Re: [Tarantool-patches] [PATCH v4 6/8] lua/log: use log module settings inside box.cfg

[Oleg Babin <olegrok@tarantool.org>]

Hi! Thanks for your patch! Looks good but I still think that log 
prefixes are redundant. Is it possible to drop them?

E.g. yaml.cfg example (no "yaml_" prefixes):
```
tarantool> require('yaml').cfg
---
- encode_load_metatables: true
   encode_invalid_numbers: true
   encode_use_tostring: false
   decode_max_depth: 128
   encode_number_precision: 14
   encode_sparse_convert: true
   encode_max_depth: 128
   decode_invalid_numbers: true
   encode_sparse_ratio: 2
   encode_invalid_as_nil: false
   encode_sparse_safe: 10
   encode_deep_as_nil: false
   decode_save_metatables: true
...
```

```
tarantool> require('log').cfg
---
- log_format: json
   log_level: 1000
   log_nonblock: false
...
```

On 28/05/2020 13:07, Cyrill Gorcunov wrote:
> Since we're going to implement early setup of
> logging module we need both.
> 
> Part-of #689
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
>   src/box/lua/load_cfg.lua | 21 +++++++++++++++------
>   src/lua/log.lua          | 37 ++++++++++++++++++++++++++++++++++++-
>   2 files changed, 51 insertions(+), 7 deletions(-)
> 
> diff --git a/src/box/lua/load_cfg.lua b/src/box/lua/load_cfg.lua
> index 5d818addf..9aef12840 100644
> --- a/src/box/lua/load_cfg.lua
> +++ b/src/box/lua/load_cfg.lua
> @@ -1,4 +1,6 @@
>   -- load_cfg.lua - internal file
> +--
> +-- vim: ts=4 sw=4 et
>   
>   local log = require('log')
>   local json = require('json')
> @@ -59,10 +61,6 @@ local default_cfg = {
>       vinyl_range_size          = nil, -- set automatically
>       vinyl_page_size           = 8 * 1024,
>       vinyl_bloom_fpr           = 0.05,
> -    log                 = nil,
> -    log_nonblock        = nil,
> -    log_level           = 5,
> -    log_format          = "plain",
>       io_collect_interval = nil,
>       readahead           = 16320,
>       snap_io_rate_limit  = nil, -- no limit
> @@ -233,8 +231,8 @@ end
>   local dynamic_cfg = {
>       listen                  = private.cfg_set_listen,
>       replication             = private.cfg_set_replication,
> -    log_level               = private.cfg_set_log_level,
> -    log_format              = private.cfg_set_log_format,
> +    log_level               = log.box_api.set_log_level,
> +    log_format              = log.box_api.set_log_format,
>       io_collect_interval     = private.cfg_set_io_collect_interval,
>       readahead               = private.cfg_set_readahead,
>       too_long_threshold      = private.cfg_set_too_long_threshold,
> @@ -470,6 +468,16 @@ local function apply_default_cfg(cfg, default_cfg)
>       end
>   end
>   
> +local function apply_default_modules_cfg(cfg)
> +    --
> +    -- logging
> +    for k,v in pairs(log.box_api.cfg) do
> +        if cfg[k] == nil then
> +            cfg[k] = v
> +        end
> +    end
> +end
> +
>   -- Return true if two configurations are equivalent.
>   local function compare_cfg(cfg1, cfg2)
>       if type(cfg1) ~= type(cfg2) then
> @@ -554,6 +562,7 @@ local function load_cfg(cfg)
>       cfg = upgrade_cfg(cfg, translate_cfg)
>       cfg = prepare_cfg(cfg, default_cfg, template_cfg, modify_cfg)
>       apply_default_cfg(cfg, default_cfg);
> +    apply_default_modules_cfg(cfg)
>       -- Save new box.cfg
>       box.cfg = cfg
>       if not pcall(private.cfg_check)  then
> diff --git a/src/lua/log.lua b/src/lua/log.lua
> index 4b078d598..ce546f21e 100644
> --- a/src/lua/log.lua
> +++ b/src/lua/log.lua
> @@ -97,6 +97,22 @@ local fmt_str2num = {
>       ["json"]            = ffi.C.SF_JSON,
>   }
>   
> +--
> +-- Default options. The keys are part of
> +-- user API, so change with caution.
> +local default_cfg = {
> +    log             = nil,
> +    log_nonblock    = nil,
> +    log_level       = S_INFO,
> +    log_format      = fmt_num2str[ffi.C.SF_PLAIN],
> +}
> +
> +local log_cfg = setmetatable(default_cfg, {
> +    __newindex = function()
> +        error('log: Attempt to modify a read-only table')
> +    end,
> +})
> +
>   local function say(level, fmt, ...)
>       if ffi.C.log_level < level then
>           -- don't waste cycles on debug.getinfo()
> @@ -146,7 +162,8 @@ local function log_rotate()
>   end
>   
>   local function log_level(level)
> -    return ffi.C.say_set_log_level(level)
> +    ffi.C.say_set_log_level(level)
> +    rawset(log_cfg, 'log_level', level)
>   end
>   
>   local function log_format(name)
> @@ -170,6 +187,7 @@ local function log_format(name)
>       else
>           ffi.C.say_set_log_format(ffi.C.SF_PLAIN)
>       end
> +    rawset(log_cfg, 'log_format', name)
>   end
>   
>   local function log_pid()
> @@ -197,9 +215,26 @@ local log = {
>       pid = log_pid,
>       level = log_level,
>       log_format = log_format,
> +    --
> +    -- Internal API to box module, not for users,
> +    -- names can be changed.
> +    box_api = {
> +        cfg = log_cfg,
> +        set_log_level = function()
> +            log_level(box.cfg.log_level)
> +        end,
> +        set_log_format = function()
> +            log_format(box.cfg.log_format)
> +        end,
> +    },
>   }
>   
>   setmetatable(log, {
> +    __serialize = function(self)
> +        local res = table.copy(self)
> +        res.box_api = nil
> +        return setmetatable(res, {})
> +    end,
>       __index = compat_v16;
>   })
>   
>