21 авг. 2019 г., в 12:44, Vladimir Davydov <vdavydov.dev@gmail.com> написал(а):

On Mon, Aug 19, 2019 at 03:11:01PM +0300, Serge Petrenko wrote:

We only entered orphan mode on bootrap and local recovery, but threw an
error when replicaton config was changed on the fly.
For consistency, in this case we should also enter orphan mode when
an instance fails to connect to quorum remote instances.

Closes #4424

A doc bot request is probably required.

---
https://github.com/tarantool/tarantool/issues/4424
https://github.com/tarantool/tarantool/tree/sp/gh-4424-repl-config-errors

src/box/box.cc                 |  9 ++--
src/box/replication.cc         | 30 ++++++-------
src/box/replication.h          |  2 +-
test/replication/misc.result   | 77 ++++++++++++++++++++++++++++++++--
test/replication/misc.test.lua | 29 ++++++++++++-
5 files changed, 125 insertions(+), 22 deletions(-)

diff --git a/src/box/box.cc b/src/box/box.cc
index 66cd6d3a4..43cc32d87 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -666,7 +666,7 @@ cfg_get_replication(int *p_count)
 * Sync box.cfg.replication with the cluster registry, but
 * don't start appliers.
 */
-static void
+static int
box_sync_replication(bool connect_quorum)
{
int count = 0;
@@ -679,9 +679,10 @@ box_sync_replication(bool connect_quorum)
applier_delete(appliers[i]); /* doesn't affect diag */
});

- replicaset_connect(appliers, count, connect_quorum);
+ int rc = replicaset_connect(appliers, count, connect_quorum);

A function typically returns -1 as an error condition, but in this case
-1 means something different. Besdies, this function can also throw an
exception, and there isn't a single word in the comment regarding it,
which is confusing.

Can you somehow manage without using a return code?

guard.is_active = false;
+ return rc;
}

void
@@ -703,7 +704,9 @@ box_set_replication(void)
 * to connect to at least replication_connect_quorum
 * masters.
 */
- box_sync_replication(true);
+ if (box_sync_replication(true) != 0) {
+ return;
+ }

The comment above is clearly outdated by this patch.

/* Follow replica */
replicaset_follow();
/* Wait until appliers are in sync */
diff --git a/src/box/replication.cc b/src/box/replication.cc
index 28f7acedc..e9d0a9206 100644
--- a/src/box/replication.cc
+++ b/src/box/replication.cc
@@ -598,14 +598,14 @@ applier_on_connect_f(struct trigger *trigger, void *event)
applier_pause(applier);
}

-void
+int
replicaset_connect(struct applier **appliers, int count,
   bool connect_quorum)
{
if (count == 0) {
/* Cleanup the replica set. */
replicaset_update(appliers, count);
- return;
+ return 0;
}

say_info("connecting to %d replicas", count);
@@ -660,9 +660,13 @@ replicaset_connect(struct applier **appliers, int count,
 count - state.connected, count);
/* Timeout or connection failure. */
if (connect_quorum && state.connected < quorum) {
- diag_set(ClientError, ER_CFG, "replication",
-  "failed to connect to one or more replicas");
- goto error;
+ /* Destroy appliers */
+ for (int i = 0; i < count; i++) {
+ trigger_clear(&triggers[i].base);
+ applier_stop(appliers[i]);
+ }
+ box_set_orphan(true);
+ return -1;
}
} else {
say_info("connected to %d replicas", state.connected);
@@ -685,16 +689,14 @@ replicaset_connect(struct applier **appliers, int count,
try {
replicaset_update(appliers, count);
} catch (Exception *e) {
- goto error;
- }
- return;
-error:
- /* Destroy appliers */
- for (int i = 0; i < count; i++) {
- trigger_clear(&triggers[i].base);
- applier_stop(appliers[i]);
+ /* Destroy appliers */
+ for (int i = 0; i < count; i++) {
+ trigger_clear(&triggers[i].base);
+ applier_stop(appliers[i]);
+ }

Copy-and-paste... Let's please try to avoid that. I'd prefer if you
called replicaset_follow and _sync in any case and let them decide
if the instance should enter the orphan state.

+ diag_raise();
}
- diag_raise();
+ return 0;
}

bool
diff --git a/test/replication/misc.test.lua b/test/replication/misc.test.lua
index 99e995509..91a77b584 100644
--- a/test/replication/misc.test.lua
+++ b/test/replication/misc.test.lua
@@ -9,6 +9,8 @@ replication_timeout = box.cfg.replication_timeout
replication_connect_timeout = box.cfg.replication_connect_timeout
box.cfg{replication_timeout=0.05, replication_connect_timeout=0.05, replication={}}
box.cfg{replication = {'127.0.0.1:12345', box.cfg.listen}}
+box.info.status
+box.info.ro

-- gh-3606 - Tarantool crashes if box.cfg.replication is updated concurrently
fiber = require('fiber')
@@ -19,7 +21,9 @@ f()
c:get()
c:get()

-box.cfg{replication_timeout = replication_timeout, replication_connect_timeout = replication_connect_timeout}
+box.cfg{replication = "", replication_timeout = replication_timeout, replication_connect_timeout = replication_connect_timeout}
+box.info.status
+box.info.ro

-- gh-3111 - Allow to rebootstrap a replica from a read-only master
replica_uuid = uuid.new()
@@ -293,3 +297,26 @@ test_run:cmd("cleanup server replica")
test_run:cmd("delete server replica")
test_run:cleanup_cluster()
box.schema.user.revoke('guest', 'replication')
+
+--
+-- gh-4424 Always enter orphan mode on error in replication
+-- configuration change.
+--
+replication_connect_timeout = box.cfg.replication_connect_timeout
+replication_connect_quorum = box.cfg.replication_connect_quorum
+
+box.cfg{replication="12345", replication_connect_timeout=0.1, replication_connect_quorum=1}

Let's please also test a more sophisticated use case: when there are two
replicas and we manage to connect to one of them but fail to connect to
another.

+box.info.status
+box.info.ro
+box.cfg{replication = ""}
+box.info.status
+box.info.ro
+-- no switch to orphan when quorum == 0
+box.cfg{replication= "12345", replication_connect_quorum=0}
+box.info.status
+box.info.ro
+test_run:cmd("setopt delimiter ';'")
+box.cfg{replication="",
+        replication_connect_timeout=replication_connect_timeout,
+        replication_connect_quorum=replication_connect_quorum};
+test_run:cmd("setopt delimiter ''");

Nit: I'd rewrite it without using 'setopt delimiter'::

box.cfg{replication = {}}
box.cfg{replication_connect_timeout = replication_connect_timeout)
box.cfg{replication_connect_quorum = replication_connect_quorum)