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7d7b9eacff
On a 32 bit architecture the size of int is 32 bits. Thus converting from
int64, uint64 can overflow it and flip the sign.
Try for yourself in playground:
package main
import "fmt"
func main() {
x := int64(0x1F0000001)
y := int64(1)
z := int32(x - y) // numerically this is 0x1F0000000
fmt.Printf("%v\n", z)
}
Prints -268435456 as if x was smaller.
Followup to #12650
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
78 lines
1.6 KiB
Go
78 lines
1.6 KiB
Go
// Copyright 2019 The Prometheus Authors
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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 index
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import (
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"math"
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"golang.org/x/exp/slices"
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)
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// Stat holds values for a single cardinality statistic.
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type Stat struct {
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Name string
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Count uint64
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}
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type maxHeap struct {
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maxLength int
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minValue uint64
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minIndex int
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Items []Stat
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}
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func (m *maxHeap) init(length int) {
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m.maxLength = length
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m.minValue = math.MaxUint64
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m.Items = make([]Stat, 0, length)
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}
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func (m *maxHeap) push(item Stat) {
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if len(m.Items) < m.maxLength {
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if item.Count < m.minValue {
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m.minValue = item.Count
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m.minIndex = len(m.Items)
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}
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m.Items = append(m.Items, item)
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return
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}
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if item.Count < m.minValue {
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return
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}
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m.Items[m.minIndex] = item
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m.minValue = item.Count
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for i, stat := range m.Items {
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if stat.Count < m.minValue {
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m.minValue = stat.Count
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m.minIndex = i
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}
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}
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}
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func (m *maxHeap) get() []Stat {
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slices.SortFunc(m.Items, func(a, b Stat) int {
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switch {
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case b.Count < a.Count:
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return -1
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case b.Count > a.Count:
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return 1
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default:
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return 0
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}
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})
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return m.Items
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}
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