Alzheimer
Alzheimer is a JavaScript memoization library for Node with support for streams and promises.
How can I speed up a slow function?
You might want to memoize it.
This means you put a wrapper around it that caches the function's result
so it can answer subsequent calls faster.
What does a memoization library do?
A memoization library such as Alzheimer creates this wrapper for you.
How does Alzheimer differ from other memoization libraries?
The difference from other libraries such as
memo,
memoize
and memoizer
is that Alzheimer also memoizes:
Usage
Installation
$ npm install alzheimer
API
The alzheimer
module exposes an object with a single function remember(func, options)
.
Call remember
with your function to retrieve a memoized version.
Memoized items can expire by setting options
to { forget: { after: 60000 } }
,
where 60000
is the number of milliseconds an item can live.
Examples
Memoizing computation-intensive functions
This example illustrates how Alzheimer speeds up results by memoizing a function.
// Calculates a computation-intensive hash { for var i = 1 result = 0; i < 20000; i++ for var j = 2; j < 10000; j++ result = result + number * i % j + 13; return result;} // Both calculations below take equal time // Now create a memoized version of the functionvar remember = remember;computeBigHash = ;// Only the first calculation below takes some time,// The second and third ones return immediately
Memoizing promises and streams
This example shows how Alzeimer can cache a stream resulting from a promise. The stream is actually played back, as the HTTP response is cached to disk. We also see that the cache can be kept fresh by demanding expiration.
var http = promiscuous = /* or any Promise/A+ library */ remember = remember; // Creates a promise to a stream of the specified HTTP resource { console; var deferred = promiscuous; http; return deferredpromise;}; // Memoize results of the `request` function for 2500 msvar rememberedRequest = ; // The first request will require a download; // This request won't require a download; // This request won't require a download; // This request will require a download again, since the cache result expired;
License
Copyright ©2013 Ruben Verborgh – MIT Licensed