Function RM_HoldString

src/module.cpp:1328–1365

* This function can be used instead of RedisModule_RetainString(). * The main difference between the two is that this function will always * succeed, whereas RedisModule_RetainString() may fail because of an * assertion. * * The function returns a pointer to RedisModuleString, which is owned * by the caller. It requires a call to RedisModule_FreeString() to free * the string when automatic memory

* It is possible to call this function with a NULL context.
*/
RedisModuleString* RM_HoldString(RedisModuleCtx *ctx, RedisModuleString *str) {
    if (str->getrefcount(std::memory_order_relaxed) == OBJ_STATIC_REFCOUNT) {
        return RM_CreateStringFromString(ctx, str);
    }

    incrRefCount(str);
    if (ctx != NULL) {
        /*
         * Put the str in the auto memory management of the ctx.
         * It might already be there, in this case, the ref count will
         * be 2 and we will decrease the ref count twice and free the
         * object in the auto memory free function.
         *
         * Why we can not do the same trick of just remove the object
         * from the auto memory (like in RM_RetainString)?
         * This code shows the issue:
         *
         * RM_AutoMemory(ctx);
         * str1 = RM_CreateString(ctx, "test", 4);
         * str2 = RM_HoldString(ctx, str1);
         * RM_FreeString(str1);
         * RM_FreeString(str2);
         *
         * If after the RM_HoldString we would just remove the string from
         * the auto memory, this example will cause access to a freed memory
         * on 'RM_FreeString(str2);' because the String will be free
         * on 'RM_FreeString(str1);'.
         *
         * So it's safer to just increase the ref count
         * and add the String to auto memory again.
         *
         * The limitation is that it is not possible to use RedisModule_StringAppendBuffer
         * on the String.
         */
        autoMemoryAdd(ctx,REDISMODULE_AM_STRING,str);
    }
    return str;
}

/* Given a string module object, this function returns the string pointer
 * and length of the string. The returned pointer and length should only