internal: master presence timout for get space

Added timeout condition for the validation of master presence in
replicaset and for the master connection to the `utils.get_space`
method.

Closes #95

Author: GRISHNOV

CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
 
 ### Added
+* Added timeout condition for the validation of master presence in 
+  replicaset and for the master connection to the `utils.get_space` 
+  method (#95).
 
 ### Changed
 

crud/common/const.lua

@@ -5,6 +5,8 @@ const.RELOAD_SCHEMA_TIMEOUT = 3 -- 3 seconds
 const.FETCH_SHARDING_METADATA_TIMEOUT = 3 -- 3 seconds
 const.SHARDING_RELOAD_RETRIES_NUM = 1
 
+const.GET_SPACE_TIMEOUT = 3 -- 3 seconds
+
 const.NEED_SCHEMA_RELOAD   = 0x0001000
 const.NEED_SHARDING_RELOAD = 0x0001001
 

crud/common/utils.lua

@@ -22,6 +22,7 @@ local NotInitializedError = errors.new_class('NotInitialized')
 local StorageInfoError = errors.new_class('StorageInfoError')
 local VshardRouterError = errors.new_class('VshardRouterError', {capture_stack = false})
 local fiber_clock = require('fiber').clock
+local fiber = require('fiber')
 
 local utils = {}
 
@@ -105,19 +106,44 @@ function utils.get_space(space_name, replicasets)
             'perhaps other instances are unavailable or you have configured only the router')
     end
 
-    if replicaset.master == nil then
-        local error_msg = string.format(
-            'The master was not found in replicaset %s, ' ..
-            'check status of the master and repeat the operation later',
-             replicaset.uuid)
-        return nil, GetSpaceError:new(error_msg)
-    end
+    if replicaset.master == nil or replicaset.master.conn.error ~= nil then
+        -- Try to get master again with timeout.
+        local deadline = fiber_clock() + const.GET_SPACE_TIMEOUT
+        local vshard_router, err = utils.get_vshard_router_instance()
+        if err ~= nil then
+            return nil, GetSpaceError:new(err)
+        end
+        while true do
+            ::continue::
+            fiber.yield()
+            replicasets = vshard_router:routeall()
+            replicaset = select(2, next(replicasets))
+
+            if replicaset.master ~= nil and replicaset.master.conn.error ~= nil then
+                if fiber_clock() < deadline then
+                    -- Try to get the master again, the connection to it may be established.
+                    goto continue
+                else
+                    local error_msg = string.format(
+                        'The connection to the master of replicaset %s is not valid: %s',
+                         replicaset.uuid, replicaset.master.conn.error)
+                    return nil, GetSpaceError:new(error_msg)
+                end
+            end
+
+            if replicaset.master == nil and fiber_clock() >= deadline then
+                local error_msg = string.format(
+                    'The master was not found in replicaset %s, ' ..
+                    'check status of the master and repeat the operation later',
+                     replicaset.uuid)
+                return nil, GetSpaceError:new(error_msg)
+            end
 
-    if replicaset.master.conn.error ~= nil then
-        local error_msg = string.format(
-            'The connection to the master of replicaset %s is not valid: %s',
-             replicaset.uuid, replicaset.master.conn.error)
-        return nil, GetSpaceError:new(error_msg)
+            if replicaset.master ~= nil and replicaset.master.conn.error == nil then
+                -- Break if there is master and connection to it is established.
+                break
+            end
+        end
     end
     local space = replicaset.master.conn.space[space_name]