api: fix INIT state stuck

Sometimes, instance could enter the queue initialization
while still in the orphan mode. This resulted in "lazy
start". But Tarantool does not call `box.cfg {}` after
leaving orphan mode, so queue was stuck in the `INIT` state.

Now we wait in the background for all orphan instances.
It is similar to lazy init for read-only instances.

Note that this fix works only for Tarantool versions >= 2.10.0.
This is because of using watchers.

Closes #226

Author: DerekBum

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- Stuck in `INIT` state if instance failed to leave `orphan` mode in time (#226).
+  This fix works only for Tarantool versions >= 2.10.0.
+
 ## [1.3.3] - 2023-09-13
 
 ### Fixed

queue/init.lua

@@ -1,5 +1,8 @@
+local fiber = require('fiber')
+
 local abstract = require('queue.abstract')
 local queue_state = require('queue.abstract.queue_state')
+local qc = require('queue.compat')
 local queue = nil
 
 -- load all core drivers
@@ -11,6 +14,10 @@ local core_drivers = {
     limfifottl  = require('queue.abstract.driver.limfifottl')
 }
 
+-- since:
+-- https://github.com/locker/tarantool/commit/8cf5151cb4f05cee3fd0ea831add2b3187a01fe4
+local watchers_supported = qc.check_version({2, 10, 0})
+
 local function register_driver(driver_name, tube_ctr)
     if type(tube_ctr.create_space) ~= 'function' or
         type(tube_ctr.new) ~= 'function' then
@@ -62,6 +69,19 @@ local orig_call = nil
 
 local wrapper_impl
 
+local function orphan_waiter()
+    local wait_cond = fiber.cond()
+    local w = box.watch('box.status', function(_, new_status)
+        fiber.yield()
+        if new_status.status ~= 'orphan' then
+            wait_cond:signal()
+        end
+    end)
+    wait_cond:wait()
+    w:unregister()
+    return wrapper_impl()
+end
+
 local function cfg_wrapper(...)
     box.cfg = orig_cfg
     return wrapper_impl(...)
@@ -79,10 +99,15 @@ local function wrap_box_cfg()
         orig_cfg = box.cfg
         box.cfg = cfg_wrapper
     elseif type(box.cfg) == 'table' then
-        -- box.cfg after the first box.cfg call
-        local cfg_mt = getmetatable(box.cfg)
-        orig_call = cfg_mt.__call
-        cfg_mt.__call = cfg_call_wrapper
+        if watchers_supported and box.info.ro_reason == 'orphan' then
+            -- Wait for the orphan instance.
+            fiber.new(orphan_waiter)
+        else
+            -- box.cfg after the first box.cfg call
+            local cfg_mt = getmetatable(box.cfg)
+            orig_call = cfg_mt.__call
+            cfg_mt.__call = cfg_call_wrapper
+        end
     else
         error('The box.cfg type is unexpected: ' .. type(box.cfg))
     end