dont-collide

A throttle for functions that calls external sources. Developed in order to prevent "Connection refused" errors.

Use it to prevent collisions and "denial of service" when sending data in a loop to an external source.

• Easy to use and fast to implement
• Ultra lightweight
• Option to return function data as an array when finished or to return data for every call
• Suppport for returning data through asyncronous callbacks

Basic usage

Use npm to install the module:

	npm install dont-collide

Then use dontCollide like this:

var dontCollide = require('dont-collide');

var dc = dontCollide();

dc.throttle(
	function(p1, p2, p3) { 
		console.log('Fired: ' + p1 + ' - ' + p2 + ' - ' + p3);	
	}
	,1,2,3);

/*
Outputs

Fired: 1 - 2 - 3

*/

Usage where return data is returned is summed up in an array

var dontCollide = require('dont-collide');

let cb = function(results) {
	for(var i = 0; i < results.length; i++){
		console.log("CorrelationId: " + results[i].correlationId + "\nResult: " + results[i].result + "\n\n");
	}
}

var dc = dontCollide({ finalize: cb });

dc.throttle({ correlationId: 20, fn: function(){ return 'Mr. T' }});
dc.throttle({ correlationId: 30, fn: function(){ return 'Face' }});
dc.throttle({ correlationId: 40, fn: function(){ return 'Hannibal' }});

/*
Outputs:

CorrelationId: 20
Result: Mr. T


CorrelationId: 30
Result: Face


CorrelationId: 40
Result: Hannibal
*/

Usage where return data is provided through callback

var dontCollide = require('dont-collide');

let cb = (result) => {
		console.log("CorrelationId: " + result.correlationId + "\nResult: " + result.result + "\n\n");
}

var dc = dontCollide();

dc.throttle({ correlationId: 20, fn: function(){ return 'Mr. T' }, callback: cb});
dc.throttle({ correlationId: 30, fn: function(){ return 'Face' }, callback: cb});
dc.throttle({ correlationId: 40, fn: function(){ return 'Hannibal' }, callback: cb});

/*
Outputs:

CorrelationId: 20
Result: Mr. T


CorrelationId: 30
Result: Face


CorrelationId: 40
Result: Hannibal
*/

Usage for asynchronous calls

var dontCollide = require('dont-collide');

let cb = function(greeting, cid, rs) {
	console.log(cid + ": " + greeting + " " + rs);
}


const dc = dontCollide();

dc.throttle({ correlationId: 20, fn: function(greeting, cid, c) { setTimeout(() => { c(greeting, cid, 'Mr. T'); }, 1 ); }, asyncCallback: cb }, 'Hi');
dc.throttle({ correlationId: 30, fn: function(greeting, cid, c) { setTimeout(() => { c(greeting, cid, 'Hannibal'); }, 100 ); }, asyncCallback: cb}, 'Hello');
dc.throttle({ correlationId: 40, fn: function(greeting, cid, c) { setTimeout(() => { c(greeting, cid, 'Face'); }, 50 ); }, asyncCallback: cb}, 'Good day');

/*
Outputs:

20: Hi Mr. T
40: Good day Face
30: Hello Hannibal

*/

Instance options

You can of course provide options for setting up dont-collide.

interval

Number

Default: 1

Time gap in miliseconds between each function call.

var dc = dontCollide({ interval: 1000 });

This sets the interval to one call each second.

finalize

Function

Default: Empty function

The callback function which is called when all function calls are completed.

var dc = dontCollide({ finalize: function(results) { console.log(result.correlationId + " - " + result.result); } });

This sets the interval to one call each second.

Throttle options

correlationId

String or number

Default: 0

An id to recognize your request on. Useful if some function call takes longer than others

dc.throttle({ correlationId: 20, fn: function(){ return 'Mr. T' }});

fn

Function

Required.

The function you wish to execute with throttling

dc.throttle({ fn: function(num1, num2){ console.log(num1 + num2) }}, 5, 10);

/*
Outputs

15
*/

Actually, if you don't wish to set any other options, you can just send the function alone.

dc.throttle(function(num1, num2){ console.log(num1 + num2) }, 5, 10);

/*
Outputs

15
*/

You can always pass parameters by sending a parameter list after the options (or your function).

asyncCallback

Function

Default: null

When using asyncCallback two more parameters are added to the parameter list of your function call. The correlationId and the async callback.

dc.throttle({ correlationId: 40, fn: function(greeting, cid, c) { setTimeout(() => { c(greeting, cid, 'Face'); }, 50 ); }, asyncCallback: function(greeting, cid, rs){console.log(cid + ": " + greeting + " " + rs);}}, 'Good day');

/*
Outputs

30: Hello Hannibal
*/

callback

Function

Default: null

A function that is called with the result for every execution. If this is set for a call to throttle, then the result will not go into the results that is send to the finalize function.

dc.throttle({ fn: function(){ return 'Mr. T' }, callback: function(rs){ console.log(rs.result); } });

/*
Outputs

Mr. T
*/

Tests

To run tests on this module, make sure that the modules for the tests are installed

	npm install dont-collide --dev

Then run:

	npm test

#Release notes

• 1.0.1 - Changed default finalize prop from arrow function to function.
• 1.0.0 - First working version

#Keywords

• throttle
• throttling
• function queue
• method queue
• queue
• dont-collide

License

The MIT License (MIT)

Copyright (c) 2016 Thorbjørn Gliese Jelgren (The Right Foot, www.therightfoot.dk)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.