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mvcc: cache consistentIndex

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Called on every entry apply and boltdb requests aren't free.
This commit is contained in:
Anthony Romano 2017-05-02 17:18:10 -07:00
parent 343a018361
commit 73dee0bec4
1 changed files with 15 additions and 3 deletions
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18
mvcc/kvstore.go
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@ -19,6 +19,7 @@ import (
"errors"
"math"
"sync"
"sync/atomic"
"time"
"github.com/coreos/etcd/lease"
@ -67,6 +68,10 @@ type store struct {
ReadView
WriteView
// consistentIndex caches the "consistent_index" key's value. Accessed
// through atomics so must be 64-bit aligned.
consistentIndex uint64
// mu read locks for txns and write locks for non-txn store changes.
mu sync.RWMutex
@ -234,6 +239,7 @@ func (s *store) Restore(b backend.Backend) error {
close(s.stopc)
s.fifoSched.Stop()
atomic.StoreUint64(&s.consistentIndex, 0)
s.b = b
s.kvindex = newTreeIndex()
s.currentRev = 1
@ -380,14 +386,18 @@ func (s *store) saveIndex(tx backend.BatchTx) {
return
}
bs := s.bytesBuf8
binary.BigEndian.PutUint64(bs, s.ig.ConsistentIndex())
ci := s.ig.ConsistentIndex()
binary.BigEndian.PutUint64(bs, ci)
// put the index into the underlying backend
// tx has been locked in TxnBegin, so there is no need to lock it again
tx.UnsafePut(metaBucketName, consistentIndexKeyName, bs)
atomic.StoreUint64(&s.consistentIndex, ci)
}
func (s *store) ConsistentIndex() uint64 {
// TODO: cache index in a uint64 field?
if ci := atomic.LoadUint64(&s.consistentIndex); ci > 0 {
return ci
}
tx := s.b.BatchTx()
tx.Lock()
defer tx.Unlock()
@ -395,7 +405,9 @@ func (s *store) ConsistentIndex() uint64 {
if len(vs) == 0 {
return 0
}
return binary.BigEndian.Uint64(vs[0])
v := binary.BigEndian.Uint64(vs[0])
atomic.StoreUint64(&s.consistentIndex, v)
return v
}
// appendMarkTombstone appends tombstone mark to normal revision bytes.