popular-cache

Popular Cache

An in-memory LRU cache with easy statistics and smart proxy mode.

Installation

npm install popular-cache --save

Basic Usage

var pcache = require('popular-cache');
	cache = pcache({
		maxSize: 500,
		maxAge: 1000 * 60 * 60	// in millisecond
	}),
	smallCache = pcache(50);	// or simply sets max size

// basic usage
cache.set("key", "value")
cache.get("key")
cache.del("key")	// delete key
cache.size()		// get size
cache.reset()   	// resets cache

cache.hits()		// get total hits
cache.misses()		// get total misses

// print the most popular keys and the number of hits
cache.popular(function(key, value, hits){
	console.log(key + ': ' + hits);
}, 5);

// print the most recently used keys and the number of hits
cache.recent(function(key, value, hits){
	console.log(key + ': ' + hits);
}, 10);

Proxy Mode

Proxy mode is as simple as telling popular-cache what you want and then you just get and get. Cache misses and concurrent requests are handled automatically.

// some time consuming process like HTTP request
var httpRequest = function(key, callback){
	setTimeout(function(){
		if(key=='popular-cache') callback('I am popular-cache');
		else callback('others');
	}, 1000);
}
var cache = pcache(50).proxy(httpRequest);

cache.get('popular-cache', function(value){
	console.log(value); // I am popular-cache
});
cache.get('another key', function(value){
	console.log(value); // others
});

The only difference in proxy mode is how the value is returned.

APIs

• set(key, value)

  • Stores a value.
  • Updates the "recently used"-ness of the entry.
  • Resets the age of the entry.

• get(key) (Normal Mode)

  • Gets a value for a given key. Returns null if not found.
  • Updates the "recently used"-ness of the entry.
  • Increases the hits of the entry

• get(key, function(value)) (Proxy Mode)

  • same as get(key) except how the value is returned. The callback function(value) is required in proxy mode to receive the value.

• del(key)

  • Deletes an entry for a given key.

• size()

  • Gets the current number of entries in the cache.

• reset()

  • Deletes all entries in the cache.

• hits()

  • Gets the total hits.

• misses()

  • Gets the total misses.

• recent(function(key, value, hits), [limit])

  • Iterate over recent used entries in reverse chronological order.
  • key: the key of the entry.
  • value: the value of the entry.
  • hits: the number of hits of the entry.
  • limit: optional, the maximum number of iterations.

• popular(function(key, value, hits), [limit])

  • Iterate over most popular entries in descending order of hits.
  • key: the key of the entry.
  • value: the value of the entry.
  • hits: the number of hits of the entry.
  • limit: optional, the maximum number of iterations.