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util.go
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/
util.go
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// Copyright (c) 2016 Couchbase, Inc.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed under the
// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
package nitro
import (
"unsafe"
)
// partitionPivots returns pivot items which partitions items in the store
// into nsplits parititons.
func (m *Nitro) partitionPivots(snap *Snapshot, nsplits int) []*Item {
var pivotItems []*Item
tmpIter := m.NewIterator(snap)
if tmpIter == nil {
panic("iterator cannot be nil")
}
defer tmpIter.Close()
barrier := m.store.GetAccesBarrier()
token := barrier.Acquire()
defer barrier.Release(token)
pivotItems = append(pivotItems, nil) // start item
pivotPtrs := m.store.GetRangeSplitItems(nsplits)
for _, itmPtr := range pivotPtrs {
itm := m.ptrToItem(itmPtr)
tmpIter.Seek(itm.Bytes())
if tmpIter.Valid() {
prevItm := pivotItems[len(pivotItems)-1]
// Find bigger item than prev pivot
if prevItm == nil || m.insCmp(unsafe.Pointer(itm), unsafe.Pointer(prevItm)) > 0 {
pivotItems = append(pivotItems, itm)
}
}
}
pivotItems = append(pivotItems, nil) // end item
return pivotItems
}