Separate common sharding metadata methods from sharding key methods

It would be more efficient to get sharding keys and
sharding functions from storage in one `fetch_on_storage`
function call. So, this function is common for sharding
keys and sharding functions support. As well as functions
for fetching on router. These methods are introduced
in `sharding_metadata` module. Methods for working
with sharding key structure are introduced in
sharding key module.

Part of #237

crud/common/const.lua

@@ -2,6 +2,6 @@ local const = {}
 
 const.RELOAD_RETRIES_NUM = 1
 const.RELOAD_SCHEMA_TIMEOUT = 3 -- 3 seconds
-const.FETCH_SHARDING_KEY_TIMEOUT = 3 -- 3 seconds
+const.FETCH_SHARDING_METADATA_TIMEOUT = 3 -- 3 seconds
 
 return const

crud/common/sharding/init.lua

@@ -22,7 +22,7 @@ function sharding.tuple_get_bucket_id(tuple, space, specified_bucket_id)
     end
 
     local sharding_index_parts = space.index[0].parts
-    local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_on_router(space.name)
+    local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_sharding_key_on_router(space.name)
     if err ~= nil then
         return nil, err
     end

crud/common/sharding/sharding_key.lua

@@ -75,15 +75,9 @@ end
 
 -- Extract sharding key from pk.
 -- Returns a table with sharding key or pair of nil and error.
-function sharding_key_module.extract_from_pk(space_name, primary_index_parts, primary_key, timeout)
-    dev_checks('string', 'table', '?', '?number')
-
-    local sharding_key_as_index_obj, err = require(
-                                           'crud.common.sharding.sharding_metadata'
-                                           ).fetch_on_router(space_name, timeout)
-    if err ~= nil then
-        return nil, err
-    end
+function sharding_key_module.extract_from_pk(space_name, sharding_key_as_index_obj, primary_index_parts, primary_key)
+    dev_checks('string', '?table', 'table', '?')
+
     if sharding_key_as_index_obj == nil then
         return primary_key
     end
@@ -102,6 +96,24 @@ function sharding_key_module.extract_from_pk(space_name, primary_index_parts, pr
     return extract_from_index(primary_key, primary_index_parts, sharding_key_as_index_obj)
 end
 
+function sharding_key_module.construct_as_index_obj_cache(metadata_map)
+    dev_checks('table')
+
+    cache.sharding_key_as_index_obj_map = {}
+    for space_name, metadata in pairs(metadata_map) do
+        if metadata.sharding_key_def ~= nil then
+            local sharding_key_as_index_obj, err = as_index_object(space_name,
+                                                                   metadata.space_format,
+                                                                   metadata.sharding_key_def)
+            if err ~= nil then
+                return err
+            end
+
+            cache.sharding_key_as_index_obj_map[space_name] = sharding_key_as_index_obj
+        end
+    end
+end
+
 sharding_key_module.internal = {
     as_index_object = as_index_object,
     extract_from_index = extract_from_index,

crud/common/sharding/sharding_metadata.lua

@@ -5,12 +5,13 @@ local call = require('crud.common.call')
 local const = require('crud.common.const')
 local dev_checks = require('crud.common.dev_checks')
 local cache = require('crud.common.sharding.sharding_metadata_cache')
+local sharding_key = require('crud.common.sharding.sharding_key')
 
-local FetchShardingKeyError = errors.new_class('FetchShardingKeyError', {capture_stack = false})
+local FetchShardingMetadataError = errors.new_class('FetchShardingMetadataError', {capture_stack = false})
 
 local FETCH_FUNC_NAME = '_crud.fetch_on_storage'
 
-local sharding_key_module = {}
+local sharding_metadata_module = {}
 
 -- Function decorator that is used to prevent _fetch_on_router() from being
 -- called concurrently by different fibers.
@@ -25,8 +26,8 @@ local function locked(f)
         -- first reason, I'm not sure we need to disclose to users such details
         -- like problems with synchronization objects.
         if not ok then
-            return FetchShardingKeyError:new(
-                "Timeout for fetching sharding key is exceeded")
+            return FetchShardingMetadataError:new(
+                "Timeout for fetching sharding metadata is exceeded")
         end
         local timeout = timeout_deadline - fiber.clock()
         local status, err = pcall(f, timeout, ...)
@@ -39,7 +40,7 @@ end
 
 -- Return a map with metadata or nil when space box.space._ddl_sharding_key is
 -- not available on storage.
-function sharding_key_module.fetch_on_storage()
+function sharding_metadata_module.fetch_on_storage()
     local sharding_key_space = box.space._ddl_sharding_key
     if sharding_key_space == nil then
         return nil
@@ -67,10 +68,10 @@ end
 -- a sharding metadata by a single one, other fibers will wait while
 -- cache.fetch_lock become unlocked during timeout passed to
 -- _fetch_on_router().
-local _fetch_on_router = locked(function(timeout)
-    dev_checks('number')
+local _fetch_on_router = locked(function(timeout, space_name, metadata_map_name)
+    dev_checks('number', 'string', 'string')
 
-    if cache.sharding_key_as_index_obj_map ~= nil then
+    if cache[metadata_map_name] ~= nil then
         return
     end
 
@@ -81,21 +82,13 @@ local _fetch_on_router = locked(function(timeout)
         return err
     end
     if metadata_map == nil then
-        cache.sharding_key_as_index_obj_map = {}
+        cache[cache.SHARDING_KEY_MAP_NAME] = {}
         return
     end
 
-    cache.sharding_key_as_index_obj_map = {}
-    for space_name, metadata in pairs(metadata_map) do
-        local sharding_key_as_index_obj, err = require(
-                                               'crud.common.sharding.sharding_key'
-                                               ).internal.as_index_object(space_name,
-                                                                          metadata.space_format,
-                                                                          metadata.sharding_key_def)
-        if err ~= nil then
-            return err
-        end
-        cache.sharding_key_as_index_obj_map[space_name] = sharding_key_as_index_obj
+    local err = sharding_key.construct_as_index_obj_cache(metadata_map, space_name)
+    if err ~= nil then
+        return err
     end
 end)
 
@@ -108,37 +101,38 @@ end)
 --  that nil without error is a successfull return value.
 --  - nil and error, when something goes wrong on fetching attempt.
 --
-function sharding_key_module.fetch_on_router(space_name, timeout)
-    dev_checks('string', '?number')
-
-    if cache.sharding_key_as_index_obj_map ~= nil then
-        return cache.sharding_key_as_index_obj_map[space_name]
+local function fetch_on_router(space_name, metadata_map_name, timeout)
+    if cache[metadata_map_name] ~= nil then
+        return cache[metadata_map_name][space_name]
     end
 
-    local timeout = timeout or const.FETCH_SHARDING_KEY_TIMEOUT
-    local err = _fetch_on_router(timeout)
+    local timeout = timeout or const.FETCH_SHARDING_METADATA_TIMEOUT
+    local err = _fetch_on_router(timeout, space_name, metadata_map_name)
     if err ~= nil then
-        if cache.sharding_key_as_index_obj_map ~= nil then
-            return cache.sharding_key_as_index_obj_map[space_name]
-        end
         return nil, err
     end
 
-    if cache.sharding_key_as_index_obj_map ~= nil then
-        return cache.sharding_key_as_index_obj_map[space_name]
+    if cache[metadata_map_name] ~= nil then
+        return cache[metadata_map_name][space_name]
     end
 
-    return nil, FetchShardingKeyError:new(
+    return nil, FetchShardingMetadataError:new(
         "Fetching sharding key for space '%s' is failed", space_name)
 end
 
-function sharding_key_module.update_cache(space_name)
+function sharding_metadata_module.fetch_sharding_key_on_router(space_name, timeout)
+    dev_checks('string', '?number')
+
+    return fetch_on_router(space_name, cache.SHARDING_KEY_MAP_NAME, timeout)
+end
+
+function sharding_metadata_module.update_sharding_key_cache(space_name)
     cache.drop_caches()
-    return sharding_key_module.fetch_on_router(space_name)
+    return sharding_metadata_module.fetch_sharding_key_on_router(space_name)
 end
 
-function sharding_key_module.init()
-   _G._crud.fetch_on_storage = sharding_key_module.fetch_on_storage
+function sharding_metadata_module.init()
+   _G._crud.fetch_on_storage = sharding_metadata_module.fetch_on_storage
 end
 
-return sharding_key_module
+return sharding_metadata_module

crud/common/sharding/sharding_metadata_cache.lua

@@ -1,18 +1,19 @@
 local fiber = require('fiber')
 
-local sharding_key_cache = {}
+local sharding_metadata_cache = {}
 
-sharding_key_cache.sharding_key_as_index_obj_map = nil
-sharding_key_cache.fetch_lock = fiber.channel(1)
-sharding_key_cache.is_part_of_pk = {}
+sharding_metadata_cache.SHARDING_KEY_MAP_NAME = "sharding_key_as_index_obj_map"
+sharding_metadata_cache[sharding_metadata_cache.SHARDING_KEY_MAP_NAME] = nil
+sharding_metadata_cache.fetch_lock = fiber.channel(1)
+sharding_metadata_cache.is_part_of_pk = {}
 
-function sharding_key_cache.drop_caches()
-    sharding_key_cache.sharding_key_as_index_obj_map = nil
-    if sharding_key_cache.fetch_lock ~= nil then
-        sharding_key_cache.fetch_lock:close()
+function sharding_metadata_cache.drop_caches()
+    sharding_metadata_cache[sharding_metadata_cache.SHARDING_KEY_MAP_NAME] = nil
+    if sharding_metadata_cache.fetch_lock ~= nil then
+        sharding_metadata_cache.fetch_lock:close()
     end
-    sharding_key_cache.fetch_lock = fiber.channel(1)
-    sharding_key_cache.is_part_of_pk = {}
+    sharding_metadata_cache.fetch_lock = fiber.channel(1)
+    sharding_metadata_cache.is_part_of_pk = {}
 end
 
-return sharding_key_cache
+return sharding_metadata_cache

crud/common/sharding_key.lua

@@ -0,0 +1,9 @@
+local sharding_metadata_module = require('crud.common.sharding.sharding_metadata')
+
+local sharding_key_cache = {}
+
+function sharding_key_cache.update_cache(space_name)
+    return sharding_metadata_module.update_sharding_key_cache(space_name)
+end
+
+return sharding_key_cache

crud/delete.lua

@@ -6,6 +6,7 @@ local call = require('crud.common.call')
 local utils = require('crud.common.utils')
 local sharding = require('crud.common.sharding')
 local sharding_key_module = require('crud.common.sharding.sharding_key')
+local sharding_metadata_module = require('crud.common.sharding.sharding_metadata')
 local dev_checks = require('crud.common.dev_checks')
 local schema = require('crud.common.schema')
 
@@ -58,9 +59,16 @@ local function call_delete_on_router(space_name, key, opts)
 
     local sharding_key = key
     if opts.bucket_id == nil then
-        local err
         local primary_index_parts = space.index[0].parts
-        sharding_key, err = sharding_key_module.extract_from_pk(space_name, primary_index_parts, key, opts.timeout)
+
+        local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_sharding_key_on_router(space_name)
+        if err ~= nil then
+            return nil, err
+        end
+
+        sharding_key, err = sharding_key_module.extract_from_pk(space_name,
+                                                                sharding_key_as_index_obj,
+                                                                primary_index_parts, key)
         if err ~= nil then
             return nil, err
         end

crud/get.lua

@@ -6,6 +6,7 @@ local call = require('crud.common.call')
 local utils = require('crud.common.utils')
 local sharding = require('crud.common.sharding')
 local sharding_key_module = require('crud.common.sharding.sharding_key')
+local sharding_metadata_module = require('crud.common.sharding.sharding_metadata')
 local dev_checks = require('crud.common.dev_checks')
 local schema = require('crud.common.schema')
 
@@ -61,9 +62,16 @@ local function call_get_on_router(space_name, key, opts)
 
     local sharding_key = key
     if opts.bucket_id == nil then
-        local err
         local primary_index_parts = space.index[0].parts
-        sharding_key, err = sharding_key_module.extract_from_pk(space_name, primary_index_parts, key, opts.timeout)
+
+        local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_sharding_key_on_router(space_name)
+        if err ~= nil then
+            return nil, err
+        end
+
+        sharding_key, err = sharding_key_module.extract_from_pk(space_name,
+                                                                sharding_key_as_index_obj,
+                                                                primary_index_parts, key)
         if err ~= nil then
             return nil, err
         end

crud/select/compat/select.lua

@@ -51,7 +51,7 @@ local function build_select_iterator(space_name, user_conditions, opts)
         return nil, SelectError:new("Space %q doesn't exist", space_name), true
     end
     local space_format = space:format()
-    local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_on_router(space_name)
+    local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_sharding_key_on_router(space_name)
     if err ~= nil then
         return nil, err
     end

crud/select/compat/select_old.lua

@@ -103,7 +103,7 @@ local function build_select_iterator(space_name, user_conditions, opts)
         return nil, SelectError:new("Space %q doesn't exist", space_name), true
     end
     local space_format = space:format()
-    local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_on_router(space_name)
+    local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_sharding_key_on_router(space_name)
     if err ~= nil then
         return nil, err
     end

crud/update.lua

@@ -6,6 +6,7 @@ local call = require('crud.common.call')
 local utils = require('crud.common.utils')
 local sharding = require('crud.common.sharding')
 local sharding_key_module = require('crud.common.sharding.sharding_key')
+local sharding_metadata_module = require('crud.common.sharding.sharding_metadata')
 local dev_checks = require('crud.common.dev_checks')
 local schema = require('crud.common.schema')
 
@@ -86,9 +87,16 @@ local function call_update_on_router(space_name, key, user_operations, opts)
 
     local sharding_key = key
     if opts.bucket_id == nil then
-        local err
         local primary_index_parts = space.index[0].parts
-        sharding_key, err = sharding_key_module.extract_from_pk(space_name, primary_index_parts, key, opts.timeout)
+
+        local sharding_key_as_index_obj, err = sharding_metadata_module.fetch_sharding_key_on_router(space_name)
+        if err ~= nil then
+            return nil, err
+        end
+
+        sharding_key, err = sharding_key_module.extract_from_pk(space_name,
+                                                                sharding_key_as_index_obj,
+                                                                primary_index_parts, key)
         if err ~= nil then
             return nil, err
         end

test/helper.lua

@@ -323,12 +323,12 @@ function helpers.tarantool_version_at_least(wanted_major, wanted_minor,
     return true
 end
 
-function helpers.update_cache(cluster, space_name)
+function helpers.update_sharding_key_cache(cluster, space_name)
     return cluster.main_server.net_box:eval([[
-        local sharding_metadata = require('crud.common.sharding.sharding_metadata')
+        local sharding_key = require('crud.common.sharding_key')
 
         local space_name = ...
-        return sharding_metadata.update_cache(space_name)
+        return sharding_key.update_cache(space_name)
     ]], {space_name})
 end
 

test/integration/ddl_sharding_key_test.lua

@@ -657,19 +657,22 @@ 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)
+    local sharding_key_as_index_obj, err = helpers.update_sharding_key_cache(g.cluster, space_name)
+    t.assert_equals(err, nil)
     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)
+    sharding_key_as_index_obj, err = helpers.update_sharding_key_cache(g.cluster, space_name)
+    t.assert_equals(err, nil)
     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)
+    sharding_key_as_index_obj, err = helpers.update_sharding_key_cache(g.cluster, space_name)
+    t.assert_equals(err, nil)
     t.assert_equals(sharding_key_as_index_obj, {parts = {{fieldno = 3}}})
 end