Re: [Tarantool-patches] [PATCH v3 05/10] lua/log: put string constants to map

[Oleg Babin <olegrok@tarantool.org>]

Hi! Thanks for your patch! See two comments below.

On 27/05/2020 14:14, Cyrill Gorcunov wrote:
> This allows us to reuse them instead of copying
> opencoded constants. They are highly bound to
> ones compiled into the C code.
> 
> Part-of #689
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
>   src/lua/log.lua | 33 +++++++++++++++++++++++++++------
>   1 file changed, 27 insertions(+), 6 deletions(-)
> 
> diff --git a/src/lua/log.lua b/src/lua/log.lua
> index 9830b0886..3fceb1d0e 100644
> --- a/src/lua/log.lua
> +++ b/src/lua/log.lua
> @@ -83,6 +83,20 @@ local special_fields = {
>       "error_msg"
>   }
>   
> +--
> +-- Map format number to string.
> +local fmt_num2str = {
> +    [ffi.C.SF_PLAIN]    = "plain",
> +    [ffi.C.SF_JSON]     = "json",
> +}
> +
> +--
> +-- Map format string to number.
> +local fmt_str2num = {
> +    ["plain"]           = ffi.C.SF_PLAIN,
> +    ["json"]            = ffi.C.SF_JSON,
> +}
> +
>   local function say(level, fmt, ...)
>       if ffi.C.log_level < level then
>           -- don't waste cycles on debug.getinfo()
> @@ -104,7 +118,7 @@ local function say(level, fmt, ...)
>           fmt = json.encode(fmt)
>           if ffi.C.log_format == ffi.C.SF_JSON then
>               -- indicate that message is already encoded in JSON
> -            format = "json"
> +            format = fmt_num2str[ffi.C.SF_JSON]
>           end
>       elseif type_fmt ~= 'string' then
>           fmt = tostring(fmt)
> @@ -135,16 +149,23 @@ local function log_level(level)
>       return ffi.C.say_set_log_level(level)
>   end
>   
> -local function log_format(format_name)
> -    if format_name == "json" then
> +local function log_format(name)
> +    if not fmt_str2num[name] then
> +        local keyset = {}
> +        for k,_ in pairs(fmt_str2num) do

nit: I think `_` could be omitted.

> +            keyset[#keyset+1] = k

nit: To follow Tarantool lua style guide spaces around `+` should be 
added (https://www.tarantool.io/en/doc/2.2/dev_guide/lua_style_guide)
> +        end
> +        local m = "log_format: expected %s"
> +        error(m:format(table.concat(keyset,',')))
> +    end
> +
> +    if fmt_str2num[name] == ffi.C.SF_JSON then
>           if ffi.C.log_type() == ffi.C.SAY_LOGGER_SYSLOG then
>               error("log_format: 'json' can't be used with syslog logger")
>           end
>           ffi.C.say_set_log_format(ffi.C.SF_JSON)
> -    elseif format_name == "plain" then
> -        ffi.C.say_set_log_format(ffi.C.SF_PLAIN)
>       else
> -        error("log_format: expected 'json' or 'plain'")
> +        ffi.C.say_set_log_format(ffi.C.SF_PLAIN)
>       end
>   end
>   
>