[PATCH v2 1/6] xlog: store prev vclock in xlog header

[Konstantin Osipov]

* Vladimir Davydov <vdavydov.dev at gmail.com> [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;
 		} 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;
 	}
 
 	if (xlog_create(xlog, filename, dir->open_wflags, &meta) != 0)
diff --git a/src/box/xlog.h b/src/box/xlog.h
index 259b5210b..08eb0952c 100644
--- a/src/box/xlog.h
+++ b/src/box/xlog.h
@@ -246,8 +246,6 @@ struct xlog_meta {
 	 * directory for missing WALs.
 	 */
 	struct vclock prev_vclock;
-	/** Set if @prev_vclock is present. */
-	bool has_prev_vclock;
 };
 
 /* }}} */
 ---

 Would it work?

-- 
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov