From c4f6fd23df6a6c9a7334832bf5ceb7d892578307 Mon Sep 17 00:00:00 2001
From: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Mon, 18 Nov 2024 12:31:39 +0900
Subject: [PATCH 1/3] wip towards making jars with dylibs

This allows us to include dylibs in the jar and load them as resources.

This allows us to:

```
-> % java --enable-native-access=ALL-UNNAMED -cp
../../SwiftKit/build/classes/java/main:./build/libs/swift-and-java-jar-sample-lib-1.0-SNAPSHOT.jar
-Djava.library.path=/usr/lib/swift/ Example.java
[swift][MySwiftLibrary/MySwiftLibrary.swift:27](helloWorld())
helloWorld()
```

and we can even include the swiftCore libs in the jar to make it really
fat and include all swift dependencies. I think we should maybe make
that an option in the inevitable gradle plugin we'll need to do here.
---
 .../JExtractSwiftPlugin.swift                 |  10 +
 Samples/SwiftAndJavaJarSampleLib/Example.java |  23 ++
 .../SwiftAndJavaJarSampleLib/Package.swift    |  77 ++++++
 .../MySwiftLibrary/MySwiftLibrary.swift       | 101 +++++++
 .../Sources/MySwiftLibrary/swift-java.config  |   3 +
 Samples/SwiftAndJavaJarSampleLib/build.gradle | 180 +++++++++++++
 Samples/SwiftAndJavaJarSampleLib/gradlew      | 252 ++++++++++++++++++
 Samples/SwiftAndJavaJarSampleLib/gradlew.bat  |  94 +++++++
 .../swift/swiftkit/JavaToSwiftBenchmark.java  |  54 ++++
 .../com/example/swift/HelloJava2Swift.java    |  59 ++++
 .../com/example/swift/MySwiftClassTest.java   |  67 +++++
 .../com/example/swift/MySwiftLibraryTest.java |  65 +++++
 .../org/swift/swiftkit/MySwiftClassTest.java  |  39 +++
 .../org/swift/swiftkit/SwiftArenaTest.java    |  75 ++++++
 .../Swift2JavaTranslator+Printing.swift       |   6 +-
 .../java/org/swift/swiftkit/SwiftKit.java     |  93 +++++--
 .../swift/swiftkit/util/PlatformUtils.java    |  15 ++
 .../swift/swiftkit/gradle/BuildUtils.groovy   |  14 +-
 18 files changed, 1195 insertions(+), 32 deletions(-)
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/Example.java
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/Package.swift
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/MySwiftLibrary.swift
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/swift-java.config
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/build.gradle
 create mode 100755 Samples/SwiftAndJavaJarSampleLib/gradlew
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/gradlew.bat
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/src/main/java/com/example/swift/HelloJava2Swift.java
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftClassTest.java
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftLibraryTest.java
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/MySwiftClassTest.java
 create mode 100644 Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/SwiftArenaTest.java

diff --git a/Plugins/JExtractSwiftPlugin/JExtractSwiftPlugin.swift b/Plugins/JExtractSwiftPlugin/JExtractSwiftPlugin.swift
index f23a1dbf..94cd4aa6 100644
--- a/Plugins/JExtractSwiftPlugin/JExtractSwiftPlugin.swift
+++ b/Plugins/JExtractSwiftPlugin/JExtractSwiftPlugin.swift
@@ -23,6 +23,16 @@ struct JExtractSwiftBuildToolPlugin: BuildToolPlugin {
     // Note: Target doesn't have a directoryURL counterpart to directory,
     // so we cannot eliminate this deprecation warning.
     let sourceDir = target.directory.string
+    
+    let t = target.dependencies.first!
+    switch (t) {
+    case .target(let t):
+      t.sourceModule
+    case .product(let p):
+      p.sourceModules
+    @unknown default:
+      fatalError("Unknown target dependency type: \(t)")
+    }
 
     let toolURL = try context.tool(named: "JExtractSwiftTool").url
     let configuration = try readConfiguration(sourceDir: "\(sourceDir)")
diff --git a/Samples/SwiftAndJavaJarSampleLib/Example.java b/Samples/SwiftAndJavaJarSampleLib/Example.java
new file mode 100644
index 00000000..b5a2697b
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/Example.java
@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import com.example.swift.MySwiftLibrary;
+
+public class Example {
+
+    public static void main(String[] args) {
+        MySwiftLibrary.helloWorld();
+    }
+
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/Package.swift b/Samples/SwiftAndJavaJarSampleLib/Package.swift
new file mode 100644
index 00000000..5f132239
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/Package.swift
@@ -0,0 +1,77 @@
+// swift-tools-version: 6.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import CompilerPluginSupport
+import PackageDescription
+
+import class Foundation.FileManager
+import class Foundation.ProcessInfo
+
+// Note: the JAVA_HOME environment variable must be set to point to where
+// Java is installed, e.g.,
+//   Library/Java/JavaVirtualMachines/openjdk-21.jdk/Contents/Home.
+func findJavaHome() -> String {
+  if let home = ProcessInfo.processInfo.environment["JAVA_HOME"] {
+    return home
+  }
+
+  // This is a workaround for envs (some IDEs) which have trouble with
+  // picking up env variables during the build process
+  let path = "\(FileManager.default.homeDirectoryForCurrentUser.path()).java_home"
+  if let home = try? String(contentsOfFile: path, encoding: .utf8) {
+    if let lastChar = home.last, lastChar.isNewline {
+      return String(home.dropLast())
+    }
+
+    return home
+  }
+
+  fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
+}
+let javaHome = findJavaHome()
+
+let javaIncludePath = "\(javaHome)/include"
+#if os(Linux)
+  let javaPlatformIncludePath = "\(javaIncludePath)/linux"
+#elseif os(macOS)
+  let javaPlatformIncludePath = "\(javaIncludePath)/darwin"
+#else
+  // TODO: Handle windows as well
+  #error("Currently only macOS and Linux platforms are supported, this may change in the future.")
+#endif
+
+let package = Package(
+  name: "SwiftAndJavaJarSampleLib",
+  platforms: [
+    .macOS(.v10_15)
+  ],
+  products: [
+    .library(
+      name: "MySwiftLibrary",
+      type: .dynamic,
+      targets: ["MySwiftLibrary"]
+    ),
+
+  ],
+  dependencies: [
+    .package(name: "swift-java", path: "../../"),
+  ],
+  targets: [
+    .target(
+      name: "MySwiftLibrary",
+      dependencies: [
+        .product(name: "SwiftKitSwift", package: "swift-java"),
+      ],
+      exclude: [
+        "swift-java.config",
+      ],
+      swiftSettings: [
+        .swiftLanguageMode(.v5),
+        .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
+      ],
+      plugins: [
+        .plugin(name: "JExtractSwiftPlugin", package: "swift-java"),
+      ]
+    ),
+  ]
+)
diff --git a/Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/MySwiftLibrary.swift b/Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/MySwiftLibrary.swift
new file mode 100644
index 00000000..84e4618f
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/MySwiftLibrary.swift
@@ -0,0 +1,101 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+// This is a "plain Swift" file containing various types of declarations,
+// that is exported to Java by using the `jextract-swift` tool.
+//
+// No annotations are necessary on the Swift side to perform the export.
+
+#if os(Linux)
+import Glibc
+#else
+import Darwin.C
+#endif
+
+public func helloWorld() {
+  p("\(#function)")
+}
+
+public func globalTakeInt(i: Int) {
+  p("i:\(i)")
+}
+
+public func globalTakeIntInt(i: Int, j: Int) {
+  p("i:\(i), j:\(j)")
+}
+
+public func globalCallMeRunnable(run: () -> ()) {
+  run()
+}
+
+public class MySwiftClass {
+
+  public var len: Int
+  public var cap: Int
+
+  public init(len: Int, cap: Int) {
+    self.len = len
+    self.cap = cap
+
+    p("\(MySwiftClass.self).len = \(self.len)")
+    p("\(MySwiftClass.self).cap = \(self.cap)")
+    let addr = unsafeBitCast(self, to: UInt64.self)
+    p("initializer done, self = 0x\(String(addr, radix: 16, uppercase: true))")
+  }
+
+  deinit {
+    let addr = unsafeBitCast(self, to: UInt64.self)
+    p("Deinit, self = 0x\(String(addr, radix: 16, uppercase: true))")
+  }
+
+  public var counter: Int32 = 0
+
+  public func voidMethod() {
+    p("")
+  }
+
+  public func takeIntMethod(i: Int) {
+    p("i:\(i)")
+  }
+
+  public func echoIntMethod(i: Int) -> Int {
+    p("i:\(i)")
+    return i
+  }
+
+  public func makeIntMethod() -> Int {
+    p("make int -> 12")
+    return 12
+  }
+
+  public func makeRandomIntMethod() -> Int {
+    return Int.random(in: 1..<256)
+  }
+}
+
+// ==== Internal helpers
+
+private func p(_ msg: String, file: String = #fileID, line: UInt = #line, function: String = #function) {
+  print("[swift][\(file):\(line)](\(function)) \(msg)")
+  fflush(stdout)
+}
+
+#if os(Linux)
+// FIXME: why do we need this workaround?
+@_silgen_name("_objc_autoreleaseReturnValue")
+public func _objc_autoreleaseReturnValue(a: Any) {}
+
+@_silgen_name("objc_autoreleaseReturnValue")
+public func objc_autoreleaseReturnValue(a: Any) {}
+#endif
diff --git a/Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/swift-java.config b/Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/swift-java.config
new file mode 100644
index 00000000..6e5bc2af
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/Sources/MySwiftLibrary/swift-java.config
@@ -0,0 +1,3 @@
+{
+  "javaPackage": "com.example.swift"
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/build.gradle b/Samples/SwiftAndJavaJarSampleLib/build.gradle
new file mode 100644
index 00000000..a69cf2e2
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/build.gradle
@@ -0,0 +1,180 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+
+import groovy.json.JsonSlurper
+import org.swift.swiftkit.gradle.BuildUtils
+
+import java.nio.file.*
+
+plugins {
+    id("build-logic.java-library-conventions")
+    id "com.google.osdetector" version "1.7.3"
+    id("maven-publish")
+}
+
+group = "org.swift.swiftkit"
+version = "1.0-SNAPSHOT"
+
+def swiftBuildConfiguration() {
+    "release"
+}
+
+repositories {
+    mavenLocal()
+    mavenCentral()
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(22))
+    }
+}
+
+dependencies {
+    implementation(project(':SwiftKit'))
+
+    testImplementation(platform("org.junit:junit-bom:5.10.0"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+}
+
+// This is for development, when we edit the Swift swift-java project, the outputs of the generated sources may change.
+// Thus, we also need to watch and re-build the top level project.
+def compileSwiftJExtractPlugin = tasks.register("compileSwiftJExtractPlugin", Exec) {
+    description = "Rebuild the swift-java root project"
+
+    inputs.file(new File(rootDir, "Package.swift"))
+    inputs.dir(new File(rootDir, "Sources"))
+    outputs.dir(new File(rootDir, ".build"))
+
+    workingDir = rootDir
+    commandLine "swift"
+    args("build",
+            "-c", swiftBuildConfiguration(),
+            "--product", "SwiftKitSwift",
+            "--product", "JExtractSwiftPlugin",
+            "--product", "JExtractSwiftCommandPlugin")
+}
+
+def jextract = tasks.register("jextract", Exec) {
+    description = "Builds swift sources, including swift-java source generation"
+    dependsOn compileSwiftJExtractPlugin
+
+    // only because we depend on "live developing" the plugin while using this project to test it
+    inputs.file(new File(rootDir, "Package.swift"))
+    inputs.dir(new File(rootDir, "Sources"))
+
+    inputs.file(new File(projectDir, "Package.swift"))
+    inputs.dir(new File(projectDir, "Sources"))
+
+    // TODO: we can use package describe --type json to figure out which targets depend on JExtractSwiftPlugin and will produce outputs
+    //       Avoid adding this directory, but create the expected one specifically for all targets
+    //       which WILL produce sources because they have the plugin
+    outputs.dir(layout.buildDirectory.dir("../.build/plugins/outputs/${layout.projectDirectory.asFile.getName().toLowerCase()}"))
+
+    File baseSwiftPluginOutputsDir = layout.buildDirectory.dir("../.build/plugins/outputs/").get().asFile
+    if (!baseSwiftPluginOutputsDir.exists()) {
+        baseSwiftPluginOutputsDir.mkdirs()
+    }
+    Files.walk(layout.buildDirectory.dir("../.build/plugins/outputs/").get().asFile.toPath()).each {
+        // Add any Java sources generated by the plugin to our sourceSet
+        if (it.endsWith("JExtractSwiftPlugin/src/generated/java")) {
+            outputs.dir(it)
+        }
+    }
+
+    workingDir = layout.projectDirectory
+    commandLine "swift"
+    args("package", "jextract", "-v", "--log-level", "info") // TODO: pass log level from Gradle build
+}
+
+
+// Add the java-swift generated Java sources
+sourceSets {
+    main {
+        java {
+            srcDir(jextract)
+        }
+    }
+    test {
+        java {
+            srcDir(jextract)
+        }
+    }
+}
+
+tasks.build {
+    dependsOn("jextract")
+}
+
+tasks.named('test', Test) {
+    useJUnitPlatform()
+}
+
+
+// ==== Jar publishing
+
+List<String> swiftProductDylibPaths() {
+
+    def process = ['swift', 'package', 'describe', '--type', 'json'].execute()
+    process.waitFor()
+
+    if (process.exitValue() != 0) {
+        throw new RuntimeException("[swift describe] command failed with exit code: ${process.exitValue()}. Cannot find products! Output: ${process.err.text}")
+    }
+
+    def json = new JsonSlurper().parseText(process.text)
+
+    // TODO: require that we depend on swift-java
+    // TODO: all the products where the targets depend on swift-java plugin
+    def products =
+            json.targets.collect { target ->
+                target.product_memberships
+            }.flatten()
+
+
+    println("products = ${products}")
+    def productDylibPaths = products.collect {
+        "${layout.projectDirectory}/.build/${swiftBuildConfiguration()}/lib${it}.dylib"
+    }
+    println("PRODUCT DYLIB PATHS = ${productDylibPaths}")
+
+    return productDylibPaths
+}
+
+processResources {
+    dependsOn "jextract"
+
+    def dylibs = [
+        "${layout.projectDirectory}/.build/${swiftBuildConfiguration()}/libSwiftKitSwift.dylib"
+    ]
+    dylibs.addAll(swiftProductDylibPaths())
+    from(dylibs)
+}
+
+base {
+    archivesName = "swift-and-java-jar-sample-lib"
+}
+
+publishing {
+    publications {
+        maven(MavenPublication) {
+            artifactId = "swift-and-java-jar-sample-lib"
+            from components.java
+        }
+    }
+    repositories {
+        mavenLocal()
+    }
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/gradlew b/Samples/SwiftAndJavaJarSampleLib/gradlew
new file mode 100755
index 00000000..f5feea6d
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/gradlew
@@ -0,0 +1,252 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s
+' "$PWD" ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/Samples/SwiftAndJavaJarSampleLib/gradlew.bat b/Samples/SwiftAndJavaJarSampleLib/gradlew.bat
new file mode 100644
index 00000000..9b42019c
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/gradlew.bat
@@ -0,0 +1,94 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java b/Samples/SwiftAndJavaJarSampleLib/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java
new file mode 100644
index 00000000..614697a3
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java
@@ -0,0 +1,54 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit;
+
+import java.util.concurrent.TimeUnit;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.infra.Blackhole;
+
+import com.example.swift.MySwiftClass;
+
+@SuppressWarnings("unused")
+public class JavaToSwiftBenchmark {
+
+    @State(Scope.Benchmark)
+    public static class BenchmarkState {
+        MySwiftClass obj;
+
+        @Setup(Level.Trial)
+        public void beforeALl() {
+            System.loadLibrary("swiftCore");
+            System.loadLibrary("ExampleSwiftLibrary");
+
+            // Tune down debug statements so they don't fill up stdout
+            System.setProperty("jextract.trace.downcalls", "false");
+
+            obj = new MySwiftClass(1, 2);
+        }
+    }
+
+    @Benchmark @BenchmarkMode(Mode.AverageTime) @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public void simpleSwiftApiCall(BenchmarkState state, Blackhole blackhole) {
+        blackhole.consume(state.obj.makeRandomIntMethod());
+    }
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/main/java/com/example/swift/HelloJava2Swift.java b/Samples/SwiftAndJavaJarSampleLib/src/main/java/com/example/swift/HelloJava2Swift.java
new file mode 100644
index 00000000..2a86e403
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/src/main/java/com/example/swift/HelloJava2Swift.java
@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package com.example.swift;
+
+// Import swift-extract generated sources
+
+import com.example.swift.MySwiftLibrary;
+import com.example.swift.MySwiftClass;
+
+// Import javakit/swiftkit support libraries
+import org.swift.swiftkit.SwiftArena;
+import org.swift.swiftkit.SwiftKit;
+import org.swift.swiftkit.SwiftValueWitnessTable;
+
+import java.util.Arrays;
+
+public class HelloJava2Swift {
+
+    public static void main(String[] args) {
+        boolean traceDowncalls = Boolean.getBoolean("jextract.trace.downcalls");
+        System.out.println("Property: jextract.trace.downcalls = " + traceDowncalls);
+
+        System.out.print("Property: java.library.path = " +SwiftKit.getJavaLibraryPath());
+
+        examples();
+    }
+
+    static void examples() {
+        MySwiftLibrary.helloWorld();
+
+        MySwiftLibrary.globalTakeInt(1337);
+
+        // Example of using an arena; MyClass.deinit is run at end of scope
+        try (var arena = SwiftArena.ofConfined()) {
+            MySwiftClass obj = new MySwiftClass(arena, 2222, 7777);
+
+            // just checking retains/releases work
+            SwiftKit.retain(obj.$memorySegment());
+            SwiftKit.release(obj.$memorySegment());
+
+            obj.voidMethod();
+            obj.takeIntMethod(42);
+        }
+
+        System.out.println("DONE.");
+    }
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftClassTest.java b/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftClassTest.java
new file mode 100644
index 00000000..fa17ef1a
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftClassTest.java
@@ -0,0 +1,67 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package com.example.swift;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.swift.swiftkit.SwiftKit;
+
+import java.io.File;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class MySwiftClassTest {
+
+    void checkPaths(Throwable throwable) {
+        var paths = SwiftKit.getJavaLibraryPath().split(":");
+        for (var path : paths) {
+            System.out.println("CHECKING PATH: " + path);
+            Stream.of(new File(path).listFiles())
+                    .filter(file -> !file.isDirectory())
+                    .forEach((file) -> {
+                        System.out.println("  - " + file.getPath());
+                    });
+        }
+
+        throw new RuntimeException(throwable);
+    }
+
+    @Test
+    void test_MySwiftClass_voidMethod() {
+        try {
+            MySwiftClass o = new MySwiftClass(12, 42);
+            o.voidMethod();
+        } catch (Throwable throwable) {
+            checkPaths(throwable);
+        }
+    }
+
+    @Test
+    void test_MySwiftClass_makeIntMethod() {
+        MySwiftClass o = new MySwiftClass(12, 42);
+        var got = o.makeIntMethod();
+        assertEquals(12, got);
+    }
+
+    @Test
+    @Disabled // TODO: Need var mangled names in interfaces
+    void test_MySwiftClass_property_len() {
+        MySwiftClass o = new MySwiftClass(12, 42);
+        var got = o.getLen();
+        assertEquals(12, got);
+    }
+
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftLibraryTest.java b/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftLibraryTest.java
new file mode 100644
index 00000000..ffa90359
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftLibraryTest.java
@@ -0,0 +1,65 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package com.example.swift;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.swift.swiftkit.SwiftKit;
+
+import java.util.Arrays;
+import java.util.concurrent.CountDownLatch;
+import java.util.stream.Collectors;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class MySwiftLibraryTest {
+
+    @Test
+    void call_helloWorld() {
+        MySwiftLibrary.helloWorld();
+
+        assertNotNull(MySwiftLibrary.helloWorld$address());
+    }
+
+    @Test
+    void call_globalTakeInt() {
+        MySwiftLibrary.globalTakeInt(12);
+
+        assertNotNull(MySwiftLibrary.globalTakeInt$address());
+    }
+
+    @Test
+    @Disabled("Upcalls not yet implemented in new scheme")
+    @SuppressWarnings({"Convert2Lambda", "Convert2MethodRef"})
+    void call_globalCallMeRunnable() {
+        CountDownLatch countDownLatch = new CountDownLatch(3);
+
+        MySwiftLibrary.globalCallMeRunnable(new Runnable() {
+            @Override
+            public void run() {
+                countDownLatch.countDown();
+            }
+        });
+        assertEquals(2, countDownLatch.getCount());
+
+        MySwiftLibrary.globalCallMeRunnable(() -> countDownLatch.countDown());
+        assertEquals(1, countDownLatch.getCount());
+
+        MySwiftLibrary.globalCallMeRunnable(countDownLatch::countDown);
+        assertEquals(0, countDownLatch.getCount());
+    }
+
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/MySwiftClassTest.java b/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/MySwiftClassTest.java
new file mode 100644
index 00000000..633d5f1c
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/MySwiftClassTest.java
@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+import com.example.swift.MySwiftClass;
+
+public class MySwiftClassTest {
+
+    @Test
+    void call_retain_retainCount_release() {
+        var arena = SwiftArena.ofConfined();
+        var obj = new MySwiftClass(arena, 1, 2);
+
+        assertEquals(1, SwiftKit.retainCount(obj.$memorySegment()));
+        // TODO: test directly on SwiftHeapObject inheriting obj
+
+        SwiftKit.retain(obj.$memorySegment());
+        assertEquals(2, SwiftKit.retainCount(obj.$memorySegment()));
+
+        SwiftKit.release(obj.$memorySegment());
+        assertEquals(1, SwiftKit.retainCount(obj.$memorySegment()));
+    }
+}
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/SwiftArenaTest.java b/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/SwiftArenaTest.java
new file mode 100644
index 00000000..ad514e1b
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/SwiftArenaTest.java
@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit;
+
+import com.example.swift.MySwiftClass;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.DisabledIf;
+import org.swift.swiftkit.util.PlatformUtils;
+
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.swift.swiftkit.SwiftKit.*;
+import static org.swift.swiftkit.SwiftKit.retainCount;
+
+public class SwiftArenaTest {
+
+    static boolean isAmd64() {
+        return PlatformUtils.isAmd64();
+    }
+
+    // FIXME: The destroy witness table call hangs on x86_64 platforms during the destroy witness table call
+    //        See: https://github.com/swiftlang/swift-java/issues/97
+    @Test
+    @DisabledIf("isAmd64")
+    public void arena_releaseClassOnClose_class_ok() {
+        try (var arena = SwiftArena.ofConfined()) {
+            var obj = new MySwiftClass(arena,1, 2);
+
+            retain(obj.$memorySegment());
+            assertEquals(2, retainCount(obj.$memorySegment()));
+
+            release(obj.$memorySegment());
+            assertEquals(1, retainCount(obj.$memorySegment()));
+        }
+
+        // TODO: should we zero out the $memorySegment perhaps?
+    }
+
+    @Test
+    public void arena_releaseClassOnClose_class_leaked() {
+        String memorySegmentDescription = "<none>";
+
+        try {
+            try (var arena = SwiftArena.ofConfined()) {
+                var obj = new MySwiftClass(arena,1, 2);
+                memorySegmentDescription = obj.$memorySegment().toString();
+
+                // Pretend that we "leaked" the class, something still holds a reference to it while we try to destroy it
+                retain(obj.$memorySegment());
+                assertEquals(2, retainCount(obj.$memorySegment()));
+            }
+
+            fail("Expected exception to be thrown while the arena is closed!");
+        } catch (Exception ex) {
+            // The message should point out which objects "leaked":
+            assertTrue(ex.getMessage().contains(memorySegmentDescription));
+        }
+
+    }
+}
diff --git a/Sources/JExtractSwift/Swift2JavaTranslator+Printing.swift b/Sources/JExtractSwift/Swift2JavaTranslator+Printing.swift
index cb9fd7ed..5a367840 100644
--- a/Sources/JExtractSwift/Swift2JavaTranslator+Printing.swift
+++ b/Sources/JExtractSwift/Swift2JavaTranslator+Printing.swift
@@ -325,9 +325,9 @@ extension Swift2JavaTranslator {
         static final SymbolLookup SYMBOL_LOOKUP = getSymbolLookup();
         private static SymbolLookup getSymbolLookup() {
             // Ensure Swift and our Lib are loaded during static initialization of the class.
-            System.loadLibrary("swiftCore");
-            System.loadLibrary("SwiftKitSwift");
-            System.loadLibrary(LIB_NAME);
+            SwiftKit.loadLibrary("swiftCore");
+            SwiftKit.loadLibrary("SwiftKitSwift");
+            SwiftKit.loadLibrary(LIB_NAME);
 
             if (PlatformUtils.isMacOS()) {
                 return SymbolLookup.libraryLookup(System.mapLibraryName(LIB_NAME), LIBRARY_ARENA)
diff --git a/SwiftKit/src/main/java/org/swift/swiftkit/SwiftKit.java b/SwiftKit/src/main/java/org/swift/swiftkit/SwiftKit.java
index 1951c23e..858f5500 100644
--- a/SwiftKit/src/main/java/org/swift/swiftkit/SwiftKit.java
+++ b/SwiftKit/src/main/java/org/swift/swiftkit/SwiftKit.java
@@ -16,8 +16,14 @@
 
 import org.swift.swiftkit.util.PlatformUtils;
 
+import java.io.File;
+import java.io.IOException;
 import java.lang.foreign.*;
 import java.lang.invoke.MethodHandle;
+import java.nio.file.CopyOption;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
 import java.util.Arrays;
 import java.util.Optional;
 import java.util.stream.Collectors;
@@ -63,31 +69,31 @@ private static SymbolLookup getSymbolLookup() {
     public SwiftKit() {
     }
 
-  public static void traceDowncall(Object... args) {
-      var ex = new RuntimeException();
-
-      String traceArgs = Arrays.stream(args)
-              .map(Object::toString)
-              .collect(Collectors.joining(", "));
-      System.out.printf("[java][%s:%d] Downcall: %s(%s)\n",
-              ex.getStackTrace()[1].getFileName(),
-              ex.getStackTrace()[1].getLineNumber(),
-              ex.getStackTrace()[1].getMethodName(),
-              traceArgs);
-  }
-
-  public static void trace(Object... args) {
-      var ex = new RuntimeException();
-
-      String traceArgs = Arrays.stream(args)
-              .map(Object::toString)
-              .collect(Collectors.joining(", "));
-      System.out.printf("[java][%s:%d] %s: %s\n",
-              ex.getStackTrace()[1].getFileName(),
-              ex.getStackTrace()[1].getLineNumber(),
-              ex.getStackTrace()[1].getMethodName(),
-              traceArgs);
-  }
+    public static void traceDowncall(Object... args) {
+        var ex = new RuntimeException();
+
+        String traceArgs = Arrays.stream(args)
+                .map(Object::toString)
+                .collect(Collectors.joining(", "));
+        System.out.printf("[java][%s:%d] Downcall: %s(%s)\n",
+                ex.getStackTrace()[1].getFileName(),
+                ex.getStackTrace()[1].getLineNumber(),
+                ex.getStackTrace()[1].getMethodName(),
+                traceArgs);
+    }
+
+    public static void trace(Object... args) {
+        var ex = new RuntimeException();
+
+        String traceArgs = Arrays.stream(args)
+                .map(Object::toString)
+                .collect(Collectors.joining(", "));
+        System.out.printf("[java][%s:%d] %s: %s\n",
+                ex.getStackTrace()[1].getFileName(),
+                ex.getStackTrace()[1].getLineNumber(),
+                ex.getStackTrace()[1].getMethodName(),
+                traceArgs);
+    }
 
     static MemorySegment findOrThrow(String symbol) {
         return SYMBOL_LOOKUP.find(symbol)
@@ -102,6 +108,42 @@ public static boolean getJextractTraceDowncalls() {
         return Boolean.getBoolean("jextract.trace.downcalls");
     }
 
+    // ==== ------------------------------------------------------------------------------------------------------------
+    // Loading libraries
+
+    public static void loadLibrary(String libname) {
+        // TODO: avoid concurrent loadResource calls; one load is enough esp since we cause File IO when we do that
+        try {
+            // try to load a dylib from our classpath, e.g. when we included it in our jar
+            loadResourceLibrary(libname);
+        } catch (UnsatisfiedLinkError | RuntimeException e) {
+            // fallback to plain system path loading
+            System.loadLibrary(libname);
+        }
+    }
+
+    public static void loadResourceLibrary(String libname) {
+        var resourceName = PlatformUtils.dynamicLibraryName(libname);
+        if (SwiftKit.TRACE_DOWNCALLS) {
+            System.out.println("[swift-java] Loading resource library: " + resourceName);
+        }
+
+        try (var libInputStream = SwiftKit.class.getResourceAsStream("/" + resourceName)) {
+            if (libInputStream == null) {
+                throw new RuntimeException("Expected library '" + libname + "' ('" + resourceName + "') was not found as resource!");
+            }
+
+            // TODO: we could do an in memory file system here
+            var tempFile = File.createTempFile(libname, "");
+            tempFile.deleteOnExit();
+            Files.copy(libInputStream, tempFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
+
+            System.load(tempFile.getAbsolutePath());
+        } catch (IOException e) {
+            throw new RuntimeException("Failed to load dynamic library '" + libname + "' ('" + resourceName + "') as resource!", e);
+        }
+    }
+
     // ==== ------------------------------------------------------------------------------------------------------------
     // free
 
@@ -396,7 +438,6 @@ public static long getSwiftInt(MemorySegment memorySegment, long offset) {
     }
 
 
-
     private static class swift_getTypeName {
 
         /**
diff --git a/SwiftKit/src/main/java/org/swift/swiftkit/util/PlatformUtils.java b/SwiftKit/src/main/java/org/swift/swiftkit/util/PlatformUtils.java
index 2c51143f..6addb31d 100644
--- a/SwiftKit/src/main/java/org/swift/swiftkit/util/PlatformUtils.java
+++ b/SwiftKit/src/main/java/org/swift/swiftkit/util/PlatformUtils.java
@@ -35,4 +35,19 @@ public static boolean isAmd64() {
         String arch = System.getProperty("os.arch");
         return arch.equals("amd64") || arch.equals("x86_64");
     }
+
+    public static String dynamicLibraryName(String base) {
+        if (isLinux()) {
+            return "lib" + uppercaseFistLetter(base) + ".so";
+        } else {
+            return "lib" + uppercaseFistLetter(base) + ".dylib";
+        }
+    }
+
+    static String uppercaseFistLetter(String base) {
+        if (base == null || base.isEmpty()) {
+            return base;
+        }
+        return base.substring(0, 1).toUpperCase() + base.substring(1);
+    }
 }
diff --git a/buildSrc/src/main/groovy/org/swift/swiftkit/gradle/BuildUtils.groovy b/buildSrc/src/main/groovy/org/swift/swiftkit/gradle/BuildUtils.groovy
index 4fcddbee..678f6461 100644
--- a/buildSrc/src/main/groovy/org/swift/swiftkit/gradle/BuildUtils.groovy
+++ b/buildSrc/src/main/groovy/org/swift/swiftkit/gradle/BuildUtils.groovy
@@ -16,6 +16,15 @@ package org.swift.swiftkit.gradle
 
 final class BuildUtils {
 
+    static String swiftCoreDylibPath() {
+        def osName = System.getProperty("os.name")
+        def isLinux = osName.toLowerCase(Locale.getDefault()).contains("linux")
+
+        return isLinux ?
+                "/usr/lib/swift/linux" :
+                "/usr/lib/swift"
+    }
+
     /// Find library paths for 'java.library.path' when running or testing projects inside this build.
     static def javaLibraryPaths(File rootDir) {
         def osName = System.getProperty("os.name")
@@ -44,13 +53,12 @@ final class BuildUtils {
                 // system paths
                 isLinux ?
                         [
-                                "/usr/lib/swift/linux",
+                                swiftCoreDylibPath(),
                                 // TODO: should we be Swiftly aware and then use the currently used path?
                                 System.getProperty("user.home") + "/.local/share/swiftly/toolchains/6.0.2/usr/lib/swift/linux"
                         ] :
                         [
-                                // assume macOS
-                                "/usr/lib/swift/"
+                                swiftCoreDylibPath(),
                         ]
 
         return releasePaths + debugPaths + systemPaths

From d797f5c40614cf09b3cb2cf50a45896b30b2d210 Mon Sep 17 00:00:00 2001
From: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Mon, 18 Nov 2024 13:32:23 +0900
Subject: [PATCH 2/3] platform specific jar name
 ...-1.0-SNAPSHOT-osx-aarch_64.jar

---
 Samples/SwiftAndJavaJarSampleLib/build.gradle | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Samples/SwiftAndJavaJarSampleLib/build.gradle b/Samples/SwiftAndJavaJarSampleLib/build.gradle
index a69cf2e2..2125011d 100644
--- a/Samples/SwiftAndJavaJarSampleLib/build.gradle
+++ b/Samples/SwiftAndJavaJarSampleLib/build.gradle
@@ -144,11 +144,11 @@ List<String> swiftProductDylibPaths() {
             }.flatten()
 
 
-    println("products = ${products}")
+
     def productDylibPaths = products.collect {
+        logger.info("[swift-java] Include Swift product: '${it}' in product resource paths.")
         "${layout.projectDirectory}/.build/${swiftBuildConfiguration()}/lib${it}.dylib"
     }
-    println("PRODUCT DYLIB PATHS = ${productDylibPaths}")
 
     return productDylibPaths
 }
@@ -163,6 +163,10 @@ processResources {
     from(dylibs)
 }
 
+jar {
+    archiveClassifier = osdetector.classifier
+}
+
 base {
     archivesName = "swift-and-java-jar-sample-lib"
 }

From a73c9a016138dc9eb2d5f076b24cc0d9983e5d6b Mon Sep 17 00:00:00 2001
From: Konrad `ktoso` Malawski <konrad_malawski@apple.com>
Date: Mon, 18 Nov 2024 17:55:47 +0900
Subject: [PATCH 3/3] sample gradlew files must be symlinks

---
 Samples/SwiftAndJavaJarSampleLib/gradlew     | 253 +------------------
 Samples/SwiftAndJavaJarSampleLib/gradlew.bat |  95 +------
 2 files changed, 2 insertions(+), 346 deletions(-)
 mode change 100755 => 120000 Samples/SwiftAndJavaJarSampleLib/gradlew
 mode change 100644 => 120000 Samples/SwiftAndJavaJarSampleLib/gradlew.bat

diff --git a/Samples/SwiftAndJavaJarSampleLib/gradlew b/Samples/SwiftAndJavaJarSampleLib/gradlew
deleted file mode 100755
index f5feea6d..00000000
--- a/Samples/SwiftAndJavaJarSampleLib/gradlew
+++ /dev/null
@@ -1,252 +0,0 @@
-#!/bin/sh
-
-#
-# Copyright © 2015-2021 the original authors.
-#
-# 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
-#
-#      https://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.
-#
-# SPDX-License-Identifier: Apache-2.0
-#
-
-##############################################################################
-#
-#   Gradle start up script for POSIX generated by Gradle.
-#
-#   Important for running:
-#
-#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
-#       noncompliant, but you have some other compliant shell such as ksh or
-#       bash, then to run this script, type that shell name before the whole
-#       command line, like:
-#
-#           ksh Gradle
-#
-#       Busybox and similar reduced shells will NOT work, because this script
-#       requires all of these POSIX shell features:
-#         * functions;
-#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
-#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
-#         * compound commands having a testable exit status, especially «case»;
-#         * various built-in commands including «command», «set», and «ulimit».
-#
-#   Important for patching:
-#
-#   (2) This script targets any POSIX shell, so it avoids extensions provided
-#       by Bash, Ksh, etc; in particular arrays are avoided.
-#
-#       The "traditional" practice of packing multiple parameters into a
-#       space-separated string is a well documented source of bugs and security
-#       problems, so this is (mostly) avoided, by progressively accumulating
-#       options in "$@", and eventually passing that to Java.
-#
-#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
-#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
-#       see the in-line comments for details.
-#
-#       There are tweaks for specific operating systems such as AIX, CygWin,
-#       Darwin, MinGW, and NonStop.
-#
-#   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
-#       within the Gradle project.
-#
-#       You can find Gradle at https://github.com/gradle/gradle/.
-#
-##############################################################################
-
-# Attempt to set APP_HOME
-
-# Resolve links: $0 may be a link
-app_path=$0
-
-# Need this for daisy-chained symlinks.
-while
-    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
-    [ -h "$app_path" ]
-do
-    ls=$( ls -ld "$app_path" )
-    link=${ls#*' -> '}
-    case $link in             #(
-      /*)   app_path=$link ;; #(
-      *)    app_path=$APP_HOME$link ;;
-    esac
-done
-
-# This is normally unused
-# shellcheck disable=SC2034
-APP_BASE_NAME=${0##*/}
-# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
-APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s
-' "$PWD" ) || exit
-
-# Use the maximum available, or set MAX_FD != -1 to use that value.
-MAX_FD=maximum
-
-warn () {
-    echo "$*"
-} >&2
-
-die () {
-    echo
-    echo "$*"
-    echo
-    exit 1
-} >&2
-
-# OS specific support (must be 'true' or 'false').
-cygwin=false
-msys=false
-darwin=false
-nonstop=false
-case "$( uname )" in                #(
-  CYGWIN* )         cygwin=true  ;; #(
-  Darwin* )         darwin=true  ;; #(
-  MSYS* | MINGW* )  msys=true    ;; #(
-  NONSTOP* )        nonstop=true ;;
-esac
-
-CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
-
-
-# Determine the Java command to use to start the JVM.
-if [ -n "$JAVA_HOME" ] ; then
-    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
-        # IBM's JDK on AIX uses strange locations for the executables
-        JAVACMD=$JAVA_HOME/jre/sh/java
-    else
-        JAVACMD=$JAVA_HOME/bin/java
-    fi
-    if [ ! -x "$JAVACMD" ] ; then
-        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
-
-Please set the JAVA_HOME variable in your environment to match the
-location of your Java installation."
-    fi
-else
-    JAVACMD=java
-    if ! command -v java >/dev/null 2>&1
-    then
-        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-
-Please set the JAVA_HOME variable in your environment to match the
-location of your Java installation."
-    fi
-fi
-
-# Increase the maximum file descriptors if we can.
-if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
-    case $MAX_FD in #(
-      max*)
-        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC2039,SC3045
-        MAX_FD=$( ulimit -H -n ) ||
-            warn "Could not query maximum file descriptor limit"
-    esac
-    case $MAX_FD in  #(
-      '' | soft) :;; #(
-      *)
-        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC2039,SC3045
-        ulimit -n "$MAX_FD" ||
-            warn "Could not set maximum file descriptor limit to $MAX_FD"
-    esac
-fi
-
-# Collect all arguments for the java command, stacking in reverse order:
-#   * args from the command line
-#   * the main class name
-#   * -classpath
-#   * -D...appname settings
-#   * --module-path (only if needed)
-#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
-
-# For Cygwin or MSYS, switch paths to Windows format before running java
-if "$cygwin" || "$msys" ; then
-    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
-    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
-
-    JAVACMD=$( cygpath --unix "$JAVACMD" )
-
-    # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    for arg do
-        if
-            case $arg in                                #(
-              -*)   false ;;                            # don't mess with options #(
-              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
-                    [ -e "$t" ] ;;                      #(
-              *)    false ;;
-            esac
-        then
-            arg=$( cygpath --path --ignore --mixed "$arg" )
-        fi
-        # Roll the args list around exactly as many times as the number of
-        # args, so each arg winds up back in the position where it started, but
-        # possibly modified.
-        #
-        # NB: a `for` loop captures its iteration list before it begins, so
-        # changing the positional parameters here affects neither the number of
-        # iterations, nor the values presented in `arg`.
-        shift                   # remove old arg
-        set -- "$@" "$arg"      # push replacement arg
-    done
-fi
-
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
-
-# Collect all arguments for the java command:
-#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
-#     and any embedded shellness will be escaped.
-#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
-#     treated as '${Hostname}' itself on the command line.
-
-set -- \
-        "-Dorg.gradle.appname=$APP_BASE_NAME" \
-        -classpath "$CLASSPATH" \
-        org.gradle.wrapper.GradleWrapperMain \
-        "$@"
-
-# Stop when "xargs" is not available.
-if ! command -v xargs >/dev/null 2>&1
-then
-    die "xargs is not available"
-fi
-
-# Use "xargs" to parse quoted args.
-#
-# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
-#
-# In Bash we could simply go:
-#
-#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
-#   set -- "${ARGS[@]}" "$@"
-#
-# but POSIX shell has neither arrays nor command substitution, so instead we
-# post-process each arg (as a line of input to sed) to backslash-escape any
-# character that might be a shell metacharacter, then use eval to reverse
-# that process (while maintaining the separation between arguments), and wrap
-# the whole thing up as a single "set" statement.
-#
-# This will of course break if any of these variables contains a newline or
-# an unmatched quote.
-#
-
-eval "set -- $(
-        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
-        xargs -n1 |
-        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
-        tr '\n' ' '
-    )" '"$@"'
-
-exec "$JAVACMD" "$@"
diff --git a/Samples/SwiftAndJavaJarSampleLib/gradlew b/Samples/SwiftAndJavaJarSampleLib/gradlew
new file mode 120000
index 00000000..343e0d2c
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/gradlew
@@ -0,0 +1 @@
+../../gradlew
\ No newline at end of file
diff --git a/Samples/SwiftAndJavaJarSampleLib/gradlew.bat b/Samples/SwiftAndJavaJarSampleLib/gradlew.bat
deleted file mode 100644
index 9b42019c..00000000
--- a/Samples/SwiftAndJavaJarSampleLib/gradlew.bat
+++ /dev/null
@@ -1,94 +0,0 @@
-@rem
-@rem Copyright 2015 the original author or authors.
-@rem
-@rem Licensed under the Apache License, Version 2.0 (the "License");
-@rem you may not use this file except in compliance with the License.
-@rem You may obtain a copy of the License at
-@rem
-@rem      https://www.apache.org/licenses/LICENSE-2.0
-@rem
-@rem Unless required by applicable law or agreed to in writing, software
-@rem distributed under the License is distributed on an "AS IS" BASIS,
-@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-@rem See the License for the specific language governing permissions and
-@rem limitations under the License.
-@rem
-@rem SPDX-License-Identifier: Apache-2.0
-@rem
-
-@if "%DEBUG%"=="" @echo off
-@rem ##########################################################################
-@rem
-@rem  Gradle startup script for Windows
-@rem
-@rem ##########################################################################
-
-@rem Set local scope for the variables with windows NT shell
-if "%OS%"=="Windows_NT" setlocal
-
-set DIRNAME=%~dp0
-if "%DIRNAME%"=="" set DIRNAME=.
-@rem This is normally unused
-set APP_BASE_NAME=%~n0
-set APP_HOME=%DIRNAME%
-
-@rem Resolve any "." and ".." in APP_HOME to make it shorter.
-for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
-
-@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
-
-@rem Find java.exe
-if defined JAVA_HOME goto findJavaFromJavaHome
-
-set JAVA_EXE=java.exe
-%JAVA_EXE% -version >NUL 2>&1
-if %ERRORLEVEL% equ 0 goto execute
-
-echo. 1>&2
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
-echo. 1>&2
-echo Please set the JAVA_HOME variable in your environment to match the 1>&2
-echo location of your Java installation. 1>&2
-
-goto fail
-
-:findJavaFromJavaHome
-set JAVA_HOME=%JAVA_HOME:"=%
-set JAVA_EXE=%JAVA_HOME%/bin/java.exe
-
-if exist "%JAVA_EXE%" goto execute
-
-echo. 1>&2
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
-echo. 1>&2
-echo Please set the JAVA_HOME variable in your environment to match the 1>&2
-echo location of your Java installation. 1>&2
-
-goto fail
-
-:execute
-@rem Setup the command line
-
-set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
-
-
-@rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
-
-:end
-@rem End local scope for the variables with windows NT shell
-if %ERRORLEVEL% equ 0 goto mainEnd
-
-:fail
-rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
-rem the _cmd.exe /c_ return code!
-set EXIT_CODE=%ERRORLEVEL%
-if %EXIT_CODE% equ 0 set EXIT_CODE=1
-if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
-exit /b %EXIT_CODE%
-
-:mainEnd
-if "%OS%"=="Windows_NT" endlocal
-
-:omega
diff --git a/Samples/SwiftAndJavaJarSampleLib/gradlew.bat b/Samples/SwiftAndJavaJarSampleLib/gradlew.bat
new file mode 120000
index 00000000..cb5a9464
--- /dev/null
+++ b/Samples/SwiftAndJavaJarSampleLib/gradlew.bat
@@ -0,0 +1 @@
+../../gradlew.bat
\ No newline at end of file