Make select error more informative

Report "crud is not initialized" error if storage functions
are not defined.
Before this patch, select error description does not give
any clues about possible causes of undefined storage functions.

Part of #229

Author: psergee

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 
 ### Changed
+* Make select error description more informative in case
+  of disabled/uninit storage.
 
 ### Fixed
 

crud/common/call.lua

@@ -7,7 +7,6 @@ local sharding_utils = require('crud.common.sharding.utils')
 local fiber_clock = require('fiber').clock
 
 local CallError = errors.new_class('CallError')
-local NotInitializedError = errors.new_class('NotInitialized')
 
 local call = {}
 
@@ -46,16 +45,6 @@ local function wrap_vshard_err(err, func_name, replicaset_uuid, bucket_id)
         return errors.wrap(err)
     end
 
-    if err.type == 'ClientError' and type(err.message) == 'string' then
-        if err.message == string.format("Procedure '%s' is not defined", func_name) then
-            if func_name:startswith('_crud.') then
-                err = NotInitializedError:new("crud isn't initialized on replicaset: %q", replicaset_uuid)
-            else
-                err = NotInitializedError:new("Function %s is not registered", func_name)
-            end
-        end
-    end
-
     if replicaset_uuid == nil then
         local replicaset, _ = vshard.router.route(bucket_id)
         if replicaset == nil then
@@ -67,6 +56,7 @@ local function wrap_vshard_err(err, func_name, replicaset_uuid, bucket_id)
         replicaset_uuid = replicaset.uuid
     end
 
+    err = utils.update_storage_call_error_description(err, func_name, replicaset_uuid)
     err = errors.wrap(err)
 
     return CallError:new(utils.format_replicaset_error(

crud/common/utils.lua

@@ -14,6 +14,7 @@ local ParseOperationsError = errors.new_class('ParseOperationsError', {capture_s
 local ShardingError = errors.new_class('ShardingError', {capture_stack = false})
 local GetSpaceFormatError = errors.new_class('GetSpaceFormatError', {capture_stack = false})
 local FilterFieldsError = errors.new_class('FilterFieldsError', {capture_stack = false})
+local NotInitializedError = errors.new_class('NotInitialized')
 
 local utils = {}
 
@@ -692,4 +693,22 @@ function utils.check_name_isident(name)
     return true
 end
 
+function utils.update_storage_call_error_description(err, func_name, replicaset_uuid)
+    if err == nil then
+        return nil
+    end
+
+    if err.type == 'ClientError' and type(err.message) == 'string' then
+        if err.message == string.format("Procedure '%s' is not defined", func_name) then
+            if func_name:startswith('_crud.') then
+                err = NotInitializedError:new("crud isn't initialized on replicaset: %q",
+                    replicaset_uuid or "Unknown")
+            else
+                err = NotInitializedError:new("Function %s is not registered", func_name)
+            end
+        end
+    end
+    return err
+end
+
 return utils

crud/select/merger.lua

@@ -11,6 +11,7 @@ local merger_lib = compat.require('tuple.merger', 'merger')
 
 local Keydef = require('crud.compare.keydef')
 local stats = require('crud.stats')
+local utils = require("crud.common.utils")
 
 local function bswap_u16(num)
     return bit.rshift(bit.bswap(tonumber(num)), 16)
@@ -113,7 +114,8 @@ local function fetch_chunk(context, state)
     -- Wait for requested data.
     local res, err = future:wait_result(timeout)
     if res == nil then
-        error(err)
+        local wrapped_err = errors.wrap(utils.update_storage_call_error_description(err, func_name, replicaset.uuid))
+        error(wrapped_err)
     end
 
     -- Decode metainfo, leave data to be processed by the merger.