int aws_mqtt_topic_tree_transaction_remove()

in source/topic_tree.c [686:782]

• 72 lines of code
• 11 McCabe index (conditional complexity)

int aws_mqtt_topic_tree_transaction_remove(
    struct aws_mqtt_topic_tree *tree,
    struct aws_array_list *transaction,
    const struct aws_byte_cursor *topic_filter,
    void **old_userdata) {

    AWS_PRECONDITION(tree);
    AWS_PRECONDITION(transaction);
    AWS_PRECONDITION(topic_filter);

    AWS_LOGF_DEBUG(
        AWS_LS_MQTT_TOPIC_TREE,
        "tree=%p: Removing topic filter \"" PRInSTR "\" from topic tree",
        (void *)tree,
        AWS_BYTE_CURSOR_PRI(*topic_filter));

    /* Initialize output parameter to a safe default */
    if (old_userdata) {
        *old_userdata = NULL;
    }

    /* Default to error because that's what handle_error will do in all cases except node not found */
    int result = AWS_OP_ERR;
    struct topic_tree_action *action = s_topic_tree_action_create(transaction);
    if (!action) {
        return AWS_OP_ERR;
    }

    struct aws_array_list sub_topic_parts;
    AWS_ZERO_STRUCT(sub_topic_parts);

    if (aws_array_list_init_dynamic(&sub_topic_parts, tree->allocator, 1, sizeof(struct aws_byte_cursor))) {
        AWS_LOGF_ERROR(AWS_LS_MQTT_TOPIC_TREE, "tree=%p: Failed to initialize topic parts array", (void *)tree);
        goto handle_error;
    }

    if (aws_byte_cursor_split_on_char(topic_filter, '/', &sub_topic_parts)) {
        AWS_LOGF_ERROR(AWS_LS_MQTT_TOPIC_TREE, "tree=%p: Failed to split topic filter", (void *)tree);
        goto handle_error;
    }
    const size_t sub_parts_len = aws_array_list_length(&sub_topic_parts);
    if (!sub_parts_len) {
        AWS_LOGF_ERROR(AWS_LS_MQTT_TOPIC_TREE, "tree=%p: Failed to get topic parts length", (void *)tree);
        goto handle_error;
    }
    s_topic_tree_action_to_remove(action, tree->allocator, sub_parts_len);

    struct aws_mqtt_topic_node *current = tree->root;
    if (aws_array_list_push_back(&action->to_remove, &current)) {
        AWS_LOGF_ERROR(AWS_LS_MQTT_TOPIC_TREE, "tree=%p: Failed to insert root node into to_remove list", (void *)tree);
        goto handle_error;
    }

    for (size_t i = 0; i < sub_parts_len; ++i) {

        /* Get the current topic part */
        struct aws_byte_cursor *sub_part = NULL;
        aws_array_list_get_at_ptr(&sub_topic_parts, (void **)&sub_part, i);

        /* Find mid-node */
        struct aws_hash_element *elem = NULL;
        aws_hash_table_find(&current->subtopics, sub_part, &elem);
        if (elem) {
            /* If the node exists, just traverse it */
            current = elem->value;
            if (aws_array_list_push_back(&action->to_remove, &current)) {
                AWS_LOGF_ERROR(
                    AWS_LS_MQTT_TOPIC_TREE, "tree=%p: Failed to insert topic node into to_remove list", (void *)tree);
                goto handle_error;
            }
        } else {
            /* If not, abandon ship */
            goto handle_not_found;
        }
    }

    action->node_to_update = current;

    aws_array_list_clean_up(&sub_topic_parts);

    if (old_userdata) {
        *old_userdata = current->userdata;
    }

    return AWS_OP_SUCCESS;

handle_not_found:
    result = AWS_OP_SUCCESS;

handle_error:
    aws_array_list_clean_up(&sub_topic_parts);

    s_topic_tree_action_destroy(action);
    aws_array_list_pop_back(transaction);

    return result;
}