SequentialWriter::open failing to create a bag file

[Marwan99]

Description

I am trying to use the API to save a message to a bag.
I am using rosbag2_cpp::writers::SequentialWriter to open a bag (which does not exist yet, expecting the API to create it) then write to it.

Expected Behavior

Creation of a bag file in the URI specified on the use of SequentialWriter::open.

Actual Behavior

No bag file is being created. I am getting the error messages below and the code stops.

[rosbag2_storage]: Could not open 'my_bag/my_bag_0' with 'sqlite3'. Error: Failed to setup storage. Error: Could not read-write open database. SQLite error (14): unable to open database file
[ERROR] [1593304125.490127311] [rosbag2_storage]: Could not load/open plugin with storage id 'sqlite3'.
unknown file: Failure C++ exception with description "No storage could be initialized. Abort"

To Reproduce

That's part of the code I am using, bag->open(...) is what cause all the error messages:

rosbag2_cpp::StorageOptions storage_options = rosbag2_cpp::StorageOptions{};
storage_options.uri = "my_bag";
storage_options.storage_id = "sqlite3";

auto bag = std::make_unique<rosbag2_cpp::writers::SequentialWriter>();
bag->open(storage_options, {"rmw_format", "rmw_format"});

System

• OS: Ubuntu 18.04
• ROS 2 Distro: Rolling
• Version: master a4d49db

Additional context

I have dug a bit into the code, it seems to me that SqliteWrapper::SqliteWrapper is the method that is supposed to create a db3 file in whatever URI passed to. I did some tests and this function can only create db3 files in existing directories and will fail to create a db if the directory doesn't exist.

rosbag2/rosbag2_storage_default_plugins/src/rosbag2_storage_default_plugins/sqlite/sqlite_wrapper.cpp

Lines 50 to 52 in a4d49db

	int rc = sqlite3_open_v2(
	uri.c_str(), &db_ptr,
	SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_NOMUTEX, nullptr);

I couldn't see a place where non-existent URIs get created(maybe I am missing something). I think the resolution for this problem could be checking the existence of the URI and creating it if it doesn't exist, this can maybe be performed in this function:

rosbag2/rosbag2_cpp/src/rosbag2_cpp/writers/sequential_writer.cpp

Line 36 in a4d49db

std::string format_storage_uri(const std::string & base_folder, uint64_t storage_count)

Apologies if my problem analysis is wrong (likely :-)), Please let me know if I need to provide any extra info.
Thanks in advance!

[Karsten1987]

You've analyzed the problem absolutely correctly. It's currently the ros2bag command line interface which is responsible for creating the directory: https://github.com/ros2/rosbag2/blob/master/ros2bag/ros2bag/verb/record.py#L111

I guess by now we have enough functionality in rcutils/rcpputils to integrate that work into rosbag2_cpp. So thanks a lot for opening the discussion here.

[Karsten1987]

closed via #450