Re: [Tarantool-patches] [PATCH v2 2/3] cfg: support symbolic evaluation of replication_synchro_quorum

[Serge Petrenko <sergepetrenko@tarantool.org>]

24.11.2020 18:24, Cyrill Gorcunov пишет:
> diff --git a/src/box/box.cc b/src/box/box.cc
> index 1f7dec362..e4cb013c3 100644
> --- a/src/box/box.cc
> +++ b/src/box/box.cc
> @@ -562,10 +562,81 @@ box_check_replication_sync_lag(void)
>   	return lag;
>   }
>   
> +/**
> + * Evaluate replication syncro quorum number from a formula.
> + */
> +static 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";
> +	char buf[512];
> +	int value = -1;
> +
> +	const char *expr = cfg_gets("replication_synchro_quorum");
> +	size_t ret = snprintf(buf, sizeof(buf), fmt, expr,
> +			      expr, nr_replicas);
> +	if (ret >= sizeof(buf)) {
> +		diag_set(ClientError, ER_CFG,
> +			 "replication_synchro_quorum",
> +			 "the expression is too big");
> +		return -1;
> +	}


Just noticed. Looks like this diag_set and the one below are ignored:
```


tarantool> a=string.rep('n', 1000)
---
...

tarantool> box.cfg{replication_synchro_quorum=a}
---
- error: 'Incorrect value for option ''replication_synchro_quorum'': the 
value must
     be greater than zero and less than maximal number of replicas'
...

```

> +
> +	luaL_loadstring(tarantool_L, buf);
> +	lua_call(tarantool_L, 0, 1);
> +
> +	if (lua_isnumber(tarantool_L, -1)) {
> +		value = (int)lua_tonumber(tarantool_L, -1);
> +	} else {
> +		diag_set(ClientError, ER_CFG,
> +			 "replication_synchro_quorum",
> +			 lua_tostring(tarantool_L, -1));
> +		return -1;
> +	}

Same for this diag_set:

```

tarantool> box.cfg{replication_synchro_quorum="garbage"}
---
- error: 'Incorrect value for option ''replication_synchro_quorum'': the 
value must
     be greater than zero and less than maximal number of replicas'
...

```

-- 
Serge Petrenko