Use WeakReference to allow garbage collection of Linkers

- Use mutable.Map instead of immutable as cache
com-lihaoyi · Nov 24, 2020 · 89b116a · 89b116a
1 parent cd86efd
commit 89b116a
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Showing 2 changed files with 29 additions and 21 deletions.
diff --git a/scalajslib/worker/0.6/src/ScalaJSWorkerImpl.scala b/scalajslib/worker/0.6/src/ScalaJSWorkerImpl.scala
@@ -9,24 +9,31 @@ import mill.scalajslib.api.{JsEnvConfig, ModuleKind}
 import org.scalajs.core.tools.io.IRFileCache.IRContainer
 import org.scalajs.core.tools.io._
 import org.scalajs.core.tools.jsdep.ResolvedJSDependency
-import org.scalajs.core.tools.linker.{Linker, ModuleInitializer, Semantics, StandardLinker, ModuleKind => ScalaJSModuleKind}
+import org.scalajs.core.tools.linker.{
+  Linker,
+  ModuleInitializer,
+  Semantics,
+  StandardLinker,
+  ModuleKind => ScalaJSModuleKind
+}
 import org.scalajs.core.tools.logging.ScalaConsoleLogger
 import org.scalajs.jsenv._
 import org.scalajs.testadapter.TestAdapter
 
+import scala.collection.mutable
+import scala.ref.WeakReference
+
 class ScalaJSWorkerImpl extends mill.scalajslib.api.ScalaJSWorkerApi {
   private case class LinkerInput(fullOpt: Boolean, moduleKind: ModuleKind, useECMAScript2015: Boolean)
   private object ScalaJSLinker {
-    private var cache = Map.empty[LinkerInput, Linker]
-    def reuseOrCreate(input: LinkerInput): Linker =
-      cache.getOrElse(
-        input,
-        {
-          val newLinker = createLinker(input)
-          cache += (input -> newLinker)
-          newLinker
-        }
-      )
+    private val cache = mutable.Map.empty[LinkerInput, WeakReference[Linker]]
+    def reuseOrCreate(input: LinkerInput): Linker = cache.get(input) match {
+      case Some(WeakReference(linker)) => linker
+      case _ =>
+        val newLinker = createLinker(input)
+        cache.update(input, WeakReference(newLinker))
+        newLinker
+    }
     private def createLinker(input: LinkerInput): Linker = {
       val semantics = input.fullOpt match {
         case true => Semantics.Defaults.optimized

diff --git a/scalajslib/worker/1/src/ScalaJSWorkerImpl.scala b/scalajslib/worker/1/src/ScalaJSWorkerImpl.scala
@@ -16,19 +16,20 @@ import org.scalajs.jsenv.nodejs.NodeJSEnv.SourceMap
 import org.scalajs.testing.adapter.TestAdapter
 import org.scalajs.testing.adapter.{TestAdapterInitializer => TAI}
 
+import scala.collection.mutable
+import scala.ref.WeakReference
+
 class ScalaJSWorkerImpl extends mill.scalajslib.api.ScalaJSWorkerApi {
   private case class LinkerInput(fullOpt: Boolean, moduleKind: ModuleKind, useECMAScript2015: Boolean)
   private object ScalaJSLinker {
-    private var cache = Map.empty[LinkerInput, Linker]
-    def reuseOrCreate(input: LinkerInput): Linker =
-      cache.getOrElse(
-        input,
-        {
-          val newLinker = createLinker(input)
-          cache += (input -> newLinker)
-          newLinker
-        }
-      )
+    private val cache = mutable.Map.empty[LinkerInput, WeakReference[Linker]]
+    def reuseOrCreate(input: LinkerInput): Linker = cache.get(input) match {
+      case Some(WeakReference(linker)) => linker
+      case _ =>
+        val newLinker = createLinker(input)
+        cache.update(input, WeakReference(newLinker))
+        newLinker
+    }
     private def createLinker(input: LinkerInput): Linker = {
       val semantics = input.fullOpt match {
           case true => Semantics.Defaults.optimized