Add API UpdateRuntimeArgs for updating the module arguments during ru…

…ntime (valkey-io#1041)

Before Redis OSS 7, if we load a module with some arguments during
runtime,
and run the command "config rewrite", the module information will not be
saved into the
config file.

Since Redis OSS 7 and Valkey 7.2, if we load a module with some
arguments during runtime,
the module information (path, arguments number, and arguments value) can
be saved into the config file after config rewrite command is called.
Thus, the module will be loaded automatically when the server startup
next time.

Following is one example:

bind 172.25.0.58
port 7000
protected-mode no
enable-module-command yes

Generated by CONFIG REWRITE
latency-tracking-info-percentiles 50 99 99.9
dir "/home/ubuntu/valkey"
save 3600 1 300 100 60 10000
user default on nopass sanitize-payload ~* &* +https://github.com/ALL
loadmodule tests/modules/datatype.so 10 20

However, there is one problem.
If developers write a module, and update the running arguments by
someway, the updated arguments can not be saved into the config file
even "config rewrite" is called.
The reason comes from the following function
rewriteConfigLoadmoduleOption (src/config.c)

void rewriteConfigLoadmoduleOption(struct rewriteConfigState *state) {
..........
struct ValkeyModule *module = dictGetVal(de);
line = sdsnew("loadmodule ");
line = sdscatsds(line, module->loadmod->path);
for (int i = 0; i < module->loadmod->argc; i++) {
line = sdscatlen(line, " ", 1);
line = sdscatsds(line, module->loadmod->argv[i]->ptr);
}
rewriteConfigRewriteLine(state, "loadmodule", line, 1);
.......
}

The function only save the initial arguments information
(module->loadmod) into the configfile.

After core members discuss, ref
valkey-io#1177


We decide add the following API to implement this feature:

Original proposal:

int VM_UpdateRunTimeArgs(ValkeyModuleCtx *ctx, int index, char *value);


Updated proposal:

ValkeyModuleString **values VM_GetRuntimeArgs(ValkeyModuleCtx *ctx);
**int VM_UpdateRuntimeArgs(ValkeyModuleCtx *ctx, int argc,
ValkeyModuleString **values);



Why we do not recommend the following way: 


MODULE UNLOAD
Update module args in the conf file
MODULE LOAD

I think there are the following disadvantages:

1. Some modules can not be unloaded. Such as the example module
datatype.so, which is tests/modules/datatype.so
2. it is not atomic operation for MODULE UNLOAD + MODULE LOAD
3. sometimes, if we just run the module unload, the client business
could be interrupted

---------

Signed-off-by: hwware <[email protected]>

src/module.c

@@ -2255,6 +2255,27 @@ int moduleIsModuleCommand(void *module_handle, struct serverCommand *cmd) {
     return (cp->module == module_handle);
 }
 
+/* ValkeyModule_UpdateRuntimeArgs can be used to update the module argument values.
+ * The function parameter 'argc' indicates the number of updated arguments, and 'argv'
+ * represents the values of the updated arguments.
+ * Once 'CONFIG REWRITE' command is called, the updated argument values can be saved into conf file.
+ *
+ * The function always returns VALKEYMODULE_OK. */
+int VM_UpdateRuntimeArgs(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, int argc) {
+    struct moduleLoadQueueEntry *loadmod = ctx->module->loadmod;
+    for (int i = 0; i < loadmod->argc; i++) {
+        decrRefCount(loadmod->argv[i]);
+    }
+    zfree(loadmod->argv);
+    loadmod->argv = argc - 1 ? zmalloc(sizeof(robj *) * (argc - 1)) : NULL;
+    loadmod->argc = argc - 1;
+    for (int i = 1; i < argc; i++) {
+        loadmod->argv[i - 1] = argv[i];
+        incrRefCount(loadmod->argv[i - 1]);
+    }
+    return VALKEYMODULE_OK;
+}
+
 /* --------------------------------------------------------------------------
  * ## Module information and time measurement
  * -------------------------------------------------------------------------- */
@@ -13560,6 +13581,7 @@ void moduleRegisterCoreAPI(void) {
     REGISTER_API(SetModuleAttribs);
     REGISTER_API(IsModuleNameBusy);
     REGISTER_API(WrongArity);
+    REGISTER_API(UpdateRuntimeArgs);
     REGISTER_API(ReplyWithLongLong);
     REGISTER_API(ReplyWithError);
     REGISTER_API(ReplyWithErrorFormat);

src/valkeymodule.h

@@ -967,6 +967,7 @@ VALKEYMODULE_API void (*ValkeyModule_SetModuleAttribs)(ValkeyModuleCtx *ctx, con
     VALKEYMODULE_ATTR;
 VALKEYMODULE_API int (*ValkeyModule_IsModuleNameBusy)(const char *name) VALKEYMODULE_ATTR;
 VALKEYMODULE_API int (*ValkeyModule_WrongArity)(ValkeyModuleCtx *ctx) VALKEYMODULE_ATTR;
+VALKEYMODULE_API int (*ValkeyModule_UpdateRuntimeArgs)(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, int argc) VALKEYMODULE_ATTR;
 VALKEYMODULE_API int (*ValkeyModule_ReplyWithLongLong)(ValkeyModuleCtx *ctx, long long ll) VALKEYMODULE_ATTR;
 VALKEYMODULE_API int (*ValkeyModule_GetSelectedDb)(ValkeyModuleCtx *ctx) VALKEYMODULE_ATTR;
 VALKEYMODULE_API int (*ValkeyModule_SelectDb)(ValkeyModuleCtx *ctx, int newid) VALKEYMODULE_ATTR;
@@ -1673,6 +1674,7 @@ static int ValkeyModule_Init(ValkeyModuleCtx *ctx, const char *name, int ver, in
     VALKEYMODULE_GET_API(SetModuleAttribs);
     VALKEYMODULE_GET_API(IsModuleNameBusy);
     VALKEYMODULE_GET_API(WrongArity);
+    VALKEYMODULE_GET_API(UpdateRuntimeArgs);
     VALKEYMODULE_GET_API(ReplyWithLongLong);
     VALKEYMODULE_GET_API(ReplyWithError);
     VALKEYMODULE_GET_API(ReplyWithErrorFormat);

tests/modules/Makefile

@@ -58,6 +58,7 @@ TEST_MODULES = \
     eventloop.so \
     moduleconfigs.so \
     moduleconfigstwo.so \
+    moduleparameter.so \
     publish.so \
     usercall.so \
     postnotifications.so \

tests/modules/moduleparameter.c

@@ -0,0 +1,28 @@
+#include "valkeymodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+
+int test_module_update_parameter(ValkeyModuleCtx *ctx,
+                                 ValkeyModuleString **argv, int argc) {
+
+  ValkeyModule_UpdateRuntimeArgs(ctx, argv, argc);
+  return ValkeyModule_ReplyWithSimpleString(ctx, "OK");
+}
+
+int ValkeyModule_OnLoad(ValkeyModuleCtx *ctx, ValkeyModuleString **argv, int argc) {
+    VALKEYMODULE_NOT_USED(argv);
+    VALKEYMODULE_NOT_USED(argc);
+
+    if (ValkeyModule_Init(ctx, "moduleparameter", 1, VALKEYMODULE_APIVER_1) ==
+        VALKEYMODULE_ERR)
+      return VALKEYMODULE_ERR;
+
+    if (ValkeyModule_CreateCommand(ctx, "testmoduleparameter.update.parameter",
+                                   test_module_update_parameter, "fast", 0, 0,
+                                   0) == VALKEYMODULE_ERR)
+      return VALKEYMODULE_ERR;
+
+    return VALKEYMODULE_OK;
+}

tests/unit/moduleapi/moduleconfigs.tcl

@@ -1,5 +1,7 @@
 set testmodule [file normalize tests/modules/moduleconfigs.so]
 set testmoduletwo [file normalize tests/modules/moduleconfigstwo.so]
+set testmoduleparameter [file normalize tests/modules/moduleparameter.so]
+
 
 start_server {tags {"modules"}} {
     r module load $testmodule
@@ -243,5 +245,14 @@ start_server {tags {"modules"}} {
             assert_equal [r config get moduleconfigs.memory_numeric] "moduleconfigs.memory_numeric 1024"
         }
     }
-}
+    test {Module Update Args} {
+       r module load $testmoduleparameter 10 20 30
 
+       set t [r module list]
+       set modulename [lmap x [r module list] {dict get $x name}]
+       assert_not_equal [lsearch $modulename moduleparameter] -1
+       assert_equal "{10 20 30}" [lmap x [r module list] {dict get $x args}]
+       assert_equal OK [r testmoduleparameter.update.parameter 40 50 60 70]
+       assert_equal "{40 50 60 70}" [lmap x [r module list] {dict get $x args}]
+    }
+}