Fix some places of optimistic lock contract violation

[laurynas-biveinis]

Make sure that for node type reads, there is a lock check between the type read
and acting on that type. Remove an assert that acts on the node type without a
lock check.

Summary by CodeRabbit

• Chores
  • Enhanced the system’s internal concurrency checks and error handling to improve overall stability during simultaneous operations. These improvements help ensure smoother performance under heavy usage without altering any visible features or public interfaces.

[coderabbitai]

Walkthrough

This change modifies the optimistic locking logic in the olc_db class within olc_art.hpp. The assertion that a node was not a leaf in try_push was removed and replaced by a check ensuring the read critical section is valid. Additional validations have been added in methods such as try_get, try_insert, try_remove, and iterator functions. Error handling has been refined with LCOV annotations to exclude specific lines from coverage, ensuring that operations only continue when the critical sections validate successfully.

Changes

File	Change Summary
olc_art.hpp	Removed the leaf node assertion in try_push; added a new rcs.check() in try_push; introduced additional critical section validity checks in try_get, try_insert, try_remove, try_next, try_prior, and try_seek; enhanced error handling with LCOV annotations.

Sequence Diagram(s)

sequenceDiagram
    participant Client as Client
    participant DB as olc_db
    participant RCS as ReadCriticalSection

    Client->>DB: call try_push(node)
    DB->>RCS: rcs.check()
    alt RCS check fails
        DB-->>Client: return false
    else RCS check passes
        DB-->>Client: proceed with push
    end

Loading

Possibly related PRs

• laurynas-biveinis/unodb#645: Addresses similar enhancements in read critical section handling, focusing on const-correctness and improved error handling.

Poem

In the realm of code so stark,
Critical checks now light the dark.
Gone are assertions that once did bind,
RCS stands guard, precise and aligned.
Threads march on—errors left behind!

(May your locks be ever optimistic!)

---

📜 Recent review details

Configuration used: .coderabbit.yaml
Review profile: ASSERTIVE
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 2c6be83 and 41fcf00.

📒 Files selected for processing (1)

• olc_art.hpp (9 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (10)

• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis
• GitHub Check: Codacy Static Code Analysis

🔇 Additional comments (2)

olc_art.hpp (2)

457-458: Extra .check() validation looks correct.
These lines introduce a validity check on the read critical section before pushing an entry onto the stack, which is consistent with the optimistic locking approach. No issues found.

---

1862-1865: Early return upon lock restart is well-aligned with concurrency flow.
This block correctly handles a must-restart scenario by returning early (empty optional). It keeps the logic consistent with the rest of the optimistic lock checks.

✨ Finishing Touches

• 📝 Generate Docstrings

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

🪧 Tips

Chat

There are 3 ways to chat with CodeRabbit:

• Review comments: Directly reply to a review comment made by CodeRabbit. Example:
  • I pushed a fix in commit <commit_id>, please review it.
  • Generate unit testing code for this file.
  • Open a follow-up GitHub issue for this discussion.
• Files and specific lines of code (under the "Files changed" tab): Tag @coderabbitai in a new review comment at the desired location with your query. Examples:
  • @coderabbitai generate unit testing code for this file.
  • @coderabbitai modularize this function.
• PR comments: Tag @coderabbitai in a new PR comment to ask questions about the PR branch. For the best results, please provide a very specific query, as very limited context is provided in this mode. Examples:
  • @coderabbitai gather interesting stats about this repository and render them as a table. Additionally, render a pie chart showing the language distribution in the codebase.
  • @coderabbitai read src/utils.ts and generate unit testing code.
  • @coderabbitai read the files in the src/scheduler package and generate a class diagram using mermaid and a README in the markdown format.
  • @coderabbitai help me debug CodeRabbit configuration file.

Note: Be mindful of the bot's finite context window. It's strongly recommended to break down tasks such as reading entire modules into smaller chunks. For a focused discussion, use review comments to chat about specific files and their changes, instead of using the PR comments.

CodeRabbit Commands (Invoked using PR comments)

• @coderabbitai pause to pause the reviews on a PR.
• @coderabbitai resume to resume the paused reviews.
• @coderabbitai review to trigger an incremental review. This is useful when automatic reviews are disabled for the repository.
• @coderabbitai full review to do a full review from scratch and review all the files again.
• @coderabbitai summary to regenerate the summary of the PR.
• @coderabbitai generate docstrings to generate docstrings for this PR.
• @coderabbitai resolve resolve all the CodeRabbit review comments.
• @coderabbitai configuration to show the current CodeRabbit configuration for the repository.
• @coderabbitai help to get help.

Other keywords and placeholders

• Add @coderabbitai ignore anywhere in the PR description to prevent this PR from being reviewed.
• Add @coderabbitai summary to generate the high-level summary at a specific location in the PR description.
• Add @coderabbitai anywhere in the PR title to generate the title automatically.

Documentation and Community

• Visit our Documentation for detailed information on how to use CodeRabbit.
• Join our Discord Community to get help, request features, and share feedback.
• Follow us on X/Twitter for updates and announcements.