ddl: deprecate manual sharding schema reload

Since sharding schema reloads must be processed automatically after this
patchset, there shouldn't be usual cases where user need to reload
sharding info manually. Thus methods for manual sharding schema reload
are deprecated and will be removed in future releases.

Follows up #212

Author: DifferentialOrange

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Changed
 * Optimize select with known bucket_id (#234).
+* Deprecate manual sharding schema reload (#212).
 
 ### Fixed
 * Fix processing storage error for tuple-merger implementation of

README.md

@@ -117,26 +117,11 @@ Table below describe what operations supports custom sharding key:
 
 Current limitations for using custom sharding key:
 
-- It's not possible to update sharding keys automatically when schema is
-  updated on storages, see
-  [#212](https://github.com/tarantool/crud/issues/212). However it is possible
-  to do it manually with `require('crud.common.sharding_key').update_cache()`
-  (this function updates both caches: sharding key cache and sharding function
-  cache, but returned value is sharding key from cache).
 - No support of JSON path for sharding key, see
   [#219](https://github.com/tarantool/crud/issues/219).
 - `primary_index_fieldno_map` is not cached, see
   [#243](https://github.com/tarantool/crud/issues/243).
 
-Current limitations for using custom sharding functions:
-
-- It's not possible to update sharding functions automatically when schema is
-  updated on storages, see
-  [#212](https://github.com/tarantool/crud/issues/212). However it is possible
-  to do it manually with `require('crud.common.sharding_func').update_cache()`
-  (this function updates both caches: sharding key cache and sharding function
-  cache, but returned value is sharding function from cache).
-
 ### Insert
 
 ```lua

crud/common/sharding_func.lua

@@ -1,3 +1,5 @@
+local log = require('log')
+
 local sharding_metadata_module = require('crud.common.sharding.sharding_metadata')
 
 local sharding_func_cache = {}
@@ -9,6 +11,8 @@ local sharding_func_cache = {}
 -- This method provides similar behavior for
 -- sharding function cache.
 function sharding_func_cache.update_cache(space_name)
+    log.warn("require('crud.common.sharding_func').update_cache()" ..
+             "is deprecated and will be removed in future releases")
     return sharding_metadata_module.update_sharding_func_cache(space_name)
 end
 

crud/common/sharding_key.lua

@@ -1,3 +1,5 @@
+local log = require('log')
+
 local sharding_metadata_module = require('crud.common.sharding.sharding_metadata')
 
 local sharding_key_cache = {}
@@ -7,6 +9,8 @@ local sharding_key_cache = {}
 -- for updating sharding key cache in their
 -- projects like `require('crud.common.sharding_key').update_cache()`
 function sharding_key_cache.update_cache(space_name)
+    log.warn("require('crud.common.sharding_key').update_cache()" ..
+             "is deprecated and will be removed in future releases")
     return sharding_metadata_module.update_sharding_key_cache(space_name)
 end