promise-memorize

Cache promise result for high-performance

Examples

View the ./examples directory for working examples.

Installation

$ npm install promise-memorize

API

memorize

• hasher generate cache key, default is use the first parameter for key

• ttl cache ttl, default is 0

return a new function for cache call, the function extends EventEmitter.

Cache promise for parallel call

const memorize = require('promise-memorize');
const fs = require('fs');
const path = require('path');
const readFile = function(file, encoding) {
  return new Promise((resolve, reject) => {
    fs.readFile(file, encoding, (err, data) => {
      console.info(`get file:${file} encoding:${encoding}`);
      if (err) {
        reject(err);
      } else {
        resolve(data);
      }
    });
  });
}
 
const readFileMemo = memorize(readFile);
const file = path.join(__dirname, './fs.js');
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
});
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  return readFileMemo(file);
}).then(buf => {
  console.info(`buf size:${buf.length}`);
});

[info] 2016-05-26T14:39:52.663Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:39:52.666Z buf size:818
[info] 2016-05-26T14:39:52.667Z buf size:818
[info] 2016-05-26T14:39:52.668Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:39:52.668Z buf size:818

Cache promise with ttl

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
});
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  return readFileMemo(file)
}).then(buf => {
  console.info(`buf size:${buf.length}`);
});

[info] 2016-05-26T14:40:16.117Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:40:16.121Z buf size:829
[info] 2016-05-26T14:40:16.122Z buf size:829
[info] 2016-05-26T14:40:16.123Z buf size:829

Cache promise with hasher and ttl

const readFileMemo = memorize(readFile, (file, encoding) => {
  return `${file}-${encoding}`;
}, 10 * 1000);
const file = path.join(__dirname, './fs.js');
readFileMemo(file, 'utf8').then(buf => {
  console.info(`buf size:${buf.length}`);
});
readFileMemo(file, 'ascii').then(buf => {
  console.info(`buf size:${buf.length}`);
  return readFileMemo(file, 'ascii');
}).then(buf => {
  console.info(`buf size:${buf.length}`);
});

[info] 2016-05-26T14:40:39.429Z get file:/promise-memorize/examples/fs.js encoding:utf8
[info] 2016-05-26T14:40:39.432Z buf size:912
[info] 2016-05-26T14:40:39.433Z get file:/promise-memorize/examples/fs.js encoding:ascii
[info] 2016-05-26T14:40:39.433Z buf size:912
[info] 2016-05-26T14:40:39.433Z buf size:912

setTTL

set the ttl for promise cache

const readFileMemo = memorize(readFile, 10 * 1000);
// 10000
console.info(readFileMemo.getTTL());
readFileMemo.setTTL(20 * 1000);
// 20000
console.info(readFileMemo.getTTL());

setStale

set the stale ttle for promise cache

const readFileMemo = memorize(readFile, 10 * 1000);
// 0
console.info(readFileMemo.getStale());
readFileMemo.setStale(2 * 1000);
// 2000
console.info(readFileMemo.getStale());

memorize.unmemorized

get original function

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
console.info(readFileMemo.unmemorized === readFile);
readFileMemo.unmemorized(file).then(buf => {
  console.info(`buf size:${buf.length}`);
});
readFileMemo.unmemorized(file).then(buf => {
  console.info(`buf size:${buf.length}`);
});

[info] 2016-05-26T14:41:22.741Z true
[info] 2016-05-26T14:41:22.746Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:41:22.748Z buf size:821
[info] 2016-05-26T14:41:22.748Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:41:22.748Z buf size:821

get

get the cache promise item

• key

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
 
readFileMemo.on('hit', key => {
  // {promise: Promise, hit: 1, createdAt: 1469200404168}
  const item = readFileMemo.get(key);
});
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  return readFileMemo(file);
}).then(buf => {
  console.info(`buf size:${buf.length}`);
});

delete

delete cache promise

• key

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
 
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  readFileMemo.delete(file);
  return readFileMemo(file);
}).then(buf => {
  console.info(`buf size:${buf.length}`);
});

[info] 2016-05-26T14:41:41.459Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:41:41.461Z buf size:783
[info] 2016-05-26T14:41:41.463Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:41:41.463Z buf size:783

clear

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
 
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  readFileMemo.clear();
  return readFileMemo(file);
}).then(buf => {
  console.info(`buf size:${buf.length}`);
});

[info] 2016-05-26T14:41:59.607Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:41:59.610Z buf size:778
[info] 2016-05-26T14:41:59.612Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:41:59.612Z buf size:778

size

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
 
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  console.info(`memorize size:${readFileMemo.size()}`);
});

[info] 2016-05-26T14:42:16.935Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:42:16.937Z buf size:722
[info] 2016-05-26T14:42:16.938Z memorize size:1

periodicClear

Set interval to check whether the promise is expired in order to avoid memory leak and the function's cache won't be clear by global periodicClear.

• interval chcek interval

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
 
readFileMemo.periodicClear(1 * 1000);
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  console.info(`memorize size:${readFileMemo.size()}`);
});
 
setTimeout(() => {
  console.info(`memorize size:${readFileMemo.size()}`);
}, 12 * 1000);

[info] 2016-05-26T14:42:32.977Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:42:32.979Z buf size:851
[info] 2016-05-26T14:42:32.980Z memorize size:1
[info] 2016-05-26T14:42:44.981Z memorize size:0

events

Adds the listener function to the end of the listeners array for the event named eventName.

• eventName The name of the event

• listener The callback function

const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
 
readFileMemo.on('hit', key => {
  console.info(`hit:${key}`);
});
readFileMemo.on('add', key => {
  console.info(`add:${key}`);
});
readFileMemo.on('delete', key => {
  console.info(`delete:${key}`);
});
readFileMemo.on('resolve', key => {
  console.info(`resolve:${key}`);
});
readFileMemo.on('reject', key => {
  console.info(`reject:${key}`);
});
 
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  readFileMemo.delete(file);
  readFileMemo('a.js');
});

[info] 2016-05-26T14:43:02.699Z add:/promise-memorize/examples/fs.js
[info] 2016-05-26T14:43:02.703Z get file:/promise-memorize/examples/fs.js encoding:undefined
[info] 2016-05-26T14:43:02.705Z resolve:/promise-memorize/examples/fs.js
[info] 2016-05-26T14:43:02.705Z buf size:1004
[info] 2016-05-26T14:43:02.705Z delete:/promise-memorize/examples/fs.js
[info] 2016-05-26T14:43:02.706Z add:a.js
[info] 2016-05-26T14:43:02.706Z get file:a.js encoding:undefined
[info] 2016-05-26T14:43:02.707Z reject:a.js

periodicClear

global periodic clear for all memorize function, please call it before any promise-memorize(If use this).

memorize.periodicClear(60 * 1000);
const readFileMemo = memorize(readFile, 10 * 1000);
const file = path.join(__dirname, './fs.js');
// promise-memorize function can not call periodicClear because global periodicClear has been called.
// readFileMemo.periodicClear(1 * 1000);
readFileMemo(file).then(buf => {
  console.info(`buf size:${buf.length}`);
  console.info(`memorize size:${readFileMemo.size()}`);
});

License

MIT