JarCastingFailurewall
This is a library to protect applications against failures, and helpful in developing stable, responsive and resilient systems.
Failurewall is inspired by Hystrix and adapted for scala.concurrent.Future.
Getting Started
You should add the following dependency.
libraryDependencies += "com.okumin" %% "failurewall-core" % "0.4.0"
If you are using Akka 2.4, you can use failurewall-akka. failurewall-akka provides the following failurewalls.
- circuit breaker
- retry with backoff
- timeout
libraryDependencies += "com.okumin" %% "failurewall-akka" % "0.4.0"
If you are using Akka 2.3, see also failurewall-akka23.
How to use
As a Proxy
Failurewall is simple to use, wrapping scala.concurrent.Future to be protected. Each failurewall has abilities to handle failures.
object HttpClient {
def get(url: String): Future[Response] = ???
}
val wall: Failurewall[Response, Response] = ???
val response: Future[Response] = wall.call(HttpClient.get("http://okumin.com/"))
Composability
Failurewalls has their own ability, e.g. retrying, checking rate limits and throttling. Failurewall#compose makes Failurewalls decorate such features.
val wallSina: Failurewall[Int, String] = ???
val wallRose: Failurewall[Int, Int] = ???
val wallMaria: Failurewall[Double, Int] = ???
val walls: [Double, String] = wallSina compose wallRose compose wallMaria
Built-in walls(failurewall-core)
RetryFailurewall
Retries on temporary failures.
val wall = RetryFailurewall[Response](10, executionContext)
wall.call(Future.failed(new RuntimeException)) // retry 10 times
StdSemaphoreFailurewall
Keeps resource usage constant.
val wall = StdSemaphoreFailurewall[Response](10, executionContext)
val results = (1 to 100).map { _ =>
// fails immediately while other 10 calls are running
wall.call(doSomeOperation())
}
StopwatchFailurewall
Measures the execution time.
val wall = StopwatchFailurewall[Response](executionContext)
wall.call(doSomeOperation()) // returns Future[(Try[Response], FiniteDuration)]
Built-in walls(failurewall-akka)
AkkaCircuitBreakerFailurewall
Prevents a failure from leading to cascading other failures.
// has a little complicated constructor
val wall: AkkaCircuitBreakerFailurewall[Response] = ???
val results = (1 to 100).map { _ =>
// fail-fast after failure times exceeds the threshold
wall.call(Future {
throw new RuntimeException
})
}
AkkaRetryFailurewall
Retries with backoff on temporary failures.
val backoffStrategy = ExponentialBackoffStrategy(
minBackoff = 100.millis,
maxBackoff = 10.seconds,
multiplier = 2.0
)
val wall = AkkaRetryFailurewall[Response](
10,
backoffStrategy,
akkaScheduler,
executionContext
)
// retry 10 times with exponential backoff
wall.call(Future.failed(new RuntimeException))
AkkaTimeoutFailurewall
Times out when it takes some duration.
val wall = AkkaTimeoutFailurewall[String](5.seconds, akkaScheduler, executionContext) {
logger.error("Timed out.")
}
// fails with FailurewallException
wall.call(Future {
Thread.sleep(10000)
"mofu"
})
