add FFM.Critical to annotate a function as critical (direct access to Java Heap)

Author: pquiring

src/javaforce/ffm/Critical.java

@@ -0,0 +1,19 @@
+package javaforce.ffm;
+
+/** JNI2FFM annotation.
+ *
+ * Indicates native function is critical.
+ *
+ * See Linker.Option.critical()
+ *
+ * @author pquiring
+ */
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.SOURCE)
+@Target(ElementType.METHOD)
+public @interface Critical {}

src/javaforce/ffm/FFM.java

@@ -190,6 +190,34 @@ public MethodHandle getFunctionPtr(String name, FunctionDescriptor fd) {
     }
   }
 
+  /** Get native MethodHandle for specified function name with FunctionDescriptor where the symbol is a function pointer. */
+  public MethodHandle getFunctionPtrCritical(String name, FunctionDescriptor fd) {
+    if (debug) JFLog.log("FFM:getFunctionPtr:" + name);
+    try {
+      MemorySegment addr = lookup.findOrThrow(name);
+      if (addr == null || addr.address() == 0) {
+        JFLog.log("FFM:FunctionPtr not found(1):" + name + "=" + addr);
+        return null;
+      }
+      //symbols have zero length, need to reinterpret as a pointer
+      addr = addr.reinterpret(ADDRESS_SIZE);
+      if (addr == null || addr.address() == 0) {
+        JFLog.log("FFM:FunctionPtr not found(2):" + name + "=" + addr);
+        return null;
+      }
+      //now get the contents of the pointer
+      addr = addr.get(ADDRESS, 0);
+      if (addr == null || addr.address() == 0) {
+        JFLog.log("FFM:FunctionPtr not found(3):" + name + "=" + addr);
+        return null;
+      }
+      return linker.downcallHandle(addr, fd, Linker.Option.critical(true));
+    } catch (Exception e) {
+      JFLog.logTrace("FFM:FunctionPtr not found(e):" + name);
+      return null;
+    }
+  }
+
   //upcall helpers
 
   private static ValueLayout classToValueLayout(Class<?> cls) {
@@ -333,6 +361,44 @@ public static MemorySegment toMemory(Arena arena, MemorySegment[] ptrs) {
     return array;
   }
 
+  //array helpers (critical)
+
+  /** Create native array from float[] */
+  public static MemorySegment toMemory(float[] m) {
+    if (m == null) return MemorySegment.NULL;
+    return MemorySegment.ofArray(m);
+  }
+
+  /** Create native array from double[] */
+  public static MemorySegment toMemory(double[] m) {
+    if (m == null) return MemorySegment.NULL;
+    return MemorySegment.ofArray(m);
+  }
+
+  /** Create native array from long[] */
+  public static MemorySegment toMemory(long[] m) {
+    if (m == null) return MemorySegment.NULL;
+    return MemorySegment.ofArray(m);
+  }
+
+  /** Create native array from int[] */
+  public static MemorySegment toMemory(int[] m) {
+    if (m == null) return MemorySegment.NULL;
+    return MemorySegment.ofArray(m);
+  }
+
+  /** Create native array from short[] */
+  public static MemorySegment toMemory(short[] m) {
+    if (m == null) return MemorySegment.NULL;
+    return MemorySegment.ofArray(m);
+  }
+
+  /** Create native array from byte[] */
+  public static MemorySegment toMemory(byte[] m) {
+    if (m == null) return MemorySegment.NULL;
+    return MemorySegment.ofArray(m);
+  }
+
   private static final long JAVA_LONG_SIZE = JAVA_LONG.byteSize();
   private static final long JAVA_INT_SIZE = JAVA_INT.byteSize();
   private static final long JAVA_SHORT_SIZE = JAVA_SHORT.byteSize();

src/javaforce/ffm/JNI2FFM.java

@@ -61,6 +61,7 @@ public static void main(String[] args) {
 
     boolean flag_nofreestring = false;
     boolean flag_nocopyback = false;
+    boolean flag_critical = false;
 
     try {
 
@@ -117,6 +118,10 @@ public static void main(String[] args) {
           flag_nocopyback = true;
           continue;
         }
+        if (ln.equals("@Critical")) {
+          flag_critical = true;
+          continue;
+        }
         if (!ln.startsWith("public native")) continue;
         //public native void glActiveTexture(int i1);
         ln = ln.substring(14, ln.length() - 1);
@@ -177,7 +182,7 @@ public static void main(String[] args) {
         method.append(func_name);
         method.append(".invokeExact(");
 
-        ctor2.append("    " + func_name + " = ffm.getFunctionPtr(\"_" + func_name + "\", ffm.getFunctionDesciptor");
+        ctor2.append("    " + func_name + " = ffm.getFunctionPtr" + (flag_critical ? "Critical": "") + "(\"_" + func_name + "\", ffm.getFunctionDesciptor");
         boolean first = true;
         boolean first_ctor = true;
         if (isRetVoid) {
@@ -228,7 +233,7 @@ public static void main(String[] args) {
           if (isArray) {
             array_names.add(arg_name);
             String segment_name = "_array_" + arg_name;
-            arrays.append("MemorySegment " + segment_name + " = FFM.toMemory(arena, " + arg_name + ");");
+            arrays.append("MemorySegment " + segment_name + " = FFM.toMemory(" + (flag_critical ? "" : "arena, ") + arg_name + ");");
             method.append(segment_name);
             arena_needed = true;
           } else {
@@ -306,6 +311,7 @@ public static void main(String[] args) {
         }
         flag_nofreestring = false;
         flag_nocopyback = false;
+        flag_critical = false;
       }
       ctor.append("    return true;\n");
       ctor.append("  }\n");

src/javaforce/jni/MediaJNI.java

@@ -6,6 +6,7 @@
  */
 
 import javaforce.api.*;
+import javaforce.ffm.*;
 import javaforce.media.*;
 
 public class MediaJNI implements MediaAPI {