Avoid discarding transaction too early in queries #31
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Introduces the notion of implicit transactions: those started to execute one-off queries called on the Datastore. The goprocess for the iterator calls txn.Discard() on implicit transactions on closure. Needed after dgraph-io/badger@b1ad1e9.
ghost
assigned 
raulk
commented
Sep 12, 2018
| @@ -142,9 +152,10 @@ func (d *Datastore) Delete(key ds.Key) error { | |||
| } | |||
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| func (d *Datastore) Query(q dsq.Query) (dsq.Results, error) { | |||
| txn := d.NewTransaction(true) | |||
| defer txn.Discard() | |||
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This defer is problematic with badger master, as it discards the txn while the iterator is active.
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This is the error this PR solves:
panic: Unclosed iterator at time of Txn.Discard. [recovered]
panic: Unclosed iterator at time of Txn.Discard.
bigs
approved these changes
Sep 12, 2018
| @@ -79,11 +83,17 @@ func NewDatastore(path string, options *Options) (*Datastore, error) { | |||
| // can be mutated without incurring changes to the underlying Datastore until | |||
| // the transaction is Committed. | |||
| func (d *Datastore) NewTransaction(readOnly bool) ds.Txn { | |||
| return &txn{d.DB.NewTransaction(!readOnly)} | |||
| return &txn{d.DB.NewTransaction(!readOnly), false} | |||
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now that we have more than one value in the struct, let's address them by name
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Oops, I merged before addressing this. Worth opening another PR?
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maybe just leave a todo for yourself! i think it's fine.
magik6k
approved these changes
Sep 12, 2018
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Tests against badger master are failing because of dgraph-io/badger@b1ad1e9
As per that commit, badger now fails if a transaction holding an iterator is discarded while the iterator is still active.
This commit tracks implicit transactions: those created solely to execute
one-off queries called on the
Datastore. The goprocess for the iterator now callstxn.Discard()on implicit transactions on closure.