87 lines
2.5 KiB
JavaScript
87 lines
2.5 KiB
JavaScript
'use strict'
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const fs = require('fs')
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const path = require('path')
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// 日志总线：内存环形缓冲供管理窗口实时查看，同时落一份文件供现场排障。
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// 现场没有外网也没有终端，文件日志是事后定位问题的唯一线索。
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class LogBus {
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constructor(options = {}) {
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const { maxLines = 2000, file = null, maxFileBytes = 4 * 1024 * 1024 } = options
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this.maxLines = maxLines
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this.maxFileBytes = maxFileBytes
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this.lines = []
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this.listeners = new Set()
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// 子进程的输出是流式分片的，可能把一行拆到两次 data 事件里
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this.pending = new Map()
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this.stream = null
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if (file) this.openFile(file)
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}
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openFile(file) {
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try {
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fs.mkdirSync(path.dirname(file), { recursive: true })
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if (fs.existsSync(file) && fs.statSync(file).size > this.maxFileBytes) {
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// Windows 上 rename 到已存在的目标会失败，先删掉上一份轮转文件
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const rotated = `${file}.1`
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try {
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fs.rmSync(rotated, { force: true })
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} catch {
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// 删不掉就让 rename 失败，落到下面的「仅内存日志」兜底
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}
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fs.renameSync(file, rotated)
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}
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this.stream = fs.createWriteStream(file, { flags: 'a' })
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} catch (err) {
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this.stream = null
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this.push('console', `日志文件不可写，仅保留内存日志：${err.message}`)
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}
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}
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append(source, chunk) {
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const text = `${this.pending.get(source) || ''}${String(chunk)}`
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const parts = text.split(/\r?\n/)
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// 最后一段是没有换行的残行，留到下一次拼接
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this.pending.set(source, parts.pop() || '')
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for (const part of parts) this.push(source, part)
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}
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push(source, message) {
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const line = `[${new Date().toISOString()}] [${source}] ${message}`
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this.lines.push(line)
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if (this.lines.length > this.maxLines) {
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this.lines.splice(0, this.lines.length - this.maxLines)
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}
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if (this.stream) this.stream.write(`${line}\n`)
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for (const listener of this.listeners) {
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try {
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listener(line)
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} catch {
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// 单个订阅者出错不能拖垮日志链路
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}
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}
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}
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tail() {
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return this.lines.slice()
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}
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clear() {
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this.lines = []
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}
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onLine(listener) {
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this.listeners.add(listener)
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return () => this.listeners.delete(listener)
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}
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close() {
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if (this.stream) {
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this.stream.end()
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this.stream = null
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}
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}
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}
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module.exports = { LogBus }
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