修复热点数据从文件系统转移到内存时可能不完整的Bug/实现部分Partial Content功能

2025-11-28 02:50:25 +08:00 · 2022-02-21 17:33:58 +08:00
parent 35e8b1a9ba
commit a6a44bf4d4
16 changed files with 704 additions and 87 deletions
--- a/internal/caches/partial_ranges.go
+++ b/internal/caches/partial_ranges.go
@@ -0,0 +1,143 @@
+// Copyright 2022 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package caches
+
+import (
+	"encoding/json"
+)
+
+// PartialRanges 内容分区范围定义
+type PartialRanges struct {
+	ranges [][2]int64
+}
+
+// NewPartialRanges 获取新对象
+func NewPartialRanges() *PartialRanges {
+	return &PartialRanges{ranges: [][2]int64{}}
+}
+
+// NewPartialRangesFromJSON 从JSON中解析范围
+func NewPartialRangesFromJSON(data []byte) (*PartialRanges, error) {
+	var rs = [][2]int64{}
+	err := json.Unmarshal(data, &rs)
+	if err != nil {
+		return nil, err
+	}
+	var r = NewPartialRanges()
+	r.ranges = rs
+	return r, nil
+}
+
+// Add 添加新范围
+func (this *PartialRanges) Add(begin int64, end int64) {
+	if begin > end {
+		begin, end = end, begin
+	}
+
+	var nr = [2]int64{begin, end}
+
+	var count = len(this.ranges)
+	if count == 0 {
+		this.ranges = [][2]int64{nr}
+		return
+	}
+
+	// insert
+	// TODO 将来使用二分法改进
+	var index = -1
+	for i, r := range this.ranges {
+		if r[0] > begin || (r[0] == begin && r[1] >= end) {
+			index = i
+			this.ranges = append(this.ranges, [2]int64{})
+			copy(this.ranges[index+1:], this.ranges[index:])
+			this.ranges[index] = nr
+			break
+		}
+	}
+
+	if index == -1 {
+		index = count
+		this.ranges = append(this.ranges, nr)
+	}
+
+	this.merge(index)
+}
+
+// Ranges 获取所有范围
+func (this *PartialRanges) Ranges() [][2]int64 {
+	return this.ranges
+}
+
+// Contains 检查是否包含某个范围
+func (this *PartialRanges) Contains(begin int64, end int64) bool {
+	if len(this.ranges) == 0 {
+		return true
+	}
+
+	// TODO 使用二分法查找改进性能
+	for _, r2 := range this.ranges {
+		if r2[0] <= begin && r2[1] >= end {
+			return true
+		}
+	}
+
+	return false
+}
+
+// AsJSON 转换为JSON
+func (this *PartialRanges) AsJSON() ([]byte, error) {
+	return json.Marshal(this.ranges)
+}
+
+func (this *PartialRanges) merge(index int) {
+	// forward
+	var lastIndex = index
+	for i := index; i >= 1; i-- {
+		var curr = this.ranges[i]
+		var prev = this.ranges[i-1]
+		var w1 = this.w(curr)
+		var w2 = this.w(prev)
+		if w1+w2 >= this.max(curr[1], prev[1])-this.min(curr[0], prev[0])-1 {
+			prev = [2]int64{this.min(curr[0], prev[0]), this.max(curr[1], prev[1])}
+			this.ranges[i-1] = prev
+			this.ranges = append(this.ranges[:i], this.ranges[i+1:]...)
+			lastIndex = i - 1
+		} else {
+			break
+		}
+	}
+
+	// backward
+	index = lastIndex
+	for index < len(this.ranges)-1 {
+		var curr = this.ranges[index]
+		var next = this.ranges[index+1]
+		var w1 = this.w(curr)
+		var w2 = this.w(next)
+		if w1+w2 >= this.max(curr[1], next[1])-this.min(curr[0], next[0])-1 {
+			curr = [2]int64{this.min(curr[0], next[0]), this.max(curr[1], next[1])}
+			this.ranges = append(this.ranges[:index], this.ranges[index+1:]...)
+			this.ranges[index] = curr
+		} else {
+			break
+		}
+	}
+}
+
+func (this *PartialRanges) w(r [2]int64) int64 {
+	return r[1] - r[0]
+}
+
+func (this *PartialRanges) min(n1 int64, n2 int64) int64 {
+	if n1 <= n2 {
+		return n1
+	}
+	return n2
+}
+
+func (this *PartialRanges) max(n1 int64, n2 int64) int64 {
+	if n1 >= n2 {
+		return n1
+	}
+	return n2
+}