Support reset of cache with sharding keys

It's possible to drop cache with structures used for secondary sharding
keys support with command "require('crud.sharding_key').update_sharding_keys_cache()".

Part of #166

Reviewed-by: Oleg Babin <[email protected]>
Reviewed-by: Alexander Turenko <[email protected]>

Author: ligurio

crud/common/sharding_key.lua

@@ -145,6 +145,12 @@ function sharding_key_module.fetch_on_router(space_name, timeout)
         "Fetching sharding key for space '%s' is failed", space_name)
 end
 
+function sharding_key_module.update_cache(space_name)
+    cache.fetch_lock:close()
+    cache.drop_caches()
+    return sharding_key_module.fetch_on_router(space_name)
+end
+
 -- Make sure sharding key definition is a part of primary key.
 local function is_part_of_pk(space_name, primary_index_parts, sharding_key_as_index_obj)
     dev_checks('string', 'table', 'table')

test/helper.lua

@@ -323,4 +323,13 @@ function helpers.tarantool_version_at_least(wanted_major, wanted_minor,
     return true
 end
 
+function helpers.update_cache(cluster, space_name)
+    return cluster.main_server.net_box:eval([[
+        local sharding_key = require('crud.common.sharding_key')
+
+        local space_name = ...
+        return sharding_key.update_cache(space_name)
+    ]], {space_name})
+end
+
 return helpers

test/integration/ddl_sharding_key_test.lua

@@ -591,3 +591,22 @@ pgroup.test_delete_secondary_idx = function(g)
         "Sharding key for space \"customers_secondary_idx_name_key\" is missed in primary index, specify bucket_id")
     t.assert_equals(result, nil)
 end
+
+pgroup.test_update_cache = function(g)
+    local space_name = 'customers_name_key'
+    local sharding_key_as_index_obj = helpers.update_cache(g.cluster, space_name)
+    t.assert_equals(sharding_key_as_index_obj, {parts = {{fieldno = 3}}})
+
+    helpers.call_on_servers(g.cluster, {'s1-master', 's2-master'}, function(server)
+        server.net_box:call('set_sharding_key', {space_name, {'age'}})
+    end)
+    sharding_key_as_index_obj = helpers.update_cache(g.cluster, space_name)
+    t.assert_equals(sharding_key_as_index_obj, {parts = {{fieldno = 4}}})
+
+    -- Recover sharding key.
+    helpers.call_on_servers(g.cluster, {'s1-master', 's2-master'}, function(server)
+        server.net_box:call('set_sharding_key', {space_name, {'name'}})
+    end)
+    sharding_key_as_index_obj = helpers.update_cache(g.cluster, space_name)
+    t.assert_equals(sharding_key_as_index_obj, {parts = {{fieldno = 3}}})
+end