Support reset of cache with sharding keys

Part of #166

Author: ligurio

crud/common/sharding_key.lua

@@ -117,6 +117,11 @@ function sharding_key_module.fetch_on_router(space_name, conn)
     return cache.ddl_sharding_keys
 end
 
+function sharding_key_module.update_sharding_keys_cache(space_name)
+    cache.drop_caches()
+    return sharding_key_module.fetch_on_router(space_name)
+end
+
 -- Make sure sharding key definition is a part of primary key.
 function sharding_key_module.is_part_of_pk(space_name, space_format,
                                            primary_index, sharding_key_def)

test/helper.lua

@@ -233,4 +233,13 @@ function helpers.get_other_storage_bucket_id(cluster, bucket_id)
     ]], {bucket_id})
 end
 
+function helpers.update_sharding_keys_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_sharding_keys_cache(space_name)
+    ]], {space_name})
+end
+
 return helpers

test/integration/ddl_sharding_key_test.lua

@@ -527,6 +527,25 @@ pgroup:add('test_delete_secondary_idx', function(g)
     t.assert_equals(result, nil)
 end)
 
+pgroup:add('test_update_sharding_keys_cache', function(g)
+    local space_name = 'customers_name_key'
+    local sharding_key = helpers.update_sharding_keys_cache(g.cluster, space_name)
+    t.assert_equals(sharding_key, {'name'})
+
+    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 = helpers.update_sharding_keys_cache(g.cluster, space_name)
+    t.assert_equals(sharding_key, {'age'})
+
+    -- 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 = helpers.update_sharding_keys_cache(g.cluster, space_name)
+    t.assert_equals(sharding_key, {'name'})
+end)
+
 pgroup:add('test_non_unique_index', function(g)
     local space_name = 'customers_name_key_non_uniq_index'
     local tuple = {6, box.NULL, 'Victor', 58}