[TNTP-2109] Switch to safe mode on vshard rebalance

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Added
+* Implement "safe" mode to prevent writing data to wrong replicaset when vshard rebalance is in progress.
+* Auto switch to safe mode when rebalance process starts.
+* Manual return to fast mode.
+
 ## [1.6.1] - 19-09-25
 
 ### Added

crud.lua

@@ -23,6 +23,7 @@ local readview = require('crud.readview')
 local schema = require('crud.schema')
 local storage_info = require('crud.storage_info')
 local storage = require('crud.storage')
+local rebalance = require('crud.common.rebalance')
 
 local crud = {}
 
@@ -158,8 +159,23 @@ crud.readview = readview.new
 -- @function schema
 crud.schema = schema.call
 
+crud.rebalance = {}
+
+-- @refer rebalance.router_cache_clear
+-- @function router_cache_clear
+crud.rebalance.router_cache_clear = rebalance.router.cache_clear
+
+-- @refer rebalance.router_cache_length
+-- @function router_cache_length
+crud.rebalance.router_cache_length = rebalance.router.cache_length
+
+-- @refer rebalance.router_cache_last_clear_ts
+-- @function router_cache_last_clear_ts
+crud.rebalance.router_cache_last_clear_ts = rebalance.router.cache_last_clear_ts
+
 function crud.init_router()
-   rawset(_G, 'crud', crud)
+    rawset(_G, 'crud', crud)
+    rebalance.metrics.enable_router_metrics()
 end
 
 function crud.stop_router()

crud/common/call.lua

@@ -4,8 +4,10 @@ local call_cache = require('crud.common.call_cache')
 local dev_checks = require('crud.common.dev_checks')
 local utils = require('crud.common.utils')
 local sharding_utils = require('crud.common.sharding.utils')
-local fiber_clock = require('fiber').clock
+local fiber = require('fiber')
 local const = require('crud.common.const')
+local rebalance = require('crud.common.rebalance')
+local bucket_ref_unref = require('crud.common.sharding.bucket_ref_unref')
 
 local BaseIterator = require('crud.common.map_call_cases.base_iter')
 local BasePostprocessor = require('crud.common.map_call_cases.base_postprocessor')
@@ -15,13 +17,57 @@ local CallError = errors.new_class('CallError')
 local CALL_FUNC_NAME = 'call_on_storage'
 local CRUD_CALL_FUNC_NAME = utils.get_storage_call(CALL_FUNC_NAME)
 
+-- Methods that can continue execution in fast mode when rebalance starts
+local safe_mode_allowed_fast_methods = {
+    CRUD_CALL_FUNC_NAME .. '/fast/' .. utils.get_storage_call('readview_open_on_storage'),
+    CRUD_CALL_FUNC_NAME .. '/fast/' .. utils.get_storage_call('readview_close_on_storage'),
+    CRUD_CALL_FUNC_NAME .. '/fast/' .. utils.get_storage_call('select_readview_on_storage'),
+    CRUD_CALL_FUNC_NAME .. '/fast/' .. utils.get_storage_call('truncate_on_storage'),
+    CRUD_CALL_FUNC_NAME .. '/fast/' .. utils.get_storage_call('len_on_storage'),
+    CRUD_CALL_FUNC_NAME .. '/fast/' .. utils.get_storage_call('count_on_storage'),
+    CRUD_CALL_FUNC_NAME .. '/fast/' .. utils.get_storage_call('get_border_on_storage'),
+}
 
 local call = {}
 
-local function call_on_storage(run_as_user, func_name, ...)
+local function call_on_storage_safe(run_as_user, func_name, ...)
+    fiber.name(CRUD_CALL_FUNC_NAME .. '/safe/' .. func_name)
     return box.session.su(run_as_user, call_cache.func_name_to_func(func_name), ...)
 end
 
+local function call_on_storage_fast(run_as_user, func_name, ...)
+    fiber.name(CRUD_CALL_FUNC_NAME .. '/fast/' .. func_name)
+    return box.session.su(run_as_user, call_cache.func_name_to_func(func_name), ...)
+end
+
+local call_on_storage = rebalance.safe_mode and call_on_storage_safe or call_on_storage_fast
+
+local function safe_mode_enable()
+    call_on_storage = call_on_storage_safe
+
+    for fb_id, fb in pairs(fiber.info()) do
+        if string.find(fb.name, CRUD_CALL_FUNC_NAME .. '/fast/') then
+            local do_kill = true
+            for _, allowed_method in ipairs(safe_mode_allowed_fast_methods) do
+                if fb.name == allowed_method then
+                    do_kill = false
+                    break
+                end
+            end
+            if do_kill then
+                fiber.kill(fb_id)
+            end
+        end
+    end
+end
+
+local function safe_mode_disable()
+    call_on_storage = call_on_storage_fast
+end
+
+rebalance.register_safe_mode_enable_hook(safe_mode_enable)
+rebalance.register_safe_mode_disable_hook(safe_mode_disable)
+
 call.storage_api = {[CALL_FUNC_NAME] = call_on_storage}
 
 function call.get_vshard_call_name(mode, prefer_replica, balance)
@@ -82,7 +128,10 @@ local function wrap_vshard_err(vshard_router, err, func_name, replicaset_id, buc
     ))
 end
 
-local function retry_call_with_master_discovery(replicaset, method, func_name, func_args, call_opts)
+--- Executes a vshard call and retries once after performing recovery actions
+--- like bucket cache reset, destination redirect (for single calls), or master discovery.
+local function call_with_retry_and_recovery(vshard_router,
+    replicaset, method, func_name, func_args, call_opts, is_single_call)
     local func_args_ext = utils.append_array({ box.session.effective_user(), func_name }, func_args)
 
     -- In case cluster was just bootstrapped with auto master discovery,
@@ -93,7 +142,32 @@ local function retry_call_with_master_discovery(replicaset, method, func_name, f
         return resp, err
     end
 
-    if err.name == 'MISSING_MASTER' and replicaset.locate_master ~= nil then
+    -- This is a partial copy of error handling from vshard.router.router_call_impl()
+    -- It is much simpler mostly because bucket_set() can't be accessed from outside vshard.
+    if err.class_name == bucket_ref_unref.BucketRefError.name then
+        local redirect_replicaset
+        if is_single_call and #err.bucket_ref_errs == 1 then
+            local single_err = err.bucket_ref_errs[1]
+            local destination = single_err.vshard_err.destination
+            if destination and vshard_router.replicasets[destination] then
+                redirect_replicaset = vshard_router.replicasets[destination]
+            end
+        end
+
+        for _, bucket_ref_err in pairs(err.bucket_ref_errs) do
+            local bucket_id = bucket_ref_err.bucket_id
+            local vshard_err = bucket_ref_err.vshard_err
+            if vshard_err.name == 'WRONG_BUCKET' or
+                vshard_err.name == 'BUCKET_IS_LOCKED' or
+                vshard_err.name == 'TRANSFER_IS_IN_PROGRESS' then
+                vshard_router:_bucket_reset(bucket_id)
+            end
+        end
+
+        if redirect_replicaset ~= nil then
+            replicaset = redirect_replicaset
+        end
+    elseif err.name == 'MISSING_MASTER' and replicaset.locate_master ~= nil then
         replicaset:locate_master()
     end
 
@@ -147,8 +221,8 @@ function call.map(vshard_router, func_name, func_args, opts)
     while iter:has_next() do
         local args, replicaset, replicaset_id = iter:get()
 
-        local future, err = retry_call_with_master_discovery(replicaset, vshard_call_name,
-            func_name, args, call_opts)
+        local future, err = call_with_retry_and_recovery(vshard_router, replicaset, vshard_call_name,
+            func_name, args, call_opts, false)
 
         if err ~= nil then
             local result_info = {
@@ -170,9 +244,9 @@ function call.map(vshard_router, func_name, func_args, opts)
         futures_by_replicasets[replicaset_id] = future
     end
 
-    local deadline = fiber_clock() + timeout
+    local deadline = fiber.clock() + timeout
     for replicaset_id, future in pairs(futures_by_replicasets) do
-        local wait_timeout = deadline - fiber_clock()
+        local wait_timeout = deadline - fiber.clock()
         if wait_timeout < 0 then
             wait_timeout = 0
         end
@@ -221,9 +295,8 @@ function call.single(vshard_router, bucket_id, func_name, func_args, opts)
     local timeout = opts.timeout or const.DEFAULT_VSHARD_CALL_TIMEOUT
     local request_timeout = opts.mode == 'read' and opts.request_timeout or nil
 
-    local res, err = retry_call_with_master_discovery(replicaset, vshard_call_name,
-        func_name, func_args, {timeout = timeout,
-                               request_timeout = request_timeout})
+    local res, err = call_with_retry_and_recovery(vshard_router, replicaset, vshard_call_name,
+        func_name, func_args, {timeout = timeout, request_timeout = request_timeout}, true)
     if err ~= nil then
         return nil, wrap_vshard_err(vshard_router, err, func_name, nil, bucket_id)
     end
@@ -248,8 +321,8 @@ function call.any(vshard_router, func_name, func_args, opts)
     end
     local replicaset_id, replicaset = next(replicasets)
 
-    local res, err = retry_call_with_master_discovery(replicaset, 'call',
-        func_name, func_args, {timeout = timeout})
+    local res, err = call_with_retry_and_recovery(vshard_router, replicaset, 'call',
+        func_name, func_args, {timeout = timeout}, false)
     if err ~= nil then
         return nil, wrap_vshard_err(vshard_router, err, func_name, replicaset_id)
     end