header Message-ID: <20180705082351.qgqohxywjnc2jttp@esperanza> References: <25eb188a0085216aef3a2e292fe14d0df71ede13.1530287767.git.vdavydov.dev@gmail.com> <20180705065241.GB11571@chai> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180705065241.GB11571@chai> To: Konstantin Osipov Cc: tarantool-patches@freelists.org List-ID: On Thu, Jul 05, 2018 at 09:52:41AM +0300, Konstantin Osipov wrote: > * Vladimir Davydov [18/06/29 19:49]: > > This patch adds a new key to xlog header, PrevVclock, which contains the > > vclock of the previous xlog file in the xlog directory. It is set by > > xdir_create_xlog() to the last vclock in xdir::index. The new key is > > only present in XLOG files (it doesn't make sense for SNAP or VYLOG > > anyway). It will be used to make the check for xlog gaps more thorough. > > What about the following diff: > > --- > diff --git a/src/box/xlog.c b/src/box/xlog.c > index 59459b25d..a60f2ffa8 100644 > --- a/src/box/xlog.c > +++ b/src/box/xlog.c > @@ -126,12 +126,10 @@ xlog_meta_format(const struct xlog_meta *meta, char *buf, int size) > VCLOCK_KEY ": %s\n", > meta->filetype, v13, PACKAGE_VERSION, instance_uuid, vstr); > free(vstr); > - if (meta->has_prev_vclock) { > - vstr = vclock_to_string(&meta->prev_vclock); > - SNPRINT(total, snprintf, buf, size, > - PREV_VCLOCK_KEY ": %s\n", vstr); > - free(vstr); > - } > + vstr = vclock_to_string(&meta->prev_vclock); > + SNPRINT(total, snprintf, buf, size, > + PREV_VCLOCK_KEY ": %s\n", vstr); > + free(vstr); > SNPRINT(total, snprintf, buf, size, "\n"); > assert(total > 0); > return total; > @@ -263,7 +261,6 @@ xlog_meta_parse(struct xlog_meta *meta, const char **data, > */ > if (parse_vclock(val, val_end, &meta->prev_vclock) != 0) > return -1; > - meta->has_prev_vclock = true; We need to know if PrevVclock is available so that we can skip the check when recovering from an xlog generated by a previous version. > } else if (memcmp(key, VERSION_KEY, key_end - key) == 0) { > /* Ignore Version: for now */ > } else { > @@ -926,12 +923,10 @@ xdir_create_xlog(struct xdir *dir, struct xlog *xlog, > * For WAL dir: store vclock of the previous xlog file > * to check for gaps on recovery. > */ > - if (dir->type == XLOG && !vclockset_empty(&dir->index)) { > + if (!vclockset_empty(&dir->index)) { > vclock_copy(&meta.prev_vclock, vclockset_last(&dir->index)); > - meta.has_prev_vclock = true; > } else { > vclock_create(&meta.prev_vclock); > - meta.has_prev_vclock = false; > } Storing vclock in snap and vylog files doesn't make any sense IMHO. I'd prefer to check dir->type explicitly. If you dislike the extra variable, we can probably introduce a helper to check if vclock is set, something like static inline bool vclock_is_set(const struct vclock *vclock) { return vclock->signature >= 0; }