Always reuse transaction #22362
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Always reuse transaction #22362
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lunny
approved these changes
Jan 7, 2023
Codecov Report
@@ Coverage Diff @@
## main #22362 +/- ##
=========================================
+ Coverage 0 48.13% +48.13%
=========================================
Files 0 1046 +1046
Lines 0 142384 +142384
=========================================
+ Hits 0 68535 +68535
- Misses 0 65667 +65667
- Partials 0 8182 +8182
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delvh
approved these changes
Jan 7, 2023
| // halfCommitter is a wrapper of Committer. | ||
| // It can be closed early, but can't be committed early, it is useful for reusing a transaction. | ||
| type halfCommitter struct { | ||
| Committer | ||
| } | ||
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|
||
| func (*halfCommitter) Commit() error { | ||
| // do nothing | ||
| return nil | ||
| } | ||
|
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| // TxContext represents a transaction Context, | ||
| // it will reuse the existing transaction in the parent context or create a new one. | ||
| func TxContext(parentCtx context.Context) (*Context, Committer, error) { | ||
| if InTransaction(parentCtx) { | ||
| return nil, nil, ErrAlreadyInTransaction | ||
| if sess, ok := inTransaction(parentCtx); ok { | ||
| return newContext(parentCtx, sess, true), &halfCommitter{Committer: sess}, nil |
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Hmm, I'm not sure if this is the definitive answer.
I'll accept it for now, but I think it would be better if Commit would still be possible with the behavior that it opens a new transaction afterward.
This was referenced Jan 8, 2023
zjjhot
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Jan 9, 2023
* upstream/main: Replace `can not` with `cannot` (go-gitea#22372) Fix set system setting failure once it cached (go-gitea#22333) Bump json5 from 1.0.1 to 1.0.2 (go-gitea#22365) Always reuse transaction (go-gitea#22362) make /{username}.png redirect to user/org avatar (go-gitea#22356) Remove old HookEventType (go-gitea#22358)
lunny
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Jan 9, 2023
After #22362, we can feel free to use transactions without `db.DefaultContext`. And there are still lots of models using `db.DefaultContext`, I think we should refactor them carefully and one by one. Co-authored-by: Lunny Xiao <[email protected]>
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techknowlogick
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Jan 9, 2023
Related to #22362. I overlooked that there's always `committer.Close()`, like: ```go ctx, committer, err := db.TxContext(db.DefaultContext) if err != nil { return nil } defer committer.Close() // ... if err != nil { return nil } // ... return committer.Commit() ``` So the `Close` of `halfCommitter` should ignore `commit and close`, it's not a rollback. See: [Why `halfCommitter` and `WithTx` should rollback IMMEDIATELY or commit LATER](#22366 (comment)). Co-authored-by: techknowlogick <[email protected]>
fsologureng
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Jan 24, 2023
fsologureng
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Jan 24, 2023
After go-gitea#22362, we can feel free to use transactions without `db.DefaultContext`. And there are still lots of models using `db.DefaultContext`, I think we should refactor them carefully and one by one. Co-authored-by: Lunny Xiao <[email protected]>
fsologureng
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Jan 24, 2023
Related to go-gitea#22362. I overlooked that there's always `committer.Close()`, like: ```go ctx, committer, err := db.TxContext(db.DefaultContext) if err != nil { return nil } defer committer.Close() // ... if err != nil { return nil } // ... return committer.Commit() ``` So the `Close` of `halfCommitter` should ignore `commit and close`, it's not a rollback. See: [Why `halfCommitter` and `WithTx` should rollback IMMEDIATELY or commit LATER](go-gitea#22366 (comment)). Co-authored-by: techknowlogick <[email protected]>
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I don't see any cases where we have to create a new transaction instead of reusing the transaction in context. So:
WithTxandAutoTxtoWithTx, and it always reuses the transaction if it exists;TxContextreuse the transaction if it exists, and it will returnhalfCommitterwhen reusing.halfCommitterimplementsCommitter, but it does nothing when committing, so it's possible to close a reused transaction early, but impossible to commit it early.ErrAlreadyInTransaction, I don't see anyerrors.Is(err, db.ErrAlreadyInTransaction), and we don't need it any longer.After this, we can refactor
db.TxContext(db.DefaultContext)todb.TxContext(ctx)safely, and feel free to usedb.TxContextordb.WithTxin (almost) any functions as long as there is actx. I know it's better to usedb.WithTxinstead ofdb.TxContext, but for refactoring, I don't think so, it will cause lots of lines to change because an anonymous function is required.