a9c07acbfa
refactor to share code in emulated batch refactor to share code in emulated merge refactor index kvstore benchmarks to share more code refactor index kvstore benchmarks to be more repeatable
121 lines
3.4 KiB
Go
121 lines
3.4 KiB
Go
// Copyright (c) 2014 Couchbase, Inc.
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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// except in compliance with the License. You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed under the
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// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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// either express or implied. See the License for the specific language governing permissions
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// and limitations under the License.
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package store
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import (
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"fmt"
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)
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// At the moment this happens to be the same interface as described by
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// RocksDB, but this may not always be the case.
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type MergeOperator interface {
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// FullMerge the full sequence of operands on top of the existingValue
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// if no value currently exists, existingValue is nil
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// return the merged value, and success/failure
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FullMerge(key, existingValue []byte, operands [][]byte) ([]byte, bool)
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// Partially merge these two operands.
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// If partial merge cannot be done, return nil,false, which will defer
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// all processing until the FullMerge is done.
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PartialMerge(key, leftOperand, rightOperand []byte) ([]byte, bool)
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// Name returns an identifier for the operator
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Name() string
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}
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// EmulatedMergeSingle removes some duplicated code across
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// KV stores which do not support merge operations
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// on their own. It is up to the caller to ensure
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// that an appropriate lock has been acquired in
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// order for this behavior to be valid
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func EmulatedMergeSingle(writer KVWriter, mo MergeOperator, key []byte, operand []byte) error {
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existingValue, err := writer.Get(key)
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if err != nil {
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return err
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}
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newValue, ok := mo.FullMerge(key, existingValue, [][]byte{operand})
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if !ok {
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return fmt.Errorf("merge operator returned failure")
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}
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err = writer.Set(key, newValue)
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if err != nil {
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return err
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}
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return nil
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}
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type EmulatedMerge struct {
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merges map[string][][]byte
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mo MergeOperator
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}
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func NewEmulatedMerge(mo MergeOperator) *EmulatedMerge {
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return &EmulatedMerge{
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merges: make(map[string][][]byte),
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mo: mo,
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}
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}
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func (m *EmulatedMerge) Merge(key, val []byte) {
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ops, ok := m.merges[string(key)]
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if ok && len(ops) > 0 {
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last := ops[len(ops)-1]
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mergedVal, partialMergeOk := m.mo.PartialMerge(key, last, val)
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if partialMergeOk {
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// replace last entry with the result of the merge
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ops[len(ops)-1] = mergedVal
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} else {
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// could not partial merge, append this to the end
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ops = append(ops, val)
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}
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} else {
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ops = [][]byte{val}
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}
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m.merges[string(key)] = ops
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}
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func (m *EmulatedMerge) Execute(w KVWriter) error {
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for k, mergeOps := range m.merges {
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kb := []byte(k)
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existingVal, err := w.Get(kb)
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if err != nil {
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return err
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}
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mergedVal, fullMergeOk := m.mo.FullMerge(kb, existingVal, mergeOps)
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if !fullMergeOk {
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return fmt.Errorf("merge operator returned failure")
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}
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err = w.Set(kb, mergedVal)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func (m *EmulatedMerge) ExecuteDeferred(w KVWriter) ([]*op, error) {
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rv := make([]*op, 0, 1000)
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for k, mergeOps := range m.merges {
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kb := []byte(k)
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existingVal, err := w.Get(kb)
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if err != nil {
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return nil, err
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}
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mergedVal, fullMergeOk := m.mo.FullMerge(kb, existingVal, mergeOps)
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if !fullMergeOk {
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return nil, fmt.Errorf("merge operator returned failure")
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}
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rv = append(rv, &op{kb, mergedVal})
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}
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return rv, nil
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}
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