policies.md

Combining Policies!

The best part about rsxjs is that you can combine multiple resilience components together to create a robust resilience policy for your services. This is very useful as it allows you to specify very complex and distributed patterns of recovery without writing very much code at all.

Note: most of these examples utilize the flow utility from lodash. It is not required that you use this, but it is certainly very useful. If you wish to only use this util but not the rest of lodash, you can checkout lodash.flow.

This document contains some useful combinations of policies that are fairly common in applications.

Timeout + Locks

With the failFast option, you can ask a lock to simply error out if it is in a locked state. But sometimes, you may wish to wait a small period of time before accepting defeat. You can do this by combining a timeout component with either a mutex or a semaphore.

import { flow } from 'lodash'
import { Timeout, Mutex } from 'rsxjs'

async function doSexyOperation() {
  // TODO: do something on a shared resource
}

export const sexyOperation = flow(
  // by default, a mutex will not fail fast - it will wait
  // for its chance to obtain the lock
  Mutex.factory(),

  // the timeout component allows you to specify the time after
  // which you can fail the operation even if a lock is not obtained
  // in this case, we wait 1 second
  Timeout.factory({ timeout: 1000 }),
)( doSexyOperation )