Fix JNI caching for native threads

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -119,6 +119,8 @@ extension JNISwift2JavaGenerator {
   private func printGlobalSwiftThunkSources(_ printer: inout CodePrinter) throws {
     printHeader(&printer)
 
+    printJNIOnLoad(&printer)
+
     for decl in analysis.importedGlobalFuncs {
       printSwiftFunctionThunk(&printer, decl)
       printer.println()
@@ -130,6 +132,18 @@ extension JNISwift2JavaGenerator {
     }
   }
 
+  private func printJNIOnLoad(_ printer: inout CodePrinter) {
+    printer.print(
+      """
+      @_cdecl("JNI_OnLoad")
+      func JNI_OnLoad(javaVM: JavaVMPointer, reserved: UnsafeMutableRawPointer) -> jint {
+        SwiftJavaRuntimeSupport._JNI_OnLoad(javaVM, reserved)
+        return JNI_VERSION_1_6
+      }
+      """
+    )
+  }
+
   private func printNominalTypeThunks(_ printer: inout CodePrinter, _ type: ImportedNominalType) throws {
     printHeader(&printer)
 
@@ -222,7 +236,7 @@ extension JNISwift2JavaGenerator {
       let methodSignature = MethodSignature(resultType: .void, parameterTypes: enumCase.parameterConversions.map(\.native.javaType))
       let methods = #"[.init(name: "<init>", signature: "\#(methodSignature.mangledName)")]"#
 
-      return #"_JNIMethodIDCache(environment: try! JavaVirtualMachine.shared().environment(), className: "\#(nativeParametersClassName)", methods: \#(methods))"#
+      return #"_JNIMethodIDCache(className: "\#(nativeParametersClassName)", methods: \#(methods))"#
   }
 
   private func printEnumGetAsCaseThunk(

Sources/SwiftJava/generated/JavaThread.swift

@@ -0,0 +1,229 @@
+// Auto-generated by Java-to-Swift wrapper generator.
+import CSwiftJavaJNI
+
+@JavaClass("java.lang.Thread")
+open class JavaThread: JavaObject {
+  @JavaMethod
+  @_nonoverride public convenience init(_ arg0: String, environment: JNIEnvironment? = nil)
+
+  @JavaMethod
+  @_nonoverride public convenience init(environment: JNIEnvironment? = nil)
+
+  @JavaMethod
+  open func getName() -> String
+
+  @JavaMethod
+  open func run()
+
+  @JavaMethod
+  open func interrupt()
+
+  @JavaMethod
+  open override func toString() -> String
+
+  @JavaMethod
+  open override func clone() throws -> JavaObject!
+
+  @JavaMethod
+  open func join(_ arg0: Int64, _ arg1: Int32) throws
+
+  @JavaMethod
+  open func join() throws
+
+  @JavaMethod
+  open func join(_ arg0: Int64) throws
+
+  @JavaMethod
+  open func setContextClassLoader(_ arg0: JavaClassLoader?)
+
+  @JavaMethod
+  open func setPriority(_ arg0: Int32)
+
+  @JavaMethod
+  open func setDaemon(_ arg0: Bool)
+
+  @JavaMethod
+  open func start()
+
+  @JavaMethod
+  open func getPriority() -> Int32
+
+  @JavaMethod
+  open func isDaemon() -> Bool
+
+  @JavaMethod
+  open func getContextClassLoader() -> JavaClassLoader!
+
+  @JavaMethod
+  open func isVirtual() -> Bool
+
+  @JavaMethod
+  open func isAlive() -> Bool
+
+  @JavaMethod
+  open func threadId() -> Int64
+
+  @JavaMethod
+  open func getUncaughtExceptionHandler() -> JavaThread.UncaughtExceptionHandler!
+
+  @JavaMethod
+  open func stop()
+
+  @JavaMethod
+  open func isInterrupted() -> Bool
+
+  @JavaMethod
+  open func setName(_ arg0: String)
+
+  @JavaMethod
+  open func checkAccess()
+
+  @JavaMethod
+  open func getId() -> Int64
+
+  @JavaMethod
+  open func setUncaughtExceptionHandler(_ arg0: JavaThread.UncaughtExceptionHandler?)
+}
+extension JavaThread {
+  @JavaInterface("java.lang.Thread$Builder")
+  public struct Builder {
+  @JavaMethod
+  public func name(_ arg0: String) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func name(_ arg0: String, _ arg1: Int64) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func uncaughtExceptionHandler(_ arg0: JavaThread.UncaughtExceptionHandler?) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func inheritInheritableThreadLocals(_ arg0: Bool) -> JavaThread.Builder!
+  }
+}
+extension JavaThread.Builder {
+  @JavaInterface("java.lang.Thread$Builder$OfPlatform", extends: JavaThread.Builder.self)
+  public struct OfPlatform {
+  @JavaMethod
+  public func name(_ arg0: String, _ arg1: Int64) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func name(_ arg0: String, _ arg1: Int64) -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func name(_ arg0: String) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func name(_ arg0: String) -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func priority(_ arg0: Int32) -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func daemon() -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func daemon(_ arg0: Bool) -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func uncaughtExceptionHandler(_ arg0: JavaThread.UncaughtExceptionHandler?) -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func uncaughtExceptionHandler(_ arg0: JavaThread.UncaughtExceptionHandler?) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func stackSize(_ arg0: Int64) -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func inheritInheritableThreadLocals(_ arg0: Bool) -> JavaThread.Builder.OfPlatform!
+
+  @JavaMethod
+  public func inheritInheritableThreadLocals(_ arg0: Bool) -> JavaThread.Builder!
+  }
+}
+extension JavaThread.Builder {
+  @JavaInterface("java.lang.Thread$Builder$OfVirtual", extends: JavaThread.Builder.self)
+  public struct OfVirtual {
+  @JavaMethod
+  public func name(_ arg0: String, _ arg1: Int64) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func name(_ arg0: String, _ arg1: Int64) -> JavaThread.Builder.OfVirtual!
+
+  @JavaMethod
+  public func name(_ arg0: String) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func name(_ arg0: String) -> JavaThread.Builder.OfVirtual!
+
+  @JavaMethod
+  public func uncaughtExceptionHandler(_ arg0: JavaThread.UncaughtExceptionHandler?) -> JavaThread.Builder!
+
+  @JavaMethod
+  public func uncaughtExceptionHandler(_ arg0: JavaThread.UncaughtExceptionHandler?) -> JavaThread.Builder.OfVirtual!
+
+  @JavaMethod
+  public func inheritInheritableThreadLocals(_ arg0: Bool) -> JavaThread.Builder.OfVirtual!
+
+  @JavaMethod
+  public func inheritInheritableThreadLocals(_ arg0: Bool) -> JavaThread.Builder!
+  }
+}
+extension JavaThread {
+  @JavaInterface("java.lang.Thread$UncaughtExceptionHandler")
+  public struct UncaughtExceptionHandler {
+  @JavaMethod
+  public func uncaughtException(_ arg0: JavaThread?, _ arg1: Throwable?)
+  }
+}
+extension JavaClass<JavaThread> {
+  @JavaStaticField(isFinal: true)
+  public var MIN_PRIORITY: Int32
+
+  @JavaStaticField(isFinal: true)
+  public var NORM_PRIORITY: Int32
+
+  @JavaStaticField(isFinal: true)
+  public var MAX_PRIORITY: Int32
+
+  @JavaStaticMethod
+  public func currentThread() -> JavaThread!
+
+  @JavaStaticMethod
+  public func onSpinWait()
+
+  @JavaStaticMethod
+  public func holdsLock(_ arg0: JavaObject?) -> Bool
+
+  @JavaStaticMethod
+  public func interrupted() -> Bool
+
+  @JavaStaticMethod
+  public func activeCount() -> Int32
+
+  @JavaStaticMethod
+  public func enumerate(_ arg0: [JavaThread?]) -> Int32
+
+  @JavaStaticMethod
+  public func yield()
+
+  @JavaStaticMethod
+  public func sleep(_ arg0: Int64) throws
+
+  @JavaStaticMethod
+  public func sleep(_ arg0: Int64, _ arg1: Int32) throws
+
+  @JavaStaticMethod
+  public func ofPlatform() -> JavaThread.Builder.OfPlatform!
+
+  @JavaStaticMethod
+  public func ofVirtual() -> JavaThread.Builder.OfVirtual!
+
+  @JavaStaticMethod
+  public func dumpStack()
+
+  @JavaStaticMethod
+  public func setDefaultUncaughtExceptionHandler(_ arg0: JavaThread.UncaughtExceptionHandler?)
+
+  @JavaStaticMethod
+  public func getDefaultUncaughtExceptionHandler() -> JavaThread.UncaughtExceptionHandler!
+}

Sources/SwiftJava/swift-java.config

@@ -23,6 +23,7 @@
     "java.lang.Void" : "JavaVoid",
     "java.lang.CharSequence": "CharSequence",
     "java.lang.Appendable": "Appendable",
+    "java.lang.Thread": "JavaThread",
     "java.util.Optional": "JavaOptional",
     "java.util.OptionalDouble": "JavaOptionalDouble",
     "java.util.OptionalInt": "JavaOptionalInt",

Sources/SwiftJavaRuntimeSupport/JNI.swift

@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftJava
+import CSwiftJavaJNI
+
+final class JNI {
+  static var shared: JNI!
+
+  let applicationClassLoader: JavaClassLoader
+
+  init(fromVM javaVM: JavaVirtualMachine) {
+    self.applicationClassLoader = try! JavaClass<JavaThread>(environment: javaVM.environment()).currentThread().getContextClassLoader()
+  }
+}
+
+// Called by generated code, and not automatically by Java.
+public func _JNI_OnLoad(_ javaVM: JavaVMPointer, _ reserved: UnsafeMutableRawPointer) {
+  JNI.shared = JNI(fromVM: JavaVirtualMachine(adoptingJVM: javaVM))
+}

Sources/SwiftJavaRuntimeSupport/JNIMethodIDCaches.swift

@@ -27,7 +27,6 @@ extension _JNIMethodIDCache {
     )
 
     private static let cache = _JNIMethodIDCache(
-      environment: try! JavaVirtualMachine.shared().environment(),
       className: "java/util/concurrent/CompletableFuture",
       methods: [completeMethod, completeExceptionallyMethod]
     )
@@ -59,7 +58,6 @@ extension _JNIMethodIDCache {
     )
 
     private static let cache = _JNIMethodIDCache(
-      environment: try! JavaVirtualMachine.shared().environment(),
       className: "org/swift/swiftkit/core/SimpleCompletableFuture",
       methods: [completeMethod, completeExceptionallyMethod]
     )
@@ -81,7 +79,6 @@ extension _JNIMethodIDCache {
     private static let messageConstructor = Method(name: "<init>", signature: "(Ljava/lang/String;)V")
 
     private static let cache = _JNIMethodIDCache(
-      environment: try! JavaVirtualMachine.shared().environment(),
       className: "java/lang/Exception",
       methods: [messageConstructor]
     )

Sources/SwiftJavaRuntimeSupport/_JNIBoxedConversions.swift

@@ -26,47 +26,39 @@ public enum _JNIBoxedConversions {
   private static let doubleMethod = _JNIMethodIDCache.Method(name: "valueOf", signature: "(D)Ljava/lang/Double;", isStatic: true)
 
   private static let booleanCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Boolean",
     methods: [booleanMethod]
   )
 
   private static let byteCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Byte",
     methods: [byteMethod]
   )
   private static let charCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Character",
     methods: [charMethod]
   )
 
   private static let shortCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Short",
     methods: [shortMethod]
   )
   private static let intCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Integer",
     methods: [intMethod]
   )
 
   private static let longCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Long",
     methods: [longMethod]
   )
 
   private static let floatCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Float",
     methods: [floatMethod]
   )
 
   private static let doubleCache = _JNIMethodIDCache(
-    environment: try! JavaVirtualMachine.shared().environment(),
     className: "java/lang/Double",
     methods: [doubleMethod]
   )