Add Future support to JDK implementation

README.md

@@ -40,7 +40,7 @@ import java.time.Instant
 
 def updateData(): String = Instant.now.toString
 
-val data = AutoUpdatingVar.jdk(
+val data = AutoUpdatingVar.jdk( // or `AutoUpdatingVar.jdkFuture` if `updateData` returns a `scala.concurrent.Future`
   updateData(),
   // can also be dynamic based on the last data
   UpdateInterval.Static(1.second), 

periodic-core/src/main/scala/ca/dvgi/periodic/AutoUpdatingVar.scala

@@ -2,8 +2,7 @@ package ca.dvgi.periodic
 
 import scala.reflect.ClassTag
 import org.slf4j.LoggerFactory
-import ca.dvgi.periodic.jdk.Identity
-import ca.dvgi.periodic.jdk.JdkAutoUpdater
+import ca.dvgi.periodic.jdk._
 import scala.concurrent.duration.Duration
 import scala.concurrent.Future
 import java.util.concurrent.ScheduledExecutorService
@@ -122,7 +121,34 @@ object AutoUpdatingVar {
       executorOverride: Option[ScheduledExecutorService] = None
   )(implicit ct: ClassTag[T]): AutoUpdatingVar[Identity, Future, T] = {
     new AutoUpdatingVar(
-      new JdkAutoUpdater[T](blockUntilReadyTimeout, executorOverride)
+      new IdentityJdkAutoUpdater[T](blockUntilReadyTimeout, executorOverride)
+    )(
+      updateVar,
+      updateInterval,
+      updateAttemptStrategy,
+      handleInitializationError,
+      varNameOverride
+    )
+  }
+
+  /** An AutoUpdatingVar based on only the JDK, for use when `updateVar` returns a `Future`.
+    *
+    * @see
+    *   [[ca.dvgi.periodic.jdk.JdkAutoUpdater]]
+    * @see
+    *   [[ca.dvgi.periodic.AutoUpdatingVar]]
+    */
+  def jdkFuture[T](
+      updateVar: => Future[T],
+      updateInterval: UpdateInterval[T],
+      updateAttemptStrategy: UpdateAttemptStrategy,
+      handleInitializationError: PartialFunction[Throwable, Future[T]] = PartialFunction.empty,
+      varNameOverride: Option[String] = None,
+      blockUntilReadyTimeout: Option[Duration] = None,
+      executorOverride: Option[ScheduledExecutorService] = None
+  )(implicit ct: ClassTag[T]): AutoUpdatingVar[Future, Future, T] = {
+    new AutoUpdatingVar(
+      new FutureJdkAutoUpdater[T](blockUntilReadyTimeout, executorOverride)
     )(
       updateVar,
       updateInterval,

periodic-core/src/main/scala/ca/dvgi/periodic/jdk/FutureJdkAutoUpdater.scala

@@ -0,0 +1,13 @@
+package ca.dvgi.periodic.jdk
+
+import scala.concurrent.duration.Duration
+import java.util.concurrent.ScheduledExecutorService
+import scala.concurrent.Future
+import scala.concurrent.Await
+
+class FutureJdkAutoUpdater[T](
+    blockUntilReadyTimeout: Option[Duration] = None,
+    executorOverride: Option[ScheduledExecutorService] = None
+) extends JdkAutoUpdater[Future, T](blockUntilReadyTimeout, executorOverride) {
+  override protected def evalUpdate(ut: Future[T]): T = Await.result(ut, Duration.Inf)
+}

periodic-core/src/main/scala/ca/dvgi/periodic/jdk/IdentityJdkAutoUpdater.scala

@@ -0,0 +1,11 @@
+package ca.dvgi.periodic.jdk
+
+import scala.concurrent.duration.Duration
+import java.util.concurrent.ScheduledExecutorService
+
+class IdentityJdkAutoUpdater[T](
+    blockUntilReadyTimeout: Option[Duration] = None,
+    executorOverride: Option[ScheduledExecutorService] = None
+) extends JdkAutoUpdater[Identity, T](blockUntilReadyTimeout, executorOverride) {
+  override protected def evalUpdate(ut: Identity[T]): T = ut
+}

periodic-core/src/main/scala/ca/dvgi/periodic/jdk/JdkAutoUpdater.scala

@@ -26,10 +26,10 @@ import java.util.concurrent.ScheduledFuture
   * @param executorOverride
   *   If present, will be used instead of starting a new thread.
   */
-class JdkAutoUpdater[T](
-    blockUntilReadyTimeout: Option[Duration] = None,
-    executorOverride: Option[ScheduledExecutorService] = None
-) extends AutoUpdater[Identity, Future, T] {
+abstract class JdkAutoUpdater[U[T], T](
+    blockUntilReadyTimeout: Option[Duration],
+    executorOverride: Option[ScheduledExecutorService]
+) extends AutoUpdater[U, Future, T] {
 
   private val executor = executorOverride.getOrElse(Executors.newScheduledThreadPool(1))
 
@@ -45,10 +45,10 @@ class JdkAutoUpdater[T](
 
   override def start(
       log: Logger,
-      updateVar: () => T,
+      updateVar: () => U[T],
       updateInterval: UpdateInterval[T],
       updateAttemptStrategy: UpdateAttemptStrategy,
-      handleInitializationError: PartialFunction[Throwable, T]
+      handleInitializationError: PartialFunction[Throwable, U[T]]
   ): Future[Unit] = {
     executor.schedule(
       new Runnable {
@@ -57,13 +57,13 @@ class JdkAutoUpdater[T](
             Try(try {
               try {
                 log.info("Attempting initialization...")
-                updateVar()
+                evalUpdate(updateVar())
               } catch {
                 case NonFatal(e) =>
                   log.error("Failed to initialize var", e)
                   throw e
               }
-            } catch (handleInitializationError))
+            } catch (handleInitializationError.andThen(evalUpdate _)))
 
           tryV match {
             case Success(value) =>
@@ -108,9 +108,11 @@ class JdkAutoUpdater[T](
     ()
   }
 
+  protected def evalUpdate(ut: U[T]): T
+
   private def scheduleUpdate(nextUpdate: FiniteDuration)(implicit
       log: Logger,
-      updateVar: () => T,
+      updateVar: () => U[T],
       updateInterval: UpdateInterval[T],
       updateAttemptStrategy: UpdateAttemptStrategy
   ): Unit = {
@@ -131,14 +133,14 @@ class JdkAutoUpdater[T](
 
   private class UpdateVar(attempt: Int)(implicit
       log: Logger,
-      updateVar: () => T,
+      updateVar: () => U[T],
       updateInterval: UpdateInterval[T],
       updateAttemptStrategy: UpdateAttemptStrategy
   ) extends Runnable {
     def run(): Unit = {
       log.info("Attempting var update...")
       try {
-        val newV = updateVar()
+        val newV = evalUpdate(updateVar())
         variable = Some(newV)
         log.info("Successfully updated")
         scheduleUpdate(updateInterval.duration(newV))
@@ -159,7 +161,7 @@ class JdkAutoUpdater[T](
 
     private def reattempt(e: Throwable, delay: FiniteDuration)(implicit
         log: Logger,
-        updateVar: () => T,
+        updateVar: () => U[T],
         updateInterval: UpdateInterval[T],
         updateAttemptStrategy: UpdateAttemptStrategy
     ): Unit = {

periodic-core/src/test/scala/ca/dvgi/periodic/jdk/JdkAutoUpdaterTest.scala

@@ -31,7 +31,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
   FunFixture(
     _ => {
       val holder = new VarHolder
-      val v = new AutoUpdatingVar(new JdkAutoUpdater[Int](Some(5.seconds)))(
+      val v = new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int](Some(5.seconds)))(
         holder.get,
         UpdateInterval.Static(1.seconds),
         UpdateAttemptStrategy.Infinite(1.second)
@@ -66,7 +66,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
   FunFixture(
     _ => {
       val holder = new VarHolder
-      val v = new AutoUpdatingVar(new JdkAutoUpdater[Int](Some(1.second)))(
+      val v = new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int](Some(1.second)))(
         holder.get,
         UpdateInterval.Dynamic((i: Int) => i * 1.second),
         UpdateAttemptStrategy.Infinite(1.second)
@@ -98,7 +98,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
 
   FunFixture(
     _ => {
-      new AutoUpdatingVar(new JdkAutoUpdater[Int]())(
+      new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int]())(
         throw TestException,
         UpdateInterval.Static(1.seconds),
         UpdateAttemptStrategy.Infinite(1.second)
@@ -111,7 +111,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
 
   FunFixture(
     _ => {
-      new AutoUpdatingVar(new JdkAutoUpdater[Int]())(
+      new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int]())(
         {
           Thread.sleep(1000)
           1
@@ -129,7 +129,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
     "returns a failed future from constructor if the first update fails and instructed to block"
   ) {
     intercept[TestException.type] {
-      new AutoUpdatingVar(new JdkAutoUpdater[Int](Some(1.second)))(
+      new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int](Some(1.second)))(
         throw TestException,
         UpdateInterval.Static(1.seconds),
         UpdateAttemptStrategy.Infinite(1.second)
@@ -139,7 +139,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
 
   FunFixture(
     _ => {
-      new AutoUpdatingVar(new JdkAutoUpdater[Int](Some(1.second)))(
+      new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int](Some(1.second)))(
         throw TestException,
         UpdateInterval.Static(1.seconds),
         UpdateAttemptStrategy.Infinite(1.second),
@@ -159,7 +159,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
     _ => {
       val holder = new VarErrorHolder
       val v =
-        new AutoUpdatingVar(new JdkAutoUpdater[Int](Some(1.second)))(
+        new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int](Some(1.second)))(
           holder.get,
           UpdateInterval.Static(1.second),
           UpdateAttemptStrategy.Infinite(1.second),
@@ -190,7 +190,7 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
     _ => {
       val holder = new VarErrorHolder
       val v =
-        new AutoUpdatingVar(new JdkAutoUpdater[Int](Some(1.second)))(
+        new AutoUpdatingVar(new IdentityJdkAutoUpdater[Int](Some(1.second)))(
           holder.get,
           UpdateInterval.Static(1.second),
           UpdateAttemptStrategy
@@ -229,7 +229,9 @@ class JdkAutoUpdaterTest extends munit.FunSuite {
       val holder = new VarHolder
       val ses = Executors.newScheduledThreadPool(1)
       val v =
-        new AutoUpdatingVar(new JdkAutoUpdater[Int](Some(1.second), executorOverride = Some(ses)))(
+        new AutoUpdatingVar(
+          new IdentityJdkAutoUpdater[Int](Some(1.second), executorOverride = Some(ses))
+        )(
           holder.get,
           UpdateInterval.Static(2.seconds),
           UpdateAttemptStrategy.Infinite(1.second)