Reconfiguration in router and storage always creates new
replica objects, and outdates old objects. Since most of the
time reconfiguration does not change cluster topology and URIs,
old connections are relocated to the new replicaset objects so as
not to reconnect on each router.cfg() and storage.cfg().

Connections were moved from old objects to new ones by UUID match
not taking into account possible URI change.

If URI was changed, the new replica object took the old connection
with old URI, and kept trying to connect to the old address.

The patch makes connection relocation work only if old and new URI
match.

Closes #245
---
Branch: http://github.com/tarantool/vshard/tree/gerold103/gh-245-router-reconnect
Issue: https://github.com/tarantool/vshard/issues/245

 test/router/reconnect_to_master.result   | 55 ++++++++++++++++++++++++
 test/router/reconnect_to_master.test.lua | 26 +++++++++++
 vshard/replicaset.lua                    |  2 +-
 3 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/test/router/reconnect_to_master.result b/test/router/reconnect_to_master.result
index d640f0b..aa33f9c 100644
--- a/test/router/reconnect_to_master.result
+++ b/test/router/reconnect_to_master.result
@@ -169,6 +169,61 @@ is_disconnected()
 ---
 - false
 ...
+--
+-- gh-245: dynamic uri reconfiguration didn't work - even if URI was changed in
+-- the config for any instance, it used old connection, because reconfiguration
+-- compared connections by UUID instead of URI.
+--
+util = require('util')
+---
+...
+-- Firstly, clean router from storage_1_a connection.
+rs1_uuid = util.replicasets[1]
+---
+...
+rs1_cfg = cfg.sharding[rs1_uuid]
+---
+...
+cfg.sharding[rs1_uuid] = nil
+---
+...
+vshard.router.cfg(cfg)
+---
+...
+-- Now break the URI in the config.
+old_uri = rs1_cfg.replicas[util.name_to_uuid.storage_1_a].uri
+---
+...
+rs1_cfg.replicas[util.name_to_uuid.storage_1_a].uri = 'https://bad_uri.com:123'
+---
+...
+-- Apply the bad config.
+cfg.sharding[rs1_uuid] = rs1_cfg
+---
+...
+vshard.router.cfg(cfg)
+---
+...
+-- Should fail - master is not available because of the bad URI.
+res, err = vshard.router.callrw(1, 'echo', {1})
+---
+...
+res == nil and err ~= nil
+---
+- true
+...
+-- Repair the config.
+rs1_cfg.replicas[util.name_to_uuid.storage_1_a].uri = old_uri
+---
+...
+vshard.router.cfg(cfg)
+---
+...
+-- Should drop the old connection object and connect fine.
+vshard.router.callrw(1, 'echo', {1})
+---
+- 1
+...
 _ = test_run:switch("default")
 ---
 ...
diff --git a/test/router/reconnect_to_master.test.lua b/test/router/reconnect_to_master.test.lua
index c315c9f..87270af 100644
--- a/test/router/reconnect_to_master.test.lua
+++ b/test/router/reconnect_to_master.test.lua
@@ -70,6 +70,32 @@ while is_disconnected() and i < max_iters do i = i + 1 fiber.sleep(0.1) end
 -- Master connection is active again.
 is_disconnected()

+--
+-- gh-245: dynamic uri reconfiguration didn't work - even if URI was changed in
+-- the config for any instance, it used old connection, because reconfiguration
+-- compared connections by UUID instead of URI.
+--
+util = require('util')
+-- Firstly, clean router from storage_1_a connection.
+rs1_uuid = util.replicasets[1]
+rs1_cfg = cfg.sharding[rs1_uuid]
+cfg.sharding[rs1_uuid] = nil
+vshard.router.cfg(cfg)
+-- Now break the URI in the config.
+old_uri = rs1_cfg.replicas[util.name_to_uuid.storage_1_a].uri
+rs1_cfg.replicas[util.name_to_uuid.storage_1_a].uri = 'https://bad_uri.com:123'
+-- Apply the bad config.
+cfg.sharding[rs1_uuid] = rs1_cfg
+vshard.router.cfg(cfg)
+-- Should fail - master is not available because of the bad URI.
+res, err = vshard.router.callrw(1, 'echo', {1})
+res == nil and err ~= nil
+-- Repair the config.
+rs1_cfg.replicas[util.name_to_uuid.storage_1_a].uri = old_uri
+vshard.router.cfg(cfg)
+-- Should drop the old connection object and connect fine.
+vshard.router.callrw(1, 'echo', {1})
+
 _ = test_run:switch("default")
 _ = test_run:cmd('stop server router_1')
 _ = test_run:cmd('cleanup server router_1')
diff --git a/vshard/replicaset.lua b/vshard/replicaset.lua
index 0191936..b13d05e 100644
--- a/vshard/replicaset.lua
+++ b/vshard/replicaset.lua
@@ -456,7 +456,7 @@ local function rebind_replicasets(replicasets, old_replicasets)
         for replica_uuid, replica in pairs(replicaset.replicas) do
             local old_replica = old_replicaset and
                                 old_replicaset.replicas[replica_uuid]
-            if old_replica then
+            if old_replica and old_replica.uri == replica.uri then
                 local conn = old_replica.conn
                 replica.conn = conn
                 replica.down_ts = old_replica.down_ts
--
2.21.1 (Apple Git-122.3)