[Tarantool-patches] [PATCH 6/9] cfg: introduce 'deprecated option' feature

[Vladislav Shpilevoy]

Thanks for the review!

On 10.02.2021 09:59, Oleg Babin wrote:
> Thanks for your patch!
> 
> Is it possible to extend log message to "Option is deprecated and has no effect anymore"?

Good idea. See the diff in this commit.

====================
diff --git a/vshard/cfg.lua b/vshard/cfg.lua
index 28c3400..f7d5dbc 100644
--- a/vshard/cfg.lua
+++ b/vshard/cfg.lua
@@ -61,7 +61,13 @@ local function validate_config(config, template, check_arg)
         local expected_type = template_value.type
         if template_value.is_deprecated then
             if value ~= nil then
-                log.warn('Option "%s" is deprecated', name)
+                local reason = template_value.reason
+                if reason then
+                    reason = '. '..reason
+                else
+                    reason = ''
+                end
+                log.warn('Option "%s" is deprecated'..reason, name)
             end
         elseif value == nil then
             if not template_value.is_optional then
====================

And in the next commit:

====================
diff --git a/vshard/cfg.lua b/vshard/cfg.lua
index f7dd4c1..63d5414 100644
--- a/vshard/cfg.lua
+++ b/vshard/cfg.lua
@@ -252,6 +252,7 @@ local cfg_template = {
     },
     collect_bucket_garbage_interval = {
         name = 'Garbage bucket collect interval', is_deprecated = true,
+        reason = 'Has no effect anymore'
     },
     collect_lua_garbage = {
         type = 'boolean', name = 'Garbage Lua collect necessity',

====================

> Also for some options could be useful: "Option is deprecated, use ... instead" (e.g. for "weights").

With the updated version I can specify any 'reason'. Such as
'has no affect', 'use ... instead', etc.

> Seems it should be more configurable and gives some hint for user to do.
> 
> 
> On 10/02/2021 02:46, Vladislav Shpilevoy wrote:
>> Some options in vshard are going to be eventually deprecated. For
>> instance, 'weigts' will be renamed, 'collect_lua_garbage' may be
> 
> 
> typo: weigts -> weights

Fixed. See the full new patch below.

====================
    cfg: introduce 'deprecated option' feature
    
    Some options in vshard are going to be eventually deprecated. For
    instance, 'weights' will be renamed, 'collect_lua_garbage' may be
    deleted since it appears not to be so useful, 'sync_timeout' is
    totally unnecessary since any 'sync' can take a timeout per-call.
    
    But the patch is motivated by 'collect_bucket_garbage_interval'
    which is going to become unused in the new GC algorithm.
    
    New GC will be reactive instead of proactive. Instead of periodic
    polling of _bucket space it will react on needed events
    immediately. This will make the 'collect interval' unused.
    
    The option will be deprecated and eventually in some far future
    release its usage will lead to an error.
    
    Needed for #147

diff --git a/vshard/cfg.lua b/vshard/cfg.lua
index 1ef1899..f7d5dbc 100644
--- a/vshard/cfg.lua
+++ b/vshard/cfg.lua
@@ -59,7 +59,17 @@ local function validate_config(config, template, check_arg)
         local value = config[key]
         local name = template_value.name
         local expected_type = template_value.type
-        if value == nil then
+        if template_value.is_deprecated then
+            if value ~= nil then
+                local reason = template_value.reason
+                if reason then
+                    reason = '. '..reason
+                else
+                    reason = ''
+                end
+                log.warn('Option "%s" is deprecated'..reason, name)
+            end
+        elseif value == nil then
             if not template_value.is_optional then
                 error(string.format('%s must be specified', name))
             else

====================