Add JExtract JNI sample app

.github/workflows/pull_request.yml

@@ -78,6 +78,7 @@ jobs:
           'JavaSieve',
           'SwiftAndJavaJarSampleLib',
           'SwiftKitSampleApp',
+          'JExtractJNISampleApp'
         ]
     container:
       image: ${{ (contains(matrix.swift_version, 'nightly') && 'swiftlang/swift') || 'swift' }}:${{ matrix.swift_version }}-${{ matrix.os_version }}

Samples/JExtractJNISampleApp/Package.swift

@@ -0,0 +1,79 @@
+// 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: "JExtractJNISampleApp",
+  platforms: [
+    .macOS(.v15)
+  ],
+  products: [
+    .library(
+      name: "MySwiftLibrary",
+      type: .dynamic,
+      targets: ["MySwiftLibrary"]
+    )
+
+  ],
+  dependencies: [
+    .package(name: "swift-java", path: "../../")
+  ],
+  targets: [
+    .target(
+      name: "MySwiftLibrary",
+      dependencies: [
+        .product(name: "JavaKit", package: "swift-java"),
+        .product(name: "JavaRuntime", package: "swift-java"),
+        .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")
+      ]
+    )
+  ]
+)

Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/MySwiftLibrary.swift

@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 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: Int64) {
+  p("i:\(i)")
+}
+
+public func globalMakeInt() -> Int64 {
+  return 42
+}
+
+public func globalWriteString(string: String) -> Int64 {
+  return Int64(string.count)
+}
+
+public func globalTakeIntInt(i: Int64, j: Int64) {
+  p("i:\(i), j:\(j)")
+}
+
+// ==== Internal helpers
+
+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

Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/swift-java.config

@@ -0,0 +1,4 @@
+{
+  "javaPackage": "com.example.swift",
+  "mode": "jni"
+}

Samples/JExtractJNISampleApp/build.gradle

@@ -0,0 +1,195 @@
+//===----------------------------------------------------------------------===//
+//
+// 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.*
+import kotlinx.serialization.json.*
+
+plugins {
+    id("build-logic.java-application-conventions")
+    id("me.champeau.jmh") version "0.7.2"
+}
+
+group = "org.swift.swiftkit"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(24))
+    }
+}
+
+def swiftProductsWithJExtractPlugin() {
+    def stdout = new ByteArrayOutputStream()
+    def stderr = new ByteArrayOutputStream()
+
+    def result = exec {
+        commandLine 'swift', 'package', 'describe', '--type', 'json'
+        standardOutput = stdout
+        errorOutput = stderr
+        ignoreExitValue = true
+    }
+
+    def jsonOutput = stdout.toString()
+
+    if (result.exitValue == 0) {
+        def json = new JsonSlurper().parseText(jsonOutput)
+        def products = json.targets
+                .findAll { target ->
+                    target.product_dependencies?.contains("JExtractSwiftPlugin")
+                }
+                .collectMany { target ->
+                    target.product_memberships ?: []
+                }
+        return products
+    } else {
+        logger.warn("Command failed: ${stderr.toString()}")
+        return []
+    }
+}
+
+
+def swiftCheckValid = tasks.register("swift-check-valid", Exec) {
+    commandLine "swift"
+    args("-version")
+}
+
+def jextract = tasks.register("jextract", Exec) {
+    description = "Generate Java wrappers for swift target"
+    dependsOn swiftCheckValid
+
+    // 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"))
+
+    // If the package description changes, we should execute jextract again, maybe we added jextract to new targets
+    inputs.file(new File(projectDir, "Package.swift"))
+
+    // monitor all targets/products which depend on the JExtract plugin
+    swiftProductsWithJExtractPlugin().each {
+        logger.info("[swift-java:jextract (Gradle)] Swift input target: ${it}")
+        inputs.dir(new File(layout.projectDirectory.asFile, "Sources/${it}".toString()))
+    }
+    outputs.dir(layout.buildDirectory.dir("../.build/plugins/outputs/${layout.projectDirectory.asFile.getName().toLowerCase()}"))
+
+    File baseSwiftPluginOutputsDir = layout.buildDirectory.dir("../.build/plugins/outputs/").get().asFile
+    if (!baseSwiftPluginOutputsDir.exists()) {
+        baseSwiftPluginOutputsDir.mkdirs()
+    }
+    Files.walk(layout.buildDirectory.dir("../.build/plugins/outputs/").get().asFile.toPath()).each {
+        // Add any Java sources generated by the plugin to our sourceSet
+        if (it.endsWith("JExtractSwiftPlugin/src/generated/java")) {
+            outputs.dir(it)
+        }
+    }
+
+    workingDir = layout.projectDirectory
+    commandLine "swift"
+    args("build") // since Swift targets which need to be jextract-ed have the jextract build plugin, we just need to build
+    // If we wanted to execute a specific subcommand, we can like this:
+    //     args("run",/*
+    //             "swift-java", "jextract",
+    //             "--swift-module", "MySwiftLibrary",
+    //             // java.package is obtained from the swift-java.config in the swift module
+    //             "--output-java", "${layout.buildDirectory.dir(".build/plugins/outputs/${layout.projectDirectory.asFile.getName().toLowerCase()}/JExtractSwiftPlugin/src/generated/java").get()}",
+    //             "--output-swift", "${layout.buildDirectory.dir(".build/plugins/outputs/${layout.projectDirectory.asFile.getName().toLowerCase()}/JExtractSwiftPlugin/Sources").get()}",
+    //             "--log-level", (logging.level <= LogLevel.INFO ? "debug" :  */"info")
+    //     )
+}
+
+// Add the java-swift generated Java sources
+sourceSets {
+    main {
+        java {
+            srcDir(jextract)
+        }
+    }
+    test {
+        java {
+            srcDir(jextract)
+        }
+    }
+    jmh {
+        java {
+            srcDir(jextract)
+        }
+    }
+}
+
+tasks.build {
+    dependsOn("jextract")
+}
+
+
+def cleanSwift = tasks.register("cleanSwift", Exec) {
+    workingDir = layout.projectDirectory
+    commandLine "swift"
+    args("package", "clean")
+}
+tasks.clean {
+    dependsOn("cleanSwift")
+}
+
+dependencies {
+    implementation(project(':SwiftKit'))
+
+    testImplementation(platform("org.junit:junit-bom:5.10.0"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+}
+
+tasks.named('test', Test) {
+    useJUnitPlatform()
+}
+
+application {
+    mainClass = "com.example.swift.HelloJava2SwiftJNI"
+
+    applicationDefaultJvmArgs = [
+        "--enable-native-access=ALL-UNNAMED",
+
+        // Include the library paths where our dylibs are that we want to load and call
+        "-Djava.library.path=" +
+                (BuildUtils.javaLibraryPaths(rootDir) +
+                 BuildUtils.javaLibraryPaths(project.projectDir)).join(":"),
+
+
+        // Enable tracing downcalls (to Swift)
+        "-Djextract.trace.downcalls=true"
+    ]
+}
+
+String jmhIncludes = findProperty("jmhIncludes")
+
+jmh {
+    if (jmhIncludes != null) {
+        includes = [jmhIncludes]
+    }
+
+    jvmArgsAppend = [
+        "--enable-native-access=ALL-UNNAMED",
+
+        "-Djava.library.path=" +
+                (BuildUtils.javaLibraryPaths(rootDir) +
+                 BuildUtils.javaLibraryPaths(project.projectDir)).join(":"),
+
+        // Enable tracing downcalls (to Swift)
+        "-Djextract.trace.downcalls=false"
+    ]
+}

Samples/JExtractJNISampleApp/ci-validate.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set -x
+set -e
+
+./gradlew run

Samples/JExtractJNISampleApp/gradlew

@@ -0,0 +1 @@
+../../gradlew

Samples/JExtractJNISampleApp/gradlew.bat

@@ -0,0 +1 @@
+../../gradlew.bat