From: Mons Anderson <v.perepelitsa@corp.mail.ru> To: tarantool-patches@dev.tarantool.org Subject: Re: [Tarantool-patches] [RFC 3/4] cfg: prepare symbolic evaluation of replication_synchro_quorum Date: Thu, 26 Nov 2020 17:38:32 +0300 [thread overview] Message-ID: <1670ea9e-ebd6-771b-e3ec-d9edc97d461a@corp.mail.ru> (raw) In-Reply-To: <20201119194100.840495-4-gorcunov@gmail.com> Hi, thanks! Some comments below. On 19.11.2020 22:40, Cyrill Gorcunov wrote: > > +/** > + * Evaluate replicaion syncro quorum number from a formula. > + */ > +int > +eval_replication_synchro_quorum(int nr_replicas) > +{ > + const char fmt[] = > + "local f, err = loadstring(\"return (%s)\")\n" > + "if not f then return 'failed to load \"%s\"' end\n" > + "setfenv(f, { n = %d })\n" > + "local ok, res = pcall(f)\n" > + "if not ok then return res end\n" > + "return math.floor(res)\n"; For the formula evaluation I'd propose the following snippet: local expr = [[%s]] local f, err = loadstring('return ('..expr..')') if not f then error(string.format('Failed to load %%s: %%s',expr, err)) end setfenv(f, { N = %d, math = math }) return math.floor( f() ) The reasons are: - [[ ]] quotes are not interpolated, no need to repeat substitution again - You need to handle errors anyway, so no need to return errors as return values. Throw them. - Also, since error handling (like a pcall from C layer) is required, no need to do pcall inside - Use of uppercase N, not lowercase is desired. Lowercase is used for variables, uppercase for constants. Here N is more constant than variable. (Or we may include eihter N or n) - math module may be used for formulas, so pass it also. > + luaL_loadstring(tarantool_L, buf); > + lua_call(tarantool_L, 0, 1); Use lua_pcall instead lua_call. So then check for absence of error and lua_isnumber > + if (lua_isnumber(tarantool_L, -1)) { > + value = (int)lua_tonumber(tarantool_L, -1); > + } else { > + assert(lua_isstring(tarantool_L, -1)); > + errno = EINVAL; > + diag_set(ClientError, ER_CFG, > + "replication_synchro_quorum", > + lua_tostring(tarantool_L, -1)); > + }
next prev parent reply other threads:[~2020-11-26 14:38 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-19 19:40 [Tarantool-patches] [RFC 0/4] qsync: evaluate replication_synchro_quorum dynamically Cyrill Gorcunov 2020-11-19 19:40 ` [Tarantool-patches] [RFC 1/4] cfg: add cfg_isnumber helper Cyrill Gorcunov 2020-11-20 9:53 ` Serge Petrenko 2020-11-19 19:40 ` [Tarantool-patches] [RFC 2/4] qsync: move synchro quorum update to separate routine Cyrill Gorcunov 2020-11-20 10:06 ` Serge Petrenko 2020-11-20 11:01 ` Cyrill Gorcunov 2020-11-20 11:39 ` Serge Petrenko 2020-11-20 11:47 ` Cyrill Gorcunov 2020-11-19 19:40 ` [Tarantool-patches] [RFC 3/4] cfg: prepare symbolic evaluation of replication_synchro_quorum Cyrill Gorcunov 2020-11-20 10:32 ` Serge Petrenko 2020-11-20 11:34 ` Cyrill Gorcunov 2020-11-20 11:56 ` Serge Petrenko 2020-11-20 12:14 ` Cyrill Gorcunov 2020-11-26 14:38 ` Mons Anderson [this message] 2020-11-26 14:44 ` Cyrill Gorcunov 2020-11-26 16:01 ` Mons Anderson 2020-11-19 19:41 ` [Tarantool-patches] [RFC 4/4] qsync: allow to specify replication_synchro_quorum as a formula Cyrill Gorcunov 2020-11-20 10:50 ` Serge Petrenko 2020-11-20 12:01 ` Cyrill Gorcunov 2020-11-20 12:41 ` Serge Petrenko 2020-11-20 15:00 ` Cyrill Gorcunov
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