Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, any subsequent attempt will be made after the 'delay' return by delayFunction(the input next attempt count start from 1). Returns None for no delay. A scheduler (eg context.system.scheduler) must be provided to delay each retry. You could provide a function to generate the next delay duration after first attempt, this function should never return null, otherwise an IllegalArgumentException will be thrown.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

If an attempt fails, the exception from the failure will be passed to the 'shouldRetry' predicate; if the predicate evaluates 'true', a retry will be attempted. This allows for short-circuiting in situations where the retries cannot be expected to succeed (e.g. in a situation where the legality of arguments can only be determined asynchronously).

Example usage:

// retry with backoff

protected val sendAndReceive: HttpRequest => Future[HttpResponse] = { (req) => ??? }
private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
  attempt = () => sendAndReceive(req),
  attempts = 10,
  delayFunction = attempted => Option(2.seconds * attempted),
  shouldRetry = ex => !ex.isInstanceOf[IllegalArgumentException]
)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made after the 'delay' return by delayFunction(the input next attempt count start from 1). Returns None for no delay. A scheduler (eg context.system.scheduler) must be provided to delay each retry. You could provide a function to generate the next delay duration after first attempt, this function should never return null, otherwise an IllegalArgumentException will be thrown.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

//retry with back off

protected val sendAndReceive: HttpRequest => Future[HttpResponse]
private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
  attempt = () => sendAndReceive(req),
  attempts = 10,
  delayFunction = attempted => Option(2.seconds * attempted)
)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made after 'delay'. A scheduler (eg context.system.scheduler) must be provided to delay each retry.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

protected val sendAndReceive: HttpRequest => Future[HttpResponse]
private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
  attempt = () => sendAndReceive(req),
  attempts = 10,
  delay = 2.seconds
)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will made with a backoff time if the preceding attempt failed and the 'shouldRetry' predicate, when applied to the failure's exception evaluates to 'true'. If the predicate evaluates to 'false', the failed attempt will be returned. This allows for short-circuiting in situations where the retries cannot be expected to succeed (e.g. in a situation where the legality of arguments can only be determined asynchronously).

If attempts are exhausted, the returned future is that of the last attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

protected def sendAndReceive(req: HttpRequest): Future[HttpResponse]
private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
  attempt = () => sendAndReceive(req),
  attempts = 10,
  minBackoff = 1.second,
  maxBackoff = 10.seconds,
  randomFactor = 0.2,
  shouldRetry = ex => !ex.isInstanceOf[IllegalArgumentException])

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made with a backoff time, if the previous attempt failed.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

protected val sendAndReceive: HttpRequest => Future[HttpResponse]
private val sendReceiveRetry: HttpRequest => Future[HttpResponse] = (req: HttpRequest) => retry[HttpResponse](
  attempt = () => sendAndReceive(req),
  attempts = 10,
  minBackoff = 1.seconds,
  maxBackoff = 2.seconds,
  randomFactor = 0.5
)

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made immediately if the preceding attempt failed and the 'shouldRetry' predicate, when applied to the failure's exception evaluates to 'true'. If the predicate evaluates to 'false', the failed attempt will be returned. This allows for short-circuiting in situations where the retries cannot be expected to succeed (e.g. in a situation where the legality of arguments can only be determined asynchronously).

If attempts are exhausted, the returned future is the that of the last attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage

def possiblyFailing(): Future[Something] = ???
val withRetry: Future[Something] = retry(
  attempt = possiblyFailing,
  attempts = 10,
  shouldRetry = { (ex) => ex.isInstanceOf[IllegalArgumentException] })

Given a function from Unit to Future, returns an internally retrying Future. The first attempt will be made immediately, each subsequent attempt will be made immediately if the previous attempt failed.

If attempts are exhausted the returned future is simply the result of invoking attempt. Note that the attempt function will be invoked on the given execution context for subsequent tries and therefore must be thread safe (not touch unsafe mutable state).

Example usage:

def possiblyFailing(): Future[Something] = ???
val withRetry: Future[Something] = retry(attempt = possiblyFailing, attempts = 10)