To debug how quickly different resources start up -- hugely important for application start up time. Used in https://www.scala-algorithms.com/

ResourceTimer.scala

import cats.effect.{IO, Resource}
import io.chrisdavenport.log4cats.SelfAwareStructuredLogger

import java.time.{Duration, Instant}

object ResourceTimer {

  implicit class RichResource[A](resource: Resource[IO, A]) {
    def measured(
        name: String,
    )(implicit logger: SelfAwareStructuredLogger[IO]): Resource[IO, A] =
      for {
        start <- Resource.liftF[IO, Instant](IO.delay(Instant.now()))
        allocated <- resource
        difference <- Resource.liftF[IO, Duration](
          IO.delay(Instant.now()).map(end => Duration.between(start, end)),
        )
        _ <- Resource.liftF[IO, Unit](logger.info(
          s"Resource '${name}' took $difference to start up.",
        ))
      } yield allocated
  }

}