Utils: UninitializedByteBuffer

dhfs-parent/dhfs-app/src/test/java/com/usatiuk/dhfsapp/integration/DhfsImage.java

@@ -70,6 +70,7 @@ public class DhfsImage implements Future<String> {
                                         "--add-exports", "java.base/sun.nio.ch=ALL-UNNAMED",
                                         "--add-exports", "java.base/jdk.internal.access=ALL-UNNAMED",
                                         "--add-opens=java.base/java.nio=ALL-UNNAMED",
+                                        "--enable-preview",
                                         "-Ddhfs.objects.peerdiscovery.interval=1s",
                                         "-Ddhfs.objects.invalidation.delay=100",
                                         "-Ddhfs.objects.deletion.delay=0",

dhfs-parent/objects/src/main/java/com/usatiuk/objects/JObjectKeyImpl.java

@@ -46,7 +46,7 @@ public final class JObjectKeyImpl implements JObjectKey {
         synchronized (this) {
             if (_bb != null) return _bb;
             var bytes = value.getBytes(StandardCharsets.ISO_8859_1);
-            var directBb = ByteBuffer.allocateDirect(bytes.length);
+            var directBb = UninitializedByteBuffer.allocate(bytes.length);
             directBb.put(bytes);
             directBb.flip();
             _bb = directBb;

dhfs-parent/pom.xml

@@ -102,6 +102,7 @@
                         <arg>-parameters</arg>
                         <arg>--add-exports</arg>
                         <arg>java.base/jdk.internal.access=ALL-UNNAMED</arg>
+                        <arg>--enable-preview</arg>
                     </compilerArgs>
                 </configuration>
             </plugin>
@@ -119,6 +120,7 @@
                         --add-exports java.base/sun.nio.ch=ALL-UNNAMED
                         --add-exports java.base/jdk.internal.access=ALL-UNNAMED
                         --add-opens=java.base/java.nio=ALL-UNNAMED
+                        --enable-preview
                     </argLine>
                     <skipTests>${skip.unit}</skipTests>
                     <redirectTestOutputToFile>true</redirectTestOutputToFile>

dhfs-parent/utils/src/main/java/com/usatiuk/utils/UninitializedByteBuffer.java

@@ -0,0 +1,44 @@
+package com.usatiuk.utils;
+
+import java.lang.foreign.*;
+import java.lang.invoke.MethodHandle;
+import java.nio.ByteBuffer;
+import java.util.function.Consumer;
+
+public class UninitializedByteBuffer {
+    private static final Linker LINKER = Linker.nativeLinker();
+    private static final MethodHandle malloc = LINKER.downcallHandle(
+            LINKER.defaultLookup().find("malloc").orElseThrow(),
+            FunctionDescriptor.of(ValueLayout.ADDRESS, ValueLayout.JAVA_LONG)
+    );
+    private static final MethodHandle free = LINKER.downcallHandle(
+            LINKER.defaultLookup().find("free").orElseThrow(),
+            FunctionDescriptor.ofVoid(ValueLayout.ADDRESS)
+    );
+
+    public static ByteBuffer allocate(int capacity) {
+        UnsafeAccessor.get().getNioAccess().reserveMemory(capacity, capacity);
+
+        MemorySegment segment = null;
+        try {
+            segment = (MemorySegment) malloc.invokeExact((long) capacity);
+        } catch (Throwable e) {
+            throw new RuntimeException(e);
+        }
+
+        Consumer<MemorySegment> cleanup = s -> {
+            try {
+                free.invokeExact(s);
+                UnsafeAccessor.get().getNioAccess().unreserveMemory(capacity, capacity);
+            } catch (Throwable e) {
+                throw new RuntimeException(e);
+            }
+        };
+        var reint = segment.reinterpret(capacity, Arena.ofAuto(), cleanup);
+        return reint.asByteBuffer();
+    }
+
+    public static long getAddress(ByteBuffer buffer) {
+        return UnsafeAccessor.get().getNioAccess().getBufferAddress(buffer);
+    }
+}