@goa/goa/modules/cache-content-type/index.js

The Goa Source Code For Compilation Into @Goa/Koa That Includes Modules, Tests, Types And Dependencies.

import { contentType } from '@goa/mime-types'

export default type => {
  let mimeType = typeLRUCache.get(type)
  if (!mimeType) {
    mimeType = contentType(type)
    typeLRUCache.set(type, mimeType)
  }
  return mimeType
}

/**
 * Extends LRU base on hashlru.
 */
class LRU {
  constructor(max) {
    this.max = max
    this.size = 0
    this.cache = new Map()
    this._cache = new Map()
  }

  get(key, options = {}) {
    let item = this.cache.get(key)
    const { maxAge } = options
    // only call Date.now() when necessary
    let now
    function getNow() {
      now = now || Date.now()
      return now
    }
    if (item) {
      // check expired
      if (item.expired && getNow() > item.expired) {
        item.expired = 0
        item.value = undefined
      } else {
        // update expired in get
        if (maxAge !== undefined) {
          const expired = maxAge ? getNow() + maxAge : 0
          item.expired = expired
        }
      }
      return item.value
    }

    // try to read from _cache
    item = this._cache.get(key)
    if (item) {
      // check expired
      if (item.expired && getNow() > item.expired) {
        item.expired = 0
        item.value = undefined
      } else {
        // not expired, save to cache
        this._update(key, item)
        // update expired in get
        if (maxAge !== undefined) {
          const expired = maxAge ? getNow() + maxAge : 0
          item.expired = expired
        }
      }
      return item.value
    }
  }

  set(key, value, options = {}) {
    const { maxAge } = options
    const expired = maxAge ? Date.now() + maxAge : 0
    let item = this.cache.get(key)
    if (item) {
      item.expired = expired
      item.value = value
    } else {
      item = {
        value,
        expired,
      }
      this._update(key, item)
    }
  }

  keys() {
    const cacheKeys = new Set()
    const now = Date.now()

    for (const entry of this.cache.entries()) {
      checkEntry(entry)
    }

    for (const entry of this._cache.entries()) {
      checkEntry(entry)
    }

    function checkEntry(entry) {
      const key = entry[0]
      const item = entry[1]
      if (entry[1].value && (!entry[1].expired) || item.expired >= now) {
        cacheKeys.add(key)
      }
    }

    return Array.from(cacheKeys.keys())
  }

  _update(key, item) {
    this.cache.set(key, item)
    this.size++
    if (this.size >= this.max) {
      this.size = 0
      this._cache = this.cache
      this.cache = new Map()
    }
  }
}

const typeLRUCache = new LRU(100)


/**
 * @license MIT
 * [cache-content-type] Author dead_horse <dead_horse@qq.com>
 * https://github.com/node-modules/cache-content-type
 * [ylru] Author fengmk2
 * https://github.com/node-modules/ylru
 */