fix truncate

[jiangxinmeng1]

User description

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

issue #16987

What this PR does / why we need it:

comsume ErrInvalidTruncateLsn

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PR Type

Bug fix

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Description

• Added logging to indicate the start of the truncate process.
• Introduced error handling for ErrInvalidTruncateLsn using moerr.IsMoErrCode.
• Implemented retry logic for the truncate operation with additional logging for retries.
• Enhanced final log message to confirm successful truncation.

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Changes walkthrough 📝

	Relevant files
Bug fix	truncate.go Enhance truncate log service with error handling and logging pkg/vm/engine/tae/logstore/driver/logservicedriver/truncate.go Added logging for the start of the truncate process. Added error handling for ErrInvalidTruncateLsn using moerr.IsMoErrCode. Implemented retry logic for truncation with enhanced logging. Improved final log message to indicate successful truncation. +16/-2

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PR Reviewer Guide 🔍

⏱️ Estimated effort to review [1-5]	3
🧪 Relevant tests	No
🔒 Security concerns	No
⚡ Key issues to review	Possible Bug: The error handling for ErrInvalidTruncateLsn might not reset the error err to nil correctly if the condition truncatedLsn == lsn is not met, leading to unnecessary retries or a panic.
	Error Handling: The use of panic for handling errors in the retry logic could be replaced with more graceful error handling to avoid crashing the service.

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PR Code Suggestions ✨

Category	Suggestion	Score
Best practice	Use defer to ensure the cancel function is always called To ensure that the cancel function is always called, even if client.c.Truncate panics, consider using a defer statement right after the context is created. pkg/vm/engine/tae/logstore/driver/logservicedriver/truncate.go [77-79] ctx, cancel := context.WithTimeout(context.Background(), d.config.TruncateDuration) +defer cancel() err = client.c.Truncate(ctx, lsn) -cancel() Apply this suggestion Suggestion importance[1-10]: 9 Why: Using defer for the cancel function is a best practice in Go to ensure it is called even if the function exits unexpectedly, which improves the robustness of the code.	9
	Log the error before panicking to provide more context for debugging To improve error handling, consider logging the error before panicking, providing more context for debugging. pkg/vm/engine/tae/logstore/driver/logservicedriver/truncate.go [100-101] if err != nil { + logutil.Errorf("LogService Driver: Failed to truncate logservice with lsn %d, error: %v", lsn, err) panic(err) } Apply this suggestion Suggestion importance[1-10]: 8 Why: Logging errors before panicking is crucial for debugging and understanding the context of failures, making this a valuable improvement.	8
Maintainability	Extract retry logic into a separate function to avoid redundancy To avoid redundant code, extract the retry logic into a separate function and call it in both places where retry is needed. pkg/vm/engine/tae/logstore/driver/logservicedriver/truncate.go [87-98] err = RetryWithTimeout(d.config.RetryTimeout, func() (shouldReturn bool) { + return retryTruncate(client, lsn) +}) + +func retryTruncate(client ClientType, lsn uint64) bool { logutil.Infof("LogService Driver: retry truncate, lsn %d err is %v", lsn, err) ctx, cancel := context.WithTimeout(context.Background(), d.config.TruncateDuration) + defer cancel() err = client.c.Truncate(ctx, lsn) - cancel() if moerr.IsMoErrCode(err, moerr.ErrInvalidTruncateLsn) { - truncatedLsn := d.getLogserviceTruncate() - if truncatedLsn == lsn { + currentTruncatedLsn := d.getLogserviceTruncate() + if currentTruncatedLsn == lsn { err = nil } } return err == nil -}) +} Apply this suggestion Suggestion importance[1-10]: 7 Why: Extracting the retry logic into a separate function is a good practice for maintainability and code clarity, especially when the logic is complex and repeated.	7
Enhancement	Rename variable to improve readability To avoid potential confusion and improve readability, consider renaming the variable truncatedLsn to something more descriptive, such as currentTruncatedLsn. pkg/vm/engine/tae/logstore/driver/logservicedriver/truncate.go [81] -truncatedLsn := d.getLogserviceTruncate() +currentTruncatedLsn := d.getLogserviceTruncate() Apply this suggestion Suggestion importance[1-10]: 5 Why: Renaming truncatedLsn to currentTruncatedLsn could slightly improve readability by making the variable's purpose clearer, though it's a minor enhancement.	5