drivers: fix task state reported to on_task_change on ttl

In the "ttl tasks" loop of the fifottl and utubettl driver fibers the loop
variable shadowed the 'state' module:

    for _, state in pairs(ttl_states) do
        ...
        task = self:delete(task[i_id]):transform(2, 1, state.DONE)

Inside the loop `state` is a status string, so `state.DONE` indexes a string,
evaluates to nil, and `transform(2, 1, nil)` sets the status field to NULL
instead of DONE. The task passed to the user's on_task_change callback with
the 'ttl' event was therefore malformed.

Rename the loop variable to `task_state`.

Closes #255

Author: bigbes

CHANGELOG.md

@@ -13,6 +13,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 
+- The `on_task_change` callback got an expired task with a `NULL` status
+  instead of `DONE` (`fifottl`, `utubettl`) (#255).
+
 ## [1.5.0] - 2026-07-10
 
 This release introduces tube-level grants for roles (supported by all default

queue/abstract/driver/fifottl.lua

@@ -109,9 +109,9 @@ local function fifottl_fiber_iteration(self, processed)
     end
 
     -- ttl tasks
-    for _, state in pairs(ttl_states) do
-        task = self.space.index.watch:min{ state }
-        if task ~= nil and task[i_status] == state then
+    for _, task_state in pairs(ttl_states) do
+        task = self.space.index.watch:min{ task_state }
+        if task ~= nil and task[i_status] == task_state then
             if now >= task[i_next_event] then
                 task = self:delete(task[i_id]):transform(2, 1, state.DONE)
                 self:on_task_change(task, 'ttl')

queue/abstract/driver/utubettl.lua

@@ -236,9 +236,9 @@ local function utubettl_fiber_iteration(self, processed)
     end
 
     -- ttl tasks
-    for _, state in pairs(ttl_states) do
-        task = self.space.index.watch:min{ state }
-        if task ~= nil and task[i_status] == state then
+    for _, task_state in pairs(ttl_states) do
+        task = self.space.index.watch:min{ task_state }
+        if task ~= nil and task[i_status] == task_state then
             if now >= task[i_next_event] then
                 task = self:delete(task[i_id]):transform(2, 1, state.DONE)
                 self:on_task_change(task, 'ttl')

t/250-otc-cb-ttl.t

@@ -0,0 +1,62 @@
+#!/usr/bin/env tarantool
+local test = require('tap').test()
+test:plan(2)
+
+local fiber = require('fiber')
+
+local tnt = require('t.tnt')
+tnt.cfg{}
+
+local engine = os.getenv('ENGINE') or 'memtx'
+
+local queue = require('queue')
+local state = require('queue.abstract.state')
+
+-- In the "ttl tasks" loop of the driver fiber the loop variable shadowed the
+-- 'state' module, so `state.DONE` was indexing a string and evaluated to nil.
+-- As a result the task reported to the on_task_change callback had its status
+-- field set to NULL instead of state.DONE.
+local function check_ttl_status(test, tube_name, driver, put_opts)
+    local ttl_task
+
+    local tube = queue.create_tube(tube_name, driver, {
+        engine = engine,
+        ttl    = 0.1,
+        on_task_change = function(task, stats_data)
+            if stats_data == 'ttl' then
+                ttl_task = task
+            end
+        end
+    })
+
+    tube:put({'expired'}, put_opts)
+
+    local deadline = fiber.clock() + 30
+    while ttl_task == nil and fiber.clock() < deadline do
+        fiber.sleep(0.05)
+    end
+
+    if ttl_task == nil then
+        test:fail('on_task_change is called with the "ttl" event')
+        test:fail('the expired task is reported in the DONE state')
+        return
+    end
+
+    test:ok(true, 'on_task_change is called with the "ttl" event')
+    test:is(ttl_task[2], state.DONE,
+        'the expired task is reported in the DONE state')
+end
+
+test:test('fifottl', function(test)
+    test:plan(2)
+    check_ttl_status(test, 'otc_ttl_fifottl', 'fifottl', {})
+end)
+
+test:test('utubettl', function(test)
+    test:plan(2)
+    check_ttl_status(test, 'otc_ttl_utubettl', 'utubettl', {utube = 'u'})
+end)
+
+tnt.finish()
+os.exit(test:check() and 0 or 1)
+-- vim: set ft=lua :