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lock fragment to compute rows

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If you don't hold the fragment lock when computing rows, it's
pretty reasonable for other stuff to be able to modify it -- which
could invalidate or race the enumeration.

Some calls to f.rows were being made with the lock held, others
weren't, so we introduce `f.unprotectedRows` which has the obvious
semantics. (Without which this looked great except that several
of the tests deadlocked.)
This commit is contained in:
Seebs 2019-06-26 10:57:31 -05:00 • committed by Matt Jaffee
parent cb50a5a48b
commit 5e3d01febe
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1 changed files with 13 additions and 4 deletions
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17
fragment.go
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@ -2669,6 +2669,13 @@ func filterWithRows(rows []uint64) rowFilter {
// this container have been processed. The rows accumulated up to this point
// (including this row if all filters passed) will be returned.
func (f *fragment) rows(start uint64, filters ...rowFilter) []uint64 {
f.mu.Lock()
defer f.mu.Unlock()
return f.unprotectedRows(start, filters...)
}
// unprotectedRows calls rows without grabbing the mutex.
func (f *fragment) unprotectedRows(start uint64, filters ...rowFilter) []uint64 {
startKey := rowToKey(start)
i, _ := f.storage.Containers.Iterator(startKey)
rows := make([]uint64, 0)
@ -3096,9 +3103,10 @@ func newRowsVector(f *fragment) *rowsVector {
// Get returns the rowID associated to the given colID.
// Additionally, it returns true if a value was found,
// otherwise it returns false.
// otherwise it returns false. Ensure that you already
// have the mutex before calling this.
func (v *rowsVector) Get(colID uint64) (uint64, bool, error) {
rows := v.f.rows(0, filterColumn(colID))
rows := v.f.unprotectedRows(0, filterColumn(colID))
if len(rows) > 1 {
return 0, false, errors.New("found multiple row values for column")
} else if len(rows) == 1 {
@ -3129,9 +3137,10 @@ func newBoolVector(f *fragment) *boolVector {
// Get returns the rowID associated to the given colID.
// Additionally, it returns true if a value was found,
// otherwise it returns false.
// otherwise it returns false. Ensure that you already
// have the fragment mutex before calling this.
func (v *boolVector) Get(colID uint64) (uint64, bool, error) {
rows := v.f.rows(0, filterColumn(colID))
rows := v.f.unprotectedRows(0, filterColumn(colID))
if len(rows) > 1 {
return 0, false, errors.New("found multiple row values for column")
} else if len(rows) == 1 {