ringo-cache

cache.js

export("Cache");

function Cache() {
	var self = this;
	this.size = 0;
	this.map = {};

	function wrap(f, name, period, that) {
		return function () {
			var t = new Date().getTime();
			var args = Array.prototype.slice.call(arguments);  
			var key = name + ":" + args.toJSON(); //TODO use hash instead of full JSON representation
			var r;
			var value = that.map[key];
			if(value) {
				r = value.result;
				if(t < value.expires) {
					return r;
				}
				//log.info("Overwriting " + key);
			}
			try {
				//log.info("Added " + key);
				r = f.apply(this, arguments);
				that.map[key] = { result: r,	expires: t + period	};
				if(!value) that.size ++;
				//log.info(that.size());
			} catch(e) {
				//log.info("catch " + key);
				// if the underlying call fails, log the error
				//log.info(e.toJSON());
				// if we have a cached value, hide the exception, otherwise throw it
				if(!r) throw e;
			}
			return r;
		};
	}
	
	this.cache = function(p, name, period) {
    if(p instanceof Function)
      return wrap(p, name, period, this);   
    var prefix = name ? name + "." : "";
    for(var key in p) {
      var value = p[key];
      if(value instanceof Function) {
        p[key] = wrap(value, prefix + key, period, this);
      }
    }
    return p;
  }
		
	this.purge = function() {
		var t = new Date().getTime();
		for(var key in self.map) {
			var value = self.map[key];
			if(t > value.expires) {
				//log.info("purged " + key);
				delete self.map[key];
				self.size --;
			}
		}
	}
}