74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
// Copyright 2015 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package segmentmap
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import (
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"hash/crc32"
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"github.com/juju/errors"
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)
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// SegmentMap is used for handle a big map slice by slice
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type SegmentMap struct {
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size int
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maps []map[string]interface{}
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}
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// NewSegmentMap crate a new SegmentMap
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func NewSegmentMap(size int) *SegmentMap {
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sm := &SegmentMap{
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maps: make([]map[string]interface{}, size),
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size: size,
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}
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for i := 0; i < size; i++ {
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sm.maps[i] = make(map[string]interface{})
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}
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return sm
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}
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// Get is the same as map[k]
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func (sm *SegmentMap) Get(key []byte) (interface{}, bool) {
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idx := int(crc32.ChecksumIEEE(key)) % sm.size
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val, ok := sm.maps[idx][string(key)]
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return val, ok
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}
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// GetSegment gets the map specific by index
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func (sm *SegmentMap) GetSegment(index int) (map[string]interface{}, error) {
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if index >= len(sm.maps) {
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return nil, errors.Errorf("index out of bound")
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}
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return sm.maps[index], nil
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}
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// Set if empty, return whether already exists
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func (sm *SegmentMap) Set(key []byte, value interface{}, force bool) (exist bool) {
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idx := int(crc32.ChecksumIEEE(key)) % sm.size
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k := string(key)
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_, exist = sm.maps[idx][k]
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if exist && !force {
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return exist
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}
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sm.maps[idx][k] = value
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return exist
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}
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// SegmentCount return how many inner segments
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func (sm *SegmentMap) SegmentCount() int {
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return sm.size
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}
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