Match REDISMODULE_OPEN_KEY_* flags to LOOKUP_* flags (#11772)

The PR adds support for the following flags on RedisModule_OpenKey:

* REDISMODULE_OPEN_KEY_NONOTIFY - Don't trigger keyspace event on key misses.
* REDISMODULE_OPEN_KEY_NOSTATS - Don't update keyspace hits/misses counters.
* REDISMODULE_OPEN_KEY_NOEXPIRE - Avoid deleting lazy expired keys.
* REDISMODULE_OPEN_KEY_NOEFFECTS - Avoid any effects from fetching the key

In addition, added `RM_GetOpenKeyModesAll`, which returns the mask of all
supported OpenKey modes. This allows the module to check, in runtime, which
OpenKey modes are supported by the current Redis instance.

src/blocked.c

@@ -544,7 +544,7 @@ static void handleClientsBlockedOnKey(readyList *rl) {
 
         while((ln = listNext(&li))) {
             client *receiver = listNodeValue(ln);
-            robj *o = lookupKeyReadWithFlags(rl->db, rl->key, LOKKUP_NOEFFECTS);
+            robj *o = lookupKeyReadWithFlags(rl->db, rl->key, LOOKUP_NOEFFECTS);
             /* 1. In case new key was added/touched we need to verify it satisfy the
              *    blocked type, since we might process the wrong key type.
              * 2. We want to serve clients blocked on module keys

src/module.c

@@ -3783,17 +3783,29 @@ static void moduleInitKeyTypeSpecific(RedisModuleKey *key) {
  * The return value is the handle representing the key, that must be
  * closed with RM_CloseKey().
  *
- * If the key does not exist and WRITE mode is requested, the handle
+ * If the key does not exist and REDISMODULE_WRITE mode is requested, the handle
  * is still returned, since it is possible to perform operations on
  * a yet not existing key (that will be created, for example, after
- * a list push operation). If the mode is just READ instead, and the
+ * a list push operation). If the mode is just REDISMODULE_READ instead, and the
  * key does not exist, NULL is returned. However it is still safe to
  * call RedisModule_CloseKey() and RedisModule_KeyType() on a NULL
- * value. */
+ * value.
+ *
+ * Extra flags that can be pass to the API under the mode argument:
+ * * REDISMODULE_OPEN_KEY_NOTOUCH - Avoid touching the LRU/LFU of the key when opened.
+ * * REDISMODULE_OPEN_KEY_NONOTIFY - Don't trigger keyspace event on key misses.
+ * * REDISMODULE_OPEN_KEY_NOSTATS - Don't update keyspace hits/misses counters.
+ * * REDISMODULE_OPEN_KEY_NOEXPIRE - Avoid deleting lazy expired keys.
+ * * REDISMODULE_OPEN_KEY_NOEFFECTS - Avoid any effects from fetching the key. */
 RedisModuleKey *RM_OpenKey(RedisModuleCtx *ctx, robj *keyname, int mode) {
     RedisModuleKey *kp;
     robj *value;
-    int flags = mode & REDISMODULE_OPEN_KEY_NOTOUCH? LOOKUP_NOTOUCH: 0;
+    int flags = 0;
+    flags |= (mode & REDISMODULE_OPEN_KEY_NOTOUCH? LOOKUP_NOTOUCH: 0);
+    flags |= (mode & REDISMODULE_OPEN_KEY_NONOTIFY? LOOKUP_NONOTIFY: 0);
+    flags |= (mode & REDISMODULE_OPEN_KEY_NOSTATS? LOOKUP_NOSTATS: 0);
+    flags |= (mode & REDISMODULE_OPEN_KEY_NOEXPIRE? LOOKUP_NOEXPIRE: 0);
+    flags |= (mode & REDISMODULE_OPEN_KEY_NOEFFECTS? LOOKUP_NOEFFECTS: 0);
 
     if (mode & REDISMODULE_WRITE) {
         value = lookupKeyWriteWithFlags(ctx->client->db,keyname, flags);
@@ -3811,6 +3823,23 @@ RedisModuleKey *RM_OpenKey(RedisModuleCtx *ctx, robj *keyname, int mode) {
     return kp;
 }
 
+/**
+ * Returns the full OpenKey modes mask, using the return value
+ * the module can check if a certain set of OpenKey modes are supported
+ * by the redis server version in use.
+ * Example:
+ *
+ *        int supportedMode = RM_GetOpenKeyModesAll();
+ *        if (supportedMode & REDISMODULE_OPEN_KEY_NOTOUCH) {
+ *              // REDISMODULE_OPEN_KEY_NOTOUCH is supported
+ *        } else{
+ *              // REDISMODULE_OPEN_KEY_NOTOUCH is not supported
+ *        }
+ */
+int RM_GetOpenKeyModesAll() {
+    return _REDISMODULE_OPEN_KEY_ALL;
+}
+
 /* Destroy a RedisModuleKey struct (freeing is the responsibility of the caller). */
 static void moduleCloseKey(RedisModuleKey *key) {
     int signal = SHOULD_SIGNAL_MODIFIED_KEYS(key->ctx);
@@ -12809,6 +12838,7 @@ void moduleRegisterCoreAPI(void) {
     REGISTER_API(SelectDb);
     REGISTER_API(KeyExists);
     REGISTER_API(OpenKey);
+    REGISTER_API(GetOpenKeyModesAll);
     REGISTER_API(CloseKey);
     REGISTER_API(KeyType);
     REGISTER_API(ValueLength);

src/redismodule.h

@@ -48,6 +48,18 @@ typedef long long ustime_t;
 /* RedisModule_OpenKey extra flags for the 'mode' argument.
  * Avoid touching the LRU/LFU of the key when opened. */
 #define REDISMODULE_OPEN_KEY_NOTOUCH (1<<16)
+/* Don't trigger keyspace event on key misses. */
+#define REDISMODULE_OPEN_KEY_NONOTIFY (1<<17)
+/* Don't update keyspace hits/misses counters. */
+#define REDISMODULE_OPEN_KEY_NOSTATS (1<<18)
+/* Avoid deleting lazy expired keys. */
+#define REDISMODULE_OPEN_KEY_NOEXPIRE (1<<19)
+/* Avoid any effects from fetching the key */
+#define REDISMODULE_OPEN_KEY_NOEFFECTS (1<<20)
+/* Mask of all REDISMODULE_OPEN_KEY_* values. Any new mode should be added to this list.
+ * Should not be used directly by the module, use RM_GetOpenKeyModesAll instead.
+ * Located here so when we will add new modes we will not forget to update it. */
+#define _REDISMODULE_OPEN_KEY_ALL REDISMODULE_READ | REDISMODULE_WRITE | REDISMODULE_OPEN_KEY_NOTOUCH | REDISMODULE_OPEN_KEY_NONOTIFY | REDISMODULE_OPEN_KEY_NOSTATS | REDISMODULE_OPEN_KEY_NOEXPIRE | REDISMODULE_OPEN_KEY_NOEFFECTS
 
 /* List push and pop */
 #define REDISMODULE_LIST_HEAD 0
@@ -955,6 +967,7 @@ REDISMODULE_API int (*RedisModule_GetSelectedDb)(RedisModuleCtx *ctx) REDISMODUL
 REDISMODULE_API int (*RedisModule_SelectDb)(RedisModuleCtx *ctx, int newid) REDISMODULE_ATTR;
 REDISMODULE_API int (*RedisModule_KeyExists)(RedisModuleCtx *ctx, RedisModuleString *keyname) REDISMODULE_ATTR;
 REDISMODULE_API RedisModuleKey * (*RedisModule_OpenKey)(RedisModuleCtx *ctx, RedisModuleString *keyname, int mode) REDISMODULE_ATTR;
+REDISMODULE_API int (*RedisModule_GetOpenKeyModesAll)() REDISMODULE_ATTR;
 REDISMODULE_API void (*RedisModule_CloseKey)(RedisModuleKey *kp) REDISMODULE_ATTR;
 REDISMODULE_API int (*RedisModule_KeyType)(RedisModuleKey *kp) REDISMODULE_ATTR;
 REDISMODULE_API size_t (*RedisModule_ValueLength)(RedisModuleKey *kp) REDISMODULE_ATTR;
@@ -1326,6 +1339,7 @@ static int RedisModule_Init(RedisModuleCtx *ctx, const char *name, int ver, int
     REDISMODULE_GET_API(SelectDb);
     REDISMODULE_GET_API(KeyExists);
     REDISMODULE_GET_API(OpenKey);
+    REDISMODULE_GET_API(GetOpenKeyModesAll);
     REDISMODULE_GET_API(CloseKey);
     REDISMODULE_GET_API(KeyType);
     REDISMODULE_GET_API(ValueLength);

src/server.h

@@ -3155,7 +3155,7 @@ int objectSetLRUOrLFU(robj *val, long long lfu_freq, long long lru_idle,
 #define LOOKUP_NOSTATS (1<<2)  /* Don't update keyspace hits/misses counters. */
 #define LOOKUP_WRITE (1<<3)    /* Delete expired keys even in replicas. */
 #define LOOKUP_NOEXPIRE (1<<4) /* Avoid deleting lazy expired keys. */
-#define LOKKUP_NOEFFECTS (LOOKUP_NONOTIFY | LOOKUP_NOSTATS | LOOKUP_NOTOUCH | LOOKUP_NOEXPIRE) /* Avoid any effects from fetching the key */
+#define LOOKUP_NOEFFECTS (LOOKUP_NONOTIFY | LOOKUP_NOSTATS | LOOKUP_NOTOUCH | LOOKUP_NOEXPIRE) /* Avoid any effects from fetching the key */
 
 void dbAdd(redisDb *db, robj *key, robj *val);
 int dbAddRDBLoad(redisDb *db, sds key, robj *val);

tests/modules/misc.c

@@ -8,6 +8,55 @@
 
 #define UNUSED(x) (void)(x)
 
+static int n_events = 0;
+
+static int KeySpace_NotificationModuleKeyMissExpired(RedisModuleCtx *ctx, int type, const char *event, RedisModuleString *key) {
+    UNUSED(ctx);
+    UNUSED(type);
+    UNUSED(event);
+    UNUSED(key);
+    n_events++;
+    return REDISMODULE_OK;
+}
+
+int test_clear_n_events(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    UNUSED(argv);
+    UNUSED(argc);
+    n_events = 0;
+    RedisModule_ReplyWithSimpleString(ctx, "OK");
+    return REDISMODULE_OK;
+}
+
+int test_get_n_events(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    UNUSED(argv);
+    UNUSED(argc);
+    RedisModule_ReplyWithLongLong(ctx, n_events);
+    return REDISMODULE_OK;
+}
+
+int test_open_key_no_effects(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc<2) {
+        RedisModule_WrongArity(ctx);
+        return REDISMODULE_OK;
+    }
+
+    int supportedMode = RedisModule_GetOpenKeyModesAll();
+    if (!(supportedMode & REDISMODULE_READ) || !(supportedMode & REDISMODULE_OPEN_KEY_NOEFFECTS)) {
+        RedisModule_ReplyWithError(ctx, "OpenKey modes are not supported");
+        return REDISMODULE_OK;
+    }
+
+    RedisModuleKey *key = RedisModule_OpenKey(ctx, argv[1], REDISMODULE_READ | REDISMODULE_OPEN_KEY_NOEFFECTS);
+    if (!key) {
+        RedisModule_ReplyWithError(ctx, "key not found");
+        return REDISMODULE_OK;
+    }
+
+    RedisModule_CloseKey(key);
+    RedisModule_ReplyWithSimpleString(ctx, "OK");
+    return REDISMODULE_OK;
+}
+
 int test_call_generic(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
 {
     if (argc<2) {
@@ -460,6 +509,10 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
     if (RedisModule_Init(ctx,"misc",1,REDISMODULE_APIVER_1)== REDISMODULE_ERR)
         return REDISMODULE_ERR;
 
+    if(RedisModule_SubscribeToKeyspaceEvents(ctx, REDISMODULE_NOTIFY_KEY_MISS | REDISMODULE_NOTIFY_EXPIRED, KeySpace_NotificationModuleKeyMissExpired) != REDISMODULE_OK){
+        return REDISMODULE_ERR;
+    }
+
     if (RedisModule_CreateCommand(ctx,"test.call_generic", test_call_generic,"",0,0,0) == REDISMODULE_ERR)
         return REDISMODULE_ERR;
     if (RedisModule_CreateCommand(ctx,"test.call_info", test_call_info,"",0,0,0) == REDISMODULE_ERR)
@@ -507,6 +560,12 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
         return REDISMODULE_ERR;
     if (RedisModule_CreateCommand(ctx, "test.rm_call_replicate", test_rm_call_replicate,"allow-stale", 0, 0, 0) == REDISMODULE_ERR)
         return REDISMODULE_ERR;
+    if (RedisModule_CreateCommand(ctx, "test.silent_open_key", test_open_key_no_effects,"", 0, 0, 0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+    if (RedisModule_CreateCommand(ctx, "test.get_n_events", test_get_n_events,"", 0, 0, 0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+    if (RedisModule_CreateCommand(ctx, "test.clear_n_events", test_clear_n_events,"", 0, 0, 0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
 
     return REDISMODULE_OK;
 }

tests/unit/moduleapi/misc.tcl

@@ -485,6 +485,16 @@ start_server {tags {"modules"}} {
         assert_equal [r get x] $x
     }
 
+    test {test silent open key} {
+        r debug set-active-expire 0
+        r test.clear_n_events
+        r set x 1 PX 10
+        after 1000
+        # now the key has been expired, open it silently and make sure not event were fired.
+        assert_error {key not found} {r test.silent_open_key x}
+        assert_equal {0} [r test.get_n_events]
+    }
+
     test "Unload the module - misc" {
         assert_equal {OK} [r module unload misc]
     }