From 2d2d2b6ce80298d7e229cc36ce555a7c9c94fed5 Mon Sep 17 00:00:00 2001
From: thomas <thomasjsvos@gmail.com>
Date: Thu, 8 Aug 2024 16:40:41 +0200
Subject: [PATCH] CMP-5906 Add option to enable Class data sharing (CDS)

---
 .../dsl/JvmApplicationDistributions.kt        |  2 ++
 .../internal/configureJvmApplication.kt       |  1 +
 .../application/tasks/AbstractJLinkTask.kt    | 29 +++++++++++++++++--
 .../README.md                                 | 15 ++++++++++
 4 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/dsl/JvmApplicationDistributions.kt b/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/dsl/JvmApplicationDistributions.kt
index f59b838b6a0..e063a8b39ed 100644
--- a/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/dsl/JvmApplicationDistributions.kt
+++ b/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/dsl/JvmApplicationDistributions.kt
@@ -19,6 +19,8 @@ abstract class JvmApplicationDistributions : AbstractDistributions() {
     }
     var includeAllModules: Boolean = false
 
+    var cds: Boolean = false
+
     val linux: LinuxPlatformSettings = objects.newInstance(LinuxPlatformSettings::class.java)
     open fun linux(fn: Action<LinuxPlatformSettings>) {
         fn.execute(linux)
diff --git a/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/internal/configureJvmApplication.kt b/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/internal/configureJvmApplication.kt
index 83d51089ef6..784bbde26ab 100644
--- a/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/internal/configureJvmApplication.kt
+++ b/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/internal/configureJvmApplication.kt
@@ -110,6 +110,7 @@ private fun JvmApplicationContext.configureCommonJvmDesktopTasks(): CommonJvmDes
         modules.set(provider { app.nativeDistributions.modules })
         includeAllModules.set(provider { app.nativeDistributions.includeAllModules })
         javaRuntimePropertiesFile.set(checkRuntime.flatMap { it.javaRuntimePropertiesFile })
+        cds.set(provider { app.nativeDistributions.cds })
         destinationDir.set(appTmpDir.dir("runtime"))
     }
 
diff --git a/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/tasks/AbstractJLinkTask.kt b/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/tasks/AbstractJLinkTask.kt
index b44237ef7b7..6dbb3be8b45 100644
--- a/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/tasks/AbstractJLinkTask.kt
+++ b/gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/tasks/AbstractJLinkTask.kt
@@ -11,8 +11,9 @@ import org.gradle.api.provider.Property
 import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.InputFile
 import org.gradle.api.tasks.Optional
-import org.jetbrains.compose.desktop.application.internal.RuntimeCompressionLevel
+import org.gradle.process.ExecResult
 import org.jetbrains.compose.desktop.application.internal.JvmRuntimeProperties
+import org.jetbrains.compose.desktop.application.internal.RuntimeCompressionLevel
 import org.jetbrains.compose.desktop.application.internal.cliArg
 import org.jetbrains.compose.internal.utils.ioFile
 import org.jetbrains.compose.internal.utils.notNullProperty
@@ -31,6 +32,9 @@ abstract class AbstractJLinkTask : AbstractJvmToolOperationTask("jlink") {
     @get:InputFile
     val javaRuntimePropertiesFile: RegularFileProperty = objects.fileProperty()
 
+    @get:Input
+    val cds: Property<Boolean> = objects.notNullProperty(false)
+
     @get:Input
     internal val stripDebug: Property<Boolean> = objects.notNullProperty(true)
 
@@ -56,12 +60,33 @@ abstract class AbstractJLinkTask : AbstractJvmToolOperationTask("jlink") {
             cliArg("--add-modules", m)
         }
 
+        val cds = cds.get()
+
+        if (cds) {
+            cliArg("--generate-cds-archive", true)
+        }
         cliArg("--strip-debug", stripDebug)
         cliArg("--no-header-files", noHeaderFiles)
         cliArg("--no-man-pages", noManPages)
-        cliArg("--strip-native-commands", stripNativeCommands)
+        // Native commands cannot be stripped if CDS is enabled, because bin/java is used by the
+        // CDS option. The files will be stripped later.
+        if (!cds) {
+            cliArg("--strip-native-commands", stripNativeCommands)
+        }
         cliArg("--compress", compressionLevel.orNull?.id)
 
         cliArg("--output", destinationDir)
     }
+
+    override fun checkResult(result: ExecResult) {
+        super.checkResult(result)
+        if (stripNativeCommands.get() && cds.get()) {
+            // Native files were not removed yet, so do it here.
+            destinationDir.get().dir("bin").asFile
+                .walkBottomUp()
+                // Windows JVM has its .ddl files in bin/
+                .filter { it.isFile && it.extension != "dll" }
+                .forEach { it.delete() }
+        }
+    }
 }
\ No newline at end of file
diff --git a/tutorials/Native_distributions_and_local_execution/README.md b/tutorials/Native_distributions_and_local_execution/README.md
index ffc91c4904d..e0fa7566b1a 100755
--- a/tutorials/Native_distributions_and_local_execution/README.md
+++ b/tutorials/Native_distributions_and_local_execution/README.md
@@ -280,6 +280,21 @@ compose.desktop {
 }
 ```
 
+## Enabling Class data sharing (CDS)
+
+This option requires JDK 18. Class data sharing (CDS) can be enabled which helps reduce the startup
+time and memory footprint.
+
+``` kotlin
+compose.desktop {
+    application {
+        nativeDistributions {
+            cds = true
+        }
+    }
+}
+```
+
 ## Packaging resources
 
 There are multiple ways to package and load resources with Compose for Desktop.