fix(WriteAPIBlocking): properly return error from flush()

[danielorbach]

Commit a9c1e37 introduced a bug, where a successful Flush returns a non-nil error because the internal function (w.service.WriteBatch) returns a concrete pointer and not an error.

Closes #360

This bug is not present without Batching because the return value of WriteBatch() is properly checked before returning from the function writeAPIBlocking.write(). This code path is skipped by delegating the work to writeAPIBlocking.flush() instead.

func (w *writeAPIBlocking) write(ctx context.Context, line string) error {
	if atomic.LoadInt32(&w.batching) > 0 {
		w.mu.Lock()
		defer w.mu.Unlock()
		w.batch = append(w.batch, line)
		if len(w.batch) == int(w.writeOptions.BatchSize()) {
			return w.flush(ctx)
		} else {
			return nil
		}
	}
	err := w.service.WriteBatch(ctx, iwrite.NewBatch(line, w.writeOptions.MaxRetryTime()))
	if err != nil {
		return err
	}
	return nil
}

// flush is unsychronized helper for creating and sending batch
// Must be called from synchronized block
func (w *writeAPIBlocking) flush(ctx context.Context) error {
	if len(w.batch) > 0 {
		body := strings.Join(w.batch, "\n")
		w.batch = w.batch[:0]
		b := iwrite.NewBatch(body, w.writeOptions.MaxRetryTime())
		return w.service.WriteBatch(ctx, b)
	}
	return nil
}

Proposed Changes

check the concrete type for a nil pointer (of type *http2.Error) otherwise return an explicit nil error.

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• Tests pass
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[telegraf-tiger]

Thanks so much for the pull request!
🤝 ✒️ Just a reminder that the CLA has not yet been signed, and we'll need it before merging. Please sign the CLA when you get a chance, then post a comment here saying !signed-cla

[codecov-commenter]

Codecov Report

Base: 92.36% // Head: 92.28% // Decreases project coverage by -0.08% ⚠️

Coverage data is based on head (0292c61) compared to base (388612e).
Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #359      +/-   ##
==========================================
- Coverage   92.36%   92.28%   -0.09%     
==========================================
  Files          23       23              
  Lines        2227     2228       +1     
==========================================
- Hits         2057     2056       -1     
- Misses        130      131       +1     
- Partials       40       41       +1     

Impacted Files	Coverage Δ
api/writeAPIBlocking.go	87.27% <0.00%> (-3.47%)	⬇️
version.go	100.00% <ø> (ø)

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[danielorbach]

Thanks so much for the pull request! 🤝 ✒️ Just a reminder that the CLA has not yet been signed, and we'll need it before merging. Please sign the CLA when you get a chance, then post a comment here saying !signed-cla

!signed-cla

[vlastahajek]

@danielorbach, good point. Thanks for the PR!

[danielorbach]

@vlastahajek Please see the updated description, related Issue (#360) and new commit (0292c61).

Let me know if I should add anything else.

[powersj]

@vlastahajek are you good with the update?

@danielorbach would you be willing to add an entry to the change log as well? That way we can grab this for the release this week.

Thanks!

[danielorbach]

@vlastahajek are you good with the update?

@danielorbach would you be willing to add an entry to the change log as well? That way we can grab this for the release this week.

Thanks!

Sorry @powersj I haven't had the time to do it before this PR has been merged.
Would you like me to open another Pull Request for that?

[vlastahajek]

No worries, I've already added the entry.