github.com/yankunsam/loki/v2@v2.6.3-0.20220817130409-389df5235c27/pkg/storage/stores/tsdb/index/postingsstats.go (about)

     1  // Copyright 2019 The Prometheus Authors
     2  // Licensed under the Apache License, Version 2.0 (the "License");
     3  // you may not use this file except in compliance with the License.
     4  // You may obtain a copy of the License at
     5  //
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package index
    15  
    16  import (
    17  	"math"
    18  	"sort"
    19  )
    20  
    21  // Stat holds values for a single cardinality statistic.
    22  type Stat struct {
    23  	Name  string
    24  	Count uint64
    25  }
    26  
    27  type maxHeap struct {
    28  	maxLength int
    29  	minValue  uint64
    30  	minIndex  int
    31  	Items     []Stat
    32  }
    33  
    34  func (m *maxHeap) init(len int) {
    35  	m.maxLength = len
    36  	m.minValue = math.MaxUint64
    37  	m.Items = make([]Stat, 0, len)
    38  }
    39  
    40  func (m *maxHeap) push(item Stat) {
    41  	if len(m.Items) < m.maxLength {
    42  		if item.Count < m.minValue {
    43  			m.minValue = item.Count
    44  			m.minIndex = len(m.Items)
    45  		}
    46  		m.Items = append(m.Items, item)
    47  		return
    48  	}
    49  	if item.Count < m.minValue {
    50  		return
    51  	}
    52  
    53  	m.Items[m.minIndex] = item
    54  	m.minValue = item.Count
    55  
    56  	for i, stat := range m.Items {
    57  		if stat.Count < m.minValue {
    58  			m.minValue = stat.Count
    59  			m.minIndex = i
    60  		}
    61  	}
    62  }
    63  
    64  func (m *maxHeap) get() []Stat {
    65  	sort.Slice(m.Items, func(i, j int) bool {
    66  		return m.Items[i].Count > m.Items[j].Count
    67  	})
    68  	return m.Items
    69  }