vault backup: 2026-04-22 10:10:19
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+62
-74
@@ -244,89 +244,77 @@ graph LR
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## 参考实现
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### 伪代码
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### 核心实现（伪代码）
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```python
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class HeavyKeeper:
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def __init__(self, m, L, threshold, decay_factor):
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self.m = m # 每层桶数
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self.L = L # 哈希层数
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self.threshold = threshold
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self.decay_factor = decay_factor # 衰减因子
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# 初始化多层 sketch
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self.buckets = [[KeeperBucket() for _ in range(m)]
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for _ in range(L)]
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# 初始化哈希函数
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self.hash_funcs = [get_hash_func(i) for i in range(L)]
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def insert(self, item, timestamp):
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def __init__(self, m, L, decay_factor):
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self.m, self.L = m, L
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self.decay_factor = decay_factor
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self.buckets = [[Bucket() for _ in range(m)] for _ in range(L)]
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def insert(self, item):
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for layer in range(self.L):
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idx = self.hash_funcs[layer](item) % self.m
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bucket = self.buckets[layer][idx]
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bucket = self.buckets[layer][hash(item) % self.m]
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if bucket.item == item:
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# 守护项匹配，直接计数（大象流强化）
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bucket.count += 1
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bucket.last_seen = timestamp
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bucket.count += 1 # 守护项匹配，直接计数
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else:
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# 计算替换概率
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estimated_freq = self._estimate_freq(item)
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replace_prob = min(1, estimated_freq / bucket.count)
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if random.random() < replace_prob:
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# 替换为新项（大象流夺权）
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bucket.item = item
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bucket.count = 1
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bucket.error = bucket.count
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bucket.last_seen = timestamp
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# 空桶直接占领；否则按概率争夺
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prob = 1 if bucket.count == 0 else min(1, self._estimate(item) / bucket.count)
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if random() < prob:
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bucket.item, bucket.count, bucket.error = item, 1, 0 # 替换为新项
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else:
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# 不替换，仅增加误差（老鼠流被阻拦）
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bucket.error += 1
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def apply_decay(self, current_time):
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"""应用衰减机制"""
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for layer in range(self.L):
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for bucket in self.buckets[layer]:
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elapsed = current_time - bucket.last_seen
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if elapsed > DECAY_INTERVAL:
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bucket.count *= self.decay_factor
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bucket.error *= self.decay_factor
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# 归零清理
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if bucket.count < 1:
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bucket.item = None
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bucket.count = 0
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bucket.error = 0
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def query(self, item):
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"""查询Item的频率估计"""
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min_count = float('inf')
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for layer in range(self.L):
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idx = self.hash_funcs[layer](item) % self.m
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bucket = self.buckets[layer][idx]
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if bucket.item == item:
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min_count = min(min_count, bucket.count)
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return min_count if min_count != float('inf') else 0
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def get_top_k(self, k):
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"""获取Top K大象流"""
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candidates = {}
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for layer in range(self.L):
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for bucket in self.buckets[layer]:
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if bucket.count >= self.threshold and bucket.item:
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item = bucket.item
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candidates[item] = max(candidates.get(item, 0),
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bucket.count)
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# 返回 Top-k
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return sorted(candidates.items(),
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key=lambda x: x[1],
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reverse=True)[:k]
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bucket.error += 1 # 不替换，仅增加误差
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```
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### Go 参考实现
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```go
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package heavykeeper
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type Bucket struct {
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Item []byte
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Count uint32
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Error uint32
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}
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type HeavyKeeper struct {
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m, L uint32
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decayFactor float64
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buckets [][]Bucket
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hashFuncs []func([]byte) uint64
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}
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func (hk *HeavyKeeper) Insert(item []byte) {
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for layer := uint32(0); layer < hk.L; layer++ {
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idx := hk.hashFuncs[layer](item) % hk.m
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bucket := &hk.buckets[layer][idx]
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if bytes.Equal(bucket.Item, item) {
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bucket.Count++
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continue
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}
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var prob float64
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if bucket.Count == 0 {
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prob = 1 // 空桶直接占领
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} else {
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prob = float64(hk.estimate(item)) / float64(bucket.Count)
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if prob > 1 {
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prob = 1
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}
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}
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if rand.Float64() < prob {
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bucket.Item, bucket.Count, bucket.Error = item, 1, 0
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} else {
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bucket.Error++
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}
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}
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}
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```
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> **说明**：`insert` 是核心逻辑——对每层哈希找桶，匹配守护项则计数，否则按概率争夺。伪代码省略了衰减、查询、Top-K 等辅助方法，实际部署时按需补充。
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## 相关算法对比
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| 算法 | 空间复杂度 | 大象流准确性 | 老鼠流过滤 | 衰减支持 | 适用场景 |
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@@ -0,0 +1,132 @@
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---
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tags: [CS, TOOLS, Docker, 容器化]
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create time: 2026-04-21
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---
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# Docker 安装指南
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## 概述
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Docker 是一个开源的应用容器引擎，让开发者可以打包他们的应用以及依赖包到一个可移植的容器中，然后发布到任何流行的 Linux 机器上，也可以实现虚拟化。容器是完全使用沙箱机制，相互之间不会有任何接口。
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## 系统要求
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- Ubuntu 24.04 LTS (Jammy Jellyfish)
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- 64-bit architecture
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- 内核版本 4.15 或更高版本
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## 安装步骤
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### 1. 更新系统包索引
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```bash
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sudo apt update
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```
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### 2. 安装必要的依赖包
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```bash
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sudo apt install apt-transport-https ca-certificates curl gnupg lsb-release
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```
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### 3. 添加 Docker 官方 GPG 密钥
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```bash
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curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
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```
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### 4. 添加 Docker APT 仓库
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```bash
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echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
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```
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### 5. 更新包索引
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```bash
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sudo apt update
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```
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### 6. 安装 Docker Engine
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```bash
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sudo apt install docker-ce docker-ce-cli containerd.io docker-compose-plugin
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```
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### 7. 启动并启用 Docker 服务
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```bash
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sudo systemctl start docker
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sudo systemctl enable docker
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```
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### 8. 将当前用户添加到 docker 组（可选，但推荐）
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```bash
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sudo usermod -aG docker $USER
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```
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> 请注意：执行此命令后，需要重新登录或运行 `newgrp docker` 命令使组成员身份生效。
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## 验证安装
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执行以下命令来验证 Docker 是否正确安装：
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```bash
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docker --version
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```
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运行一个简单的测试容器：
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```bash
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docker run hello-world
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```
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## 常用命令
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| 命令 | 说明 |
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|------|------|
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| `docker pull [镜像名]` | 拉取镜像 |
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| `docker run [镜像名]` | 运行容器 |
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| `docker ps` | 显示正在运行的容器 |
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| `docker ps -a` | 显示所有容器 |
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| `docker images` | 显示所有镜像 |
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| `docker stop [容器名/ID]` | 停止容器 |
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| `docker rm [容器名/ID]` | 删除容器 |
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| `docker rmi [镜像名/ID]` | 删除镜像 |
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## 后续操作
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- **Docker Compose**：如果您需要使用 Docker Compose，在安装 Docker 时已包含，可直接使用
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- **配置 Docker**：可以修改 `/etc/docker/daemon.json` 文件进行配置
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## 安全说明
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- 不要使用 root 用户运行 Docker
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- 为非 root 用户添加 docker 组时要小心，因为该用户将具有 root 权限
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- 定期更新 Docker 和容器镜像
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## 故障排除
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### 权限问题
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如果遇到权限问题，确保当前用户已被添加到 docker 组中：
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```bash
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sudo usermod -aG docker $USER
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```
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然后注销并重新登录。
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### 服务启动失败
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如果 Docker 服务无法启动，可以检查其状态：
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```bash
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sudo systemctl status docker
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```
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## 参考资料
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- [Docker 官方安装指南](https://docs.docker.com/engine/install/ubuntu/)
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- [Ubuntu 24.04 Docker 安装文档](https://ubuntu.com/server/docs/container-docker)
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