fix(client): resource leak in SSEClient.SendRequest()

[cryo-zd]

  Currently, func SendRequest() in SSE client has potential risk of not removing the responseChan for request forever because func SendRequest create responseChan at the very beginning, and the following situations will cause resource leak in our program:

1. we fail to create a http.Request object when we call func http.NewRequestWithContext
2. http.Request fails to send request to MCPserver when we call c.httpClient.Do(req)
3. the response status code that MCPServer returns ≠ http.StatusOK/http.StatusAccepted

How about using defer to remove responseChan ?
  Note func SSE.handleSSEEvent will finally remove the channel for this request after we receive data from MCPServer and write back data to responseChan . Though deleting a key from a map for twice is ok, it is not efficient in concurrent scenario because we have to lock the exclusive mutex in SSEClient every time when we want to modify SSEClient.responses and defer is redundant but also tries to lock when every thing goes well( actually, this is most of the cases will happen, the boundary cases mentioned above is rather low possible)

Summary by CodeRabbit

• Refactor
  • Improved internal request handling for better clarity and resource management.
  • Enhanced reliability by ensuring response channels are consistently cleaned up to prevent resource leaks.

[coderabbitai]

Walkthrough

The SendRequest method in the client/transport/sse.go file was refactored to reorder operations and improve resource management. Request marshaling now occurs before HTTP request creation, which is done in a single call. HTTP headers, including custom ones, are set prior to registering the response channel. A new helper function was introduced to safely remove the response channel from the internal map under lock, and this cleanup is consistently invoked on all early exit points after channel registration. Error message formatting for failed HTTP responses was consolidated. No changes were made to public interfaces.

Changes

File(s)	Change Summary
client/transport/sse.go	Refactored SendRequest to reorder operations, add a helper for response channel cleanup, ensure consistent cleanup on failure or cancellation, and streamline error handling. No changes to public interfaces.

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 4b63bff and 24e8db9.

📒 Files selected for processing (1)

• client/transport/sse.go (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• client/transport/sse.go

✨ 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 generate sequence diagram to generate a sequence diagram of the changes in 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.

CodeRabbit Configuration File (.coderabbit.yaml)

• You can programmatically configure CodeRabbit by adding a .coderabbit.yaml file to the root of your repository.
• Please see the configuration documentation for more information.
• If your editor has YAML language server enabled, you can add the path at the top of this file to enable auto-completion and validation: # yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json

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.