84 lines
2.0 KiB
Markdown
84 lines
2.0 KiB
Markdown
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Memoize functions results using an lru-cache.
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## Installation
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```
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npm i lru-memoizer --save
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```
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## Intro
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This module uses an [lru-cache](https://github.com/isaacs/node-lru-cache) internally to cache the results of an async function.
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The `load` function can have N parameters and the last one must be a callback. The callback should be an errback (first parameter is `err`).
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The `hash` function purpose is generate a custom hash for storing results. It has all the arguments applied to it minus the callback, and must return an string synchronous.
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The `freeze` option (defaults to **false**) allows you to deep-freeze the result of the async function.
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The `clone` option (defaults to **false**) allows you to deep-clone the result every time is returned from the cache.
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## Usage
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```javascript
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var memoizer = require('lru-memoizer');
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var memoizedGet = memoizer({
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//defines how to load the resource when
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//it is not in the cache.
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load: function (options, callback) {
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request.get(options, callback);
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},
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//defines how to create a cache key from the params.
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hash: function (options) {
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return options.url + qs.stringify(options.qs);
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},
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//all other params for the LRU cache.
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max: 100,
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maxAge: 1000 * 60
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});
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memoizedGet({
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url: 'https://google.com',
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qs: { foo: 123 }
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}, function (err, result, body) {
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//console.log(body);
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})
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```
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## Sync lru-memoizer
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Use `memoizer.sync` to cache things that are slow to calculate or methods returning promises.
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```
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var memoizer = require('lru-memoizer');
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var memoizedGet = memoizer.sync({
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//defines how to load the resource when
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//it is not in the cache.
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load: function (params) {
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//return something_hard_to_compute;s
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},
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//defines how to create a cache key from the params.
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hash: function (params) {
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return params.foo;
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},
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//all other params for the LRU cache.
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max: 100,
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maxAge: 1000 * 60
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});
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```
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## Similar modules
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This module is very similar to [async-cache](https://github.com/isaacs/async-cache), the main difference is the `hash` function.
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## License
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MIT 2016 - José F. Romaniello
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