@zhanghongping/json-sage-workflow-cli/dist/core/cache.js

An intelligent JSON processing workflow system with improved error handling and configuration

class SmartCache {
  constructor(options = {}) {
    this.maxSize = options.maxSize || 1024 * 1024; // 默认1MB
    this.ttl = options.ttl || 3600000; // 默认1小时
    this.smartPruning = options.smartPruning || false;
    this.cache = new Map();
    this.metadata = new Map();
    this.totalSize = 0;
  }
  set(key, value) {
    const size = this.calculateSize(value);

    // 检查单个项目大小
    if (size > this.maxSize) {
      return false;
    }

    // 如果需要，清理空间
    this.ensureSpace(size);

    // 存储数据和元数据
    this.cache.set(key, value);
    this.metadata.set(key, {
      size,
      accessCount: 0,
      lastAccessed: Date.now(),
      expires: Date.now() + this.ttl
    });
    this.totalSize += size;
    return true;
  }
  get(key) {
    // 检查是否存在
    if (!this.cache.has(key)) {
      return undefined;
    }
    const metadata = this.metadata.get(key);

    // 检查是否过期
    if (Date.now() > metadata.expires) {
      this.delete(key);
      return undefined;
    }

    // 更新访问统计
    metadata.accessCount++;
    metadata.lastAccessed = Date.now();
    metadata.expires = Date.now() + this.ttl;
    return this.cache.get(key);
  }
  delete(key) {
    if (this.cache.has(key)) {
      const metadata = this.metadata.get(key);
      this.totalSize -= metadata.size;
      this.cache.delete(key);
      this.metadata.delete(key);
      return true;
    }
    return false;
  }
  clear() {
    this.cache.clear();
    this.metadata.clear();
    this.totalSize = 0;
  }
  calculateSize(value) {
    try {
      const str = JSON.stringify(value);
      return str.length * 2; // 假设每个字符占用2字节
    } catch (e) {
      // 如果无法序列化（例如循环引用），返回保守估计
      return 1024;
    }
  }
  ensureSpace(requiredSize) {
    if (this.totalSize + requiredSize <= this.maxSize) {
      return;
    }

    // 获取所有项目的评分
    const scores = Array.from(this.metadata.entries()).map(([key, meta]) => ({
      key,
      score: this.calculateScore(meta)
    }));

    // 按分数排序（分数低的先删除）
    scores.sort((a, b) => a.score - b.score);

    // 删除项目直到有足够空间
    for (const item of scores) {
      if (this.totalSize + requiredSize <= this.maxSize) {
        break;
      }
      this.delete(item.key);
    }
  }
  calculateScore(metadata) {
    if (!this.smartPruning) {
      return metadata.lastAccessed; // 简单的LRU
    }

    // 考虑多个因素的智能评分
    const age = Date.now() - metadata.lastAccessed;
    const accessFrequency = metadata.accessCount / age;
    const sizeScore = 1 / metadata.size;
    return accessFrequency * 0.5 +
    // 访问频率权重
    sizeScore * 0.3 +
    // 大小权重
    1 / age * 0.2 // 年龄权重
    ;
  }
  getStats() {
    let totalAccessCount = 0;
    let oldestAccess = Date.now();
    let newestAccess = 0;
    this.metadata.forEach(meta => {
      totalAccessCount += meta.accessCount;
      oldestAccess = Math.min(oldestAccess, meta.lastAccessed);
      newestAccess = Math.max(newestAccess, meta.lastAccessed);
    });
    return {
      totalSize: this.totalSize,
      itemCount: this.cache.size,
      utilization: this.totalSize / this.maxSize * 100,
      averageAccessCount: this.cache.size ? totalAccessCount / this.cache.size : 0,
      oldestAccess: new Date(oldestAccess).toISOString(),
      newestAccess: new Date(newestAccess).toISOString()
    };
  }
}
module.exports = {
  SmartCache
};