From: Vladimir Davydov <vdavydov.dev@gmail.com> To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org> Cc: tarantool-patches@freelists.org Subject: Re: [PATCH 2/2] schema: expose space_mt and index_mt on `box.schema` table Date: Mon, 2 Apr 2018 14:28:43 +0300 [thread overview] Message-ID: <20180402112843.k5szaedwomi4gtl3@esperanza> (raw) In-Reply-To: <95fd6df65760120d64d3dc7cd4f2c2c322ff76ff.1522580337.git.v.shpilevoy@tarantool.org> On Sun, Apr 01, 2018 at 02:02:46PM +0300, Vladislav Shpilevoy wrote: > function box.schema.space.bless(space) > - local index_mt = table.deepcopy(index_mt) > - local space_mt = table.deepcopy(space_mt) > + -- At first, reference all global index functions. At second, > + -- choose an implementation for read operations. They are not > + -- in a global index_mt, because they are engine specific. > + -- All common index_mt functions must be referenced here to > + -- be able to get them using getmetatable(index_object) - if > + -- they are only in index_mt, then getmetatable() returns only > + -- read ops. > + local local_index_mt = table.deepcopy(index_mt) > + local_index_mt.__index = function(index, key) > + return local_index_mt[key] or index_mt[key] > + end I don't really like that you use the same metatable for all spaces, but a separate metatable for each index. Besides, because of this one can't overwrite a built-in method (e.g. 'get') as it will be masked by local_index_mt. AFAIU you do this, because vinyl and memtx use different methods (luac vs ffi) for certain operations. I see the following alternatives: 1. Leave as is. This isn't all so bad. After all, I doubt anybody's actually willing to overwrite built-in methods. 2. Use two metatables, one for all memtx indexes, another for vinyl, and push all changes from the public index_mt to both of these metatables. Not quite sure it's technically possible in Lua. 3. Same as #2, but proscribe modification of built-in methods. 4. Add a separate engine-specific metatable for the method that differ between memtx and vinyl, then define __index as: local engine_index_mt = (engine == 'memtx' and memtx_index_mt or vinyl_index_mt) index_mt.__index = function(index, key) return index_mt[key] or engine_index_mt[key] Personally, I like #4 most, but it may affect performance. Anyway, I guess this is up to Kostja to decide which one to choose. I don't see any other technical problems in the patch, nor in the test. > -- true if reading operations may yield > local read_yields = space.engine == 'vinyl' > local read_ops = {'select', 'get', 'min', 'max', 'count', 'random', 'pairs'} > for _, op in ipairs(read_ops) do > if read_yields then > -- use Lua/C implmenetation > - index_mt[op] = index_mt[op .. "_luac"] > + local_index_mt[op] = index_mt[op .. "_luac"] > else > -- use FFI implementation > - index_mt[op] = index_mt[op .. "_ffi"] > + local_index_mt[op] = index_mt[op .. "_ffi"] > end > end > index_mt.__pairs = index_mt.pairs -- Lua 5.2 compatibility > @@ -1430,7 +1441,7 @@ function box.schema.space.bless(space) > if type(space.index) == 'table' and space.enabled then > for j, index in pairs(space.index) do > if type(j) == 'number' then > - setmetatable(index, index_mt) > + setmetatable(index, local_index_mt) > end > end > end
next prev parent reply other threads:[~2018-04-02 11:28 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-23 13:07 [PATCH 0/2] schema: expose space_mt and index_mt on table Vladislav Shpilevoy 2018-03-23 13:07 ` [PATCH 1/2] schema: expose space_mt and index_mt on `box.schema` table Vladislav Shpilevoy 2018-03-23 13:07 ` [PATCH 2/2] schema: review fixes for box.schema.space/index metatables Vladislav Shpilevoy 2018-03-29 10:54 ` [PATCH 0/2] schema: expose space_mt and index_mt on table Vladimir Davydov 2018-03-29 14:31 ` [PATCH v2 0/2] schema: expose space_mt and index_mt on box.schema table Vladislav Shpilevoy 2018-03-29 14:31 ` [PATCH v2 1/2] schema: move space_mt and index_mt definition out of space bless Vladislav Shpilevoy 2018-04-01 9:33 ` Vladimir Davydov 2018-04-01 11:02 ` [PATCH 0/2] schema: expose space_mt and index_mt on box.schema table Vladislav Shpilevoy 2018-04-01 11:02 ` [PATCH 1/2] schema: move space_mt and index_mt definition out of space bless Vladislav Shpilevoy 2018-04-01 11:02 ` [PATCH 2/2] schema: expose space_mt and index_mt on `box.schema` table Vladislav Shpilevoy 2018-04-02 11:28 ` Vladimir Davydov [this message] 2018-04-03 16:50 ` [PATCH v2 0/3] schema: expose space_mt and index_mt on box.schema table Vladislav Shpilevoy 2018-04-03 16:50 ` [PATCH v2 1/3] schema: move space_mt and index_mt definition out of space bless Vladislav Shpilevoy 2018-04-03 16:50 ` [PATCH v2 2/3] schema: inherit vinyl/memtx_index_mt from base index mt Vladislav Shpilevoy 2018-04-03 16:50 ` [PATCH v2 3/3] schema: expose space_mt and index_mt on box.schema table Vladislav Shpilevoy 2018-05-05 12:47 ` [tarantool-patches] " Vladislav Shpilevoy 2018-05-08 16:48 ` Konstantin Osipov 2018-05-08 17:33 ` Vladislav Shpilevoy 2018-03-29 14:31 ` [PATCH v2 2/2] schema: expose space_mt and index_mt on `box.schema` table Vladislav Shpilevoy 2018-04-01 9:37 ` [PATCH v2 0/2] schema: expose space_mt and index_mt on box.schema table Vladimir Davydov
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