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mvcc: reduce count-only range overhead

release-3.5
tangcong 2020-04-09 23:50:17 +08:00
parent 7eae024ead
commit 730f3f1d78
3 changed files with 28 additions and 4 deletions
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18
mvcc/index.go
View File

@ -26,6 +26,7 @@ type index interface {
Get(key []byte, atRev int64) (rev, created revision, ver int64, err error)
Range(key, end []byte, atRev int64) ([][]byte, []revision)
Revisions(key, end []byte, atRev int64) []revision
CountRevisions(key, end []byte, atRev int64) int
Put(key []byte, rev revision)
Tombstone(key []byte, rev revision) error
RangeSince(key, end []byte, rev int64) []revision
@ -119,6 +120,23 @@ func (ti *treeIndex) Revisions(key, end []byte, atRev int64) (revs []revision) {
return revs
}
func (ti *treeIndex) CountRevisions(key, end []byte, atRev int64) int {
if end == nil {
_, _, _, err := ti.Get(key, atRev)
if err != nil {
return 0
}
return 1
}
total := 0
ti.visit(key, end, func(ki *keyIndex) {
if _, _, _, err := ki.get(ti.lg, atRev); err == nil {
total++
}
})
return total
}
func (ti *treeIndex) Range(key, end []byte, atRev int64) (keys [][]byte, revs []revision) {
if end == nil {
rev, _, _, err := ti.Get(key, atRev)

5
mvcc/kvstore_test.go
View File

@ -941,6 +941,11 @@ func (i *fakeIndex) Revisions(key, end []byte, atRev int64) []revision {
return rev
}
func (i *fakeIndex) CountRevisions(key, end []byte, atRev int64) int {
_, rev := i.Range(key, end, atRev)
return len(rev)
}
func (i *fakeIndex) Get(key []byte, atRev int64) (rev, created revision, ver int64, err error) {
i.Recorder.Record(testutil.Action{Name: "get", Params: []interface{}{key, atRev}})
r := <-i.indexGetRespc

9
mvcc/kvstore_txn.go
View File

@ -125,15 +125,16 @@ func (tr *storeTxnRead) rangeKeys(key, end []byte, curRev int64, ro RangeOptions
if rev < tr.s.compactMainRev {
return &RangeResult{KVs: nil, Count: -1, Rev: 0}, ErrCompacted
}
if ro.Count {
total := tr.s.kvindex.CountRevisions(key, end, rev)
tr.trace.Step("count revisions from in-memory index tree")
return &RangeResult{KVs: nil, Count: total, Rev: curRev}, nil
}
revpairs := tr.s.kvindex.Revisions(key, end, rev)
tr.trace.Step("range keys from in-memory index tree")
if len(revpairs) == 0 {
return &RangeResult{KVs: nil, Count: 0, Rev: curRev}, nil
}
if ro.Count {
return &RangeResult{KVs: nil, Count: len(revpairs), Rev: curRev}, nil
}
limit := int(ro.Limit)
if limit <= 0 || limit > len(revpairs) {