generate code for memory management with SwiftKitCore

Author: madsodgaard

Samples/JExtractJNISampleApp/src/main/java/com/example/swift/HelloJava2SwiftJNI.java

@@ -19,6 +19,7 @@
 // Import javakit/swiftkit support libraries
 
 import org.swift.swiftkit.core.SwiftLibraries;
+import org.swift.swiftkit.core.ConfinedSwiftMemorySession;
 
 public class HelloJava2SwiftJNI {
 
@@ -40,8 +41,10 @@ static void examples() {
 
         MySwiftClass.method();
 
-        MySwiftClass myClass = MySwiftClass.init(10, 5);
-        MySwiftClass myClass2 = MySwiftClass.init();
+        try (var arena = new ConfinedSwiftMemorySession(Thread.currentThread())) {
+            MySwiftClass myClass = MySwiftClass.init(10, 5, arena);
+            MySwiftClass myClass2 = MySwiftClass.init(arena);
+        }
 
         System.out.println("DONE.");
     }

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -12,6 +12,19 @@
 //
 //===----------------------------------------------------------------------===//
 
+
+// MARK: Defaults
+
+extension JNISwift2JavaGenerator {
+  /// Default set Java imports for every generated file
+  static let defaultJavaImports: Array<String> = [
+    "org.swift.swiftkit.core.*",
+    "org.swift.swiftkit.core.util.*",
+  ]
+}
+
+// MARK: Printing
+
 extension JNISwift2JavaGenerator {
   func writeExportedJavaSources() throws {
     var printer = CodePrinter()
@@ -72,6 +85,7 @@ extension JNISwift2JavaGenerator {
   private func printImportedNominal(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
     printHeader(&printer)
     printPackage(&printer)
+    printImports(&printer)
 
     printNominal(&printer, decl) { printer in
       printer.print(
@@ -87,14 +101,10 @@ extension JNISwift2JavaGenerator {
         """
       )
 
-      printer.println()
-
       printer.print(
         """
-        private long selfPointer;
-        
-        private \(decl.swiftNominal.name)(long selfPointer) {
-          this.selfPointer = selfPointer;
+        public \(decl.swiftNominal.name)(long selfPointer, SwiftArena swiftArena) {
+          super(selfPointer, swiftArena);
         }
         """
       )
@@ -108,6 +118,8 @@ extension JNISwift2JavaGenerator {
       for method in decl.methods {
         printFunctionBinding(&printer, method)
       }
+
+      printDestroyFunction(&printer, decl)
     }
   }
 
@@ -130,10 +142,17 @@ extension JNISwift2JavaGenerator {
     )
   }
 
+  private func printImports(_ printer: inout CodePrinter) {
+    for i in JNISwift2JavaGenerator.defaultJavaImports {
+      printer.print("import \(i);")
+    }
+    printer.print("")
+  }
+
   private func printNominal(
     _ printer: inout CodePrinter, _ decl: ImportedNominalType, body: (inout CodePrinter) -> Void
   ) {
-    printer.printBraceBlock("public final class \(decl.swiftNominal.name)") { printer in
+    printer.printBraceBlock("public final class \(decl.swiftNominal.name) extends JNISwiftInstance") { printer in
       body(&printer)
     }
   }
@@ -160,7 +179,7 @@ extension JNISwift2JavaGenerator {
       printer.print(
         """
         long selfPointer = \(type.qualifiedName).allocatingInit(\(initArguments.joined(separator: ", ")));
-        return new \(type.qualifiedName)(selfPointer);
+        return new \(type.qualifiedName)(selfPointer, swiftArena$);
         """
       )
     }
@@ -182,14 +201,39 @@ extension JNISwift2JavaGenerator {
     )
   }
 
+  /// Prints the destroy function for a `JNISwiftInstance`
+  private func printDestroyFunction(_ printer: inout CodePrinter, _ type: ImportedNominalType) {
+    printer.print("private static native void $destroy(long selfPointer);")
+
+    printer.print("@Override")
+    printer.printBraceBlock("protected Runnable $createDestroyFunction()") { printer in
+      printer.print(
+        """
+        long $selfPointer = this.pointer(); 
+        return new Runnable() {
+          @Override
+          public void run() {
+            \(type.swiftNominal.name).$destroy($selfPointer);
+          }
+        };
+        """
+      )
+    }
+  }
+
   /// Renders a Java function signature
   ///
   /// `func method(x: Int, y: Int) -> Int` becomes
   /// `long method(long x, long y)`
   private func renderFunctionSignature(_ decl: ImportedFunc) -> String {
     let translatedDecl = translatedDecl(for: decl)
     let resultType = translatedDecl.translatedFunctionSignature.resultType
-    let parameters = translatedDecl.translatedFunctionSignature.parameters.map(\.asParameter)
+    var parameters = translatedDecl.translatedFunctionSignature.parameters.map(\.asParameter)
+
+    if decl.isInitializer {
+      parameters.append("SwiftArena swiftArena$")
+    }
+
     let throwsClause = decl.isThrowing ? " throws Exception" : ""
 
     return "\(resultType) \(translatedDecl.name)(\(parameters.joined(separator: ", ")))\(throwsClause)"

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -13,6 +13,11 @@
 //===----------------------------------------------------------------------===//
 
 import JavaTypes
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
 
 extension JNISwift2JavaGenerator {
   func writeSwiftThunkSources() throws {
@@ -96,6 +101,8 @@ extension JNISwift2JavaGenerator {
       printSwiftFunctionThunk(&printer, method)
       printer.println()
     }
+
+    printDestroyFunctionThunk(&printer, type)
   }
 
   private func printInitializerThunk(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
@@ -199,24 +206,18 @@ extension JNISwift2JavaGenerator {
     resultType: JavaType,
     _ body: (inout CodePrinter) -> Void
   ) {
-    var jniSignature = parameters.reduce(into: "") { signature, parameter in
+    let jniSignature = parameters.reduce(into: "") { signature, parameter in
       signature += parameter.type.jniTypeSignature
     }
 
-    // Escape signature characters
-    jniSignature = jniSignature
-      .replacingOccurrences(of: "_", with: "_1")
-      .replacingOccurrences(of: "/", with: "_")
-      .replacingOccurrences(of: ";", with: "_2")
-      .replacingOccurrences(of: "[", with: "_3")
-
     let cName =
       "Java_"
       + self.javaPackage.replacingOccurrences(of: ".", with: "_")
-      + "_\(parentName)_"
-      + javaMethodName
+      + "_\(parentName.nativeJNIEscaped)_"
+      + javaMethodName.nativeJNIEscaped
       + "__"
-      + jniSignature
+      + jniSignature.nativeJNIEscaped
+
     let translatedParameters = parameters.map {
       "\($0.name): \($0.type.jniTypeName)"
     }
@@ -251,6 +252,30 @@ extension JNISwift2JavaGenerator {
     )
   }
 
+  /// Prints the implementation of the destroy function.
+  private func printDestroyFunctionThunk(_ printer: inout CodePrinter, _ type: ImportedNominalType) {
+    printCDecl(
+      &printer,
+      javaMethodName: "$destroy",
+      parentName: type.swiftNominal.name,
+      parameters: [
+        JavaParameter(name: "selfPointer", type: .long)
+      ],
+      isStatic: true,
+      resultType: .void
+    ) { printer in
+      // 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()
+        """
+      )
+    }
+  }
+
   /// Renders the arguments for making a downcall
   private func renderDowncallArguments(
     swiftFunctionSignature: SwiftFunctionSignature,
@@ -266,3 +291,29 @@ extension JNISwift2JavaGenerator {
     .joined(separator: ", ")
   }
 }
+
+extension String {
+  /// Returns a version of the string correctly escaped for a JNI
+  var nativeJNIEscaped: String {
+    self.map {
+      if $0 == "_" {
+        return "_1"
+      } else if $0 == "/" {
+        return "_"
+      } else if $0 == ";" {
+        return "_2"
+      } else if $0 == "[" {
+        return "_3"
+      } else if $0.isASCII && ($0.isLetter || $0.isNumber)  {
+        return String($0)
+      } else if let utf16 = $0.utf16.first {
+        // Escape any non-alphanumeric to their UTF16 hex encoding
+        let utf16Hex = String(format: "%04x", utf16)
+        return "_0\(utf16Hex)"
+      } else {
+        fatalError("Invalid JNI character: \($0)")
+      }
+    }
+    .joined()
+  }
+}

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

@@ -39,7 +39,7 @@ protected JNISwiftInstance(long pointer, SwiftArena arena) {
      *
      * @return a function that is called when the value should be destroyed.
      */
-    abstract Runnable $createDestroyFunction();
+    protected abstract Runnable $createDestroyFunction();
 
     @Override
     public SwiftInstanceCleanup createCleanupAction() {