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make view protection optimistic again, as there is a race window

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This commit is contained in:
vyzo 2021-07-09 15:41:10 +03:00
parent da0feb3fa4
commit 095d7427ba
1 changed files with 13 additions and 17 deletions
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30
blockstore/splitstore/splitstore.go
View File

@ -432,24 +432,20 @@ func (s *SplitStore) View(cid cid.Cid, cb func([]byte) error) error {
return cb(data) return cb(data)
} }
err := s.hot.View(cid, // views are (optimistically) protected two-fold:
func(data []byte) error { // - if there is an active transaction, then the reference is protected.
// views are protected two-fold: // - if there is no active transaction, active views are tracked in a
// - if there is an active transaction, then the reference is protected. // wait group and compaction is inhibited from starting until they
// - if there is no active transaction, active views are tracked in a // have all completed. this is necessary to ensure that a (very) long-running
// wait group and compaction is inhibited from starting until they // view can't have its data pointer deleted, which would be catastrophic.
// have all completed. this is necessary to ensure that a (very) long-running // Note that we can't just RLock for the duration of the view, as this could
// view can't have its data pointer deleted, which would be catastrophic. // lead to deadlock with recursive views.
// Note that we can't just RLock for the duration of the view, as this could wg := s.protectView(cid)
// lead to deadlock with recursive views. if wg != nil {
wg := s.protectView(cid) defer wg.Done()
if wg != nil { }
defer wg.Done()
}
return cb(data)
})
err := s.hot.View(cid, cb)
switch err { switch err {
case bstore.ErrNotFound: case bstore.ErrNotFound:
if s.debug != nil { if s.debug != nil {