Extension function to convert a ListenableFuture to a CompletableFutu…

…re (#8)

* Added an extension function to convert a ListenableFuture to a CompletableFuture

* Using a bigger delay.

build.gradle

@@ -87,6 +87,6 @@ subprojects {
 }
 
 task wrapper(type: Wrapper) {
-    gradleVersion = "4.8.1"
+    gradleVersion = "3.5"
     distributionType = org.gradle.api.tasks.wrapper.Wrapper.DistributionType.ALL
 }

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,5 @@
-#Sun Aug 05 14:30:33 CDT 2018
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-3.5-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.8.1-all.zip

gradlew

@@ -33,11 +33,11 @@ DEFAULT_JVM_OPTS=""
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
 
-warn ( ) {
+warn () {
     echo "$*"
 }
 
-die ( ) {
+die () {
     echo
     echo "$*"
     echo
@@ -155,7 +155,7 @@ if $cygwin ; then
 fi
 
 # Escape application args
-save ( ) {
+save () {
     for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
     echo " "
 }

kotlin-futures-guava-to-jdk8/build.gradle

@@ -0,0 +1,3 @@
+dependencies {
+    compile project(":kotlin-futures-guava")
+}

kotlin-futures-guava-to-jdk8/src/main/kotlin/io/github/vjames19/futures/guava/ListenableFutureToCompletableFutureExt.kt

@@ -0,0 +1,19 @@
+package io.github.vjames19.futures.guava
+
+import com.google.common.util.concurrent.ListenableFuture
+import io.github.vjames19.futures.jdk8.DirectExecutor
+import io.github.vjames19.futures.jdk8.onComplete
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.Executor
+
+fun <T> ListenableFuture<T>.toCompletableFuture(executor: Executor = DirectExecutor): CompletableFuture<T> {
+    val future = CompletableFuture<T>()
+
+    onComplete(
+            executor = executor,
+            onFailure = { future.completeExceptionally(it) },
+            onSuccess = { future.complete(it)}
+    )
+
+    return future
+}

kotlin-futures-guava-to-jdk8/src/test/kotlin/io/github/vjames19/futures/guava/ListenableFutureToCompletableFutureSpec.kt

@@ -0,0 +1,39 @@
+package io.github.vjames19.futures.guava
+
+import io.github.vjames19.futures.jdk8.ImmediateFuture
+import io.github.vjames19.futures.jdk8.toListenableFuture
+import org.amshove.kluent.shouldEqualTo
+import org.amshove.kluent.shouldThrowTheException
+import org.amshove.kluent.withCause
+import org.jetbrains.spek.api.Spek
+import org.jetbrains.spek.api.dsl.describe
+import org.jetbrains.spek.api.dsl.given
+import org.jetbrains.spek.api.dsl.it
+import java.util.concurrent.ExecutionException
+
+
+object ListenableFutureToCompletableFutureSpec : Spek({
+
+    describe("toCompletableFuture") {
+        given("a successful future") {
+            it("it should be able to return a successful CompletableFuture") {
+                val listenableFuture = ImmediateFuture { 10 }
+                val future = listenableFuture.toCompletableFuture()
+
+                future.isDone shouldEqualTo true
+                future.isCompletedExceptionally shouldEqualTo false
+
+                future.get() shouldEqualTo 10
+            }
+        }
+
+        given("a failed future") {
+            it("should return the exception returned by the ListenableFuture") {
+                val listenableFuture = IllegalArgumentException().toListenableFuture<String>()
+                val future = listenableFuture.toCompletableFuture()
+
+                ({ future.get() }) shouldThrowTheException ExecutionException::class withCause IllegalArgumentException::class
+            }
+        }
+    }
+})

kotlin-futures-guava/src/main/kotlin/io/github/vjames19/futures/guava/ListenableFutureExt.kt

@@ -2,11 +2,10 @@ package io.github.vjames19.futures.jdk8
 
 import com.google.common.util.concurrent.*
 import java.util.*
-import java.util.concurrent.*
-import java.util.function.BiConsumer
-import java.util.function.BiFunction
-import java.util.function.Function
-import java.util.function.Supplier
+import java.util.concurrent.Callable
+import java.util.concurrent.Executor
+import java.util.concurrent.ExecutorService
+import java.util.concurrent.ForkJoinPool
 
 // Creation
 inline fun <A> Future(executor: ExecutorService = ForkJoinExecutor, crossinline block: () -> A): ListenableFuture<A> {
@@ -45,15 +44,21 @@ inline fun <A> ListenableFuture<A>.recover(crossinline f: (Throwable) -> A): Lis
         Futures.catching(this, Throwable::class.java) { f(it!!.cause ?: it) }
 
 inline fun <A> ListenableFuture<A>.recoverWith(executor: Executor = ForkJoinExecutor, crossinline f: (Throwable) -> ListenableFuture<A>): ListenableFuture<A> {
-    return Futures.catchingAsync(this, Throwable::class.java) { f(it!!.cause ?: it)}
+    return Futures.catchingAsync(
+            this,
+            Throwable::class.java,
+            AsyncFunction<Throwable, A> { throwable -> f(throwable!!.cause ?: throwable) },
+            executor
+    )
 }
 
+
 inline fun <A, reified E : Throwable> ListenableFuture<A>.mapError(crossinline f: (E) -> Throwable): ListenableFuture<A> {
     return Futures.catching(this, E::class.java) { throw f(it!!) }
 }
 
 inline fun <A> ListenableFuture<A>.fallbackTo(executor: Executor = ForkJoinExecutor, crossinline f: () -> ListenableFuture<A>): ListenableFuture<A> =
-        recoverWith(executor, { f() })
+        recoverWith(executor) { f() }
 
 
 // Callbacks
@@ -82,6 +87,7 @@ inline fun <A> ListenableFuture<A>.onSuccess(executor: Executor = ForkJoinExecut
 }
 
 inline fun <A> ListenableFuture<A>.onComplete(executor: Executor = ForkJoinExecutor, crossinline onFailure: (Throwable) -> Unit, crossinline onSuccess: (A) -> Unit): ListenableFuture<A> {
+
     Futures.addCallback(this, object : FutureCallback<A> {
         override fun onSuccess(result: A?) {
             onSuccess(result!!)

kotlin-futures-guava/src/test/kotlin/io/github/vjames19/futures/guava/ListenableFutureSpec.kt

@@ -1,13 +1,13 @@
-package io.github.vjames19.futures.jdk8
+package io.github.vjames19.futures.guava
 
 import com.google.common.util.concurrent.ListenableFuture
+import io.github.vjames19.futures.jdk8.*
 import org.amshove.kluent.*
 import org.jetbrains.spek.api.Spek
 import org.jetbrains.spek.api.dsl.describe
 import org.jetbrains.spek.api.dsl.given
 import org.jetbrains.spek.api.dsl.it
 import org.jetbrains.spek.api.dsl.on
-import java.util.concurrent.CompletableFuture
 
 /**
  * Created by victor.reventos on 7/1/17.

kotlin-futures-jdk8/src/test/kotlin/io/github/vjames19/futures/jdk8/FutureSpec.kt

@@ -213,9 +213,9 @@ object FutureSpec : Spek({
 
         given("a successful future") {
             it("should return the first completed") {
-                val f3 = Future { Thread.sleep(3000); 3 }
-                val f2 = Future { Thread.sleep(2000); 2 }
-                val f1 = Future { Thread.sleep(1); 1 }
+                val f3 = Future { Thread.sleep(30000); 3 }
+                val f2 = Future { Thread.sleep(20000); 2 }
+                val f1 = ImmediateFuture { 1 }
 
 
                 withFutures(listOf(f3, f2, f1)) {
@@ -229,9 +229,9 @@ object FutureSpec : Spek({
             given("that its the first to complete") {
                 it("should return it") {
 
-                    val f3 = Future { Thread.sleep(3000); 3 }
-                    val f2 = Future { Thread.sleep(2000); 2 }
-                    val f1 = Future<Int> { Thread.sleep(1); throw IllegalArgumentException() }
+                    val f3 = Future { Thread.sleep(30000); 3 }
+                    val f2 = Future { Thread.sleep(20000); 2 }
+                    val f1 = ImmediateFuture<Int> { throw IllegalArgumentException() }
                     withFutures(listOf(f3, f2, f1)) {
                         ({ Future.firstCompletedOf(it).get() }) shouldThrow AnyException
                     }
@@ -240,9 +240,9 @@ object FutureSpec : Spek({
 
             given("that its not the first one to complete") {
                 it("should return the first one") {
-                    val f3 = Future { Thread.sleep(3000); 3 }
-                    val f2 = Future<Int> { Thread.sleep(2000); throw IllegalArgumentException() }
-                    val f1 = Future { Thread.sleep(1); 1 }
+                    val f3 = Future { Thread.sleep(30000); 3 }
+                    val f2 = Future<Int> { Thread.sleep(20000); throw IllegalArgumentException() }
+                    val f1 = ImmediateFuture { 1 }
 
                     withFutures(listOf(f3, f2, f1)) {
                         Future.firstCompletedOf(listOf(f3, f2, f1)).get() shouldEqual 1

settings.gradle

@@ -18,4 +18,5 @@ include 'services:webservice'
 rootProject.name = 'kotlin-futures'
 
 include 'kotlin-futures-jdk8'
-include 'kotlin-futures-guava'
+include 'kotlin-futures-guava'
+include 'kotlin-futures-guava-to-jdk8'