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Merge pull request #9296 from xiang90/c_r
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mvcc: allow large concurrent reads under light  write workload
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xiang90 authored Feb 9, 2018
2 parents 54b21fa + 3ebee21 commit 0a20767
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Showing 2 changed files with 11 additions and 6 deletions.
10 changes: 4 additions & 6 deletions internal/mvcc/backend/backend.go
Original file line number Diff line number Diff line change
Expand Up @@ -271,7 +271,9 @@ func (b *backend) run() {
b.batchTx.CommitAndStop()
return
}
b.batchTx.Commit()
if b.batchTx.safePending() != 0 {
b.batchTx.Commit()
}
t.Reset(b.batchInterval)
}
}
Expand Down Expand Up @@ -302,11 +304,7 @@ func (b *backend) defrag() error {
b.mu.Lock()
defer b.mu.Unlock()

// block concurrent read requests while resetting tx
b.readTx.mu.Lock()
defer b.readTx.mu.Unlock()

b.batchTx.unsafeCommit(true)
b.batchTx.commit(true)
b.batchTx.tx = nil

tmpdb, err := bolt.Open(b.db.Path()+".tmp", 0600, boltOpenOptions)
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7 changes: 7 additions & 0 deletions internal/mvcc/backend/batch_tx.go
Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,7 @@ func unsafeRange(c *bolt.Cursor, key, endKey []byte, limit int64) (keys [][]byte
isMatch = func(b []byte) bool { return bytes.Equal(b, key) }
limit = 1
}

for ck, cv := c.Seek(key); ck != nil && isMatch(ck); ck, cv = c.Next() {
vs = append(vs, cv)
keys = append(keys, ck)
Expand Down Expand Up @@ -154,6 +155,12 @@ func (t *batchTx) Unlock() {
t.Mutex.Unlock()
}

func (t *batchTx) safePending() int {
t.Mutex.Lock()
defer t.Mutex.Unlock()
return t.pending
}

func (t *batchTx) commit(stop bool) {
// commit the last tx
if t.tx != nil {
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