Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
77 lines (65 sloc) 2.06 KB
// Copyright (c) 2014 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 upsidedown
import (
"encoding/binary"
)
var mergeOperator upsideDownMerge
var dictionaryTermIncr []byte
var dictionaryTermDecr []byte
func init() {
dictionaryTermIncr = make([]byte, 8)
binary.LittleEndian.PutUint64(dictionaryTermIncr, uint64(1))
dictionaryTermDecr = make([]byte, 8)
var negOne = int64(-1)
binary.LittleEndian.PutUint64(dictionaryTermDecr, uint64(negOne))
}
type upsideDownMerge struct{}
func (m *upsideDownMerge) FullMerge(key, existingValue []byte, operands [][]byte) ([]byte, bool) {
// set up record based on key
dr, err := NewDictionaryRowK(key)
if err != nil {
return nil, false
}
if len(existingValue) > 0 {
// if existing value, parse it
err = dr.parseDictionaryV(existingValue)
if err != nil {
return nil, false
}
}
// now process operands
for _, operand := range operands {
next := int64(binary.LittleEndian.Uint64(operand))
if next < 0 && uint64(-next) > dr.count {
// subtracting next from existing would overflow
dr.count = 0
} else if next < 0 {
dr.count -= uint64(-next)
} else {
dr.count += uint64(next)
}
}
return dr.Value(), true
}
func (m *upsideDownMerge) PartialMerge(key, leftOperand, rightOperand []byte) ([]byte, bool) {
left := int64(binary.LittleEndian.Uint64(leftOperand))
right := int64(binary.LittleEndian.Uint64(rightOperand))
rv := make([]byte, 8)
binary.LittleEndian.PutUint64(rv, uint64(left+right))
return rv, true
}
func (m *upsideDownMerge) Name() string {
return "upsideDownMerge"
}
You can’t perform that action at this time.