[Tarantool-patches] [PATCH v8 00/12] lua/log: add an ability to setup logger without box.cfg{}

[Oleg Babin]

Hi! Thanks for your patchset. I've found another example of 
inconsistency between log.cfg and box.cfg:

```
Tarantool 2.5.0-91-ga70675e0e
type 'help' for interactive help
tarantool> box.cfg{log = ''}
2020-06-03 09:57:50.356 [54011] main/103/interactive C> Tarantool 
2.5.0-91-ga70675e0e
2020-06-03 09:57:50.357 [54011] main/103/interactive C> log level 5
...
2020-06-03 09:57:50.408 [54011] main/103/interactive I> set 'log_level' 
configuration option to 5
2020-06-03 09:57:50.408 [54011] main/105/checkpoint_daemon I> scheduled 
next checkpoint for Wed Jun  3 11:45:13 2020
2020-06-03 09:57:50.408 [54011] main/103/interactive I> set 'log_format' 
configuration option to "plain"
```

And

```
Tarantool 2.5.0-91-ga70675e0e
type 'help' for interactive help
tarantool> log = require('log')
---
...

tarantool> log.cfg({log = ''})
SystemError can't open log file: /Users/o.babin/Projects/tarantool/: Is 
a directory
failed to initialize logging subsystem
```

On 03/06/2020 01:18, Cyrill Gorcunov wrote:
> In the series we add an ability to configure logger early
> without calling box.cfg{}. The syntax is the same as
> in box.cfg{} call.
> 
> There was an idea to implement something similar via triggers but
> I think this will require a way more efforts and code redesign,
> so at first lets stick to simplier solution.
> 
> Guys, please don't Ack/LGTM the messages which already have Reviewed-by tags.
> Hopefully this is the last series and code is ready for merging. Though
> I should confess I dont like it much even this "simple" solution looks
> too complex.
> 
> v2 by Oleg:
>   - hide box_api symbols from users
>   - initialize logger via log.cfg() call to look similar to box.cfg
> v3 by Oleg:
>   - add parametesr verification
>   - allow to reconfig via log.cfg() call
> v4 by Oleg:
>   - lua style fixes
>   - extent test (I didn't find a way to test wrong params verification
>     inside tap test, so I did it manually. Still we might extent the
>     test on top of the series).
> v5..v6:
>   - left for internal use
> v7 by Oleg and Leonid:
>   - add bidirectional sync between log and box settings
>   - symbolic names for levels
>   - test extension
>   - reduce ffi usage
> v7 by Oleg:
>   - add verification for `log` being immutable once set via
>     box or log interface
>   - more precise check for dynamic configs
>   - test enhansion for new cases
> 
> branch gorcunov/gh-689-logger-8
> issue https://github.com/tarantool/tarantool/issues/689
> 
> Cyrill Gorcunov (12):
>    core/say: do not reconfig early set up logger
>    core/say: use say_logger_initialized in say_logger_free
>    lua/log: declare say_logger_init and say_logger_initialized
>    lua/log: put string constants to map
>    lua/log: do not allow to set json for boot logger
>    lua/log: declare log as separate variable
>    lua/log: use log module settings inside box.cfg
>    lua/log: allow to configure logging without a box
>    test: logger -- use log module directly
>    log/lua: allow to specify logging level as a string
>    lua/log: use log_cfg instead of ffi's instances
>    test: logger -- consider more cases
> 
>   src/box/lua/load_cfg.lua     |  35 ++++-
>   src/lib/core/say.c           |  15 +-
>   src/lib/core/say.h           |   4 +
>   src/lua/log.lua              | 297 ++++++++++++++++++++++++++++++++---
>   test/app-tap/logger.test.lua | 100 +++++++++++-
>   5 files changed, 418 insertions(+), 33 deletions(-)
>