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Remove dead code on sorting reply on Lua scripts. (#10701)

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On v6.2.7 a new mechanism was added to Lua scripts that allows
filtering the globals of the Lua interpreter. This mechanism was
added on the following commit: 11b602fbf8

One of the globals that was filtered out was `__redis__compare_helper`. This global
was missed and was not added to the allow list or to the deny list. This is
why we get the following warning when Redis starts:
`A key '__redis__compare_helper' was added to Lua globals which is not on the globals allow list nor listed on the deny list.`

After investigating the git blame log, the conclusion is that `__redis__compare_helper`
is no longer needed, the PR deletes this function, and fixes the warning.

Detailed Explanation:

`__redis__compare_helper` was added on this commit: https://github.com/redis/redis/commit/2c861050c1
Its purpose is to sort the replies of `SORT` command when script replication is enable and keep the replies
deterministic and avoid primary and replica synchronization issues. On `SORT` command, there was a need for
special compare function that are able to compare boolean values.

The need to sort the `SORT` command reply was removed on this commit: 36741b2c81
The sorting was moved to be part of the `SORT` command and there was not longer a need
to sort it on the Lua interpreter. The commit made `__redis__compare_helper` a dead code but did
not deleted it.

(cherry picked from commit 64c657a8af)
This commit is contained in:
Meir Shpilraien (Spielrein) 2022-12-06 12:22:36 +02:00 committed by Oran Agra
parent 5e841b5533
commit dad7f71f15
1 changed files with 1 additions and 27 deletions
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28
src/scripting.c
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@ -328,21 +328,7 @@ void luaSortArray(lua_State *lua) {
lua_pushstring(lua,"sort");
lua_gettable(lua,-2); /* Stack: array, table, table.sort */
lua_pushvalue(lua,-3); /* Stack: array, table, table.sort, array */
if (lua_pcall(lua,1,0,0)) {
/* Stack: array, table, error */
/* We are not interested in the error, we assume that the problem is
* that there are 'false' elements inside the array, so we try
* again with a slower function but able to handle this case, that
* is: table.sort(table, __redis__compare_helper) */
lua_pop(lua,1); /* Stack: array, table */
lua_pushstring(lua,"sort"); /* Stack: array, table, sort */
lua_gettable(lua,-2); /* Stack: array, table, table.sort */
lua_pushvalue(lua,-3); /* Stack: array, table, table.sort, array */
lua_getglobal(lua,"__redis__compare_helper");
/* Stack: array, table, table.sort, array, __redis__compare_helper */
lua_call(lua,2,0);
}
lua_call(lua,1,0); /* Stack: array (sorted), table */
/* Stack: array (sorted), table */
lua_pop(lua,1); /* Stack: array (sorted) */
}
@ -1256,18 +1242,6 @@ void scriptingInit(int setup) {
lua_setglobal(lua,"math");
/* Add a helper function that we use to sort the multi bulk output of non
* deterministic commands, when containing 'false' elements. */
{
char *compare_func = "function __redis__compare_helper(a,b)\n"
" if a == false then a = '' end\n"
" if b == false then b = '' end\n"
" return a<b\n"
"end\n";
luaL_loadbuffer(lua,compare_func,strlen(compare_func),"@cmp_func_def");
lua_pcall(lua,0,0,0);
}
/* Add a helper function we use for pcall error reporting.
* Note that when the error is in the C function we want to report the
* information about the caller, that's what makes sense from the point