feat!: use replace_urls service instead of runtime property [BD-13]

[Agrendalath]

Description

BREAKING CHANGE: This breaks Maple compatibility.

Using the property of runtime is deprecated. It also breaks Block Structures when the ModuleSystem is unified with DescriptorSystem.

Supporting information

Related PR: openedx/edx-platform#31472

Testing instructions (optional)

1. Create a course with two DnDv2 XBlocks and complete the first one.
2. Replace the block_id and run the following snippet:

from lms.djangoapps.course_blocks.api import get_course_blocks
from opaque_keys.edx.locator import BlockUsageLocator

u = User.objects.get(username='edx')
key = BlockUsageLocator.from_string('block_id')
block_data = get_course_blocks(u, key)

3. Visit the /dashboard. This will trigger the code to find the resume URL and attempt to re-generate Block Structures.

Deadline

Before openedx/edx-platform#31472.

Author's notes

A quick summary: the Block Structures are used for caching the structure of the Course Outline page (stored as files in S3). The caching operation has a limited runtime for XBlocks (it does not include all available runtime services). However, when the completion tracking is enabled, this still needs to generate student-specific data for the most recently completed XBlock to perform some calculations. There is a lot of redundancy and a massive room for optimizations, but there are enough layers to make a whole new epic of out debugging it.

Generating student data of DnDv2 replaces static links, but the relevant service is unavailable. Therefore, we ignore this step - it does not affect the result. As for why this is happening after merging the ModuleSystem and DescriptorSystem - previously, the caching operation was relying directly on the DescriptorSystem, which didn't have the replace_urls attribute. We still need to keep it in the ModuleSystem for backward compatibility. As the ModuleSystem and DescriptorSystem become the same class in the mentioned PR, it will now have the replace_urls attribute, which makes the logic in DnDv2 invalid.

We could do a few different things - e.g., move the replacing static links operation to another part of the DnDv2 (or make it lazy), but this would break tons of tests, making it a more significant change. Given the limited time and budget here, this seemed like the most straightforward fix to me.

[openedx-webhooks]

Thanks for the pull request, @Agrendalath!

When this pull request is ready, tag your edX technical lead.

[openedx-webhooks]

Thanks for the pull request, @Agrendalath!

This is currently a draft pull request. When it is ready for our review and all tests are green, click "Ready for Review", or remove "WIP" from the title, as appropriate.

[Agrendalath]

Maple is an old release, so I didn't bother bumping the major version number. Let me know if we should do this, though.

[Cup0fCoffee]

@Agrendalath Since we are breaking the compatibility with Maple, and self.runtime.replace_urls is being deprecated, do you think we can remove this section as well?

[Cup0fCoffee]

👍 Other than this comment, everything else looks fine.

• I tested this: ran the testing steps
• I read through the code

[openedx-webhooks]

@Agrendalath 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.

[openedx-webhooks]

@Agrendalath 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.