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https://github.com/otbe/profilr

tiny profiling library
https://github.com/otbe/profilr

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tiny profiling library

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README 

        
# profilr



[![Build Status](https://travis-ci.org/otbe/profilr.svg?branch=master)](https://travis-ci.org/otbe/profilr)

[![Coverage Status](https://coveralls.io/repos/github/otbe/profilr/badge.svg?branch=master)](https://coveralls.io/github/otbe/profilr?branch=master)



*profilr* is a very tiny profiling library for your functions. It tracks down the execution time of each call and emits events.

It also supports functions that return a ```Promise```, so ```async```/```await``` can be tracked too. :)

It tries to add as less as possible overhead to the decorated or wrapped functions.



Basically *profilr* is unoptionated in what you're doing with this events. It does not log or evaluate something.

You have to add a consumer for this events. See the ```Consumers``` section.



## Install



```npm i profilr --save```



## Usage

*profilr* is written in TypeScript and typings are available. It can be used with TypeScript decorators, babel decorators and as a function wrapper.



```javascript

import { profile, useProfilr } from 'profilr';



useProfilr(true);



class MyService {

  constructor() {

    // fnName will be an empty string, but events will be labeled with 'getNumberOfRows'

    const getNumberOfRows = profile(() => 5, 'getNumberOfRows');



    // fnName will be 'getNumberOfColumns'

    const getNumberOfColumns = profile(function getNumberOfColumns() { return 5 });

  }



  @profile() // fnName will be 'expensiveComputation'

  expensiveComputation (): number {

    return 1*1;

  }



  @profile({ custom: 'foo' }) // fnName will be 'remoteApiCall'

  remoteApiCall (): Promise {

    return new Promise((resolve) => resolve(5));

  }

}

```

See tests for more usage information.



## Consumers

First consumer will be a react devtool like known from redux and mobx, but its not finished yet.



Stay tuned!



## API

All functions are available at the top level import.



### useProfilr

```

useProfilr(active: boolean)

```

Enables or disables *profilr*. The decorated or wrapped functions will still have some logic from *profilr*, but the overhead

is negligible. *profilr* is enabled by default.



### profile

```profile``` is a function wrapper or class method decorator which can be used to profile your function calls.



Function wrapper signatures:

```javascript

function profile (fn: T): T;

function profile (fn: T, label: string): T;

function profile (fn: T, options: ProfileOptions): T;

function profile (fn: T, label: string, options: ProfileOptions): T;

```



Class method decorators:

```javascript

function profile (): (target: any, propertyKey: string, descriptor: PropertyDescriptor) => PropertyDescriptor;

function profile (label: string): (target: any, propertyKey: string, descriptor: PropertyDescriptor) => PropertyDescriptor;

function profile (options: ProfileOptions): (target: any, propertyKey: string, descriptor: PropertyDescriptor) => PropertyDescriptor;

function profile (label: string, options: ProfileOptions): (target: any, propertyKey: string, descriptor: PropertyDescriptor) => PropertyDescriptor;

```



Parameter | Description

------------ | -------------

```fn``` | Function to be profiled

```label``` | Consumers can group several functions based on this string.

```options``` | Configuration object. For now it only holds a ```custom``` field, which can be used to send custom data to a consumer.



### registerEventCallback

```

function registerEventCallback(cb: EventCallback): () => void

```

Registers a callback for events produced by *profilr*. It returns a dispose function.

Only one parameter will be passed to the callback and it looks like this example:



```javascript

{

  id: 1,                            // each profiled function has an unique id

  fnName: 'map',                    // inferred name of function

  label: 'Part of Array prototype', // label

  duration: 50,                     // duration in ms

  result: [],                       // result of this call

  options: {

    custom: 'test'                  // custom data

  }

}

```



## Dependencies

*profilr* comes without dependencies, but it needs a [Reflect Metadata API](https://www.npmjs.com/package/reflect-metadata)

polyfill if your environment does not support it.