110 lines
1.7 KiB
Go
110 lines
1.7 KiB
Go
package reads
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import (
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"bytes"
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"strings"
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"github.com/influxdata/influxdb/models"
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)
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// tagsKeyMerger is responsible for determining a merged set of tag keys
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type KeyMerger struct {
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i int
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tmp [][]byte
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keys [2][][]byte
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}
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func (km *KeyMerger) Clear() {
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km.i = 0
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km.keys[0] = km.keys[0][:0]
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if km.tmp != nil {
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tmp := km.tmp[:cap(km.tmp)]
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for i := range tmp {
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tmp[i] = nil
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}
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}
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}
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func (km *KeyMerger) Get() [][]byte { return km.keys[km.i&1] }
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func (km *KeyMerger) String() string {
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var s []string
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for _, k := range km.Get() {
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s = append(s, string(k))
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}
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return strings.Join(s, ",")
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}
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func (km *KeyMerger) MergeTagKeys(tags models.Tags) {
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if cap(km.tmp) < len(tags) {
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km.tmp = make([][]byte, len(tags))
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} else {
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km.tmp = km.tmp[:len(tags)]
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}
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for i := range tags {
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km.tmp[i] = tags[i].Key
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}
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km.MergeKeys(km.tmp)
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}
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func (km *KeyMerger) MergeKeys(in [][]byte) {
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keys := km.keys[km.i&1]
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i, j := 0, 0
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for i < len(keys) && j < len(in) && bytes.Equal(keys[i], in[j]) {
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i++
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j++
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}
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if j == len(in) {
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// no new tags
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return
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}
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km.i = (km.i + 1) & 1
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l := len(keys) + len(in)
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if cap(km.keys[km.i]) < l {
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km.keys[km.i] = make([][]byte, l)
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} else {
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km.keys[km.i] = km.keys[km.i][:l]
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}
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keya := km.keys[km.i]
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// back up the pointers
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if i > 0 {
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i--
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j--
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}
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k := i
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copy(keya[:k], keys[:k])
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for i < len(keys) && j < len(in) {
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cmp := bytes.Compare(keys[i], in[j])
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if cmp < 0 {
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keya[k] = keys[i]
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i++
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} else if cmp > 0 {
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keya[k] = in[j]
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j++
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} else {
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keya[k] = keys[i]
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i++
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j++
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}
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k++
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}
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if i < len(keys) {
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k += copy(keya[k:], keys[i:])
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}
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if j < len(in) {
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k += copy(keya[k:], in[j:])
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}
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km.keys[km.i] = keya[:k]
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}
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