nswbmw / koa-router-cache

Router cache middleware for koa.

koa-router-cache

Router cache middleware for koa@1.

Install

npm i koa-router-cache --save

Usage

cache(app, options)

Options:

• key: {String|GeneratorFunction} cache key. (Required)
• expire: {Number} expire time, in ms. (Required)
• get: {GeneratorFunction} custom getter function for getting data from cache. (Required)
• set: {GeneratorFunction} custom setter function for setting data to cache. (Required)
• passthrough: {GeneratorFunction} whether pass request through, return an object. (Required)
  • shouldCache: {Boolean} whether cache this result
  • shouldPass: {Boolean} whether pass this request through
• evtName: {String} event name for destroy cache. (Optional)
• destroy: {function} destroy cache. (Optional)
• pathToRegexp {Object} pathToRegexp options, see https://github.com/pillarjs/path-to-regexp#usage. (Optional)

Example

koa-router-cache build-in simple MemoryCache and RedisCache, also you can write by yourself.

MemoryCache

'use strict';
 
var app = require('koa')();
var cache = require('koa-router-cache');
var MemoryCache = cache.MemoryCache;
 
var count = 0;
 
app.use(cache(app, {
  'GET /': {
    key: 'cache:index',
    expire: 2 * 1000,
    get: MemoryCache.get,
    set: MemoryCache.set,
    passthrough: MemoryCache.passthrough,
    evtName: 'clearIndexCache',
    destroy: MemoryCache.destroy
  }
}));
 
app.use(function* () {
  if (this.path === '/') {
    this.body = count++;
    if (count === 3) {
      count = 0;
      this.app.emit('clearIndexCache');
    }  
  }
});
 
app.listen(3000, function () {
  console.log('listening on 3000.');
});

RedisCache

'use strict';

var app = require('koa')();
var cache = require('koa-router-cache');
var RedisCache = cache.RedisCache();// or RedisCache(client)

var count = 0;

app.use(cache(app, {
  'GET /': {
    key: 'cache:index',
    expire: 2 * 1000,
    get: RedisCache.get,
    set: RedisCache.set,
    passthrough: RedisCache.passthrough,
    evtName: 'clearIndexCache',
    destroy: RedisCache.destroy
  }
}));

app.use(function* () {
  if (this.path === '/') {
    this.body = {
      count: count++
    };
    if (count === 3) {
      count = 0;
      this.app.emit('clearIndexCache');
    }
  }
});

app.listen(3000, function () {
  console.log('listening on 3000.');
});

another usage:

// Guests share one index page cache
GET /': {
  key: 'cache:index',
  expire: 10 * 1000,
  get: MemoryCache.get,
  set: MemoryCache.set,
  destroy: MemoryCache.destroy,
  passthrough: function* passthrough(_cache) {
    // Guests
    if (!this.session || !this.session.user) {
      if (_cache == null) {
        return {
          shouldCache: true,
          shouldPass: true
        };
      }
      this.type = 'text/html; charset=utf-8';
      this.set('content-encoding', 'gzip');
      this.body = _cache;
      return {
        shouldCache: true,
        shouldPass: false
      };
    }
    // Logged-in users
    return {
      shouldCache: false,
      shouldPass: true
    };
  }
}

Test

npm test

License

MIT

koa-router-cache's Issues

有搭配redis使用的demo吗？

没用过redis不知道怎么搭配redis使用

POST url不支持吗

'POST /abc': {
passthrough: function* passthrough(_cache) {
console.log(_cache)
}
}

这样进不到console

关于执行流程的以后

'use strict';

var koa = require('koa');
var cache = require('koa-router-cache');
var MemoryCache = cache.MemoryCache;
var app = koa();
var count = 0;

app.use(cache(app, {
  'GET /' :{
    key: 'cache:index',
    expire: 5 * 1000 ,
    get: MemoryCache.get,
    set: MemoryCache.set,
    passthrough: MemoryCache.passthrough,
    evtName: 'clearIndexCache',
    destroy: MemoryCache.destroy 
  }
}));

app.use(function *() {
  var d = new Date();
  var strDate = (d.getMinutes()+1)+':'+ (d.getSeconds()+1);
  this.body = count++;
  console.log(strDate +' - '+ this.body);  // 这块每次通过浏览器请求的时候都会执行
  if(count === 5){
    count = 0;
    this.app.emit('clearIndexCache');
  }
});

app.listen(3000, function () {
  console.log('listening on 3000');
});

console.log(strDate +' - '+ this.body); // 这块每次通过浏览器请求的时候都会执行
并且每次输出的值也不一样

51:10 - 0
51:11 - 1
51:14 - 2
51:18 - 3
51:18 - 4
51:21 - 0
51:22 - 1
51:26 - 2
51:29 - 3
51:29 - 4

但是浏览器重展示的 数据5s 以内是一样的，有点糊涂了，求解惑

是我理解错了：使用 koa 搭建论坛系统 中的描述！

以上代码的意思是：缓存主页并 5 秒更新一次，第一次请求到来时缓存中间件中没有内容，所以传递到下一个中间件，此时将 this.body 赋值为 0 , count 变为 1，当中间件的 downstream 执行完毕后执行 upstream，此时将 this.body = 0 缓存到内存中，并设置 5 秒的生存期，所以，后续 5 秒之内的所有请求都会因命中缓存而返回 0 。5 秒过后，因为缓存中的内容已经过期被删除，所以下个请求到来时没有命中缓存，此时传递到下一个中间件将 this.body 赋值为 1 , count 变为 2，并更新缓存。直到当 count 变为 5 时，count 被重置为 0，并通过事件触发该路径对应的监听器立即删除缓存中的老数据，这样保证了缓存中的数据都是最新的。

我理解的是：每5s 刷新后，count 递增+1 依次出现，5s 没刷新这个数不会变。

conflict with `config` module's `get`

mark.
config has a method get confilct with koa-router-cache's get when use:

var config = require('config');
app.use(routerCache(app, config.routerCacheConf));

use `stream-to-array`

todo

0.3.0版本的有condition，1.x没有了，那么怎么设置condition呢