Extract the scripting engine code from the functions unit (#1312)

This commit creates a new compilation unit for the scripting engine code
by extracting the existing code from the functions unit.
We're doing this refactor to prepare the code for running the `EVAL`
command using different scripting engines.

This PR has a module API change: we changed the type of error messages
returned by the callback
`ValkeyModuleScriptingEngineCreateFunctionsLibraryFunc` to be a
`ValkeyModuleString` (aka `robj`);

This PR also fixes #1470.

---------

Signed-off-by: Ricardo Dias <ricardo.dias@percona.com>

cmake/Modules/SourceFiles.cmake

@@ -100,6 +100,7 @@ set(VALKEY_SERVER_SRCS
     ${CMAKE_SOURCE_DIR}/src/script_lua.c
     ${CMAKE_SOURCE_DIR}/src/script.c
     ${CMAKE_SOURCE_DIR}/src/functions.c
+    ${CMAKE_SOURCE_DIR}/src/scripting_engine.c
     ${CMAKE_SOURCE_DIR}/src/function_lua.c
     ${CMAKE_SOURCE_DIR}/src/commands.c
     ${CMAKE_SOURCE_DIR}/src/strl.c

src/Makefile

@@ -374,7 +374,7 @@ else
     endef
 endif
 
-# Determine install/uninstall Redis symlinks for compatibility when 
+# Determine install/uninstall Redis symlinks for compatibility when
 # installing/uninstalling Valkey binaries (defaulting to `yes`)
 USE_REDIS_SYMLINKS?=yes
 ifeq ($(USE_REDIS_SYMLINKS),yes)
@@ -416,7 +416,7 @@ endif
 ENGINE_NAME=valkey
 SERVER_NAME=$(ENGINE_NAME)-server$(PROG_SUFFIX)
 ENGINE_SENTINEL_NAME=$(ENGINE_NAME)-sentinel$(PROG_SUFFIX)
-ENGINE_SERVER_OBJ=threads_mngr.o adlist.o quicklist.o ae.o anet.o dict.o hashtable.o kvstore.o server.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o memory_prefetch.o io_threads.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o pubsub.o multi.o debug.o sort.o intset.o syncio.o cluster.o cluster_legacy.o cluster_slot_stats.o crc16.o endianconv.o slowlog.o eval.o bio.o rio.o rand.o memtest.o syscheck.o crcspeed.o crccombine.o crc64.o bitops.o sentinel.o notify.o setproctitle.o blocked.o hyperloglog.o latency.o sparkline.o valkey-check-rdb.o valkey-check-aof.o geo.o lazyfree.o module.o evict.o expire.o geohash.o geohash_helper.o childinfo.o allocator_defrag.o defrag.o siphash.o rax.o t_stream.o listpack.o localtime.o lolwut.o lolwut5.o lolwut6.o acl.o tracking.o socket.o tls.o sha256.o timeout.o setcpuaffinity.o monotonic.o mt19937-64.o resp_parser.o call_reply.o script_lua.o script.o functions.o function_lua.o commands.o strl.o connection.o unix.o logreqres.o rdma.o
+ENGINE_SERVER_OBJ=threads_mngr.o adlist.o quicklist.o ae.o anet.o dict.o hashtable.o kvstore.o server.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o memory_prefetch.o io_threads.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o pubsub.o multi.o debug.o sort.o intset.o syncio.o cluster.o cluster_legacy.o cluster_slot_stats.o crc16.o endianconv.o slowlog.o eval.o bio.o rio.o rand.o memtest.o syscheck.o crcspeed.o crccombine.o crc64.o bitops.o sentinel.o notify.o setproctitle.o blocked.o hyperloglog.o latency.o sparkline.o valkey-check-rdb.o valkey-check-aof.o geo.o lazyfree.o module.o evict.o expire.o geohash.o geohash_helper.o childinfo.o allocator_defrag.o defrag.o siphash.o rax.o t_stream.o listpack.o localtime.o lolwut.o lolwut5.o lolwut6.o acl.o tracking.o socket.o tls.o sha256.o timeout.o setcpuaffinity.o monotonic.o mt19937-64.o resp_parser.o call_reply.o script_lua.o script.o functions.o function_lua.o commands.o strl.o connection.o unix.o logreqres.o rdma.o scripting_engine.o
 ENGINE_CLI_NAME=$(ENGINE_NAME)-cli$(PROG_SUFFIX)
 ENGINE_CLI_OBJ=anet.o adlist.o dict.o valkey-cli.o zmalloc.o release.o ae.o serverassert.o crcspeed.o crccombine.o crc64.o siphash.o crc16.o monotonic.o cli_common.o mt19937-64.o strl.o cli_commands.o
 ENGINE_BENCHMARK_NAME=$(ENGINE_NAME)-benchmark$(PROG_SUFFIX)

src/function_lua.c

@@ -39,6 +39,7 @@
  * Uses script_lua.c to run the Lua code.
  */
 
+#include "scripting_engine.h"
 #include "functions.h"
 #include "script_lua.h"
 #include <lua.h>
@@ -121,7 +122,7 @@ static compiledFunction **luaEngineCreate(ValkeyModuleCtx *module_ctx,
                                           const char *code,
                                           size_t timeout,
                                           size_t *out_num_compiled_functions,
-                                          char **err) {
+                                          robj **err) {
     /* The lua engine is implemented in the core, and not in a Valkey Module */
     serverAssert(module_ctx == NULL);
 
@@ -139,7 +140,8 @@ static compiledFunction **luaEngineCreate(ValkeyModuleCtx *module_ctx,
 
     /* compile the code */
     if (luaL_loadbuffer(lua, code, strlen(code), "@user_function")) {
-        *err = valkey_asprintf("Error compiling function: %s", lua_tostring(lua, -1));
+        sds error = sdscatfmt(sdsempty(), "Error compiling function: %s", lua_tostring(lua, -1));
+        *err = createObject(OBJ_STRING, error);
         lua_pop(lua, 1); /* pops the error */
         goto done;
     }
@@ -157,7 +159,8 @@ static compiledFunction **luaEngineCreate(ValkeyModuleCtx *module_ctx,
     if (lua_pcall(lua, 0, 0, 0)) {
         errorInfo err_info = {0};
         luaExtractErrorInformation(lua, &err_info);
-        *err = valkey_asprintf("Error registering functions: %s", err_info.msg);
+        sds error = sdscatfmt(sdsempty(), "Error registering functions: %s", err_info.msg);
+        *err = createObject(OBJ_STRING, error);
         lua_pop(lua, 1); /* pops the error */
         luaErrorInformationDiscard(&err_info);
         listIter *iter = listGetIterator(load_ctx.functions, AL_START_HEAD);
@@ -557,8 +560,8 @@ int luaEngineInitEngine(void) {
         .get_memory_info = luaEngineGetMemoryInfo,
     };
 
-    return functionsRegisterEngine(LUA_ENGINE_NAME,
-                                   NULL,
-                                   lua_engine_ctx,
-                                   &lua_engine_methods);
+    return scriptingEngineManagerRegister(LUA_ENGINE_NAME,
+                                          NULL,
+                                          lua_engine_ctx,
+                                          &lua_engine_methods);
 }