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/*
* Copyright 2023-2024 John A. De Goes and the ZIO Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package zio.macros
import zio._
/**
* A `ServiceReloader` is a "registry" of services, allowing services to be
* reloaded dynamically. You can create a reloadable version of your service by
* using the `reloadable` operator on `ZLayer`. Then just call
* `ServiceLoader.reload` to reload the service.
*/
trait ServiceReloader {
/**
* Registers the specified service with a layer that constructs the service.
* Returns an implementation of the service that is backed by a `ScopedRef`
* which will handle reloading the service. Fails with a
* `ServiceInitializationError` exception if an error occurs while acquiring
* the service.
*/
def register[A: Tag: IsReloadable](serviceLayer: ZLayer[Any, Any, A]): IO[ServiceReloader.Error, A]
/**
* Reloads the specified service, releasing any resources associated with the
* service and acquiring a new service. Fails with a
* `ServiceInitializationError` exception if an error occurs reloading the
* service or a `ServiceNotRegistered` exception if a layer constructing the
* service was never registered.
*/
def reload[A: Tag]: IO[ServiceReloader.Error, Unit]
}
object ServiceReloader {
sealed trait Error extends Throwable
final case class ServiceInitializationError(error: Any) extends Error
final case class ServiceNotRegistered(tag: LightTypeTag) extends Error
/**
* The live implementation of the `ServiceReloader` service.
*/
val live: ZLayer[Any, Nothing, ServiceReloader] =
ZLayer.scoped {
for {
ref <- Ref.Synchronized.make[Map[LightTypeTag, (ZLayer[Any, Any, Any], ScopedRef[Any])]](Map.empty)
scope <- ZIO.scope
} yield new ServiceReloader {
def register[A: Tag: IsReloadable](serviceLayer: ZLayer[Any, Any, A]): IO[ServiceReloader.Error, A] =
ref.modifyZIO { map =>
val tag = Tag[A].tag
map.get(tag) match {
case Some((_, scopedRef)) =>
scope.extend {
scopedRef
.set(serviceLayer.build.map(_.unsafe.get(tag)(Unsafe.unsafe)))
.foldZIO(
error => ZIO.fail(ServiceInitializationError(error)),
_ => scopedRef.get.map(a => (a.asInstanceOf[A], map))
)
}
case None =>
scope.extend {
ScopedRef
.fromAcquire(serviceLayer.build.map(_.unsafe.get[A](tag)(Unsafe.unsafe)))
.foldZIO(
error => ZIO.fail(ServiceInitializationError(error)),
scopedRef =>
ZIO.succeed(
(
IsReloadable[A].reloadable(scopedRef),
map.updated(tag, (serviceLayer, scopedRef.asInstanceOf[ScopedRef[Any]]))
)
)
)
}
}
}
def reload[A: Tag]: IO[ServiceReloader.Error, Unit] =
ref.modifyZIO { map =>
val tag = Tag[A].tag
map.get(tag) match {
case Some((serviceLayer, scopedRef)) =>
scope.extend {
scopedRef
.set(serviceLayer.build.map(_.unsafe.get[A](tag)(Unsafe.unsafe)))
.foldZIO(
error => ZIO.fail(ServiceInitializationError(error)),
_ => ZIO.succeed(((), map))
)
}
case None =>
ZIO.fail(ServiceNotRegistered(tag))
}
}
}
}
/**
* Registers the specified service with a layer that constructs the service.
* Returns an implementation of the service that is backed by a `ScopedRef`
* which will handle reloading the service. Fails with a
* `ServiceInitializationError` exception if an error occurs while acquiring
* the service.
*/
def register[A: Tag: IsReloadable](
serviceLayer: ZLayer[Any, Any, A]
): ZIO[ServiceReloader, ServiceReloader.Error, A] =
ZIO.serviceWithZIO(_.register(serviceLayer))
/**
* Reloads the specified service, releasing any resources associated with the
* service and acquiring a new service. Fails with a
* `ServiceInitializationError` exception if an error occurs reloading the
* service or a `ServiceNotRegistered` exception if a layer constructing the
* service was never registered.
*/
def reload[A: Tag]: ZIO[ServiceReloader, ServiceReloader.Error, Unit] =
ZIO.serviceWithZIO(_.reload)
}
