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  "readme": "# reusify\n\n[![npm version][npm-badge]][npm-url]\n\nReuse your objects and functions for maximum speed. This technique will\nmake any function run ~10% faster. You call your functions a\nlot, and it adds up quickly in hot code paths.\n\n```\n$ node benchmarks/createNoCodeFunction.js\nTotal time 53133\nTotal iterations 100000000\nIteration/s 1882069.5236482036\n\n$ node benchmarks/reuseNoCodeFunction.js\nTotal time 50617\nTotal iterations 100000000\nIteration/s 1975620.838848608\n```\n\nThe above benchmark uses fibonacci to simulate a real high-cpu load.\nThe actual numbers might differ for your use case, but the difference\nshould not.\n\nThe benchmark was taken using Node v6.10.0.\n\nThis library was extracted from\n[fastparallel](http://npm.im/fastparallel).\n\n## Example\n\n```js\nvar reusify = require('reusify')\nvar fib = require('reusify/benchmarks/fib')\nvar instance = reusify(MyObject)\n\n// get an object from the cache,\n// or creates a new one when cache is empty\nvar obj = instance.get()\n\n// set the state\nobj.num = 100\nobj.func()\n\n// reset the state.\n// if the state contains any external object\n// do not use delete operator (it is slow)\n// prefer set them to null\nobj.num = 0\n\n// store an object in the cache\ninstance.release(obj)\n\nfunction MyObject () {\n  // you need to define this property\n  // so V8 can compile MyObject into an\n  // hidden class\n  this.next = null\n  this.num = 0\n\n  var that = this\n\n  // this function is never reallocated,\n  // so it can be optimized by V8\n  this.func = function () {\n    if (null) {\n      // do nothing\n    } else {\n      // calculates fibonacci\n      fib(that.num)\n    }\n  }\n}\n```\n\nThe above example was intended for synchronous code, let's see async:\n```js\nvar reusify = require('reusify')\nvar instance = reusify(MyObject)\n\nfor (var i = 0; i < 100; i++) {\n  getData(i, console.log)\n}\n\nfunction getData (value, cb) {\n  var obj = instance.get()\n\n  obj.value = value\n  obj.cb = cb\n  obj.run()\n}\n\nfunction MyObject () {\n  this.next = null\n  this.value = null\n\n  var that = this\n\n  this.run = function () {\n    asyncOperation(that.value, that.handle)\n  }\n\n  this.handle = function (err, result) {\n    that.cb(err, result)\n    that.value = null\n    that.cb = null\n    instance.release(that)\n  }\n}\n```\n\nAlso note how in the above examples, the code, that consumes an instance of `MyObject`,\nreset the state to initial condition, just before storing it in the cache.\nThat's needed so that every subsequent request for an instance from the cache,\ncould get a clean instance.\n\n## Why\n\nIt is faster because V8 doesn't have to collect all the functions you\ncreate. On a short-lived benchmark, it is as fast as creating the\nnested function, but on a longer time frame it creates less\npressure on the garbage collector.\n\n## Other examples\nIf you want to see some complex example, checkout [middie](https://github.com/fastify/middie) and [steed](https://github.com/mcollina/steed).\n\n## Acknowledgements\n\nThanks to [Trevor Norris](https://github.com/trevnorris) for\ngetting me down the rabbit hole of performance, and thanks to [Mathias\nBuss](http://github.com/mafintosh) for suggesting me to share this\ntrick.\n\n## License\n\nMIT\n\n[npm-badge]: https://badge.fury.io/js/reusify.svg\n[npm-url]: https://badge.fury.io/js/reusify",
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