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test-repo/docs/.vitepress/theme/components/appendix/queue-design/PeakShavingDemo.vue
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<!--
PeakShavingDemo.vue
削峰填谷演示 - 流量缓冲可视化
-->
<template>
<div class="peak-shaving-demo">
<div class="header">
<div class="title">削峰填谷把高峰"摊平"</div>
<div class="subtitle">模拟流量突增场景观察队列如何保护后端系统</div>
</div>
<div class="main-layout">
<!-- 左侧控制面板 -->
<div class="controls-panel">
<div class="control-group">
<div class="label-row">
<span class="label">处理能力 (Consumer)</span>
<span class="value">{{ processRate }} req/s</span>
</div>
<input
v-model="processRate"
type="range"
min="50"
max="1000"
step="50"
class="range-input process-range"
/>
<div class="desc">后端系统的最大处理速度</div>
</div>
<div class="control-group">
<div class="label-row">
<span class="label">队列容量 (Queue Size)</span>
<span class="value">{{ queueCapacity }}</span>
</div>
<input
v-model="queueCapacity"
type="range"
min="500"
max="10000"
step="500"
class="range-input queue-range"
/>
<div class="desc">消息队列能暂存的最大请求数</div>
</div>
<div class="actions">
<button
class="action-btn burst-btn"
@click="triggerBurst"
:disabled="isBursting"
>
模拟秒杀流量突增
</button>
<button class="action-btn reset-btn" @click="reset">
🔄 重置系统
</button>
</div>
</div>
<!-- 右侧实时监控 -->
<div class="monitor-panel">
<!-- 状态指标卡片 -->
<div class="metrics-grid">
<div class="metric-item">
<div class="m-label">当前入站流量</div>
<div class="m-value blue">{{ currentRequestRate }} <span class="unit">req/s</span></div>
</div>
<div class="metric-item">
<div class="m-label">队列积压量</div>
<div class="m-value orange">{{ queueLength }} <span class="unit">msgs</span></div>
<div class="m-bar-bg">
<div class="m-bar-fill" :style="{ width: queuePercent + '%', background: queueColor }"></div>
</div>
</div>
<div class="metric-item">
<div class="m-label">实际处理速率</div>
<div class="m-value green">{{ currentProcessRate }} <span class="unit">req/s</span></div>
</div>
<div class="metric-item">
<div class="m-label">丢弃请求 (限流)</div>
<div class="m-value red">{{ rejectedCount }} <span class="unit">req</span></div>
</div>
</div>
<!-- 实时图表 -->
<div class="chart-container">
<canvas ref="chartCanvas" width="600" height="200"></canvas>
<div class="chart-legend">
<span class="legend-item"><span class="dot blue"></span>入站流量 (用户请求)</span>
<span class="legend-item"><span class="dot green"></span>处理流量 (系统负载)</span>
<span class="legend-item"><span class="dot orange"></span>队列积压</span>
</div>
</div>
</div>
</div>
<div class="scenario-tips">
<div class="tip-icon">💡</div>
<div class="tip-content">
<strong>核心原理</strong>
<strong>入站流量</strong>蓝色超过<strong>处理能力</strong>绿色直线多余的请求会被存入<strong>消息队列</strong>橙色区域
<br/>
一旦流量高峰过去系统会继续全速处理队列中的积压直到队列清空这就是"削峰填谷"
</div>
</div>
</div>
</template>
<script setup>
import { ref, computed, onMounted, onUnmounted } from 'vue'
// 核心状态
const processRate = ref(200) // 消费速率 (req/s)
const queueCapacity = ref(2000) // 队列容量
const queueLength = ref(0) // 当前队列长度
const rejectedCount = ref(0) // 总丢弃数
// 实时状态(用于展示和图表)
const currentRequestRate = ref(100) // 当前产生的请求速率
const currentProcessRate = ref(0) // 当前实际处理的速率
const isBursting = ref(false)
// 图表相关
const chartCanvas = ref(null)
let ctx = null
let animationFrameId = null
const historyLength = 300 // 记录最近 N 帧
const dataHistory = [] // { input, process, queue }
// 模拟循环
let lastTime = Date.now()
const updateLoop = () => {
const now = Date.now()
const dt = (now - lastTime) / 1000 // delta time in seconds
lastTime = now
// 1. 生成流量 (模拟波动的入站流量)
// 如果在突发模式下,流量激增;否则维持在低水位波动
let targetInput = isBursting.value ? 2000 : 100 + Math.random() * 50
// 平滑过渡入站流量
const smoothing = 0.1
currentRequestRate.value = Math.round(
currentRequestRate.value * (1 - smoothing) + targetInput * smoothing
)
// 2. 计算本帧新增请求
const newRequests = Math.round(currentRequestRate.value * dt * 10) // 放大系数以便观察
// 3. 入队逻辑
const availableSpace = queueCapacity.value - queueLength.value
const accepted = Math.min(newRequests, availableSpace)
const rejected = newRequests - accepted
queueLength.value += accepted
rejectedCount.value += rejected
// 4. 处理逻辑 (出队)
// 实际处理速率取决于:队列里有多少货,以及处理能力上限
// 如果队列足够多,就满负荷处理;否则只处理队列里有的
const maxProcessable = Math.round(processRate.value * dt * 10)
const processed = Math.min(queueLength.value, maxProcessable)
queueLength.value -= processed
// 计算瞬时处理速率 (用于显示)
currentProcessRate.value = Math.round(processed / (dt * 10))
// 5. 记录历史数据用于绘图
dataHistory.push({
input: currentRequestRate.value,
process: currentProcessRate.value,
queue: queueLength.value,
maxQueue: queueCapacity.value
})
if (dataHistory.length > historyLength) {
dataHistory.shift()
}
drawChart()
animationFrameId = requestAnimationFrame(updateLoop)
}
// 绘图逻辑
const drawChart = () => {
if (!ctx || !chartCanvas.value) return
// 动态调整画布大小以匹配显示尺寸(解决模糊和拉伸问题)
const canvas = chartCanvas.value
const dpr = window.devicePixelRatio || 1
const rect = canvas.getBoundingClientRect()
// 只有当尺寸变化时才重置 canvas 尺寸
if (canvas.width !== rect.width * dpr || canvas.height !== rect.height * dpr) {
canvas.width = rect.width * dpr
canvas.height = rect.height * dpr
// 缩放上下文以适配 DPR
ctx.scale(dpr, dpr)
}
// 逻辑宽高(CSS像素)
const width = rect.width
const height = rect.height
// 必须清除整个物理画布区域
ctx.clearRect(0, 0, width, height) // 由于 scale 了,这里用逻辑宽高即可吗?
// 不,clearRect 受 scale 影响。所以 clearRect(0,0, width, height) 是对的。
// 但是为了安全,通常建议用 save/restore 或者直接重置 transform 清除。
// 简单起见,我们假设 ctx.scale 已经生效。
// 实际上,最好是在 resize 时只设置一次 scale。
// 让我们简化一下:每帧都重置 transform 并清除
ctx.setTransform(1, 0, 0, 1, 0, 0)
ctx.clearRect(0, 0, canvas.width, canvas.height)
ctx.scale(dpr, dpr)
// 绘制网格背景
ctx.strokeStyle = '#eee'
ctx.lineWidth = 1
ctx.beginPath()
for (let i = 0; i < 5; i++) {
const y = height - (height / 4) * i
ctx.moveTo(0, y)
ctx.lineTo(width, y)
}
ctx.stroke()
if (dataHistory.length < 2) return
// 找出最大值用于Y轴缩放
const maxVal = Math.max(
2000, // 固定最小刻度
...dataHistory.map(d => Math.max(d.input, d.queue))
)
const yScale = (val) => height - (val / maxVal) * height * 0.9 // 留点余量
const xScale = (index) => (index / (historyLength - 1)) * width
// 1. 绘制队列积压 (填充区域)
ctx.fillStyle = 'rgba(249, 115, 22, 0.2)' // Orange transparent
ctx.beginPath()
ctx.moveTo(0, height)
dataHistory.forEach((d, i) => {
ctx.lineTo(xScale(i), yScale(d.queue))
})
ctx.lineTo(width, height)
ctx.fill()
// 队列线
ctx.strokeStyle = '#f97316' // Orange
ctx.lineWidth = 2
ctx.beginPath()
dataHistory.forEach((d, i) => {
if (i === 0) ctx.moveTo(xScale(i), yScale(d.queue))
else ctx.lineTo(xScale(i), yScale(d.queue))
})
ctx.stroke()
// 2. 绘制入站流量 (蓝色线)
ctx.strokeStyle = '#3b82f6' // Blue
ctx.lineWidth = 2
ctx.beginPath()
dataHistory.forEach((d, i) => {
if (i === 0) ctx.moveTo(xScale(i), yScale(d.input))
else ctx.lineTo(xScale(i), yScale(d.input))
})
ctx.stroke()
// 3. 绘制处理流量 (绿色线)
ctx.strokeStyle = '#22c55e' // Green
ctx.lineWidth = 2
ctx.beginPath()
dataHistory.forEach((d, i) => {
if (i === 0) ctx.moveTo(xScale(i), yScale(d.process))
else ctx.lineTo(xScale(i), yScale(d.process))
})
ctx.stroke()
}
// 模拟突发流量
const triggerBurst = () => {
if (isBursting.value) return
isBursting.value = true
// 3秒后恢复
setTimeout(() => {
isBursting.value = false
}, 3000)
}
const reset = () => {
queueLength.value = 0
rejectedCount.value = 0
dataHistory.length = 0
currentRequestRate.value = 100
isBursting.value = false
}
const queuePercent = computed(() => {
return Math.min(100, (queueLength.value / queueCapacity.value) * 100)
})
const queueColor = computed(() => {
if (queuePercent.value > 80) return '#ef4444'
if (queuePercent.value > 50) return '#f97316'
return '#22c55e'
})
onMounted(() => {
if (chartCanvas.value) {
ctx = chartCanvas.value.getContext('2d')
// 解决高清屏模糊
const dpr = window.devicePixelRatio || 1
const rect = chartCanvas.value.getBoundingClientRect()
// 简单处理:这里由于是固定width/height属性,暂时不处理resize
}
lastTime = Date.now()
animationFrameId = requestAnimationFrame(updateLoop)
})
onUnmounted(() => {
if (animationFrameId) {
cancelAnimationFrame(animationFrameId)
}
})
</script>
<style scoped>
.peak-shaving-demo {
border: 1px solid var(--vp-c-divider);
background: var(--vp-c-bg-soft);
border-radius: 12px;
padding: 20px;
margin: 20px 0;
font-family: var(--vp-font-family-base);
}
.header {
margin-bottom: 24px;
}
.title {
font-size: 18px;
font-weight: 600;
color: var(--vp-c-text-1);
}
.subtitle {
font-size: 14px;
color: var(--vp-c-text-2);
margin-top: 4px;
}
.main-layout {
display: grid;
grid-template-columns: 300px 1fr;
gap: 24px;
}
@media (max-width: 768px) {
.main-layout {
grid-template-columns: 1fr;
}
}
.controls-panel {
background: var(--vp-c-bg);
padding: 16px;
border-radius: 8px;
border: 1px solid var(--vp-c-divider);
display: flex;
flex-direction: column;
gap: 20px;
}
.control-group {
display: flex;
flex-direction: column;
gap: 8px;
}
.label-row {
display: flex;
justify-content: space-between;
align-items: center;
}
.label {
font-size: 14px;
font-weight: 500;
}
.value {
font-size: 13px;
font-family: monospace;
background: var(--vp-c-bg-alt);
padding: 2px 6px;
border-radius: 4px;
}
.desc {
font-size: 12px;
color: var(--vp-c-text-3);
}
.range-input {
width: 100%;
accent-color: var(--vp-c-brand);
}
.actions {
margin-top: auto;
display: flex;
flex-direction: column;
gap: 12px;
}
.action-btn {
padding: 10px;
border-radius: 6px;
border: none;
font-weight: 600;
cursor: pointer;
transition: all 0.2s;
}
.burst-btn {
background: var(--vp-c-brand);
color: white;
}
.burst-btn:hover:not(:disabled) {
background: var(--vp-c-brand-dark);
}
.burst-btn:disabled {
opacity: 0.5;
cursor: not-allowed;
}
.reset-btn {
background: var(--vp-c-bg-alt);
color: var(--vp-c-text-1);
border: 1px solid var(--vp-c-divider);
}
.reset-btn:hover {
background: var(--vp-c-bg-mute);
}
.monitor-panel {
display: flex;
flex-direction: column;
gap: 16px;
}
.metrics-grid {
display: grid;
grid-template-columns: repeat(2, 1fr);
gap: 12px;
}
.metric-item {
background: var(--vp-c-bg);
padding: 12px;
border-radius: 8px;
border: 1px solid var(--vp-c-divider);
}
.m-label {
font-size: 12px;
color: var(--vp-c-text-2);
margin-bottom: 4px;
}
.m-value {
font-size: 18px;
font-weight: 700;
display: flex;
align-items: baseline;
gap: 4px;
}
.unit {
font-size: 12px;
font-weight: 400;
opacity: 0.7;
}
.m-value.blue { color: #3b82f6; }
.m-value.green { color: #22c55e; }
.m-value.orange { color: #f97316; }
.m-value.red { color: #ef4444; }
.m-bar-bg {
height: 4px;
background: var(--vp-c-bg-soft);
border-radius: 2px;
margin-top: 8px;
overflow: hidden;
}
.m-bar-fill {
height: 100%;
transition: width 0.2s;
}
.chart-container {
flex: 1;
background: var(--vp-c-bg);
border: 1px solid var(--vp-c-divider);
border-radius: 8px;
padding: 12px;
display: flex;
flex-direction: column;
min-height: 250px;
}
canvas {
width: 100%;
height: 100%;
flex: 1;
}
.chart-legend {
display: flex;
gap: 16px;
justify-content: center;
margin-top: 8px;
font-size: 12px;
color: var(--vp-c-text-2);
}
.legend-item {
display: flex;
align-items: center;
gap: 6px;
}
.dot {
width: 8px;
height: 8px;
border-radius: 50%;
}
.dot.blue { background: #3b82f6; }
.dot.green { background: #22c55e; }
.dot.orange { background: #f97316; }
.scenario-tips {
margin-top: 16px;
background: rgba(59, 130, 246, 0.1);
border: 1px solid rgba(59, 130, 246, 0.2);
border-radius: 8px;
padding: 12px;
display: flex;
gap: 12px;
font-size: 14px;
line-height: 1.5;
color: var(--vp-c-text-1);
}
</style>