Merge pull request #7 from armanbilge/topic/port-polyfill

Polyfill copypasta

Author: djspiewak

build.sbt

@@ -111,7 +111,10 @@ lazy val root = project
 
 lazy val core = project
  .in(file("core"))
- .settings(name := "scala-js-macrotask-executor")
+ .settings(
+ name := "scala-js-macrotask-executor",
+ libraryDependencies += "org.scalameta" %%% "munit" % "0.7.29" % Test,
+ )
  .enablePlugins(ScalaJSPlugin)
 
 // this project solely exists for testing purposes
@@ -121,7 +124,10 @@ lazy val webworker = project
  .settings(
  name := "scala-js-macrotask-executor-webworker",
  scalaJSUseMainModuleInitializer := true,
- libraryDependencies += ("org.scala-js" %%% "scalajs-dom" % "1.2.0").cross(CrossVersion.for3Use2_13),
+ libraryDependencies ++= Seq(
+ ("org.scala-js" %%% "scalajs-dom" % "1.2.0").cross(CrossVersion.for3Use2_13),
+ "org.scalameta" %%% "munit" % "0.7.29" % Test,
+ ),
  (Test / test) := (Test / test).dependsOn(Compile / fastOptJS).value,
  buildInfoKeys := Seq[BuildInfoKey](scalaVersion, baseDirectory),
  buildInfoPackage := "org.scalajs")

core/src/main/scala/org/scalajs/macrotaskexecutor/MacrotaskExecutor.scala

@@ -16,9 +16,138 @@
 
 package org.scalajs.macrotaskexecutor
 
+import scala.collection.mutable
 import scala.concurrent.ExecutionContext
+import scala.scalajs.js
+import scala.util.Random
+import scala.util.control.NonFatal
 
+/**
+ * Based on https://github.com/YuzuJS/setImmediate
+ */
 object MacrotaskExecutor extends ExecutionContext {
- def execute(runnable: Runnable): Unit = ???
- def reportFailure(cause: Throwable): Unit = ???
+ private[this] val Undefined = "undefined"
+
+ def execute(runnable: Runnable): Unit =
+ setImmediate(() => runnable.run())
+
+ def reportFailure(cause: Throwable): Unit =
+ cause.printStackTrace()
+
+ private[this] val setImmediate: (() => Unit) => Unit = {
+ if (js.typeOf(js.Dynamic.global.setImmediate) == Undefined) {
+ var nextHandle = 1
+ val tasksByHandle = mutable.Map[Int, () => Unit]()
+ var currentlyRunningATask = false
+
+ def canUsePostMessage(): Boolean = {
+ // The test against `importScripts` prevents this implementation from being installed inside a web worker,
+ // where `global.postMessage` means something completely different and can't be used for this purpose.
+ if (js.typeOf(js.Dynamic.global.postMessage) != Undefined && js.typeOf(
+ js.Dynamic.global.importScripts) == Undefined) {
+ var postMessageIsAsynchronous = true
+ val oldOnMessage = js.Dynamic.global.onmessage
+
+ try {
+ // This line throws `ReferenceError: onmessage is not defined` in JSDOMNodeJS environment
+ js.Dynamic.global.onmessage = { () => postMessageIsAsynchronous = false }
+ js.Dynamic.global.postMessage("", "*")
+ js.Dynamic.global.onmessage = oldOnMessage
+ postMessageIsAsynchronous
+ } catch {
+ case NonFatal(_) =>
+ false
+ }
+ } else {
+ false
+ }
+ }
+
+ def runIfPresent(handle: Int): Unit = {
+ if (currentlyRunningATask) {
+ js.Dynamic.global.setTimeout(() => runIfPresent(handle), 0)
+ } else {
+ tasksByHandle.get(handle) match {
+ case Some(task) =>
+ currentlyRunningATask = true
+ try {
+ task()
+ } finally {
+ tasksByHandle -= handle
+ currentlyRunningATask = false
+ }
+
+ case None =>
+ }
+ }
+
+ ()
+ }
+
+ if (canUsePostMessage()) {
+ // postMessage is what we use for most modern browsers (when not in a webworker)
+
+ // generate a unique messagePrefix for everything we do
+ // collision here is *extremely* unlikely, but the random makes it somewhat less so
+ // as an example, if end-user code is using the setImmediate.js polyfill, we don't
+ // want to accidentally collide. Then again, if they *are* using the polyfill, we
+ // would pick it up above unless they init us first. Either way, the odds of
+ // collision here are microscopic.
+ val messagePrefix = "setImmediate$" + Random.nextInt() + "$"
+
+ def onGlobalMessage(event: js.Dynamic): Unit = {
+ if (/*event.source == js.Dynamic.global.global &&*/ js.typeOf(
+ event.data) == "string" && event
+ .data
+ .indexOf(messagePrefix)
+ .asInstanceOf[Int] == 0) {
+ runIfPresent(event.data.toString.substring(messagePrefix.length).toInt)
+ }
+ }
+
+ if (js.typeOf(js.Dynamic.global.addEventListener) != Undefined) {
+ js.Dynamic.global.addEventListener("message", onGlobalMessage _, false)
+ } else {
+ js.Dynamic.global.attachEvent("onmessage", onGlobalMessage _)
+ }
+
+ { k =>
+ val handle = nextHandle
+ nextHandle += 1
+
+ tasksByHandle += (handle -> k)
+ js.Dynamic.global.postMessage(messagePrefix + handle, "*")
+ ()
+ }
+ } else if (js.typeOf(js.Dynamic.global.MessageChannel) != Undefined) {
+ val channel = js.Dynamic.newInstance(js.Dynamic.global.MessageChannel)()
+
+ channel.port1.onmessage = { (event: js.Dynamic) =>
+ runIfPresent(event.data.asInstanceOf[Int])
+ }
+
+ { k =>
+ val handle = nextHandle
+ nextHandle += 1
+
+ tasksByHandle += (handle -> k)
+ channel.port2.postMessage(handle)
+ ()
+ }
+ } else {
+ // we don't try to look for process.nextTick since scalajs doesn't support old node
+ // we're also not going to bother fast-pathing for IE6; just fall through
+
+ { k =>
+ js.Dynamic.global.setTimeout(k, 0)
+ ()
+ }
+ }
+ } else {
+ { k =>
+ js.Dynamic.global.setImmediate(k)
+ ()
+ }
+ }
+ }
 }

core/src/test/scala/org/scalajs/macrotaskexecutor/MacrotaskExecutorSuite.scala

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2021 Scala.js (https://www.scala-js.org/)
+ *
+ * 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 org.scalajs.macrotaskexecutor
+
+import munit.FunSuite
+
+class MacrotaskExecutorSuite extends FunSuite {
+ 
+}

webworker/src/main/scala/org/scalajs/macrotaskexecutor/WebworkerSuiteRunner.scala

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2021 Scala.js (https://www.scala-js.org/)
+ *
+ * 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 org.scalajs.macrotaskexecutor
+
+object WebworkerSuiteRunner {
+ def main(args: Array[String]): Unit = ()
+}