retry-client

Client that retries any function until no error is thrown and (if desired) function did not timeout. Alternatively, a timeout can be set for a single attempt to resolve the function.

Installation

Use npm to install retry-client.

npm install retry-client

Usage

Retry-client can be used according to its JSDocs definition. Initiate retry-client once and call retry to retry to resolve a function or timeout to try to resolve within timeout period.

const RetryClient = require('retry-client');
const settings = {}; // see below to see available settings
const retryClient = new RetryClient(settings);

new RetryClient(settings)

Initiate RetryClient once. retry and timeout will use the settings provided in RetryClient. The following settings can be passed into the settings object:

• retryHandler (function) function to be called on retry. Defaults to () => null.
• errorHandler (function) function to be called on error after last attempt. Defaults to () => null.
• fixedBackOff (number) fixed back off period (ms). If provided a fixed back off period is used in between retry attempts. Defaults to 0 (no fixed back off)
• minimumBackOff (number) minimum back off period (ms). This back off period is used on first retry attempt. Defaults to 100.
• backOffExponent (number) exponent to be used to determine next back off period. Defaults to 1.5.
• maximumBackOff (number) maximum back off period (ms). Back off period will never exceed the provided value. Defaults to 10000.
• maximumRetryCount (number) maximum number of retries. Defaults to 5.
• timeout (number) maximum time allowed to resolve a single iteration (ms). When provided an attempt to resolve functionToCall will be considered as failed if the timeout is exceeded. Defaults to 0 (no timeout).

Both retryHandler and errorHandler will receive the following input when called:

{
  totalDuration: Number, // milliseconds
  iterationDuration: Number, // milliseconds
  iteration: Number, // iteration counter
  remaining: Number, // remaining iterations
  error: Error // details of the error of the regarding iteration
}

retryClient.retry(functionToCall, functionInput)

Attempts to successfully resolve functionToCall with the provided functionInput. Stops retrying when function resolved successfully once.

Example:

const RetryClient = require('retry-client');
const settings = { maximumRetryCount: 3 };
const retryClient = new RetryClient(settings);
const functionToCall = (inputA, inputB, inputC) => {
  //do something
  return `${inputA} - ${inputB} - ${inputC}`;
};
const result = retryClient.retry(functionToCall, ['A', 'B', 'C']);

If successfully resolved within 3 retries, result is: 'A - B - C' Otherwise error of last attempt is thrown.

retryClient.safeRetry(functionToCall, functionInput)

Attempts to successfully resolve functionToCall with the provided functionInput. Stops retrying when function resolved successfully once. Returns null when last attempt failed.

Example:

const RetryClient = require('retry-client');
const settings = { maximumRetryCount: 3 };
const retryClient = new RetryClient(settings);
const functionToCall = (inputA, inputB, inputC) => {
  //do something
  return `${inputA} - ${inputB} - ${inputC}`;
};
const result = retryClient.safeRetry(functionToCall, ['A', 'B', 'C']);

If successfully resolved within 3 retries, result is: 'A - B - C' Otherwise return null.

retryClient.timeout(functionToCall, functionInput)

Attempts to successfully resolve functionToCall with the provided functionInput within the provided timeout (setting).

Example:

const RetryClient = require('retry-client');
const settings = { timeout: 1000 };
const retryClient = new RetryClient(settings);
const functionToCall = (inputA, inputB, inputC) => {
  //do something
  return `${inputA} - ${inputB} - ${inputC}`;
};
const result = retryClient.timeout(functionToCall, ['A', 'B', 'C']);

If successfully resolved within 1000 ms, result is: 'A - B - C' Otherwise the following error is thrown: Timed out after 1000 ms.

retryClient.safeTimeout(functionToCall, functionInput)

Attempts to successfully resolve functionToCall with the provided functionInput within the provided timeout (setting). When not resolved the function returns null.

Example:

const RetryClient = require('retry-client');
const settings = { timeout: 1000 };
const retryClient = new RetryClient(settings);
const functionToCall = (inputA, inputB, inputC) => {
  //do something
  return `${inputA} - ${inputB} - ${inputC}`;
};
const result = retryClient.safeTimeout(functionToCall, ['A', 'B', 'C']);

If successfully resolved within 1000 ms, result is: 'A - B - C' Otherwise return null.