Revert "make SwiftJava a dynamic lib and add class lookup fallbacks (swiftlang#493)"

This reverts commit 0685f55.

Author: ktoso

Package.swift

@@ -100,7 +100,6 @@ let package = Package(
     // ==== SwiftJava (i.e. calling Java directly Swift utilities)
     .library(
       name: "SwiftJava",
-      type: .dynamic,
       targets: ["SwiftJava"]
     ),
 

Samples/SwiftAndJavaJarSampleLib/Package.swift

@@ -63,9 +63,7 @@ let package = Package(
     .target(
       name: "MySwiftLibrary",
       dependencies: [
-        .product(name: "SwiftJava", package: "swift-java"),
-        .product(name: "CSwiftJavaJNI", package: "swift-java"),
-        .product(name: "SwiftRuntimeFunctions", package: "swift-java")
+        .product(name: "SwiftRuntimeFunctions", package: "swift-java"),
       ],
       exclude: [
         "swift-java.config",

Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator.swift

@@ -195,7 +195,6 @@ extension FFMSwift2JavaGenerator {
         private static final boolean INITIALIZED_LIBS = initializeLibs();
         static boolean initializeLibs() {
             System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_CORE);
-            System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
             System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_RUNTIME_FUNCTIONS);
             System.loadLibrary(LIB_NAME);
             return true;
@@ -346,7 +345,6 @@ extension FFMSwift2JavaGenerator {
         private static SymbolLookup getSymbolLookup() {
             if (SwiftLibraries.AUTO_LOAD_LIBS) {
                 System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_CORE);
-                System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
                 System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_RUNTIME_FUNCTIONS);
                 System.loadLibrary(LIB_NAME);
             }

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -99,7 +99,6 @@ extension JNISwift2JavaGenerator {
         static final String LIB_NAME = "\(swiftModuleName)";
         
         static {
-          System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
           System.loadLibrary(LIB_NAME);
         }
         """
@@ -170,7 +169,6 @@ extension JNISwift2JavaGenerator {
         @SuppressWarnings("unused")
         private static final boolean INITIALIZED_LIBS = initializeLibs();
         static boolean initializeLibs() {
-            System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
             System.loadLibrary(LIB_NAME);
             return true;
         }

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -162,7 +162,7 @@ extension JNISwift2JavaGenerator {
       // If the underlying translated method requires
       // a SwiftArena, we pass in the global arena
       if translatedDecl.translatedFunctionSignature.requiresSwiftArena {
-        upcallArguments.append("JavaSwiftArena.defaultAutoArena")
+        upcallArguments.append("JNI.shared.defaultAutoArena")
       }
 
       let tryClause = function.originalFunctionSignature.isThrowing ? "try " : ""
@@ -201,6 +201,8 @@ extension JNISwift2JavaGenerator {
   private func printGlobalSwiftThunkSources(_ printer: inout CodePrinter) throws {
     printHeader(&printer)
 
+    printJNIOnLoad(&printer)
+
     for decl in analysis.importedGlobalFuncs {
       printSwiftFunctionThunk(&printer, decl)
       printer.println()
@@ -212,6 +214,18 @@ 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)
 

Sources/SwiftJava/AnyJavaObject.swift

@@ -102,41 +102,23 @@ extension AnyJavaObject {
     in environment: JNIEnvironment,
     _ body: (jclass) throws -> Result
   ) throws -> Result {
-    do {
-      let resolvedClass = try environment.translatingJNIExceptions {
-        environment.interface.FindClass(
-          environment,
-          fullJavaClassNameWithSlashes
-        )
-      }!
-      return try body(resolvedClass)
-    } catch {
-      // If we are in a Java environment where we have loaded
-      // SwiftJava dynamically, we have access to the application class loader
-      // so lets try that as as a fallback
-      if let applicationClassLoader = JNI.shared?.applicationClassLoader {
-        return try _withJNIClassFromCustomClassLoader(
-          applicationClassLoader,
-          in: environment
-        ) { applicationLoadedClass in
-          return try body(applicationLoadedClass)
-        }
-      } else {
-        throw error
-      }
-    }
+    let resolvedClass = try environment.translatingJNIExceptions {
+      environment.interface.FindClass(
+        environment,
+        fullJavaClassNameWithSlashes
+      )
+    }!
+    return try body(resolvedClass)
   }
 
   /// Retrieve the Java class for this type using a specific class loader.
   private static func _withJNIClassFromCustomClassLoader<Result>(
     _ classLoader: JavaClassLoader,
     in environment: JNIEnvironment,
-    _ body: (jclass) throws -> Result
+    _ body: (jclass?) throws -> Result
   ) throws -> Result {
-    let resolvedClass = try classLoader.findClass(fullJavaClassName)
-    // OK to force unwrap, as classLoader will throw ClassNotFoundException
-    // if the class cannot be found.
-    return try body(resolvedClass!.javaThis)
+    let resolvedClass = try? classLoader.findClass(fullJavaClassName)
+    return try body(resolvedClass?.javaThis)
   }
 
   /// Retrieve the Java class for this type and execute body().
@@ -147,15 +129,16 @@ extension AnyJavaObject {
   ) throws -> Result {
     if let AnyJavaObjectWithCustomClassLoader = self as? AnyJavaObjectWithCustomClassLoader.Type,
        let customClassLoader = try AnyJavaObjectWithCustomClassLoader.getJavaClassLoader(in: environment) {
-      do {
-        return try _withJNIClassFromCustomClassLoader(customClassLoader, in: environment) { clazz in
-          return try body(clazz)
+      try _withJNIClassFromCustomClassLoader(customClassLoader, in: environment) { clazz in
+        guard let clazz else {
+          // If the custom class loader did not find the class
+          // let's look in the default class loader.
+          return try _withJNIClassFromDefaultClassLoader(in: environment, body)
         }
-      } catch {
-        return try _withJNIClassFromDefaultClassLoader(in: environment, body)
+        return try body(clazz)
       }
     } else {
-      return try _withJNIClassFromDefaultClassLoader(in: environment, body)
+      try _withJNIClassFromDefaultClassLoader(in: environment, body)
     }
   }
 }

Sources/SwiftJava/JVM/JavaVirtualMachine.swift

@@ -220,7 +220,7 @@ extension JavaVirtualMachine {
   /// TODO: If the use of the lock itself ends up being slow, we could
   /// use an atomic here instead because our access pattern is fairly
   /// simple.
-  static let sharedJVM: LockedState<JavaVirtualMachine?> = .init(initialState: nil)
+  private static let sharedJVM: LockedState<JavaVirtualMachine?> = .init(initialState: nil)
 
   /// Access the shared Java Virtual Machine instance.
   ///

Sources/SwiftJava/JNI.swift Sources/SwiftJavaRuntimeSupport/JNI.swiftSources/SwiftJava/JNI.swift renamed to Sources/SwiftJavaRuntimeSupport/JNI.swift

@@ -12,6 +12,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+import SwiftJava
 import CSwiftJavaJNI
 
 /// A type that represents the shared JNI environment
@@ -20,28 +21,36 @@ import CSwiftJavaJNI
 /// This is initialized when the `JNI_OnLoad` is triggered,
 /// which happens when you call `System.loadLibrary(...)`
 /// from Java.
-package final class JNI {
+public final class JNI {
   /// The shared JNI object, initialized by `JNI_OnLoad`
-  ///
-  /// This may be `nil` in the case where `SwiftJava` is not loaded as a dynamic lib
-  /// by the Java sources.
-  package fileprivate(set) static var shared: JNI?
+  public fileprivate(set) static var shared: JNI!
 
   /// The default application class loader
-  package let applicationClassLoader: JavaClassLoader
+  public let applicationClassLoader: JavaClassLoader
+
+  /// The default auto arena of SwiftKitCore
+  public let defaultAutoArena: JavaSwiftArena
 
   init(fromVM javaVM: JavaVirtualMachine) {
-    // Update the global JavaVM
-    JavaVirtualMachine.sharedJVM.withLock {
-      $0 = javaVM
-    }
     let environment = try! javaVM.environment()
+
     self.applicationClassLoader = try! JavaClass<JavaThread>(environment: environment).currentThread().getContextClassLoader()
+
+    // Find global arena
+    let swiftMemoryClass = environment.interface.FindClass(environment, "org/swift/swiftkit/core/SwiftMemoryManagement")!
+    let arenaFieldID = environment.interface.GetStaticFieldID(
+        environment,
+        swiftMemoryClass,
+        "DEFAULT_SWIFT_JAVA_AUTO_ARENA",
+        JavaSwiftArena.mangledName
+    )
+    let localObject = environment.interface.GetStaticObjectField(environment, swiftMemoryClass, arenaFieldID)!
+    self.defaultAutoArena = JavaSwiftArena(javaThis: localObject, environment: environment)
+    environment.interface.DeleteLocalRef(environment, localObject)
   }
 }
 
-@_cdecl("JNI_OnLoad")
-func SwiftJava_JNI_OnLoad(javaVM: JavaVMPointer, reserved: UnsafeMutableRawPointer) -> jint {
+// Called by generated code, and not automatically by Java.
+public func _JNI_OnLoad(_ javaVM: JavaVMPointer, _ reserved: UnsafeMutableRawPointer) {
   JNI.shared = JNI(fromVM: JavaVirtualMachine(adoptingJVM: javaVM))
-  return JNI_VERSION_1_6
 }

Sources/SwiftJavaRuntimeSupport/_JNIMethodIDCache.swift

@@ -55,8 +55,7 @@ public final class _JNIMethodIDCache: Sendable {
       // Clear any ClassNotFound exceptions from FindClass
       environment.interface.ExceptionClear(environment)
 
-      // OK to force unwrap, we are in a jextract environment.
-      if let javaClass = try? JNI.shared!.applicationClassLoader.loadClass(
+      if let javaClass = try? JNI.shared.applicationClassLoader.loadClass(
         className.replacingOccurrences(of: "/", with: ".")
       ) {
         clazz = javaClass.javaThis

Sources/SwiftJavaRuntimeSupport/generated/JavaJNISwiftInstance.swift

@@ -20,7 +20,6 @@ public struct JavaJNISwiftInstance: AnyJavaObjectWithCustomClassLoader {
   public func memoryAddress() -> Int64
 
   public static func getJavaClassLoader(in environment: JNIEnvironment) throws -> JavaClassLoader! {
-    // OK to force unwrap, we are in a jextract environment.
-    JNI.shared!.applicationClassLoader
+    JNI.shared.applicationClassLoader
   }
 }