Module Configurations (#10285)

This feature adds the ability to add four different types (Bool, Numeric,
String, Enum) of configurations to a module to be accessed via the redis
config file, and the CONFIG command.

**Configuration Names**:

We impose a restriction that a module configuration always starts with the
module name and contains a '.' followed by the config name. If a module passes
"config1" as the name to a register function, it will be registered as MODULENAME.config1.

**Configuration Persistence**:

Module Configurations exist only as long as a module is loaded. If a module is
unloaded, the configurations are removed.
There is now also a minimal core API for removal of standardConfig objects
from configs by name.

**Get and Set Callbacks**:

Storage of config values is owned by the module that registers them, and provides
callbacks for Redis to access and manipulate the values.
This is exposed through a GET and SET callback.

The get callback returns a typed value of the config to redis. The callback takes
the name of the configuration, and also a privdata pointer. Note that these only
take the CONFIGNAME portion of the config, not the entire MODULENAME.CONFIGNAME.

```
 typedef RedisModuleString * (*RedisModuleConfigGetStringFunc)(const char *name, void *privdata);
 typedef long long (*RedisModuleConfigGetNumericFunc)(const char *name, void *privdata);
 typedef int (*RedisModuleConfigGetBoolFunc)(const char *name, void *privdata);
 typedef int (*RedisModuleConfigGetEnumFunc)(const char *name, void *privdata);
```

Configs must also must specify a set callback, i.e. what to do on a CONFIG SET XYZ 123
or when loading configurations from cli/.conf file matching these typedefs. *name* is
again just the CONFIGNAME portion, *val* is the parsed value from the core,
*privdata* is the registration time privdata pointer, and *err* is for providing errors to a client.

```
typedef int (*RedisModuleConfigSetStringFunc)(const char *name, RedisModuleString *val, void *privdata, RedisModuleString **err);
typedef int (*RedisModuleConfigSetNumericFunc)(const char *name, long long val, void *privdata, RedisModuleString **err);
typedef int (*RedisModuleConfigSetBoolFunc)(const char *name, int val, void *privdata, RedisModuleString **err);
typedef int (*RedisModuleConfigSetEnumFunc)(const char *name, int val, void *privdata, RedisModuleString **err);
```

Modules can also specify an optional apply callback that will be called after
value(s) have been set via CONFIG SET:

```
typedef int (*RedisModuleConfigApplyFunc)(RedisModuleCtx *ctx, void *privdata, RedisModuleString **err);
```

**Flags:**
We expose 7 new flags to the module, which are used as part of the config registration.

```
#define REDISMODULE_CONFIG_MODIFIABLE 0 /* This is the default for a module config. */
#define REDISMODULE_CONFIG_IMMUTABLE (1ULL<<0) /* Can this value only be set at startup? */
#define REDISMODULE_CONFIG_SENSITIVE (1ULL<<1) /* Does this value contain sensitive information */
#define REDISMODULE_CONFIG_HIDDEN (1ULL<<4) /* This config is hidden in `config get <pattern>` (used for tests/debugging) */
#define REDISMODULE_CONFIG_PROTECTED (1ULL<<5) /* Becomes immutable if enable-protected-configs is enabled. */
#define REDISMODULE_CONFIG_DENY_LOADING (1ULL<<6) /* This config is forbidden during loading. */
/* Numeric Specific Configs */
#define REDISMODULE_CONFIG_MEMORY (1ULL<<7) /* Indicates if this value can be set as a memory value */
```

**Module Registration APIs**:

```
int (*RedisModule_RegisterBoolConfig)(RedisModuleCtx *ctx, char *name, int default_val, unsigned int flags, RedisModuleConfigGetBoolFunc getfn, RedisModuleConfigSetBoolFunc setfn, RedisModuleConfigApplyFunc applyfn, void *privdata);
int (*RedisModule_RegisterNumericConfig)(RedisModuleCtx *ctx, const char *name, long long default_val, unsigned int flags, long long min, long long max, RedisModuleConfigGetNumericFunc getfn, RedisModuleConfigSetNumericFunc setfn, RedisModuleConfigApplyFunc applyfn, void *privdata);
int (*RedisModule_RegisterStringConfig)(RedisModuleCtx *ctx, const char *name, const char *default_val, unsigned int flags, RedisModuleConfigGetStringFunc getfn, RedisModuleConfigSetStringFunc setfn, RedisModuleConfigApplyFunc applyfn, void *privdata);
int (*RedisModule_RegisterEnumConfig)(RedisModuleCtx *ctx, const char *name, int default_val, unsigned int flags, const char **enum_values, const int *int_values, int num_enum_vals, RedisModuleConfigGetEnumFunc getfn, RedisModuleConfigSetEnumFunc setfn, RedisModuleConfigApplyFunc applyfn, void *privdata);
int (*RedisModule_LoadConfigs)(RedisModuleCtx *ctx);
```

The module name will be auto appended along with a "." to the front of the name of the config.

**What RM_Register[...]Config does**:

A RedisModule struct now keeps a list of ModuleConfig objects which look like:
```
typedef struct ModuleConfig {
    sds name; /* Name of config without the module name appended to the front */
    void *privdata; /* Optional data passed into the module config callbacks */
    union get_fn { /* The get callback specificed by the module */
        RedisModuleConfigGetStringFunc get_string;
        RedisModuleConfigGetNumericFunc get_numeric;
        RedisModuleConfigGetBoolFunc get_bool;
        RedisModuleConfigGetEnumFunc get_enum;
    } get_fn;
    union set_fn { /* The set callback specified by the module */
        RedisModuleConfigSetStringFunc set_string;
        RedisModuleConfigSetNumericFunc set_numeric;
        RedisModuleConfigSetBoolFunc set_bool;
        RedisModuleConfigSetEnumFunc set_enum;
    } set_fn;
    RedisModuleConfigApplyFunc apply_fn;
    RedisModule *module;
} ModuleConfig;
```
It also registers a standardConfig in the configs array, with a pointer to the
ModuleConfig object associated with it.

**What happens on a CONFIG GET/SET MODULENAME.MODULECONFIG:**

For CONFIG SET, we do the same parsing as is done in config.c and pass that
as the argument to the module set callback. For CONFIG GET, we call the
module get callback and return that value to config.c to return to a client.

**CONFIG REWRITE**:

Starting up a server with module configurations in a .conf file but no module load
directive will fail. The flip side is also true, specifying a module load and a bunch
of module configurations will load those configurations in using the module defined
set callbacks on a RM_LoadConfigs call. Configs being rewritten works the same
way as it does for standard configs, as the module has the ability to specify a
default value. If a module is unloaded with configurations specified in the .conf file
those configurations will be commented out from the .conf file on the next config rewrite.

**RM_LoadConfigs:**

`RedisModule_LoadConfigs(RedisModuleCtx *ctx);`

This last API is used to make configs available within the onLoad() after they have
been registered. The expected usage is that a module will register all of its configs,
then call LoadConfigs to trigger all of the set callbacks, and then can error out if any
of them were malformed. LoadConfigs will attempt to set all configs registered to
either a .conf file argument/loadex argument or their default value if an argument is
not specified. **LoadConfigs is a required function if configs are registered.
** Also note that LoadConfigs **does not** call the apply callbacks, but a module
can do that directly after the LoadConfigs call.

**New Command: MODULE LOADEX [CONFIG NAME VALUE] [ARGS ...]:**

This command provides the ability to provide startup context information to a module.
LOADEX stands for "load extended" similar to GETEX. Note that provided config
names need the full MODULENAME.MODULECONFIG name. Any additional
arguments a module might want are intended to be specified after ARGS.
Everything after ARGS is passed to onLoad as RedisModuleString **argv.

Co-authored-by: Madelyn Olson <madelyneolson@gmail.com>
Co-authored-by: Madelyn Olson <matolson@amazon.com>
Co-authored-by: sundb <sundbcn@gmail.com>
Co-authored-by: Madelyn Olson <34459052+madolson@users.noreply.github.com>
Co-authored-by: Oran Agra <oran@redislabs.com>
Co-authored-by: Yossi Gottlieb <yossigo@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/runtest-moduleapi b/runtest-moduleapi
index a3aab1f7a..38c0d5434 100755
--- a/runtest-moduleapi
+++ b/runtest-moduleapi
@@ -20,6 +20,7 @@ $TCLSH tests/test_helper.tcl \
 --single unit/moduleapi/fork \
 --single unit/moduleapi/testrdb \
 --single unit/moduleapi/infotest \
+--single unit/moduleapi/moduleconfigs \
 --single unit/moduleapi/infra \
 --single unit/moduleapi/propagate \
 --single unit/moduleapi/hooks \