Modules: Hash type API WIP #2.

src/module.c

@@ -1612,8 +1612,58 @@ int RM_HashSet(RedisModuleKey *key, int flags, ...) {
  *
  * The function returns REDISMODULE_OK on success and REDISMODULE_ERR if
  * the key is not an hash value.
+ *
+ * Memory management:
+ *
+ * The returned RedisModuleString objects should be released with
+ * RedisModule_FreeString(), or by enabling automatic memory management.
  */
 int RM_HashGet(RedisModuleKey *key, int flags, ...) {
+    va_list ap;
+    if (key->value && key->value->type != OBJ_HASH) return REDISMODULE_ERR;
+
+    va_start(ap, flags);
+    while(1) {
+        RedisModuleString *field, **valueptr;
+        int *existsptr;
+        /* Get the field object and the value pointer to pointer. */
+        if (flags & REDISMODULE_HGET_CFIELDS) {
+            char *cfield = va_arg(ap,char*);
+            if (cfield == NULL) break;
+            field = createRawStringObject(cfield,strlen(cfield));
+        } else {
+            field = va_arg(ap,RedisModuleString*);
+            if (field == NULL) break;
+        }
+
+        /* Query the hash for existence or value object. */
+        if (flags & REDISMODULE_HGET_EXISTS) {
+            existsptr = va_arg(ap,int*);
+            if (key->value)
+                *existsptr = hashTypeExists(key->value,field->ptr);
+            else
+                *existsptr = 0;
+        } else {
+            valueptr = va_arg(ap,RedisModuleString**);
+            if (key->value) {
+                *valueptr = hashTypeGetValueObject(key->value,field->ptr);
+                if (*valueptr) {
+                    robj *decoded = getDecodedObject(*valueptr);
+                    decrRefCount(*valueptr);
+                    *valueptr = decoded;
+                }
+                if (*valueptr)
+                    autoMemoryAdd(key->ctx,REDISMODULE_AM_STRING,*valueptr);
+            } else {
+                *valueptr = NULL;
+            }
+        }
+
+        /* Cleanup */
+        if (flags & REDISMODULE_HSET_CFIELDS) decrRefCount(field);
+    }
+    va_end(ap);
+    return REDISMODULE_ERR;
 }
 
 /* --------------------------------------------------------------------------
@@ -2078,6 +2128,7 @@ void moduleRegisterCoreAPI(void) {
     REGISTER_API(ZsetRangePrev);
     REGISTER_API(ZsetRangeEndReached);
     REGISTER_API(HashSet);
+    REGISTER_API(HashGet);
 }
 
 /* Global initialization at Redis startup. */

src/modules/helloworld.c

@@ -438,10 +438,13 @@ int HelloHCopy_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int a
         return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
     }
 
-    /* XXX modify me. */
+    /* Get the old field value. */
-    RedisModule_HashSet(key,REDISMODULE_HSET_NONE,argv[2],argv[3],NULL);
+    RedisModuleString *oldval;
-    RedisModule_HashSet(key,REDISMODULE_HSET_CFIELDS,"foo",argv[3],NULL);
+    RedisModule_HashGet(key,REDISMODULE_HGET_NONE,argv[2],&oldval,NULL);
-    RedisModule_ReplyWithLongLong(ctx,0);
+    if (oldval) {
+        RedisModule_HashSet(key,REDISMODULE_HSET_NONE,argv[3],oldval,NULL);
+    }
+    RedisModule_ReplyWithLongLong(ctx,oldval != NULL);
     return REDISMODULE_OK;
 }
 

src/redismodule.h

@@ -150,6 +150,7 @@ int REDISMODULE_API_FUNC(RedisModule_ZsetRangeNext)(RedisModuleKey *key);
 int REDISMODULE_API_FUNC(RedisModule_ZsetRangePrev)(RedisModuleKey *key);
 int REDISMODULE_API_FUNC(RedisModule_ZsetRangeEndReached)(RedisModuleKey *key);
 int REDISMODULE_API_FUNC(RedisModule_HashSet)(RedisModuleKey *key, int flags, ...);
+int REDISMODULE_API_FUNC(RedisModule_HashGet)(RedisModuleKey *key, int flags, ...);
 
 /* This is included inline inside each Redis module. */
 static int RedisModule_Init(RedisModuleCtx *ctx, const char *name, int ver, int apiver) {
@@ -215,6 +216,7 @@ static int RedisModule_Init(RedisModuleCtx *ctx, const char *name, int ver, int
     REDISMODULE_GET_API(ZsetRangePrev);
     REDISMODULE_GET_API(ZsetRangeEndReached);
     REDISMODULE_GET_API(HashSet);
+    REDISMODULE_GET_API(HashGet);
 
     RedisModule_SetModuleAttribs(ctx,name,ver,apiver);
     return REDISMODULE_OK;