vcfvct/typescript-retry-decorator

A simple retry decorator for typescript with 0 dependency.

This is inspired by the Spring-Retry project. Written in Typescript, 100% Test Coverage.

Import and use it. Retry for Promise is supported as long as the runtime has promise(nodejs/evergreen-browser).

Install

npm install typescript-retry-decorator

Depending on your setup, you may need to enable experimentalDecorators flag in tsconfig.json.

Options

Option Name	Type	Required?	Default	Description
maxAttempts	number	Yes	-	The max attempts to try
backOff	number	No	0	number in `ms` to back off. If not set, then no wait
backOffPolicy	enum	No	FixedBackOffPolicy	can be fixed or exponential
exponentialOption	object	No	`{ maxInterval: 2000, multiplier: 2 }`	This is for the `ExponentialBackOffPolicy` The max interval each wait and the multiplier for the `backOff`. For `backoffStrategy`, more details below
doRetry	(e: any) => boolean	No	-	Function with error parameter to decide if repetition is necessary.
value	Error/Exception class	No	[ ]	An array of Exception types that are retryable.
useConsoleLogger	boolean	No	true	Print errors on console.
useOriginalError	throw original exception	No	false	`MaxAttemptsError` by default. if this is set to true, the `original` exception would be thrown instead.

Exponential options

The exponentialOption allows you to fine-tune the exponential backoff strategy using several options:

maxInterval: The maximum interval between two retries. The default value is 2000 ms.
multiplier: The multiplier to use to generate the next backoff interval from the last one. The default value is 2.
backoffStrategy: Optional. If specified, determines the strategy used to introduce "jitter" between retry intervals. For an explanation of the available strategies and why you might select one over the other, check out this article.
- ExponentialBackoffStrategy.FullJitter: The base backoff interval is multiplied by a random number between 0 and 1.
- ExponentialBackoffStrategy.EqualJitter: The backoff interval is (base interval / 2) + (random value between 0 and base interval / 2).

Example

import { Retryable, BackOffPolicy } from 'typescript-retry-decorator';

let count: number = 1;

class RetryExample {
  @Retryable({ maxAttempts: 3 })
  static async noDelayRetry() {
    console.info(`Calling noDelayRetry for the ${count++} time at ${new Date().toLocaleTimeString()}`);
    throw new Error('I failed!');
  }

  @Retryable({ 
    maxAttempts: 3, 
    value: [SyntaxError, ReferenceError]
  })
  static async noDelaySpecificRetry(): Promise<void> {
    console.info(`Calling noDelaySpecificRetry for the ${count++} time at ${new Date().toLocaleTimeString()}`);
    throw new SyntaxError('I failed with SyntaxError!');
  }

  @Retryable({ 
    maxAttempts: 3,
    backOff: 1000,
    doRetry: (e: Error) => {
      return e.message === 'Error: 429';
    }
   })
  static async doRetry() {
    console.info(`Calling doRetry for the ${count++} time at ${new Date().toLocaleTimeString()}`);
    throw new Error('Error: 429');
  }

  @Retryable({ 
    maxAttempts: 3,
    backOff: 1000,
    doRetry: (e: Error) => {
      return e.message === 'Error: 429';
    }
   })
  static async doNotRetry() {
    console.info(`Calling doNotRetry for the ${count++} time at ${new Date().toLocaleTimeString()}`);
    throw new Error('Error: 404');
  }

  @Retryable({
    maxAttempts: 3,
    backOffPolicy: BackOffPolicy.FixedBackOffPolicy,
    backOff: 1000
  })
  static async fixedBackOffRetry() {
    console.info(`Calling fixedBackOffRetry 1s for the ${count++} time at ${new Date().toLocaleTimeString()}`);
    throw new Error('I failed!');
  }

  @Retryable({
    maxAttempts: 3,
    backOffPolicy: BackOffPolicy.ExponentialBackOffPolicy,
    backOff: 1000,
    exponentialOption: { maxInterval: 4000, multiplier: 3 }
  })
  static async ExponentialBackOffRetry() {
    console.info(`Calling ExponentialBackOffRetry backOff 1s, multiplier=3 for the ${count++} time at ${new Date().toLocaleTimeString()}`);
    throw new Error('I failed!');
  }

  @Retryable({
    maxAttempts: 3,
    backOffPolicy: BackOffPolicy.ExponentialBackOffPolicy,
    backOff: 1000,
    exponentialOption: { maxInterval: 4000, multiplier: 2, backoffStrategy: ExponentialBackoffStrategy.EqualJitter }
  })
  static async ExponentialBackOffWithJitterRetry() {
    console.info(`Calling ExponentialBackOffWithJitterRetry backOff 1s, multiplier=2 for the ${count++} time at ${new Date().toLocaleTimeString()}`);
    throw new Error('I failed!');
  }
}

(async () => {
  try {
    resetCount();
    await RetryExample.noDelayRetry();
  } catch (e) {
    console.info(`All retry done as expected, final message: '${e.message}'`);
  }

  try {
    resetCount();
    await RetryExample.doRetry();
  } catch (e) {
    console.info(`All retry done as expected, final message: '${e.message}'`);
  }

  try {
    resetCount();
    await RetryExample.doNotRetry();
  } catch (e) {
    console.info(`All retry done as expected, final message: '${e.message}'`);
  }

  try {
    resetCount();
    await RetryExample.fixedBackOffRetry();
  } catch (e) {
    console.info(`All retry done as expected, final message: '${e.message}'`);
  }

  try {
    resetCount();
    await RetryExample.ExponentialBackOffRetry();
  } catch (e) {
    console.info(`All retry done as expected, final message: '${e.message}'`);
  }

  try {
    resetCount();
    await RetryExample.ExponentialBackOffWithJitterRetry();
  } catch (e) {
    console.info(`All retry done as expected, final message: '${e.message}'`);
  }

})();

function resetCount() {
  count = 1;
}

Run the above code with ts-node, then output will be:

Calling noDelayRetry for the 1 time at 4:12:49 PM
Calling noDelayRetry for the 2 time at 4:12:49 PM
Calling noDelayRetry for the 3 time at 4:12:49 PM
Calling noDelayRetry for the 4 time at 4:12:49 PM
I failed!
All retry done as expected, final message: 'Failed for 'noDelayRetry' for 3 times.'
Calling noDelayRetry for the 1 time at 4:12:49 PM
Calling noDelayRetry for the 2 time at 4:12:49 PM
Calling noDelayRetry for the 3 time at 4:12:49 PM
Calling noDelayRetry for the 4 time at 4:12:49 PM
I failed with SyntaxError!
All retry done as expected, final message: 'Failed for 'noDelaySpecificRetry' for 3 times.'
Calling doRetry for the 1 time at 4:12:49 PM
Calling doRetry for the 2 time at 4:12:50 PM
Calling doRetry for the 3 time at 4:12:51 PM
Calling doRetry for the 4 time at 4:12:52 PM
Error: 429
All retry done as expected, final message: 'Failed for 'doRetry' for 3 times.'
Calling doNotRetry for the 1 time at 4:12:52 PM
All retry done as expected, final message: 'Error: 404'
Calling fixedBackOffRetry 1s for the 1 time at 4:12:52 PM
Calling fixedBackOffRetry 1s for the 2 time at 4:12:53 PM
Calling fixedBackOffRetry 1s for the 3 time at 4:12:54 PM
Calling fixedBackOffRetry 1s for the 4 time at 4:12:55 PM
I failed!
All retry done as expected, final message: 'Failed for 'fixedBackOffRetry' for 3 times.'
Calling ExponentialBackOffRetry backOff 1s, multiplier=3 for the 1 time at 4:12:55 PM
Calling ExponentialBackOffRetry backOff 1s, multiplier=3 for the 2 time at 4:12:56 PM
Calling ExponentialBackOffRetry backOff 1s, multiplier=3 for the 3 time at 4:12:59 PM
Calling ExponentialBackOffRetry backOff 1s, multiplier=3 for the 4 time at 4:13:03 PM
I failed!
All retry done as expected, final message: 'Failed for 'ExponentialBackOffRetry' for 3 times.'
Calling ExponentialBackOffWithJitterRetry backOff 1s, multiplier=2 for the 1 time at 4:13:03 PM
Calling ExponentialBackOffWithJitterRetry backOff 1s, multiplier=2 for the 2 time at 4:13:03 PM
Calling ExponentialBackOffWithJitterRetry backOff 1s, multiplier=2 for the 3 time at 4:13:05 PM
Calling ExponentialBackOffWithJitterRetry backOff 1s, multiplier=2 for the 4 time at 4:13:09 PM
I failed!
All retry done as expected, final message: 'Failed for 'ExponentialBackOffWithJitterRetry' for 3 times.'

vcfvct / typescript-retry-decorator

readme

A simple retry decorator for typescript with 0 dependency.

Install

Options

Exponential options

Example