Function shouldShowCacheWarning

src/utils/cacheWarning.ts:82–128

(
  usage: Usage | null | undefined,
  querySource: string,
  threshold: number,
)

 * @returns 警告信息，如果不需要警告则返回 null
 */
export function shouldShowCacheWarning(
  usage: Usage | null | undefined,
  querySource: string,
  threshold: number,
): CacheHitRateInfo | null {
  const hitRate = calculateCacheHitRate(usage)

  // 无缓存数据
  if (hitRate === null) {
    return null
  }

  // 获取或初始化该 querySource 的状态
  let state = cacheWarningStateBySource.get(querySource)
  if (!state) {
    state = { lastHitRate: null, lastTimestamp: null }
    // Evict oldest entry when at capacity so the Map stays bounded
    if (cacheWarningStateBySource.size >= MAX_SOURCE_ENTRIES) {
      const oldestKey = cacheWarningStateBySource.keys().next().value
      if (oldestKey !== undefined) {
        cacheWarningStateBySource.delete(oldestKey)
      }
    }
    cacheWarningStateBySource.set(querySource, state)
  }

  // 首次请求不显示警告
  if (state.lastHitRate === null) {
    state.lastHitRate = hitRate
    state.lastTimestamp = Date.now()
    return null
  }

  // 计算趋势
  const trend = hitRate - state.lastHitRate

  // 更新状态
  state.lastHitRate = hitRate
  state.lastTimestamp = Date.now()

  // 检查是否需要警告
  if (hitRate < threshold) {
    return { hitRate, threshold, trend, shouldWarn: true }
  }

  return null
}

/**
 * 生成缓存警告消息