forked from gitea/gitea
144 lines
3.4 KiB
Go
144 lines
3.4 KiB
Go
// Copyright The OpenTelemetry Authors
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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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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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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 label // import "go.opentelemetry.io/otel/label"
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// Iterator allows iterating over the set of labels in order,
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// sorted by key.
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type Iterator struct {
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storage *Set
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idx int
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}
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// MergeIterator supports iterating over two sets of labels while
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// eliminating duplicate values from the combined set. The first
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// iterator value takes precedence.
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type MergeIterator struct {
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one oneIterator
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two oneIterator
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current KeyValue
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}
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type oneIterator struct {
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iter Iterator
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done bool
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label KeyValue
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}
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// Next moves the iterator to the next position. Returns false if there
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// are no more labels.
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func (i *Iterator) Next() bool {
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i.idx++
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return i.idx < i.Len()
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}
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// Label returns current KeyValue. Must be called only after Next returns
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// true.
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func (i *Iterator) Label() KeyValue {
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kv, _ := i.storage.Get(i.idx)
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return kv
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}
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// Attribute is a synonym for Label().
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func (i *Iterator) Attribute() KeyValue {
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return i.Label()
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}
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// IndexedLabel returns current index and label. Must be called only
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// after Next returns true.
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func (i *Iterator) IndexedLabel() (int, KeyValue) {
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return i.idx, i.Label()
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}
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// Len returns a number of labels in the iterator's `*Set`.
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func (i *Iterator) Len() int {
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return i.storage.Len()
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}
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// ToSlice is a convenience function that creates a slice of labels
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// from the passed iterator. The iterator is set up to start from the
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// beginning before creating the slice.
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func (i *Iterator) ToSlice() []KeyValue {
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l := i.Len()
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if l == 0 {
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return nil
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}
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i.idx = -1
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slice := make([]KeyValue, 0, l)
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for i.Next() {
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slice = append(slice, i.Label())
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}
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return slice
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}
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// NewMergeIterator returns a MergeIterator for merging two label sets
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// Duplicates are resolved by taking the value from the first set.
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func NewMergeIterator(s1, s2 *Set) MergeIterator {
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mi := MergeIterator{
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one: makeOne(s1.Iter()),
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two: makeOne(s2.Iter()),
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}
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return mi
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}
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func makeOne(iter Iterator) oneIterator {
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oi := oneIterator{
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iter: iter,
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}
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oi.advance()
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return oi
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}
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func (oi *oneIterator) advance() {
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if oi.done = !oi.iter.Next(); !oi.done {
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oi.label = oi.iter.Label()
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}
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}
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// Next returns true if there is another label available.
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func (m *MergeIterator) Next() bool {
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if m.one.done && m.two.done {
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return false
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}
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if m.one.done {
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m.current = m.two.label
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m.two.advance()
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return true
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}
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if m.two.done {
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m.current = m.one.label
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m.one.advance()
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return true
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}
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if m.one.label.Key == m.two.label.Key {
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m.current = m.one.label // first iterator label value wins
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m.one.advance()
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m.two.advance()
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return true
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}
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if m.one.label.Key < m.two.label.Key {
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m.current = m.one.label
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m.one.advance()
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return true
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}
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m.current = m.two.label
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m.two.advance()
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return true
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}
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// Label returns the current value after Next() returns true.
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func (m *MergeIterator) Label() KeyValue {
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return m.current
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}
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