[tarantool-patches] Re: [PATCH] tarantoolctl: remove metatable assumptions in start()

[Roman Khabibov]

> On Apr 15, 2019, at 1:41 AM, Alexander Turenko <alexander.turenko at tarantool.org> wrote:
> 
> The code is okay, but I would clarify the commit message a bit.
> 
>>>> 
>>>>  There was assumpted uninitialized metamethods of box.cfg{} if user
>>>>  did't call it in his instance.
>>> 
>>> This sentence raises more questions then give answers. What is
>>> 'uninitialized metamethods'? Whether 'of box.cfg{}' means result of the
>>> call or a new value of the 'cfg' field of the 'box' table?
>>> 
>>> Also I doubt 'There was assumpted' is valid phrase.
>> 
>>   tarantoolctl: raise error when box.cfg isn't called
>> 
>>   There was no check whether box.cfg{} was initialized in an
>>   instance. If so, an error should be raised.
> 
> 'box' can be initialized (it is a module), 'box.cfg' can be called, but
> we usually use parentheses to mark a name as a function, so 'box.cfg()'
> can be called. Technically 'box.cfg{} was initialized' is not correct.
> 
> 'If so' here point to the positive case (when called).
> 
> Let me propose wording that will satisfy me:
> 
>> Added a check whether box.cfg() is called within an instance file. If
>> box.cfg() is missed, point a user the reason of a fail explicitly.
>> 
>> Before this commit the error was look so:
>> 
>> /usr/bin/tarantoolctl:541: attempt to index a nil value
> 
> Also don't forget to add 'Fixes #xxxx' clause to the end of the commit
> message.
Done.

commit 7aba9a68b1139738fc3da1bfa39c490f3afdfc5e
Author: Roman Khabibov <roman.habibov at tarantool.org>
Date:   Mon Mar 25 20:52:05 2019 +0300

   tarantoolctl: raise error when box.cfg isn't called

   Added a check whether box.cfg() is called within an instance
   file. If box.cfg() is missed, point a user the reason of a
   fail explicitly.

   Before this commit the error was look so:

   /usr/bin/tarantoolctl:541: attempt to index a nil value

   Closes #3953

diff --git a/extra/dist/tarantoolctl.in b/extra/dist/tarantoolctl.in
index 47fcf895f..37ded5333 100755
--- a/extra/dist/tarantoolctl.in
+++ b/extra/dist/tarantoolctl.in
@@ -547,8 +547,13 @@ local function start()
        end
        os.exit(1)
    end
-    local old_call = getmetatable(box.cfg).__call
-    getmetatable(box.cfg).__call = function(old_cfg, cfg)
+    local box_cfg_mt = getmetatable(box.cfg)
+    if box_cfg_mt == nil then
+        log.error('box.cfg() is not called in an instance file')
+        os.exit(1)
+    end
+    local old_call = box_cfg_mt.__call
+    box_cfg_mt.__call = function(old_cfg, cfg)
        if old_cfg.pid_file ~= nil and cfg ~= nil and cfg.pid_file ~= nil then
            cfg.pid_file = old_cfg.pid_file
        end
diff --git a/test/app-tap/tarantoolctl.test.lua b/test/app-tap/tarantoolctl.test.lua
index db046e03f..7d7c63371 100755
--- a/test/app-tap/tarantoolctl.test.lua
+++ b/test/app-tap/tarantoolctl.test.lua
@@ -163,12 +163,14 @@ test:plan(7)
-- must be stopped afterwards
do
    local dir = fio.tempdir()
-    local code = [[ box.cfg{memtx_memory = 104857600} ]]
-    create_script(dir, 'script.lua', code)
+    create_script(dir, 'script.lua', [[ box.cfg{memtx_memory = 104857600} ]])
+    create_script(dir, 'no_box_cfg.lua', [[ print('Hi!') ]])

    local status, err = pcall(function()
        test:test("basic test", function(test_i)
-            test_i:plan(16)
+            test_i:plan(18)
+            check_ok(test_i, dir, 'start', 'no_box_cfg', 1, nil, "Starting instance",
+                     "box.cfg() is not called in an instance file")
            check_ok(test_i, dir, 'start',  'script', 0, nil, "Starting instance")
            tctl_wait_start(dir, 'script')
            check_ok(test_i, dir, 'status', 'script', 0, nil, "is running")