Use a private copy of QueueExecutionContext in `ExecutionContext.gl…

…obal`. This is required not to depend on the Scala.js library from `ExecutionContext`.
scala-js · sjrd · Jan 14, 2023 · Jan 14, 2023 · Jan 14, 2023 · Jan 14, 2023
commit c8fe6d05af1cbf3ad5eade58fa5bc35ae2e7c618
diff --git a/scalalib/overrides-2.12/scala/concurrent/ExecutionContext.scala b/scalalib/overrides-2.12/scala/concurrent/ExecutionContext.scala
@@ -75,7 +75,7 @@ trait ExecutionContext {
   /** Prepares for the execution of a task. Returns the prepared
      *  execution context. The recommended implementation of
      *  `prepare` is to return `this`.
-     * 
+     *
      *  This method should no longer be overridden or called. It was
      *  originally expected that `prepare` would be called by
      *  all libraries that consume ExecutionContexts, in order to
@@ -130,7 +130,7 @@ object ExecutionContext {
      * [[https://docs.oracle.com/javase/8/docs/api/java/lang/Runtime.html#availableProcessors-- available processors]].
      */
     implicit lazy val global: ExecutionContext =
-      scala.scalajs.concurrent.JSExecutionContext.queue
+      JSGlobalExecutionContext()
   }
 
   /** Creates an `ExecutionContext` from the given `ExecutorService`.
@@ -179,5 +179,3 @@ object ExecutionContext {
    */
   def defaultReporter: Throwable => Unit = _.printStackTrace()
 }
-
-
diff --git a/scalalib/overrides-2.13/scala/concurrent/ExecutionContext.scala b/scalalib/overrides-2.13/scala/concurrent/ExecutionContext.scala
@@ -140,7 +140,7 @@ object ExecutionContext {
    * @return the global `ExecutionContext`
    */
   final lazy val global: ExecutionContextExecutor =
-    scala.scalajs.concurrent.JSExecutionContext.queue
+    JSGlobalExecutionContext()
 
   /**
    * WARNING: Only ever execute logic which will quickly return control to the caller.

diff --git a/scalalib/overrides/scala/concurrent/JSGlobalExecutionContext.scala b/scalalib/overrides/scala/concurrent/JSGlobalExecutionContext.scala
@@ -0,0 +1,55 @@
+/*
+ * Scala.js (https://www.scala-js.org/)
+ *
+ * Copyright EPFL.
+ *
+ * Licensed under Apache License 2.0
+ * (https://www.apache.org/licenses/LICENSE-2.0).
+ *
+ * See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.
+ */
+
+package scala.concurrent
+
+import scala.scalajs.js
+import scala.scalajs.js.|
+
+private[concurrent] object JSGlobalExecutionContext {
+  def apply(): ExecutionContextExecutor =
+    if (js.typeOf(js.Dynamic.global.Promise) == "undefined") new TimeoutsExecutionContext
+    else new PromisesExecutionContext
+
+  private final class TimeoutsExecutionContext extends ExecutionContextExecutor {
+    def execute(runnable: Runnable): Unit = {
+      js.Dynamic.global.setTimeout({ () =>
+        try {
+          runnable.run()
+        } catch {
+          case t: Throwable => reportFailure(t)
+        }
+      }: js.Function0[Unit], 0)
+    }
+
+    def reportFailure(t: Throwable): Unit =
+      t.printStackTrace()
+  }
+
+  private final class PromisesExecutionContext extends ExecutionContextExecutor {
+    private val resolvedUnitPromise = js.Promise.resolve[Unit](())
+
+    def execute(runnable: Runnable): Unit = {
+      resolvedUnitPromise.`then` { (_: Unit) =>
+        try {
+          runnable.run()
+        } catch {
+          case t: Throwable => reportFailure(t)
+        }
+        (): Unit | js.Thenable[Unit]
+      }
+    }
+
+    def reportFailure(t: Throwable): Unit =
+      t.printStackTrace()
+  }
+}
diff --git a/test-suite/js/src/test/scala/org/scalajs/testsuite/jsinterop/AsyncTest.scala b/test-suite/js/src/test/scala/org/scalajs/testsuite/jsinterop/AsyncTest.scala
@@ -94,8 +94,6 @@ class AsyncTest {
       queueExecOrderTests { () =>
         tick(1)
       }(ExecutionContext.global)
-
-      assertSame(JSExecutionContext.queue, ExecutionContext.global)
     }
   }
-Original file line number
+Diff line change
@@ Expand Up / @@ -94,8 +94,6 @@ class AsyncTest { @@
           queueExecOrderTests { () =>
             tick(1)
           }(ExecutionContext.global)
-          assertSame(JSExecutionContext.queue, ExecutionContext.global)
         }
       }
@@ Expand Down @@