[SwiftKit] Move 'selfPointer' to 'JNISwiftInstance' & downcall trace logs

Samples/SwiftKitSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java

@@ -18,6 +18,7 @@
 
 // Import javakit/swiftkit support libraries
 
+import org.swift.swiftkit.core.CallTraces;
 import org.swift.swiftkit.core.SwiftLibraries;
 import org.swift.swiftkit.ffm.AllocatingSwiftArena;
 import org.swift.swiftkit.ffm.SwiftRuntime;
@@ -43,30 +44,30 @@ static void examples() {
 
         long cnt = MySwiftLibrary.globalWriteString("String from Java");
 
-        SwiftRuntime.trace("count = " + cnt);
+        CallTraces.trace("count = " + cnt);
 
         MySwiftLibrary.globalCallMeRunnable(() -> {
-            SwiftRuntime.trace("running runnable");
+            CallTraces.trace("running runnable");
         });
 
-        SwiftRuntime.trace("getGlobalBuffer().byteSize()=" + MySwiftLibrary.getGlobalBuffer().byteSize());
+        CallTraces.trace("getGlobalBuffer().byteSize()=" + MySwiftLibrary.getGlobalBuffer().byteSize());
 
         MySwiftLibrary.withBuffer((buf) -> {
-            SwiftRuntime.trace("withBuffer{$0.byteSize()}=" + buf.byteSize());
+            CallTraces.trace("withBuffer{$0.byteSize()}=" + buf.byteSize());
         });
         // Example of using an arena; MyClass.deinit is run at end of scope
         try (var arena = AllocatingSwiftArena.ofConfined()) {
             MySwiftClass obj = MySwiftClass.init(2222, 7777, arena);
 
             // just checking retains/releases work
-            SwiftRuntime.trace("retainCount = " + SwiftRuntime.retainCount(obj));
+            CallTraces.trace("retainCount = " + SwiftRuntime.retainCount(obj));
             SwiftRuntime.retain(obj);
-            SwiftRuntime.trace("retainCount = " + SwiftRuntime.retainCount(obj));
+            CallTraces.trace("retainCount = " + SwiftRuntime.retainCount(obj));
             SwiftRuntime.release(obj);
-            SwiftRuntime.trace("retainCount = " + SwiftRuntime.retainCount(obj));
+            CallTraces.trace("retainCount = " + SwiftRuntime.retainCount(obj));
 
             obj.setCounter(12);
-            SwiftRuntime.trace("obj.counter = " + obj.getCounter());
+            CallTraces.trace("obj.counter = " + obj.getCounter());
 
             obj.voidMethod();
             obj.takeIntMethod(42);
@@ -75,22 +76,22 @@ static void examples() {
             otherObj.voidMethod();
 
             MySwiftStruct swiftValue = MySwiftStruct.init(2222, 1111, arena);
-            SwiftRuntime.trace("swiftValue.capacity = " + swiftValue.getCapacity());
+            CallTraces.trace("swiftValue.capacity = " + swiftValue.getCapacity());
             swiftValue.withCapLen((cap, len) -> {
-                SwiftRuntime.trace("withCapLenCallback: cap=" + cap + ", len=" + len);
+                CallTraces.trace("withCapLenCallback: cap=" + cap + ", len=" + len);
             });
         }
 
         // Example of using 'Data'.
         try (var arena = AllocatingSwiftArena.ofConfined()) {
             var origBytes = arena.allocateFrom("foobar");
             var origDat = Data.init(origBytes, origBytes.byteSize(), arena);
-            SwiftRuntime.trace("origDat.count = " + origDat.getCount());
+            CallTraces.trace("origDat.count = " + origDat.getCount());
 
             var retDat = MySwiftLibrary.globalReceiveReturnData(origDat, arena);
             retDat.withUnsafeBytes((retBytes) -> {
                 var str = retBytes.getString(0);
-                SwiftRuntime.trace("retStr=" + str);
+                CallTraces.trace("retStr=" + str);
             });
         }
 

Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -116,8 +116,8 @@ extension FFMSwift2JavaGenerator {
       """
       public static \(returnTy) call(\(paramsStr)) {
         try {
-          if (SwiftRuntime.TRACE_DOWNCALLS) {
-            SwiftRuntime.traceDowncall(\(argsStr));
+          if (CallTraces.TRACE_DOWNCALLS) {
+            CallTraces.traceDowncall(\(argsStr));
           }
           \(maybeReturn)HANDLE.invokeExact(\(argsStr));
         } catch (Throwable ex$) {

Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -131,6 +131,7 @@ extension FFMSwift2JavaGenerator {
       }
       printer.print("import \(module)")
     }
+    printer.println()
   }
 }
 

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -206,13 +206,15 @@ extension JNISwift2JavaGenerator {
     printDeclDocumentation(&printer, decl)
     printer.printBraceBlock("public \(renderFunctionSignature(decl))") { printer in
       var arguments = translatedDecl.translatedFunctionSignature.parameters.map(\.name)
-      arguments.append("selfPointer")
+
+      let selfVarName = "self$"
+      arguments.append(selfVarName)
 
       let returnKeyword = translatedDecl.translatedFunctionSignature.resultType.isVoid ? "" : "return "
 
       printer.print(
         """
-        long selfPointer = this.pointer();
+        long \(selfVarName) = this.$memoryAddress();
         \(returnKeyword)\(translatedDecl.parentName).$\(translatedDecl.name)(\(arguments.joined(separator: ", ")));
         """
       )
@@ -235,8 +237,8 @@ extension JNISwift2JavaGenerator {
       let initArguments = translatedDecl.translatedFunctionSignature.parameters.map(\.name)
       printer.print(
         """
-        long selfPointer = \(type.qualifiedName).allocatingInit(\(initArguments.joined(separator: ", ")));
-        return new \(type.qualifiedName)(selfPointer, swiftArena$);
+        long self$ = \(type.qualifiedName).allocatingInit(\(initArguments.joined(separator: ", ")));
+        return new \(type.qualifiedName)(self$, swiftArena$);
         """
       )
     }
@@ -262,15 +264,24 @@ extension JNISwift2JavaGenerator {
   private func printDestroyFunction(_ printer: inout CodePrinter, _ type: ImportedNominalType) {
     printer.print("private static native void $destroy(long selfPointer);")
 
+    let funcName = "$createDestroyFunction"
     printer.print("@Override")
-    printer.printBraceBlock("protected Runnable $createDestroyFunction()") { printer in
+    printer.printBraceBlock("protected Runnable \(funcName)()") { printer in
       printer.print(
         """
-        long $selfPointer = this.pointer(); 
+        long self$ = this.$memoryAddress();
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall("\(type.swiftNominal.name).\(funcName)",
+              "this", this,
+              "self", self$);
+        }
         return new Runnable() {
           @Override
           public void run() {
-            \(type.swiftNominal.name).$destroy($selfPointer);
+            if (CallTraces.TRACE_DOWNCALLS) {
+              CallTraces.traceDowncall("\(type.swiftNominal.name).$destroy", "self", self$);
+            }
+            \(type.swiftNominal.name).$destroy(self$);
           }
         };
         """

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -138,9 +138,9 @@ extension JNISwift2JavaGenerator {
       // TODO: Throwing initializers
       printer.print(
         """
-        let selfPointer = UnsafeMutablePointer<\(typeName)>.allocate(capacity: 1)
-        selfPointer.initialize(to: \(typeName)(\(downcallArguments)))
-        return Int64(Int(bitPattern: selfPointer)).getJNIValue(in: environment)
+        let self$ = UnsafeMutablePointer<\(typeName)>.allocate(capacity: 1)
+        self$.initialize(to: \(typeName)(\(downcallArguments)))
+        return Int64(Int(bitPattern: self$)).getJNIValue(in: environment)
         """
       )
     }
@@ -184,22 +184,20 @@ extension JNISwift2JavaGenerator {
     let translatedDecl = self.translatedDecl(for: decl)! // We will only call this method if can translate the decl.
     let swiftParentName = decl.parentType!.asNominalTypeDeclaration!.qualifiedName
 
+    let selfPointerParam = JavaParameter(name: "selfPointer", type: .long)
     printCDecl(
       &printer,
       javaMethodName: "$\(translatedDecl.name)",
       parentName: translatedDecl.parentName,
       parameters: translatedDecl.translatedFunctionSignature.parameters + [
-        JavaParameter(name: "selfPointer", type: .long)
+        selfPointerParam
       ],
       isStatic: true,
       resultType: translatedDecl.translatedFunctionSignature.resultType
     ) { printer in
-      printer.print(
-        """
-        let self$ = UnsafeMutablePointer<\(swiftParentName)>(bitPattern: Int(Int64(fromJNI: selfPointer, in: environment!)))!
-        """
-      )
-      self.printFunctionDowncall(&printer, decl, calleeName: "self$.pointee")
+      let selfVar = self.printSelfJLongToUnsafeMutablePointer(&printer,
+          swiftParentName: swiftParentName, selfPointerParam)
+      self.printFunctionDowncall(&printer, decl, calleeName: "\(selfVar).pointee")
     }
   }
 
@@ -320,28 +318,53 @@ extension JNISwift2JavaGenerator {
 
   /// Prints the implementation of the destroy function.
   private func printDestroyFunctionThunk(_ printer: inout CodePrinter, _ type: ImportedNominalType) {
+    let selfPointerParam = JavaParameter(name: "selfPointer", type: .long)
     printCDecl(
       &printer,
       javaMethodName: "$destroy",
       parentName: type.swiftNominal.name,
       parameters: [
-        JavaParameter(name: "selfPointer", type: .long)
+        selfPointerParam
       ],
       isStatic: true,
       resultType: .void
     ) { printer in
+      let parentName = type.qualifiedName
+      let selfVar = self.printSelfJLongToUnsafeMutablePointer(&printer, swiftParentName: parentName, selfPointerParam)
       // Deinitialize the pointer allocated (which will call the VWT destroy method)
       // then deallocate the memory.
       printer.print(
         """
-        let pointer = UnsafeMutablePointer<\(type.qualifiedName)>(bitPattern: Int(Int64(fromJNI: selfPointer, in: environment!)))!
-        pointer.deinitialize(count: 1)
-        pointer.deallocate()
+        \(selfVar).deinitialize(count: 1)
+        \(selfVar).deallocate()
         """
       )
     }
   }
 
+  /// Print the necessary conversion logic to go from a `jlong` to a `UnsafeMutablePointer<Type>`
+  ///
+  /// - Returns: name of the created "self" variable
+  private func printSelfJLongToUnsafeMutablePointer(
+      _ printer: inout CodePrinter,
+      swiftParentName: String, _ selfPointerParam: JavaParameter) -> String {
+    let newSelfParamName = "self$"
+    printer.print(
+      """
+      guard let env$ = environment else {
+        fatalError("Missing JNIEnv in downcall to \\(#function)")
+      }
+      assert(\(selfPointerParam.name) != 0, "\(selfPointerParam.name) memory address was null")
+      let selfBits$ = Int(Int64(fromJNI: \(selfPointerParam.name), in: env$))
+      guard let \(newSelfParamName) = UnsafeMutablePointer<\(swiftParentName)>(bitPattern: selfBits$) else {
+        fatalError("self memory address was null in call to \\(#function)!")
+      }
+      """
+    )
+    return newSelfParamName
+  }
+
+
   /// Renders the arguments for making a downcall
   private func renderDowncallArguments(
     swiftFunctionSignature: SwiftFunctionSignature,

SwiftKitCore/src/main/java/org/swift/swiftkit/core/CallTraces.java

@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// 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.core;
+
+public class CallTraces {
+    public static final boolean TRACE_DOWNCALLS =
+        Boolean.getBoolean("jextract.trace.downcalls");
+
+    // Used to manually debug with complete backtraces on every traceDowncall
+    public static final boolean TRACE_DOWNCALLS_FULL = false;
+
+    public static void traceDowncall(Object... args) {
+        RuntimeException ex = new RuntimeException();
+
+        String traceArgs = joinArgs(args);
+        System.err.printf("[java][%s:%d] Downcall: %s.%s(%s)\n",
+                ex.getStackTrace()[1].getFileName(),
+                ex.getStackTrace()[1].getLineNumber(),
+                ex.getStackTrace()[1].getClassName(),
+                ex.getStackTrace()[1].getMethodName(),
+                traceArgs);
+        if (TRACE_DOWNCALLS_FULL) {
+            ex.printStackTrace();
+        }
+    }
+
+    public static void trace(Object... args) {
+        RuntimeException ex = new RuntimeException();
+
+        String traceArgs = joinArgs(args);
+        System.err.printf("[java][%s:%d] %s: %s\n",
+                ex.getStackTrace()[1].getFileName(),
+                ex.getStackTrace()[1].getLineNumber(),
+                ex.getStackTrace()[1].getMethodName(),
+                traceArgs);
+    }
+
+    private static String joinArgs(Object[] args) {
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < args.length; i++) {
+            if (i > 0) {
+                sb.append(", ");
+            }
+            sb.append(args[i].toString());
+        }
+        return sb.toString();
+    }
+
+}

SwiftKitCore/src/main/java/org/swift/swiftkit/core/ConfinedSwiftMemorySession.java

@@ -60,7 +60,7 @@ public void close() {
     public void register(SwiftInstance instance) {
         checkValid();
 
-        SwiftInstanceCleanup cleanup = instance.createCleanupAction();
+        SwiftInstanceCleanup cleanup = instance.$createCleanup();
         this.resources.add(cleanup);
     }
 

SwiftKitCore/src/main/java/org/swift/swiftkit/core/JNISwiftInstance.java

@@ -14,17 +14,30 @@
 
 package org.swift.swiftkit.core;
 
+import java.util.Objects;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 public abstract class JNISwiftInstance extends SwiftInstance {
+    // Pointer to the "self".
+    protected final long selfPointer;
+
     /**
      * The designated constructor of any imported Swift types.
      *
-     * @param pointer a pointer to the memory containing the value
+     * @param selfPointer a pointer to the memory containing the value
      * @param arena   the arena this object belongs to. When the arena goes out of scope, this value is destroyed.
      */
-    protected JNISwiftInstance(long pointer, SwiftArena arena) {
-        super(pointer, arena);
+    protected JNISwiftInstance(long selfPointer, SwiftArena arena) {
+        SwiftObjects.requireNonZero(selfPointer, "selfPointer");
+        this.selfPointer = selfPointer;
+
+        // Only register once we have fully initialized the object since this will need the object pointer.
+        arena.register(this);
+    }
+
+    @Override
+    public long $memoryAddress() {
+        return this.selfPointer;
     }
 
     /**
@@ -42,7 +55,7 @@ protected JNISwiftInstance(long pointer, SwiftArena arena) {
     protected abstract Runnable $createDestroyFunction();
 
     @Override
-    public SwiftInstanceCleanup createCleanupAction() {
+    public SwiftInstanceCleanup $createCleanup() {
         final AtomicBoolean statusDestroyedFlag = $statusDestroyedFlag();
         Runnable markAsDestroyed = new Runnable() {
             @Override