file-cache.js•3.81 kB
// src/core/file-cache.js
const fs = require('fs').promises;
const path = require('path');
const crypto = require('crypto');
/**
* 文件缓存管理器 - 缓存文件内容以减少I/O操作
*/
class FileCache {
/**
* @param {object} options 缓存选项
* @param {number} options.maxSize 最大缓存项数
* @param {number} options.ttl 缓存生存时间(ms)
*/
constructor(options = {}) {
this.maxSize = options.maxSize || 1000;
this.ttl = options.ttl || 5 * 60 * 1000; // 默认5分钟
this.cache = new Map();
this.stats = {
hits: 0,
misses: 0,
evictions: 0,
size: 0,
bytesStored: 0
};
}
/**
* 生成缓存键
* @param {string} filePath 文件路径
* @returns {string} 缓存键
*/
generateKey(filePath) {
return crypto.createHash('md5').update(filePath).digest('hex');
}
/**
* 获取文件内容，优先从缓存获取
* @param {string} filePath 文件路径
* @returns {Promise<string>} 文件内容
*/
async get(filePath) {
const key = this.generateKey(filePath);
if (this.cache.has(key)) {
const cacheEntry = this.cache.get(key);
// 检查缓存是否过期
if (Date.now() - cacheEntry.timestamp < this.ttl) {
// 检查文件是否被修改
try {
const stats = await fs.stat(filePath);
if (stats.mtimeMs <= cacheEntry.mtime) {
this.stats.hits++;
return cacheEntry.content;
}
} catch (error) {
// 如果无法获取文件状态，使用缓存内容
this.stats.hits++;
return cacheEntry.content;
}
}
// 缓存过期，删除
this.cache.delete(key);
this.stats.evictions++;
this.stats.size = this.cache.size;
this.stats.bytesStored -= cacheEntry.content.length;
}
// 缓存未命中，读取文件
this.stats.misses++;
try {
const content = await fs.readFile(filePath, 'utf8');
const stats = await fs.stat(filePath);
// 缓存新内容
this.set(key, {
content,
timestamp: Date.now(),
mtime: stats.mtimeMs,
size: content.length
});
return content;
} catch (error) {
throw new Error(`读取文件 ${filePath} 失败: ${error.message}`);
}
}
/**
* 设置缓存
* @param {string} key 缓存键
* @param {object} value 缓存值
*/
set(key, value) {
// 如果缓存已满，删除最旧的项
if (this.cache.size >= this.maxSize) {
const oldestKey = this.cache.keys().next().value;
const oldEntry = this.cache.get(oldestKey);
this.cache.delete(oldestKey);
this.stats.evictions++;
this.stats.bytesStored -= oldEntry.content.length;
}
this.cache.set(key, value);
this.stats.size = this.cache.size;
this.stats.bytesStored += value.content.length;
}
/**
* 清除缓存
* @param {string} [filePath] 特定文件路径，不提供则清除所有缓存
*/
invalidate(filePath) {
if (filePath) {
const key = this.generateKey(filePath);
if (this.cache.has(key)) {
const entry = this.cache.get(key);
this.stats.bytesStored -= entry.content.length;
this.cache.delete(key);
this.stats.size = this.cache.size;
}
} else {
this.cache.clear();
this.stats.size = 0;
this.stats.bytesStored = 0;
}
}
/**
* 获取缓存统计信息
* @returns {object} 统计信息
*/
getStats() {
return {
...this.stats,
hitRate: this.stats.hits / (this.stats.hits + this.stats.misses) || 0,
bytesStoredMB: Math.round(this.stats.bytesStored / 1024 / 1024 * 100) / 100
};
}
}
module.exports = FileCache;