retrying-promise

Create fault tolerant promises that retry upon failure according to a retry strategy.

The implementation of the retry strategies reuses code from the node-retry project.

Usage

Install retrying-promise:

npm install retrying-promise

Import retrying-promise:

const retryPromise = require('retrying-promise');

The constant retryPromise is a function that returns a promise. Use this function similar to how you call the new Promise() constructor, but pass it a function that takes three instead of two functions as arguments: resolve, retry and reject.

var promise = retryPromise(function (resolve, retry, reject) {

    resolve(result);  // the promise resolves normally

    retry(error);     // the promise failed and a retry may be attempted

    reject(error);    // the promise failed and no retry should be attempted

});

Call the resolve function when the promise resolves normally.

Call the retry function when the promise failed and a retry may be attempted.

Call the reject function when the promise failed and no retry should be attempted.

Test

Install Mocha.

sudo npm install -g mocha

Run tests:

npm test

API Reference

Author: Wouter Van den Broeck
Copyright: 2016

module.exports([options], executor) ⇒ Promise ⏏

Returns a promise that conditionally tries to resolve multiple times, as specified by the retry policy.

Kind: Exported function

| Param | Type | Description | | --- | --- | --- | | [options] | retryPolicy | Either An object that specifies the retry policy. | | executor | retryExecutor | A function that is called for each attempt to resolve the promise. |

module.exports~createTimeout(attempt, opts) ⇒ number

Get a timeout value in milliseconds.

Kind: inner method of module.exports
Returns: number - The timeout value in milliseconds.

| Param | Type | Description | | --- | --- | --- | | attempt | number | The attempt count. | | opts | Object | The options. |

module.exports~retryPolicy : Object

An object that specifies the retry policy.

Kind: inner typedef of module.exports
Properties

| Name | Type | Default | Description | | --- | --- | --- | --- | | retries | number | 10 | The maximum amount of times to retry the operation. | | factor | number | 2 | The exponential factor to use. | | minTimeout | number | 1000 | The number of milliseconds before starting the first retry. | | maxTimeout | number | Infinity | The maximum number of milliseconds between two retries. | | randomize | boolean | false | Randomizes the timeouts by multiplying with a factor between 1 to 2. |

module.exports~retryExecutor : function

The function that is called for each attempt to resolve the promise.

Kind: inner typedef of module.exports

| Param | Type | Description | | --- | --- | --- | | resolveFn | function | To be called when the promise resolves normally. | | retryFn | function | To be called when the promise failed and a retry may be attempted. | | [rejectFn] | function | To be called when the promise failed and no retry should be attempted. |

© 2016, Wouter Van den Broeck